Research On Probe Movement Of Three-Axis Positioning Platform For Circuit Board Testing

With the development of electronic science and technology,circuit test system is gradually changing from semi-automatic test systems to fully automated test systems.In a fully automated circuit board test system,the role of the three-axis positioning platform is to drive the test probe to move to the point to be measured and complete the corresponding electrical measurement task.After researching three-axis positioning platform,this paper has designed the probe motion feedback system and carried out the probe motion trajectory planning for the defects of the platform probe motion system.The main work are as follows:Firstly,the XY plane probe motion feedback system is designed for the problem that the accuracy of the three-axis positioning platform XY plane probe is not high.The system uses the grating ruler as the position detection element,uses STM32 to process the output signal of the grating ruler,acquires the actual position information of the probe,the feedback system will compare the actual position information with the preset position information,if the deviation between the two,the system will carry out the error correction process.In addition,in order to further improve the probe's movement accuracy,starting from the trajectory of the probe,the linear interpolation algorithm is studied,and the trajectory of the probe is fitted into a straight line.At the same time,improved interpolation rules and interpolation point selection rules for interpolation algorithms because the original interpolation algorithm causes uneven probe movement.Second,in order to solve the problem of Z-axis motion of the positioning platform,a Z-axis motion feedback system was designed.The system uses an infrared distance sensor to measure the real-time distance between the probe and the circuit board.Once the detected distance reaches the threshold range,the probe's motion is immediately stopped.The system can stop the probe in a proper position,which can not only guarantee the reliable contact between the probe and the circuit board to be tested,but also reduce the impact of the probe on the circuit board.Finally,the above feedback system is built on the existing three-axis positioning platform,and experimental tests are performed to verify the accuracy of each system.Theimproved three-axis positioning platform is applied to the circuit board automatic testing system for joint testing.Test results show that the improved three-axis positioning platform can accurately complete the positioning test task of the probe and realize the automatic test function of the circuit board.