| The table control and detecting system for Nuclear Magnetic Resonance Imaging equipment is developed in this project. And the control object is the table of Ovation 5 Nuclear Magnetic Resonance Imaging equipment in GE Healthcare Group. In the thesis, the design requirements and the functions are analyzed in detail, and the design of the system, including hardware design and software design, is expatiated clearly.The control object of the system is the table of Nuclear Magnetic Resonance Imaging equipment, and the purpose of the system is to realize the motion control and detecting function for the table transverse movement and lengthways movement. The lengthways motion is driven by a DC servo motor, and the transverse motion is driven by a DC step motor. The table control has two control modes: including local hand control and host long-distance control. The control system is mainly composed of control unit, executing part, detecting unit and display unit. A key controller is designed with AVR series MCU and MAXâ…¡series CPLD. The DC servo motor is controlled in the PWM way. A PI adjuster is applied in the system, and it has very good dynamic and static performance. The DC step motor is controlled by a driver in the open-loop control way.To lower the interference between different voltage levels in the system, the control part and the power part are displaced on different boards. The system hardware includes main control board, display and button board, and motor driver board. Main control board is the key part, including MCU and CPLD, table position signal digital filter circuit, voltage conversion circuit, serial communication circuit, current signal conversion circuit and the periphery circuit. The display and button board is the man-machine conversation part. The operator uses the buttons and switches to realize the system control and detecting function. Motor driver board is connected directly with the two motors, including DC servo motor driver circuit, DC step motor driver circuit and over-current protection circuit.The software design of the system including two parts: the MCU firmware and the CPLD firmware. The AVR MCU firmware is designed in ICC language. And modularize design is used to enhance the readability and facility of transplant. The main modules include the main program, buttons scanning, dynamic display, PWM control, transverse motion detecting, lengthways motion detecting and lifetime test module. The... |
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