Intelligent Robotics Laboratory Vanderbilt School of Engineering Artificial Muscle based on Flexinol motor wire Scott Renkes Advisor: David Noelle

Intelligent Robotics Laboratory Vanderbilt School of Engineering Goals  Design an actuator that mimics human muscle movements using Flexinol motor wire arranged in a bundle like structure  Control the actuator with an artificial neural network that utilizes the properties of the motor wire  Design the system to be easy to interface, modular and user-friendly

Intelligent Robotics Laboratory Vanderbilt School of Engineering Current Technology ActuatorProsCons Electric Motors Light weight Low power consumption Limited torque Stress on axel Hydraulics High force Heavy Pump required Pneumatics Medium force Elastic Non linear Pump required

Intelligent Robotics Laboratory Vanderbilt School of Engineering Why a new actuator?  Replicate human movement  Reduce stress on user  Better human interaction  Refined force and velocity control of device  Utilize the function approximation of controller  Human like movement allows for better man machine integration  Less training time  Humanoid robots can more easily mimic humans  Robot more acceptable

Intelligent Robotics Laboratory Vanderbilt School of Engineering Flexinol Density(g/cc) Energy conversion Efficiency (%) Max Deformation Ratio (%) Breaking Strength (MPa) Muscle Flexinol ,000  Shape memory alloy  Returns to memorized shape when stimulated  Heat stimulus  Only responds to stretching

Intelligent Robotics Laboratory Vanderbilt School of Engineering Fibrous Bundled Structure  Flexinol motor wire to replace muscle fibers  Package wires similar to muscle  Flexinol/muscle fiber proportional elasticity  Similar force/length curves

Intelligent Robotics Laboratory Vanderbilt School of Engineering Recruitment  One bundle, one neuron  Weak fast, slow strong  Properties of motor wire allow for variety of activation  Neural Network Controller  Force feedback training  Inverse Dynamics

Intelligent Robotics Laboratory Vanderbilt School of Engineering Feedback  Force feedback  Golgi tendon organ  Strain gauge  Length feedback  Muscle spindle  Approximation of Flexinol properties nawrot.psych.ndsu.nodak.edu/.../Movement/Reflex.html

Intelligent Robotics Laboratory Vanderbilt School of Engineering Flexinol Properties Diameter(mm) Linear Resistance  /m) Max current (A) Deformation Weight (g) Recovery Weight (g) Typical Rate (cyc/min)MaxPower(Watt)

Intelligent Robotics Laboratory Vanderbilt School of Engineering Neural Net Recruiting  Back Propagation Network  Neural Net Implementation  Computer  IC to Operation Voltage Amplifier  Force Controlled  Force feedback  Desired Force  Maximize F/t^2  Ensure recruitment

Intelligent Robotics Laboratory Vanderbilt School of Engineering Force Length Comparison  Muscle Force Length  See figure  Flexinol Force Length  Steeper slopes  Nature of Force Length Relationship  Tension  stretch

Intelligent Robotics Laboratory Vanderbilt School of Engineering EMG Controller  Muscle Voltage vs Muscle Force  EMG signals represent muscle force  Neural Network for EMG pattern recognition  Scaled EMG of biscep as input  Desired force as ouput  Relative to min and max The green line is bicep voltage The blue line is tricep voltage 3 and 4 are unused channels

Intelligent Robotics Laboratory Vanderbilt School of Engineering Circuit Diagram

Intelligent Robotics Laboratory Vanderbilt School of Engineering Artificial Muscle Implementation

Intelligent Robotics Laboratory Vanderbilt School of Engineering Sneak Preview Mk1

Intelligent Robotics Laboratory Vanderbilt School of Engineering Sneak Preview Mk2

Intelligent Robotics Laboratory Vanderbilt School of Engineering Mass production  Actuator is single wire  n loop  coil tension equalized  each end crimped to wire  Epoxy to attach “tendon”  Coated for biological applications  Portable battery and controllers

Intelligent Robotics Laboratory Vanderbilt School of Engineering Cost  1 meter each  Flexinol HT 375  Flexinol HT 200  Flexinol HT 100  Flexinol HT 037  Microprocessor X 2  Multiplexer  Voltage Amplifier  Wiring  Epoxy  Cable  Total  $22.95  $19.95  $17.95  $16.95  $50.00  $8.00  $10.00  $8.00  $171.80

Intelligent Robotics Laboratory Vanderbilt School of Engineering Project Status  Completed work  Study properties of motor wire  Calculate efficiency of passive cooling  Develop Structure and Control for the device  Design test bed  Build actuator  Current Work  Finish neural network controller

Intelligent Robotics Laboratory Vanderbilt School of Engineering Future Work  Examine biocompatibility  Calculate mass production costs  Evaluate production and market feasibility

Intelligent Robotics Laboratory Vanderbilt School of Engineering Questions?