This work develops a fixed-time control scheme to address the tracking control problem for a wheeled mobile robot (WMR) in lumped disturbance conditions involving slipping, skidding, and external disturbances. A novel fixed-time velocity control law is first developed for the error kinematics of the WMR system based on an intermediate-term design. To ensure high-performance tracking for the generated velocity in lumped disturbance cases, the impacts of slipping and skidding are incorporated into the dynamics of the WMR system. A fixed-time trajectory tracking control law that integrates a fast fixed-time disturbance observer is also proposed. Specifically, the well-designed observer is developed to estimate the lumped disturbances. The proposed control scheme avoids the commonly existing singular problem and ensures that the error states of WMR can converge into a neighborhood of the origin within a fixed time during slipping and skidding. Based on comparison experiments, the proposed control scheme exhibits superior performance and effectiveness.

This work develops an improved integrated planning and control framework for an unmanned aerial vehicle (UAV) in complex environments with dense obstacles to achieve fast and accurate path planning, trajectory generation, and tracking control. Utilizing the potential function-based rapid-exploration random tree star (P-RRT*), a bidirectional dynamic informed P-RRT* (BDIP-RRT*) algorithm is first introduced to enhance sampling efficiency, facilitating swift path generation. To further optimize the initial path, a greedy algorithm is employed to minimize redundant segments within the generated path. Subsequently, trajectory control points are assigned based on the original path points using an adaptive distance interpolation strategy. A hybrid optimized trajectory generator considering jerk and snap is built to obtain a reference trajectory for the UAV. Moreover, two prescribed-time control laws are designed to ensure fast and accurate UAV position and attitude control. Finally, simulation results are performed to illustrate the effectiveness and superior performances of the developed path planning and control scheme.