Research And Implementation Of Distributed Motion Control System Based On Ethernet

The motion control is an important branch of auto control area. With the development of industrial field bus control system, network turns into an inevitable trend of the motion control system development. Using the industry Ethernet to construct the distributed motion control system network becomes a hotspot of the motion control system research. In order to solve the network delay and synchronization problem in motion control network, methods of changing Ethernet physical structure or communication scheduling have been used to improve the network. These methods make it possible of Ethernet using in real-time application, however, they sacrifice the universality of Ethernet.In allusion to the network delay and synchronization problem in motion control network, the method of combining the network time synchronization and timer trigging is advanced to implement the synchronizing control of multi-axis motors. Time trigging is a method to set the executing time in control commands and forth controllers execute commands at the same time. In allusion to problems of the large amount of interpolation commands in network and small memory in controllers, network flow control method base on sliding window protocol is brought forward to assure the interpolation commands been transmitted in real time.The motion controller and servo controller, based on the programmable Ethernet controller hardware platform, have been implemented by software programming, and distributed motion control system has been buildup with switch Ethernet. Crystal oscillator bias between controllers has been analyzed. Network time synchronization has been realized, as while as timer trigging mechanism has been implemented with the help of timer provided in micro-controller. Line interpolation, circular interpolation and electronic gear have been achieved in the foundation of time synchronization and timer trigging. The infection made by rounding error and crystal oscillator bias has been analyzed and timer compensation arithmetic has been implemented to improve the interpolation control precision. The method using cubic spline to approach sine curve has been implemented to fast arithmetic of trigonometric function, and increase the speed of circle interpolation calculating.The four axis synchronizing motion control platform has been buildup. The feasibility of time synchronization and timer trigging mechanism has been confirmed. The line interpolation and circular interpolation function of distributed motion control system has been tested.