Date of Award

1995

Degree Name

M.S. in Electrical Engineering

Department

Department of Electrical and Computer Engineering

Abstract

Haptic feedback devices for virtual reality and telerobotics applications reproduce physical sensations to a human operator who interacts with a virtual or remote environment. Motors or other actuators reflect forces of interaction to the arms, hands, and fingers of the user. Tactile feedback devices stimulate the cutaneous tactile sense either to mimic skin touches in the reflected environment or to give a cue to the operator that he or she is encountering virtual forces. Real manipulation and haptic exploration rely on the seamless integration of the cutaneous tactile and force subcomponents of the sense of touch. Any human interface that replicates only one of these two subcomponents will provide an incomplete, sense of “presence” in the reflected environment. The sense of “presence” is defined as the transparency of the operator interface with the reflected environment. The user with a good sense of presence will perceive the reflected environment rather than the interface itself. An imperfect subjective experience will likely lead to degradations in objective measures such as task completion times, errors, forces of interaction, and object discrimination. This thesis describes the development of custom-built tactile feedback hardware and its integration with an available force-reflecting haptic interface. Design requirements were motivated strongly by the characteristics of the human tactile sense as well as the biomechanical characteristics of the human finger. The work explores the feasibility of various actuators, and selects a small solenoid actuator for application in a closed-loop force control tactile feedback system. An adaptive PI algorithm using continuously variable gain scheduling helps to compensate for nonlinearities in the solenoid actuator. The system demonstrates adequate closed-loop control, but the mass added to the force-reflecting haptic interface proves less than optimal. Design suggestions for future prototypes may reduce the mass added by the tactile feedback hardware by over 30%. The work concludes with recommendations for psychophysical research that will increase understanding of human performance in tasks using haptic feedback devices.

Keywords

Tactile sensors, Human-machine systems, Robots Control systems, Feedback control systems, Adaptive control systems

Rights Statement

Copyright © 1995, author

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