Creating Robust Manipulation Interactions with Imperfect Actuators and Sensors

• Passive and active compliance with SEAs• Highly integrated set of behaviors through

behavior-based architecture• Perceptual saliency amplification through

efference-copy models• Exploit rich force interactions which naturally

occur during exploration as a learning opportunity

Passive and Active Compliance

Series Elastic Actuator Force based grasping

Exploiting Force Interactions for Learning

1. Exploration behavior1. Decrease shoulder

stiffness on contact2. Localizes exploration

around object3. Creates rich interaction

forces

2. Learning1. Force based

representation of object affordances

2. Model of natural interaction forces

3. Scaffold to richer manipulation abilities

Force Based Efference-Copy Model

Y

Z

X

m 1r

m 0r

m 0l

m 1l

0r

1r

2r

3r

4r

5r

0l

1l

2l

3l

4l

5l

1h

0h

6r

7r

8r

9r

6l

7l

8l

9l

Force Based Efference-Copy Model

• Predictive forward model of the joint torques

• Amplifies salient interaction forces during manipulation

• Torque predictions made using simple kinematic and mass model

Z n

Z 2

Z 1

EFF

+- EC

Exo

Ego

ExoGrav

MotCommanded torqueSensed torque

Predicted torque

Detection of Self-Induced Hand Forces

Interaction forces at hands are approximately equal and opposite

Interaction forces present

Interaction forces not present

Detection of Interaction Forces

Efference copy model generates torque prediction.

Torque prediction errors drivevisual attention system.

Ballistic reaching: prediction error

External forces: prediction error

Systems Development: Behavior Based Architecture

Arb

Wire

Overwrite

Max

Static

Arbitrator

Queue

Stack

Scheduler

Module

Thread

Monostable

•Architectural primitives allow tightly integrated system•100hz scheduler •Dynamic arbitration•12 node Linux cluster•~50 threads currently

Homeostat

VisualExploration

HandServoLeft

HandServoRight

HandLookRight

HandLookLeft

FaceTrack

BlobTrack

CartesianTrack

Fixation

VisualServo

Kinematics

ARB

PoseController TrackingController

ARB

BallTrack

ARB

I

ARB

Zero

I I I

FixationReach

CartesianTrack

ARB

ForceController VSpringController

ZeroG

ARB

VisualServoFingers

VisualServoProximity

I X

X

RelaxPose

ShowObject

StiffnessModulation

s

s

sx x

s

ExamplesArm Behaviors Head Behaviors

VisualExploration

HandServoLeft

HandServoRight

HandLookRight

HandLookLeft

FaceTrack

BlobTrack

CartesianTrack

Fixation

VisualServo

Kinematics

ARB

PoseController TrackingController

ARB

BallTrack

ARB

I

ARB

Zero

I I I

FixationReach

CartesianTrack

ARB

ForceController VSpringController

ZeroG

ARB

VisualServoFingers

VisualServoProximity

I X

X

RelaxPose

ShowObject

StiffnessModulation

s

s

sx x

s

ExamplesArm Behaviors Head Behaviors