scholarly journals A New Kinematic Model and Control Strategy for a Mobile Platform for Transporting Lightweight Manipulators

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 441
Author(s):  
Daniel Feliu-Talegon ◽  
Andres San-Millan ◽  
Vicente Feliu-Batlle
Keyword(s):  
Control Strategy ◽  
Mechanical Design ◽  
Kinematic Model ◽  
Mobile Platform ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
The Real ◽  
And Control ◽  
Mobile Base

This work is concerned with the mechanical design and the description of the different components of a new mobile base for a lightweight mobile manipulator. These kinds of mobile manipulators are normally composed of multiple lightweight links mounted on a mobile platform. This work is focused on the description of the mobile platform, the development of a new kinematic model and the design of a control strategy for the system. The proposed kinematic model and control strategy are validated by means of experimentation using the real prototype. The workspace of the system is also defined.

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.

Mechanical Design of the Jasper Mobile Manipulator

2008 ◽  
Author(s):  
Darrin Willis ◽  
Scott B. Nokleby ◽  
Remon Pop-Iliev
Keyword(s):  
Robot Manipulator ◽  
Mechanical Design ◽  
Degree Of Freedom ◽  
Mobile Manipulator ◽  
Design Features ◽  
Coupling Device ◽  
Mobile Base

This paper describes the mechanical design and analysis of a mobile-manipulator system comprised of a robot manipulator and a mobile base. The combination of the two is known as a mobile manipulator and combines the maneuverability of the mobile base with the accuracy of the robot manipulator. The mechanical design of a new mobile-manipulator system with the robot manipulator mounted on the front is discussed. The device features an innovative 2-DOF (degree-of-freedom) parallelogram coupling device that allows the base of the robot manipulator to translate vertically and roll longitudinally relative to the mobile base. The coupling device has dampers to reduce the vibrations caused by the motion of the mobile base on the robot manipulator and vice versa. The design features the use of omni-wheels that eliminate the problems inherent with traditional caster wheels.

Toward the Development of Knee Prostheses: Review of Current Active Devices

2019 ◽  
Vol 71 (3) ◽  
Author(s):  
Rafael R. Torrealba ◽  
Edgar D. Fonseca-Rojas
Keyword(s):  
Clinical Assessment ◽  
Control Strategy ◽  
Selection Criteria ◽  
Performance Metrics ◽  
Mechanical Design ◽  
Knee Prostheses ◽  
Active Devices ◽  
Scientific Papers ◽  
Transfemoral Amputees ◽  
And Control

This paper presents a thorough review of the initiatives carried out in the last 10 years toward the development of active knee prostheses (AKP) for transfemoral amputees. Three selection criteria were employed to filter the works to be considered in the review: (1) a prototype of the prosthesis is available; (2) the mechanical design, instrumentation, and control strategy of such a prototype have been presented in a scientific disclosure media; and (3) the prototype has been subjected to clinical assessment at least in a preliminary way. After applying such criteria, 16 projects were selected and further reviewed through a total of 31 scientific papers, considering the following six aspects: (1) actuators, (2) instrumentation, (3) control, (4) testing trials, (5) performance metrics, and (6) limitations. Then, in addition, the chronological appearance of the aforesaid papers is also shown and quantified regarding each of the previously mentioned issues, to initiate discussion on the related topics. Thus, the present review results in a specialized summary of all these developments in a structured format, offering additional understanding of the recent advances achieved in this field.

scholarly journals Mechanical Design and Kinematic Modeling of a Cable-Driven Arm Exoskeleton Incorporating Inaccurate Human Limb Anthropomorphic Parameters

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4461 ◽  
Author(s):  
Weihai Chen ◽  
Zhongyi Li ◽  
Xiang Cui ◽  
Jianbin Zhang ◽  
Shaoping Bai
Keyword(s):  
Mechanical Design ◽  
Kinematic Model ◽  
Light Weight ◽  
Skeletal System ◽  
Kinematic Modeling ◽  
Modeling And Control ◽  
Arm Rehabilitation ◽  
Human Arm ◽  
Human Limb ◽  
And Control

Compared with conventional exoskeletons with rigid links, cable-driven upper-limb exoskeletons are light weight and have simple structures. However, cable-driven exoskeletons rely heavily on the human skeletal system for support. Kinematic modeling and control thus becomes very challenging due to inaccurate anthropomorphic parameters and flexible attachments. In this paper, the mechanical design of a cable-driven arm rehabilitation exoskeleton is proposed to accommodate human limbs of different sizes and shapes. A novel arm cuff able to adapt to the contours of human upper limbs is designed. This has given rise to an exoskeleton which reduces the uncertainties caused by instabilities between the exoskeleton and the human arm. A kinematic model of the exoskeleton is further developed by considering the inaccuracies of human-arm skeleton kinematics and attachment errors of the exoskeleton. A parameter identification method is used to improve the accuracy of the kinematic model. The developed kinematic model is finally tested with a primary experiment with an exoskeleton prototype.

scholarly journals Planning of Collision-Free Trajectory for Mobile Manipulators

2013 ◽  
Vol 18 (2) ◽  
pp. 475-489
Author(s):  
G. Pająk
Keyword(s):  
Mobile Manipulator ◽  
Reference Trajectory ◽  
Mobile Manipulators ◽  
Redundancy Resolution ◽  
Task Space ◽  
End Effector ◽  
Acceleration Level ◽  
Manipulability Measure ◽  
And Control ◽  
Penalty Function Approach

A method of planning sub-optimal trajectory for a mobile manipulator working in the environment including obstacles is presented. The path of the end-effector is defined as a curve that can be parameterized by any scaling parameter, the reference trajectory of a mobile platform is not needed. Constraints connected with the existence of mechanical limits for a given manipulator configuration, collision avoidance conditions and control constraints are considered. The motion of the mobile manipulator is planned in order to maximize the manipulability measure, thus to avoid manipulator singularities. The method is based on a penalty function approach and a redundancy resolution at the acceleration level. A computer example involving a mobile manipulator consisting of a nonholonomic platform and a SCARA type holonomic manipulator operating in a two-dimensional task space is also presented.

Sub-optimal trajectory planning for mobile manipulators

Robotica ◽  
2014 ◽  
Vol 33 (6) ◽  
pp. 1181-1200 ◽  
Author(s):  
Grzegorz Pajak ◽  
Iwona Pajak
Keyword(s):  
Optimal Trajectory ◽  
Control Algorithm ◽  
Nonholonomic Constraints ◽  
Mobile Manipulator ◽  
Reference Trajectory ◽  
Mobile Manipulators ◽  
Control Constraints ◽  
Manipulability Measure ◽  
And Control ◽  
Optimal Trajectory Planning

SUMMARYThis paper presents a method of planning a sub-optimal trajectory for a mobile manipulator subject to mechanical and control constraints. The path of the end-effector is defined as a curve that can be parameterised by any scaling parameter—the reference trajectory of a mobile platform is not needed. Constraints connected with the existence of mechanical limits for a given manipulator configuration, collision avoidance conditions and control constraints are considered. Nonholonomic constraints in a Pfaffian form are explicitly incorporated to the control algorithm. To avoid manipulator singularities, the motion of the robot is planned in order to maximise the manipulability measure.

scholarly journals Collision-Free Trajectory Planning for Mobile Manipulators Subject to Control Constraints

2014 ◽  
Vol 61 (1) ◽  
pp. 35-55
Author(s):  
Grzegorz Pajak ◽  
Iwona Pajak
Keyword(s):  
Three Dimensional ◽  
Nonholonomic Constraints ◽  
Mobile Manipulator ◽  
Reference Trajectory ◽  
Mobile Manipulators ◽  
Control Constraints ◽  
Redundancy Resolution ◽  
Manipulability Measure ◽  
Point To Point ◽  
And Control

Abstract A method of planning collision-free trajectory for a mobile manipulator tracking a line section path is presented. The reference trajectory of a mobile platform is not needed, mechanical and control constraints are taken into account. The method is based on a penalty function approach and a redundancy resolution at the acceleration level. Nonholonomic constraints in a Pfaffian form are explicitly incorporated to the control algorithm. The problem is shown to be equivalent to some point-to-point control problem whose solution may be easier determined. The motion of the mobile manipulator is planned in order to maximise the manipulability measure, thus to avoid manipulator singularities. A computer example involving a mobile manipulator consisting of a nonholonomic platform (2,0) class and a 3 DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.

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.

Trajectory Tracking and Stability Analysis for Mobile Manipulators Based on Decentralized Control

Robotica ◽  
2019 ◽  
Vol 37 (10) ◽  
pp. 1732-1749 ◽  
Author(s):  
Raouf Fareh ◽  
Mohamad R. Saad ◽  
Maarouf Saad ◽  
Abdelkrim Brahmi ◽  
Maamar Bettayeb
Keyword(s):  
Decentralized Control ◽  
Trajectory Tracking ◽  
Lyapunov Stability Theory ◽  
Joint Space ◽  
Mobile Platform ◽  
Mobile Manipulator ◽  
Control Law ◽  
Mobile Manipulators ◽  
Tracking Errors ◽  
Computed Torque

SummaryTrajectory tracking of a mobile manipulator in the Cartesian space based on decentralized control is considered in this paper. The dynamic model is first rearranged to take the form of two interconnected subsystems with constraint flow, namely, a nonholonomic mobile platform subsystem and a holonomic manipulator subsystem. Secondly, using the inverse kinematics, the workspace desired trajectory of the mobile manipulator is transformed to the manipulator joint space as well as the platform desired trajectory. The kinematic control is developed from the desired trajectory of the platform. Then, the desired velocity is derived using the kinematic controller of the mobile platform, after which the velocity is used to obtain the control law of the mobile platform subsystem. Thirdly, the control law of the manipulator subsystem is developed based on the desired and real values of the manipulator, as well as the desired velocity. According to the Lyapunov stability theory, the proposed decentralized control strategy guarantees the global stability of the closed-loop system, and the tracking errors are bounded. Experimental results obtained on a 3-DOF manipulator mounted on a mobile platform are given to demonstrate the feasibility and effectiveness of the proposed approach. This is confirmed by a comparison with the computed torque approach.

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.

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