Abstract: The servo-lag error is big and hard to be controlled in non-circular grinding owing to the big inertia of grinding carriage and the large acceleration of crankshaft. Therefore, it seems unsatisfactory to enhance the contour precision of crankpin by compensating the servo-lag error of a single axis in non-circular grinding. To obtain a more accurate contour, the cross-coupled control system is designed based on the approximation that the coupled motion between the rotation axis of crankshaft and the linear axis of grinding carriage is simplified as the motion between two linear axes. And then the control strategy that the parameters of cross-coupled control system are variable along the motion path of crankpin non-circular grinding is proposed to make up the deficiency of cross-coupled control in the nonlinear path. Aiming at minimizing the contour error, differential evolution(DE) algorithm is also introduced to optimize the control parameters piecewise. The simulation example with test results demonstrate that the theoretical contour precision of crankpin tracing grinding under the cross-coupled control with variable parameters in comparison with under ordinary proportion integration differentiation control or cross-coupled control.

Key words: Contour error, Crankshaft, Cross-coupled, Differential evolution, Non-circular grinding