Over-Actuated Underwater Robots: Configuration Matrix Design and Perspectives.

Tho Dang,Rene Zapata,Pascal Lepinay,Benoit Ropars,Lionel Lapierre

doi:10.3390/s21227729

Abstract

In general, for the configuration designs of underwater robots, the positions and directions of actuators (i.e., thrusters) are given and installed in conventional ways (known points, vertically, horizontally). This yields limitations for the capability of robots and does not optimize the robot’s resources such as energy, reactivity, and versatility, especially when the robots operate in confined environments. In order to optimize the configuration designs in the underwater robot field focusing on over-actuated systems, in the paper, performance indices (manipulability, energetic, reactive, and robustness indices) are introduced. The multi-objective optimization problem was formulated and analyzed. To deal with different objectives with different units, the goal-attainment method, which can avoid the difficulty of choosing a weighting vector to obtain a good balance among these objectives, was selected to solve the problem. A solution design procedure is proposed and discussed. The efficiency of the proposed method was proven by simulations and experimental results.

Highlights

The Actuation System (AS) is an important part of marine robots
This paper focuses on the design of the actuator configuration for an overactuated underwater robot with the contributions outlined below: 1. We propose performance indices to evaluate the actuator configuration of underwater robots; 2
An approach for designing an optimal configuration matrix of overactuated underwater robots was presented

Summary

Introduction

The Actuation System (AS) is an important part of marine robots. The AS groups the different actuators carried by the system. The control system is in charge of computing the desired force (FdB) in order to reduce the error function to zero. Note that classically, this desired force is expressed in the body-frame. The dispatcher (D) considers the actuator allocation method (and eventually, redundancy management) to compute the desired actuator force (Fdm) that each actuator has to produce. The properties of the AS are dependent on the actuator configuration (position and attitude of the actuators with respect to the body-frame), actuator dynamics (response characteristics), and dispatcher (control allocation, redundancy management) (see Figure 2) and afford the system different properties. The domain of robotic manipulators has extensively studied this question of redundancy, especially with recent works on humanoid robotics, where the task function approach [6] has been used to concurrently achieve equilibriums [7], walking pattern following [8], and multicontact management [9]

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Results

Conclusion