ROBOTIC TIGER P

Agenda  Project Recap/Proposed Design  Updated Engineering Specs  Customer Needs  System Connections & Interactions  McKibben Air Muscle Testing  Air Supply Selection  Power Supply Selection  Logic Selection & Implementation  CAD Model  Model Analysis  Bill of Materials  Risk Assessment  Test Plan  MSDII Schedule

Project Recap/Mission Statement  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

Customer Needs Customer Need Importance (1 = high)Description CN11 Can jump forward a distance equal to at least the length of its body (only 1 jump required per tank fill) CN21Use air muscles to provide jumping force CN31Lands safely without damage CN42 Is ready to jump again after landing, without user adjustment of robot body or legs CN52Self-contained (on board power sources) CN62Portable (small enough for one person to carry) CN72 Reasonable battery life; battery charging takes hours CN83Resemble a tiger CN93Controls do not yield a noticeable delay

Proposed Design:  Completely self contained robotic tiger  On board air supply, power supply, controls, & muscles  Utilizes McKibben Air Muscles to create jumping motion  Patterned attachment holes in legs to allow for air muscle testing and adjustability  Air release controlled using an Arduino Board and sprinkler valves  Rechargeable power & refillable PVC pressure chamber

Specifications SpecSourceMetric Unit of MeasureMarginal ValueIdeal Value Preferred Direction S1CN1Horizontal Jump DistanceFeet1*body length1.5*body lengthUp S2CN1,2Uses Air Muscles Binary Yes S3CN3Sliding Distance After LandingInches 3 2Down S4CN4,5Self-Contained Binary Yes S5CN3,6Overall WeightLbs5025 Down S6CN3,5,6Overall LengthFeet42Down S7CN3,5,6Overall HeightFeet21Down S8CN3,5,6Overall WidthFeet1 Down S9CN8Resemble a Tiger Percent80 100Up S10CN2Regulated Air Pressurepsi60<60Down S12CN9Total Response Time to Jump Commands Down S13CN2,9Solenoid Response Timems5025Down S14CN2,9Muscle Fill Times.5.25Down S15CN2,7Battery Life# of Jumps1100Up S16CN2,8Two Actuated LegsBinary Yes S17CN4,5Tank can be filled in less than 5 minutesBinary Yes

System Connections Battery/Tether Power Runs Compressor Air Energy from compressor is stored in tanks Pressure energy is converted into motion Air Muscles and Cables Moves hind legs for jumping action Leg Mechanism function simultaneously for Jumping motion Arduino Control Board Sends a Output through relay board Output Changes the state of the Solenoid Valves Tiger Jumps Forward

Air Muscles  Rubber tube inside of a braided mesh sleeve  Pressurized tube inflates causing the mesh to contract in length  Closely mimics biological muscles

Pressure Chamber Design  Topics of concern  Flow Rate Currently the muscles fill to slowly to lift the robot from off the ground.  Force during contraction Currently we are able to achieve a maximum force of about 30lb per air muscle. However the force during the contraction is much lower resulting in slow weak movements.  Bottlenecking This occurs at all the current joints where air is flowing and is impacted by the smallest inner diameter of the first connection currently this is the solenoid. (shown on the left) Even with larger port sizes (3/8” shown) for fittings the valve inlet and outlet is small (yellow) and restricts flow.

Proposed solution  Design to overcome obstacles  Use high flow rate valves The current solenoid valves shown on the previous slide do not have good flow rate as demonstrated in the YouTube videos. The solution to this issue is the use of sprinkler valves, they are rated for the pressure required and the offer very high flow rate. This high flow rate will help achieve a faster muscle fill and cause the robot to jump. These will also have to be modified from there original design to allow fast operation.

Proposed Solution  Design to overcome obstacles  Use larger fittings The current muscle fittings have a small port ID and will need to be increased to allow the muscle to fill at a faster rate.

Proposed solution  Design to overcome obstacles  Change the pressure chamber  Safety??? The current use of a 3000 psi pressure chamber with 60 psi regulator while good for previous air muscle projects limits the flow rate of the air leaving the chamber. The proposed solution utilizes a lower Psi chamber that will allow a greater flow rate leaving the nozzle. Pressure chamber Valve location Fill location This Pressure chamber was designed with the use of a very rough calculation to check the final muscle pressure in the muscles was optimal while the pressure in the tank was set to 60Psi.

Alternative Solution  Design to overcome obstacles  Change the pressure chamber These aluminum air tanks are lighter but are expensive.

Basic Volume Calculations

Controls Selection  What we are planning to use:  Arduino Mega 2560 Simple programming language 54 channel capability Fully autonomous Cost effective (existing part)

Power Supply  9V battery to power Arduino board  3 9V batteries in series to power sprinkler valve solenoids  Cheap and lightweight  Solenoids  Draw 400mA for 1 sec to hold valve open, each  At 20 jumps per hour, battery lasts 180 hrs

Solenoid Control Board  Provides signal from the microcontroller to the solenoid valve for muscle actuation. There will be one iteration of this circuit per solenoid used to control muscle contraction order.

Jump Logic Power On Wait for Go Input Command Return Go? No Contract muscle Group 1 Yes Contract muscle Group 2 Contract muscle Group 3 Wait Release muscles

Continued air muscle testing was preformed (different way of mounting air muscles tested; hooks on the fitting vs mesh loop used) Pre-compressing the mesh and stretching the muscles to get a bit more deflection Wooden leg built for project feasibility testing Attaching multiple muscles to a leg to get more force w Testing

Wooden leg Prototype Problems Encountered and things we Learned: Need for Tension on muscles for movement to occur Need for weight on upper body link Lack of a stop for the upper body link Unable to launch with stability with only one leg Leg needs to be angled in order to jump desired way No way to return to home position yet Could be improved with faster firing muscles (large orifice size)

Overall Design of Robotic Tiger

General Dimensions

Mass Properties  Weight Analysis  Assembly with PVC system 2-tanks ~ 18 lb  PVC system 2-tanks ~ 5 lb  Hind Leg Assembly ~ 1 lb x2  Front Leg Assembly ~.8 lb x2  80/20 Body ~ 10 lb This picture shows the center of mass as calculated by SolidWorks 2012.

Body Design  Body Design Merits  Strong  Adjustable Easily test multiple configurations  Light Weight  No Machining

Leg Design  General Design Merits  Adjustable Muscle anchor points Hard stops Pivot points  Simple Easily Manufactured Cheap  Versatile Ability to test and idealize multiple configurations  Light Weight

Leg Design Cont.  Pivot Points  Rod and Shaft Collar Design Cheap Proof of concept – prototype  Main Body – Leg Connector  Fork Style Holster Simple Proof of concept – prototype  Rod and Shaft Collar

Leg Design Cont. Leg Dimensions General Location ID #Length (in.)Width (in.)Thickness (in.) Plates in Parallel (y/n) Hind Legs n y n Front Legs n y n

This picture is meant to be a visualization of our current idea for muscle ( ) and spring ( ) placement. Hind Leg Design  Function  Extension Needs to extend with enough force to lift robot off ground Air muscles in lever configuration  Retraction Springs Need to bring legs back but not interfere with extension to extensively

Front Leg Design  Uses identical hole pattern as back legs  Allows for adjustability  Hard stops  Spring attachment  Lengths  Initial position

Jump Dynamics  Simulation of take off  Reinforced the need for hard stops on legs  Inputs  Joint moments  Lengths  Masses/CM locations  Initial Angles  Outputs  IC’s for free flight

Jump Dynamics  Future – implement series of event detections  Fix each link when it reaches 45°  Remove the ground constraints at each foot when the normal force is zero

Free Flight Dynamics  Simulation models free flight of tiger  IC’s needed  Angles and rate of change  Position of foot  Uses  Test different setups  Find spring force needed for return

Free Flight Dynamics  Inputs  Spring coefficient  Damping coefficients  Centers of mass  Masses  Lengths  Outputs  Distance traveled  Animation/ positioning  Time for joint return

Free Flight Animation  Future work  Adjust system parameters  Event detection  Receive IC’s from jump program

Bill of Materials Air Supply/Connections Material/ItemOfficial NameQTY Unit Cost Total CostSourceDescription/Part Number Sprinkler Valves 2$19.00$338Global IndustrialRainbird ¾” valve Manifolds $ - On Hand Mesh $10.00 On Hand/TBD Muscle Tube 10ft$7.11$71.10Mcmastercarr 5236K531 conservative estimate Air Hose $ - On Hand/TBD Used to connect muscles to manifold Air Fittings $ -$40.00On Hand/TBD Tank to manifold connections PVC $ - On Hand Already purchased for proof of concept Body Construction Frame80/20 $ - Dr. Gomes14 feet Single, 2-Hole Brackets mcmaster carr47065T223 Fasteners for Brackets mcmaster carr47065T139 End-Feed Fasteners mcmaster carr47065T142 Panel Holders mcmaster carr47065T195 Plates mcmaster carr47065T141 Fasteners for Plates mcmaster carr47065T142 LegAluminum Sheet 1/4"2$16.02$32.04Mcmastercarr8975K24 6'x1' LegAluminum Sheet 1/8"2$9.97$19.94Mcmastercarr8975K17 6'x1" Lexan 1$28.08 Mcmastercarr8560K355 1'x2' Shaft Collars 20$0.84$16.80Mcmastercarr 9414T6 Power and Controls Batteries24V 2000 mAhr NiMH Battery1 $ - On Hand Existing battery pack from previous projects ChargerTenergy Smart Charger V1 $ - On Hand Existing charger from previous projects ArduinoArduino Mega $ - On HandMouser 782-A Wiring $ - On Hand Various elctronic connections and wires Relay Parts $ - On HandLegacy parts Total$255.96

Risk Assessment

Risk Assessment Continued

Further air muscle testing Looking for faster fill times Deflection and Force for bigger tube and mesh size Larger Impulse Testing with pressure vessel design Testing full build prototype Test Plan For MSDS II

Updated Schedule- MSDII MSD2Week 1Week 2Week 3Week 4Week 5Week 6Week 7Week 8Week 9Week 10 SuMTWRFS MTWRFS MTWRFS MTWRFS MTWRFS MTWRFS MTWRFS MTWRFS MTWRFS MTWRFS Test power supply Construct relay board Construct pressure chamber Test chamber fill and discharge Test muscles with chamber Mill legs/body Assemble legs Assemble final air muscles Program Arduino System assembly Test Trouble- shoot Poster Technical Paper

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