Dynamic trajectory planning of underwater hydraulic manipulator in joint space

7-Function underwater hydraulic manipulator can be mounted on underwater vehicles such as ROVs to achieve underwater operation. When the underwater vehicle is hovering in the sea, the target is in dynamic motion state compared to the vehicle position, which makes difficult for operators to accomplish dynamic operation task. Based on the underwater hydraulic manipulator structure characteristics, joint angle, joint angular velocity and total flow constraints are analyzed for manipulator trajectory generation. Cubic B-spline is applied to generate joint trajectories. To generate dynamic target trajectories, a method that can modify control points by calculating adjacent control points' intervals to fit the dynamic target is proposed. It can easily achieve synchronization and does not need to determine the total execution time before operation. Simulation experiments are performed to verify the efficacy of the proposed algorithm.