Low Earth Orbit Satellite Attitude Stabilization Using Linear Quadratic Regulator

This study compares the result of the PID controller to the LQR controller when used in the on-orbit stabilization of a satellite in the low earth orbit. The results from the PID controller show that the controller is too weak when used alone as the controller could not stabilize the system after 500 s which is not even allowable in practical application. For the LQR controller, a performance metric was set which is: i. the settling time is to be ≤ 10 seconds, ii. Maximum power consumption ≤ 1.5 Watts and iii. Zero (0) steady-state error / final value. The LQR controller meets system performance by achieving a settling time of roll (peak amplitude=0.26 s, settling time=10.0 s), Pitch (peak amplitude=0.395 s, settling time=5.52 s), Yaw (peak amplitude=0.350 s, settling time=5.52 s) and Total power consumption are 1.26 watt with a maximum torque of 3.22 mNm. Because power consumption and precision are critical in satellite applications, particularly military surveillance satellites. As a result, for an aerospace engineer to achieve their space mission, for instance, space mission like low earth orbit surveillance satellites, flexible solar panels, a high accuracy pointing accuracy, it will be impossible to adopt a PID controller except the engineer is ready for the complexity of design filters and compensators. An LQR design in this study can take care of all this complexity with minimum power consumption.