Domo: Manipulation for Partner Robots

Aaron Edsinger

MIT Computer Science and Artificial Intelligence Laboratory

Humanoid Robotics Groupedsinger@csail.mit.edu

Robots That Can Work Alongside Humans

• Built for human environments

• Safety in the human workspace

• Humanoid body to work with everday objects

• Perform tasks that are important to people using natural strategies with everyday objects

Confronting Unstructured Environments

Creating Robust Manipulation Interactions in Unstructured

Environments

• Let the body assist perception

• Passive compliance and force control

• Highly integrated behavior-based architecture

• Perceptual prediction through efference-copy models

• Learn task-relevant features of objects instead of using full 3D models

•29 active degrees of freedom (DOF)

•Two 6 DOF force controlled arms using Series Elastic Actuators

•Two 6 DOF force controlled hands using SEAs

•A 2 DOF force controlled neck using SEAs

•Stereo pair of Point Grey Firewire CCD cameras

•Stereo Videre STH-DCSG-VAR-C Firewire cameras

•Intersense 3 axis gyroscope

•Two 4 DOF hands using Force Sensing Compliant (FSC) actuators

•Embedded brushless and brushed DC motor drivers

•5 Embedded Motorola 56F807 DSPs running a 1khz control loop

•4 CANBus channels providing 100hz communication to external computation.

•49 potentiometers, 7 encoders, 24 tactile sensors, 12 brushless amplifiers, 17 brushed amplifiers, 12 sensor conditioners embedded on-board

•An estimated 500 fabricated mechanical components and 60 electronics PCBs

•12 node Debian Linux cluster running a mixture of C/C++/Python and utilizing the Yarp and pysense robot libraries.

•Weight: 42lbs. Height: 34" tall. Arm span: 5' 6"

Domo

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

Behavior Based ArchitectureArm Behaviors Head Behaviors

Series Elastic and Force Sensing Compliant Actuators

F=-kx

Series Elastic and Force Sensing Compliant Actuators

•Mechanically simple

•Improved stability

•Shock tolerance

•Highly backdrivable

•Low-grade components

•Low impedance at high frequencies

Passive and Active Compliance

Series Elastic Actuator Force based grasping

Exploit interaction forces at the hand as an additional perceptual modality

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

hT fJ

qqqqq

},,,{

},,,{

4321

4321

Upper 4 DOF of each arm.

Sensed joint torque

Sensed joint angle

Jacobian relates hand forces to joint torques

MotGravAccExoEgo

Mot

Acc

Exo

Ego

Sensed torque

Bimanual interaction torque

External interaction torque

Mass Acceleration torque

Motor torque

Z n

Z 2

Z 1

EFF

+- EC

Exo

Ego

ExoGrav

Mot

Commanded torqueSensed torque

Predicted torque

)(),()( qGqqVqqM Inverse dynamics

qqMAcc )(

0),( qqV Coriolis and Centrifugal

0

)(qGGrav

Efference Copy Model•Simplified inverse dynamic model of arm

•Model predicts normally occurring torques during reaching

•Use the prediction to amplify the salience of interaction torques (external and bimanual)

(von Holst, 1973)

Mot

Known (Commanded torque)

Known

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

Learning About Tool Use

•Motion feature points for tip detection•3D position estimation using probabilistic model

Estimation of Tool Position in the Hand

Autonomous Detection and

Control ofHuman Tools