Variable Trajectory Impedance: A Super-Twisting Sliding Mode Control Method for Mobile Manipulator Based on Identification Model

Active compliance control represents a pivotal technique for managing the interplay between forces and positions. This article proposes an adaptive approach based on an identified model for variable trajectory control. Addressing parameter redundancy in the dynamic model, we propose a simplified, friction-incorporated modeling method. Key parameters are identified through current and torque data, with three friction models designed to approximate real-world scenarios. A method for monitoring instability risks is presented, particularly effective when the mass difference between the manipulator and the mobile platform is relatively small. It monitors imprudent power output, reducing risks such as overturning. Finally, within system safety constraints, an impedance model is designed to manage the relationship between external forces and position in Cartesian space. This model extends the range of motion to counteract external force influence, utilizing a trajectory modulation technique. Additionally, a trajectory tracking controller based on super-twisting sliding mode control is designed, and the stability of the control system is analyzed. Experimental validation confirms the efficacy of the proposed methodology.