Session: MESA-14-01 Fractional Derivatives and Their Applications: Applications

Paper Number: 70814

Start Time: August 17, 03:20 PM

70814 - A Fractional Order Control and Correction Strategy for EtherCAT Communication Clock Drift 

    In the field of multi-axis motion control, such as industrial robots, the accuracy of the motion needs to be higher through the synchronization of the clock. Ethernet Control Automation Technology (EtherCAT) applies distributed clock (DC) to realize synchronization among different slaves. Due to the influence of the crystal oscillator manufacturing process and environment, there is still synchronization error between reference clock and non-reference clock. To solve the clock synchronization problem, this paper proposes a clock drift compensation algorithm based on the idea of closed-loop control. By designing integer-order proportion integral (IOPI) and fractional-order proportion integral (FOPI) controllers, the synchronization error between slaves can be minimized effectively. The IOPI and FOPI controllers designed in this paper are used to eliminate the drift error. This method improves the synchronization accuracy without bringing too much computing load. The results show that the proposed FOPI controller can effectively reduce the synchronization error with even better performance over the IOPI controller, especially in the aspect of rapidity and robustness. The errors can be controlled within ±40ns by FOPI controller, and the proposed control strategy has a satisfactory control effect. Through the control algorithm, high accuracy of synchronization is achieved, compared with the traditional drift error compensation method.

    Keywords: Synchronization, EtherCAT, feedback control, PI/FOPI, clock drift.

Presenting Author: Jihao Sun School of Mechanical Science and Engineering, Huazhong University of Science and Technology

Authors:

Jihao Sun Huazhong University of Science and Technology
Pengchong Chen Huazhong University of Science and Technology
Ying Luo Huazhong University of Science and Technology