Abstract
For a larger depth of cutting above a certain critical value, self-excited vibrations occur in case of milling operations. This phenomenon of unstable milling tool vibrations is called chatter and is the main cause of the workpiece surface finish deterioration. The working life of the milling tool decreases substantially if the chatter is ignored. Active chatter control technique using the fractional order control methodology is investigated in the present work. Controller parameters are optimized by using the pattern search optimization technique. Electromagnetic actuators are used to generate the required control forces. The proposed technique is compared with the optimal loop shaping (LS) robust controller and optimal traditional proportional-derivative controller. It has been observed that the chatter can be avoided with relatively much less amplitude of control forces using the proposed controller. This aspect not only reduces the size of the required actuators but substantially reduces the control energy required to maintain stability. With the proposed controller, there is 168% saving in the control energy compared with the widely used robust control strategy. The robustness properties of the proposed controller are comparable with the loop shaping robust controller. Experimental results verify the efficiency and robustness of the proposed method.
