scholarly journals Trajectory Tracking Control of Mobile Manipulators Subject to Unknown External Forces

2021 ◽  
Author(s):  
Miroslaw Galicki
Keyword(s):  
Lyapunov Stability Theory ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Trajectory Tracking Control ◽  
Friction Forces ◽  
New Class ◽  
Sliding Manifold ◽  
Reaction Forces ◽  
External Forces ◽  
Sliding Technique

Abstract This work proposes a new class of controllers for mobile manipulators subject to both undesirable forces exerted on the end-effector and slip reaction forces acting on the platform wheels, unknown friction forces coming from joints directly driven by the actuators as well as undesirable forces caused by kinematic singular configurations appearing on the mechanism trajectory. Based on suitably defined task space non-singular terminal sliding manifold (TSM) and the Lyapunov stability theory, we derive a class of estimated extended transposed Jacobian controllers which seem to be effective in counteracting the unstructured forces. Moreover, in order to eliminate (or to alleviate) undesirable chattering effects, the proposed control law involves second order sliding technique. The numerical computations closely related to an experiment, which are carried out for a mobile manipulator consisting of a platform of (2, 0) type and holonomic manipulator of two revolute kinematic pairs, illustrate the performance of the proposed controllers.

Optimal trajectory planning for a redundant mobile manipulator with non-holonomic constraints performing push–pull tasks

Robotica ◽  
2008 ◽  
Vol 26 (3) ◽  
pp. 385-394 ◽  
Author(s):  
José P. Puga ◽  
Luciano E. Chiang
Keyword(s):  
Joint Angle ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Dynamic Effects ◽  
Weighted Function ◽  
Joint Torques ◽  
Holonomic Constraints ◽  
Buried Object ◽  
External Forces ◽  
Optimal Trajectory Planning

SUMMARYThis work presents a method to generate optimal trajectories for redundant mobile manipulators based on a weighted function that considers simultaneously joint torques, manipulability and preferred joint angle references. This method is applicable to a group of tasks, commonly known as push–pull tasks, in which a redundant mobile manipulator subject to non-holonomic constraints moves slowly while exerting a set of forces against the environment. In practice, this occurs when the manipulator is pulling against an object such as when opening a door or unearthing a buried object. Torque is computed in a quasi-static manner, mainly taking into consideration the effect of multiple external forces while neglecting dynamic effects. The formulation incorporates a criterion for optimizing a starting configuration, and special considerations are made to account for non-holonomic constraints. The application to an existing mobile manipulator is described.

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.

Task space control of mobile manipulators

Robotica ◽  
2010 ◽  
Vol 29 (2) ◽  
pp. 221-232 ◽  
Author(s):  
Mirosław Galicki
Keyword(s):  
State Constraints ◽  
Lyapunov Stability Theory ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Minimal Energy ◽  
Task Space ◽  
End Effector ◽  
Task Space Control ◽  
Simulation Results ◽  
Penalty Function Approach

SUMMARYThis study offers the solution of the end-effector trajectory tracking problem subject to state constraints, suitably transformed into control-dependent ones, for mobile manipulators. Based on the Lyapunov stability theory, a class of controllers fulfilling the above constraints and generating the mobile manipulator trajectory with (instantaneous) minimal energy, is proposed. The problem of manipulability enforcement is solved here based on an exterior penalty function approach which results in continuous mobile manipulator controls even near boundaries of state constraints. The numerical simulation results carried out for a mobile manipulator consisting of a non-holonomic unicycle and a holonomic manipulator of two revolute kinematic pairs, operating in a two-dimensional task space, illustrate the performance of the proposed controllers.

Trajectory tracking control in workspace-defined tasks for nonholonomic mobile manipulators

Robotica ◽  
2009 ◽  
Vol 28 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Alicja Mazur
Keyword(s):  
Tracking Control ◽  
Mobile Platform ◽  
Mobile Manipulator ◽  
Regularity Conditions ◽  
Mobile Manipulators ◽  
Input Output ◽  
Trajectory Tracking Control ◽  
Tracking Controllers ◽  
Theoretical Considerations ◽  
Selection Of

SUMMARYThis paper considers a problem of tracking control design for different types of nonholonomic mobile manipulators. The mobile platform is in form of a unicycle. In the first step, an input–output decoupling controller is developed. The proposed selection of output functions is in more general form than the output functions previously introduced by others [Yamamoto and Yun]. It makes possible to move simultaneously, the mobile platform and the manipulator built on it. Regularity conditions that guarantee the existence of the input–output decoupling control law are presented. In the second step, trajectory and path tracking controllers are formulated and presented. Theoretical considerations are illustrated with simulations for the mobile manipulator consisting of a vertical, three degree of freeedom (DOF) pendulum (with holonomic or nonholonomic drives) mounted atop of a unicycle.

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 On path following control of nonholonomic mobile manipulators

2009 ◽  
Vol 19 (4) ◽  
pp. 561-574 ◽  
Author(s):  
Alicja Mazur ◽  
Dawid Szakiel
Keyword(s):  
Control Algorithm ◽  
Dynamic Control ◽  
Path Following ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Control Laws ◽  
Kinematic Control ◽  
Motion Constraints ◽  
Path Following Control ◽  
Cascade Structure

On path following control of nonholonomic mobile manipulatorsThis paper describes the problem of designing control laws for path following robots, including two types of nonholonomic mobile manipulators. Due to a cascade structure of the motion equation, a backstepping procedure is used to achieve motion along a desired path. The control algorithm consists of two simultaneously working controllers: the kinematic controller, solving motion constraints, and the dynamic controller, preserving an appropriate coordination between both subsystems of a mobile manipulator, i.e. the mobile platform and the manipulating arm. A description of the nonholonomic subsystem relative to the desired path using the Frenet parametrization is the basis for formulating the path following problem and designing a kinematic control algorithm. In turn, the dynamic control algorithm is a modification of a passivity-based controller. Theoretical deliberations are illustrated with simulations.

Tip-Over Stability Analysis for a Wheeled Mobile Manipulator

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Shuai Guo ◽  
Tao Song ◽  
Fengfeng (Jeff) Xi ◽  
Richard Phillip Mohamed
Keyword(s):  
Stability Analysis ◽  
Path Planning ◽  
Static Load ◽  
System Stability ◽  
Mobile Manipulator ◽  
Inertial Forces ◽  
Horizontal Position ◽  
Reaction Forces ◽  
Simulation Results

A method is presented for tip-over stability analysis of a wheeled mobile manipulator. A wheeled mobile manipulator may tip over resulting from its operation. In this study, first a Newton–Euler formulation is applied to formulate the manipulator’s reaction forces and moments exerted onto the mobile platform. Tip-over criterion is derived to judge the system stability. Three load and motion analyses are carried on. The first static load deals with links and payload to show the effect of the horizontal position of the system’s center of gravity (CG). The second and third are the inertial forces resulting from joint speeds and accelerations, respectively. Case study is path planning with tip-over criterion result which can make the system stable along the path. The simulation results demonstrate the effectiveness of the proposed method.

Determination of the base position and working area for mobile manipulators

2016 ◽  
Vol 36 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Shunan Ren ◽  
Xiangdong Yang ◽  
Jing Xu ◽  
Guolei Wang ◽  
Ying Xie ◽  
...  
Keyword(s):  
Operation Mode ◽  
Mobile Manipulator ◽  
Planning Problem ◽  
Mobile Manipulators ◽  
Line Planning ◽  
Content Type ◽  
Practical Applications ◽  
Base Position ◽  
Intersection Area ◽  
Intersection Line

Purpose – The purpose of this paper is to determine the base position and the largest working area for mobile manipulators. The base position determines the workspace of the mobile manipulator, particularly when the operation mode is intermittent (i.e. the mobile platform stops when the manipulator conducts the task). When the base of the manipulator is in the intersection area of the Base’s Workable Location Spaces (BWLSes), the end effector (EE) can reach all path points. In this study, the intersection line of BWLSes is calculated numerically, and the largest working area is determined using the BWLS concept. The performance of this method is validated with simulations on specific surface segments, such as plane, cylinder and conical surface segments. Design/methodology/approach – The BWLS is used to determine the largest working area and the base position in which the mobile manipulator can reach all path points with the objective of reducing off-line planning time. Findings – Without considering the orientation of the EE, the base position and the working area for the mobile manipulator are determined using the BWLS. Compared to other methods, the proposed algorithm is beneficial when the planning problem has six dimensions, ensuring the reachability and stability of the EE. Originality/value – The algorithm needs no manual configuration, and its performance is investigated for typical surfaces in practical applications.

Adaptive Integrated Control for Omnidirectional Mobile Manipulators Based on Neural-Network

2011 ◽  
pp. 310-325
Author(s):  
Xiang-min Tan ◽  
Dongbin Zhao ◽  
Jianqiang Yi ◽  
Dong Xu
Keyword(s):  
Neural Network ◽  
Large Scale ◽  
Integrated Control ◽  
External Disturbance ◽  
Torque Control ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Modeling And Control ◽  
Control Approach ◽  
Proposed Model

An omnidirectional mobile manipulator, due to its large-scale mobility and dexterous manipulability, has attracted lots of attention in the last decades. However, modeling and control of such systems are very challenging because of their complicated mechanism. In this paper, an unified dynamic model is developed by Lagrange Formalism. In terms of the proposed model, an adaptive integrated tracking controller, based on the computed torque control (CTC) method and the radial basis function neural-network (RBFNN), is presented subsequently. Although CTC is an effective motion control strategy for mobile manipulators, it requires precise models. To handle the unmodeled dynamics and the external disturbance, a RBFNN, serving as a compensator, is adopted. This proposed controller combines the advantages of CTC and RBFNN. Simulation results show the correctness of the proposed model and the effectiveness of the control approach.

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