Cross Coupling Controller for Accurate Motion Synchronization of Dual Servo Systems

Abstract

In order to attain higher manufacturing efficiency, “dual” (two) servo systems are widely used in advanced Computer Numerical Controlled (CNC) machine tools. A well-known example is the linear motor driven gantry type of micro machine tools where dual servos are employed to drive the heavier gantry axis. Recently, dual servos are also used in spindle systems. “Double sided milling” is an example where two spindles are required to cooperatively remove material on both sides of a workpiece. Synchronization of dual servo systems is crucial for achieving the desired manufacturing accuracy. This paper presents a crosscoupling controller to accurately synchronize dualmotor driven servo systems. Proposed cross coupling controller penalizes differential positioning error between dual servo drives by modifying the reference position and velocity commands. It improves motion synchronization without affecting the overall tracking bandwidth. A tuning method for the proposed controller is also presented for the control engineer’s practice.

Position - Velocity Control for Two PMDC Motors Connected by a Cross-Coupling Technique with Butterflies Optimization Algorithm

“…Burak Sencer and Eiji Shamoto in 2014 Introduced a control system used to operate a gantry-type machine tool. It consists of two controllers for each PMDC motor, a PI controller for speed P controller for the position [17] . In 2017 Nishant Kumar and Tiwari presented a speed control system with a cross-coupling technique used to synchronizing movement for several DC motors.…”

Accurate physical modeling and synchronization control of dual-linear-motor-driven gantry with dynamic load

“…Part of the reasons might be due to the absence of an accurate dynamical model, leading the uncomplete knowledge of the system. Commonly, the motion of each motor is modeled individually [7][8][9], while the mechanical coupling between •3• two parallel motors is essentially ignored, which makes the resulting model actually have no guidance meaning on controller development. Other researches on the coupling effects can mainly be concluded into two categories.…”

“…Limited by the aforementioned situation of modeling, earlier synchronized control schemes are usually based on the pure motion synchronization, e.g., the synchronized master command approach [17][18], the master-slave control [7][8], and the well-known cross-coupled control [8][9], [19]- [21]. Due to the ignorance of the mechanical coupling in dual-driven systems and the following internal forces issue, the achievable synchronization performance is actually limited, which has been detailedly examined in [14].…”

Cross-coupling control method for five-axis computer numerical control machine with dual rotary tables

“…The research results show that the cross-coupling controller is a more effective way to improve the contour accuracy compared with the advanced single-axis servo controller. [2][3][4] The key technology to realize crosscoupling control is to establish real-time contour error calculation model and contour error compensation amount calculation method. [5][6] Yeh and Hsu 7 transformed the cross-coupling controller to the equivalent single-input single-output system with the introduced contour error transfer function and defined the distance from the actual cutter position to the tangent through the instruction position on the reference curve as contour error approximately.…”