Adaptive sliding mode control of regenerative chatter and stability improvement in boring manufacturing process with model uncertainties

Abstract

In the machining processes, vibration suppression is crucial in order to achieve the high precision as well as high-quality surface and increase of the material removal rate. In this paper, an adaptive sliding mode control approach is presented to supress the chattering phenomenon in the boring process in the presence of model uncertainties and unmodeled dynamics. The boring bar is modeled as a cantilever Euler–Bernoulli beam, which is actuated by a piezo-actuator located at the bar's end. As a more realistic model, the cutting tool is modeled as an added mass at the bar's end. In order to derive the equations of motion, mode summation method with inclusion the first three modes of vibration is applied. After formulation of the problem, an adaptive sliding mode control scheme is used and an effective control law is derived, which eliminates the chatter vibration. Moreover, a full state observer is designed to estimate three dominant modes of the boring bar. The simulation results demonstrate the effectiveness of the proposed control strategy against the model uncertainties and unmodeled dynamics. Also, it is observed that adaptive sliding mode control acts effectively in improving the stability lobes diagram. Consequently, after implementation of adaptive sliding mode control, more material removal rate can be obtained without stability loss.