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 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.

Dynamical Sliding Mode Control of Mobile Manipulators

2009 ◽  
Vol 626-627 ◽  
pp. 453-458
Author(s):  
Hong Mei ◽  
Yong Wang
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Convergence Speed ◽  
Mobile Manipulator ◽  
Control Law ◽  
Mobile Manipulators ◽  
Mode Control ◽  
Chattering Effect ◽  
The Given ◽  
Actual Control

A solution to the problem of the elimination of the chattering effect and the improving of the convergence speed for sliding mode control is presented in this paper.A new dynamical sliding mode controller is developed which takes the first derivative of the control signal instead of the actual control as control and results in smoothed control inputs to the given system.A new nonlinear sliding mode surface is devised which can improve the convergence speed in the sliding phase.Exponential reaching law is taken to determine the control law which can improve the convergence speed in the reaching phase.A mobile manipulator with two arms is taken as an example to track a given trajectory with the proposed controller. It is found that the new developed method has a high convergence speed and the chattering is also reduced greatly.

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.

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.

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.

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.

Decentralized Dynamic Control of a Nonholonomic Mobile Manipulator Collective: A Simulation Study

2008 ◽  
Author(s):  
Hao Su ◽  
Venkat Krovi
Keyword(s):  
Control Algorithm ◽  
Null Space ◽  
Dynamic Control ◽  
Mobile Manipulator ◽  
Mobile Manipulators ◽  
Level Control ◽  
Individual Agent ◽  
End Effector ◽  
High Level ◽  
Task Accomplishment

In this paper, we present a decentralized dynamic control algorithm for a robot collective consisting of multiple nonholonomic wheeled mobile manipulators (NH-WMMs) capable of cooperatively transporting a common payload. In this algorithm, the high level controller deals with motion/force control of the payload, at the same time distributes the motion/force task into individual agents by grasp description matrix. In each individual agent, the low level controller decomposes the system dynamics into decoupled task space (end-effector motions/forces) and a dynamically-consistent null-space (internal motions/forces) component. The agent level control algorithm facilitates the prioritized operational task accomplishment with the end-effector impedance-mode controller and secondary null-space control. The scalability and modularity is guaranteed upon the decentralized control architecture. Numerical simulations are performed for a 2-NH-WMM system carrying a payload (with/without uncertainty) to validate this approach.

Human Step Rehabilitation Using a Robot Attached to the Pelvis

2004 ◽  
Author(s):  
D. Aoyagi ◽  
W. E. Inchinose ◽  
D. J. Reinkensmeyer ◽  
J. E. Bobrow
Keyword(s):  
Force Control ◽  
Control Algorithm ◽  
Control Law ◽  
Task Space ◽  
Control Laws ◽  
Position Feedback ◽  
Pelvic Motion ◽  
Linear Force ◽  
And Control ◽  
Piston Chamber

This paper describes a new robot capable of manipulating pelvic motion during human step training on a treadmill. The robot, PAM (Pelvic Assist Manipulator), uses two pneumatically actuated subsystems arranged in a tripod configuration to measure and control the pelvis of a person during body weight supported stepping on a treadmill. The device can be used in a back-drivable mode to record pelvic trajectories, either specified manually by a therapist or pre-recorded from unimpaired subjects, then replay these trajectories using a PD position feedback control law in the task space and a non-linear force control algorithm for each piston chamber. The control laws are presented, along with data that demonstrate the ability of the device to record and replay the pelvic motions that occur during normal walking.

scholarly journals Position/Force Control of Manipulator in Contact with Flexible Environment

2019 ◽  
Vol 13 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Piotr Gierlak
Keyword(s):  
Neural Networks ◽  
Significant Influence ◽  
Contact Surface ◽  
Force Control ◽  
Tracking Control ◽  
Control Algorithm ◽  
Control Law ◽  
Controlled System ◽  
End Effector ◽  
Control Purpose

Abstract The paper presents the issue position/force control of a manipulator in contact with the flexible environment. It consists of the realisation of manipulator end-effector motion on the environment surface with the simultaneous appliance of desired pressure on the surface. The paper considers the case of a flexible environment when its deformation occurs under the pressure, which has a significant influence on the control purpose realisation. The article presents the model of the controlled system and the problem of tracking control with the use of neural networks. The control algorithm includes contact surface flexibility in order to improve control quality. The article presents the results of numerical simulations, which indicate the correctness of the applied control law.

Sign in / Sign up

Export Citation Format

Share Document