Biomimetic sensing for robotic manipulation
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Biomimetic Sensing for Robotic Manipulation. Neil Petroff, Ph. D. Candidate University of Notre Dame. Lerner Research Institute Cleveland, OH December 8, 2005. Outline. Me on Me Grasping biology as motivation for current work Robotic Manipulation Nonholonomic motion planning

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Biomimetic Sensing for Robotic Manipulation

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Biomimetic sensing for robotic manipulation

Biomimetic Sensing for Robotic Manipulation

Neil Petroff, Ph. D. Candidate

University of Notre Dame

Lerner Research Institute

Cleveland, OH

December 8, 2005


Outline

Outline

  • Me on Me

  • Grasping

    • biology as motivation for current work

  • Robotic Manipulation

    • Nonholonomic motion planning

    • Motion planning for stratified systems

  • Open-Chain Manipulators

    • Forward kinematics

    • Inverse kinematics

  • Biomimetic Robot Sensors

    • Vision, touch

  • Control Perspective on Deep Brain Stimulation

  • The Rest of the Story


Hand orthosis

Hand Orthosis

Target Group: C5 - C7 SCI

  • 3 Grasps

    • Fingertip, key, cylindrical

  • Increase Autonomy

  • Mercury Orthotics

    • Rehabilitation technology

      • therapeutic

      • quality of life


Grasping

Grasping

  • Interaction

  • Creation

  • Task Execution

Grasping Hand Orthosis Robotic Manipulation Fuzzy Logic Open-Chain Manipulators Biomimetic Robot Sensors Work to Date


Grasping1

Grasping

RobotsHumans

Poor at fine motiongood at fine motion

No feedback vision, proprioception

structured adaptive

precise robust

rapid slow

strong variable

stamina need to rest

Can we improve robotic manipulation by imbuing robots with useful human characteristics?

Grasping Hand Orthosis Robotic Manipulation Fuzzy Logic Open-Chain Manipulators Biomimetic Robot Sensors Work to Date


Biological motivation

Biological Motivation

  • Haptic Recognition

    • Force feedback

  • Compliance is Useful for Manipulation

  • Brain Model

    • Fuzzy logic

  • Hierarchical Control

Grasping Hand Orthosis Robotic Manipulation Fuzzy Logic Open-Chain Manipulators Biomimetic Robot Sensors Work to Date


Biological control loop

Biological Control Loop

current

configuration

desired

task

motion planning

algorithm

inverse

kinematics

encoder

counts

PID

Robot

fuzzy

supervisor

trajectory

adjustment

sensor

readings

encoder

counts


Testbed

Testbed


Robotic motion planning

Robotic Motion Planning

  • Steering Using Piecewise Constant Inputs

    • This is a geometric analysis

    • Provides a systematic approach for establishing controllability

    • Applicable to underactuated systems with nonholonomic constraints

    • Exact for nilpotent systems of the form

      • Driftless

      • Not all gi’s may exist

      • a system is nilpotent if all Lie brackets greater than a certain order are zero

    • Lie bracket motions

      • allows the system to move in a new direction


Lie bracket motions

Lie Bracket Motions

Flow along g3 can be approximated by flowing along g1 and g2

Higher order brackets can be generated, e.g.


Example

Example

Parallel parking a car


Example1

Example

Car equations

l

{

{

g1

g2

Extended System


Car simulation

Car Simulation


Why didn t it work

Why Didn’t it Work?

  • The Car Model is not Nilpotent

    • g5 points in the same direction as g3

    • Motion along lower order brackets induces motion along higher order brackets

  • Solution

    • Iterate

    • Feedback nilpotentization

  • Other Drawbacks

    • Small Time or Small Inputs

      • obstacle avoidance

    • Open Loop

      • highly susceptible to modeling errors

      • no error correction


Stratified systems

Neither finger in contact

stratum

S1

M=S0

S2

g2,2

g2,1

g1,2

-g1,1

finger 2 in contact

-g2,1

finger 1 in contact

g1,1

S

1

2

Both fingers in contact

Stratified Systems

  • Extends motion planning algorithm to systems with discontinuities

    • Intermittent contact

      • locomotion

      • manipulation


Control architecture

Control Architecture

Desired

task

motion planning

algorithm


Open chain manipulators

Product-of-exponentials formula

A configuration is of the form

Open-Chain Manipulators

Forward kinematics

P

s

T


Inverse kinematics

Inverse Kinematics

The inverse kinematics solution is not unique

1

1

1

1


Inverse kinematics1

pw - pb

Inverse Kinematics

  • PUMA geometry makes an analytical solution tractable


Inverse kinematics2

Inverse Kinematics

14” diameter circle


Control architecture1

Control Architecture

Desired

task

motion planning

algorithm

inverse

kinematics

current

configuration

encoder

counts

PID

Robot

fuzzy

supervisor

current

counts


Biomimetic sensing

Biomimetic Sensing


Force sensors

Force Sensors

  • Feedback at Finger/Object Junction

  • Piezoelectric

    • Used in biomedical testing

    • Compliant

    • Tend to drift under static load

  • Flexiforce Sensor


Finding an object

Finding an Object


Control architecture2

Control Architecture

current

configuration

desired

task

motion planning

algorithm

inverse

kinematics

encoder

counts

PID

Robot

fuzzy

supervisor

trajectory

adjustment

sensor

readings

encoder

counts


Summary

Summary

  • So Far

    • Built a closed loop system to perform robotic manipulation

      • stratified motion planning

      • inverse kinematics solution

      • force feedback

  • To Do

    • Manipulation

      • Currently working on simulation

      • apply to robots


Control perspective on dbs or what the heck am i doing here

Control Perspective on DBS(or “What the heck am I doing here?”)

  • Underlying manipulation technique is a geometric approach to nonlinear controls

  • Nonlinear control lies at the forefront of modern control methods

  • One of the most intriguing aspects of nonlinearity is that of chaos

  • Nonlinear control techniques have been used to suppress cardiac arrythmia, a chaotic process

  • Is neuron transmission chaotic?

    • at the heart of successful treatments using deep brain stimulation is the ability to control chaos

  • Robust and nonlinear control techniques provide an analytical foundation on which to study such systems

  • Soft computing techniques provide an additional approach that while not at rigorous may yield equal or better results


Open questions on dbs

Open Questions on DBS

  • By approaching DBS from a control Theory Standpoint, Can We

    • Control with external stimulation locally?

  • Filter the signals?

    • Characterize which signals cause which disruptions

      • stimulation can suppress dyskinesia

      • tremors tend to lessen during movement

  • Keep symptoms from returning with fatique?

    • Muscle spasticity

  • Completely eliminate meds?


The rest of the story

The Rest of the Story

  • 54,000 SCI

    • Additional 2,800 / yr at C5 – C6 level

  • Parkinson’s affects 750,000 – 1 million people in the U.S.

  • Other Pathologies

    • Hemiplegic stroke

    • Multiple sclerosis

    • Muscular dystrophy

  • Rehab

  • Funding

    • Competition for startup money

  • Who Can Pay?

    • Hand Mentor from KMI

      • $3,950

      • Coverage from private insurance companies in only 2 states

      • Currently no medicare coverage

    • State of Indiana Home and Community Based Care Act

      • Provides funding for community and home-based care

      • 2002: 84 / 16

      • Medicaid savings of $1,300 per client per month

      • Savings on the order of 3:1 when compared with institutional care


My plea

My Plea

  • As researchers, I believe we have a responsibility to pursue noble goals

  • Obligation of the Engineer

    • “… conscious always that my skill caries with it the obligation to serve humanity …”

  • Hippocratic Oath

    • “I will remember that I do not treat a fever chart, a cancerous growth, but a sick human being, whose illness may affect the person's family and economic stability. My responsibility includes these related problems, if I am to care adequately for the sick.”

    • “will remember that I remain a member of society, with special obligations to all my fellow human beings, those sound of mind and body as well as the infirm.”


On a lighter note

On a Lighter Note


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