High Precision Encoder Data Subdivision System Based On Feedback System

Modern precision instruments and equipment requires faster and faster processingspeed of encoder, so as the computing accuracy. Operation time of common hardwareplatform and segmentation algorithm is long, and the precision is hardly to meet therequirements. In order to improve the encoder signal processing speed and accuracy,we can make it from two aspects: hardware and software. On the hardware side, weuse TMS320F28335DSP chip and AD7656AD converter. Compared with thegeneral DSP chip,28335contains a floating point arithmetic unit(FPU). FPU isspecialized in floating-point calculate, it can increase arithmetic speed greatly.AD7656’s output data has16-bit accuracy, higher than general AD, such as14-bit or12-bit, providing high precision data for subdivision. On the software side, we adoptan algorithm based on closed loop feedback system. Input of this system is the ADsampling values(§￠，￡§), output is measuring angle, which corresponding to thesine cosine values.if the feedback system is reasonably designed, the system outputwill get very close to the theoretical value in a enough short time.Based on the above design thought, we designed an encoder data subdivisionsystem based on closed-loop feedback algorithm and Completed the system hardwarePCB design. And next, we designed the structure of feedback system and algorithmprogram, testing it on DSP for many times to determine the best parameter.Test results show that data processing can be finished in1.5us, having a veryhigh speed. Result precision is0.00628rad at normal noise level, corresponding to the precision of1024subdivision. Speed measure range is up to6000rpm, having goodapplicability.