0
TECHNICAL PAPERS

Induced Master Motion in Force-Reflecting Teleoperation

[+] Author and Article Information
Katherine J. Kuchenbecker

Telerobotics Lab, Mechanical Engineering Department, Stanford University, Stanford, CA 94309katherin@stanfordalumni.org

Günter Niemeyer

Telerobotics Lab, Mechanical Engineering Department, Stanford University, Stanford, CA 94309gunter.niemeyer@stanford.edu

J. Dyn. Sys., Meas., Control 128(4), 800-810 (Apr 01, 2006) (11 pages) doi:10.1115/1.2364011 History: Received October 19, 2004; Revised April 01, 2006

Telerobotic systems have persistently struggled to provide users with realistic force feedback; high-frequency contact transients convey important information about the remote environment but are typically attenuated to avoid the contact instability they incite. This undesirable behavior can be traced to high-frequency induced master motion, movement of the master device that is caused by force feedback rather than user intention. Such motion is interpreted as a position command to the slave, closing an internal control loop that is unstable under high gain. This paper examines the phenomenon of induced master motion in position-force teleoperation, presenting a new approach for achieving stable, high-gain force reflection using model-based cancellation. Requirements for the model of the induced motion dynamics and methods for its characterization are described, focusing on successive isolation of inertial and connecting elements. The sixth-order nonlinear model obtained for a one-degree-of-freedom user-master system is validated and then tested in a cancellation controller. Canceling high-frequency induced master motion during teleoperation is shown to improve the stability of impacts, allowing significantly higher force reflection levels and a more authentic user experience.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

A telerobotic system connects the user to the environment via master and slave robots

Grahic Jump Location
Figure 2

The master’s long dynamic chain connects the user to the controller

Grahic Jump Location
Figure 3

In position-force control, the slave is commanded to track the master’s position, and the master mechanism recreates tip interaction forces for the user

Grahic Jump Location
Figure 4

Display of a scaled, prerecorded force profile to a user executing a constant motion with a 1-dof master. Increasing the force scale λ generates motor movement that is not intended by the user.

Grahic Jump Location
Figure 5

Motion induced by the force feedback xmi superimposes with the user’s voluntary motion xmv at the master motor. The electrical, mechanical, and biomechanical dynamics of the user-master system Gi govern the pathway of induced master motion, and the user’s cognitive processes Gv determine the voluntary motion.

Grahic Jump Location
Figure 6

Position-force control with three compensation options: local derivative feedback on master position via b(d∕dt), position command filter Kμ, and force feedback filter Kλ

Grahic Jump Location
Figure 7

High-frequency induced master motion can be canceled using the model Ĝi,hf

Grahic Jump Location
Figure 8

Successive isolation of the user-master system progresses from the force command through the motor, cables, drum, linkage, handle, and user

Grahic Jump Location
Figure 9

Single-axis position-force telerobotic testbed

Grahic Jump Location
Figure 10

Nonlinear lumped-parameter model of the user-master system. The κ parameters signify nonlinear stiffness relationships, and the C parameters indicate Coulomb friction.

Grahic Jump Location
Figure 11

When held by a user, the system exhibits a well-damped resonance at 70Hz, in which the handle vibrates against the flesh of the user’s hand

Grahic Jump Location
Figure 12

The full model accurately predicts induced master motion during open-loop display of a prerecorded force profile, providing a smooth estimate of user intention, x̂mv

Grahic Jump Location
Figure 13

Force feedback Ff and slave position command xc with and without cancellation for a range of λ values, keeping μ=1. Contacts are stabilized by canceling induced master motion from the measured master position xm, using the model’s real-time estimate x̂mi.

Grahic Jump Location
Figure 14

Cancellation of induced master motion is implemented via C5 in the general architecture for teleoperation

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In