The polar coordinates equation of Archimedes spiral is <i>ρ</i> = <i>ρ</i><sub>0</sub> + <i>aθ</i> , also known as uniform speed spiral. In a polar coordinate system, the polar radius <i>ρ</i> has linear relation with polar angle <i>θ</i> . This character could be used for linearity compensation in mechanical engineering, or metrical instrument. For example, it could be used for moment linearity compensation, the common configuration has a pivot axis on the pole, and a thin line wrap around the spiral on the turntable. The gravitation of a suspension used as constant pull, and the level polar radius as force arm, then it generates a liner moment when the Archimedes spiral rotating at uniform speed. But as the polar angle of tangent point on the plumb line changes at any moment, the polar radius on level direction isn’t linear with polar angle anymore, and the small error influences the effect of linearity compensation configuration. This paper presented the application of Archimedes spiral in linearity compensation, analyzed the theory error, and deduced the error equation by Mathematic theory. Using computer emulator, educed the precise errors of some dispersed points in common use, and provided according error tabulation. In engineering applications, engineers could consult this error tabulation and correct the points on Archimedes spiral, to realize accurately linearity compensation.
In this paper, a novel experimental method is proposed in order to verify the availability and reliability in separate system. To measure the position-change caused by the fault-mode machine-separate of the electric isolator plug and to know the real switch process of the important component, the ground separate experiment is required to simulate the real object separate process and to obtain the relative position of isolate component under different separate parameter. In the experiment, a position measurement system based on high speed photograph principle is introduced which has hardware, software and gauging method of photograph measure system. A in-situ measurement system is set up by two high speed camera in order to synchronized image collection of separate process. After extracting, matching, coordinate and position calculating to the image, a relative position of the isolator component at the time of separate process can be deduced. The relative separate speed at this time can be calculated by the position parameter. The measurement system can be tested by the three-axis standard revolving stage. The results of the measurement experiment show that camera response frequency is 1000Hz, the relative error of position measurement is less than 5%, the relative error of speed measurement is less than 5% which can meet demands of experiment.
Positioning error of robot is a main factor of accuracy of flexible coordinate measuring system which consists of universal industrial robot and visual sensor. Present compensation methods for positioning error based on kinematic model of robot have a significant limitation that it isn’t effective in the whole measuring space. A new compensation method for positioning error of robot based on vision measuring technique is presented. One approach is setting global control points in measured field and attaching an orientation camera to vision sensor. Then global control points are measured by orientation camera to calculate the transformation relation from the current position of sensor system to global coordinate system and positioning error of robot is compensated. Another approach is setting control points on vision sensor and two large field cameras behind the sensor. Then the three dimensional coordinates of control points are measured and the pose and position of sensor is calculated real-timely. Experiment result shows the RMS of spatial positioning is 3.422mm by single camera and 0.031mm by dual cameras. Conclusion is arithmetic of single camera method needs to be improved for higher accuracy and accuracy of dual cameras method is applicable.
In this paper, a new coordinate system calibration is proposed in order to define the dependence of position between object body coordinate and camera coordinate which can be used in object measurement by the formation of image. Due to existing the fabrication and installation error, it is difficult to make system parallel between object body coordinate and camera coordinate. To resolve it, the deviation of the two coordinate system is demanded to measure detailed. The deviation compensation in the image processing software can ensure the accuracy the pitch angle and azimuth in the destination image of camera measurement system. In order to definite the position, a base coordinate system of theodolite is set by mutual-space measurement principle. After the measurement of theodolite system, a transformation matrix of the base coordinate system can be deduced. Changing the position of the theodolite station and adjusting the cross-screw to infinity, the transformation matrix between the base coordinate and star-sensor coordinate can be deduced by image formation of the destination at infinity. The position relation between object body and camera can be calculated by the transformation matrix. The results of the measurement experiment show that the gauging repeatability is 6' which can meet the system gauging demands.
To the question of measuring the moving object pose, a high speed and high synchronization precision spatial pose measurement system based on optical measurement was designed. The system is more convenient and more accurate. In order to realize the measurement method, a Synchronous controller was used to keep the moving object and the pose measurement system based on binocular vision model synchronized. The system can record the course with high synchronization precision. Geometry constraint relation of the special markets and optimization algorithm based on coordinates of multi-points were used in the pose algorithm of the moving object. Experimental results and theoretical analysis prove that the pose measurement method is correct and reliable. The frequency of the pose measurement system is 100 frames per second. The error of the pose angle is less than 0.05°. The pose measurement system satisfies the requirements of pose measuring in ground simulation test.