INTRO TO PO10029: CONTROL ENHANCEMENTS FOR AIR MUSCLE BIOMIMETIC HANDDr. Kathleen Lamkin-Kennard

Sept. 14, 2009

PROJECT BACKGROUND

Started in 2007 as group of projects to see if we could recreate hand motions using air muscles

Projects have become part of larger scale research program to create biomimetic robotic platforms

Multiple projects involved (not just senior design) M.S. theses: Scalability and kinetic study of

finger and hand motions, underwater actuation, development of electroactive polymers as actuation mechanisms, development of controls and simulation platform for design purposes

Senior design: PO 8023, PO 8024, PO 9023, PO 9029

LONG-TERM GOALS OF BIOMIMETIC RESEARCH PROGRAM

Recreate human motions for purpose of developing dextrous manipulator platforms

Develop platform capable of operating at different scales E.g. microscale, large industrial scale

Develop platform capable of integrating with various controls platforms E.g. glove control

Develop platform that can be used in variety of environments

BIOMIMETIC RESEARCH PROGRAM TO DATE

Focused on mimicking hand and finger motions Future will extend to other limbs (individual and

coordinated) Focused on different actuation mechanisms

Primarily air muscles Also electroactive polymers

Now focusing on creation of a development platform for mechanical design and controls This is where you come in!!!

Future applications: Remote surgery, large scale maintenance,

remote detonation, assistive exoskeletal devices, etc.

RATIONALE FOR CREATION OF DEVELOPMENT PLATFORM

Devices developed to date have been developed largely as “one of” devices No common architecture for mechanical

development or controls Built using trial and error approach

Want to come up with method for simulating device feasibility prior to actual fabrication Reduce cost, development time

Want to be able to test controls on virtual devices ahead of time Reduce development time, cost Enable testing of controls without physical

hardware

WHAT WILL DEVELOPMENT PLATFORM CONSIST OF?

To start: 3D kinematic model of mechanical designs (likely

done in SolidWorks) Controls software (likely done in LabVIEW)

Capable of driving both physical and virtual prototypes Integration of controls software with kinematic

models (ie. Controls software should be capable of driving virtual model of mechanical design)

In the future: 3D kinetic model of mechanical designs

SO WHERE DO YOU COME IN?? BACK TO YOUR PROJECT…

Your team will be implementing the development platform Will use biomimetic hand developed by PO 9023

and kinematic models of the physical hand Can verify platform capabilities since we have a

working physical prototype Will also be implementing closed loop

feedback capabilities on physical hand

YOUR PROJECT

Design and implement controls software that can be applied to both physical and virtual prototypes Physical prototype - existing hand platform

developed PO9023 (AS IS!!!) Virtual prototype will be developed using

SolidWorks and the LabVIEW Mechatronics tool kit. Will need to implement closed loop

displacement feedback on current hand platform Linear and rotary potentiometers exist on hand and

software exists to obtain closed loop feedback, but the previous team was unable to get the closed loop feedback working

MY CUSTOMER NEEDS Maintenance and repair of existing hand hardware developed by PO9023. Maintenance and repair will be

necessary to meet customer needs below, however improvements to the existing mechanical hardware are beyond the scope of this project.

Implement closed loop feedback control on robotic hand developed by PO9023. Displacement feedback must be obtained using existing linear and rotary potentiometers on existing hand. Displacement feedback will be used to drive mechanical hardware to a target position. Target position will be input into LabVIEW as a percentage of maximum displacement in each direction in 3D space. Output will be motion of the physical hardware. The team will be responsible for benchmarking the capabilities of the existing hand with regards to degrees of freedom and displacement to determine maximum displacement capabilities in each direction. Notes: Force characterization is beyond the scope of this project. Also, no target specifications are given from the customer for displacements or velocities to be achieved since the team is limited to working with the existing hardware “as is”.

Build kinematic model of existing hand hardware using SolidWorks/Cosmos Motion Builder. The kinematic model must have identical kinematic degrees of freedom as the existing mechanical hand hardware developed by PO9023. However, it does not have to be an exact geometric configuration (e.g. cables in kinematic model may be reduced to alternative controllable mechanism, etc.). Kinematic model must output displacement outputs equivalent to the outputs obtained from the linear and rotary potentiometers on the physical hardware.

Drive kinematic model from LabView using the LabVIEW/ SolidWorks Mechatronics Toolkit (http://zone.ni.com/devzone/cda/tut/p/id/6183). The kinematic model in SolidWorks must accept the same inputs from LabVIEW used to drive the physical mechanical hand (ie. inputs in LabVIEW = % max deflection and outputs = deflection of SolidWorks kinematic model). 3D positions from SolidWorks will then be transmitted back to LabVIEW in a manner analogous to the feedback that the potentiometers from the physical device would provide back to LabVIEW. Note: this simulated closed loop feedback between SolidWorks and Labview may be done manually if limited by software capabilities.

Quantitative analysis comparing displacements of mechanical hand to virtual model. Method for comparison will be determined by team. Must include error analysis.

A detailed documentation package describing the control system, kinematic model, and interface delivered. Starting from a features required viewpoint, system architecture, and module descriptions. This is essential as the management team views this as a starting point for future projects.

Desired (x,y,z,Θ) position

LabVIEW

Cosmos Motion Builder

SolidWorks Kinematic Model

Displacement of kinematic model

on screen

Control boards, relays

Open, close valves; Fill air

muscles

Displacement of physical hand

model

Position feedback from SolidWorks**

Position feedback from potentiometers

Overall System Architecture for PO10023

** May be done manually, if necessary, due to software limitations

KEY DELIVERABLES LabVIEW software capable of driving existing mechanical

hand hardware and receiving feedback from existing rotary and linear potentiometers

Documented analysis that existing hardware is capable of receiving feedback from linear and rotary potentiometers on existing hand. Team must provide demonstration that a target position can be input into LabVIEW and mechanical hardware will respond appropriately.

Software assembly in SolidWorks capable of reproducing kinematic motion of physical hand hardware

LabVIEW software capable of driving SolidWorks kinematic model to target positions. Team must provide demonstration that a target position can be input into LabVIEW and kinematic model will respond appropriately.

Quantitative analysis comparing mechanical hand motions to virtual kinematic model. Must include error analysis.

WHAT DOESN’T PROJECT INCLUDE?

Investigation of strength capabilities Life cycling – assume air muscles are

essentially a disposable item Modeling of air muscles (will get information

on how they work from Sylvan Hemingway) ASL Extensive air muscle testing Improvements to existing hand Kinetic modeling

RESOURCES

Sylvan Hemingway (M.S. student) – air muscle capabilities

Yateen Shembade (M.S. student) – integration of SolidWorks and LabVIEW

Melissa Monahan (M.S. student) – hand modeling

Scott Kennard – SolidWorks modeling LabVIEW mechatronics experts – need to

establish this relationship Existing data for air muscles

Extensive testing of muscles has been done previously

CAUTIONS Benchmarking of the existing system will be a critical

set of investigations in the first three weeks Capability of the system- degrees of freedom,

displacements- what can the hand system do? Understanding of human hand physiology and

capabilities of existing hand. Define capabilities of existing hand in terms of common physiological language.

Identification of Mechatronics toolkit software capabilities will also be a critical investigation to be accomplished in the first three weeks Software is an ALPHA version!

Senior Design process is helpful, but don’t get bogged down in the process and documentation You still need to do the engineering!