Wide Range Coordinate Measurement Method under Small Field of View

There is a conflict between wider range and higher resolution in the target imaging method. The new coordinate measurement method of coding target imaging under small field of view is introduced. The local information of the coding target is obtained by visual measurement, then the position information of the target endpoint is acquired by holographic property of coding target, and then coordinate measurement of relatively wider range is achieved. The coding target is designed, coding by infrared spot. The coding target can be correctly decoded if the field of view is greater than 3 code distances. The system measurement model is established, then the relationship between main parameters and measuring accuracy is analyzed on simulation, and then the optimized measurement system is built. Fixed point measurement and distance measurement experiment and data prove that high precision coordinate measurement can be achieved through acquiring the local information of the coding target. The simulation and experiment prove that the method with coding target significantly outperforms a method with normal target. With the coding target method, the high precision measurement in a relatively wider range is realized under small field of view, and light spot of the range as wide as possible is utilized into calculation for improving precision. The measurement resolution would not lose when the measurement range is extended by taking advantage of the holographic property of coding target. The contradiction between wider scope and higher resolution in visual measurement is solved. A new idea for visual coordinate measurements is provided. As a result, this method is valued to be further studied and taken into practice.