Design and Experimental Verification of Adaptive Sliding Mode Control for Precision Motion and Energy Saving in Feed Drive Systems

Energy consumption of computer numerical controlled (CNC) machines is one of the critical issues in the industrial community owing to the round-the-clock operation of these machines. Recently, there is a great demand for reducing energy consumption in various industries due to production costs and environmental factors such as global warming and climate change. For this reason, many researchers are focusing on reducing the energy consumption of industrial machines. In previous studies, feedback controllers with fixed gains have been designed to feed a drive system, whereby high control gains are set to enhance tracking performance. Contrarily, high control gains cause high consumption of energy, and this property was less concerned in the previous studies. By allowing adaptation of the control gains so that they change according to disturbance variations, energy consumption may be reduced. This paper focuses on energy saving in feed drive systems by using adaptive sliding mode control with a nonlinear sliding surface. Stability of the proposed control system is proved based on the Lyapunov stability theory, and the convergence of the system trajectory to the sliding surface is guaranteed. The effectiveness of the proposed method has been confirmed by simulation and experiment. The experimental results for a certain trajectory verified that the proposed controller could reduce the consumed energy by 3.4% on average and enhance the tracking performance by reducing the maximum tracking error by 45% on average. In addition to that, the control input variance could be reduced by 12.6%.