# Maximising the wrench capability of mobile manipulators with experiments on a UVMS

## TL;DR

This paper introduces new methods to optimize underwater robot systems for maximum force and torque in specific tasks like lifting and turning valves.

## Contribution

A bi-level optimization framework is proposed to maximize wrench capability in underwater vehicle manipulator systems.

## Key findings

- The proposed method significantly increases wrench capability compared to existing approaches.
- Experimental results validate the effectiveness of the method on a 6DOF underwater robotic platform.
- Dynamic motions enable large wrench impulses for tasks like valve turning and heavy lifting.

## Abstract

This paper presents methods for finding optimal configurations and actuator forces/torques to maximise contact wrenches in a desired direction for underwater vehicle manipulator systems (UVMS). The wrench maximisation problem is formulated as a bi-level optimisation problem, with upper-level variables in a low-dimensional parameterised redundancy space, and a linear lower-level problem. We additionally consider the cases of one or more manipulators with multiple contact forces, maximising the wrench capability while tracking a trajectory and generating large wrench impulses using dynamic motions. The specific cases of maximising force to lift a heavy load and maximising torque during a valve-turning operation are considered. Extensive experimental results are presented using a 6 degree of freedom (DOF) underwater robotic platform equipped with a 4DOF manipulator and show significant increases in the wrench capability compared to existing methods for mobile manipulators.