Manipulability-Based Configuration Evaluation of Cooperative Payload Transport by Mobile Robot Collectives

2004 ◽  
Author(s):  
Chin Pei Tang ◽  
Venkat Krovi
Keyword(s):  
Mobile Robot ◽  
Single Agent ◽  
System Level ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Cooperative System ◽  
Kinematic Modeling ◽  
Relative Configuration ◽  
Holonomic Constraints ◽  
Kinematic Loops

Interest in cooperative systems typically arises when certain tasks are either too complex to be performed by a single agent or when there are distinct benefits that accrue by cooperation of many simple agents. A quantitative examination of performance enhancement, due to the implementation of cooperation, is critical. In this paper, we focus on the development of a quantitative performance-analysis framework for a cooperative system with multiple wheeled mobile manipulators physically transporting a common payload. Each mobile manipulator module consists of a differentially-driven wheeled mobile robot with a mounted planar three-degree-of-freedom (d.o.f.) manipulator. A composite cooperative system is formed when a payload is placed at the end-effectors of multiple such modules. Such a system possesses the ability to change its relative configuration as well as accommodate relative positioning errors of the mobile bases. However, the combination of nonholonomic constraints due to the mobile bases, holonomic constraints due to the closed kinematic loops formed and the varying actuation of the joints within the cooperative system requires careful treatment for realizing the payload transport task. In this paper, we will analyze the cooperative composite system within a constrained mechanical system framework, by extending methods developed for treatment of articulated-closed-chain systems. Specifically, we will focus on the velocity-level kinematic modeling, while taking into account the nonholonomic/holonomic constraints and different joint-actuation schemes within the system. We then examine the applicability of a manipulability measure (isotropy index), to quantitatively analyze the system-level performance of the cooperative system, with these different joint-actuation schemes, with representative case-studies.

Manipulability-based configuration evaluation of cooperative payload transport by mobile manipulator collectives

Robotica ◽  
2006 ◽  
Vol 25 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Chin Pei Tang ◽  
Venkat N. Krovi
Keyword(s):  
Kinematic Model ◽  
Nonholonomic Constraints ◽  
System Level ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Cooperative System ◽  
Relative Configuration ◽  
Positioning Errors ◽  
Kinematic Loops ◽  
End Effectors

In this paper, we focus on the development of a quantitative performance analysis framework for a cooperative system of multiple wheeled mobile manipulators physically transporting a common payload. Each mobile manipulator module consists of a differentially driven wheeled mobile robot (WMR) with a mounted planar three-degree-of-freedom (DOF) revolute-jointed manipulator. A composite cooperative system is formed when a payload is placed at the end-effectors of many such modules. The system possesses the ability to change its relative configuration as well as to accommodate relative positioning errors of the wheeled agents. However, the combination of nonholonomic constraints due to the mobile bases, holonomic constraints due to the closed kinematic loops, and the different joint-actuation schema (active/passive/locked) within the system requires careful quantitative evaluation to efficiently realize the payload manipulation task. Hence, in this paper, we extend the differential kinematic model for treatment of constrained articulated mechanical systems to formulate a framework to include both the mixture effect of holonomic/nonholonomic constraints and the different possible joint-actuation schema in our system. The system-level performance is then examined quantitatively by the manipulability measure in terms of isotropy index with representative case studies.

A Screw-Theoretic Analysis Framework for Payload Manipulation by Mobile Manipulator Collectives

2005 ◽  
Author(s):  
Rajankumar Bhatt ◽  
Chin Pei Tang ◽  
Michel Abou-Samah ◽  
Venkat Krovi
Keyword(s):  
System Performance ◽  
Single Agent ◽  
Physical Nature ◽  
Theoretical Background ◽  
System Level ◽  
Mobile Manipulator ◽  
Test Bed ◽  
Tight Coupling ◽  
Constrained Mechanical Systems ◽  
The Individual

In recent times, there has been considerable interest in creating and deploying modular cooperating collectives of robots. Interest in such cooperative systems typically arises when certain tasks are either too complex to be performed by a single agent or when there are distinct benefits that accrue by cooperation of many simple robotic modules. However, the nature of the both the individual modules as well as their interactions can affect the overall system performance. In this paper, we examine this aspect in the context of cooperative payload transport by robot collectives wherein the physical nature of the interactions between the various modules creates a tight coupling within the system. We leverage the rich theoretical background of analysis of constrained mechanical systems to provide a systematic framework for formulation and evaluation of system-level performance on the basis of the individual-module characteristics. The composite multi-d.o.f wheeled vehicle, formed by supporting a common payload on the end-effectors of multiple individual mobile manipulator modules, is treated as an in-parallel system with articulated serial-chain arms. The system-level model, constructed from the twist- and wrench-based models of the attached serial chains, can then be systematically analyzed for performance (in terms of mobility and disturbance rejection.) A 2-module composite system example is used through the paper to highlight various aspects of the systematic system model formulation, effects of selection of the actuation at the articulations (active, passive or locked) on system performance and experimental validation on a hardware prototype test bed.

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.

scholarly journals Reactive Self-Collision Avoidance for a Differentially Driven Mobile Manipulator

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 890
Author(s):  
Keunwoo Jang ◽  
Sanghyun Kim ◽  
Jaeheung Park
Keyword(s):  
Mobile Robot ◽  
Collision Avoidance ◽  
Mobile Manipulator ◽  
Distinct Advantage ◽  
Coordinate Frame ◽  
Avoidance Task ◽  
Mobile Manipulators ◽  
Holonomic Constraint ◽  
Buffer Region ◽  
Cartesian Coordinate

This paper introduces a reactive self-collision avoidance algorithm for differentially driven mobile manipulators. The proposed method mainly focuses on self-collision between a manipulator and the mobile robot. We introduce the concept of a distance buffer border (DBB), which is a 3D curved surface enclosing a buffer region of the mobile robot. The region has the thickness equal to buffer distance. When the distance between the manipulator and mobile robot is less than the buffer distance, which means the manipulator lies inside the buffer region of the mobile robot, the proposed strategy is to move the mobile robot away from the manipulator in order for the manipulator to be placed outside the border of the region, the DBB. The strategy is achieved by exerting force on the mobile robot. Therefore, the manipulator can avoid self-collision with the mobile robot without modifying the predefined motion of the manipulator in a world Cartesian coordinate frame. In particular, the direction of the force is determined by considering the non-holonomic constraint of the differentially driven mobile robot. Additionally, the reachability of the manipulator is considered to arrive at a configuration in which the manipulator can be more maneuverable. In this respect, the proposed algorithm has a distinct advantage over existing avoidance methods that do not consider the non-holonomic constraint of the mobile robot and push links away from each other without considering the workspace. To realize the desired force and resulting torque, an avoidance task is constructed by converting them into the accelerations of the mobile robot. The avoidance task is smoothly inserted with a top priority into the controller based on hierarchical quadratic programming. The proposed algorithm was implemented on a differentially driven mobile robot with a 7-DOFs robotic arm and its performance was demonstrated in various experimental scenarios.

scholarly journals Mobile Robots and Cobots Integration: A Preliminary Design of a Mechatronic Interface by Using MBSE Approach

2022 ◽  
Vol 12 (1) ◽  
pp. 419
Author(s):  
Ferdinando Vitolo ◽  
Andrea Rega ◽  
Castrese Di Marino ◽  
Agnese Pasquariello ◽  
Alessandro Zanella ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
System Development ◽  
Industrial Applications ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Domain Modeling ◽  
Safety Level ◽  
Robot Systems ◽  
And Control

Enabling technologies that drive Industry 4.0 and smart factories are pushing in new equipment and system development also to prevent human workers from repetitive and non-ergonomic tasks inside manufacturing plants. One of these tasks is the order-picking which consists in collecting parts from the warehouse and distributing them among the workstations and vice-versa. That task can be completely performed by a Mobile Manipulator that is composed by an industrial manipulator assembled on a Mobile Robot. Although the Mobile Manipulators implementation brings advantages to industrial applications, they are still not widely used due to the lack of dedicated standards on control and safety. Furthermore, there are few integrated solutions and no specific or reference point allowing the safe integration of mobile robots and cobots (already owned by company). This work faces the integration of a generic mobile robot and collaborative robot selected from an identified set of both systems. The paper presents a safe and flexible mechatronic interface developed by using MBSE principles, multi-domain modeling, and adopting preliminary assumptions on the hardware and software synchronization level of both involved systems. The interface enables the re-using of owned robot systems differently from their native tasks. Furthermore, it provides an additional and redundant safety level by enabling power and force limiting both during cobot positioning and control system faulting.

Decentralized Kinematic Control of a Cooperating System of Mobile Manipulators

2002 ◽  
Author(s):  
Michel Abou-Samah ◽  
Venkat Krovi
Keyword(s):  
Degree Of Freedom ◽  
Modular System ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Relative Positioning ◽  
Mobile Platforms ◽  
Relative Configuration ◽  
Kinematic Control ◽  
Common Object ◽  
Positioning Errors

In this paper, we examine the development of a decentralized control framework for a modular system of wheeled mobile manipulators that can team up to cooperatively transport a large common object. Each individually autonomous mobile manipulator consists of a differentially-driven wheeled mobile robot (WMR) with a passive, two-degree-of-freedom, planar, revolute-jointed arm mounted in the plane parallel to the base of the WMR. The composite multi-degree-of-freedom vehicle, formed by placing a common object on the end-effector of two (or more) such mobile manipulator systems, possesses the ability to accommodate relative positioning errors of the mobile bases as well as change its relative configuration. Particular attention is paid for the development of kinematic control schemes for mobile manipulators, which take into account the non-holonomic constraints of the base and the presence of passive joints in the manipulator system. The control scheme developed for the individual mobile manipulators is then adapted for the decentralized kinematic control of two mobile manipulators carrying a common object along a desired trajectory. Experimental evaluation of the performance of the resulting approach and the ability of the overall collaborating system to accommodate, detect and correct for relative positioning errors between the mobile platforms is also presented.

Avoidance Ability of Redundant Mobile Manipulators During Hand Trajectory Tracking

2007 ◽  
Vol 11 (2) ◽  
pp. 135-141
Author(s):  
Mamoru Minami ◽  
◽  
Hiroshi Tanaka ◽  
Yasushi Mae ◽  
Keyword(s):  
Mobile Robot ◽  
Obstacle Avoidance ◽  
Trajectory Tracking ◽  
Shape Index ◽  
Mobile Manipulator ◽  
Redundant Manipulators ◽  
Mobile Manipulators ◽  
Redundant Manipulator ◽  
Configuration Control ◽  
Control Study

We propose a criterion of obstacle avoidance for a mobile manipulator, consisting of a redundant manipulator and a mobile robot. In the configuration control study of redundant manipulators, the avoidance manipulability ellipsoid and the avoidance manipulability shape index have been suggested as an index to symbolize avoidance ability of the manipulator’s shape when the hand tracks a desired trajectory. In following proposed criteria of obstacle avoidance ability, we extend concepts for mobile manipulators to discuss the avoidance ability of intermediate links for mobile operations. We start by analytically formulating, the avoidance manipulability ellipsoid and the avoidance manipulability shape index of a mobile manipulator. We then evaluate the avoidance manipulability shape index representing shape changeability for the entire manipulator’s configuration using a mobile manipulator with a three-link arm as an example.

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.

Lagrangian D’Alembert Modeled Maneuverable Autonomous Non-Holonomic Mobile Robot Using a Closed Loop PD Controller

2009 ◽  
Author(s):  
E. Georgiou ◽  
J. Dai
Keyword(s):  
Mobile Robot ◽  
Closed Loop ◽  
Ad Hoc ◽  
Search And Rescue ◽  
Pd Controller ◽  
Modeling And Control ◽  
Holonomic Constraints ◽  
And Control ◽  
Holonomic Mobile Robot ◽  
Initial Results

The motivation for this work is to develop a platform for a self-localization device. Such a platform has many applications for the autonomous maneuverable non-holonomic mobile robot classification, which can be used for search and rescue or for inspection devices where the robot has a desired path to follow but because of an unknown terrain, the device requires the ability to make ad-hoc corrections to its movement to reach its desire path. The mobile robot is modeled using Lagrangian d’Alembert’s principle considering all the possible inertias and forces generated, and are controlled by restraining movement based on the holonomic and non-holonomic constraints of the modeled vehicle. The device is controlled by a PD controller based on the vehicle’s holonomic and non-holonomic constraints. An experiment was setup to verify the modeling and control structure’s functionality and the initial results are promising.

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