Modeling and Identification of a Digital Feed Drive

摘要

The machining of no-circular body of revolution requires that feed drive possess not only highrnresponding ability, but also large stiffness. An innovative feed drive actuated by the stepper motor is introducedrnfor the purpose. To eliminate quantitative error, the stepper motor is controlled under the continual mode. It isrnachieved with a micro-controller system and a built-in control algorithm program, called "tracking algorithm".rnIn the way, the motion of the tool frame smoothly tracks the input signal. This paper presents modeling andrnidentification of frequency response of the proposed drive. The stepper motor under constant-current supply isrnindentified as a second order system, because the impedance of the coil is negligible. The natural frquency of thernstepper motor is decided by the static torque and the rotary inertia. In the tacking algorithm, the signalrnconversion is approximated as a first order system, the time constant is dependent on sampling cycle, limitationrnincrement and also the amplitude of the input signal