Signal Pair Pole Magnetic Encoder Based On DSP

The magnetic encoder is widely used for measuring the rotating angle and rotating velocity of servo motor system. By using the non-contact property of magnetic field, the magnetic encoder can change the position and rotating velocity information of rotating object into electrical signal. Compared with the optical encoder, it has the advantages of small size, simple structure, fast response, less susceptible to water vapor dust and the disadvantages are low resolution and precision accuracy which limits its development and application.At the signal receiving section, this article using the new-type magnet structure and the hall element to design the magnetic encoder signal generation section and limit the signal voltage into0-3V then input it into A/D module by level shifting circuit. Use the high-performance processor TMS320F2812provided by TI’s to make the signal processing design. TMS320F2812has2-way8-channel12-bit A/D converter (fastest conversion time of80ns),2path SCI module. It can simplify the circuit design process. Since manufacturing and environmental factors will both effect the calculation of the angular position, this article analyzes the sources of error and the effective of error, proposes the elliptic-based error compensation method and uses a combination of calculation and interpolation calibration look-up table as the signal process method to double the system resolution. After the processing of DSP, the signal has been sent to the microcontroller through the serial port, the89c52single-chip and LED digital tube are used in the display circuit design to achieve the real-time display of measurement signal with the accuracy of0.1degree. In order to verify the accuracy of the magnetic encoder, the circuit of optical encoder combined with the phase discriminator and display circuit is designed. Accuracy of the magnetic encoder can be verified intuitively and effectively with optical encoder.