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

Reduction of energy consumption is one of the fundamental requirements in industry, in particular computer numerical controlled (CNC) machines. Because these machines operate for a long time and extensively contribute in diverse applications all over the world, reducing even a small percentage of consumed energy can lead to significant energy saving in manufacturing sectors. This paper concerns with improving motion accuracy and energy saving based on adaptive sliding mode control (ASMC) for industrial feed drive machine tool. The proposed control approach is derived based on the Lyapunov stability theory and its control gain is designed to be mainly relied on resultant motion errors of drive axes. Once the tracking error is changed, the control gain is simultaneously adjusted to generate appropriate control signal to provide good tracking performance with reducing energy consumption. Furthermore, the proposed adaptive gain does not alter only during the reaching phase but also through the sliding phase, and hence consumed energy reduction is further expected. In order to verify the effectiveness of the proposed approach, it was compared with non-adaptive and typical adaptive sliding mode control approaches with a circular trajectory of an industrial feed drive system. Experimental results show that the mean and maximum tracking errors of the proposed scenario could be largely reduced by 34.81% and 33.66% on average compared to a constant control gain without any increase of consumed energy, respectively. The proposed approach effectively improved the control input variance by 1.54% and 2.34% compared to constant and typical adaptive gains, respectively. Consequentially, consumed energy was reduced by 2.89% and 1.26% on average.