Research And Implementation Of DSP-based Motion Controller

Motion control is very important during the construction and operation of the beamlines inthe synchrotron facilities. It provides key technical support to ensure the implementation ofvarious experiment methodologies. To get adequate synchrotron X-rays with proper energy、flux、spot size and position at the endstations, the monochromator、slits and mirrors etc. must beadjusted accordingly with the motion control system. The equipments along the beam in theoptical hutch are diverse, and the requirements for the control system are either different. So thereare several motion controllers such as the8-axis MAXv-8000for step motors、the PI-C863forservo motors and PI-E621for Piezo motors. This makes the whole system complicated and bringsinconvenient in developing and maintainence of the software and hardware. So it is necessary todevelop a multifunctional motion controller so as to simplify and unify the architecture of thehardware and software of the motion control system.The technical scheme of one kind of stepper motor controller was studied and developed afterinvestigations of the architecture of the control system and surveys of the requirements of thebeamline scientists at SSRF. It is based on the SEED-DEC138developing board which has theCPU of OMAP-L138with dual cores of DSP and ARM. The low-level dirvers for the hardware、the interrupt subroutines and the up-level main program are developed with the CSS(CodeComposer Studio). The basic motion function、velocity curve and the limit switch protectionfunctions are achieved separately. Three coordinate systemsrespectively for the hardware、engineering and scientific users are designed and they are converted into each other automaticallyin the software. The operator interface was developed using the VC++6.0. Through the interface,users can preset parameters of the motors、set the desired positions、monitor the current states andperform the homing functions and so on. A hardware interface board was designed to connect thecontroller and the driver. A setup for testing was built with the4-blade white beam slit in thelaboratory. The test result shows that the controller is good enough for the requirements of thebeamline control.This thesis achieved the stepper motion part of the controller based on SEED-DEC138developing board. It should be extended to achieve the servo control function and the positionencoder read back function in the future. Additionally embedded linux system with EPICSenvironment also should be developed using the ARM core in the OMAP-L138. Finally,deploying this system to replace the various controllers at SSRF will greatly unify the hardwareand software architecture and reduce the cost.