Disturbance observer-based saturated fixed-time pose tracking for feature points of two rigid bodies

The relative pose dynamics for the feature points of two nearby rigid bodies is modeled in the body-fixed coordinated system of the controlled chaser. Then, a novel model-based fixed-time relative motion controller is developed for the active chaser to achieve the target’s feature-point position tracking and attitude synchronization under constrained control inputs and model uncertainties. In particular, the convergence time of system states is prescribed independently with initial states and estimated by the control parameters. A fixed-time disturbance observer is introduced to estimate and compensate unknown bounded disturbances, and the observation errors converge to zero in fixed time. A novel fixed-time anti-windup compensator is proposed to deal with the actuator saturation. Theoretical analysis and simulation results validate the effectiveness of the proposed controller.