Research On Codeless Angle Sensor Using Virtual Circle Feature Recognition

High-precision angle and displacement measurement is an important guarantee factor in the field of modern precision machining and measurement.Rotary encoder plays an irreplaceable role in many fields such as radar,photoelectric theodolite,small robots,3D printer,drones,aerospace systems,and high-precision closed-loop speed regulation systems.With the rapid development of robots,3D printer,the rapid development of modern emerging industries,such as man-machines,requires high-precision,miniaturized angle and displacement measurement devices.With the rapid development of machine vision,the introduction of machine vision technology is used to the field of encoders can greatly improve the accuracy of angle and displacement measurement devices.Based on machine vision,we keep the light source and the photographing system at a super close distance.Using the virtual circle feature track route of the light source rotating with the measured axis,after image processing and later angle measurement algorithm,we develop a high-precision angle measurement device without code disk and realize the miniaturization of the device.Firstly,the coderless angle sensor that using spot disk replaces the traditional encoder's code disc,the spot disk and light source are installed on the rotation axis,and the image sensor keeps a millimeter distance from the light source,and the light spot image transmitted by the light source through the spot disc is obtained.we found that it will not cause defocusing phenomenon when the image sensor and spot disc maintain a millimeter distance.Secondly,according to the characteristics of the light spot image,the image processing technology is used to extract the spot center,and the spot center is regarded as the center of the light source.A virtual circle feature track of ellipse or circle was made by the spot center when the light source rotates with the measured axis,and the least squares ellipse fitting method is used to obtain the rotation trajectory equation.Thirdly,The center of the trajectory is regarded as the center of rotation center,and the rotary angle will be calculated by thecenter of the spot at different position.Finally,Experiments show that the accuracy of the codeless angle sensor can be within-0.23710??0.18783?,and the highest resolution is 0.4326?.and compared with traditional rotary encoder,the codeless angle sensor is more miniaturized.