scholarly journals Experimental validation of end-effector stabilization for underwater vehicle-manipulator systems in subsea operations

2018 ◽  
Vol 109 ◽  
pp. 1-12 ◽  
Author(s):  
Bent Oddvar A. Haugaløkken ◽  
Erlend K. Jørgensen ◽  
Ingrid Schjølberg
Keyword(s):  
Experimental Validation ◽  
Underwater Vehicle ◽  
End Effector

Experimental Validation of the Kinematics of a 3PRS Compliant Mechanism for Micromilling

2015 ◽  
Author(s):  
Antonio Ruiz ◽  
Francisco Campa Gomez ◽  
Constantino Roldan-Paraponiaris ◽  
Oscar Altuzarra
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Compliant Mechanism ◽  
Motion Controller ◽  
End Effector ◽  
Compliant Joints ◽  
Hybrid Manipulator ◽  
Compliant Parallel Mechanism ◽  
Actuated Joints

The present work deals with the development of a hybrid manipulator of 5 degrees of freedom for milling moulds for microlenses. The manipulator is based on a XY stage under a 3PRS compliant parallel mechanism. The mechanism takes advantage of the compliant joints to achieve higher repetitiveness, smoother motion and a higher bandwidth, due to the high precision demanded from the process, under 0.1 micrometers. This work is focused on the kinematics of the compliant stage of the hybrid manipulator. First, an analysis of the workspace required for the milling of a single mould has been performed, calculating the displacements required in X, Y, Z axis as well as two relative rotations between the tool and the workpiece from a programmed toolpath. Then, the 3PRS compliant parallel mechanism has been designed using FEM with the objective of being stiff enough to support the cutting forces from the micromilling, but flexible enough in the revolution and spherical compliant joints to provide the displacements needed. Finally, a prototype of the 3PRS compliant mechanism has been built, implementing a motion controller to perform translations in Z direction and two rotations. The resulting displacements in the end effector and the actuated joints have been measured and compared with the FEM calculations and with the rigid body kinematics of the 3PRS.

scholarly journals Evolutionary design of magnetic soft continuum robots

2021 ◽  
Vol 118 (21) ◽  
pp. e2021922118
Author(s):  
Liu Wang ◽  
Dongchang Zheng ◽  
Pablo Harker ◽  
Aman B. Patel ◽  
Chuan Fei Guo ◽  
...  
Keyword(s):  
Experimental Validation ◽  
Magnetic Particles ◽  
Permanent Magnets ◽  
Complex Geometry ◽  
Nonuniform Distribution ◽  
Evolutionary Design ◽  
Efficient Design ◽  
Continuum Robots ◽  
End Effector ◽  
Design And Optimization

Worldwide cardiovascular diseases such as stroke and heart disease are the leading cause of mortality. While guidewire/catheter-based minimally invasive surgery is used to treat a variety of cardiovascular disorders, existing passive guidewires and catheters suffer from several limitations such as low steerability and vessel access through complex geometry of vasculatures and imaging-related accumulation of radiation to both patients and operating surgeons. To address these limitations, magnetic soft continuum robots (MSCRs) in the form of magnetic field–controllable elastomeric fibers have recently demonstrated enhanced steerability under remotely applied magnetic fields. While the steerability of an MSCR largely relies on its workspace—the set of attainable points by its end effector—existing MSCRs based on embedding permanent magnets or uniformly dispersing magnetic particles in polymer matrices still cannot give optimal workspaces. The design and optimization of MSCRs have been challenging because of the lack of efficient tools. Here, we report a systematic set of model-based evolutionary design, fabrication, and experimental validation of an MSCR with a counterintuitive nonuniform distribution of magnetic particles to achieve an unprecedented workspace. The proposed MSCR design is enabled by integrating a theoretical model and the genetic algorithm. The current work not only achieves the optimal workspace for MSCRs but also provides a powerful tool for the efficient design and optimization of future magnetic soft robots and actuators.

Vision- based control of a mobile manipulator with an adaptable-passive suspension for unstructured environments

2021 ◽  
pp. 1-38
Author(s):  
Antonio Cardenas ◽  
Osmar Quiroz ◽  
Ricardo Hernandez ◽  
Hugo I. Medellin-Castillo ◽  
Alejandro González ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Experimental Validation ◽  
Experimental Tests ◽  
Mobile Manipulator ◽  
Robotic Platform ◽  
Kinematic Synthesis ◽  
End Effector ◽  
Uneven Terrain ◽  
Passive Mechanism ◽  
Position And Orientation

Abstract The kinematic design and navigation control of a new autonomous mobile manipulator for uneven terrain is presented in this work. An innovative suspension system's design is based on the kinematic synthesis of an adaptable, passive mechanism that compensates for irregularities in the terrain and facilitate the control of the robotic platform using cameras. The proposed mobile robot suspension consists of two pairs of bogies joined by a crank-slider mechanism that allows the robot to adapt to the terrain irregularities. The mobile robot is also equipped with a robotic manipulator, of which a synthesis, simulation, and experimental validation are presented while manipulation is accomplished during movements on rough terrain. The proposed mobile robot has been fabricated using additive manufacturing (AM) techniques. A linear camera space manipulation (LCSM) control system has been developed and implemented to conduct experimental tests along uneven terrain. This mobile manipulator has been designed to transverse uneven terrain so that the loading platform is kept horizontal while crossing obstacles up to one-third of the size of its wheels. This feature allows the onboard cameras to stay oriented towards the target. The vision-based paradigm that enables the control of this mobile manipulator allows to estimate the position and orientation of its end effector and update the trajectory of the manipulator along the path towards the target. The experiments show a final precision for engagement of a pallet within +/− 2.5 mm in position and +/− 2 degrees in orientation.

Dynamic Analysis of the UVMS: Effect of Disturbances, Coupling, and Joint-Flexibility on End-Effector Positioning

Robotica ◽  
2021 ◽  
pp. 1-29
Author(s):  
Umer Hameed Shah ◽  
Mansour Karkoub ◽  
Deniz Kerimoglu ◽  
Hong-Du Wang
Keyword(s):  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Added Mass ◽  
Hydrodynamic Forces ◽  
Viscous Damping ◽  
End Effector ◽  
Flexible Joint ◽  
Lagrange Formulation ◽  
System Coupling ◽  
Flexible Joint Manipulator

SUMMARY This paper investigates the dynamics of an underwater vehicle-manipulator system (UVMS) consisting of a two-link flexible-joint manipulator affixed to an autonomous underwater vehicle. The quasi-Lagrange formulation is utilized in deriving a realistic mathematical model of the UVMS considering joints’ friction, hysteretic coupling between the joints and links, and the nonlinear hydrodynamic forces acting on the system, such as added mass, viscous damping, buoyancy, drag, and vortex-induced forces. Numerical simulations are performed to demonstrate the effects of hydrodynamic forces and system coupling between the vehicle and the manipulator and the joints and the links on the precise positioning of the end effector.

scholarly journals Application of Adaptive and Switching Control for Contact Maintenance of a Robotic Vehicle-Manipulator System for Underwater Asset Inspection

2021 ◽  
Vol 8 ◽  
Author(s):  
Kamil Cetin ◽  
Carlos Suarez Zapico ◽  
Harun Tugal ◽  
Yvan Petillot ◽  
Matthew Dunnigan ◽  
...  
Keyword(s):  
Contact Interaction ◽  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Adaptive Controller ◽  
Underwater Vehicle ◽  
Tracking Algorithm ◽  
Superior Performance ◽  
Physical Interaction ◽  
End Effector ◽  
Force Tracking

The aim of this study is to design an adaptive controller for the hard contact interaction problem of underwater vehicle-manipulator systems (UVMS) to realize asset inspection through physical interaction. The proposed approach consists of a force and position controller in the operational space of the end effector of the robot manipulator mounted on an underwater vehicle. The force tracking algorithm keeps the end effector perpendicular to the unknown surface of the asset and the position tracking algorithm makes it follow a desired trajectory on the surface. The challenging problem in such a system is to maintain the end effector of the manipulator in continuous and stable contact with the unknown surface in the presence of disturbances and reaction forces that constantly move the floating robot base in an unexpected manner. The main contribution of the proposed controller is the development of the adaptive force tracking control algorithm based on switching actions between contact and noncontact states. When the end effector loses contact with the surface, a velocity feed-forward augmented impedance controller is activated to rapidly regain contact interaction by generating a desired position profile whose speed is adjusted depending on the time and the point where the contact was lost. Once the contact interaction is reestablished, a dynamic adaptive damping-based admittance controller is operated for fast adaptation and continuous stable force tracking. To validate the proposed controller, we conducted experiments with a land robotic setup composed of a 6 degrees of freedom (DOF) Stewart Platform imitating an underwater vehicle and a 7 DOF KUKA IIWA robotic arm imitating the underwater robot manipulator attached to the vehicle. The proposed scheme significantly increases the contact time under realistic disturbances, in comparison to our former controllers without an adaptive control scheme. We have demonstrated the superior performance of the current controller with experiments and quantified measures.

scholarly journals Dynamics Simulation of Grasping Process of Underwater Vehicle-Manipulator System

2020 ◽  
Author(s):  
Zong-Yu Chang ◽  
Yang Zhang ◽  
Zhong-Qiang Zheng ◽  
Lin Zhao ◽  
Kun-Fan Shen
Keyword(s):  
Attitude Control ◽  
Coupling Effect ◽  
Underwater Vehicle ◽  
Vehicle Control ◽  
Dynamics Simulation ◽  
End Effector ◽  
Floating Base ◽  
Coupling Dynamics ◽  
Commercial Applications ◽  
Marine Exploration

Abstract Underwater vehicle-manipulator system (UVMS) can be applied to fulfill different complex underwater tasks such as grasping, drilling, sampling, etc. It is widely used in the field of oceanographic research, marine exploration, military and commercial applications. In this paper, the dynamic simulation of UVMS is presented in the process of grasping an object. Firstly, the dynamic model of UVMS, which considers the change of the load of manipulator when the end effector of manipulator grasps the object, is developed. To compare different control conditions, the numerical simulation of grasping processes without/with vehicle attitude control are carried out. The results show that the coupling dynamics between the vehicle and the manipulator in the grasping process are clearly illustrated. The tracking position error of end effector without vehicle control is large and UVMS cannot complete the grasping task under this condition. Vehicle control can compensate the motion of vehicle due to the coupling effect caused by the motion of manipulator. This study will contribute to underwater operation mission for UVMS with floating base.

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