Trajectory Tracking Control of an Underactuated Underwater Vehicle Redundant Manipulator System

Abstract

The purpose of this study is to control the position of an underactuated underwater vehicle manipulator system (U-UVMS). It is possible to control the end-effector using a regular 6-DOF manipulator despite the undesired displacements of the underactuated vehicle within a certain range. However, in this study an 8-DOF redundant manipulator is used in order to increase the positioning accuracy of the end-effector. The redundancy is resolved according to the criterion of minimal vehicle and joint motions. The underactuated underwater vehicle redundant manipulator system is modeled including the hydrodynamic forces for the manipulator in addition to those for the autonomous underwater vehicle (AUV). The shadowing effects of the bodies on each other are also taken into account when computing the hydrodynamic forces. The Newton-Euler formulation is used to derive the system equations of motion including the thruster dynamics. In order to establish the endeffector trajectory tracking control of the system, an inverse dynamics control law is formulated. The effectiveness of the control law even in the presence of parameter uncertainties and disturbing ocean currents is illustrated by simulations.

Analysis, Verification and Comparison on Feedback‐Aided MA Equivalence and Zhang Equivalency of Minimum‐Kinetic‐Energy Type for Kinematic Control of Redundant Robot Manipulators

“…It can be seen from Fig. 1a that the simulated motion trajectory of PUMA560 end-effector synthesized via ALMKE scheme (15) is sufficiently close to the prescribed tricuspid path, with the maximum component of end-effector position error in Fig. 1b being less than 1.6 × 10 −7 m. This illustrates that the tricuspid-path tracking task is completed successfully.…”

“…2d, the differences of joint-variable solutions are very tiny, with the minimum joint-angle and joint-velocity differences being less than 1.4 × 10 −6 rad and 5.6 × 10 −7 rad/s, respectively. Thus, in consideration of the fact that the digital computer used in the simulations is of finite precision and finite memory [29,57], together with the relative tolerance (RelTol) being 10 −6 and the absolute tolerance (AbsTol) being 10 −8 (involved in the ode15s), it is reasonable to conclude that VLMKE scheme (14) is mathematically equivalent to ALMKE scheme (15), which is also consistent with the theoretical result on the MKE-ME presented in Subsection 2.1.…”

“…A robot manipulator is the mechanical device that moves its end-effector in order to perform automated tasks [1][2][3][4][5][6][7][8][9][10][11][12][13]. As a special kind of robot manipulator, redundant manipulators are robots having more degrees of freedom (DOFs) than the required ones to execute a given end-effector primary task [14][15][16][17][18][19][20][21][22][23]. They are similar to the human arm, elephant trunk and snake in the real world [17,18,24].…”

“…They are similar to the human arm, elephant trunk and snake in the real world [17,18,24]. A fundamental issue in controlling redundant robot manipulators is the redundancy-resolution problem, which is related to the kinematic control of redundant robot manipulators and has attracted extensive attention in scientific researches and engineering applications [1,2,6,[14][15][16][17][18][19][20][21][25][26][27]. The general description of such a redundancy-resolution problem is that, given the desired end-effector Cartesian path r d (t) ∈ R m , the corresponding joint trajectory (t) ∈ R n needs to be generated in real time t. The conventional solution to the redundancy-resolution problem is the pseudoinverse-based method, which is formulated as one minimum-norm particular solution plus a homogeneous solution [21][22][23].…”

Modeling and Fuzzy Decoupling Control of an Underwater Vehicle-Manipulator System

“…Santhakumar [17] proposed a model reference control scheme for the UVMS. Korkmaz et al [18] presented an inverse dynamics control law for an underactuated UVMS (U-UVMS). Taira et al [19] developed a model-based control for the UVMS with one of the three types of servo subsystems.…”