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| s a time-dependent, nonlinear and complex phenomenon, friction has a complicated influence on servo current and output signals of the AC servo controlled x-y work-table system, such as displacement, velocity and acceleration. Since it is much more difficult to measure frictional force (or torque) directly, the servo current was employed to indirectly reflect dynamic changes of friction. Firstly by means of wavelet multi-resolution analysis, information feature from static friction to dynamic friction was extracted from servo current. The time relationships of this feature, displacement curve of the worktable and command acceleration were derived, which shows that there exists an interval, named as transition time, between the instant the linear grating sends out pulse and the instant sudden change happens in servo current. Subsequently theoretical analysis derives a relationship between transition time and acceleration at zero velocity, that is, the transition time is proportional to |
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| Keywords:Friction; AC servo feed system; Servo current; Acceleration; Transition time |
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