Coupling Motion Systems for Zero Backlash

Selecting mechanical couplings for machinevision and optical-inspection systems requires a trade-off between damping and rigidity. Machine-vision and optical-inspection systems demand precise motion control, and this requires precision components. One often overlooked but important component is the zerobacklash coupling that connects a motor to a linear stage. For instance, a coupling might connect a servomotor to a ball screw that drives a vision system used for inspection. • Mechanical couplings used in precision motion systems require a trade-off between damping and rigidity. • Different servocoupling designs offer varying speed and misalignment capabilities. See more on the basics of servocouplings in the Video Library of Such couplings must have zero backlash to ensure accuracy and repeatability. In other words, there can be no play between components. If the motor shaft turns 90°, a zero-backlash coupling guarantees the ball screw shaft turns the same 90°. Vision and inspection systems usually operate in one of two general modes. One is the stop-and-image motion system that moves quickly to one spot, takes a picture, and then moves on to capture another image. Rapid starts and stops inherently cause vibration in this type of system. Couplings that dampen these vibrations reduce settling times and increase through-put. The second type of system operates in a constant scanning mode. Unlike the stopand- go approach,