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 Position-force control of mobile manipulator – nonadaptive and adaptive case

2017 ◽  
Vol 27 (4) ◽  
pp. 487-503 ◽  
Author(s):  
Mirela Kaczmarek ◽  
Wojciech Domski ◽  
Alicja Mazur
Keyword(s):  
Force Control ◽  
Control Algorithm ◽  
Parametric Uncertainty ◽  
Mobile Manipulator ◽  
Control Law ◽  
Mobile Manipulators ◽  
Constrained Dynamics ◽  
Holonomic Constraint ◽  
System A ◽  
Theoretical Considerations

AbstractThis article presents a control algorithm for nonholonomic mobile manipulators with a simple, geometric holonomic constraint imposed on the robot’s arm. A mathematical model in generalized, auxiliary and linearized coordinates is presented, as well as the constrained dynamics of the robotic system. A position-force control law is proposed, both for the fully known robot’s model, as well as for the model with parametric uncertainty in the dynamics. Theoretical considerations are supported by the results of computer simulations.

scholarly journals Point-to-Point Collision-Free Trajectory Planning for Mobile Manipulators

2016 ◽  
Vol 85 (3-4) ◽  
pp. 523-538 ◽  
Author(s):  
Grzegorz Pajak ◽  
Iwona Pajak
Keyword(s):  
Collision Avoidance ◽  
Trajectory Planning ◽  
Three Dimensional ◽  
Nonholonomic Constraints ◽  
Inequality Constraints ◽  
Mobile Manipulator ◽  
Local Perturbation ◽  
Mobile Manipulators ◽  
State Variables ◽  
Mechanical Constraints

AbstractThe collision-free trajectory planning method subject to control constraints for mobile manipulators is presented. The robot task is to move from the current configuration to a given final position in the workspace. The motions are planned in order to maximise an instantaneous manipulability measure to avoid manipulator singularities. Inequality constraints on state variables i.e. collision avoidance conditions and mechanical constraints are taken into consideration. The collision avoidance is accomplished by local perturbation of the mobile manipulator motion in the obstacles neighbourhood. The fulfilment of mechanical constraints is ensured by using a penalty function approach. The proposed method guarantees satisfying control limitations resulting from capabilities of robot actuators by applying the trajectory scaling approach. Nonholonomic constraints in a Pfaffian form are explicitly incorporated into the control algorithm. A computer example involving a mobile manipulator consisting of nonholonomic platform (2,0) class and 3DOF RPR type holonomic manipulator operating in a three-dimensional task space is also presented.

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.

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.

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.

scholarly journals Motion Planning and Control of an Omnidirectional Mobile Robot in Dynamic Environments

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Mahmood Reza Azizi ◽  
Alireza Rastegarpanah ◽  
Rustam Stolkin
Keyword(s):  
Mobile Robot ◽  
Collision Avoidance ◽  
Motion Control ◽  
Equations Of Motion ◽  
Dynamic Environments ◽  
Discrete State ◽  
Omnidirectional Mobile Robot ◽  
Planning And Control ◽  
Avoidance Strategy ◽  
And Performance

Motion control in dynamic environments is one of the most important problems in using mobile robots in collaboration with humans and other robots. In this paper, the motion control of a four-Mecanum-wheeled omnidirectional mobile robot (OMR) in dynamic environments is studied. The robot’s differential equations of motion are extracted using Kane’s method and converted to discrete state space form. A nonlinear model predictive control (NMPC) strategy is designed based on the derived mathematical model to stabilize the robot in desired positions and orientations. As a main contribution of this work, the velocity obstacles (VO) approach is reformulated to be introduced in the NMPC system to avoid the robot from collision with moving and fixed obstacles online. Considering the robot’s physical restrictions, the parameters and functions used in the designed control system and collision avoidance strategy are determined through stability and performance analysis and some criteria are established for calculating the best values of these parameters. The effectiveness of the proposed controller and collision avoidance strategy is evaluated through a series of computer simulations. The simulation results show that the proposed strategy is efficient in stabilizing the robot in the desired configuration and in avoiding collision with obstacles, even in narrow spaces and with complicated arrangements of obstacles.

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.

An optimal trajectory planning method for path tracking of industrial robots

Robotica ◽  
2018 ◽  
Vol 37 (3) ◽  
pp. 502-520 ◽  
Author(s):  
Xianxi Luo ◽  
Shuhui Li ◽  
Shubo Liu ◽  
Guoquan Liu
Keyword(s):  
Trajectory Planning ◽  
Optimal Trajectory ◽  
Optimal Path ◽  
Path Tracking ◽  
Industrial Robots ◽  
Planning Method ◽  
Coordinate Frame ◽  
Optimization Approach ◽  
Cartesian Coordinate ◽  
Optimal Trajectory Planning

SUMMARYThis paper presents an optimal trajectory planning method for industrial robots. The paper specially focuses on the applications of path tracking. The problem is to plan the trajectory with a specified geometric path, while allowing the position and orientation of the path to be arbitrarily selected within the specific ranges. The special contributions of the paper include (1) an optimal path tracking formulation focusing on the least time and energy consumption without violating the kinematic constraints, (2) a special mechanism to discretize a prescribed path integration for segment interpolation to fulfill the optimization requirements of a task with its constraints, (3) a novel genetic algorithm (GA) optimization approach that transforms a target path to be tracked as a curve with optimal translation and orientation with respect to the world Cartesian coordinate frame, (4) an integration of the interval analysis, piecewise planning and GA algorithm to overcome the challenges for solving the special trajectory planning and path tracking optimization problem. Simulation study shows that it is an insufficient condition to define a trajectory just based on the consideration that each point on the trajectory should be reachable. Simulation results also demonstrate that the optimal trajectory for a path tracking problem can be obtained effectively and efficiently using the proposed method. The proposed method has the properties of broad adaptability, high feasibility and capability to achieve global optimization.

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