Abstract: According to the inverse relationship between the command acceleration at zero-velocity and transition time from rest to macroscopic motion of a CNC alternating current servo worktable feed system, the pre-sliding regime of friction is distinguished form sliding regime, hence a method of friction compensation is put forward based on the estimated value of the torque value. After command acceleration is given, friction in the worktable feed system is compensated without measurement of velocity with friction torque model based on command torque value. Meanwhile, in consideration of param- eter uncertainty, nonlinear friction adaptive control scheme is designed and its stability is theoretically proven. Experimental study verifies the effectiveness of the adaptive compensation scheme based on the estimated value of the friction torque value. and shows that this adaptive compensation method based on presliding-dynamic friction torque estimation model can implement tracking of expected locus at different command acceleration and greatly improve the tracking precision of the system.

Key words: Alternating current servo worktable, Feed systems, Feedforward compensation, Friction model