Design And Implementation Of An Absolute Encoder Zero-point Calibration Instrument

In modern industrial production, servo control system which consists of PMSM and drive component occupies a pivotal position. A high-performance servo control system not only should have a suitable servo control strategy, but also need to be installed a high sensitivity, good dynamic performance, high accuracy, strong anti-jamming capability sensor. Although there are a large variety of encoders, absolute optical encoder has been widely used in industrial system for its advantages of high accuracy, the only position value, free of power down memory. The installed encoders should be calibrated before servo motors are sold to customers. TAMAGAWA absolute encoder is a popular absolute encoder on the market for its advantage of stable performance and high performance-to-price ratio. It has important practical significance to design an operation convenient and high accuracy zero-point calibration instrument for TAMAGAWAabsolute encoder.This article focuses on the design and implementation of TAMAGAWAabsolute encoder zero-point calibration Instrument. By analyzing zero-point calibration process of absolute encoder, a general design scheme of the calibration system is suggested and vector control is selected as control strategy. According to the function division, calibration instrument can be divided into two parts:hardware design and software design. Hardware is mainly composed by digital controller and power driver board. The digital controller uses ARM+FPGA architecture, its main circuit includes a minimum system circuit of ARM and a FPGA-based encoder hardware interface. Power driver board outputs three-phase current to control the motor directly, its main circuit is made up of rectifier and inverter circuits. Software development is based on modularization and finite state machine method. The control chip ARM is used to deal with motor control algorithm, the control of calibration process and system parameter setting. FPGA is used to realize the communication between ARM and TAMAGAWA absolute encoder. A system experimental platform is built to test the performance criteria of hardware and software. The test result shows that the calibration instrument can swiftly and accurately complete the zero-point calibration of TAMAGAWA absolute encoder and achieve the desired objectives.TAMAGAWA absolute encoder zero-point calibration instrument has been put into practical application. It works well and improves the production efficiency greatly.