scholarly journals Optimal Image-Based Guidance of Mobile Manipulators using Direct Visual Servoing

Electronics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 374 ◽  
Author(s):  
Álvaro Belmonte ◽  
José Ramón ◽  
Jorge Pomares ◽  
Gabriel Garcia ◽  
Carlos Jara
Keyword(s):  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Mobile Manipulator ◽  
Robot Dynamics ◽  
Mobile Manipulators ◽  
Control Force ◽  
Robot Arm ◽  
Dynamical Behaviors ◽  
Control Framework ◽  
Image Trajectories

This paper presents a direct image-based controller to perform the guidance of a mobile manipulator using image-based control. An eye-in-hand camera is employed to perform the guidance of a mobile differential platform with a seven degrees-of-freedom robot arm. The presented approach is based on an optimal control framework and it is employed to control mobile manipulators during the tracking of image trajectories taking into account robot dynamics. The direct approach allows us to take both the manipulator and base dynamics into account. The proposed image-based controllers consider the optimization of the motor signals sent to the mobile manipulator during the tracking of image trajectories by minimizing the control force and torque. As the results show, the proposed direct visual servoing system uses the eye-in-hand camera images for concurrently controlling both the base platform and robot arm. The use of the optimal framework allows us to derive different visual controllers with different dynamical behaviors during the tracking of image trajectories.

Cooperation and Null-Space Control of Networked Omni-Directional Mobile Manipulators

2020 ◽  
Author(s):  
Michael John Chua ◽  
Yen-Chen Liu
Keyword(s):  
Degrees Of Freedom ◽  
Null Space ◽  
Kinematic Model ◽  
Mobile Manipulator ◽  
Main Task ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
Task Space ◽  
End Effector ◽  
Mobile Base

Abstract This paper presents cooperation and null-space control for networked mobile manipulators with high degrees of freedom (DOFs). First, kinematic model and Euler-Lagrange dynamic model of the mobile manipulator, which has an articulated robot arm mounted on a mobile base with omni-directional wheels, have been presented. Then, the dynamic decoupling has been considered so that the task-space and the null-space can be controlled separately to accomplish different missions. The motion of the end-effector is controlled in the task-space, and the force control is implemented to make sure the cooperation of the mobile manipulators, as well as the transportation tasks. Also, the null-space control for the manipulator has been combined into the decoupling control. For the mobile base, it is controlled in the null-space to track the velocity of the end-effector, avoid other agents, avoid the obstacles, and move in a defined range based on the length of the manipulator without affecting the main task. Numerical simulations have been addressed to demonstrate the proposed methods.

scholarly journals Using FPGA Design and HIL Algorithm Simulation to Control Visual Servoing

2018 ◽  
Vol 6 (2) ◽  
pp. 111
Author(s):  
Lway Faisal Abdulrazak ◽  
Zaid A. Aljawary
Keyword(s):  
Object Tracking ◽  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Optimal Solution ◽  
Robot Dynamics ◽  
Fpga Design ◽  
Joint Torques ◽  
Array Technology ◽  
Gate Array ◽  
Set Up

<span style="font-size: 9pt; font-family: 'Times New Roman', serif;">This is a novel research paper provides an optimal solution for object tracking using visual servoing control system with programmable gate array technology to realize the visual controller. The controller takes in account the robot dynamics to generate the joint torques directly for performing the tasks related to object tracking using visual servoing. Also, the notion of dynamic perceptibility provides the capability of the designed system to track desired objects employing direct visual servoing technique. This idea is assimilated in the suggested controller and realized in the programmable gate array. Additionally, this paper grants an ideal control framework for direct visual servoing robots that incorporates dynamic perceptibility features. With the aim of evaluating the proposed FPGA based architecture, the control algorithm is applied to Hardware-in-the-loop simulation (HIL) set up of three degrees of freedom rigid robotic manipulator with three links. Furthermore, different investigations are performed to demonstrate the behavior of the proposed system when a trajectory adjacent to a singularity is attained.</span>

Design, Analysis, and Applications of Mobile Manipulators

2018 ◽  
pp. 26-65
Author(s):  
Tao Song ◽  
Feng Feng Xi ◽  
Shuai Guo
Keyword(s):  
Reaction Force ◽  
Mobile Platform ◽  
Mobile Manipulator ◽  
Work Piece ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
The Third ◽  
First Case ◽  
Coupling Terms ◽  
Inertia Forces

Presented in this chapter is a method for design and analysis of a mobile manipulator. The wrench induced by the movement of the robot arm will cause system tip-over or slip. In tip-over analysis, three cases are considered. The first case deals with the effect of the link weights and tip payload on the horizontal position of the CG. The second case deals with the effect of the joint speeds through the coupling terms including centrifugal forces and gyroscopic moments. The third case deals with the effect of the joint accelerations through the inertia forces and moments. In slip analysis, the first case considers the reaction force in relation to the stand-off distance between system and work-piece. The second and third cases investigate the effects of the joint speeds and accelerations. Then, the mobile platform is optimized to have maximum tip-over stability which optimizes the placement of the robot arm and accessory on the mobile platform. The effectiveness of the proposed method is demonstrated.

A Methodology for tele-operating mobile manipulators with an emphasis on operator ease of use

Robotica ◽  
2012 ◽  
Vol 31 (3) ◽  
pp. 331-344 ◽  
Author(s):  
M. Frejek ◽  
S. B. Nokleby
Keyword(s):  
Degrees Of Freedom ◽  
Ease Of Use ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Test Results ◽  
End Effector ◽  
Optimization Routine ◽  
Singular Configuration ◽  
6 Degrees Of Freedom ◽  
Mobile Base

SUMMARYAn algorithm for the tele-operation of mobile-manipulator systems with a focus on ease of use for the operator is presented. The algorithm allows for unified, intuitive, and coordinated control of mobile manipulators. It consists of three states. In the first state, a single 6-degrees-of-freedom (DOF) joystick is used to control the manipulator's position and orientation. The second state occurs when the manipulator approaches a singular configuration, resulting in the mobile base moving in a manner so as to keep the end-effector travelling in its last direction of motion. This is done through the use of a constrained optimization routine. The third state is entered when the operator returns the joystick to the home position. Both the mobile base and manipulator move with respect to one another keeping the end-effector stationary and placing the manipulator into an ideal configuration. The algorithm has been implemented on an 8-DOF mobile manipulator and the test results show that it is effective at moving the system in an intuitive manner.

scholarly journals Adaptive 3D Visual Servoing of a Scara Robot Manipulator with Unknown Dynamic and Vision System Parameters

Automation ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 127-140
Author(s):  
Jorge Antonio Sarapura ◽  
Flavio Roberti ◽  
Ricardo Carelli
Keyword(s):  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Moving Objects ◽  
Robot Manipulator ◽  
Vision System ◽  
Robot Dynamics ◽  
Complete Control ◽  
Scara Robot ◽  
Dynamic Controller ◽  
Control Scheme

In the present work, we develop an adaptive dynamic controller based on monocular vision for the tracking of objects with a three-degrees of freedom (DOF) Scara robot manipulator. The main characteristic of the proposed control scheme is that it considers the robot dynamics, the depth of the moving object, and the mounting of the fixed camera to be unknown. The design of the control algorithm is based on an adaptive kinematic visual servo controller whose objective is the tracking of moving objects even with uncertainties in the parameters of the camera and its mounting. The design also includes a dynamic controller in cascade with the former one whose objective is to compensate the dynamics of the manipulator by generating the final control actions to the robot even with uncertainties in the parameters of its dynamic model. Using Lyapunov’s theory, we analyze the two proposed adaptive controllers for stability properties, and, through simulations, the performance of the complete control scheme is shown.

scholarly journals Using FPGA Design and HIL Algorithm Simulation to Control Visual Servoing

2018 ◽  
Vol 7 (2) ◽  
pp. 168
Author(s):  
Lway Faisal Abdulrazak ◽  
Zaid A. Aljawary
Keyword(s):  
Object Tracking ◽  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Optimal Solution ◽  
Robot Dynamics ◽  
Fpga Design ◽  
Joint Torques ◽  
Array Technology ◽  
Gate Array ◽  
Set Up

<span lang="EN-US">This is a novel research paper provides an optimal solution for object tracking using visual servoing control system with programmable gate array technology to realize the visual controller. The controller takes in account the robot dynamics to generate the joint torques directly for performing the tasks related to object tracking using visual servoing. Also, the notion of dynamic perceptibility provides the capability of the designed system to track desired objects employing direct visual servoing technique. This idea is assimilated in the suggested controller and realized in the programmable gate array. Additionally, this paper grants an ideal control framework for direct visual servoing robots that incorporates dynamic perceptibility features. With the aim of evaluating the proposed FPGA based architecture, the control algorithm is applied to Hardware-in-the-loop simulation (HIL) set up of three degrees of freedom rigid robotic manipulator with three links. Furthermore, different investigations are performed to demonstrate the behavior of the proposed system when a trajectory adjacent to a singularity is attained.</span>

Firm Standing for Legged Mobile Manipulators

2004 ◽  
Vol 16 (3) ◽  
pp. 312-318
Author(s):  
Takashi Tagawa ◽  
◽  
Yasumichi Aiyama ◽  
Hisashi Osumi ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Human Beings ◽  
Hand Force ◽  
Position And Orientation ◽  
Three Dimensional Space

A mobile manipulator generates external force on its hand when it works, making it unable to conduct work accurately because the robot becomes unstable, unlike human beings, who stand stably despite a large hand force acting on their hands. This uses redundant degrees of freedom (DOF) that freely change the body’s position and orientation even if legs are fixed. We focus on a legged robot as a part of locomotion and propose firm standing using a legged mobile manipulator that tolerates greater hand force while maintaining a stable working position. This report proposes firm standing, analyzes it on a two-dimensional vertical plane and in three-dimensional space, and details experiments that demonstrate its feasibility.

Image-based visual servoing schemes for nonholonomic mobile manipulators

Robotica ◽  
2007 ◽  
Vol 25 (2) ◽  
pp. 131-145 ◽  
Author(s):  
Alessandro De Luca ◽  
Giuseppe Oriolo ◽  
Paolo Robuffo Giordano
Keyword(s):  
Visual Servoing ◽  
Kinematic Model ◽  
Time Derivative ◽  
Interaction Matrix ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Redundancy Resolution ◽  
Task Sequencing ◽  
Fixed Base ◽  
Task Oriented

SUMMARYWe consider the task-oriented modeling of the differential kinematics of nonholonomic mobile manipulators (NMMs). A suitable NMM Jacobian is defined that relates the available input commands to the time derivative of the task variables, and can be used to formulate and solve kinematic control problems. When the NMM is redundant with respect to the given task, we provide an extension of two well-known redundancy resolution methods for fixed-base manipulators (Projected Gradient and Task Priority) and introduce a novel technique (Task Sequencing) aimed at improving performance, e.g., avoiding singularities. The proposed methods are applied then to the specific case of image-based visual servoing, where the NMM image Jacobian combines the interaction matrix and the kinematic model of the mobile manipulator. Comparative numerical results are presented for two case studies.

Object-Based Visual Servoing for Autonomous Mobile Manipulators

2014 ◽  
Vol 11 (03) ◽  
pp. 1450025
Author(s):  
Jonghyun Seo ◽  
Jangmyung Lee
Keyword(s):  
Visual Servoing ◽  
Computing Time ◽  
Critical Factor ◽  
Depth Estimation ◽  
Target Object ◽  
Estimation Accuracy ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Long Distance ◽  
Object Based

This paper proposes an object based vision (O-BV) system to implement visual servoing for autonomous mobile manipulators using two charge-coupled device (CCD) cameras. Conventional stereo vision (C-SV) system estimates the depth based on the disparity between two camera images for the same object. However, the disparity is not an effective cue for a small disparity at a long distance. To resolve this problem, in the proposed O-BV system, the individual camera tracks the object independently, and the angles of the two cameras are used to estimate the distance to the object. This depth estimation technique is applied for an autonomous mobile robot to approach to a target object precisely. The O-BV system is experimentally compared to the C-SV system in terms of computing time and depth estimation accuracy. Also the two cameras which are attached on the top of the autonomous mobile manipulator have been utilized for the mobile manipulator to approach to a target object precisely through the visual servoing. Through the experiments, it is demonstrated that the fast and precise depth estimation is a critical factor for the successful visual servoing.

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