Design Of Motion Controller And Research Of B-Spline Curve Fitting

As the core component of numerical controlled machine, motion controller is widely usedin CNC equipment, robot controlling, Detection control automation and other areas. With thedevelopment of micro-electronics and Digital Signal Processor, DSP and field programmablegate array(FPGA) are the important trend in current technological development of embeddedmotion controller. So research on motion controller based on DSP and FPGA is beneficial tohigh speed and high precision of the realization of the NC machining, it also improvesnumerical control system technology in our country.Firstly, the paper compares the various design schemes of motion controller at home andabroad., on that basis, multi-axis embedded motion controller based on DSP6713andFPGA-A3P400is designed and developed. The hardware design is discussed in detail, such asthe DSP and FPGA minimal system, the peripheral circuits of the DSP and FPGA, Powercircuit, the digital pulse output circuits, the encoder input circuits, the interface circuits ofgeneral purpose I/O, the electric level converting circuit of RS-485serial communication andso on.In order to enhance the integration and the reliability of CNC, by programming to FPGA,address decoding signal line modules, pulse generator, the encoder signal processing andserial communication are designed. The design of Serial communication and its submoduleare provided in details. Simulation and testing results show that the design of this system isrational, practical and stable.The research status of the common interpolation algorithm and its characteristic are donedetailed analysis. In order to overcome the frequent acceleration and deceleration, lowmachining federate and discontinuous machining path in the consecutive micro-segmentmachining process, An algorithm of B-spline curve fitting based on the least square method isproposed to approximate the consecutive micro lines into B-spline curve. By analyzing thegeometric characteristics of the consecutive lines, the bi-chord error constraint is presented topick out the appropriate points and keep the deviation between the fitted curve and theoriginal path within the required range. Simulation results verify the algorithm approximatethe consecutive micro lines into B-spline curve without sacrificing precision.Finally, based on mentioned hardware platform and control algorithm, some of softwareof motion controller, including the program of communication between DSP and HMI, testprogram of DSP and program of algorithm of B-Spline curve fitting, are developed with modularization method, DSP/BIOS system and C language. Associated tests of hardware andsoftware of CNC are accomplished at last.