A Shared Control Framework With Constrained Optimization and Guiding Force Feedback for Teleoperation of Underwater Electric Manipulator

Human-in-the-loop teleoperation is a commonly used strategy for accomplishing underwater tasks by remotely controlling an underwater electric manipulator (UEM). However, nonlinearities and various uncertainties caused by hydrodynamics in UEM, poor tracking accuracy, as well as physical constraints and communication delays, pose significant challenges to the implementation of underwater teleoperation with UEM. Therefore, this article proposes a shared control framework for UEM teleoperation, incorporating constrained optimization and guiding force feedback to enhance underwater operation efficiency and reduce the operator's workload. Namely, an adaptive robust controller is developed on the remote side to ensure accurate tracking of the UEM in the underwater environment. Since the operator's commands are not available in advance and may violate the physical constraints of the UEM, an online constraint planner, which considers the constraints via the jerk-level configuration transformation strategy, is designed to generate feasible trajectories to be tracked by the UEM. Furthermore, constraints are taken into account in the guiding force feedback design, which can provide the operator with haptic feedback when constraints are violated, thereby preventing the operator from issuing unsafe commands and ensuring the effective implementation of underwater teleoperation. Finally, the modified wave variable architecture is employed to complete the teleoperation control, ensuring system stability even in the presence of communication delays between the onboard operator and UEM. Comparative experiments with a user study are conducted in a real underwater environment to evaluate the effectiveness of the proposed shared control framework.