| High-response and high-precision decided partially by the position detector are becoming the trend of the development of servo drive system. Photoelectric encoder mostly used in servo drive system can be classified into the incremental photoelectric encoder and absolute photoelectric encoder according to the different structures and principle. This thesis deeply analyses the two type encoders based on the principle and makes comparison between them by application characteristics. The conclusion is that absolute photoelectric encoder is more suitable for high-response, high-precision servo drive system.The basic requirement of high-resolution absolute photoelectric encoder is to realize the communication interface to the encoder which usually is serial transmission and is controlled by the corresponding communication protocol. This thesis analyses the absolute photoelectric encoder communication protocols of TAMAGAWA SEIKE CO. JAPAN, which include hardware, frame structure and timing requirement. Then the choice of design devices FPGA and the Verilog Hardware Description Language are introduced, feasibility analysis of the interface circuit of absolute photoelectric encoder based on FPGA is done. On the basis above, the whole interface circuit is divided into sending module, receiving module, serial control module and other modules following the top-down design theory. Each module is designed by Verilog HDL. The designed interface circuit based on FPGA is implemented on the corresponding hardware platform. Finally, every function of the design is verified on the TMS320F2812 servo control platform. |
