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Implementation of a three degree of freedom, motor/brake hybrid force output device for virtual environment control tasksThe advent of high resolution, physical model based computer graphics has left a gap in the design of input/output technology appropriate for interacting with such complex virtual world models. Since virtual worlds consist of physical models, it is appropriate to output the inherent force information necessary for the simulation to the user. The detailed design, construction, and control of a three degree freedom force output joystick will be presented. A novel kinematic design allows all three axes to be uncoupled, so that the system inertia matrix is diagonal. The two planar axes are actuated through an offset gimbal, and the third through a sleeved cable. To compensate for friction and inertia effects, this transmission is controlled by a force feedforward and a closed force feedback proportional loop. Workspace volume is a cone of 512 cubic inches, and the device bandwidth is maximized at 60 Hz for the two planar and 30 Hz for the third axis. Each axis is controlled by a motor/proportional magnetic particle brake combination fixed to the base. The innovative use of motors and brakes allows objects with high resistive torque requirements to be simulated without the stability and related safety issues involved with high torque, energy storing motors alone. Position, velocity, and applied endpoint force are sensed directly. Different control strategies are discussed and implemented, with an emphasis on how virtual environment force information, generated by the MIT Media Lab Computer Graphics and Animation Group BOLIO system, is transmitted to the device controller. The design constraints for a kinesthetic force feedback device can be summarized as: How can the symbiosis between the sense of presence in the virtual environment be maximized without compromising the interaction task under the constraints of the mechanical device limitations? Research in this field will yield insights to the optimal human sensory feedback mix for a wide spectrum of control and interaction problems. A flexible research tool that is designed as an easily reproducible product prototype has been constructed to explore the variety of possible force interaction.
Document ID
19950007645
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Russo, Massimo (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Tadros, Alfred (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Flowers, Woodie (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Zeltzer, David (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1991
Publication Information
Publication: NASA. Ames Research Center, Human Machine Interfaces for Teleoperators and Virtual Environments
Subject Category
Man/System Technology And Life Support
Accession Number
95N14058
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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