High-precision Position Detection Of Servo System

Servo system needs real-time detection of rotor position and speed to control motorspeed、torque and position. In general, servo system often uses incremental optical encoderand resolver as its position detection device. With the emergence of high-quality servosystem, the accuracy of servo system position detection have become increasinglydemanding.Cosine optical encoder provides the hardware foundation for the high-precisiondetection of the motor. By breaking down the original encoder signal can achieve the motorposition detection precision. At present,widely used subdividing technology at home andabroad have been developed, such as, Resistance Chain Subdivision, Four TimesSubdivision, Carrier Wave Modulation Subdivision and Amplitude SegmentationSubdivision, Phase Locking and Multiple-Frequency Subdivision. These methods haveadvantages and disadvantages,but it is difficult to meet the accuracy requirements inpratice. In this paper, we research a new type of Carrier Wave Modulation Subdivision andAmplitude Segmentation Subdivision. Based on this method, a subdivision circuit is made.In this paper, we use Multisim software to simulate the subdivision hardware circuit.At the same time, we use Quartus II software to simulate the subdivision software circuit.Simulation results verify the feasibility of the method.In this paper, based on this new subdivision, we produce a subdivision circuit board.We make a detailed analysis for every hardware module and test the output signal of eachmodule with the oscilloscope. The reaults meet the design requirement. The software adoptsmodularization programming design and uses Verilog HDL to program FPGA. Thesoftware is divided into A/D control module and look-up table calculation module. A/Dcontrol module make that the FPGA can communicate with A/D converter chip reliably.Look-up table calculation module realizes the subdivision algorithm.In the experimental stage, we test the output signal of each module with theoscilloscope and analysis the accuracy and error of the subdivision circuit. The error ofcircuit trial platform is determined and the potential reasons which lead to the error arefound out. Consequently, several solutions are put forward.