ENME Final Report -HAndcycle Motor

8/4/2019 ENME Final Report -HAndcycle Motor

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Power Assist for a Handcycle

Team Number 13

Project Final Report Document

Document History

Date Author Version Change Reference

April 1, 2011 Greg Fry A Created document added Verification

and Testing

April 5, 2011 Darcy Power B System Archetecture

April 7, 2011 Kenny Wang C Design Elements

April 9, 2011 Mahmuod Elfouly D Project Management

April 12,

2011

Stephen McKinney,

Manuel Hopf

E Added Specifications, integration, final

Editing

Document Properties

Item Details

Document Title Project Final Report

Author Mahmoud Elfouly, Greg Fry, Manuel Hopf, Stephen McKinney,

Darcy Power, Kenny Wang

Creation Date April 1, 2011

Last Updated April 12, 2011


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12/4/2011 i Power Assist for Handcycle

List of Tables

Table 1 - Concept Evaluation Matrix ............................................................................................. 11

Table 2 - Coefficient Values for Tires on Different Surfaces ......................................................... 14

Table 3 - Resulting Energy Storage for Several Common Battery Configurations ........................ 20

Table 4 - Expected Full Discharge Run Times Under Full Power ................................................... 21

Table 5 - Expected Cost of Various Battery Sizes .......................................................................... 21

Table 6 - Functionality Tests Performed........................................................................................ 27

Table 7 - Results for the Speed Test .............................................................................................. 28

Table 8 - Results of the Flat Surface Brake Test Table 9 - Results of the Incline Brake Test .. 29

Table 10 - Thottle Setting vs. Run Time ......................................................................................... 30

Table 11 - Risk analysis table (10 indicates high risk or probability and 1 indicates low risk or

probability) .................................................................................................................................... 30

Table 12 - Estimated Bill of Materials ............................................................................................ 38

Table 13 - Actual Bill of Materials .................................................................................................. 38


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12/4/2011 ii Power Assist for Handcycle

List of Figures

Figure 1 - Design Schematic ............................................................................................................ 4

Figure 2 - Clustered Design Schematic ............................................................................................ 5

Figure 3 - Location of the Battery on the Hand Cycle ..................................................................... 6

Figure 4 - Throttle and Cruise Control Mounted on Hand Cycle ..................................................... 7Figure 5 - Disc Brake and Hub Motor Mounted on Hand Cycle ...................................................... 7

Figure 6 - High Level Functional Diagram ........................................................................................ 8

Figure 7 - Energy Storage Classification Tree .................................................................................. 8

Figure 8 - Conversion to Kinetic Energy Classification Tree ............................................................ 9

Figure 9 - Speed Control Classification Tree .................................................................................... 9

Figure 10 - Power to Wheel Classification Tree .............................................................................. 9

Figure 11 - Braking Devices Classification Tree ............................................................................. 10

Figure 12 - Functional Component Combinations......................................................................... 10

Figure 13 - Free Body Diagram of Hand Cyclist ............................................................................. 13

Figure 14 - Disk Drake Tab ............................................................................................................. 15

Figure 15 - Attached Disk Brake System ........................................................................................ 15

Figure 16 - 250 Watt Hub Motor ................................................................................................... 16

Figure 17 - Power Required to Propel Various Bicycles ................................................................ 17

Figure 18 - CAD Drawing of Hub Motor ......................................................................................... 18

Figure 19 - Integrated Hub Motor ................................................................................................. 18

Figure 20 - Final Battery Selection ................................................................................................. 22

Figure 21 - Drawings for Manufacture for Disk Brake Tab ............................................................ 22

Figure 22 - Disk Tab After Water Jet Cutting ................................................................................. 23

Figure 23 - Tab Welded to Fork ..................................................................................................... 23

Figure 24 - Disassembled Wheel ................................................................................................... 24

Figure 25 - Spoke Lacing Pattern ................................................................................................... 25

Figure 26 - The Rear of the Cycle With Both Systems Installed .................................................... 27

Figure 27 - Work Breakdown Structure ......................................................................................... 35

Figure 28 - Schedule ...................................................................................................................... 36

Figure 29 - Gantt Chart .................................................................................................................. 37
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12/4/2011 iii Power Assist for Handcycle

List of Symbols

Symbol Definition Unit

m Mass kgg Acceleration due to gravity Angle degrees

F Force Newton

W Work Watts

Density Cd Aerodynamic shape factor Dimensionless

v Velocity m/s


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12/4/2011 1 Power Assist for Handcycle

Project Final Report (PFR)

Design Methodology and Application (ENME 538 / ENMF 512)

Fall 2010 / Winter 2011

1.0 Project Overview

1.1 Background and Overall ObjectiveThe client Ryan Yeadon is an athletic paraplegic who works for The City of Calgary. He enjoys

riding his hand cycle, but tends to have major difficulties climbing hills. These difficulties are most

strongly associated with the fact that Ryan has no muscle function from his trunk down, and he is

using only his shoulders and arms to power his hand cycle. Since the arms and shoulders were

never intended for load carrying and moving around on, they are generally much weaker than the

legs and hips. For this simply anatomical reason, it can easily be seen that using the shouldersand arms to power a cycle up a hill could be very difficult and tiresome. Aside from the difficulties

with hills, many paraplegics wear out their rotator cuffs due to overuse and as a result are

eventually required to use electric wheel chairs. Being that Ryan is an athletic person, he has no

desire to ever be constrained to an electric wheelchair and therefore wants to find any way to

avoid this common injury. Finally, the design will be customized to Ryans hand cycle, the Top

End Excelerator XLT.

The objective of this project is to make it easier for Ryan to climb hills on his hand cycle. He

currently gets worn out after one or two hills, and therefore must reduce the length of his ride. By

reducing Ryans energy consumed going up hills, the design will allow him to enjoy longer and

more thrilling rides. This design will also reduce the potential for future rotator cuff injuries; by

reducing the energy used going up hills, it reduces the overall strain on the rotator cuffs, thereforereducing the potential for injury.

Further to the central objective of the project, to provide assistance to Ryan in climbing hills on his

hand cycle, he has informed us that his current braking system is very unreliable. Since the

design will add power to Ryans hand cycle, one side objective is to improve his braking system.

1.2 RequirementsThe following project requirements were derived from the clients desires and expectations, legal

requirements, and requirements for safe operation

The design must be specific to the hand cycle model Top End Excelerator XLT

The client must be able to turn the power assist on and off.

The design must be capable of powering the hand cycle up hills throughout a 1 to 2 hour

ride.

The design must be legal.


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The entire power assist system must be light enough that it will have minimal impact on

transport and unpowered use of the handcycle

The bulk of the system weight should be attached to the rear of the hand cycle

1.3 Design Specifications

The following specifications represent minimum requirements that the project must be designed

to adhere to. Note that all requirements have been developed by the project team to fulfill the

project definition.

1.3.1 Project Specifications:

SP-PJCT-01 REV.1 (IFU) General Design

1. The finished product shall operate safely. Proper engineering design shall be

used to ensure the safety of the operator and public.

2. Risk shall be eliminated when practical and otherwise managed using

properly engineered controls. Personal protective equipment will only be

used as a last barrier to injury.

3. The client shall be made aware of all potential hazards and controls. He will

then be asked to verify his acceptance of all risk and liability associated with

using the product.

4. The design shall comply with all legal requirements for electronic bicycles.

5. All changes to the existing hand cycle will be properly managed with

emphasis on detecting any potential unforeseen consequences.

6. Stability and the ability to effectively control the hand cycle are critical and

any concept which compromises these aspects shall not be seen as asolution.

7. During design, benefits to both powered and unpowered operation shall be

considered.

8. The design shall be sufficiently robust as to provide reliable operation for a

period of at least three years from initial operation. During this period only

routine maintenance, and not the replacement of capital components (unless

otherwise specified), shall be required.

9. When applicable both capital and operating cost shall be considered in order

to reduce total cost over the product life.

10. The product shall conform to the OH&S noise levels specification for

continuous exposure without hearing protection.

11. The total weight added to the handcycle during this project shall be less than

30lbs.

12. The powered handcycle shall be able to legally operate in all the areas it can

while unpowered.


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1.3.2 Component Specifications:

SP-CPNT-01 REV.2 (IFU) - Motor

1. A 160lbperson shall be able to reach a speed of at least 25km/h but not in

excess of 32km/h when traveling on smooth pavement with no incline using

motor power alone..

2. The motor shall have an efficiency of at least 90%.

3. The motor shall have an average life expectancy of at least five years without

major repairs before replacement under the expected usage.

4. The motor shall automatically stop providing power when the brakes are

applied.

SP-CPNT-02 REV.2 (IFU) - Battery

1. The battery shall be able to provide sufficient power to the motor so that it

can operate under full power for a minimum of 45 minutes in new condition.

2. After 1000 cycles with full charge and depletion, at least 75% of the initial

power capacity shall be retained.

3. The battery shall be capable of fast charging in 4 hours or less.

4. In order to accommodate the Canadian climate the battery shall be capable

of operating in a temperature range of -5C to 35C and shall be weather

proof. Preference will be given to batteries that can operate under a wider

variety of conditions.

5. Total battery weight shall not exceed 14lbs.

SP-CPNT-03 REV.2 (IFU) - Brake

1. The hand cycle shall be capable of stopping at least as quickly as a typical

bicycle under the same conditions. This represents a value of 5m/s2

on dry

pavement.

2. The brakes and attachments shall be sufficiently robust as to ensure that any

operating stresses will not cause failure.

3. The brake system shall last at least one year without replacing any

component, and two years without replacing rotors. The caliper body shall

remain functional for at least five years.

SP-CPNT-04 REV.0 (IFU) Control Systems and Electronics

1. All electronic components shall be weather proof.

2. The throttle shall have a toggle switch or cruise control to allow for hand

pedaling and steering while the motor is in use.


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3. An electronic horn producing sound of at least 100 decibels shall be included

and easily accessible during operation.

2.0 System Architecture

2.1 Selected DesignThe schematic of the design outlines how the different elements of the design interact with one

another. As can be seen in the diagram, the battery, throttle, cruise control and kill switch all

attach to the control box, which acts as the central hub for the components. The control box then

releases energy to the hub motor, which in turn rotates the front wheel. Meanwhile, the brake

lever will engage both the disc brake and the kill switch, which will simultaneously kill power to the

hub motor and dissipate energy from the front wheel.

Figure 1 - Design Schematic

In the clustered design schematic, elements are assigned to different chunks which allow better

visualization of the final product. In this clustered schematic, elements are assigned based on

similarity of function and physical location on the hand cycle.


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Figure 2 - Clustered Design Schematic

In figure 2, we see that the battery is clustered on its own. This is because the battery has the

unique function of storing and providing power, and its location on the rear of the cycle separates

it from the rest of the elements. Another cluster includes the throttle, cruise control, control box,

kill switch and brake lever. These elements are all used to control the design, and are all in close

physical proximity near the middle of the cycle. The last cluster is made up of the hub motor, the

front wheel of the hand cycle, and the disc brake. All of these elements are involved in the

transfer of energy to the hand cycle, and are all situated at the front of the cycle.

2.2 ComponentsFinally, we will give an understanding as to how all of these components fit onto the hand cycle

and where the components are located. There is a large space behind the seat where the battery

is located, mounted on the two parallel black bars. This location was chosen because the batteryis the largest component in our design, and the rear of the hand cycle had the most available

space. Also behind the seat is the control box, which needed to be in a central location and out of

the way of any of the other components.


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Figure 3 - Location of the Battery on the Hand Cycle

For the control system of the throttle, cruise control and brake lever, these are located on the bars

that come out to the side from under the seat. The throttle and cruise control are mounted on the

same side of the hand cycle, and only one hand is needed to operate the two components. This

ensures that our client never has to take both hands off of the hand cranks, and retains the ability

to steer at all times. The kill switch is built into the brake lever, and did not need to be mounted

separately. All of these control components are easy to reach and use, which provides a

comfortable, safe ride for our client.


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Figure 4 - Throttle and Cruise Control Mounted on Hand Cycle

Finally, the motor hub and disc brake system replaced the client's old wheel hub and braking

system on the front tire. All of the components in this area were installed making sure that the

client's leg rest area was not compromised, and that none of the components made mounting the

cycle inconvenient.

Figure 5 - Disc Brake and Hub Motor Mounted on Hand Cycle


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3.0 Development and Assessment of Design AlternativesConcept development and assessment was explained in detail in the Conceptual Design

Document and only major components and notable changes will be included here. Based on the

following functional diagram of the project a large number of concept possibilities were initially

generated.

Figure 6 - High Level Functional Diagram

The ideas that arose from the initial brainstorming are outlined below. The ideas have been

organized into classification trees by critical functions. These trees represent a robust but non-

inclusive list of all concepts generated. Any idea that was considered to be fully implausible after

only a brief team discussion is not included in this report.

Figure 7 - Energy Storage Classification Tree


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Figure 8 - Conversion to Kinetic Energy Classification Tree

Figure 9 - Speed Control Classification Tree

Figure 10 - Power to Wheel Classification Tree


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Figure 11 - Braking Devices Classification Tree

The concepts to be considered further were reduced significantly when feasibility was considered.

After a preliminary feasibility screening was completed, there were various options available in

each functional category and further analysis was required to progress. The most feasible power

train components are tabulated below and sorted by function. Some logical combinations are

highlighted and it should be noted that many components are mutually exclusive such as

powering a 2-stroke engine with a lead acid battery.

Figure 12 - Functional Component Combinations


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In order to determine the most likely optimal combination a concept evaluation matrix was created

using weighted values comparing key features. This table has been updated since the CDD in

order to reflect new learnings.

Table 1 - Concept Evaluation Matrix

2-Stroke Engine Additional Notes

A gas powered 2-stroke 50cc engine was originally considered as a strong concept. The engine

could produce 750W-1500W continuously for hours depending on the gas tank size and the cost

would be around half of a LiFePO4 system. However, he legal requirements associated with this

concept are prohibitive. When fitted with the engine, the hand cycle legally becomes a moped (as

opposed to an electric bike) and must abide by Alberta moped laws. These laws include not

riding on pathways, obtaining a license, and having reflectors, mirrors, brake lights and turn

signals.

Value We ighted V al ue Value Wei ghte d Val ue Value Wei ghte d Value

Cost 20 1 20 3.5 70 5 100

Weight 10 3 30 1 10 4 40

Reliability 20 4 80 3 60 3 60

Power 15 3 45 2 30 4 60

Ease of Operation 15 5 75 4 60 2 30

Ease of Installation 5 4 20 3.5 17.5 2 10

Rider Comfort 20 5 100 4 80 1 20

Safety 25 4 100 3.5 87.5 3 75

Cleanliness/Aesthetics 5 5 25 4 20 1 5

Total 135 34 495 28.5 435 25 400

Gas PoweredElectric Hub (Lead Acid)Electric Hub (LiFePO4)Concideration Weight


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4.0 Design to SpecificationsThe project specifications were created by the project team in response to customer needs. They

are technical requirements which translate the generally vague customer requirements into

measurable objectives. The goal during this project was to minimize the total cost while meeting

all of the design specifications. This was done in both the conceptual design and in the selection

of the parts and vendors used to implement the design. The testing section will describe in detailhow the performance was tested to ensure compliance. The general project specifications were

to show the key goals of the project. These requirements such as safety, proper design

procedure and overall robustness were implemented throughout the entire project.

4.1 Implementation in DesignIn the conceptual design, there were limitations to the practical concepts due to the specifications.

For instance, a gas motor would have added additional legal requirements and limited the areas

the handcycle could operate. The general project specifications outline the key considerations in

the design. Unlike the component specifications, they are not always quantifiable but they are

designed to make explicit the key considerations for the project.

4.2 Implementation in Part/Vendor SelectionThe performance characteristics (run-time, power, etc.) of the overall system are a key

component of the specifications. When searching different vendors for components, first all parts

were found that met the specification, then they were ranked according to price. The vendor that

had the lowest total price was used to purchase the components. When evaluating the prices,

shipping and handling was included in each instance. This added a significant cost when parts

were ordered from different suppliers because they would have to be shipped separately.

5.0 Braking System

5.1 Braking DescriptionDuring our first meeting with Ryan, he mentioned that the current brake system on his hand cycle

was unreliable and he was frequently having trouble stopping. The brake on the hand cycle was

known as a single pivot caliper brake, which is known to have a low mechanical advantage and

problems in wet weather. The weather problems stem from having the braking surface very close

to the ground, which allow the surface to become very wet during or after rainy weather. While

the rims are wet, braking power can be reduced by 50-90%. [2] Attaching a mechanical disc

brake to Ryans hand cycle gave him a higher mechanical advantage, and also raised the braking

surface away from the road, allowing it to stay dryer, and thus stay more effective.


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5.2 Braking DesignIn order to determine the force generated by the brakes, different scenarios (speed, slope,

stopping distance) had to be examined. To determine this braking force, the following system

was made: A hand cyclist riding down a hill of slope . The mass of the hand cycle and rider can

be considered as m. The hand cyclist is moving down the hill at speed v, and must stop within a

distance d.

Now, from conservation of energy, we know:

We know that W input is the work done by gravity in the direction parallel to the slope, while Woutput

is the work done by the braking force FB. Work is simply F*d and Vf = 0.

Equation becomes:

h is simply d*sin, and FB is simple m*aB, where aB is the acceleration generated by the brakes.

Dividing through by m*d gives:

()

Using this formula for acceleration and Matlab, different values for acceleration due to the brakes

were calculated. In the program, the speed varied from 25km/h to 60km/h and the slope of thehill ranged from 0-12% in 0.5% increments. According to a textbook on bicycling science, the

minimum stopping distance (in metres) for a stable vehicle with adequate braking power and no

danger of the rear tires lifting is governed by the equation:

( )

The following assumptions are made in order to

simplify the calculation:

Wheels continue to roll while braking

(i.e. tire friction is negligible)

The effect of drag while braking is

negligible

Energy is not lost

Figure 13 - Free Body Diagram of Hand Cyclist


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where CA and CR are the coefficients of adhesion and rolling resistance.[2]

Using tabulated values

(see figure 1) for CA and CR, the minimum stopping distance at the different speeds was

calculated. Based on these minimum values, three different stopping distances (6m, 10m and

17m) were chosen for different values of speed. The textbook stresses that these are minimum

values, and in reality any deceleration over would flip a cyclist over the handlebars, andrecumbent bikes (such as our hand cycle) are capable of a deceleration of 0.8g, or

with

a typical tire to road friction coefficient of 0.8. Refer to appendices A and B for the Matlab

program to calculate the brake acceleration and a table of the values of braking acceleration.

Table 2 - Coefficient Values for Tires on Different Surfaces

The force that a disc brake caliper can produce is dependent on the geometry of both the caliper

and the brake lever, which provide a mechanical advantage for the rider to engage the brakes.

Hayes, a manufacturer of bicycle brakes, states that on average a mechanical disc brake caliper

has a clamping force of about 1200 lbs (or 5350N).[3]

Sintered brake pads used in bicycle brakes

have dynamic friction coefficients ranging from 0.35 to 0.42.[4]

Using these values, along with a

standard 185mm diameter rotor, we can determine if the disc brakes will have enough force tosuitably slow the hand cycle.

This is the force that the brake pads can apply on the 185mm diameter rotor. Knowing Ryans rim

is 520mm in diameter, we can determine the braking force that the tire will output onto the road.

Using this stopping force and the estimated weight of the system, we can determine the

deceleration.

This value comes very close to our accelerations computed using the minimum stopping

distance, and also means that Ryan will be able to stop roughly 27% quicker than a cyclist

travelling at the same speed.


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5.3 Final DesignAccording to the design principles illustrated above, the final design used a standard bicycle disc

brake purchased from Sport Chek with a 180mm rotor. The rotor was very easily attached to the

hub motor, however, in order to attach the calliper, a machined tab needed to be welded onto the

fork as shown in figures 14 and 15 below.

Figure 14 - Disk Drake Tab

Figure 15 - Attached Disk Brake System

Based on testing, the disc brake stops the hand cycle within 3m at 25km/h on a flat road. Theperformance meets and exceeds the design criterion.


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6.0 Hub Motor

6.1 Hub Motor DescriptionA hub motor was chosen to provide the electrical to mechanical energy conversion needed to

power the hand cycle. The hub motor that has been selected has a 250W power rating and is

rated to run on 24V. It has been integrated into the hand cycles front tire, replacing the existinghub. An image of the hub motor can be seen below in Figure 16.

Figure 16 - 250 Watt Hub Motor

6.2 Hub Motor DesignIn order to determine the most suitable power rating for the hub motor that had to be integrated

into the hand cycle, some calculations were carried out. This was needed to see what speeds

would be achieved with different power motors on flat grounds and on hills.

The project requirements call for the top speed of the hand cycle under the sole power of the

motor to be 32 km/h, as this is the maximum allowable speed on city bike paths.

From the power equation, we know that the power required is the desired velocity of the hand

cycle multiplied by the restraining forces acting on the hand cycle.

Next we examine the resistive forces acting in the hand cycle. These include air resistance (Fa),

tire rolling resistance (Fr), and slope resistance (Fs).

The air resistance is related to the frontal area of the hand cycle and rider (A), the aerodynamic

shape factor (Cd), the density of air, and the velocity of the hand cycle squared as shown in the

formula below. The Cd value for the average commuter bicycle is listed as 0.8 in the bicyclingscience textbook. As the hand cycle has a lower and smaller profile as a commuter bicycle the

Cd value should be lower. However no data exists for hand cycles so a Cd of 0.8 was used.

Slope resistance is related to the normal force due to the mass of the rider and the hand cycle

and the slope of the incline. The formula is shown below.


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Rolling resistance is given by the normal force due to rider and hand cycle mass and the

coefficient of rolling resistance (Cr). Cr is listed as 0.001 for high pressure racing tires on wood

surfaces to 0.01 for wide low pressure commuting tires on gravel by the bicycling science

textbook. Since the hand cycle has three mountain bike tires, two of which are at a 15 camber,

the largest Cr is used.

Substituting the different resistive forces into the power equation the following equation is derived

( )

As hub motors are only available with certain power ratings, of 250W, 350W, 400W, and 500W

these values are input into the equation resulting in a cubic function from which velocity can be

solved. The power transfer efficiency from motor to the ground is assumed to be 90%.

( )After solving the above equations with different power and slope angles, it was determined that

the 250W motor would be sufficient to power the hand cycle. It provides a speed of 29.8 km/h on

flat ground and 6.0 km/h up a 12% incline. These values may be slightly higher in reality as the

values used for Cd and Cr coefficients may be higher than in real life as no data was available for

hand cycles. The complete results of the calculations and the Matlab program used to calculate

these results can be found in appendices A and B.

As a final check the calculated values were compared to available data for bicycles from the

bicycling sciences textbook. The values calculated showed very similar results to the available

data. This data is shown in chart form below. In the graph shown below a utility bicycle powered

with 250 W reaches approximately 9m/s or 30 km/h.

Figure 17 - Power Required to Propel Various Bicycles


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Apart from the power calculations, the dimensions of the hub motor needed to be verified in order

to determine the compatibility with the hand cycle fork. From the manufacturers CAD drawings

shown below we were able to conform compatibility.

Figure 18 - CAD Drawing of Hub Motor

6.3 Final DesignThe final design of motor used a 24V, 250W brushless hub motor from Goldenmotor.ca, which is

shown on the figure below. Based on testing, this motor was able to provide a constant speed of

26km/h on a flat road. It was also able to provide a significant assist when going uphill, which

achieves the design objective and complies with the design requirements.

Figure 19 - Integrated Hub Motor


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7.0 Lithium Battery

7.1 Battery DescriptionThe battery is the power source for the system. It has a significant impact on the performance

characteristics of the final product. The most notable specifications affected by the battery are

the run time for each use and the average time before major maintenance is needed. There aremany available and configurations and chemistries of batteries, each with distinct properties.

Even with the same nominal chemistry and power, the advertised operating conditions, expected

life span, and cost vary significantly between different manufacturers. Most Lithiumbatteries are

produced in China and can be purchased online from Chinese retailers at a reduced cost. During

the preliminary investigation, shipping was found to vary between $50 and $140 from different

manufacturers.

Manufacturers Specifications:

Nominal Capacity (AH) 10ah

Nominal Voltage (V) 24V

Source Resistance (m about 120

Cell Specification 3.7V 5AH

Cell Combination2-parallel

7-series

Cell Size16*58*70

mm

Lifecycle of the whole pack: >85%capacity

after 1000

cycles.

Cell Quantity (parallel*series) 14

Discharge Cutoff Voltage (V) 20.8

Charge Cutoff Voltage (V) 29.4

Rated Discharge Current (A) 10

Instantaneous Max. Discharge Current

(A)25

Maximum Continuous Discharge Current

(A)10

Maximum Continuous Charge Current

(A)5

Charge Mode CC/CV

Standard Charge Current (A) 2A

Charge Time under Standard Charge

Current6

Fast Charge Current (A) 5A

Charge Time under Fast Charge Current 2.5

Charge Temperature Range -20 - 60

Discharge Temperature Range -20 - 60

Battery Gross Weight 4.5kgs

7.2 Battery DesignOther than the chemistry, the major parameters which must be specified when purchasing a

battery are the nominal electric potential (V) and volume of charge stored (Ah). In order to make

an appropriate selection, the total energy capacity and resulting run times when paired with

various common motor powers are calculated and shown below. All batteries are subject to


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degradation over time and charge cycles. The calculations are based on the manufacturer's

nominal values and should adequately represent the actual system in the as-new condition. The

Lithium assemblies considered for this project are specified by the manufacturers to have greater

than 85% of their initial capacity after 1000 charge cycles.

The standard form of the electrical power equation is:

Where: P= Power in Watts

V=Electric Potential in Volts

I= Current in Amperes

Batteries are rated by Voltage and Ampere hours. For comparison with motor ratings this needs

to be converted to a standard form:

Where: E= Energy in Joules

The calculations presented here will assume that electrical losses and the power consumption of

auxiliary components are negligible when compared to the power consumed by the motor.

Table 3 - Resulting Energy Storage for Several Common Battery Configurations

The power consumption of motors is measured in Watts.

Where: Pm= Nominal Motor Power (W)

t = Run time at full power (min)

When the previously considered batteries are paired with the available hub motors, the following

run times are anticipated.

24 36 48

5 432 648 8648 691 1037 1382

10 864 1296 1728

12 1037 1555 2074

15 1296 1944 2592

Potential (V)

Charge(Ah)

Energy Storage (kJ)


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Table 4 - Expected Full Discharge Run Times Under Full Power

While cost varies significantly with manufacturer and source, a representative value (the price

given in a formula by Liberty Electric Bikes, www.iloveebikes.com, can be used as a first

approximation.

Table 5 - Expected Cost of Various Battery Sizes

7.3 Final DesignThe final design uses a frog style Lithium 24V, 10Ah battery pack from Goldenmotor.ca, which is

shown in figure 20. The battery is attached behind the seat of the handcycle and connected to the

controller.

From the table above, this battery is rated to give 58 minutes of run time at full power. In the

battery testing, it lasted about 48 minutes at full power on a flat road. Considering the disturbance

factors, the results are satisfactory.

24 36 48 24 36 48 24 36 48

5 29 43 58 21 31 41 14 22 298 46 69 92 33 49 66 23 35 46

10 58 86 115 41 62 82 29 43 58

12 69 104 138 49 74 99 35 52 69

15 86 130 173 62 93 123 43 65 86

Charge(Ah)

Potential (V)

Nominal Motor Power (W)

Potential (V)

250 350 500

Aproximate Run Time

at Full Power (min)

Potential (V)

24 36 48

5 $140 $210 $280

8 $224 $336 $448

10 $280 $420 $560

12 $336 $504 $672

15 $420 $630 $840

Charge (Ah)

Representitive CostPotential (V)


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Figure 20 - Final Battery Selection

8.0 Fabrication and Integration

Only one component needed to be manufactured for the project. This was the brakemounting bracket or tab used to mount the calliper of the disk break onto the fork of the

handcycle. This process consisted of three main steps.

The first step to fabrication was to build a mock up of the tab to check clearances and fit

between the rotor, fork, and calliper. This was done by measuring out the tab

dimensions onto a piece of cardboard. This was then cut out using a utility knife. Some

clearance issues were discovered and the CAD model was adjusted accordingly.

Drawings were drafted for the machine shop to produce the part. This drawing is shown

below.

Figure 21 - Drawings for Manufacture for Disk Brake Tab


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The tab was cut from mild steel plate using a water jet. The Water jet was selected as

it was the most economical way to cut the part. The tab has only 2 dimensional features.

The third dimension of thickness can be determined by the thickness of plate being cut.

The complete time to program and machine two tabs was 15 minutes. Two tabs were

manufactured in the unlikely event the tab will be damaged during operation. The edges

of the tab were then ground down slightly to remove any sharp edges. The tab after

being cut by water jet is shown below.

Figure 22 - Disk Tab after Water Jet Cutting

The final step of the tab manufacture was to attach it to the handcycle. This was done

using the TIG (Tungsten Inert Gas) welding method. TIG welding was selected do to the

ability of the operator to adjust the welding heat setting on the fly via a foot peddle. This

was important as the tab is much thicker than the tubing walls on the fork. This could

lead to the problem of burning through the thinner fork material if the heat was not

properly regulated.

Another step taken to prevent burning through the fork tubing wall was to preheat the

thicker tab to 200F using a propane torch prior to welding. As filler metal ER702-S rodwas selected. This rod was selected as it is compatible with both the mild steel of the tab

and the chromoly steel of the fork. The tab welded to the fork is shown in the figure

below.

Figure 23 - Tab Welded to Fork


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8.1 Integration and AssemblyThere were two parts to the integration of the power assist system onto the handcycle. The first

was integrating the hub motor into the front wheel of the hand cycle, and the next was the

installation of the other necessary components onto the hand cycle. For all of these parts it was

important to ensure rider usability and safety.

In order to integrate the hub motor into the front wheel the original front wheel needed to be

completely disassembled. This was done by unthreading the spokes one by one and removing

them from the rim and hub. Below the disassembled wheel is shown.

Figure 24 - Disassembled Wheel

The hub motor was then mounted into the wheel in place of the original hub and the wheel was

rebuilt following the same steps used to disassemble the wheel but in reverse. Since the hub

motor has a larger diameter than the original hub shorter spokes needed to be used. The lengthof spoke required for the hub motor was not commercially available so each of the original spokes

was cut to size and rethreaded. When rebuilding the wheel it was ensured that proper lacing

patterns were used for the spokes to ensure maximum wheel strength. The standard lacing

pattern for a wheel is shown in the figure below.


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Figure 25 - Spoke Lacing Pattern

The next step of the integration process was to install the remaining components of the power

assist system. During installation it was ensured that components were installed to provide ease

of use for the rider and to ensure rider safety. The components installed and considerations made

during installation are discussed below.

Battery and Master On/Off Switch:

The battery and master on/off switch were mounted on the rear of the hand cycle. During

installation of the battery it was ensured that the charging jack on the battery was oriented and

located in such a way that it can be easily reached to charge the battery. For the master on/off

switch it was ensured that it was oriented upwards and also easily accessible.

Brake Lever with Control Switch:

The brake lever was installed with a slight orientation downwards. This configuration was found to

be the most ergonomic during testing. After installation the throw (distance from lever tohandlebar) was adjusted so that the rider can easily wrap their fingers around the lever while the

palm of the hand is firmly seated on grip.

Throttle and Cruise Control Switches:

On a traditional E-bike the throttle and cruise switches are on opposite sides of the handlebars.

As the rider must take his hands off the steering mechanism to reach the bars it was decided to

install the throttle and cruise control switches on the same side so the rider can still steer while

adjusting the power settings. Several different configurations were tried to find the most

ergonomic layout for the user.

Control Box:

The Control box was installed so that it is out of the way and does not interfere with the riders

operation of the handcycle. To protect against moisture and grit encountered while riding, the

control box is encased in a weatherproof box.


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8.3 SafetyTo ensure the safety of all individuals involved in the fabrication and assembly of the project it

was ensured that proper personal protective equipment was used when required, furthermore

machinery and tools where only operated by those with proper training. While operating the water

jet safety glasses where worn. Pinch points were indentified before undertaking assembly of any

components onto the handcycle.

9.0 Verification and Test PlanThe following section outlines a detailed procedure of the tests performed and all of the results. It

is broken down into functionality tests, which were done to verify that each part was properly

connected and integrated and therefore worked, and performance tests, which were done to

verify that the overall system met the design specifications. There is also a section entitled

Verifications which were to verify certain aspects of the system such as weight and functionality

with the other group working on the handcycle.

9.1 Verifications

9.1.1 Weight:

The handcycle was weighed before the components of our system were installed and after to

verify the weight of our system. As stated in the project specifications, the entire system mustnt

add more than 30 lbs to the handcycle weight. The overall weight of our system was determined

to be approximately 22 lbs. Most of the added weight was due to the weight of the battery, and

was mounted at the back. This was as per the request of the client to have the bulk of the weight

at the rear of the cycle.

9.1.2 Functionality with Other Group:

Once our group and the wheelchair towing device group were finished the assembly of the

system, they were both installed on the handcycle at the same time to verify that they didntinterfere with each other. Figure x below shows the rear of the cycle, where the towing device is

mounted. As can be seen from figure x, no interference was observed.


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Figure 26 - The Rear of the Cycle with Both Systems Installed

9.1.3 Functionality Tests

Upon integrating our entire system with the hand cycle, the first step was to verify if all of the

features worked properly.

Table 6 - Functionality Tests Performed

Part to be tested Test Description Results

Battery / Ignition Turn the ignition to on and verify

if the lights on the battery indicator

turn on.

Passed Turning the ignition

switch to on did indeed turn on

the battery

Throttle / Motor Increase and decrease the throttle

setting and verify that the motor

power changes with the throttlesetting

PassedThe motors output

responds to twisting the throttle

Cruise Control Switch Set the throttle to any desired

power output and press the cruise

control button. Release the

throttle and verify the motor output

remains constant

Passed The cruise control

button does hold the motor output

power constant at the level it was

at when the button was pressed.

The battery and control box

(nearest components of oursystem)

The wheelchair towing device


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Disc Brake Spin the front tire and engage the

brake. Verify that the calliper

closes on the rotor and stops the

front tire.

Passed Squeezing the brake

handle engages the brake

Power Kill Switch Set the motor output to full power

using the throttle and set cruisecontrol. Lightly squeeze the brake

lever and verify that the power to

the motor is shut off.

Passed When the brake lever is

squeezed, the motor disengages.

9.2 Performance TestsThese are the more detailed tests to verify the performance of each of the components against

the specifications.

9.2.1 The Speed Test

This test was designed to verify the maximum speed that can be attained on a flat surface from

the power of the motor alone. Five trials were performed to confirm the consistency of the results

The test procedure:

- Two markers were setup spaced 100m apart (distance was measured using GPS)- Rider powered up to full speed before passing the first marker- Stopwatch timer was started when rider passed first marker- Rider continued in a straight line past second marker- Stopwatch timer was stopped when rider passed second marker- Time taken to travel 100m used to calculate average speed- Calculated speed was compared to speed measured by on-board speedometer-

Pass / Fail requirements:

- The handcycle must not travel faster than 32 km/h when powered solely by themotor.

(1)

- The handcycle must travel at least 15 km/h when powered solely by the motor.

Results:

As can be observed from the results in table 7, the average top speed of the handcycle travellingon a flat surface is ~26 km/h, which passes both of our requirements. The calculated speedswere very close (within 5%) of the ones measured by the speedometer.

Table 7 - Results for the Speed Test

Trial # Time Taken (s) Speed (km/h)

1 13.3 27.07

2 13.1 27.48

3 14.2 25.35

4 13.9 25.90

5 14 25.71

Calculated average speed over 100m


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9.2.2 The Brake Distance Test

For safety reasons, the handcycle must be able to stop within a short distance to avoid collisions.Minimum braking distances required to avoid tipping were calculated using several assumptions(see section on brake components) and these numbers were used as a basis for deciding the

pass/fail requirement. The braking distance was tested on both a flat surface and on a 20incline.

The test procedure:

- A marker was setup- Rider would travel up to full motor speed (determined to be 26 km/h from speed test)

o For the hill test, a speedometer was used to measure a speed of 40 km/h- Brake was engaged as the rider passed the marker- Once bike stopped, the distance from the marker to the front tire was measured- During test, the cycle was observed carefully to check for any tipping

Pass / Fail requirements:

- The handcycle must stop in less than 6m on a flat surface without tipping.- The handcycle must stop in less than 10m on an inclined surface without tipping.

The results:

As can be seen from tables 8 and 9, the stopping distances from travelling 26 km/h on a flatsurface were in the range of 2.5-3m and the stopping distances from travelling 40 km/h on a 30incline were in the range of 5.5 6m. No tipping was observed during the tests.

Table 8 - Results of the Flat Surface Brake Test Table 9 - Results of the Incline Brake Test

9.2.3 The Battery Endurance Test

This test was to confirm battery capability at full power. Theoretically, the battery should last 58minutes at full power.

The test procedure:

- The battery duration was tested at three different power settingso Full Throttleo Half Throttleo Power Assist at Half Throttle

- The handcycle was ridden for a full battery charge at each of the three throttlesettings

- The test was performed in a residential cul-de-sac with very little traffic to avoidstopping

Braking Distance from 26km/h on flat ground

Trial # Braking Distance Any Tipping?1 2.4m No

2 2.7m No

3 2.8m No

4 2.9m No

5 2.9m No

Braking Distance from 26km/h on incline

Trial # Braking Distance Any Tipping?1 5.6m No

2 5.6m No

3 5.7m No

4 5.8m No

5 5.7m No


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- The battery duration was recorded- The battery was fully re-charged after each test

Pass / Fail requirement:

- The battery must last at least 45 minutes at full throttle

The results:

As can be seen from Table 10, the battery passed the requirement

Table 10 - Throttle Setting vs. Run Time

Throttle Setting Battery Run Time

Full Throttle 49 minutes and 57 seconds

Half Throttle 86 minutes and 43 seconds

Power Assist at Half Throttle 90 minutes and 27 seconds

9.2.4 The Overall Performance Test

This test was to verify that all of the components worked throughout an entire ride and there wereno bugs in the system.

Test Procedure:

- The handcycle was ridden around for 30 minutes- During the ride, the motor was used with and without cruise control, going up hills

and on flat surfaces, and at many different throttle settings, including power assist- The rider made several stops and turns while the motor was running- The rider was required to note any bugs or issues that arose during the ride

Pass / Fail requirement:

- All of the components should work throughout the entire ride without any defects

Results:

No issues were observed during the ride.

10.0 Risk AnalysisTable 11 - Risk analysis table (10 indicates high risk or probability and 1 indicates low risk or probability)

Unit Failure Mode Affect on

system

Probability of

occurrence (1-

10)

Associated

level of risk (1-

10)

Remedial

Action

Throttle

Switch

Open Circuit No power when

needed

2 1 Use robust

switch

Closed Circuit Continuous

current to motor.

2 7 Install kill


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Drain on battery.

Uncontrolled

speed increase

switch

Stuck on Continuous

current to motor.

Drain on battery.Uncontrolled

speed increase

3 7 Install kill

switch. Use

robust switch

Battery Short Circuiting Drain on battery

power.

Overheating of

battery

1 8 Install fuse on

battery leads

Controller Stuck on full

power

Uncontrolled

speed increase.

1 8 Install kill

switch to

override

control signal

No signal to

motor

No power to

system. Hand

cycle will not

move

2 1 Use quality

controller

Electrical

wires

Wearing

through of

insulation

Short circuiting

of components.

Wires become

hot may cause

burns

4 7 Use quality

wire.

Install fuse at

battery to kill

power through

cable. Route

cables where

they will least

likely be

damaged.

Overheating Increased

resistance loss

of power

2 7 Use large

gauge wire.

Brake Cable breaks Loss of all

braking ability

1 8 Use high

quality cable.

Instruct user

to inspect

regularly.

Mounting point

on fork break

Loss of all

braking ability

1 8

Contaminant on

brake pads

Decrease in

braking power

6 4 Inform user to

inspect and

keep brakes

clean


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11.0 Project Management PlanProject Management is a proactive approach that requires constant assessment and adjustments

to maintain schedule. Throughout this semester, tracking of our schedule was important to

ensure on time completion. The following graphs and tables outline our Responsibility Matrix,

Work Break Down Structure, Scheduling and Budget. We have met our completion date of April

8, 2010, using all our contingency time due to an unanticipated weather occurrence thatprolonged our testing. It was important to consider contingency time for unanticipated

occurrences. In our case, an unforeseen snowstorm had delayed our final battery testing by a

week. Having our ten days of contingency allowed us to adjust our plans and meet our required

deadline without consequence. It was important for us to constantly keep track of schedule to

ensure tasks were being met on time.

11.1 Team OrganizationThe success of our project is attributed to the teamwork put forth by all the group members.

Although tasks were divided individually, helping one another was essential to our success. All

tasks were overlooked in a group perspective with support being provided as necessary. The

following is a responsibility matrix outlining task work lead by the primary lead, with an appointed

secondary support.


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Responsibility Matrix

P-PRIMARY S-SECONDARY

Task Name Resource Resource Resource Resource Resource Resource

Mahmoud Stephen Greg Darcy Kenny Manuel

Cost Analysis S P

Finalizing Best

Price on Brakes

P S

Finding vendor

Motor/Controller

and Battery

P P P P P P

Purchasing

Completed

Components

P

Motor,

Controller and

Battery

Assembly

Re-Spoking

Wheel/Attaching

Motor Hub

P

Drilling Hole in

Control Box

S P

Re-evaluation of

system layout

P

Painting P

Final Assemblies S S S P S S

Brake

Construction

Removal of

Current U Brake

P

Disk TabP


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Fabrication

Welding Disk tab

to fork

P

Final Assemblies

(Rotor + pads)

S S S S S P

Testing

Maximum Speed

Test

P

Braking Distance P

Battery

Endurance Test

P

Overall

Performance and

Reliability

P P P P P P


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11.2 Work Breakdown Structure

Figure 27 - Work Breakdown Structure

Electric MotorPower Assist

For HandCycleFinal Product

Final DesignWork

CostAnalysis

Finalizing BestPrice on Brakes

Finalizing BestPrice on Hub

Motor

Finalizing BestPrice on Li-ion

Battery

Miscellanous

ForkTolerances

Creating BrakeCaliper in

Solidworks

Purchasing

CompletedComponents

Hubmotor +Controller+ Li-

ion Battery

MechanicalDisk Brake

Rotor

Construction

Assembly

Disk Brake

MachiningCaliper Design

WeldingCaliper

AttatchingRotor and

Brakingcontrols

Motor.Controller &

Battery

Re-spoking tireand attatching

Hub Motor

AttatchingBattery andController

Testing

Overall Tests

TotalFunctionality

CustomerApproval

Brake

StoppingDistance

Test

HubMotor/Contr

oller

TopSpeedTest

Ba

EnduTe


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11.3 Schedule and Gantt Chart

Figure 28 - Schedule

ID Task Name Duration Start Finis h Predecess ors Resou

1 Completion of Final Product 65 days Mon 1/10/11 Fri 4/8/112 Final Design Work 55 days Mon 1/10/11 Fri 3/25/113 Cost Analysis 20 days Mon 1/10/11 Fri 2/4/114 Finalizing Best Price on Brakes 10 days Mon 1/10/11 Fri 1/21/115 Finalizing Best Price on Motor/Controller 10 days Mon 1/10/11 Fri 1/21/116 Finalizing Best Price on Battery 10 days Mon 1/24/11 Fri 2/4/11 57 Purchasing Completed Components 10 days Mon 2/7/11 Fri 2/18/118 Wait time 10 days Mon 2/7/11 Fri 2/18/11 4,5,69 Construction 52 days Mon 1/10/11 Tue 3/22/1110 Motor, Controller and Battery Assembly 22 days Mon 2/21/11 Tue 3/22/11 811 Re-Spoking Wheel/Attatching Motor Hub 9 days Mon 2/21/11 Thu 3/3/1112 Drilling Hole in Control Box 2 days Mon 2/21/11 Tue 2/22/1113 Re-evaluation of system layout 8 days Fri 3/4/11 Tue 3/15/11 11,1214 Painting 3 days Wed 3/16/11 Fri 3/18/11 1315 Final Assemblies 2 days Mon 3/21/11 Tue 3/22/11 14,13,12,116 Brake Construction 14 days Mon 1/10/11 Thu 1/27/1117 Removal of Current U Brake 3 days Mon 1/10/11 Wed 1/12/1118 Disk Tab Fabrication 6 days Mon 1/10/11 Mon 1/17/1119 Welding Disk tab to fork 3 days Tue 1/18/11 Thu 1/20/11 17,1820

Final Assemblies (Rotar+pads) 5 days Fri 1/21/11 Thu 1/27/11 19,18,1721 Testing 3 days Wed 3/23/11 Fri 3/25/11 922 Maximum Speed Test 3 days Wed 3/23/11 Fri 3/25/1123 Braking Distance 3 days Wed 3/23/11 Fri 3/25/1124 Battery Endurance Test 1 day Wed 3/23/11 Wed 3/23/1125 Overall Performance and Reliablilty 3 days Wed 3/23/11 Fri 3/25/1126 Customer Approval 1 day Wed 3/23/11 Wed 3/23/1127 Contingency Time 10 days Mon 3/28/11 Fri 4/8/11 2


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Figure 29 - Gantt Chart

11.4 BudgetThe following is a comparison of our Estimated Budget vs. Actual Cost. What we had budgeted

for the fabrication and assembly of the brake tab was much higher than what we had actually

spent. Contingency costs were also higher than what we actually had to use (about 40 % of what

we anticipated).


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Table 12 - Estimated Bill of Materials

Table 13 - Actual Bill of Materials

Parts* Quantity Price($)

24V250W DC Motor (Rear) 1 84

24V Thumb Throttle 1 10

24V10Ah Lithium battery 1 198

Cruise Controller 1 65

Cruise Controller Box 1 10

Brake Lever 1 12

Wires N/A 10

Shipping & Handling N/A 110

Disk Brake** 1 11

Tab 1 6

Assembly Consumables and spare

parts N/A 10

Total 526


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12.0 Conclusions and Recommendations for Future WorkThe design and integration of a power assist system onto the clients existing hand cycle was

successful. Our design specifications were met or exceeded with the design that was

implemented. Several challenges were encountered during integration of the system due mainly

to that the hub motor was of irregular size. Upon completion of the first test ride the client

expressed his satisfaction with the final prototype.

12.1 Suggested Project Extensions, Additional Analysis, Value Added

Project Design ActivitiesSeveral things could be improved to improve the riders experience. Work could be undertaken to

improve current stability problems with the hand cycle as these present a risk for injury to the

user. Another area of improvement on the hand cycle would be to improve the system for

powering the hand cycle with the hands. A linear system using an action similar to rowing could

be investigated to improve rider efficiency and comfort.

13.0 References[1] Government of Alberta.(Updated 2009). Operators License Information for Motorcycles,

Mopeds and Power bicycles. [Online Handbook]. Available:

http://www.transportation.alberta.ca/content/docType45/Production/Motorcyclehandbook2010.pdf

[2] D.G. Wilson, Bicycling Science, 3rd

Edition, Massachusetts: MIT, 2004, 237-263

[3] Hayes Mountain Bike Disc Brake Operating Specs. Hayes (current December 6, 2010)

[4] Brake Lining Wikipedia (current December 6,

2010)


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Appendix AMatlab Code to calculate hand cycle velocity from power.% power.m% Bike velocity from power Calculator% Manuel Hopf% Nov 28 2010

% Inputsclear allg=9.81; %acceleration due to gravity (m/s^2)mb=16; % mass of handcycle (kg)mr=74.8; % mass of the rider (kg)mm=5; % mass of motor (kg)mbat=10; % mass of battery (kg)

mtot=mb+mr+mm+mbat % Total weight

Af=0.5; % frontal areas (m^2)Cd=0.8; % Aerodynamic shape factor

Ro=1.225; % Air density (kg/m^3)

Cr=0.01; % Coefficient of rolling resistance (from 0.001 to 0.01)

slope=0; % gradient of slope in%theta= atan(slope/100); %Angle of slope in degrees

P=250; %motor power in wattsef= 0.9; %power transfer efficiency

%Air resistance componentFa=0.5*Ro*Af*Cd

%Slope resistanceFs=mtot*g*sin(theta)

%Rolling resistanceFr=mtot*g*Cr

%P=(Fa*v^2 + Fs +Fr)*v

% Power needed is the force to overcome times velocity% Solving the cubic equation

syms vvel=Fa*v^3 +(Fs+Fr)*v -(P*ef)

x= solve(vel)

velocity= (x)*3.6 % converts from m/s to km/h


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Appendix B1: Braking Program

Matlab code for calculating braking acceleration%Program to figure out acceleration%Written: Greg Fry%For Class ENME 538%this program gives the acceleration due to the brakes in the opposite%direction of the rider's motion%3rd revision

%The following assumptions are made:%Wheels continue to roll while braking (ie: tire friction is

negligeable)%The effect of drag while braking is negligeable%The stopping distance will be 5mclearclcspeed = [25:1:60]; %Speed declared in km/h, from 25 to 60v = speed/3.6; %convert speed to m/s^2

[p,n] = size(v);slope = [0:0.005:.12]; %slope is rise over run, ie opp/adj (tan)theta = atan(slope);g = 9.81;[r,m] = size(theta);sd = v(:).^2/(20*(0.85+0.014));for i = 1:n

if i


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Appendix B2: Braking acceleration results

ENME Final Report -HAndcycle Motor

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