Novel control algorithm design for A-axis of high-power five-axis machine tools

According to the influence of backlash and nonlinear friction on the control precision of the A-axis, the fuzzy controller (FC) with gain auto-tuning was proposed. Mutation of the control law caused by the gain switching in the traditional fuzzy control was eliminated by introducing the gain auto-tuning strategy based on the continuous exponential function. Although the FC with gain auto-tuning can achieve good dynamic response and smaller steady state error, it needs the two dimensional fuzzy control rules table to calculate the control law. To a certain extent, this control algorithm limits the dynamic response speed of the control system. Therefore, the fuzzy sliding mode controller (FSMC) with gain auto-tuning was proposed, and the chattering phenomenon in the traditional FSMC was eliminated by employing the FC to approximate the nonlinear function item in the equivalent control law. Experimental results show that both control algorithms can achieve higher steady state precision and faster dynamic response with zero overshoot. They can also improve blisk machining precision and surface consistency, and significantly reduce surface roughness.