Hyperbolic Tangent Sliding Mode Control for Aerial Manipulator Contact Operations Based on Third-Order Sliding Mode Observer
Bin Yang, Xinghua Miao · 2024
In contact tasks, aerial manipulators are influenced by time-varying forces and moments transmitted from the manipulated object. These disturbances can compromise system stability and control precision. Traditional force feedback control methods, commonly used in industrial robotic arms, are ineffective in the aerial manipulator environment due to sensor limitations. To address this issue, this paper integrates a third-order sliding mode observer and an admittance controller into the classical control framework of aerial manipulators. The sliding mode observer estimates the time-varying external forces during contact tasks, while the admittance controller generates the corresponding reference trajectory for the end-effector. This trajectory is used as the input for the outer-loop position controller of the flying platform. Furthermore, the single degree-of-freedom arm swing angle is incorporated as an extended parameter in the inner-loop attitude control, with both inner and outer loops employing hyperbolic tangent sliding mode controllers. Simulation results indicate that the proposed control strategy achieves improved contact stability and trajectory tracking performance under continuously varying external forces.