Trajectory planning and multi-axis coordination of manipulator considering performance constraints of...

Hydraulic manipulators use a main control valve to distribute flow from a single pump to multiple actuators, enhancing the energy efficiency. However, this architecture causes electro-hydraulic system (EHS) performance constraints, such as flow saturation/coupling, cavitation, and valve spool stroke limitations, which can impair the coordination. To address these challenges, this paper proposes a novel framework for multi-axis coordination control. First, the non-dominated sorting genetic algorithm II is used to optimize the interpolated trajectory based on fifth-order B-splines in the joint space, which optimizes the motion reference. Second, to precisely follow the parameterized optimal trajectory, normalized guidance vector fields (GVFs) are constructed, and a convergence term is designed based on the Euclidean distance function to drive the system to globally and asymptotically converge to the target path. Lyapunov stability theory is used to prove the boundedness of the system under model uncertainties and external disturbances. The quantitative relationship between the disturbance intensity and the trajectory deviation is derived, and a singularity avoidance mechanism is proposed that ensures the uniqueness and continuity of the vector field corresponding to the end-effector trajectory control (ETC) in the global workspace solution. Finally, the performance constraints of the EHS are transformed into a real-time optimization problem, rather than relying on complex global optimizers. The GVF command is adjusted to change the velocity of the ETC in Cartesian space. The effectiveness of the proposed scheme is verified through simulations and experiments.