NEURAL-NET ROBOT CONTROLLER - STRUCTURE AND STABILITY PROOFS

A multilayer neural net (NN) controller for a general serial-link robo t arm is developed. The structure of the NN controller is derived usin g a filtered error approach. It is argued that standard backpropagatio n tuning, when used for real-time closed-loop control, can yield unbou nded NN weights if: (1) the net can not exactly reconstruct a certain required control function, (2) there are bounded unknown disturbances in the robot dynamics, or (3) the robot arm has more than one link (i. e. nonlinear case). On-line weight tuning algorithms including correct ion terms to backpropagation, plus an added robustifying signal, guara ntee tracking as well as bounded weights. The correction terms involve a second-order forward-propagated wave in the backprop network.