Research on Disturbance Rejection Control Algorithm for Aerial Operation Robots

Aims: external interference and slow localization response. The primary objective is to propose an algorithm that integrates admittance control and non-singular fast terminal sliding mode control, verifying its effectiveness through simulation experiments while exploring its potential for patent application. Background: Due to their versatility and efficiency, UAVs are increasingly utilized in various aerial operations. However, they are susceptible to external disturbances, which may affect their stability and accuracy during tasks such as contact operations. Additionally, inherent delays in localization response speed may impact their performance in dynamic environments. Addressing these issues is essential for improving the reliability and robustness of UAV-based systems. Methods: To achieve the objectives, the kinematics and dynamics of a hexacopter aerial carrier robotic arm system were initially modeled. Subsequently, an external admittance controller was designed to mitigate disturbances encountered during contact operations, achieving smooth control of the robotic arm end-effector by adjusting the desired position to enhance system stability and disturbance rejection. Additionally, to prevent performance degradation stemming from controller saturation, an internal position control mechanism utilizing a non-singular fast terminal sliding mode control algorithm was implemented. This approach enhances system robustness and convergence speed, ensuring accurate positioning. Results: To validate the effectiveness and feasibility of the proposed control algorithm, numerical simulations were conducted. The outer loop's admittance control exhibited a smoother control process, particularly during sudden stiffness changes when the actuator contacts the environment. The inner loop, employing Non-Singular Fast Terminal Sliding Mode Control (NFTSMC), improved joint angle tracking speed by 41%-58% compared to PID control, and by 20%-50% compared to traditional Sliding Mode Control (SMC). This algorithm demonstrated faster convergence rates and smoother transitions, significantly reducing steady-state errors in contact force while exhibiting robustness to environmental parameters. The findings indicate that the algorithm effectively addresses the issues of external interference and sluggish localization response encountered by UAVs during aerial operations. Conclusion: The algorithm based on admittance control and non-singular fast terminal sliding mode control demonstrates superior performance compared to traditional sliding mode control and PID control in mitigating external disturbances and enhancing the precision of UAV aerial operations. This ensures the resilience to disturbances and the speed of localization response of the rotary- wing flying robotic arm system during cleaning processes, thus enhancing its reliability and robustness in dynamic environments.