Design Of L Type Wave Maker Motion Control System Based On EtherCAT

In the field of ocean engineering, the L type wave maker is the array device often used to simulate large scale waves in the lab for providing scientific experimental conditions for the study of wave and the research of wave motion impact on structures. This is of great importance to enhancing design theory of marine engineering and improving construction technical level of marine structures.Working theory and key design technologies of wave maker are introduced in this paper. The technology of Baumueller motion control and EtherCAT are studied and a synchronous motion control solution with multistage master-slave structure is proposed and it is successfully applied to 156 axis high-power L type wave maker to realize synchronous control of all wave units strictly. Design MFC program on Windows platform as PC control software, adopt Baumueller Controller PLC02 as the field motion controller and complete system configuration and motion program in its integrated development sotware, ProMaster. Through socket communications all control devices achieve the access to each other in the way of TCP. For problems of large amount of data and low transmission speed between IPC and motion controllers, a lossless data compression is used to cut down generated wave data size, and a multi-threaded Ethernet communication method is adopted to increase transmission speed. For the limited performance of motion controller, a fast and efficient cubic spline interpolation algorithm is applied to realize online trajectory planning. Moreover, for large mechanical inertia and load of the system, overcurrent phenomenon of motors may happen during its starting and stopping process. Therefore, a cosine fitting algorithm is proposed to optimize it. In experiments, the system went stably with high data transmission speed and precise synchronous performance, which can fully meet requirements of large scale ocean wave simulation.The successful application of synchronous motion control technology with multistage master-slave structure in wave maker provides support to develop larger L type wave maker and also help to the design of complex synchronous motion control solutions in other fields.