ROBOTIC TIGERP13029

http://www.plasticpals.com/?p=30286

Agenda• Project Goals• Legacy Projects• Air Muscle Info• Customer Needs• Specs• Functional Decomposition• System Flow Chart• Tiger Jump Dynamics• Jump Logic• Morphological Chart• Concept Selection (Pugh)• Tentative Parts List• Kinetics• Testing• Theoretical Muscle Force Calculations• 3D Modeling• Feasibility• Risk Assessment• Schedule

Project Goals

The project goal is to create a robot that mimics a jumping tiger both dynamically and to a lesser extent, aesthetically

The jumping force is to be provided by air muscles

Legacy Projects

P08023/08024 - Artificial Limb I/II P09023 - Artificial Limb III P10029 - Process Development for Air

Muscles P11029 - Biomimetic Crab P12029 – Biomimetic Robo Ant

Air Muscles

Rubber tube inside of a braided mesh sleeve

Pressurized tube inflates causing the mesh to contract in length

Closely mimics biological muscles

Air Muscle Contraction

• 28% contraction at 49psi under 29lb load

Air Muscle Fill Speed

• .18s to reach 28% contraction• Source: http://www.shadowrobot.com/downloads/datasheet_30mm_sam.pdf

Customer Needs

Customer Need

Importance (1 = high) Description

CN1 1

Can jump forward a distance equal to at least the length of its body (only 1 jump required per tank fill)

CN2 1Use air muscles to provide jumping force

CN3 1 Lands safely without damage

CN4 2

Is ready to jump again after landing, without user adjustment of robot body or legs

CN5 2Self-contained (on board power sources)

CN6 2Portable (small enough for one person to carry)

CN7 2Reasonable battery life; battery charging takes hours

CN8 3 Resemble a tiger

CN9 3Controls do not yield a noticeable delay

Specifications

Spec Source MetricUnit of

MeasureMarginal

ValueIdeal Value

Preferred Direction

S1 CN1 Horizontal Jump Distance Feet1*body length

1.5*body length Up

S2 CN1,2 Uses Air Muscles  Binary   Yes  

S3 CN3Sliding Distance After

Landing Inches  3  2 DownS4 CN4,5 Self-Contained  Binary   Yes  S5 CN3,6 Overall Weight Lbs 50 25  DownS6 CN3,5,6 Overall Length Feet 4 2 DownS7 CN3,5,6 Overall Height Feet 2 1 DownS8 CN3,5,6 Overall Width Feet 1   Down

S9 CN8 Resemble a Tiger  Percent 80  100 Up

S10 CN2 Regulated Air Pressure psi <60   Down

S12 CN9Total Response Time to Jump

Command s 0.3 0.15 DownS13 CN2,9 Solenoid Response Time ms 50 25 DownS14 CN2,9 Muscle Fill Time s 0.1 0.75 Down

S15 CN2,7 Battery Life# of

Jumps 50 100 UpS16 CN2,8 Four Actuated Legs Binary   Yes  

S17 CN4,5Tank can be removed in 5 min,

without tools Binary   Yes  

S18 CN1,2,3,4Allowable error in leg

measurement/adjustment Degrees 3 1 Down

Functional Decomposition

System Connections

Tiger Jumps

Forward

Tiger Locomotion

Using the average cat as a model, the muscular and skeletal systems were observed to get a basic idea of what muscles are involved in a feline jump with special attention given to the front and hind legs

Tiger Locomotion

Jumping force will come from the hind legs and lower back

Front legs will be used as shock absorbers for landing as well as getting the robot in position for each jump

1st

2nd

3rd

Bracing for Impact

Air Muscle Layout

Concept 1

Concept 3

Concept 2

Leg Design

Overhang for cable attachment

Jump Logic

Power On

Reset Muscle Positions to

normal

Wait for Go Input

Command

ReturnGo? No

Contract muscle

Group 1

Yes

Contract muscle Group 2

Wait for landing Sensor input

Hold

Release Muscles

No

Yes

Morphological Chart

Concept GenerationComponent Cheap Baseline Light Weight Sturdy Group Opinion

Air Supplysingle tank single tank carbon fiber tank multiple tanks single tank

Electrical sourceNiMH 2000 mAH NiMH 2000 mAH lithium ion lithium ion NiMH 2000 mAH

Controller push button w/ delay

push button w/ delay tethered control tethered control

push button w/ delay

Transportno handles no handles no handles handles no handle

Baseplate frame and plate frame frame and plate frame and plate

Base Materialplastics aluminum carbon fiber steel

plastics plate, aluminum tube

Leg Materialplastics aluminum composit tubing steel aluminum

Joint Materialplastics aluminum plastics steel plastics

Housing Covernone fiber glass none carbon fiber rapid prototyping

Pugh Chart

A B C D E

Cheap Baseline Light Weight Sturdy Group Opinion

Selection Criteria Weight Rating Weighted Score Rating Weighted

Score Rating Weighted Score Rating Weighted

Score Rating Weighted Score

cost +/- 3 1 3

DATUM

-1 -3 -1 -3 0 0

technical risk +/- 3 0 0 0 0 -1 -3 0 0

portability +/- 2 0 0 1 2 -1 -2 1 2

land safely without damage

+/- 1 -1 -1 1 1 1 1 1 1

air capacity +/- 2 0 0 1 2 2 4 2 4

reuses available parts yes/no 3 1 3 -1 -3 -1 -3 1 3

weight +/- 3 1 3 1 3 -1 -3 1 3

Total Score 8 0 2 -9 13Rank 2 4 3 5 1

Tentative Parts List

Legacy parts used to reduce cost Clippard Pneumatic parts

Material/Item Name QTY Description/Part NumberAir Tank Paintball HPA Tank 1 3000psi compressed air 48 cubic inchesRegulator Regulator for Paintball Tank 1 High pressure air regulatorSolenoids     24V solenoids Manifolds      Air Muscles      Air Hose     Used to connect muscles to manifoldAir Fittings     Tank to manifold connectionsBatteries 24V 2000 mAhr NiMH Battery 1 Existing battery pack from previous projectsCharger Tenergy Smart Charger 12-24 V 1 Existing charger from previous projectsArduino Arduino Mega 2560 1 Mouser 782-A000047Wiring     Various electronic connections and wires

Kinetics

MATLAB simulation will yield required forces from air muscles

Simulation consists of two portions Take off Free flight

A quick rough test rig was set up (see video bellow) In order to see how muscles behave under loading (deflections, Inflation speeds, max force to failure) and also get a rough idea of what kind of forces and deflections we can get out of an air muscle, Much more testing to come

Blue air muscle specs:Roughly .5” deflection32 lbs till Failure (fitting pulled out)

Preliminary Testing

Test Muscle Data

Tested Air Muscle Dimensions\Information

Tube and Mesh Constructed Tube Mesh

Muscle Identity Uncompressed Length

Compressed Length

Dia. at Rest Max Dia. OD ID Material

Type Thickness Rest Dia. Contracted Dia.

Orange Mesh 4.625 3.5 0.3 0.595 0.18 0.09 Silicone 0.036 0.3 0.73RWB Mesh 4.5 3.25 0.28 0.745 0.18 0.09 Silicone 0.036 0.28 1Red Mesh 4.5 3.5 0.257 0.59 0.18 0.09 Silicone 0.036 0.257 0.573Tan Mesh 4 2.5 0.75 2.215 0.5 0.25 Silicone 0.125 0.75 2.5

Blue Mesh 3.4 2.9 0.5 1 Rubber 0.5 1.3

Theoretical Calculations

Calculations

Muscle Identity Weave Angle (degrees)

Weave Angle (radians)

Pressure (psi)

Dia. at Rest ε F

Orange Mesh 20 0.34906585 60 0.3 0.243243 18.74689RWB Mesh 20 0.34906585 60 0.28 0.277778 12.05734Red Mesh 20 0.34906585 60 0.257 0.222222 16.0316Tan Mesh 20 0.34906585 60 0.75 0.375 7.883798

Blue Mesh 20 0.34906585 60 0.5 0.147059 93.38133

Theoretical Air Muscle Calcs

• Source: http://lucy.vub.ac.be/publications/Daerden_Lefeber_EJMEE.pdf

Theoretical Air Muscle Calcs

Theoretical Air Muscle Calcs

Theoretical Air Muscle Calcs

3D Modeling

Rendering 2: Legs and tiger design in a ready to jump position.

Rendering 3: Concept in a fully extended position, just after jump initiation.

3D Modeling

Rendering 1: Shows the right side view of the 3D modeled concept leg design.

Design Sensitivity

Diagram: Shows dimensions used in design sensitivity analysis of leg joints.

DR

F

Design Sensitivity

Design Sensitivity

Design Sensitivity

Feasibility

Battery Life (continuous use, 2000mAh 24V NiMH) L=battery life, I=current per solenoid

Force Simplified linear actuator model 165lbs of force for 20lb robot to jump 1.6ft

𝑡 = 𝐿𝑁(𝐼𝑠𝑜𝑙𝑒𝑛𝑜𝑖𝑑 )

𝑡 = 2000𝑚𝐴ℎሺ3ሻ(4)(27𝑚𝐴) 𝑡 = 6.2 ℎ𝑟𝑠

Risk AssessmentRisk Effect Cause Chanc

e of Occurring

Severity Importance

Action to Mitigate

Long Lead Time

Unable to complete robot construction due to lack of certain ordered parts.

Natural for some unique parts. Poor group planning

3 4 12

Make sure to plan on ordering specialized parts promptly. Include shipping times in planning.

Mismanaged Budget

Could result in changes in development.

Poor group planning and limited funds.

2 4 8Exercise budget management properly.

Mismanagement of Time

Unable to complete some aspects of project.

Poor group planning. Lack of time management.

2 3 6

Plan out all aspects of development and testing properly for allotted time.

Poor Documentation

Dissatisfied customer. Follow up projects would be hindered

Poor documentation throughout design and testing process.

2 4 8

Continually update logs and keep track of data. Make back-ups of data.

Group Dysfunction

Divergent design ideas.

Poor communication and decision protocol.

1 2 2

Build a decisions making system.

Inadequate Muscle Displacement

Lack of or sub-par jumping ability.

 

3 3 9

Research muscle capabilities before application.

Inadequate Muscle Force

Lack of or sub-par jumping ability.

 3 3 9

Research muscle capabilities before application.

Inadequate Air

Lack of or sub-par jumping ability.

 3 3 9

Test air supply options vigorously.

Malfunction of Air Muscle Cables

Binding or stretching of cables. Improper transmission of muscle force.

Improper cable material selection. Poor design/placement of cable paths.

2 2 4

Carefully design cable pathways and be aware of binding possibility during testing.

Air Muscle Contraction Timing

Uneven firing of leg muscles. Poor jump coordination

Improper circuitry. Poor design of calculations.

4 4 16

Properly test the programming of muscle firing.

Risk AssessmentRisk Effect Cause Chance of

OccurringSeverity Importance Action to Mitigate

On Board Power Supply

Failure of electronics to operate.

Not enough power supplied from on board. 3 3 12

Test power supply.

Dynamics Design Proper jump motion is not achieved.

Poor leg design5 4 20

Take care when in design phase.

Dimension Related Muscle Interference

Muscles cannot expand fully causing less than full utilization of muscle potential

Poor layout planning. Inadequate attention paid to design around muscles.

2 3 6

Take care when in design phase. Account for muscle expansion.

Air Muscle Performance Failure

Muscle tears or expands in an unexpected manner leading to poor dynamics and function

Poor construction protocol. Non-uniform construction quality of muscles.

4 4 16

Take great care when constructing each air muscle to ensure quality and uniformity.

Electrical Communication Failure

Failure of all solenoids to release air to muscles.

Extreme movement of this robot could loosen wires. Landing may also cause strong enough impulses to disconnect electrical circuits.

2 1 2

Make sure electrical connections are secure.

Material Failure Material yielding leading to failed operation.

Poor material selection/design.

3 2 6

Consider strains and stresses induced in structures when designing tiger.

Schedule

MSD1 Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F S Su M T W R F SMeet With Guide Learn Edge Code of Ethics Customer Needs Specs Benchmarking Functional Decomp System Flow Chart Risk Assesment Morph/Pough Chart Leg Concepts Tiger Leg Modeling Jump Logic System Design Prep System Design Review Muscle Data Collection Peer Review Create Test Plans Prototyping CAD Models Bill of Materials Arduino Code Project Manag. Review