The ideal motor for precision machines is one that produces a controlled force in a single direction with negligible heat generation. Practical motors generate off-axis forces that interact with the finite stiffness of bearings and servo systems to generate error motions. Error motions in the direction of travel lead to a velocity ripple, and errors orthogonal to them are the geometric error motions. In spindles these are radial, axial, and tilt error. In linear slides, these can be straightness, pitch, roll, and yaw. Current-carrying wires that generate force also generate heat, and this heat will lead to thermal deformations and loss of accuracy if not properly handled in a system. The purpose of this paper is to present a tutorial of commonly available motorization options for precision motion control systems. It begins with a review of motor fundamentals, shows examples of the motors being applied in practice, and provides suggestions for reducing the unwanted influences of parasitic forces on the axis motion. In general, the design of linear and rotary systems is identical. Specific differences will be noted where they appear.
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