Design Of Multi-motor Distributed Control System For Optical Fibers Positioning Based On CAN Bus

In fiber spectroscopic telescopes,real-time precise position measurement of the optical fibers is the key to track the stellar objects.The LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope)is a reflex Schmidt telescope.The most important part of it is a diameter of 1.75 m coke panel on which 4000 opticl fibers nodes has been installed.In order to confirm the position,the focal panel has been equipped 4000 optical fibers nodes.Each of them control the position of the fiber accurately.The key point of the telescope is how to connect these nodes and drive the stepping motors.As a kind of reliable industrial field bus,CAN bus has high reliability,strong real-time performance and flexible use occasions.Therefor,we choose CAN bus to build a communication networks for fiber positioning systems.In the LAMOST fiber-optic positioning system,each node drivers two stepping motors for rotating the fiber optic.And the node communicates with others by ZigBee technology.Due to the limitations of the wireless communication technology,this design finally selected a variety of distributed control system with CAN bus communication networks which has the capable of driving the stepping motors.Each MCU of the CAN bus nodes integrated with the CAN controller makes the achievement of simplifying the design of the hardware circuit.MCU controls the subdivided driving chip to subdivide the stepping motor.The main function of the CAN bus node has been given and the software design of the node has been completed.When completed the hardware and software designs,we tested the CAN bus communication function and driving ability of motors by making several nodes to build the CAN bus communication network model.The result of the test illustrated that the CAN bus network can normally carry out the communication between nodes and drive the motors in 1/16 subdividing model.The whole system run well and make a good real-time performance which meets the requirements of fiber optical positioning system.