Design, Modeling and Control of a Spherical Autonomous Underwater Vehicle for Mine Exploration

Abstract

This paper presents the design, implementation and validation of a novel spherical Autonomous Underwater Vehicle (AUV) prototype, developed for inspection and exploration of flooded mine tunnel networks. The unique mechanical, electrical and hardware design is presented, as well as the development of a theoretical 6 degree-of-freedom (DOF) highfidelity dynamic model of the system. A series of underwater experiments were carried out in a controlled environment to test the standard motion patterns of the AUV with a Proportional-Integral-Derivative (PID) controller. The performance of the PID controller will be used as the baseline for comparison of more advanced control schemes. The experimental results demonstrated that the spherical AUV was able to realize the tested underwater motions with notable performance.

Nonlinear Attitude Control of a Spherical Underwater Vehicle

“…The experimental tests were designed to compare the performance of the FL controller, presented in Section 4.1, with the PID controller previously implemented and tested in [23] for a regulation problem scenario [32]. Thus, by comparing the ability of the UV to reach and maintain a desired position for longitudinal motions and heading control, an appropriate controller can be chosen for implementation in the real UX-1 robot.…”

“…For efficiency in design, development, and testing of the UV prototype, low-cost COTS mechanical and electronic components were used, when available, so that any component damaged during testing could be easily replaced. The final prototype’s mechanical and electronic design has been thoroughly explained in [23] and can be divided into three main components, which are: external hull, manifold system for propulsion and a pendulum mechanism for pitch movement.…”

“…The 6 DOF equations of motion for an UV are derived according to the SNAME nomenclature [25]. Given that for the experiments performed in this work the UV is not meant to be actuated in all degrees of freedom, reduced order models are presented for longitudinal motion (Section 3.2.1) and lateral motion (Section 3.2.2), such as in [23]. As can be seen in Figure 6, we make use of an inertial frame in NED configuration {n}, with orthonormal basis {xn, yn, zn} and origin on represented in world coordinates, as well as the body-fixed reference frame {b} with orthonormal basis {xb, yb, zb} and origin ob also in world coordinates.…”

“…Furthermore, this value has been chosen as the maximum normal operating speed for the UX-1 robot during future exploration missions. We consider the nonlinear equations of motion developed in [23,26] for an UV:trueη˙=JΘ(η)boldν bold-italicMtrueν˙+bold-italicC(ν)boldν+bold-italicD(ν)boldν+g(η)=boldτ with:boldη=[]Pb/nnΘnb=[x,y,z,ϕ,θ,ψ]⊤ JΘ(η)=[]bold-italicRbn(Θnb)03×303×3bold-italicTΘ(Θnb) …”

“…The spherical UV prototype was developed to test advanced control algorithms before implementing them in the UX-1 system during future mine site tests. In this work a State Feedback Linearization (FL) control algorithm is implemented and compared to a baseline controller developed and tested previously in [23].…”