Photoelectric Tracking Digital Servo Servo Controller Design

Firstly, Development of photoelectricity tracking and measuring system at home andabroad is introduced in this paper, and the significance of this paper is expatiated on. In orderto increase the tracking accuracy of the photoelectric theodolite, more and more complexreal-time algorithm is applied in servo control system, which is a sub-system ofphotoelectricity tracking and measuring system. It means that servo controller is able tocomplete massive operations in shorter time. In other words, the operations set a higherrequest on servo controller. For a long time past, Development thought of photoelectricitytracking and measuring system in home continuously pause in integrated development. Thetechnical routes take system integration as the thread, and PC, industry control board, SSIC asthe base. The actual result showed that this kind of designing manner is highly mature andeffective, but it has many drawbacks. For example, out-of-date technologies, redundantdevelopment, core technologies being under the control of others, low integration, largevolume, complicated interface and so on. So, as the improving standard of range and thedeveloping of semiconductor technology, it is absolute essential to develop a new generationof servo controller, which is all-digital, high precision, wide range of speed control.Based on the actual project requirement, this article designs a digital servo controlsystem based on DSP+FPGA. In the system, DSP(TMS320F28335) is the core processor,receives the position command and control order words from the upper computer, exchangedangle value from photoelectric encoder and miss distance value from PSD with DPRAM inFPGA through8-bit data and address bus, complete double close-loop feedback control(speedloop and current loop). It configures DAC with two channels by SPI bus, and the outputdrives the motor after power amplification. As a coprocessor, FPGA(EP2S30F484C5) is thebridge between internal and external interfaces, samples the azimuth angle and elevationangle feedback from photoelectric encoder, miss distance value from PSD, sensor data of single-rod and gyro. It also achieve synchronization output between internal and external.With the requirements of the tasks, the paper designs a servo controller which is appliedin project, including schematic, PCB and software implementation of every module. Thepaper asocial with the PID control algorithm, which is used quite mature in the field ofphotoelectric tracking system, the main program flow chart, the subprogram flow chart andDSP and FPGA union debugging results have been given. At last the article explored thesystem’s upgrading space.