SYSTEM SENSITIVITY IN OPEN LOOP STEP MOTOR SYSTEMS

摘要

A step motor and associated driver circuit and controller are often used to drive a mechanical load through a prescribed trajectory. During the system design, consideration is given to the trajectory and load parameters, and the characteristics of the drive system. If enough mechanical power is available from the drive system, the use of powerful step sequence generation algorithms allows almost any design to drive the load through the trajectory under nominal conditions. The quality of the design may then be judged by the sensitivity of the load response to variations in important system component parameters. These include the available pullout torque, the load parameter values and initial system conditions. In this study we evaluate the effects of multiple design choices, such as the pullout torque characteristics, controller resolution and trajectory parameters on the resulting system sensitivities to operating parameter variations. The results of such an evaluation may point the way to possible cost reduction, improved performance or both. A modified control algorithm is shown to reduce the system sensitivity to variations in initial position and Coulomb friction.