Precise position synchronous control of multi-axis servo system

This paper describes a precise position synchronous control of multi-axis rotating system. The control strategies to achieve precise servo system are summarized in two main points: an acceleration control is adopted in an inner loop to ensure robustness of speed of each axis against disturbances, and then a maximum error comparison method has been introduced to minimize not only position synchronous errors but also speed errors of all motor axes. At first, the system dynamics including dc motor drive are rigorously presented by using motor circuit equations and Newton’s formulation. Next, the acceleration and speed controllers are readily designed via proportional-integral (PI) control law. Also, to reduce position synchronous errors caused by different motor dynamics, each axis is coupled by the maximum error comparison scheme. The control system presented is investigated through extensive simulations under step- and sinusoidal-type disturbances. Finally, it has been shown that experimental results successfully demonstrate the effectiveness of the proposed control system for four-axis position synchronous control.