Research On Optical Sensor Parameters Calibration Technology For Space Rendezvous And Docking

With the increasing development of computer vision，a position and orientationmeasurement system based on optical sensors has been widely studied and used in thespace rendezvous and docking due to its high efficiency and simple structure. Whetherthe system performs well or not directly affects the result of space docking. As the keystep of position and orientation measurement, the stability of the algorithm and theresults in the process of calibration of the sensor’s parameters directly influence theaccuracy of measurement. For this, by analyzing the optical sensor, this subjectdiscusses some effective ways of calibration of parameters, which make a difference toincrease the accuracy of measurement.In the parameters of optical sensors，the distortion which only has a connect withthe optical centers, is relatively independent. The traditional ways of calibration usuallycombine the coefficients of distortion and other parameters together to solve，but theprinciple is complex, time wasteful and accuracy low. For this, the subject brings up anew idea based on the combination of calibration of distortion independently andnonlinear optimization. Firstly, using the co-linearity and invariance of cross-ratio of thepoints in the virtual template to correct the distortion, and then basing on the imagewithout distortion to optimize other parameters of the optical sensor. This idea avoidsthe influence of the distortion on other parameters, thus increasing the accuracy of theposition and orientation measurement system.The position and orientation measurement system usually has a short base-linedistance, so with the increasing of the measurement distance, the error is expandedsharply. For this, the subject come up with an idea of calibration by dividing entiremeasurement range into several areas, aiming at increasing the accuracy in the case ofthe shorter base line distance by choosing the relatively accurate parameters to measure.Both the simulations and the overall testing experiments proved the correctness andefficiency of the two ideas. And by using these two methods, the accuracy ofmeasurement is increased.