Carnegie Mellon Robotics Institute
|In this report, a composite control scheme for the control of robot manipulators is proposed.
Due to the modeling error or environmental uncertainties, robot motion may present a significant positioning error by using a conventional Computer-Torque Method. To improve tracking capability of robot manipulators, sliding mode control and nonlinear control algorithms have been introduced, but computation is costly, and thus a fast motion execution using simple computer sources is impossible.
To solve this problem, we present a composite control algorithm to control robot motion combining a discrete feedforward component and a continuous feedback component. The discrete feedforward component provides a nominal torque computed using the robot dynamics and compensates for dynamic coupling between the links. This part can be updated in a large sampling time, and can be computed off-line generally, thus real time computation is decreased. The continuous feedback control component uses a structure of Variable Structure System and provides a robust control to disturbances during the sliding mode. This part can be digitally implemented using a short sampling time, and thus a fast motion of a multi-degree freedom robot manipulator can be executed by using a simple computer, or even a single board computer with an 8-bit CPU.
The stability of the proposed multiple-rate control scheme is proven in the paper and efficiency of the control scheme has been demonstrated by simulations of a three-link robot subject to parameter and payload uncertainties.
Grant ID: N00014-81-0503, N00014-90-J-1656
Associated Center(s) / Consortia: Vision and Autonomous Systems Center
Number of pages: 24
|Ju-Jang Lee and Yangsheng Xu, "A Composite Discrete/Continuous Control of Robot Manipulators," tech. report CMU-RI-TR-91-09, Robotics Institute, Carnegie Mellon University, April, 1991|
author = "Ju-Jang Lee and Yangsheng Xu",
title = "A Composite Discrete/Continuous Control of Robot Manipulators",
booktitle = "",
institution = "Robotics Institute",
month = "April",
year = "1991",
address= "Pittsburgh, PA",
|The Robotics Institute is part of the School of Computer Science, Carnegie Mellon University.|
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