| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 107 === A novel control scheme called enhanced super twisting sliding mode-based
chattering-free adaptive neural network controller is proposed in this study to deal with disturbances and uncertainties in controlling a 6-DOF manipulator (ABB IRB 140 robot). In our preliminary study, it can be observed that a high-order and complex dynamic system, like 6-DOF manipulators has shown difficulties in eliminating chattering phenomena, especially in the last joints (the fifth and the sixth joints) even within the use of modern saturation sliding mode term or second order sliding mode control laws. In general, the proposed controller is to use adaptive neural network control and modified second order super twisting sliding mode control to learn and to compensate the uncertainties and disturbances in control. By the use of the proposed enhanced super twisting sliding mode control law, the remaining phenomenon of chattering in the last two joints of the manipulator is completely eliminated as shown in our simulation.
In the approach, a radial basis function neural network is employed to deal with
unknown bounded disturbances and uncertainties. Besides, the controller also has its own output filters and constraints for the output signals for stabilizing those signals before sending to the actuators. In addition, the proposed controller also guarantees the stability of the closed loop system, successfully overcomes the chattering problem, and improves the robustness of the control system. Simulations are conducted to verify the proposed controller performance.
Moreover, the effectiveness of the proposed controlled is also evaluated by
comparing with other existing controllers. From the simulation, it is evident that the proposed controller yields elegant features of sliding mode control including fast response, robustness, and chattering-free control.
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