Design and Control of a 3-D Wearable Cobot

Cobots are specially designed robots that use continuously variable transmissions (CVTs) instead of traditional motor driven joints. With a cobot, the human experiences haptic effects through physical contact with the cobot’s end-effector. Safety is maintained through shared human-cobot control where the cobot velocity vector is split into 1) a speed that is proportional to the human’s input power and 2) a direction that is determined by the CVTs. We believe that cobots are an attractive choice for telerobotic master controllers because they are safe in contact with humans and are able to produce stable high quality virtual surfaces that can constrain the motion of the master to directions suitable for telerobotic task completion. This paper presents the design and control of a 3-D arm-wearable cobot for telerobotic operation. In our design a master cobot attaches to the user’s arm so that the user’s natural arm motions can be sensed and transmitted as the control signals for the slave robot. Furthermore, since the wearable arm is a cobot, virtual motion constraints may be safely placed on the master. Herein we describe the design of the wearable arm cobot and introduce a novel power assist mode, which makes it possible to control the cobot’s position relative inertia. The effectiveness of this control mode is investigated using simulations.Copyright © 2005 by ASME

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