Abstract: In the traditional optical angular displacement measurement method,there are some problems such as complex optical path and weak anti-interference ability. Therefore,a novel angular displacement measurement method based on optical coding imaging is proposed. Firstly,the method uses the principle of converting gray code into binary for reference,evenly distributes two circles of RGB (Red,Green,Blue) blocks on the circular surface with a diameter of 50 mm,and converts the color information around the outer circle target point into binary number corresponding to the absolute position by detecting the color information. Then,in order to reduce the noise,Gaussian filtering and median filtering are used to preprocess the image,and the Hough circle algorithm is used to locate and track the target point to obtain its starting and ending positions,so as to calculate the coarse angle. Finally,the coarse angle is compensated by the angle between the position of the target point in the last frame of the video and the final position to achieve angle measurement. By building the experimental platform and making the sensor,the accuracy measurement and stability experiment of the experimental device are carried out in the 360° measurement range. The resolution is 16 bits,the measured mean square deviation is 0.23°.The new angular displacement measurement method proposed brings new ideas for the field of angular displacement measurement.

Key words: angular displacement measurement, optical encoder, RGB blocks, sensor