Controller Design and Experiment for Tracking Mount of Movable SLR, ARGO-M

Controller design procedure for prototype tracking mount of Movable SLR (Satellite Laser Ranging), ARGO-M is presented. Tracking mount of ARGO-M is altitude-azimuth type and it has two axes of elevation and azimuth to control its position. Controller consists of velocity and acceleration feed-forward controller, position controller at outer loop, velocity controller at inner loop. There are two kinds of position control modes. One is the pointing mode to move from one position to the other position as fast as possible and the other one is tracking mode to follow SLR trajectory as precise as possible. Because the requirement of tracking accuracy is less than 5 arcsec and it is very tight error budget, a sophisticated controller needs to be prepared to meet the accuracy. Especially, ARGO-M is using the cross-roller bearing at each axis to increase the mechanical accuracy, which requires add-on controller DOB (Disturbance observer) to suppress friction load and low frequency disturbances. The pointing and tracking performance of the designed controller is simulated and visualized using MATLAB/ Simulink and SimMechanics and the experimental results using test are presented as well.