PHASE-PLANE CONTROL ALGORITHM WITH ADAPTIVE MINIMUM-IMPULSE BIT INTEGRAL CONTROL

The JPL-heritage proportional-derivative (PD) phase-plane control algorithm is augmented with a new algorithm that incorporates integral control action for purposes of minimizing: (i) pulse counts and (ii) the time-averaged pointing error signal. Because of the deadzone present in all JPL-heritage thruster-based phase-plane control designs, the introduction of integral action into previous proportional-integral-derivative (PID) controllers has been problematic. (Of course, PID is simple to implement in the absence of a deadzone.) In this work, a stabilizer function is introduced which compares the (always stabilizing) PD control signal with the (sometimes desirable) PID control signal. In particular, when these two signals are in harmony (i.e., correlated in sign), the PID signal is utilized. On the other hand, when the PD and PID signals do not align (in sign), it can be shown that it is best to nullify the output of the controller. Simulation results are presented which demonstrate: (i) the stability of the algorithm and (ii) the minimum pulse-count and pointing error objectives.