The Research On The Method Of Imaging Plane Installation And Calibration Of Star Sensor

Star sensor is a kind of space attitude measurement device with high precision,which use the fixed star as the reference system and the working object.It has the advantages of high accuracy,high sensitivity and doesn't have attitude accumulation error,so it is a kind of high precision attitude sensor.In order to ensure the measurement accuracy of star sensor,the accuracy of the assembly process and accurate calibration for the star sensor is essential.The core functional components of the star sensor are the detector(it refers mainly to the image sensor)and the optical system lens.The assembly precision of the two parts directly influences the imaging quality and the detection accuracy of the star sensor.Among them,the tilt angle and the rotation angle of the imaging plane of the detector,and the distance between the imaging plane and the focal plane of the lens are the main parameters.In this paper,we mainly describe the installation and calibration device for the focal plane of the imaging element in star sensor,and the detection and verification of the above parameters are realized.The device is used to carry on the functions including the best imaging plane determination and verification of the star senor.The best imaging plane is determined by the two processes including the attitude detection and the detection of the off-focus distance of the detector,and the attitude detection is composed by the tilt angle and the rotation angle detection.Using the pre-calibrated installation datum on the star sensor,the laser triangulation method and the plane fitting based on least square method are used in this paper to detect the tilt angle,the image edge extraction is used to detect the rotation angle.Meanwhile,according to the Gauss optical principle,a collimator measuring the off-focus distance is designed.On the basis of offset distance between the pointolite and the focal plane of the collimator,off-focus distance can be calculated.According to the parameters obtained in the above steps,the focusing ring can be processed,and then the ring will be installed between the detector and the optical system of the star senor in order to realize the accurate installation position and the off-focal distance adjustment.Finally,a collimator array including six collimator is designed to simulate the stars with a fixed angular between each other,and the collimator array is arranged by two rows and three columns.The collimator array is used to verify the off-focal imaging effect of the star sensor with the focusing ring.