Stochastic Fault-Tolerant Attitude Tracking and Control Allocation of Overactuated Spacecraft

This work presents an integrated approach for attitude tracking control and fault-tolerant control allocation of overactuated spacecraft, where the high-level controller addresses stochastic input disturbances, and the low-level control allocation manages actuator faults and uncertainties in fault estimation. The proposed stochastic attitude tracking controller, developed through the backstepping method, ensures asymptotic stability in probability. A stochastic control Lyapunov-function-based quadratic program is utilized to limit the high-level control input within the bounds of actuator torque limits. To account for inaccuracies in actuator fault estimation, the stochastic fault-tolerant control allocation is framed as a probabilistic optimization problem. To resolve this, we propose a novel approach to transform the probabilistic constraints into deterministic equivalents, reformulating the problem into a quadratically constrained quadratic programming framework. The effectiveness and performance of the proposed framework are demonstrated through comprehensive numerical simulations and comparisons with existing methods.