Variable Ccain Adaptive Control System for Turning

Adaptive control as applied to machine tool systems refers to control of the operating parameters based on measurement of the process characteristics. Even the simplest adaptive control system with feedrate control based on cutting force measurements, is quite complex. The adaptive control loop is of a sampled-data nature with a nonlinear variable gain which depends on the operating parameters themselves. Experiments have shown that an operating computer numerical control/adaptive control system can become unstable due to changes in depth-of-cut or spindle speed. The purpose of the present paper is to demonstrate a new design method for machine tool adaptive control systems. The proposed method is based on simultaneous estimation of process parameters and control of the cutting process. The parameter estimation is based on available measurements of the cutting force. The estimator is used to modify the adaptive control controller gain in real-time in order to achieve an effective and stable system.