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.

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.

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.

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.

Decoupled Task- and Null-Space Dynamic Control of a Redundant Nonholonomic Mobile Manipulator

2006 ◽  
Author(s):  
Glenn D. White ◽  
Venkat N. Krovi
Keyword(s):  
Null Space ◽  
Dynamic Control ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Redundancy Resolution ◽  
Task Space ◽  
Dynamic Interactions ◽  
End Effector ◽  
Internal Motions ◽  
Mobile Base

Our overall goal is to develop semi-autonomous and decentralized task performance capabilities during cooperative payload transport by a fleet of wheeled mobile manipulators (WMM). Each nonholonomic WMM consists of a planar two-link manipulator mounted on top of a differentially-driven wheeled mobile base. The nonholonomic base and the significant inherent redundancy create challenges for control of end-effector motion/force outputs. Nevertheless, realizing this capability is a critical precursor to decentralized payload manipulation operations. To this end, a dynamic redundancy resolution strategy is critical in order to control the dynamic interactions. The system dynamics are decomposed into a task space component (consisting of end-effector motions/forces) and a decoupled dynamically-consistent null-space part (of internal-motions/forces). A task-space controller is developed that allows each WMM module to be able to control its end-effector (motions/forces) interactions with respect to the payload. The surplus of actuation is then used to independently control internal-motions (of the mobile base) as long as they do not conflict with the primary goal. A variety of numerical simulations are then performed to test this capability of the end-effector and mobile base to independently track complex motion/force trajectories.

Dynamic redundancy resolution in a nonholonomic wheeled mobile manipulator

Robotica ◽  
2007 ◽  
Vol 25 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Glenn D. White ◽  
Rajankumar M. Bhatt ◽  
Venkat N. Krovi
Keyword(s):  
Null Space ◽  
Subsequent Development ◽  
Nonholonomic Constraints ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Redundancy Resolution ◽  
Task Space ◽  
End Effector ◽  
Internal Motions ◽  
Fixed Base

SUMMARYWheeled Mobile Manipulators (WMM) possess many advantages over fixed-base counterparts in terms of improved workspace, mobility and robustness. However, the combination of the nonholonomic constraints with the inherent redundancy limits effective exploitation of end-effector payload manipulation capabilities. The dynamic-level redundancy-resolution scheme presented in this paper decomposes the system dynamics into decoupled task-space (end-effector motions/forces) and a dynamically consistent null-space (internal motions/forces) component. This simplifies the subsequent development of a prioritized task-space control (of end-effector interactions) and a decoupled but secondary null-space control (of internal motions) in a hierarchical WMM controller. Various aspects of the ensuing novel capabilities are illustrated using a series of simulation results.

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 A Fuzzy Backstepping Control of a Mobile Manipulator with Torque Limits Avoidance

1970 ◽  
Vol 5 (2) ◽  
pp. 127-133
Author(s):  
Mohamed Boukattaya ◽  
Tarak Damak ◽  
Mohamed Jallouli
Keyword(s):  
Control Algorithm ◽  
Null Space ◽  
Joint Torque ◽  
Mobile Manipulator ◽  
Redundancy Resolution ◽  
Task Space ◽  
End Effector ◽  
Simulation Results ◽  
Pseudo Inverse ◽  
Selection Of

In this paper, we present a dynamic redundancy resolution technique for mobile manipulator subject to joint torque limits. First, the dynamic model of the mobile manipulator in feasible motion space is given. Next, a control algorithm is proposed which completely decouples the motion of the system into the end-effector motion in the task space and an internal motion in the null space and controls them in prioritized basis with priority given to the primary task space and enables the selection of characteristics in both subspaces separately. A special attention is given to the joints torque limits avoidance where a new weighted pseudo-inverse of the Jacobian that accounts for both inertia and torque limits is proposed to solve problems inherent to torque limits of the system. Simulation results are given to illustrate the coordination of two subsystems in executing the desired trajectory without violating the joint torque limits.

Mission Design of Mobile Manipulators in Cluttered Environments for Service Applications

2020 ◽  
pp. 1358-1376
Author(s):  
Elias K. Xidias ◽  
Philip N. Azariadis ◽  
Nikos A. Aspragathos
Keyword(s):  
Inverse Image ◽  
Mission Design ◽  
Mobile Manipulator ◽  
Indoor Environments ◽  
Mobile Manipulators ◽  
Higher Dimension ◽  
End Effector ◽  
Cluttered Environments ◽  
Cost Simulation ◽  
The Given

The purpose of this paper is to present a mission design approach for a service mobile manipulator which is moving and manipulating objects in partly known indoor environments. The mobile manipulator is requested to pick up and place objects on predefined places (stations). The proposed approach is based on the Bump-Surface concept to represent robot's environment through a single mathematical entity. The solution of the mission design problem is searched on a higher dimension Bump-Surface in such a way that its inverse image into the actual robot environment satisfies the given objectives and constraints. The problem's objectives consist of determining the best feasible paths for both the mobile platform and for the manipulator's end-effector so that all the stations are served at the lowest possible cost. Simulation examples are presented to show the effectiveness of the presented approach.

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.

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