A PID controller design to suppress chatter vibrations in the turning process & studying its effect in nonlinear delayed process

Abstract

High-quality, high-production-rate machining operations are significantly hindered by the regenerative chatter. Therefore, chatter suppression is of great significance; and active control is one of the best ways to curb it. In this paper, the orthogonal turning process is modeled as a single-degree-of-freedom system that includes the effect of tool wear; and described through a delay differential equation (DDE). Based on the model, stability lobes diagrams are obtained by the trial and error. The actuator force is the input for the control system and the tool vibration is the output. A classical PID controller is designed to improve the stability of the process and curb the self-excited vibrations. The controller is then tuned in order to achieve the vibration's suppression, short settling time, low overshoot and small actuator force. Based on the stability lobes diagram, the presented controller increases the limit of stability and attenuates the chatter in turning process. Although the effect of the controller on a system's vibration depends on the actuator's saturation force, using an actuator with a relatively low saturation force leads to a satisfactory performance. An electronic circuit for the force actuator that implements the proposed controller is a future phase of the current research.