Design Of Distributed Motion Control System Based On Serial Bus

Motion control is the basis of modern manufacturing.The traditional control device can only connect a fixed number of servo axes,multi-axis expansion is difficult,and wiring is complicated.With the rapid development of network technology,networked motion control system has been more widely used in industrial automation.It can realize the free configuration of the servo axis,but it is difficult to realize high precision time synchronization between network nodes.In order to meet the need for multi-axis coordinated motion of SMT placement machines.This paper designs a distributed motion control system based on serial bus.First,the overall structural planning of the distributed motion control system was completed.Motion controller serves as the master station of the system.Each servo axis serves as a slave node of the network.The master and slave stations are connected in series to form a ring topology.The real-time motion tempo in the system is controlled by the master station.The PC machine based on Windows system is used as the upper-computer operating platform of motion control network,which greatly reduces the real-time requirements for the upper-computer operating system.Second,the synchronization algorithm of the slave node is studied,and a high-precision multi-axis synchronization compensation strategy is proposed.In a cascaded control system,there must be a certain delay in the transmission of data.In order to ensure multi-axis motion synchronization,a synchronous compensation timer is designed inside each servo slave station,and the compensation time of the timer is configured according to the communication delay between the slave stations to realize the multi-axis synchronous function,and through the hardware experiment platform,this compensation strategy has been systematically verified by experiments.Thirdly,the motion control algorithm of the master station is designed,it mainly includes motion control,multi-axis interpolation algorithm,acceleration and deceleration control method and motion trajectory planning.In order to meet the requirements of the slave station,a FPGA-based slave module was designed.The FPGA was software programmed using Verilog HDL language.The function of some modules was tested by using Modelsim software.Finally,the cascaded SPI interface network connection and servo motor motion control were realized.Finally,use a master station and three slave stations to build a distributed motion control experiment platform.Experiments show that the communication between the master and slave stations is normal,the servo motor can operate stably,and the encoder data of each servo motor can be fed back to the master station in real time through the slave station interface.The entire distributed motion control system can operate efficiently and stably,and 25ns synchronization precision can be achieved between each servo slave station.