K.W. Buffinton, J.A. Schwab, C.M. Hubicki, S.A. Freeman, and M.C. Berg (USA)
Pulse-width control, robotics, Coulomb friction, high precision
Pulse-width control, when applied to single degree-of freedom systems, has been shown to be very effective in achieving high-precision positioning in systems subject to the undesirable effects of Coulomb friction and stiction. This paper describes continuing work into the application of pulse-width control to systems with more than one degree of freedom. Specifically, this research focuses on the development and implementation of adaptation schemes for tabular pulse-width control. Results are presented based both on simulations and experiments using a two degree-of-freedom prismatically jointed manipulator developed at Bucknell University. These results show that Normalized Least Mean Square (NLMS) adaptation of tabular pulse-width control consistently achieves positioning accuracies equal to that of the sensing devices employed. Moreover, adaptive tabular pulse-width control is shown to be effective with relatively small tables even with significant parameter variations and problematic system behavior.
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