Neural network based dynamic modeling of flexible-link manipulators with application to the SSRMS

This paper presents an approach for dynamic modeling of flexible-link manip ulators using artificial neural networks. A state-space representation is c onsidered for a neural identifier. A recurrent network configuration is obt ained by a combination of feedforward network architectures with dynamical elements in the form of stable filters. To guarantee the boundedness of the states, a joint PD control is introduced in the system. The method can be considered both as an online identifier that can be used as a basis for des igning neural network controllers as well as an offline learning scheme to compute deflections due to Link flexibility for evaluating forward dynamics . Unlike many other methods, the proposed approach does not assume knowledg e of the nonlinearities of the system nor that the nonlinear system is line ar in parameters. The performance of the proposed neural identifier is eval uated by identifying the dynamics of different flexible-link manipulators. To demonstrate the effectiveness of the algorithm, simulation results for a single-link manipulator, a two-link planar manipulator, and the Space Stat ion Remote Manipulator System (SSRMS) are presented. (C) 2000 John Wiley & Sons, Inc.