Robust position-force control of robot manipulator in contact with linear dynamic environment

Robotica ◽  
2005 ◽  
Vol 23 (6) ◽  
pp. 799-803 ◽  
Author(s):  
Branko Karan
Keyword(s):  
Robot Manipulator ◽  
Dynamic Environment ◽  
Interaction Force ◽  
Robot Dynamics ◽  
Boundary Values ◽  
Interaction Forces ◽  
Simultaneous Control ◽  
Control Scheme ◽  
Constant Coefficients ◽  
Environment Parameters

The paper presents a control scheme for simultaneous control of position and force of robot manipulator in contact with an elastodynamic environment. The control makes the assumption that interaction force between the robot and environment is adequately modeled by a second-order linear model with constant coefficients, and its implementation requires the knowledge of only boundary values of the environment parameters. It is shown that, provided that robot dynamics is exactly modeled, the scheme ensures asymptotic convergence of errors along nominal trajectories characterized by constant prescribed interaction forces and constant prescribed velocities along the contact surface.

scholarly journals Neural Networks-based Adaptive State Feedback Control of Robot Manipulators

2007 ◽  
Vol 2 (4) ◽  
pp. 328 ◽  
Author(s):  
Ghania Debbache ◽  
Abdelhak Bennia ◽  
Noureddine Goléa
Keyword(s):  
Neural Networks ◽  
State Feedback ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
External Disturbance ◽  
Nonlinear Function ◽  
State Feedback Control ◽  
Robot Dynamics ◽  
Robust Controller ◽  
Control Scheme

This paper proposes an adaptive control suitable for motion control of robot manipulators with structured and unstructured uncertainties. In order to design an adaptive robust controller, with the ability to compensate these uncertainties, we use neural networks (NN) that have the capability to approximate any nonlinear function over a compact space. In the proposed control scheme, we need not derive the linear formulation of robot dynamic equation and tune the parameters. To reduce the NNs complexity, we consider the properties of robot dynamics and the decomposition of the uncertainties terms. The proposed controller is robust against uncertainties and external disturbance. The validity of the control scheme is demonstrated by computer simulations on a two-link robot manipulator.

scholarly journals Modeling, force estimation and control of steerable catheters for robot-assisted intra-cardiac navigation

2021 ◽  
Author(s):  
Shahir Hasanzadeh
Keyword(s):  
Contact Force ◽  
Position Control ◽  
Dynamic Environment ◽  
Region Of Interest ◽  
Interaction Force ◽  
Control Area ◽  
Target Tissue ◽  
Force Estimation ◽  
Control Scheme ◽  
Catheter Tip

Intra-cardiac catheterization is an effective procedure for diagnosis and treatment of many cardiac disorders such as arrhythmia. The objective of the catheter manipulation is to accurately position the catheter tip at the target tissue on the endocardium and provide a stable contact force for a specific duration to the region of interest. However, this is a challenging task due to the high flexibility of the catheter, ineffective visualization and dynamic environment of the heart. Additionally, the catheter-tissue interaction force, that the procedure outcome highly depends on, is not known to the interventionalist during the catheterization. This thesis deals with improving the safety and effectiveness of the catheterization by making contributions to two main areas; catheter contact force estimation and automatic force/position control of a robotic catheter system. First, a quasi-static model of the planar catheter that predicts the catheter pose for the given actuation variables and external forces in the plane of catheter motion, is proposed. In the next step, the computational efficiency of the proposed model is utilized to develop an online approach for the estimation of the external force at the tip of a catheter based on the pose measurement. The proposed force estimation approach is also extended to 3D by developing an efficient model of the catheter that is derived by coupling the classical Cosserat rod model with a new model of the pull-wire actuation. Experiments performed using electromagnetic sensors verify the feasibility of the proposed schemes in medical applications. In the control area, a position control scheme for a robotic assisted manipulation system is proposed, using the experimentally obtained inverse kinematics that compensates for the non-smooth dynamics of the distal shaft bending mechanism. Compensation of the backlash behavior of the catheter due to its interaction with the surrounding veins is also incorporated in the control scheme. The proposed position controller is then adopted as the internal loop of a hybrid position/force controller that positions the catheter tip to the target tissue and simultaneously, regulates the contact force to a desired value. The viability of the proposed controllers is then verified through simulations and experiments.

scholarly journals Adaptive 3D Visual Servoing of a Scara Robot Manipulator with Unknown Dynamic and Vision System Parameters

Automation ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 127-140
Author(s):  
Jorge Antonio Sarapura ◽  
Flavio Roberti ◽  
Ricardo Carelli
Keyword(s):  
Visual Servoing ◽  
Degrees Of Freedom ◽  
Moving Objects ◽  
Robot Manipulator ◽  
Vision System ◽  
Robot Dynamics ◽  
Complete Control ◽  
Scara Robot ◽  
Dynamic Controller ◽  
Control Scheme

In the present work, we develop an adaptive dynamic controller based on monocular vision for the tracking of objects with a three-degrees of freedom (DOF) Scara robot manipulator. The main characteristic of the proposed control scheme is that it considers the robot dynamics, the depth of the moving object, and the mounting of the fixed camera to be unknown. The design of the control algorithm is based on an adaptive kinematic visual servo controller whose objective is the tracking of moving objects even with uncertainties in the parameters of the camera and its mounting. The design also includes a dynamic controller in cascade with the former one whose objective is to compensate the dynamics of the manipulator by generating the final control actions to the robot even with uncertainties in the parameters of its dynamic model. Using Lyapunov’s theory, we analyze the two proposed adaptive controllers for stability properties, and, through simulations, the performance of the complete control scheme is shown.

scholarly journals Modeling, force estimation and control of steerable catheters for robot-assisted intra-cardiac navigation

2021 ◽  
Author(s):  
Shahir Hasanzadeh
Keyword(s):  
Contact Force ◽  
Position Control ◽  
Dynamic Environment ◽  
Region Of Interest ◽  
Interaction Force ◽  
Control Area ◽  
Target Tissue ◽  
Force Estimation ◽  
Control Scheme ◽  
Catheter Tip

Intra-cardiac catheterization is an effective procedure for diagnosis and treatment of many cardiac disorders such as arrhythmia. The objective of the catheter manipulation is to accurately position the catheter tip at the target tissue on the endocardium and provide a stable contact force for a specific duration to the region of interest. However, this is a challenging task due to the high flexibility of the catheter, ineffective visualization and dynamic environment of the heart. Additionally, the catheter-tissue interaction force, that the procedure outcome highly depends on, is not known to the interventionalist during the catheterization. This thesis deals with improving the safety and effectiveness of the catheterization by making contributions to two main areas; catheter contact force estimation and automatic force/position control of a robotic catheter system. First, a quasi-static model of the planar catheter that predicts the catheter pose for the given actuation variables and external forces in the plane of catheter motion, is proposed. In the next step, the computational efficiency of the proposed model is utilized to develop an online approach for the estimation of the external force at the tip of a catheter based on the pose measurement. The proposed force estimation approach is also extended to 3D by developing an efficient model of the catheter that is derived by coupling the classical Cosserat rod model with a new model of the pull-wire actuation. Experiments performed using electromagnetic sensors verify the feasibility of the proposed schemes in medical applications. In the control area, a position control scheme for a robotic assisted manipulation system is proposed, using the experimentally obtained inverse kinematics that compensates for the non-smooth dynamics of the distal shaft bending mechanism. Compensation of the backlash behavior of the catheter due to its interaction with the surrounding veins is also incorporated in the control scheme. The proposed position controller is then adopted as the internal loop of a hybrid position/force controller that positions the catheter tip to the target tissue and simultaneously, regulates the contact force to a desired value. The viability of the proposed controllers is then verified through simulations and experiments.

scholarly journals Myoelectric Control Techniques for a Rehabilitation Robot

2011 ◽  
Vol 8 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Alan Smith ◽  
Edward E. Brown
Keyword(s):  
Healthy Subjects ◽  
Sagittal Plane ◽  
Robot Manipulator ◽  
Wrist Joint ◽  
Elbow Flexion ◽  
Myoelectric Control ◽  
Average Error ◽  
Rehabilitation Robot ◽  
Control Scheme ◽  
Central Cord Syndrome

This work examines two different types of myoelectric control schemes for the purpose of rehabilitation robot applications. The first is a commonly used technique based on a Gaussian classifier. It is implemented in real time for healthy subjects in addition to a subject with Central Cord Syndrome (CCS). The myoelectric control scheme is used to control three degrees of freedom (DOF) on a robot manipulator which corresponded to the robot's elbow joint, wrist joint, and gripper. The classes of motion controlled include elbow flexion and extension, wrist pronation and supination, hand grasping and releasing, and rest. Healthy subjects were able to achieve 90% accuracy. Single DOF controllers were first tested on the subject with CCS and he achieved 100%, 96%, and 85% accuracy for the elbow, gripper, and wrist controllers respectively. Secondly, he was able to control the three DOF controller at 68% accuracy. The potential applications for this scheme are rehabilitation and teleoperation. To overcome limitations in the pattern recognition based scheme, a second myoelectric control scheme is also presented which is trained using electromyographic (EMG) data derived from natural reaching motions in the sagittal plane. This second scheme is based on a time delayed neural network (TDNN) which has the ability to control multiple DOF at once. The controller tracked a subject's elbow and shoulder joints in the sagittal plane. Results showed an average error of 19° for the two joints. This myoelectric control scheme has the potential of being used in the development of exoskeleton and orthotic rehabilitation applications.

scholarly journals Trajectory Generation for Mobile Robots in a Dynamic Environment using Nonlinear Model Predictive Control

2021 ◽  
Author(s):  
Jonas Berlin ◽  
Georg Hess ◽  
Anton Karlsson ◽  
William Ljungbergh ◽  
Ze Zhang ◽  
...  
Keyword(s):  
Model Predictive Control ◽  
Long Range ◽  
Predictive Control ◽  
Nonlinear Model ◽  
Trajectory Generation ◽  
Dynamic Environment ◽  
Optimization Method ◽  
Time Frame ◽  
Nonlinear Model Predictive Control ◽  
Robot Dynamics

This paper presents an approach to collision-free, long-range trajectory generation for a mobile robot in an industrial environment with static and dynamic obstacles. For the long range planning a visibility graph together with A* is used to find a collision-free path with respect to the static obstacles. This path is used as a reference path to the trajectory planning algorithm that in addition handles dynamic obstacles while complying with the robot dynamics and constraints. A Nonlinear Model Predictive Control (NMPC) solver generates a collision-free trajectory by staying close the initial path but at the same time obeying all constraints. The NMPC problem is solved efficiently by leveraging the new numerical optimization method Proximal Averaged Newton for Optimal Control (PANOC). The algorithm was evaluated by simulation in various environments and successfully generated feasible trajectories spanning hundreds of meters in a tractable time frame.

A FAT-based adaptive controller for robot manipulators without regressor matrix: theory and experiments

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 205-210 ◽  
Author(s):  
An-Chyau Huang ◽  
Shi-Chang Wu ◽  
Wen-Fa Ting
Keyword(s):  
Function Approximation ◽  
Matrix Theory ◽  
Robot Manipulator ◽  
Nonlinear Differential Equations ◽  
Lyapunov Stability Theory ◽  
Adaptive Controller ◽  
Approximation Technique ◽  
Control Scheme ◽  
Approximation Errors ◽  
Theory And Experiments

In this paper, an adaptive control scheme is proposed for an n-link rigid robot manipulator without using the regressor. The robot is firstly modeled as a set of second-order nonlinear differential equations with the assumption that all of the matrices in that model are unavailable. Since these matrices are time-varying and their variation bounds are not given, traditional adaptive or robust designs do not apply. The function approximation technique (FAT) is used here to represent uncertainties in some finite linear combinations of orthonormal basis. The dynamics of the output tracking can thus be proved to be a stable first order filter driven by function approximation errors. Using the Lyapunov stability theory, a set of update laws is derived to give closed loop stability with proper tracking performance. Experiments are also performed on a 2-D robot to test the efficacy of the proposed scheme.

A hybrid impedance control scheme for underwater welding robots with a passive foundation in the controller domain

SIMULATION ◽  
2017 ◽  
Vol 93 (7) ◽  
pp. 619-630 ◽  
Author(s):  
Sunil Kumar ◽  
Vikas Rastogi ◽  
Pardeep Gupta
Keyword(s):  
Minimum Distance ◽  
Position Control ◽  
Robot Manipulator ◽  
Impedance Control ◽  
Graph Model ◽  
Proportional Integral Derivative ◽  
End Effector ◽  
Flexible Arm ◽  
Control Scheme ◽  
Effective Stability

A hybrid impedance control scheme for the force and position control of an end-effector is presented in this paper. The interaction of the end-effector is controlled using a passive foundation with compensation gain. For obtaining the steady state, a proportional–integral–derivative controller is tuned with an impedance controller. The hybrid impedance controller is implemented on a terrestrial (ground) single-arm robot manipulator. The modeling is done by creating a bond graph model and efficacy is substantiated through simulation results. Further, the hybrid impedance control scheme is applied on a two-link flexible arm underwater robot manipulator for welding applications. Underwater conditions, such as hydrodynamic forces, buoyancy forces, and other disturbances, are considered in the modeling. During interaction, the minimum distance from the virtual wall is maintained. A simulation study is carried out, which reveals some effective stability of the system.

Application of non-linear H∞ control to the Tetrabot robot manipulator

1998 ◽  
Vol 212 (6) ◽  
pp. 459-465 ◽  
Author(s):  
I Postlethwaite ◽  
A Bartoszewicz
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Industrial Robot ◽  
External Disturbances ◽  
Six Degrees Of Freedom ◽  
Control Scheme ◽  
Non Linear ◽  
Modelling Uncertainties ◽  
Real Robot ◽  
Robotic Application

In this paper, an application of a non-linear H∞ control law for an industrial robot manipulator is presented. Control of the manipulator motion is formulated into a non-linear H∞ optimization problem, namely optimal tracking performance in the presence of modelling uncertainties and external disturbances. Analytical solutions for this problem are implemented on a real robot. The robot under consideration is the six-degrees-of-freedom GEC Tetrabot. Investigations are made into the selection of weights for the H∞ controller and it is shown how different selections of weights affect the Tetrabot performance. The authors believe this to be the first robotic application of nonlinear H∞ control. Comparisons of the proposed control strategy with conventional proportional-derivative and proportional-integral-derivative controllers show favourable performance of the Tetrabot under the new non-linear H∞ control scheme.

Neuroadaptive Controller for Physical Interaction With an Omni-Directional Mobile Nurse Assistant Robot

2020 ◽  
Author(s):  
Mohammad N. Saadatzi ◽  
Shamsudeen Abubakar ◽  
Sumit Kumar Das ◽  
M. Hossein Saadatzi ◽  
Dan Popa
Keyword(s):  
Online Learning ◽  
Robot Dynamics ◽  
Physical Interaction ◽  
Nursing Assistant ◽  
Simulation Environment ◽  
Patient Handling ◽  
Safe Patient Handling ◽  
Nurse Assistant ◽  
Control Scheme ◽  
Mobile Base

Abstract Robot-assisted healthcare could help alleviate the shortage of nursing staff in hospitals and is a potential solution to assist with safe patient handling and mobility. In an attempt to off-load some of the physically-demanding tasks and automate mundane duties of overburdened nurses, we have developed the Adaptive Robotic Nursing Assistant (ARNA), which is a custom-built omnidirectional mobile platform with a 6-DoF robotic manipulator and a force sensitive walking handlebar. In this paper, we present a robot-specific neuroadaptive controller (NAC) for ARNA’s mobile base that employs online learning to estimate the robot’s unknown dynamic model and nonlinearities. This control scheme relies on an inner-loop torque controller and features convergence with Lyapunov stability guarantees. The NAC forces the robot to emulate a mechanical system with prescribed admittance characteristics during patient walking exercises and bed moving tasks. The proposed admittance controller is implemented on a model of the robot in a Gazebo-ROS simulation environment, and its effectiveness is investigated in terms of online learning of robot dynamics as well as sensitivity to payload variations.

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