Optimal nonlinear controller design for flexible robot manipulators with adaptive internal model

Developing nonlinear adaptive and robust controllers for a two-link flexible robot arm is the main objective of this research. The dynamic state feedback controller is used to achieve robust regulation of the rigid modes as well as suppression of elastic vibrations. However, the control of highly nonlinear multi-link flexible arms is subject to uncertainties caused by backlash, payload changes and external disturbances. Therefore adaptive and robust control of multi-link flexible arms is a challenging problem. The internal model approach is adaptively tuned up for unknown disturbances, parallel with a robust stabiliser. The stabiliser part of the controller is optimised with a new evolutionary algorithm.Publisher's Versio

End-effector trajectory control in a two-link flexible manipulator through reference joint angle values modification by neural networks

The basic difficulty in the control of flexible link manipulators stems from the fact that the link deflections cannot be controlled directly. Since the number of control inputs, applied by the actuators, is less than the total number of variables to be controlled, control approaches aiming at the suppression of deflections and vibrations are generally insufficient. Another possible approach is to determine new joint trajectories to minimize the error of the end-effector in the operational space. In this paper, a neural network is designed to compute incremental changes for the reference values of the joint angles to achieve successful tip tracking in the operational space. Tip position errors in the x- and y-directions are utihzed as inputs to the neural network. The cost function, which is minimized in training the neural network, is also chosen as the sum of squares of the tip position error in both directions. Joint angle control is provided by a PD controller. Simulations are carried out to evaluate the performance of the neural-network-based trajectory tracking method, and the results are depicted in both joint and operational spaces.Publisher's Versio

Optimal nonlinear control of two-link flexible arm with adaptive internal model

The control of highly nonlinear multi-link flexible arms is subject to uncertainties caused by backlash, payload changes and external disturbances.Therefore, adaptive and robust control of multi-link flexible arms is a challenging problem.In this paper, the internal model approach is adaptively tuned up for unknown disturbances, parallel with a robust stabilizer. The stabilizer part of the controller is optimized with a new evolutionary algorithm.Publisher's Versio