The Study Of Multi-Point Forming Control System Based On Parallel Mode

Multi-Point Forming (MPF) is a flexible manufacturing technology forthree-dimensional sheet metal parts, which utilizes a matrix of adjustable discreteelements group to replace conventional die. The displacement and velocity of eachelement can be controlled by computer, so the contour surface the elements groupcan be changed accordingly. Compared to the conventional die, MPF technologyhas found extensive application fields because of its flexibility. Multi-Point Forming control system is an important part of Multi-pointforming equipment. Parallel adjusting is a rapid shape adjusting mode with thisfashion. Each element is controlled independently by microcomputer, and theyreach the desired heights. So the shape adjusting efficiency of the MPF equipmentis improved remarkably. Throughout the thesis the issues concening the design and fabrication of aparallel mode MPF computer-controlled system for sheet metal parts has beendiscussed. The computer control system is a computer distribution control systemwith RS-485 bus. The main contents of the thesis are as follows: 1.Single control unit has been designed and fabricated. It consists ofcommunication interface circuit, clock circuit, watch dog circuit, light-electricitycoupling circuit, drive circuit, and feedback circuit. It fulfils the function ofcommunicating, collecting data, dealing with data, and controlling the height ofsingle element. 2. Communication message package which satisfies requirements of thecontrol system has been defined. The message package consists of startup frame,address frame, data frame, end frame. It includes all information which theindustrial PC and slave microcontrollers require. Odd-even test has been realized incommunication. The issues concerning RS-485 bus have been discussed in thepaper. The dependability of communication has been analyzed 3. The master computer software is programmed in VC++6.0. It is a kind ofmonitoring software which can set up the parameter, adjust elements to the same 64Abstractheight, adjust elements to various shapes, analyze the results, and control powersupply. It receives the data file from MPF CAD software, deals with data, sets upcontrol mode and equipment parameters, sends data and command to the slavecoputers by RS-485 bus, controls the elements group to shape different contoursurface, and controls press to form parts. In the course of shape-adjusting, themaster computer inspect the status of the slave control unit. If the status is right, themaster computer continues to communicate with the slave computers, and wait foranother command. If the position error exceeds the requirement, new data file willbe created, and the control system continues to adjust elements to the desiredheights. If the status is wrong, the control system will stop, and give an alarm. Themonitoring software has been proved effective in practice. 4. The slave computer software is programmed in assembly language. Whichis used to receive the data and commands from the master computer, sends thestatus and parameters of the slave computer to the master computer, and control theelement to desired height. In the paper, single neuron adaptive PID positioncontroller for brushless DC motor has been proposed. 5. Safety and dependability of the control system have been studied in thepaper. Measures have been taken for the hardware and the software. Thesemeasures have been proved effective in practice. 6. The position control experiments have been done and the reason of positionerror has been analyzed. Single neuron adaptive PID position controller forbrushless DC motor satisfy the requirement of the system. The control systembased on parallel mode has been applied to MPF equipment in practice. Theresult indicated that the system is effective and efficient.