Automated Loading and Unloading System for

Getinge Corporation, USA

Final ReportMay 14, 2004Thanasis Gkourlias

Derek ArnoldLawrence Derdzinski

Amber MescherChris Sangster

Timothy Gallman

Executive Summary

This final report defines the design of the Automated Loading and Unloading

System for Getinge Corporation. The Automated Loading and Unloading System will be

a self-guided, reprogrammable, automated guided vehicle (AGV) type product that is

capable of loading and unloading medical carts of various sizes into Getinge's washing

machines. This system, Getinge Model 2040, is offered as an option to the Getinge

Model 7800 Floor Loading Cart Washer. The robotic device will transport the carts to a

washing machine, mainly used in hospitals.

The goal of this project is to design, fabricate, debug, and test this automated

system (robot) to prove its ability to load and unload medical carts.

The Automated Loading and Unloading Team designed all aspects of the robotic

solution. This includes the robot frame (housing), wiring, controls, integration and

operator interface, drive system, docking and latching, navigation, and charging system.

The product will safely operate within a hospital central supply environment.

The existing automated systems, with which this system will compete, require

invasive construction in the floor to install big components that lead the carts into the

washing machine. In opposition to the existing systems, the new Automated Loading and

Unloading System is going to be compact, flexible, safe, easy to move, and

reprogrammable. The team implemented the Engineering Design Planner methodology

to design the robot. There are five design stages of the process. The first stage of the

report, recognizing and quantifying the need, discusses the goals, motivation, and

background of the project. The second stage presents an overview of four concepts the

2

team has developed. The next stage presents the feasibility assessment the team

conducted for each of the four concepts. The fourth stage presents a detailed description

of the goals of the project as well as specifications of the design. The fifth stage,

describes the analysis that has been done to design the automated system. Finally, the

description of the experiments that were performed and a plan for finishing the project on

schedule and within budget are presented. Technical data along with the summary of the

current status of the project are included.

The robot design continued to be refined while multiple activities occurred. As

brainstorming, customer requirements, feasibility studies, and technology searches

continued to be refined, the design solidified. The initial design did not turn out to be the

final design.

The final design of the robot is shown with the drawings included in the technical

data package. The package has both assembly and part drawings.

3

Table of Contents Executive Summary...........................................................................................................2

1.0 Recognize and Quantify the Need........................................................................71.1 Project Mission Statement.........................................................................................71.2 Product Description..................................................................................................71.3 Scope Limitations....................................................................................................101.4 Stake Holders...........................................................................................................111.5 Key Business Goals.................................................................................................111.6 Top Level Critical Financial Parameters................................................................111.7 Financial Analysis...................................................................................................121.8 Primary Market.......................................................................................................121.9 Secondary Market....................................................................................................131.10 Order Qualifiers....................................................................................................131.11 Order Winners.......................................................................................................131.12 Innovation Opportunities.......................................................................................141.13 Background Research............................................................................................14

2.0 Concept Development................................................................................................172.1 Building vs. Buying..................................................................................................172.2 Cart Towing Concept...............................................................................................182.3 Power System Concept............................................................................................192.4 Control System Concept..........................................................................................192.5 Drive System Concept..............................................................................................192.6 Navigation System Concept.....................................................................................202.7 Communication System Concept.............................................................................202.8 Cart Detection System Concept...............................................................................212.9 Retro Fit Concept....................................................................................................212.10 Concept Development Conclusion.........................................................................22

3.0 Feasibility Assessment...............................................................................................233.1 Building vs. Buying..................................................................................................233.2 Cart Towing Feasibility...........................................................................................243.3 Power System Feasibility.........................................................................................253.4 Control System Feasibility.......................................................................................253.5 Drive System Feasibility..........................................................................................253.6 Navigation System Feasibility.................................................................................263.7 Communication System Feasibility.........................................................................263.8 Cart Detection System Feasibility...........................................................................273.9 Retro Fit Feasibility.................................................................................................273.10 Feasibility Conclusion...........................................................................................28

4.0 Performance Objectives and Specifications............................................................294.1 Design Objective......................................................................................................294.2 Performance Specifications.....................................................................................304.3 Design Practices Used by the Team........................................................................334.4 Safety Issues.............................................................................................................34

4

5.0 Analysis of Problem and Synthesis of Design..........................................................365.1 Housing Design.......................................................................................................365.2 Control System.........................................................................................................375.3 Pin Mechanism Design............................................................................................385.4 Drive System............................................................................................................395.5 Navigation System...................................................................................................415.6 Mounting Design.....................................................................................................425.7 Retro Fit Kit.............................................................................................................445.8 Power Supply Selection...........................................................................................455.9 The Charging System...............................................................................................465.10 Cart Towing...........................................................................................................475.11 Cart Recognition....................................................................................................475.12 Overall design/Analysis Conclusion......................................................................485.13 Software Specifications..........................................................................................49

6.0 Test Protocols.............................................................................................................55

7.0 Budget.........................................................................................................................56

8.0 Future Plans...............................................................................................................57

References:.......................................................................................................................59

List of Appendices............................................................................................................61Appendix F: Test Protocols...........................................................................................61Appendix G: Test Protocol............................................Error! Bookmark not defined.

5

List of Illustrations

Figure 1.1: Belimed Automated Loading and Unloading System ..............................14

Figure 1.2: Tug in Action.............................................................................................15

Figure 2.1: Two-pin Robot Design..............................................................................18

Figure 5.1: Robot Frame .............................................................................................36

Figure 5.2: Housing Top Cover .................................................................................37

Figure 5.3: Cam...........................................................................................................38

Figure 5.4: Pin Mechanism..........................................................................................39

Figure 5.5: Drive System in Mounting Bracket...........................................................39

Figure 5.6: Calculation of Drive Motor Torque and Power.........................................41

Figure 5.7: Motor Bracket............................................................................................42

Figure 5.8: Rear Bracket for IR Sensor Array and Camera.........................................43

Figure 5.9: Front Bracket for IR Sensor Array and Camera........................................44

Figure 5.10: Retro Fit Kit.............................................................................................44

Figure 5.11: Wire Frame Kit........................................................................................45

Figure 5.12: Charging Stations....................................................................................46

Figure 5.13: Overall Design of Robot..........................................................................48

Table 1: Motor Control Commands.............................................................................53

Table 2: Pin H-Bridge Conditions...............................................................................54

6

1.0 Recognize and Quantify the Need

1.1 Project Mission Statement

The Automated Loading and Unloading System Senior Design Team is to design

and fabricate a working prototype in conjunction with Getinge USA. This prototype will

be used to help hospitals manage their personnel. This will allow the hospital washing

area to be more efficient, leaving extra personnel for other needs. A secondary goal of

the project is to release the system in conjunction with the new Getinge 7800 series

washer, which will be released in October 2004.

1.2 Product Description

One of the most significant problems in designing a competitive Automated

Loading and Unloading System for hospital medical cart washers is their bulk. This bulk

takes up valuable room in a hospital cleaning area. Based on customer feedback, Getinge

USA needed an Automated Loading and Unloading System that would be a self-guided,

fully automated, non-invasive, robot type product that is small in size. The system

should be capable of loading and unloading large floor loading washing machines with

medical carts of various sizes and weights. There must be two robots: one for loading the

medical carts on the soiled side of the washer and another for unloading the medical carts

on the clean side of the washer. This is required because the robot cannot go between the

two areas without causing contamination.

The advantage of a robot-type loading and unloading system is that it occupies

much less of the valuable hospital floor space than the other systems available today. It

7

relieves hospital’s staff members from the loading and unloading task. This staff member

can then do tasks of more value for the hospital.

The Senior Design team used this idea to design a mobile robot. This design

includes concepts of the robot frame and covering, wiring, controls, drive system,

docking and latching systems, tracking system, safety system, charging system, and the

necessary integration. The robot was designed to be small enough to fit underneath the

medical carts. The smallest medical cart has five and a half inches of clearance between

the bottom of the medical cart and the ground. The docking and latching system includes

a retrofit kit designed to allow the robot to latch to medical carts of different ground

clearances.

The product specifications that Getinge provided state that the robot needs to

produce about fifty pounds of linear force, besides the force needed to pull its own

weight. In order to be strong enough to move and fit under the medical cart, the robot’s

components, including batteries, motors, and the pin used to connect to the medical cart

needed to be very powerful and still less than four inches in height. This was the biggest

challenge of the project.

Since this is a mobile robot, the only power source available is battery power.

The batteries will not last long enough to be disposable, so recharging is necessary. Each

system will include a charging station where the robot can short-cycle charge during the

wash cycle.

There is more than one type of medical car used in the hospital. The robot needed

to differentiate between these carts. A recognition system, which consists of a colored

block, will be placed inside one of the cart doors such that when the door opens it is

8

centered at the end of the cart. The robot will read the color code with the camera and

use this information to select the preferred type of cart. The type of cart loaded into the

washer determines the washing cycle. The robot can communicate the type of cart

loaded and therefore the proper washing cycle through the charging station.

RF communications cannot be used in hospitals. Due to this constraint, an

infrared communication system will be used to communicate wirelessly between the

robot and the charging station. The charging station will then convey pertinent

information to the washer by a hard-wired connection.

A control system is needed to ensure the system could travel from its home

location to the defined cart pick-up area and then to the washer. An array of IR sensors

will be used on the bottom of the robot to track and follow lines on the floor. This will

allow the robot to move from the charger to the cart pick-up area. It will also allow the

robot to travel to the washer and load the cart properly. During this travel time, the robot

will continuously be sensing for obstacles through an array of long-range infrared sensors

on both the front and back of the robot. These sensors will allow for safe operation in a

busy area.

The microcontroller will be the brain of the operation. It will contain enough

input and output ports to address each device in the robot. The microcontroller needs to

be fast enough to process all information coming from all different components while

making decisions at the same time. Another microcontroller is placed at the charging

area to establish the communication between the two parts.

9

1.3 Scope Limitations

The prototyped Automated Loading and Unloading System shall be fully

designed by the end of RIT’s Fall Quarter, and assembled by the end of RIT’s Spring

Quarter.

At the end of the Fall Quarter, the senior design team held a Preliminary Design

Review. At this review the team was responsible for:

Complete design of the system

Drawing Package

Software flow charts

Bill of Materials

Quotes for Vendors

Budget

The senior design team will present the debugged and tested prototype. At this

presentation they will be responsible for:

Prototype

Final Report / Binder

Initial testing done using a medical cart

The senior design team will not be responsible for the following:

Washer Design

Washer Integration

Microcontroller Design

PLC Integration

Hospital Installation

10

1.4 Stake Holders

The main stakeholders in this project are the students working on the design and

the Getinge Corporation, USA. Other stakeholders are the hospitals and staff in which

these system will be integrated, and the future of Automated Loading and Unloading

Systems.

1.5 Key Business Goals

The team will be successful when they have designed a working Automated

Loading and Unloading System that requires very little human interaction. If this has

been done:

The students on the team have learned how to work on a multidisciplinary

team.

A proof of concept has been completed and can be requested for future

prototypes.

Getinge will now have an advantage on the other medical cart washer

production companies, and could profit immensely.

1.6 Top Level Critical Financial Parameters

Given the decision to have the robot travel under the medical carts, there was a

need for smaller components, which came at higher prices. The components that caused

the most concern were the H-Bridges, motors, track sensors, and pin mechanism for

hitching to the carts.

11

The scope of the project will require the robot to be very robust, which can be

costly. The robot needs to have reliable parts and certain aspects to withstand the

environment of the hospital, which may not have been considered in other environments.

1.7 Financial Analysis

A $10,000 budget has been appropriated for the cost of producing one robot. This

budget shall include:

Motors, Gearboxes, and Encoders

Microcontrollers, Motor controllers, Voltage regulators

Wheels

Attachment System including the pin system and the retrofit kit

Batteries and Battery Charger

Sensors

Chassis, and Body

Wires, Bolts, and Hardware

Extra Parts for Test

1.8 Primary Market

The primary market of the Automated Loading and Unloading System is hospitals

with Getinge 7800 Floor Loading Washing Machines.

12

1.9 Secondary Market

The Automated Loading and Unloading System could very easily be adapted to

other cart washing machines or other environments where a cart needs to be moved.

1.10 Order Qualifiers

The Automated Loading and Unloading Team shall fabricate, assemble, and

program a prototype that will load a medical cart into the Getinge 7800 Series Washer.

The team will also test qualify the robot in order to verify its power and efficiency.

1.11 Order Winners

The goals of the project conclude to the following statements:

Be small enough to fit underneath the smallest of the medical carts.

Be sufficiently powerful to pull the heaviest medical cart that is specified.

Be sufficiently reliable as defined in the specifications.

Meet safety requirements as defined in the specifications.

Have the need for very little human interaction.

Be able to sense the location and type of medical cart.

Verify that Engineering Design Models agree with prototype.

13

1.12 Innovation Opportunities

Potentially, the Automated Loading and Unloading System could be used with a

new Getinge 7800 Series Washer. Eventually, the Automated Loading and Unloading

System will be integrated into any hospital that uses a Getinge washing machine.

1.13 Background Research

The research completed by the Automated Loading and Unloading team consisted

of exploring systems in existence, robots on the market, and components.

Figure 1.1 - Belimed Automated System

Belimed makes a system where there is a track in front of the washer that pulls the

medical cart into and out of the washer. Steris also makes a system similar to this. The

problem with both of these systems is that they take up too much room in a hospital.

They also require a large amount of construction on the floor to install the system and

still require an operator. Getinge desired a solution that would not require a fulltime

operator or invasive floor construction.

14

There is also an automated robot available in production today, Tug by Aethon,

which pulls carts from one end of the hospital to the other using a built in map and by

tracing the walls. A disadvantage of Tug is that the carts have only two wheels, which

make them mobile only when Tug is attached. For the Automated Loading and

Unloading System desired by Getinge, the robot has to adapt to the medical carts, instead

of the carts adapting to the robot. Also, Tug costs about $35,000 to buy, which is out of

the range of the $10,000 budget provided by Getinge. Below is a picture of Tug in

action.

Figure 1.2 – Tug in Action

ActivMedia creates some other robots that are available and on the market today.

They have three robots that were considered for use by the team as base robots. These

robots would already work, but still need some modifications to achieve the application at

hand. One of their robots, called the PowerBot, can carry up to 220 pounds, map a room,

follow a path autonomously, maneuver in tight areas, and avoid obstacles. It has a lot of

things that we are looking for except for the fact that it is too big to fit under our medical

carts and would still need modification to work in the hospital environment. This robot

also cost roughly $20,000, which is way out of our cost range considering we would still

have to modify it. Another robot made by ActivMedia was the Pioneer 3-AT. It can only

15

carry a payload of 30 kg, and is also too tall to fit under a medical cart. It carries a base

price $5995, which is not totally out of our price range, but it would still require a lot of

modifications. The third robot that was considered from ActivMedia was the Pioneer 3-

DX. It’s not as powerful as the P3-AT, as it can only have a payload of 23 kg. This

carries a base price of $3695, and would also require a lot of modifications.

Angelus Research Corporations makes a robot called Whiskers the Intelligent

robot. It only costs $895, and is small enough to fit under a medical cart, but not strong

enough to pull it. It would also require a lot of major modifications to be able to meet the

required specifications.

Finally we found two robots made by Applied AI Systems, INC. called the

LABO-2, and the LABO-4. The LABO-4 costs $19,200 and has a payload of 90 kg. The

LABO-2 costs $20,400 and has a payload of about 135 kg. Both of these robots have the

type of power that we are looking for, but both don’t fit in the size constraints that we are

required to meet.

16

2.0 Concept Development

The Automated Loading and Unloading System team developed a large list of

possible ways of loading and unloading a medical cart into and out of the washer. This

list can be seen in the concept development part of the Engineering Design Planner

binder. The list of ideas originally contained 30 items. These ideas were discussed and

voted on to create a base of four ideas. The four most favorable ideas were: to design a

robot with arms that would surround the medical cart, to design a robot with a hook

which would pull the medical cart, to design a robot which would accept the pins from

the medical cart, and to design a robot which would lift the medical cart while accepting

a pin. Group drawings were formed and the ideas started the development stage.

2.1 Building vs. Buying

Getinge and the Model 2040 design team discussed various options on how to

complete this project in the twenty-week time frame allowed. The options included

building the system from components, buying a robot base and adding components, or

buying an existent robot. The project budget was $10,000, which devalued buying a

complete robot. Current robotic systems ranged in price from $35,000 to just under

$1000. Some systems did meet the capability requirements, but were out of our budget

range. Systems within the budget range did not meet the all constraints of the project.

Simply adding components to these systems would have not created sufficient

performance or would have been too costly. The final decision was to build the Model

2040 system from components.

17

2.2 Cart Towing Concept

A major aspect of the design was determining how to move the medical cart. The

first concept involved having the robot attach to two pins dropping down from the

medical cart. As this idea grew, so did the size of the robot (Fig. 2.1). The use of many

components caused the robot to no longer fit entirely under the cart, but rather partially

under and partially out from under the cart. This idea was developed and presented to the

customer.

Figure 2.1 - Two-pin Robot Design

For various reasons, the customer suggested a different design. This design was

for a robot that would fit under the medical cart entirely. A pin mechanism would rise

from the robot and mate with a hole in a mounting bracket attached to the medical cart.

The pin would slightly lift the one end of the cart off of its wheels causing enough

traction to pull the cart.

18

2.3 Power System Concept

One of the constraints of the project was that it be a mobile system able to move

freely about a defined area. This requirement led to a system with rechargeable batteries

and a charging / docking station. The system would require multiple batteries to provide

the power sufficient to drive motors, run sensors continuously, and keep a

microcontroller operating.

The charging station would have to be wall mounted to avoid being an obstruction

or safety hazard. Charging would occur during wash cycles, as needed.

2.4 Control System Concept

The initial plan for the control system was to modify and use an existing system.

The Whisker board from Angelus Research was chosen for the task. This board was to

be used as the base controller, while another board would be used in conjunction to

provide ample inputs and outputs. The microcontroller needed to handle the inputs and

outputs of all control sensors, as well as the encoders that would be used on the drive

motors.

Progress made using this concept was limited, due to a lack of reliability during

experimentation. Further research showed the manufacturer also lacked reliability. The

control design was then changed to one microcontroller with ample inputs and outputs.

2.5 Drive System Concept

The system’s requirement to be mobile led to the need for a drive system. Many

configurations were considered including four drive wheels, two drive wheels with two

19

casters, two drive wheels with two stationary wheels, and two drive wheels with one

caster.

The team decided upon a system that used two drive wheels with one caster due

mainly to space considerations. The drive wheels would use separate motors, allowing

the robot to be steered using different motor speeds for each wheel. This system mimics

the steering control of a track vehicle, such as a tank.

2.6 Navigation System Concept

A control system was needed to ensure the system could travel from its home

location to the defined cart pick-up area and then to the washer.

An array of IR track sensors was used on the bottom of the robot to track and

follow lines on the floor. This would allow the robot to follow a line from the charger to

the cart pick-up area and into the washer.

Another array of IR range sensors was used in the front and rear of the robot for

obstacle avoidance as it moves around the hospital floor.

2.7 Communication System Concept

One constraint imposed by hospital regulations was that no RF communication be

used. The use of RF is strictly regulated so that interference between different pieces of

vital equipment is not an issue.

The team decided to utilize IR communications in conjunction with a wired

connection to meet this constraint. IR signals were used to communicate between the

robot and the charging station. Through this transmission, the robot can convey when

20

and what type of cart has been loaded to the charging station. The charging station was

wired directly to the washer PLC, which allowed it to interpret the commands given from

the robot.

The charging station also has the ability to communicate with the robot. It

informs the robot when there is a certain amount of time left in the washing cycle. From

this communication, the robot knows when to get a cart and start loading it into the

washing machine.

2.8 Cart Detection System Concept

The medical cart detection process is completed in two stages. The first stage

involves using a camera to detect a certain color on the carts. The next stage involves

using IR track sensors to align and stop the robot at the hitch point in the retro fit kit.

The camera is capable of differentiating between various colors, so each type of

cart can use a colored block as an identifier. The color denotes the type of cart and

therefore the proper wash cycle.

2.9 Retro Fit Concept

An expansion of this project was that it eventually should be possible to use this

system on all existing medical carts, including those from other cart manufacturers. The

concept developed into a plate that fits across the bottom of the carts, between the two

front wheels. The plate has a hole in it designed to accept the pin mechanism from the

robot.

21

The module includes a system of encoded black and white blocks for IR

identification to align the robot’s pin mechanism with the hole in the retro fit kit.

2.10 Concept Development Conclusion

The preliminary design concept presents a robot that would travel under the

medical cart, raise a pin into the medical cart and pull the medical cart into the washer.

The robot is to be powered by batteries and built from the components stated previously.

The drive system consisted of two motors, with encoders, to drive each wheel separately

in a skid/steer design. There was one microcontroller to control the robot. This

microcontroller handled both the input and the output of the sensors and motor encoders.

The navigation system of the robot consisted of a camera and infrared sensors for

distance measurement and obstacle avoidance. Communication was provided to and

from the robot by infrared transceivers and between the charging station and the washing

machine by a hardwire connection. Another microcontroller is used in the charging area

to implement the messages from the robot. The robot is to detect types of medical carts

by means of color recognition through a camera. Each medical cart shall have a harness

to which the robot will mount. This makes for a complete system.

22

3.0 Feasibility Assessment

Feasibility was assessed using two methods. One method was Pugh’s method,

where four designs are compared against a base design. This method produces results

that are not always accurate because no aspect of the design is weighted more than the

others. The second method used for feasibility assessment was a weighted method. This

method proved to be much more accurate as it weighted the most important factors more

than the less important factors.

3.1 Building vs. Buying

The way the robot was to be produced was a great factor in the design of the

robot. The three choices that were considered were building the robot from scratch,

buying a base robot and adding components, or buying an existing robot. The first case

considered was buying an existing robot. While this was by far the quickest solution to

the company’s desires, it did not meet the cost constraints. The lowest priced robot was

found to be $35,000, while the project budget was $10,000. It also did not leave any

room for adaptations, which would be required for this specific project.

The second idea considered was buying a base robot and adding components to it.

This idea was entertained for a bit, as it would make programming and testing much

easier by guaranteeing that the robot base would work. This idea however, began to lose

favor when no base robots were found to be suitable for the application. The price was

also a factor as the base robots that were found were around $10,000, which would not

leave room for any additions.

23

The last idea considered was building the robot from components. This strategy

would require more work and time to create a working model, but it gave the flexibility

that was required. This was also the only option that has a chance of being under the

$10,000 budget provided.

3.2 Cart Towing Feasibility

Four options were initially considered to tow a medical cart. These options were

pulling and lifting with one pin, pulling with two pins, hooking onto the medical cart, and

grabbing the medical cart from the side. As the ideas developed, grabbing the medical

cart from the side was voted out due to the massive amount of fragile material that would

be present in the arms. The hook idea was seriously considered due to the fact that a

retrofit kit would not be needed, but it was unsure how a medical cart could be moved

backward easily with a hook.

The one pin and two-pin design were seriously considered and designed. The

two-pin design won over the one pin design because of the controllability in turning. The

two-pin design was presented to the customer who expressed doubts in this design’s

ability to produce the amount of torque necessary to turn the medical cart. The customer

favored a design much like the one pin design, except that they wanted the pin to come

up from the robot instead of down from the medical cart. Although this would make

steering a bit tricky, it was worth the cost of being able to travel completely under any

medical cart.

24

3.3 Power System Feasibility

The most beneficial power source was determined to be batteries. These batteries

could either be lead-acid or nickel-lithium. Lead-acid batteries were selected due to their

weight and ability to charge in a short cycle. Nickel-lithium batteries required a very

long amount of charging time and became unpredictable when not charged completely.

They were also very hard to find at large voltages and larger currents needed for the

motors. Lead-acid batteries were available in many voltages and many currents. They

can be charged in a short amount of time and also added weight to the robot for traction.

3.4 Control System Feasibility

The microcontroller for the desired robot required as many inputs and outputs as

possible. The initial microcontroller to be used was the whisker robot controller. This

was found to be inadequate because it did not have enough input or output pins for all of

the necessary sensors. It was also found that the company was not very reliable and the

software was not sufficient. The microcontroller that was instead chosen had more than

enough input and output lines and could control everything necessary. It also had a

development board and sufficient software and support.

3.5 Drive System Feasibility

The drive systems considered for the robot were four separate drive wheels, two

sets of two drive wheels, and two drive wheels with one caster wheel. The four separate

wheel drive option was deemed to be too hard to control and not needed in this

25

application. The scheme of two sets of two drive wheels was considered, but it was

decided that it was not necessary in this application. The drive system that was decided

upon by the team was two drive wheels and one caster wheel. This system made turning

at any radius easy, while the caster wheel supports the weight of the robot and the

medical cart.

3.6 Navigation System Feasibility

The navigation system of the robot was one of the most important parts of the

robot. The choices for navigation were a camera, ultrasonic sensors, and infrared

sensors. The camera was going to be used for the medical cart detection. It was later

realized that the camera could do navigation along with object detection. The ultrasonic

sensors were going to be used as object avoidance, however in the new design of the

robot, there was no room and no need for the ultrasonic sensors.

The microcontroller has two universal asynchronous receive and transmit

(UART) ports. One of the UARTs is used for the camera and the other for the control of

the motors, which led to decide upon the infrared sensors as the navigation system. The

infrared sensors are used in conjunction with a line-following program to navigate the

robot throughout its area of operation. These sensors are very limited in the amount of

space that they can see. Other infrared sensors were also used for obstacle avoidance.

3.7 Communication System Feasibility

The three types of communication systems considered were RF transmission,

infrared transmission, and wired transmission. RF transmission was not eligible, as it is

26

not allowed in a hospital. Infrared transmission was used to communicate between the

robot and the charging station in place of the RF communication. The charging station

will be able to communicate with the washer through a hard-wired connection, and will

pass information from the robot to the washer.

3.8 Cart Detection System Feasibility

Detecting a medical cart may be one of the most challenging aspects of the

design. The object attributes of the medical carts are its existence and its type. The

initial medical cart detection was to be camera technology. With the new design where

the robotic device must fit under the medical cart, the camera needed to be tilted upwards

to see the color blocks. From the color blocks the robot was able to find and travel to the

medical carts. When the robot travels under the medical carts, it used infrared sensors to

determine whether the robot is aligned under the cart and stops the robot when that is

established.

3.9 Retro Fit Feasibility

Retro fitting the medical carts was something that was very important to the

customer. They have many medical carts in hospitals unable to be replaced. The most

efficient solution was to add a bracket to the medical cart for the robot to attach to,

instead of changing the way the medical carts are made. This allows for all medical carts

to be accessed by the robot and by a human. The kit will be attached between the front

wheels. This simplifies the robotic controls as well as cut down on the number of

27

modifications necessary to the medical cart. A retrofit kit is to be made for each type of

cart, due to height and width differences.

3.10 Feasibility Conclusion

The feasibility analysis was defined, refined, and validated by weekly meetings

with Getinge management. Their knowledge of the hospital environment and our

constant brainstorming helped shape the final feasibility model.

28

4.0 Performance Objectives and Specifications

The objectives and specifications define what is needed and how well the solution

will perform. The performance objectives and specifications were customer defined to

meet their market place needs.

4.1 Design Objective

There are a number of design objectives that must be met concluding to the

following:

This product shall be self-guided and fully automated.

This product shall be capable of loading floor-mounted washing machines

with medical carts of various sizes.

There will be two robots per system. RIT will design and prototype the

loading side robot and if time permits, the unloading side robot.

The system must be a stand-alone product that will interface with the Getinge

Model 7800 Floor Loading Cart Washer.

The system must have the capability of detecting the presence of a medical

cart in the load and unload staging areas.

The system must have the capability of detecting the presence of the washer.

The product must identify medical cart type.

The system must have a manual override. (This is important in the case of an

emergency and service.)

This system must be rechargeable.

29

There must be a charging/docking station mounted in the area where the robot

can be recharged.

The robot must also be able to detect the amount of energy left in its fuel cells.

The robot must also be able to charge itself automatically

The medical carts that the robot will be loading into the washer must be

modified so that the robot can safely attach to and navigate them throughout

the hospital.

The system will be configurable to three 7800 Cart Washer models based on

load length.

The robot will be protected (i.e. circuit breakers) to minimize any chance of

fire or smoke generation.

4.2 Performance Specifications

There were certain performance specifications that were met in order for the

project to be successful. The system was designed around these specifications. They are

listed below:

A. NO PIT REQUIREMENTS

The design will not require any pits or holes that must be dug into the

floor of the hospital.

B. EXTERIOR SURFACE-304 STAINLESS STEEL

The exposed exterior surfaces of the robot are to be type 304 stainless

steel with a standard #3 finish. This will match the surface of the medical cart

washers and will be able to withstand the heat and hot water that will be inside

30

of the washer. The exterior surface must also be smooth and free of snag

points to facilitate wipe-down cleaning.

C. 50 POUNDS OF LINEAR FORCE

The robot must provide 50 pounds of linear force in order to move the

medical carts.

D. 100 POUND LOAD

The robot must be designed to operate with a 100-pound load on top.

E. EASILY REMOVABLE COVER

The cover of the robot must be easily removable so that maintenance and

service can easily de done to the robot.

F. SIZE

The robot must be sized for compatibility with healthcare industry

standard case and surgical medical carts. The robot must be able to travel

underneath a medical cart.

G. SERVICE SPACE

No service space is to be required from within or behind the wall mounted

components or from below floor mounted components (no pit).

H. CYCLE TIME

The automated system is to be capable of loading or unloading one

medical cart in one minute or less. Time measured from the robot leaving till

its return to a charging station located no more that three feet (914 mm) from

the washer door opening.

31

I. SUPPLY VOLTAGE

The system must be capable to operate on 120 V, single phase, 50/60 Hz.

J. OPERATED BY GE VERSA-MAX PLC

The automated system is to be operated by a GE Versa-Max

Programmable Logic Controller. The operator interface is a 6” TCP color

touch panel display. Using this touch panel the operator will be able to

accomplish the following:

Start the automated processing cycle

Monitor the process status of automated operations

Stop automated process

Start washer processing with partially loaded chamber

K. OPERATING AMBIENT CONDITIONS

The system must be able to operate under these conditions:

Temperature: 10C (50) to 40C (104F)

Pressure: Atmospheric from 0 to 2000 m (6500ft)

Relative Humidity: 10 to 90 % non condensing

Pollution degree: 2

L. STORAGE AND SHIPPPING

The system must be able to be packed and shipped in the following

conditions:

Temperature: -18C (0F) to 60C (140F)

Pressure: Atmospheric from 0 to 3690 m (12000 ft)

Relative Humidity: 10 to 90 % non condensing

32

Package robot is to survive conditions experienced in the shipping process

without damage.

M. REGULATORY & CODE COMPLIANCE

The product is to be designed to meet requirements of the latest edition of

the following standards:

UL-3101-1, Certified by ETL Testing Laboratories

CSA C22-2 No. 1010.1, Certified by ETL Testing Laboratories

FCC

Seismic requirements per California Administrative Code

N. RELIABILITY AND LIFE EXPECTANCY

With utilities within specified limits and factory recommended

maintenance schedules, the system shall be designed to function properly

without failure or need for repair for a minimum of 12 months from the date

of installation. (3 cycles/hr. x 12 hrs. /day x 6 days/week x 50 weeks/yr. =

10,800 cycles considered 12 month usage)

4.3 Design Practices Used by the Team

There were many design practices that were considered by the team. A list of

these practices are listed below:

Design for Manufacturability- The system was designed so that all needed

parts are readily available and the system shall be easily manufactured.

Design for Safety- The product was designed to comply with all the safety

codes and specifications.

33

Design for Efficiency- The team designed the system to be as efficient as

possible and output as many cycles as possible.

Design for Reliability- The system was designed to be reliable and not to need

constant maintenance and service. It was also designed to meet the 12-month

failure requirement.

Design for Cost- The team designed the robot to be competitive with the

pricing of robots that are already available. It was also designed to have a

manufacturing cost of $10,000.

4.4 Safety Issues

Since this system is made for use in a hospital, there are many safety

measurements that must be met. They are listed below:

Any floor mounted locating and detection devices to be such as to not be trip

hazards to operators.

Audible and visual alarms during any movement of the robot.

System to be capable of detecting obstructions and subsequently stopping

motions. Manual restart is required to resume operation.

Emergency stop switch located on robot and control console.

Automated system to deactivate when 7800 Cart Washer is in “fault mode”.

In the event of a power failure, the control system shall retain current cycle

information for a minimum of 30 days.

34

Upon power restoration, the controller will revert to standby status. If power

loss occurs during a cycle, a cycle not completed message will also be

displayed.

If a detectable system failure or malfunction occurs, the controls will go into a

known safe state.

Failure and malfunction messages shall be displayed in order of occurrence

and printed.

An audible warning shall sound whenever a failure message is displayed.

In the event of an automatic abort resulting in am incomplete cycle, the

operator must restart the system. The unit will not start automatically if a

fault is cleared.

35

5.0 Analysis of Problem and Synthesis of Design

Final designs were created for each component of the robot. After these designs

were made, specific parts were selected to ensure proper assembly. Specific calculations

were performed to determine the requirements of components chosen. The robot

drawings started taking shape as the components were placed inside.

5.1 Housing Design

The outer housing for the robot consisted of the frame assembly and the cover.

All exposed parts were made of type 304 stainless steel with a #3 finish; interior parts

have a 2b finish.

The frame assembly consisted of five sheet metal parts. There was the main

frame that is the base of the robot (Fig. 5.1), which was bent to form most of the sides.

Two small side areas were left open in this frame, which required pieces to be welded

into place to complete the enclosure. A formed bracket that will hold the rear caster

wheel was also welded onto the main frame. The last component was a small bracket

that holds the batteries in position.

Figure 5.1 – Robot Frame

36

The cover (Fig. 5.2) consists of a single piece of sheet metal that is bent to form

the desired shape. It is secured in place by two thumbscrews and supported on four

springs. The springs are designed to hold the cover just above four pressure switches. If

weight is applied to the top cover of the robot, it will automatically shut down as a safety

precaution by tripping the pressure switches.

Figure 5.2 - Housing Top Cover

The housing is punched, drilled and tapped in various locations to accommodate

the numerous sensors and hardware.

5.2 Control System

The control system uses the C8051F120 microcontroller made by Cygnal

(www.cygnal.com). The selection of this microcontroller was based on the requirements

of the video and infrared navigation systems. This controller met or exceeded the

memory requirements with 128k flash memory and 8448 bytes of RAM. Robotic

performance is to be support by a 100 MHz processor. This microcontroller was chosen

primarily for its speed.

37

The other factor playing a role in the selection of the control system was that it

has the required number of I/O ports to accommodate the quantity of sensors required for

the robot to be aware of its environment. The control system consists of the

microcontroller and development board. This enabled the use of the microcontroller

without designing the supporting circuits. Another microcontroller is used in the

charging station for the communication implementation. The specifications of this

microcontroller include 8k flash memory, 768 bytes of RAM and 17 I/O pins with speed

of 25 MHz.

5.3 Pin Mechanism Design

The original design for lifting the pin so it could hitch to the retro fit kit utilized a

screw jack. This design was changed to instead use a cam mechanism. The cam

(Fig. 5.3) was placed directly on the motor shaft and held in place with a key and two ¼-

20 set screws. A standard clevis pin with e-clips secured the hitch pin to the cam while

nylon bushings protected the pivot points. When the motor was activated, the cam turned

and the pin rose. A momentary lever switch was activated when the cam had reached its

final location, either up or down.

Figure 5.3 – Cam

38

Figure 5.4 shows the pin, cam and motor installed in the proper bracket.

Figure 5.4 – Pin Mechanism

5.4 Drive System

The drive system consists of two DC servomotors with encoders (Fig. 5.5). The

gearbox was selected based on its axial load carrying capacity. The concept was to

provide mechanical drive power as simply and efficiently as possible. It is mounted in

the same bracket as the pin mechanism as discussed in section 5.3.

Figure 5.5 – Drive System in mounting bracket

39

Motor

Cam

Pin

Motors

EncodersWheels

Lever switch

The robot had an estimated weight of 71 lbs. Furthermore, the robot had to

support 150 lbs from the medical cart that it is moving. The total weight distribution was

31% on the drive wheels and 69% on the caster wheels. This translated to 22 lbs on the

drive system from the robot and 150 lbs from the medical cart for a total of 172 lbs.

Since the weight was equally distributed between the two drive wheels, each wheel will

have to support 86 lbs. The motor needed an output of 75 watts to move the robot at the

desired speed of one half mile per hour. The motors selected were the Bison 746 DC

servomotors, which had a sufficient power to weight ratio. This motor also mated to a

gearbox appropriately sized to withstanding the 86 lbs that were applied to the bearings in

axial load. The calculations for the weight distribution were conducted using the built in

features of the modeling software, AutoDesk Inventor.

Calculations were also performed for the motor torque and power. It was

specified that the force to push the medical cart was 50 lbs. It was estimated that the

force to push the robot would be 15 lbs. The derivations and calculations for motor

torque and power can be seen in Figure 5.6.

40

Force to push medical cart: 50 lbForce to push robot: 15 lbTotal Force (F): 75 lbSafety (Sf): 1 We will be using the fact that this motor will be only used interminably as a safety.Total Force (Fd): F*Sf = 75 lbOuter Diameter of the wheel (D): 4”

Torque (=

Max Designed Speed (v):

Circumference =

Rotational Velocity ():

Power (P):

Figure 5.6 – Calculation of Drive Motor Torque and Power

5.5 Navigation System

The navigation system consisted of a video camera, the line sensors, and the

sensors for the obstacle avoidance. The video camera served as the main component of

the medical cart detection system. The camera is capable of detecting the color of a

block placed on the cart. Arrays of IR sensors on the front and back of the robot are used

for obstacle avoidance. These sensors allowed the robot to stop before colliding with any

41

potential obstacles and would only be used in crash potential situations. The line sensors

on the bottom of the robot follow the line to and from the charging area and parking area.

Lines cannot be placed inside the washing machine. For this purpose the encoders are

used. The encoders use ticks as a measuring tool for distance. It is easy to determine any

length within the washing machine by counting the number of ticks.

5.6 Mounting Design

With the goal of simplifying the assembly process, the internal

components of the robot were divided into subassemblies. The microcontroller and a

voltage regulator board were piggybacked together and mounted on top of the caster

bracket in the rear of the robot using standoffs. This kept the system from shorting out on

the sheet metal housing.

The first subassembly consists of the two drive motors and the pin mechanism as

seen in section 5.3 and 5.4. This assembly used a 12-gauge sheet metal bracket that was

formed and punched (Fig. 5.7). All motors were mounted to this bracket using 10-32

machine screws. This bracket was secured to the bottom of the housing using ¼-20 pan-

head screws that were inserted from the bottom into tapped holes.

Figure 5.7 – Motor bracket

42

The second subassembly was made up of the rear IR sensor array and a camera.

This assembly was 16-gauge sheet metal bracket that is formed and punched (Fig. 5.8).

The sensors were first mounted into smaller individual sheet metal brackets with 6-32

pan-head screws. These individual brackets were then placed into the larger bracket and

secured with 6-32 pan-head. The camera was secured directly to the center of the large

bracket with 4-40 screws and ¼” standoffs. This subassembly was secured within the

housing using two 8-32 flat-head screws.

Figure 5.8 – Rear Bracket for IR Sensor Array and Camera

The third and final subassembly consisted of the front IR sensor array, a camera,

an IR communications board, and the line tracking sensor array. The front IR sensor

array was secured to a similar type of bracket (Fig. 5.9) used in the rear subassembly but

in the same fashion. The line tracking sensor array was secured to the bottom of this

bracket using 4-40 screws and 3/8” standoffs. This subassembly was also secured into

the housing using 8-32 flat-head screws.

43

Figure 5.9 – Front Bracket for IR Sensor Array and Camera

5.7 Retro Fit Kit

There was a retro fit kit designed that could be applied to various medical carts

(Fig. 5.10). While there would be some modification for each cart, the piece that the

robot attached to was the same on every cart. This piece consisted of a hole in the center

of the bracket to receive the pin mechanism from the robot and a sticker that would be

placed on the cart to be tracked by the robot.

Figure 5.10 - Retrofit Kit

The mounting system attached to the top of the caster wheels on the cart through

the existing holes for the wheel bolts. To attach the retro fit kit, the wheels need to be

removed and then reattached to hold the kit in place.

44

To adapt the kit to larger wire frame carts a bent piece of metal replaced the

straight bracket (Fig. 5.11). This allowed the bracket to be at the same height for all

carts.

Figure 5.11- Wire Frame Kit

5.8 Power Supply Selection

The power supply system consisted of four 12-volt sealed lead acid batteries, at

12 amp hours each. The advantage of lead acid batteries is that the battery can be

recharged when the robot has only a short inactive time because they do not require a

complete charging cycle for continued battery performance. In order to obtain the

required 24 volts to the motors, two sets of 12-volt batteries were wired in series and then

in parallel. The estimated current draw during towing operation is 7 AH. When not

towing a cart, the estimated current draw is 3.2 AH.

In order to deliver power to the various components in the robot, a voltage

regulator board was designed. These voltage regulators provided both 5 and 9 Volts with

1 Amp limit each. The power used from the voltage regulator ran the IR sensors, the

camera, the microcontroller, the IR communication, the speaker, the pin detection

45

sensors, the encoders, and the track sensors.

5.9 The Charging System

The charging system consisted of a Soneil 24 V, 4A battery charger, an IR

communication board and an electrical contact mechanism. The battery charger has the

circuits to properly charge the batteries, as well as maintain this charge over extended

periods without overcharging. The contact consisted of two spring-loaded posts that

protrude from the charger and attach to the metal contacts on the robot.

Figure 5.12 – Charging Station

The communication aspect of the charging station is a gateway from the robot to

the washing machine. The robot sends and receives information to and from the charging

station through an identical IR communication board as on the charging station, which

can be transmitted to the washing machine through a hard wire connection.

46

5.10 Cart Towing

The cart and the robot are attached when contact is made between the pin and the

retro fit kit. The robot tows the cart by this one-pin connection alone.

The robot follows a line from the pick-up area to the washer. Once at the washer

and correctly aligned, it relies only on the digital encoders for distance measurement as

lines were not allowed in the washer.

After the medical cart is positioned in the washer, the robot detaches itself, backs

out from under the medical cart. Upon departure of the washer, the robot either loads a

second cart of the same type or returned to the charger to transmit information.

A major concern was the turning radius of the robot in the hitched position.

Medical cart wheels can be as little as fourteen inches apart between the inside edges. In

order to account for this the robot was approximately 12 inches wide and indented where

the wheels would meet. With this little clearance between the robot and the wheels, the

robot could only rotate 36 degrees off of center when hitched to a cart. This limited the

turning ability and trail of the robot during navigation.

5.11 Cart Recognition

As discussed in the navigation section, the robot used the camera to identify carts

by a colored panel that was placed on the inside of each door. The color signified the cart

type and wash cycle required.

The infrared sensors on the top of the robot detected black lines on the retro fit kit

to determine proper alignment.

47

5.12 Overall design/Analysis Conclusion

......................................The overall concept for the robot is a three-wheel design. The front wheels will

drive the robot while the back wheel will allow motion in any direction. The turning will

be accomplished by the speed differentiation in the drive wheels. The medical cart will

be lifted by cam system. This design can be seen in Figure 5.13 below.

Figure 5.13 – Overall Design of Robot

48

5.13 Software Specifications

The software used for particular tasks was recorded in the format deemed proper

by the customer, as to meet with present company standards. The C language along with

the Keil compiler was used to develop the software that will control the Automated

Loading and Unloading System. The microcontroller that controls the robot is the

C8051F120 from Cygnal Incorporated Products Inc. This microprocessor will supply up

to 100 MIPS throughput and has a 100 MHz system clock. It has 64 I/O ports with 128

KB Flash memory and 256 KB RAM. It has 16 bit counter with 2 clocks and operates

between 2.7-3.6 Volts, with 50mA at 100MHz typical current draw. References to

messages received refer to information being passed to the microprocessor from the

peripheral systems. References to messages sent refer to information being passed from

the microprocessor to the peripheral systems. The microprocessor receives inputs from:

the camera, the infrared sensors, the IR communication board, the track sensors, the line

detection sensors, the encoders, the pin location sensors, the hood depression sensors, and

the dipswitches. The microprocessor send commands to: the h-bridges, the camera, the

IR communication board, and to the display LED’s as indicators or as alarm functions to

control the functionality of the system.

The software written consists of several sub-routines that encompassed the

operations and main functions of the robot. The software includes functions for obstacle

avoidance, encoder positioning, line following, color recognition, and IR communication.

The obstacle avoidance function probed the IR sensors continuously, stopping

movement if there is an obstacle detected in the path of the robot. If an obstacle is

49

present, the robot stops and waits for two seconds and sounds an audible alarm. After the

wait, the IR sensors are checked again for an obstacle. If the obstacle remains in the path

of the robot, that audible alarm sounds again. If the obstacle is still present after six

seconds, the robot will generate an error and a constant audible sound to notify hospital

employees that assistance is needed.

The encoder positioning function keeps a count of the encoder ticks. Each

encoder has two channels: channel A, and channel B. Channel A of each encoder are

used as external interrupts to ensure that no encoder ticks will be missed. Channel B of

each encoder are hooked to I/O pins. When channel A has a rising edge the interrupt is

triggered. The interrupt service routine checks the state of the I/O pin that channel B has

connected to. If channel B is high the counter is incremented, otherwise decremented.

This technique allows the software to keep track of both distance and direction.

To keep the robot traveling in a straight line, the encoders on the left and right

motors are kept within 50 ticks of each other. A correction algorithm will slow the speed

of one motor if it gets ahead of the other. The encoder positioning routine was also used

for distance measurement inside of the washing machine.

The line flowing routine followed a black line on a white background correcting

the robots path when it veered off the straight line. Six phototransistors are used to detect

where the robot is with respect to the line. While following the line, the phototransistors

are checked and the values are returned to the microcontroller. Using these values, the

algorithm decides what action needs to be taken. If the line is moving to the left, the

robot will correct its direction to move left, and visa versa for the right.

50

The camera routine checked for colors set at different priorities and traveled to the

color with the highest priority. The camera communicates to the microcontroller using

UART0 at 115200 baud. The 24.5 MHz internal oscillator on the microcontroller is

multiplied by two to obtain an effective system clock of 49 MHz. Timer three of the

microcontroller is then used along with the system clock to generate a baud rate of

115200. To detect color, the microcontroller sends the track color command along with a

range of red, green, and blue values to the CMUcam. The track color command returns

values where the desired color is located. The data that the camera sends back is split

into arrays for mx (middle of mass in x), my (middle of mass in y), x1 (bottom left

position in x that the color is located), y1 (bottom left position in y that the color is

located), x2 (top right position in x that the color is located), y2 (top right position in y

that the color is located), pixels (the number of pixels of the desired color in the box

created by x1, y1 and x2, y2), and confidence (how well the color is seen). It uses the

position of the middle of mass, and from that deciphers if it needs to turn left, right, or go

straight. The robot navigates to the color while simultaneously tracking the position of

the color. Once the color has been reached, the robot is ready to move underneath the

cart and engage the tow-pin.

The IR communication routine transmits and receives specific codes to and from

the robot. The codes are four bit arrays that consist of ones and zeros. When a new

transmission has been received, the valid transmission pin is driven high by the IR

communication board. The microcontroller detects this change and then reads the four-

bit code that has been sent, and acts accordingly. The software on both the robot and the

51

charging station act in the same fashion, but have minor changes in code due to the

difference in microcontrollers.

The microcontroller communicates with the drive motors through the motor

controller using UART1 at 9600 baud. The system clock that was generated for the

camera routine is again used along with timer one to create a baud rate of 9600. The

motor controllers allow control of direction, and speed that varies from zero to nine (zero

being stop, nine being fastest.) The following table shows the commands used to control

the motor control:

52

Command Parameter #

FF# Both Motors Forward

0-9 (0=Stop; 9=Full Speed)

BB# Both Motors Reverse

LF# Left Motor Forward

LB# Left Motor Reverse

RF# Right Motor Forward

RB# Right Motor Reverse

FB# Left Motor Forward, Right Motor Reverse

BF# Left Motor Reverse, Right Motor Forward

STP Stop Both Motors

NASLT Stop Left Motor

SRT Stop Right Motor

ABT Abort Current Command and Reset Controller (all motors stopped)

TR# Set Ramping Delay

0-9 (0 = 50 ms; 1 = 100 ms;

2 = 200 ms…

9 = 900 msTable 1: Motor Control Commands

The pin motor is controlled using two I/O pins of the microcontroller. Since the

speed of the pin motor will not need to vary, two pins of the microcontroller are used to

control the direction of the motor. The following table shows the states of the pins that

are required to control the direction of the pin motor:

53

Condition F BMotor Off 1 1Motor Forward

0 1

Motor Reverse

1 0

Table 2: Pin H-Bridge Conditions

The pin assembly uses two proximity sensors to detect the position of the pin.

These proximity sensors are connected to I/O pins on the microcontroller. The sensors

are normally high, so when they switch to low that signifies that the pin is in the desired

position. Thus, the microcontroller sends the signal to pin motor controller to stop the

pin motor.

54

6.0 Test Protocols

A complete set of test protocols were developed in conjunction with the customer.

The protocols were designed to test the operation and performance of the robot as it

pertained to the specifications given at the beginning of the project. These tests checked

for things such as proper weight bearing response and obstacle detection distance.

Addition tests were also added for next generation robots. A complete list of the

protocols and the results are located in Appendix F.

55

7.0 Budget

The team’s budget is $10,000 provided by Getinge. This money is to be used for

building and testing of the robot. According to the Bill of Materials, the amount spent is

less than $5000. This is a good projection that the entire system can be manufactured for

under $10,000. The budget includes all purchased parts for one robot. Getinge made the

manufactured parts and their cost is yet to be calculated.

56

8.0 Future Plans

As the design phase progressed, many problems hampered the robot and the team.

There was a serious lack of reliability in some of the components that kept many test

from being performed. The experimentation that was conducted led our team to many

conclusions about the best options for future prototypes of the system. The following are

suggestions of possible improvements on the existing design:

Line following using the camera due to the reliability of the IR tracking

sensors

Use of different H-bridges

o PWM transmission instead of serial

o More control

Use of different microcontroller

o More interrupts

o More UARTs

Additional cameras

o Side mounted for cart identification

Cooling fans located on the sides of the robot to keep the processors at a more

suitable temperature

57

9.0 Conclusion

The senior design team has completed the full design cycle. The first six design

processes, including the needs assessment, project objectives, project specifications,

concept development, feasibility assessment, the analysis and synthesis of design, and the

preliminary design documents were created during the first quarter of the project.

During the second quarter of the project, the team fabricated, tested, and reworked

the robot. The present design is a proof of concept; a great tool that in the future can be

used to take the robot to market.

The team developed four concepts and assessed their feasibility. The concepts

include different sizes, attachment methodology and communication. Although each

concept compared well with the baseline design, the team decided to proceed with the

specified design discussed. This decision was based upon the results of the feasibility

analysis, the constraints, and the company’s requirements.

An analysis of several aspects of the robot was completed. A variety of

calculations were done to determine the pulling strength due to frictional effects and

weight. Two flow charts were developed showing the robot’s steps on every move and

communication. Finally, an analysis was done to select the microcontroller that will be

used to control the movements of the robot.

During the spring quarter, the team fabricated, tested, and redesigned the robot.

The software and the hardware were designed in parallel and integrated. Although there

were a few hurdles, each leap gave the team further knowledge of the robot and their

respective fields. The robot created is the first step to creating an industry-leading robot.

58

References:

Product Specification: Model 2040 Automated Loading and Unloading System, Specification Number: 360246, Getinge Sourcing. LLC.

Hazard Analysis, Series 7800/7900 Health Care Washers, Specification Number: 360231, Getinge Sourcing. LLC.

Design Control Procedure, 8/04/03, QSP # 110, Rev. E, Getinge Sourcing. LLC.

Data and Specifications, Model 7800 Series Floor Loading Cart Washer, Getinge USA.

http://www.motioncontrol.com

http://www.maxonmotorusa.com/

http://www.micromo.com/

http://www.superdroidrobots.com/trekker_drive.htm

http://www.oopic.com

http://www.robotcombat.com/marketplace_motors.html

http://www.lynxmotion.com

http://www.robotics.com

http://www.mobilerobots.com

http://www.activrobots.com/

http://www.engr.iupui.edu/me/courses/fproject.shtml

http://www.atmel.com/dyn/resources/prod_documents/doc1253.pdf

http://microcontrollershop.ucpros.com/product_info.php?products_id=154

http://www.keil.com/mcb517/

http://eet.etec.wwu.edu/CPU12/PODInstrs.pdf

http://www.post-gazette.com/businessnews/20011025aethon1025bnp2.asp

59

http://www.irobot.com

http://www.aai.ca/robots/index.html

http://www.robotbooks.com

http://www.medtronic.com/semi/products/microcontrollers.html

http://microcontroller.com/default.asp

http://www.samsung.com/Products/Semiconductor/common/product_list.jsp?family_cd=LSI060101

http://www.robotstorehk.com/sensor.html

http://www.aethon.com/

http://www.angelusresearch.com

60

List of Appendices

Appendix A: Software FlowchartsAppendix B: Sample Storage LayoutAppendix C: Bill of MaterialsAppendix D: Technical DrawingsAppendix E: Test Protocol

61

Appendix A: Software Flowcharts

Appendix B: Sample Storage Layout

Appendix C: Bill of Materials

Appendix D: Technical Drawings

Appendix E: Test Protocols

QTY DESCRIPTION VENDOR Cost per item

Total Cost

1 BOARD, IR COMMUNICATION, CHARGER MANUFACTURED $20.00 $20.002 CONDUCTOR, CHARGER MANUFACTURED NA NA1 COVER, CHARGER SST MANUFACTURED NA NA1 COVER, HIGH VOLTAGE, CHARGER SST MANUFACTURED NA NA1 PIN, ALIGNMENT CHARGER-ROBOT MANUFACTURED NA NA1 ASSY., RETROFIT KIT MANUFACTURED NA NA1 PLATE, RETROFIT KIT LOWER PORTION MANUFACTURED NA NA1 PLATE, RETROFIT KIT UPPER PORTION MANUFACTURED NA NA8 ASSEMBLY, SENSOR MANUFACTURED NA NA1 ASSEMBLY, WELD, FRAME MANUFACTURED NA NA1 ASSY. OVERALL MANUFACTURED NA NA1 ASSY., BACK PLATE MANUFACTURED NA NA2 ASSY., CHARGING CONTACT MANUFACTURED NA NA1 ASSY., FRONT PLATE MANUFACTURED NA NA1 ASSY., MOTOR MANUFACTURED NA NA1 BOARD, IR COMMUNICATION, ROBOT MANUFACTURED NA NA1 BOARD, VOLTAGE MANUFACTURED NA NA1 CAM, LOCK PIN, ROBOT 300 SST MANUFACTURED NA NA2 CONDUCTOR, PLATE MANUFACTURED NA NA1 COVER, ROBOT SST MANUFACTURED NA NA2 COVER, ROBOT SST MANUFACTURED NA NA1 COVER, ROBOT SST MANUFACTURED NA NA1 COVER, CHARGER SST MANUFACTURED NA NA1 MOUNT, CASTER, ROBOT SST MANUFACTURED NA NA1 PIN, LOCK, ROBOT SS MANUFACTURED NA NA8 PLATE, PIVOT, IR SENSOR, ROBOT SST MANUFACTURED NA NA1 PLATE, BATTERY, ROBOT SST MANUFACTURED NA NA2 PLATE, CAMERA, ROBOT SST MANUFACTURED NA NA

1PLATE, MTG, CAMERA/ SENSOR, REAR, ROBOT SST MANUFACTURED NA NA

1PLATE, MTG, CAMERA /SENSOR, REAR, ROBOT SST MANUFACTURED NA NA

1 PLATE, MTH, H-BRIDGE, ROBOT SST MANUFACTURED NA NA3 CAMERA, CMUCAM ACRONAME $109.00 $327.00

2CONTROLLER, DUAL BI-DIRECTIONAL 8AMP MOTOR HVW TECHNOLOGIES $84.95 $169.90

4 HOLDER, NUT, LED RADIOSHACK $1.29 $5.164 LED Holder RADIOSHACK $0.00 $0.001 MICROCONTROLLER, ADAPTER SEE WITH MICRO $0.00 $0.00

1MICROCONTROLLER, C8051F120 128K FLASH 100PIN DIGIKEY $99.00 $99.00

1MICROCONTROLLER, C8051F330 8K FLASH 20 PIN 8K FLASH 20 PIN DIGIKEY $49.00 $49.00

8 SENSOR, IR, Long range GP2Y0D02YK DIGIKEY $15.49 $123.923 SENSOR, TRACK LYNX MOTION $19.95 $59.85

1BEARING, PLAIN SLEEVE, 1/2" SHAFT, 19/32 OD 1" L MCMASTERCARR $11.55 $11.55

2BEARING, PLAIN SLEEVE, 1/4" SHAFT, 5/16" OD MCMASTERCARR $4.52 $9.04

4BEARING, PLAIN SLEEVE, 1/8" SHAFT, 1/4" OD, 1/4" L MCMASTERCARR $0.65 $2.60

1BEARING, PLAIN SLEEVE, 1/2" SHAFT, 19/32 OD .75" L MCMASTERCARR $9.53 $9.53

8 NUT 6-32, SST MCMASTERCARR $0.03 $0.244 NUT, 1/4-20   $0.03 $0.124 NUT, 1/4-20 SST MCMASTERCARR $0.03 $0.12

10 NUT, 4-40 SST MCMASTERCARR $0.01 $0.071 PIN, CLEVIS, .5"ODx2", WITH E-CLIPS SST MCMASTERCARR $4.49 $4.49

2RETAINER, PUSH, 5/16" Screw, 15/16" OD, .083" OAL H MCMASTERCARR $0.04 $0.08

19 SCREW 4-40 x 1-4 SST MCMASTERCARR $0.06 $1.124 SCREW, FLAT HEAD, 4-40 x 7/16 SST MCMASTERCARR $0.02 $0.07

10 SCREW, FLAT HEAD, 8-32 x 3/16 SST MCMASTERCARR $0.03 $0.3214 SCREW, PAN HEAD 10-32 x 1/2 SST MCMASTERCARR $0.14 $2.024 SCREW, PAN HEAD 4-40 x 1 SST MCMASTERCARR $0.10 $0.408 SCREW, PAN HEAD 6-32 x 1 1/8 SST MCMASTERCARR $0.12 $0.988 SCREW, PAN HEAD, 1/4-20 x 1/4 SST MCMASTERCARR $0.09 $0.732 SCREW, PAN HEAD, 4-40 x 3/8 SST MCMASTERCARR $0.07 $0.13

32 SCREW, PAN HEAD, 6-32 x 1/4 SST MCMASTERCARR $0.02 $0.564 SPACER, #4 x 1/2" DIGIKEY $0.14 $0.562 SPRING, 302 SS 5/16"x1", .029" WIRE MCMASTERCARR $1.03 $2.07

16 STANDOFF, 1/4" SNAP M/M DIGIKEY $0.21 $3.428 STANDOFF, 4-40 x 3/8 M/F DIGIKEY $0.31 $2.484 STANDOFF, 4-40 x 1 M/F DIGIKEY $0.31 $1.257 STANDOFF, 4-40 x 1/4 M/F DIGIKEY $0.31 $2.145 STUD, 1/4-20 x .875 STANDARD $0.13 $0.634 WASHER, #4 MCMASTERCARR $0.02 $0.074 WASHER, NYLON 1/4" MCMASTERCARR $0.03 $0.131 CASTER, 1 1/2" SST BALL CASTER SUPPLY $45.00 $45.002 ENCODER, SCREW MOUNT BISON $66.65 $133.302 FAN, 40 X 20MM 24VDC 24v 6CFM DIGIKEY $10.29 $20.582 FAN, COVER, SERIES 400 EBM INDUSTRIES $1.29 $2.581 MOTOR LEFT SIDE DRIVE BISON $189.20 $189.201 MOTOR, RIGHT SIDE DRIVE BISON $189.20 $189.201 MOTOR, PARALLEL SHAFT BISON $186.84 $186.84

2WHEEL, 4"ODX1.5"WD, 3"CORE 60A POLYURETHANE   $45.55 $91.10

2 BATTERIES, 12V 7AH BATTERYSTUFF.COM $27.00 $54.002 BATTERY, HELIOS 12V 12AH BATTERYSTUFF.COM $27.29 $54.58

1CHARGER, 24 VOLT 4 AMP CONSTANT CURRENT BATTERYSTUFF.COM $123.75 $123.75

1RECEPTACLE, PANEL MOUNT, 15 Amps @ 125 VAC MCMASTERCARR $0.94 $0.94

1 SWITCH, LEVER SEALED 5A DIGIKEY $4.25 $4.251 SWITCH, NUT, ON/OFF RADIOSHACK $0.00 $0.004 SWITCH, NUT, PRESSURE ? $0.00 $0.002 SWITCH, NUT, RESET RADIOSHACK $0.00 $0.00

C1

1 SWITCH, ON/OFF POWER RADIOSHACK $2.29 $2.29

1SWITCH, ROCKER, STANDARD SIZE, SPST, 15 AMPS MCMASTERCARR $3.43 $3.43

2SWITCH, SIMULATED ROLLER SWITCH V3 SERIES DIGIKEY $1.83 $3.66

4 SWITCH, TOP WEIGHT ? $2.43 $9.722 SWITCH, Normally-closed Momentary Switch RADIOSHACK $2.29 $4.58

     Total Cost

$2,029.76

Note: The price of Manufactured parts was not accounted in the total cost.

C2