To satisfy the requirement of real-time in photoelectric theodolite and guarantee tracing precision and reliability

a new servo-control system according to MIMD (multiple instruction multiple data stream) structure was proposed. Kallman filtering was adopted to implement data fusion of multi misdistances. Operation principle of theodolite was simply introduced. Mathematic derivation of data fusion in a theodolite with multi imaging systems was given. It showed that solution of data fusion needed large quantity of numerical calculations. To satisfy the calculation requirement and real-time processing demand

a special parallel calculation system with three arithmetic units which was composed of two DSPs and single FPGA. Chaining mode of three arithmetic units was described and time outgoing of real-time calculation for each one was analysis. Hardware simulation was carried out on the special calculation system. The simulation result showed that the system can satisfy the real-time requirement with 1.25ms in theodolite with three imaging systems

while the CCD sampling frequency was 50 Hz and sampling frequency of photoelectric encoder was 800 Hz.