Development Of Motion Controller And Research Of Motion Control Algorithm Based On DSP

The NC technique is one ?of Advanced Manufacturing Technology(?the computer integration manufacture system and flexible manufacturing system),also it promotes the country machine tool industry and the enhancement manufacturing industry international competitive power foundation, its development condition decides a national manufacturing industry level. While Open CNC system a new technology, it is the development of technology for NC today. Open architecture numerical control system (Open NC) is a trend of the numerical control technology. Motion control technology is a core component of NC and comply with the development trend. So motion controller is applied in Open architecture numerical control system. As one of kernel-parts in PC (personal computer) +NC system, a type of Open NC, motion controller is becoming a research focus. The paper systemic expound the motion control technology of NC system. With the PANASONIC Minas A4 series ac servo for motion control platform and overall schemes are presented and considered ,it is concluded that based on DSP motion controller can satisfy demand at discretion occasion and will be the trend of the numerical control technology. So the motion controller mentioned in this paper applied motion control chip TMS320F2812 of American TI company and based on PCI bus. The hardware and software of motion controller are studied theoretically and experimentally. As for hardware, three overall schemes are presented. Considering the development costs, the hardware architecture model of DSP +PCI is chosen. All units of the motion controller are analyzed and designed one by one. TMS320x28x is the TI Company newest promoted DSP chip and special motion control chip. With this type of motion control DSP chip, development of the digital control system in the control algorithm update and control structure changed has a lot of flexibility and only needs to adjust the control software. Because of DSP calculation speed advantage, adaptive control, fuzzy control and artificial neural network control can be realized in the control system, the quality of control system improve significantly. The high-speed multi-axis interpolation and DSP PID mediation have a very high date transfer rate, PCI bus exactly satisfy the requirement of the hardware. So the hardware design using a PC communication with motion controller through PCI bus, based on TMS320F2812 DSP to achieve interpolation algorithm in motion control system is applied. Hardware design structure of motion controller as Fig1 shows.In motion control system, PC places the data in DMARAM through the PCI bus ,carries on the data communication with DSP; DSP reads out these data to carry on interpolation computation, obtains the theory position; The position feedback function module receive electromotor encoder signal, calculates the theory position and the physical location error; D/A transformation function module exports analog control voltage, linkes to the speed command input connection of the servo electromotor, controls the servo electromotor movement; On the motion controller also has the expansion the input/Output function module, uses for to realize the DSP motion controller to expand the PLC function, realizes in the machine tool to measure I/O control; The decoding circuit may by program the component to be composed, completes the entire controller's decoding. The development of the motion controller function modules includes: DSP system power source, clock electric circuit, memory expansion design, DSP and the PC communication connection way, the DSP DAC output unit, PCI interface design, EMC hardware design etc.In NC motion control system, the key problem is the control algorithm design. Even if there is lots of new control-law today, PID control is still the most widely used. The paper firstly discusses basic PID control algorithm, PID parameter tuning and extensive PID control algorithm. Fuzzy control system is particularly studied on the purpose of overcoming the unfavorable factors as the change the system parameters and nonlinearity etc. The paper describes the basic method of fuzzy control and designs fuzzy control unit and fuzzy-PID control unit with the simulation on MATLAB platform, fuzzy-PID control is proved to be a satisfying effect in the situation of changing system parameters. In the simulated control system, the expression for PID control law is: where K p is proportional gain, Ti the integration time, Td the differential time, u (t) the control volume for output of controller. For DSP system is of sampled-data control, which realizes the discrete control according to the control volume calculated by the discrepancy of sampling hours, and can not progress continuous control by outputting control volume continuously in simulation controller. Therefore the digital PID control algorithm is obtained as follows:Where u ( k ) is the sampling time for computer output.However incremental PID control algorithm has many advantages, such as programming simply, recursive historical data, less memory when using, simple computation and facilitation by computers etc. The actual control amount for time K: Based on PID controller, fuzzy PID controller is improved, whose parameters ( K p,K i,K d) are decided by fuzzy control rules and experience of experts. When the characteristics of the objects are changed, the parameters ( K p, K i, K d) of fuzzy controller have also altered. As a result, the control qualities in a variety of conditions have good indicators to meet the requirements of industrial control. The principle diagram is as follows:Using PID controller and fuzzy reasoning methods, fuzzy PID controller finishes the online self-setting of K p,K i and K d for PID controller according to different e andΔe. The principle structure composed of two parts: the conventional PID control parts and parameter adjustment parts of fuzzy control. The MATLAB simulation results are provided as below: Fig.3 shows step response curves of digital PID control unit. Fig.4 step response curves of fuzzy PID control unit.From above two figures, it is not difficult to see fuzzy PID control is faster and more robust than traditional PID control. The research of this dissertation can be summarized as following several points:(1) After analysis of the NC system based on the development of motion control technology, with the PANASONIC Minas A4 series ac servo for motion control platform, the motor control circuit module and the basic system control software have been finished, the hardware debugging platform was set up. All of these laid the foundation for the development of the entire system.(2) a practical motion controller is developed, and all the hardware debugging is finished. Meanwhile, aiming at the problems of designing and debugging of the whole motion controller, some practical experience during the software and hardware debugging was provided.(3) Conventional PID control strategy of servo control system algorithm was analyzed and fuzzy PID control of combining fuzzy rules and PID control was put forward based on the inadequate of conventional PID control. Though comparison and analysis of the results, fuzzy PID control algorithm can improve static and dynamic characteristics of system.