Fuzzy sliding mode control of the a-axis with high torque and high power

For the influence of nonlinear backlash and friction on positioning precision of the A-axis in 5-axis machine tools, the fuzzy controller (FC) with gain auto-tuning and fuzzy sliding mode controller (FSMC) with gains auto-tuning are proposed. For the former, the control law mutation caused by gain switching in traditional fuzzy control is eliminated by introducing the gain auto-tuning based on the continuous exponential function of the error. For the latter, chattering phenomenon in traditional SMC is eliminated by employing the FC to approximate the nonlinear function item in the equivalent control law. Experimental results show that both the two control algorithms can achieve higher steady state precision and faster dynamic response with zero overshoot.