An alternative stability proof for “Adaptive type-2 fuzzy estimation of uncertainties in the control of electrically flexible-joint robots”

2018 ◽  
Vol 25 (5) ◽  
pp. 977-983 ◽  
Author(s):  
Alireza Izadbakhsh ◽  
Payam Kheirkhahan
Keyword(s):  
Closed Loop ◽  
Loop System ◽  
Control Input ◽  
Closed Loop System ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Robust Stability Analysis ◽  
The Stability ◽  
Estimation Of Uncertainties

This short note points out an improvement on the robust stability analysis for electrically driven flexible joint robots (EDFJR) given in the 2017 paper by Zirkohi and Fateh, entitled “Adaptive type-2 fuzzy estimation of uncertainties in the control of electrically flexible-joint robots.” In their paper, the authors present an interval Type-2 Adaptive fuzzy control scheme for EDFJR. The nonlinearities associated with actuator input constraints have been also considered in their paper. They discussed the saturated and unsaturated region of the control input separately and neglected the transition state between these regions. Moreover, they did not guarantee the stability of the closed-loop system in the saturated area. In this note, an alternative stability proof is presented that does not require this separation, and which guarantees the stability in a more general framework. The overall closed-loop system is proven to be robust, and bounded-input, bounded-output stable, while the motor/joint position errors are uniformly-ultimately bounded based on the Lyapunov's stability concept.

A Simple Structure for Bilateral Transparent Teleoperation Systems With Time Delay

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Alireza Alfi ◽  
Mohammad Farrokhi
Keyword(s):  
Time Delay ◽  
Closed Loop ◽  
Simple Structure ◽  
Finite Impulse Response ◽  
Structure Design ◽  
Loop System ◽  
Bilateral Teleoperation ◽  
Closed Loop System ◽  
The Stability ◽  
Teleoperation Systems

This paper presents a simple structure design for bilateral teleoperation systems with uncertainties in time delay in communication channel. The goal is to achieve complete transparency and robust stability for the closed-loop system. For transparency, two local controllers are designed for the bilateral teleoperation systems. One local controller is responsible for tracking the master commands, and the other one is in charge of force tracking as well as guaranteeing the stability of the closed-loop system in the presence of uncertainties in time delay. The stability analysis will be shown analytically for two cases: (I) the possibly stability and (II) the intrinsically stability. Moreover, in Case II, in order to generate the proper inputs for the master controller in the presence of uncertainties in time delay, an adaptive finite impulse response (FIR) filter is designed to estimate the time delay. The advantages of the proposed method are threefold: (1) stability of the closed-loop system is guaranteed under some mild conditions, (2) the whole system is transparent, and (3) design of the local controllers is simple. Simulation results show good performance of the proposed method.

Mode Decoupling Controller for Feedback Model Updating

2004 ◽  
Author(s):  
Hunsang Jung ◽  
Youngjin Park ◽  
K. C. Park
Keyword(s):  
Closed Loop ◽  
Model Updating ◽  
Control Method ◽  
Loop System ◽  
Mode Shapes ◽  
Closed Loop System ◽  
Sensitivity Matrix ◽  
Data Set ◽  
Conventional Methods ◽  
The Stability

A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed-loop frequency information for parameter modifications to overcome the problems associated with the conventional methods employing the modal sensitivity matrix. To obtain new modal information from the closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of the closed-loop system. The present paper proposes a mode-decoupling controller that can alter a target mode while guaranteeing the stability of the closed-loop, and that can be constructed by using the measured open-loop, mode shapes. A simulation based on time domain input/output data is performed to evaluate the feasibility of the proposed control method, which is subsequently corroborated via experiments. Experimental data obtained on a beam via the proposed mode-decoupling controller have been applied to estimate thicknesses of a beam. The results show that the proposed approach outperforms conventional methods with a far less number of data set for the estimation of system parameters.

scholarly journals Robust LFC Strategy for Wind Integrated Time-Delay Power System Using EID Compensation

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3223 ◽  
Author(s):  
Liu ◽  
Zhang ◽  
Zou
Keyword(s):  
Time Delay ◽  
Power System ◽  
Closed Loop ◽  
Frequency Control ◽  
Loop System ◽  
Load Frequency Control ◽  
System Stability ◽  
Linear Matrix ◽  
Closed Loop System ◽  
The Stability

This paper presents an active disturbance rejection control (ADRC) technique for load frequency control of a wind integrated power system when communication delays are considered. To improve the stability of frequency control, equivalent input disturbances (EID) compensation is used to eliminate the influence of the load variation. In wind integrated power systems, two area controllers are designed to guarantee the stability of the overall closed-loop system. First, a simplified frequency response model of the wind integrated time-delay power system was established. Then the state-space model of the closed-loop system was built by employing state observers. The system stability conditions and controller parameters can be solved by some linear matrix inequalities (LMIs) forms. Finally, the case studies were tested using MATLAB/SIMULINK software and the simulation results show its robustness and effectiveness to maintain power-system stability.

scholarly journals Probabilistic Control for Uncertain Systems

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Randa Herzallah
Keyword(s):  
Control Algorithm ◽  
Probabilistic Models ◽  
Closed Loop ◽  
Inverse Dynamics ◽  
Loop System ◽  
Model Parameters ◽  
Control Input ◽  
Closed Loop System ◽  
Optimal Control Strategy ◽  
Mixture Density

In this paper a new framework has been applied to the design of controllers which encompasses nonlinearity, hysteresis and arbitrary density functions of forward models and inverse controllers. Using mixture density networks, the probabilistic models of both the forward and inverse dynamics are estimated such that they are dependent on the state and the control input. The optimal control strategy is then derived which minimizes uncertainty of the closed loop system. In the absence of reliable plant models, the proposed control algorithm incorporates uncertainties in model parameters, observations, and latent processes. The local stability of the closed loop system has been established. The efficacy of the control algorithm is demonstrated on two nonlinear stochastic control examples with additive and multiplicative noise.

scholarly journals Computation of time-delay for Delayed Network Controlled Temperature Control System

2021 ◽  
Vol 2070 (1) ◽  
pp. 012102
Author(s):  
V Venkatachalam ◽  
M Ramasubramanian ◽  
M Thirumarimurugan ◽  
D Prabhakaran
Keyword(s):  
Control System ◽  
Stability Analysis ◽  
Temperature Control ◽  
Closed Loop ◽  
Simulation Software ◽  
Loop System ◽  
Temperature Control System ◽  
Closed Loop System ◽  
The Stability ◽  
Time Invariant

Abstract This paper presents an Investigation on the stability of network controlled temperature control system having Time-Invariant feedback delays, by utilizing a direct method for TDS stability analysis. A PI controller based stability analysis for temperature control system with Time invariant feedback loop delay has been constructed in this paper. The stability problem has been formulated based on the transfer function model of the closed loop system with various time delays. For different subsets of the controller parameters, based on the stability criterion’s maximal permissible bound of the network link delay that the closed loop system can accommodate without losing the stability has been computed. The effectiveness of the obtained result was validated on a benchmark temperature control system using MATLAB simulation software.

Adaptive Fuzzy Finite-Time Command-Filtered Backstepping Control of Flexible-Joint Robots

Robotica ◽  
2020 ◽  
pp. 1-20
Author(s):  
Roger Datouo ◽  
Joseph Jean-Baptiste Mvogo Ahanda ◽  
Achille Melingui ◽  
Frédéric Biya-Motto ◽  
Bernard Essimbi Zobo
Keyword(s):  
Finite Time ◽  
Closed Loop ◽  
Computational Cost ◽  
Backstepping Control ◽  
Lyapunov Theory ◽  
Loop System ◽  
Closed Loop System ◽  
Flexible Joint ◽  
Adaptive Fuzzy ◽  
Finite Time Stabilization

SUMMARY The problem of finite-time tracking control for n-link flexible-joint robot manipulators is addressed. An adaptive fuzzy finite-time command-filtered backstepping control scheme is presented to solve the following problems: “explosion of terms” problem, finite-time stabilization of the closed-loop system, and the reduction of computational cost. To this end, new virtual adaptive control signals and new finite-time error compensation mechanism are constructed using inherent properties of robot manipulator systems. Based on the Lyapunov theory, the finite-time stabilization of the closed-loop system is proved. Simulation studies show the effectiveness of the proposed method.

scholarly journals Operational Space Control of a Lightweight Robotic Arm Actuated by Shape Memory Alloy (SMA) Wires

2016 ◽  
Author(s):  
Serket Quintanar-Guzmán ◽  
Somasundar Kannan ◽  
Miguel A. Olivares-Mendez ◽  
Holger Voos
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Closed Loop ◽  
Loop System ◽  
Robotic Arm ◽  
Control Law ◽  
Closed Loop System ◽  
End Effector ◽  
Position Regulation ◽  
The Stability

This paper presents the design and control of a two link lightweight robotic arm using a couple of antagonistic Shape Memory Alloy (SMA) wires as actuators. A nonlinear robust control law for accurate positioning of the end effector of the two-link SMA based robotic arm is developed to handle the hysteresis behavior present in the system. The model presented consists of two subsystems: firstly the SMA wires model and secondly the dynamics of the robotic arm itself. The control objective is to position the robotic arm’s end effector in a given operational plane position. For this regulation problem a sliding mode control law is applied to the hysteretic system. Finally a Lyapunov analysis is applied to the closed-loop system demonstrating the stability of the system under given conditions. The simulation results demonstrate the accurate and fast response of the control law for position regulation. In addition, the stability of the closed-loop system can be corroborated.

Position/force control of robot manipulators using reinforcement learning

2019 ◽  
Vol 46 (2) ◽  
pp. 267-280 ◽  
Author(s):  
Adolfo Perrusquía ◽  
Wen Yu ◽  
Alberto Soria
Keyword(s):  
Reinforcement Learning ◽  
Force Control ◽  
Closed Loop ◽  
Position Error ◽  
Loop System ◽  
Closed Loop System ◽  
Content Type ◽  
Impedance Model ◽  
Impedance Parameters ◽  
The Stability

Purpose The position/force control of the robot needs the parameters of the impedance model and generates the desired position from the contact force in the environment. When the environment is unknown, learning algorithms are needed to estimate both the desired force and the parameters of the impedance model. Design/methodology/approach In this paper, the authors use reinforcement learning to learn only the desired force, then they use proportional-integral-derivative admittance control to generate the desired position. The results of the experiment are presented to verify their approach. Findings The position error is minimized without knowing the environment or the impedance parameters. Another advantage of this simplified position/force control is that the transformation of the Cartesian space to the joint space by inverse kinematics is avoided by the feedback control mechanism. The stability of the closed-loop system is proven. Originality/value The position error is minimized without knowing the environment or the impedance parameters. The stability of the closed-loop system is proven.

scholarly journals Actuator Saturation and Control Design for Buildings Structural Systems with Improved Uncertainty Description

2013 ◽  
Vol 20 (2) ◽  
pp. 297-308 ◽  
Author(s):  
Y.C. Ding ◽  
F.L. Weng ◽  
Z.A. Yu
Keyword(s):  
Closed Loop ◽  
Actuator Saturation ◽  
Input Saturation ◽  
Lyapunov Theory ◽  
Loop System ◽  
Structural Systems ◽  
Control Input ◽  
Closed Loop System ◽  
Parameter Uncertainties ◽  
Earthquake Excitation

The problem of robustly active vibration control for a class of earthquake-excited structural systems with time-delay and saturation in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is concerned in this paper. The objective of the designing controllers is to guarantee the robust stability of the closed-loop system and attenuate the disturbance from earthquake excitation. Firstly, by using the linear combination of some matrices to deal with the system's uncertainties, a new system uncertainties description, namely rank-1 uncertainty description, is presented. Then, by introducing a linear varying parameter, the input saturation model is described as a linear parameter varying model. Furthermore, based on parameter-dependent Lyapunov theory and linear matrix inequality (LMI) technique, the LMIs-based conditions for the closed-loop system to be stable are deduced. By solving those conditions, the controller, considering the actuator saturation, input delay and parameters uncertainties, is obtained. Finally, a three-storey linear building structure under earthquake excitation is considered and simulation results are given to show the effectiveness of the proposed controllers.

scholarly journals Design of Switching Multiobjective Controller: A New Approach

2011 ◽  
Vol 2011 ◽  
pp. 1-12
Author(s):  
Ahmad Fakharian
Keyword(s):  
Closed Loop ◽  
Multiplicative Noise ◽  
Loop System ◽  
Switching System ◽  
Closed Loop System ◽  
New Approach ◽  
Output Feedback Controller ◽  
The Stability ◽  
Fuzzy Supervisor ◽  
Globally Stable

Design of switching / output-feedback controller for discrete-time LTI systems with state-multiplicative noise is considered. The closed loop system achieves a minimum bound on the stochastic performance level, while satisfying the performance. The proposed controller is based on a fuzzy supervisor which manages the combination of two separate and controllers. A convex formulation of the two controllers leads to a structure which benefits from the advantages of both controllers to ensure a good performance in both the transient phase ( controller) and the steady phase ( controller). The stability analysis uses the Lyapunov technique, inspired from switching system theory, to prove that the closed loop system with the proposed controller structure remains globally stable despite the configuration changing.

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