Study On Micro-thruster Compensation System Based On Location With Machine Vision

Satellites and other spacecraft must be tested with a unique full-physical method before performing the space tasks in order to verify the performance and functions of control system. Ground full-physical simulation is a test to emulate the microgravity and frictionless motion environment for the spacecraft in space by using the air bearing simulation system on the granite test platform. The test platform is composed of granites which are inclined at different angles and directions. It will influence the accuracy of the simulation results. The possible solution is to overcome the component force of system gravity along inclined directions when the air bearing simulation system is on different granite. In this paper, it is controlled by providing the corresponding thrust compensation in full-physical simulation experiment.Aiming at the above-mentioned problem, a set of micro-thrust compensation system based on location with machine vision is studied and designed, and machine vision technology is applied to spacecraft design and test fields. This system is mainly composed of vision locating system and cold gas micro-thrust device, vision locating system acquires the scene images and obtains the location information of air bearing simulation system after a series of image processing, then micro-thrust device jets to compensate for the corresponding thrust. The characteristics of non-contact, fast and flexible of machine vision are fully utilized in this system, so the test process will not be interfered with.The study task of this paper includes machine vision technology, mechanical design, computer programming technology, etc. For machine vision locating system, camera calibration and vision location algorithm are focused on, for micro thrust device, realization of thrust control based on RS232 serial port is focused on. The paper mainly includes following four parts:(1) Vision locating system and cold gas micro-thrust device were designed concretely.(2) Camera calibration technology was studied, and camera imaging model and coordinate transformation were analyzed. According to the calibration method based on planar moving template, camera calibration experiment was done, and the parameters of the camera were determined.(3) The principle and method of vision locating system were studied, in the process of artificial mark position information extraction, image pre-processing (gray, filtering, binarization), edge detection, least square edge fitting algorithm precision were mainly used to obtain the location information of artificial mark.(4) Micro thrust control based on RS232 serial communication port was realized, and the man-machine interaction interface, named as "Beijing Jiaotong University Micro Platform Remote Location Control System", has been written. System software and hardware platform were used in field experiments, the experimental results proved that all parts of the system could finish their tasks well.