Satellite Payload Motion for Remote Sensing

The paper presented below discusses the scanning motion of payloads on satellites in the context of multi body dynamics, the control systems used to control the scan motion and their effect on image stability, jitter and pointing accuracy. Remote Sensing Satellites usually have a number of payloads and each of them scans in a specific manner as determined by its purpose. This scanning motion has an effect on the spacecraft itself, and the attitude motion produced will thus disturb the payload's motion causing jitter and change in the image being recorded in the payload. The satellite must have adequate attitude control in order to cancel out these motions and meet the pointing accuracy and stability requirements as demanded by the payload.The geometry of the scan mechanisms are presented in order to derive their ideal ground track (representing image recorded by the payload), and to calculate the ideal in-track, cross-track or other angle profile that must be generated by the scan mechanism to obtain that ground track. A simulation of the multi-body system is presented, using the equations of motion on the satellite and its payload. A control system is then added to the payload which is articulated to the satellite in order to produce the above motion and another control system is added to the satellite in order to maintain its stability and compensate for all the disturbing torques produced by satellite scan mechanisms.We investigate if the motion produced meets the requirements for pointing accuracy and jitter stability for the payload, and if not, develop strategies to modify the control systems in order to accomplish this.