A parallel fuzzy-controlled flexible manipulator using optical tip feedback

Investigation and development of a fuzzy-controlled highly non-linear two-axis manipulator with a single-flexible link using a novel patented optical tip displacement feedback is described. The controller comprises a parallel fuzzy supervisor that is used to alter the derivative term of a linear classical PD controller, which is updated in relation to the measured tip error and error rate. Implementation of the supervisory fuzzy controller is described using both serial and parallel operation on transputers. The design of the fuzzy rules was made with a modified closed-loop phase-plane method. The design approach results in a controller implementation that uses only 14 rules and is suitable for cheaper CPU-constrained and memory-challenged embedded processors. The benefits introduced by this procedure include a method to decide where and when the action takes effect in the controller and a greatly reduced rule base. The parallel operation achieved rise times of 0.033 s and settling times of 0.064 s for a payload of 0.7 kg considerably better than other workers did. An 128% increase in payload, 73.5% faster settling time and a reduction of steady-state error of over 50% were achieved using fuzzy control over its classical counterpart. (C) 2003 Published by Elsevier Science Ltd.