Active compensation of flexibility in belt-driven drivetrains

by Robert B. Gorbet and Scott A. Bortoff


Abstract: This paper discusses a novel method to compensate the effects of flexibility in belt-driven drive trains. Such drives are found in robot manipulators, for example, where drive flexibility is undesirable. In some situations, bandwidth limitations can make flexibility dif ficult to compensate using the primary actuator. In others, the control for the primary actuator is pre-defined and cannot be altered easily. We have introduced a second actuator, called a dancer, which applies a force to the belt at a point between the pulleys. Using backstepping to control belt tension with the dancer, the system transfer function from input pulley to output pulley can be made exactly rigid. The performance of the dancer-actuated system compares favourably with a composite controller designed for the original belt drive.


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