A Research Of All-digital Photoelectric Angle Position Sensor

As a device for measuring angle using photoelectric technology and mechanical technology, photoeletric angle position sensor convert the angle to optical signal by optical encoder disk, then convert optical signal to electric signal by photoelectric conversion. Afterwards, the axis angle information is measured directly and indirectly. Photoeletric angle position sensor acquires signals of angle segment structure by using AD chip usually. Undoubtedly, this sensor can get high accuracy, however, it will cause zero drift in extremely high and low temperature environment.Realizing photoeletric angle position sensor using all-digital way was researched in this thesis. A new method of digital angle segment was proposed to divide Moire interference fringes digitally, and absolute code fringe of Gray code was used to divide high-order angle. Photodiode array, which was corresponding to code channel of encoder disk, was used as optical detector. The output data of photodiode was binarized by comparator, and then converted to electric signal code.EP2C5Q208C8N of Cyclone II was used as process device in subsequent signal processing part. FPGA program was developed with Quartus II, using top-down design process. Diagram Module was used in the top, and each submodule was generated by Verilog. After connecting submodules, appropriate program should be added to them.LabVIEW was used as PC development software to develop data detecting interface. The data transmission way of slave computer to host computer was UART communication protocol. Real-time angle position data of all-digital angle sensor can be viewed by PC, moreover the history data record can be stored.The innovation of this dissertation is that this all-digital sensing processing method can avoid signal drift, which is generated by temperature, and ensure the accuracy of the photoelectric angle sensor in extreme environment.