A force observation method for tracking control of flexible-link manipulators

Robotica ◽  
2012 ◽  
Vol 31 (4) ◽  
pp. 669-677 ◽  
Author(s):  
S. Farokh Atashzar ◽  
M. Shahbazi ◽  
H. A. Talebi ◽  
F. Towhidkhah
Keyword(s):  
Tracking Control ◽  
Flexible Manipulator ◽  
Control Technique ◽  
Flexible Link ◽  
Robust Controller ◽  
Estimation Errors ◽  
Control Scheme ◽  
Lyapunov Redesign ◽  
Single Link ◽  
Observation Method

SUMMARYIn this paper, a composite controller is proposed for single-link flexible manipulators exposed to external tip force disturbances. In the proposed scheme, the extended Kalman filter is utilized to observe the environmental forces and the Lyapunov redesign robust controller is applied to control the destabilizing effect of the observation errors in noisy situations. The observed force can be utilized in different applications (such as tele-surgical robotics) in order to eliminate the necessity of additional force sensors. This fact is important for structural miniaturization and cost reduction. The main contributions of this paper are (1) proposing a disturbance observation technique for in-contact flexible link manipulators (note that the challenge of Jacobian singularity is studied as a possible diverging factor of the observation) and (2) proposing the composite robust controller to eliminate the destabilizing effect of estimation errors. The advantages of the proposed control scheme over the conventional techniques are analyzed. Simulation results are given for a single-link flexible manipulator to illustrate the effectiveness of the composite control technique and experimental results are given to validate the performance of the observation method.

Vibration Control of a Flexible Link Manipulator Using an Array of Fiber-Optic Curvature Sensors and Piezoelectric Actuators

2007 ◽  
Author(s):  
Kerem Gurses ◽  
Bradley J. Buckman ◽  
Edward J. Park
Keyword(s):  
Motion Control ◽  
Sensor Array ◽  
Fiber Optic ◽  
Element Model ◽  
Flexible Manipulator ◽  
Flexible Link ◽  
Velocity Feedback ◽  
Lyapunov Approach ◽  
Single Link ◽  
Actuator Control

This paper presents a novel feedback sensing approach for actively suppressing vibrations of a single-link flexible manipulator. Slewing of the flexible link by a rotating hub induces vibrations in the link that persist long after the hub stops rotating. These vibrations are suppressed through a combined scheme of PD-based hub motion control and proposed piezoelectric (PZT) actuator control, which is a composite linear and velocity feedback controller. Lyapunov approach was used to synthesize the controller based on a finite element model of the system. Its realization was possible due to the availability of both linear and angular velocity feedback provided by a unique, commercially-available fiber optic curvature sensor array, called ShapeTape™. It is comprised of an array of fiber optic curvature sensors, laminated on a long, thin ribbon tape, geometrically arranged in such a way that, when it is embedded into the flexible link, the bend and twist of the link’s centerline can be measured. Experimental results show the effectiveness of the proposed approach.

A Robust Trajectory Tracking Control Scheme of Two-Link Flexible Manipulator

2011 ◽  
Vol 328-330 ◽  
pp. 2108-2112
Author(s):  
Jing Shuang Lu ◽  
Chun Mei Du ◽  
Rui Zhou ◽  
Na Li
Keyword(s):  
Trajectory Tracking ◽  
Tracking Control ◽  
Vertical Plane ◽  
Flexible Manipulator ◽  
System Model ◽  
Error Signal ◽  
Dynamics Model ◽  
Trajectory Tracking Control ◽  
Control Scheme ◽  
Simulation Results

A simple dynamics model is established based on the two-link flexible manipulator moving within the vertical plane, and a robust simple control scheme is put forward. The advantages of this scheme are simple and good robustness. Only the error signal is needed when designing the control scheme and the acquirement of control signal does not depend on the system model. The simulation results show that this method has a good robustness and stability.

Fault-Tolerant Formation Tracking Control for Heterogeneous Multiagent Systems with Directed Topology

2021 ◽  
Vol 01 (01) ◽  
pp. 2150001
Author(s):  
Jianye Gong ◽  
Yajie Ma ◽  
Bin Jiang ◽  
Zehui Mao
Keyword(s):  
Tracking Control ◽  
Formation Control ◽  
Control Algorithm ◽  
Fault Tolerant ◽  
Control Technique ◽  
Fault Estimation ◽  
Consensus Control ◽  
Formation Tracking ◽  
Control Scheme ◽  
Aerial Vehicle

In this paper, the adaptive fault-tolerant formation tracking control problem for a set of heterogeneous unmanned aerial vehicle (UAV) and unmanned ground vehicle (UGV) systems with actuator loss of effectiveness faults is investigated. The cooperative fault-tolerant formation control strategy for UAV and UGV collaborative systems is classified into the altitude consensus control scheme for follower UAVs and the position cooperative formation control scheme for all followers. The altitude consensus control algorithm is designed by utilizing backstepping control technique to drive all UAVs to a desired predefined height. Then, based on synchronization formation error information, the position cooperative formation control algorithm is proposed for all followers to reach the expected position and perform the desired formation configuration. The adaptive fault estimation term is adopted in the designed fault-tolerant formation control algorithm to compensate for the actuator loss of effectiveness fault. Finally, a simulation example is proposed to reveal the validity of the designed cooperative formation tracking control scheme.

scholarly journals A composite controller based on nonlinear H_∞ and nonlinear disturbance observer for attitude stabilization of a flying robot

2021 ◽  
Vol 22 (1) ◽  
pp. 270
Author(s):  
Vahid Razmavar ◽  
Heidar Ali Talebi ◽  
Farzaneh Abdollahi
Keyword(s):  
Attitude Control ◽  
Disturbance Observer ◽  
External Disturbance ◽  
Parametric Uncertainty ◽  
Control Technique ◽  
Robust Controller ◽  
Nonlinear Disturbance Observer ◽  
Control Scheme ◽  
Nonlinear Disturbance ◽  
Flying Robot

<span>In this article a novel composite control technique is introduced. We added a nonlinear disturbance observer to a nonlinear H_∞ control to form this composite controller. The quadrotor kinematics and dynamics is formulated using euler angles and parameters. After that, this nonlinear robust controller is developed for this flying robot attitude control for the outdoor conditions. Because under these conditions the flying robot, experiences both external disturbance and parametric uncertainty. Stability analysis is also presented to show the global asymptotical stability using a Lyapunov function. The simulation results showed that the suggested composite controller had a better performance in comparison with a nonlinear H_∞ control scheme.</span>

Tracking control of a flexible-link manipulator using neural networks: experimental results

Robotica ◽  
2002 ◽  
Vol 20 (4) ◽  
pp. 417-427 ◽  
Author(s):  
H.A. Talebi ◽  
K. Khorasani ◽  
R. V. Patel
Keyword(s):  
Neural Network ◽  
Tracking Control ◽  
Dynamic Range ◽  
Experimental Results ◽  
Flexible Manipulator ◽  
System Response ◽  
Position Tracking ◽  
Pd Controller ◽  
Flexible Link ◽  
Tracking Controller

In this paper, the problem of tip position tracking control of a flexible-link manipulator is considered. Two neural network schemes are presented. In the first scheme, the controller is composed of a stabilizing joint PD controller and a neural network tracking controller. The objective is to simultaneously achieve hub-position tracking and control of the elastic deflections at the tip. In the second scheme, tracking control of a point along the arm is considered to avoid difficulties associated with the output feedback control of a non-minimum phase flexible manipulator. A separate neural network is employed for determining an appropriate output to be used for feedback. The controller is also composed of a neural network tracking controller and a stabilizing joint PD controller. Experimental results on a single-link flexible manipulator show that the proposed networks result in significant improvements in the system response with an increase in controller dynamic range despite changes in the desired trajectory.

Vibration control of coupled Duffing oscillators in flexible single-link manipulators

2020 ◽  
pp. 107754632095259
Author(s):  
Jie Huang ◽  
Jinchen Ji
Keyword(s):  
High Speed ◽  
Vibration Suppression ◽  
Control Method ◽  
Negative Impact ◽  
Nonlinear Modeling ◽  
Flexible Manipulator ◽  
Flexible Link ◽  
Structural Nonlinearity ◽  
Single Link ◽  
Coupled Duffing Oscillators

Motion-induced oscillations of the flexible single link and its payload at the tip have negative impact on the anticipated performance of the flexible manipulators and thus should be suppressed to achieve tip positioning accuracy and high-speed operation. Because of the structural flexibility, the dynamics of the flexible manipulator can be described by coupled Duffing oscillators when considering the inherent structural nonlinearity of the flexible link into the dynamic modeling. However, little research has been focused on addressing the dynamic coupling issue in the nonlinear modeling of flexible-link manipulators using coupled Duffing oscillators. This article presents coupled Duffing oscillators for the nonlinear modeling of flexible single-link manipulators and then proposes a control method for suppressing the nonlinear vibrations of the coupled Duffing oscillators. Simulated and experimental results obtained from a flexible single-link manipulator test bench are in good agreement with the proposed nonlinear modeling and also demonstrate the effectiveness of the proposed control techniques for vibration suppression of the flexible manipulator.

A Finite Element Approach for Single-Link Flexible Manipulator

2013 ◽  
Vol 347-350 ◽  
pp. 453-456
Author(s):  
Jing Yuan Shi ◽  
Kai Jun Ji ◽  
Yan Kun Tang ◽  
Kun Yang
Keyword(s):  
Finite Element ◽  
Equations Of Motion ◽  
Energy Approach ◽  
Flexible Manipulator ◽  
Flexible Link ◽  
Finite Element Approach ◽  
Single Link ◽  
Element Approach

Many researchers have studied the dynamics of the single-link flexible manipulator. A finite element approach is used in this study to describe the dynamics of the flexible link. The displacement of any point on the link is described in terms of modal displacements. Energy approach is used to formulate the equations of motion.

Fractional Control of a Single-Link Flexible Manipulator

2005 ◽  
Author(s):  
Vicente Feliu ◽  
Blas M. Vinagre ◽  
Concepcio´n A. Monje
Keyword(s):  
Low Frequency ◽  
Nonlinear Effects ◽  
Flexible Manipulator ◽  
Phase System ◽  
Low Frequency Vibration ◽  
Control Scheme ◽  
Single Link ◽  
The Time Domain ◽  
Tip Mass ◽  
Fractional Controller

A new method to control single-link lightweight flexible manipulators in the presence of changes in the load is proposed in this paper. The overall control scheme consists of three nested control loops. Once the friction and other nonlinear effects have been compensated, the inner loop is designed to give a fast motor response. The middle loop decouples the dynamics of the system, and reduces its transfer function to a double integrator. A fractional-derivative controller is used to shape the outer loop into the form of a fractional-order integrator. The result is a constant-phase system with, in the time domain, step responses exhibiting constant overshoot, independently of variations in the load. Continuous and discrete approximate implementations of the fractional controller are simulated. Comparison of the responses to a step command of the manipulator controlled with the proposed approximations and with the ideal fractional controller showed that the latter could be accurately approximated by standard continuous and discrete controllers of high order preserving the robustness. An interesting feature of this control scheme is that the overshoot is independent of the tip mass. This allows a constant safety zone to be delimited for any given placement task of the arm, independently of the load being carried, thereby making it easier to plan collision avoidance. Simulations also include comparison with standard PD controller, and verification of the assumption of dominant low-frequency vibration mode.

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