Operator-based Robust Nonlinear Control Research Articles

Nonlinear Fault-Tolerant Vibration Control for Partial Actuator Fault of a Flexible Arm

This paper presents a nonlinear fault-tolerant vibration control system for a flexible arm, considering partial actuator fault. A lightweight flexible arm with lower stiffness will inevitably cause vibration which will impair the performance of the high-precision control system. Therefore, an operator-based robust nonlinear vibration control system is integrated by a double-sided interactive controller actuated by the Shape Memory Alloy (SMA) actuators for the flexible arm. Furthermore, to improve the safety and reliability of the safety-critical application, fault-tolerant dynamics for partial actuator fault are considered as an essential part of the proposed control system. The experimental cases are set to the partial actuator as faulty conditions, and the proposed vibration control scheme has fault-tolerant dynamics which can still effectively stabilize the vibration displacement. The reconfigurable controller improves the fault-tolerant performance by shortening the vibration time and reducing the vibration displacement of the flexible arm. In addition, compared with a PD controller, the proposed nonlinear vibration control has better performance than the traditional controller. The experimental results show that the effectiveness of the proposed method is confirmed. That is, the safety and reliability of the proposed fault-tolerant vibration control are verified even if in the presence of an actuator fault.

Experimental Study on Support Vector Machine-Based Early Detection for Sensor Faults and Operator-Based Robust Fault Tolerant Control

Considering sensor faults for a thermoelectric cooler actuated by Peltier devices, this work proposes an operator-based robust nonlinear fault tolerant controller (FTC) integrated with early fault detection using a support vector machine (SVM). Firstly, a physical model is formulated based on the law of heat transfer, and the estimated model is derived based on Volterra identification. Then, an operator-based robust nonlinear control system is employed to compensate for uncertainties and to eliminate the effects of coupling. Furthermore, FTC integrated with SVM-based early fault detection is designed to improve the safety performance in the case of sensor faults. The simulation results indicate that SVM-based fault detection can shorten the detection time in comparison to the conventional method without the SVM classier. The experiment results are utilized to verify the tracking performance of the proposed FTC method in the case study.

Multi-objective optimisation for operator-based robust nonlinear control design for wireless power transfer systems

Multi-objective optimisation for operator-based robust nonlinear control design for wireless power transfer systems

Multi-objective optimisation for operator-based robust nonlinear control design for wireless power transfer systems

Multi-objective optimisation for operator-based robust nonlinear control design for wireless power transfer systems

Operator-based robust nonlinear free vibration control of a flexible plate with unknown input nonlinearity

In this paper, a robust nonlinear free vibration control design using an operator based robust right coprime factorization approach is considered for a flexible plate with unknown input nonlinearity. With considering the effect of unknown input nonlinearity from the piezoelectric actuator, operator based controllers are designed to guarantee the robust stability of the nonlinear free vibration control system. Simultaneously, for ensuring the desired tracking performance and reducing the effect of unknown input nonlinearity, operator based tracking compensator and estimation structure are given, respectively. Finally, both simulation and experimental results are shown to verify the effectiveness of the proposed control scheme.

Operator-Based Robust Nonlinear Control Analysis and Design for a Bio-Inspired Robot Arm with Measurement Uncertainties

In this paper, a robust nonlinear tracking control design for a bio-inspired robot arm with human-like motion mechanism is investigated, and the bio-inspired operator controller based on human multi-joint viscoelastic properties is designed by using operator-based robust right coprime factorization approach. The motion mechanism of human multi-joint arm is used, and the measurement uncertainties of human multi-joint arm viscoelasticity are considered in designing bio-inspired operator controller. Based on the proposed design scheme, the sufficient conditions for the robust stability are derived in considering the coupling effects and measurement uncertainties, and the output tracking performance is realized. The effectiveness of the proposed design scheme was confirmed by the simulation results based on experimental data, and the time-varying estimated experimental data of human multi-joint arm viscoelasticity is used in simulation.

Operator-based robust nonlinear control for SISO and MIMO nonlinear systems with PI hysteresis

In this paper, operator based robust nonlinear control for single-input single-output U+0028 SISO U+0029 and multi-input multi-output U+0028 MIMO U+0029 nonlinear uncertain systems preceded by generalized Prandtl-Ishlinskii U+0028 PI U+0029 hysteresis is considered respectively. In detail, by using operator based robust right coprime factorization approach, the control system design structures including feedforward and feedback controllers for both SISO and MIMO nonlinear uncertain systems are given, respectively. In which, the controller design includes the information of PI hysteresis and its inverse, and some sufficient conditions for the controllers in both SISO and MIMO systems should be satisfied are also derived respectively. Based on the proposed conditions, influence from hysteresis is rejected, the systems are robustly stable and output tracking performance can be realized. Finally, the effectiveness of the proposed method is confirmed by numerical simulations.

Experimental study on operator-based robust nonlinear vibration control for an L-shaped arm with unknown load

A linear-motor-driven L-shaped arm experimental system is studied in this article. The arm with unknown load is driven by the motor and actuated by a piezoelectric actuator at the same time. This study aims to control the motor motion and the actuator’s behavior simultaneously, resulting in less arm vibration. First, the arm vibration relating to the load and the linear motor is modeled by considering it as an Euler–Bernoulli beam. Then, the control design for the arm and motor is proposed using the operator-based nonlinear control approach involving an on-line discrete wavelet transform. The operator-based right coprime factorization is used to ensure the system stable and robust. The discrete wavelet transform is utilized to remove the influences of some undesired disturbances and improve the operator-based control performance. In addition, the load mass is estimated using fast Fourier transform based on the discrete wavelet transform decomposed vibration signal. Finally, experiments are conducted comparing with the previous study, and the results show that the proposed control is effective to reduce the arm vibration in less time.

Operator-based robust nonlinear control of an uncertain wireless power transfer system using sliding mode technology

In this paper, a mathematical modelling of a wireless power transfer system with a buck circuit is presented. Based on this modelling, an operator-based robust nonlinear control design scheme using sliding mode technology is proposed to consider the uncertain coupling coefficient, which results from an inaccurate distance between the transmit coil and receive coil in the wireless power transfer system. The proposed control design scheme has two advantages. First, in order to tackle the uncertain coupling coefficient, operator-based right coprime factorization is applied to guarantee robust stability of the nonlinear system. Sliding mode technology is also adopted to guarantee the tracking performance of the nonlinear system. Finally, simulations and experiments of the wireless power transfer system are tested using the proposed control design scheme. Results of both the simulations and experiments show the effectiveness of the proposed control design scheme.

Experimental Study on Robust Nonlinear Forced Vibration Control for an L-Shaped Arm with Reduced Control Inputs

This paper presents an operator-based robust nonlinear control approach for an L-shaped arm vibration experimental system. The arm is driven by a linear pulse motor to move along a frame and controlled by a piezoelectric actuator in parallel. The aim of this paper is to allow the motor to move fast and reduce the arm vibration by controlling the motion of the motor and the piezoelectric actuator simultaneously. In detail, first, the vibration dynamics of the L-shaped arm is modeled based on the Euler–Bernoulli beam theory. The hysteresis of the piezoelectric actuator is modeled using a Prandtl–Ishlinskii hysteresis model. Second, by using operator-based robust right coprime factorization approach, the proposed control for the system is designed where the linear motor is optimally controlled to reduce the time consumption and the vibration at the vertical part of the arm. Meanwhile, with the hysteresis compensation, the piezoelectric actuator is used to further reduce the vibration at the horizontal part of the arm. Finally, the results of the experiment are demonstrated to verify the effectiveness of the proposed control scheme.

Operator-based robust nonlinear optimal vibration control for an L-shaped arm driven by linear pulse motor

An L-shaped arm driven by a linear pulse motor is considered in this paper, an operator-based robust nonlinear control approach is proposed to reduce the vibration of the arm. First, by separating the arm into two parts, its vibration dynamics is modelled based on Euler-Bernoulli beam theory. Second, by using operator-based robust right coprime factorization approach, two control schemes are designed, one for controlling the linear pulse motor move to the desired destination and reducing the vibration of the arm with optimal trajectory, another one is to control vibration of the arm by using a piezoelectric actuator, where a tracking compensator is designed to compensate the hysteresis of the piezoelectric actuator and make the arm vibration track to the reference values. Finally, simulation results are demonstrated to verify the effectiveness of the proposed control scheme.

A Miniature Pneumatic Bending Rubber Actuator Controlled by Using the PSO-SVR-Based Motion Estimation Method with the Generalized Gaussian Kernel

Soft actuators have been employed in various fields recently. A miniature pneumatic bending rubber actuator is one of the soft actuators. This actuator will be used for medical and biological fields. Its flexibility and high safety are suitable for fragile objects. However, its modeling is difficult due to its nonlinearity. There are no suitable sensors to measure the output of this actuator. In this paper, the particle swarm optimization-support vector regression (PSO-SVR)-based estimation method with the generalized Gaussian kernel is proposed. An experimental result with the operator-based robust nonlinear control system is employed to verify the effectiveness of the proposed method.

Operator-Based Robust Nonlinear Control Design of a Robot Arm with Micro-Hand

[abstFig src='/00280004/14.jpg' width='300' text='Robot arm with micro-hand system' ] This work focuses on a robust nonlinear control design of a robot arm with micro-hand (RAMH) by using operator-based robust right coprime factorization (RRCF) approach. In the proposed control system, we can control the endpoint position of robot arm and obtain the desired force of micro-hand to perform a task, and a miniature pneumatic curling soft (MPCS) actuator which can generate bidirectional curling motions in different positive and negative pressures is used to develop the fingers of micro-hand. In detail, to control successively the precise position of robot arm and the desired force of three fingers according to the external environment or task involved, this paper proposes a double-loop feedback control architecture using operator-based RRCF approach. First, the inner-loop feedback control scheme is designed to control the angular position of the robot arm, the operator controllers and the tracking controller are designed, and the robust stability and tracking conditions are derived. Second, the complex stable inner-loop and micro-hand with three fingers are viewed as two right factorizations separately, a robust control scheme using operator-based RRCF approach is presented to control the fingers forces, and the robust tracking conditions are also discussed. Finally, the effectiveness of the proposed control system is verified by experimental and simulation results.

Operator-Based Sliding-Mode Nonlinear Control Design for a Process with Input Constraint

<div class=""abs_img""><img src=""[disp_template_path]/JRM/abst-image/00270001/10.jpg"" width=""300"" />The process with constraint</div> In this paper, operator-based sliding-mode nonlinear control is presented for a process with input constraint. After the mathematical model is discussed for the water level process, it is seen that there exist uncertainty and input constraint in the process. Operator-based robust nonlinear control is then considered by using robust right coprime factorization method to eliminate the effect of uncertainty. Furthermore, operator-based sliding-mode nonlinear control is proposed to deal with the constrained input. Finally, simulation and experimental results are given to show the effectiveness of the proposed method. </span>

Robust tracking control design to nonlinear plants with perturbation using operator-based observers

In this paper, an operator-based robust tracking control design for nonlinear plants with perturbation is proposed by using robust right coprime factorisation approach and operator-based observers. In the real industrial process, most of the controlled systems have nonlinear characteristics, including unknown uncertainties consisting of modelling errors and external disturbances. Considering the nonlinearity and uncertainties, an operator-based robust nonlinear perfect tracking control using robust right coprime factorisation is investigated. That is, first, because the unknown uncertain plant generates difficulties in designing realisable operator controllers to obtain the desired tracking performance, an operator state observer and an operator disturbance observer based on nominal plant properties are designed to compensate the effect of uncertain plant. Second, a realisable operator-perfect tracking controller is designed to improve the control performance and to realise the perfect tracking. Based on ...

Operator-based robust control design for a human arm-like manipulator with time-varying delay measurements

In this paper, an operator-based robust nonlinear control for a human multi-joint arm-like manipulator with time-varying delay measurements is proposed by using robust right coprime factorization approach, a delay compensation operator and a forward predictive operator. That is, first, considering the uncertainties of dynamic model consisting of measurement error and disturbances, an operator-based nonlinear feedback control scheme is designed to eliminate effect of uncertainties. Second, an operator controller based on real measured data from human multi-joint arm viscoelasticity is presented to obtain desired motion mechanism of human multi-joint arm viscoelastic properties, the unknown time-varying delay measurements are described by a delay operator, the delay compensation operator is designed to remove the effect of unknown time-varying delay measurements, and the forward predictive operator is designed to compensate the term related to effect of central nervous system (CNS) during human multi-joint arm movements. The BIBO stability can be guaranteed and the tracking performance can be realized by the designed operator controller, the delay compensation operator and the forward predictive operator. Finally, the effectiveness of the proposed design scheme is confirmed by the simulation results based on experimental data.

Robust nonlinear multivariable tracking control design to a manipulator with unknown uncertainties using operator-based robust right coprime factorization

In this paper, an operator-based robust nonlinear multivariable tracking control for a manipulator with uncertainties is proposed by using a robust right coprime factorization approach. In general, there exist unknown modelling errors in measuring structural parameters of the manipulator and external disturbances in real situations. In the present control system design, the effect of the modelling errors and disturbance on system performance is considered to be uncertainties in the manipulator dynamics. Considering the uncertainties, an operator-based robust nonlinear multivariable tracking control using robust right coprime factorization is studied. That is, firstly a robustly stable control based on robust right coprime factorization is designed. Secondly, a robust nonlinear multivariable tracking system is proposed for improving the trajectory of the manipulator, and the output tracking performance is evaluated based on the exponential iteration theorem. Finally, the effectiveness of the designed system is confirmed by simulation results.

Operator-Based Robust Nonlinear Control for a Manipulator with Human Multi-Joint Arm-Like Viscoelastic Properties

Operator-Based Robust Nonlinear Control for a Manipulator with Human Multi-Joint Arm-Like Viscoelastic Properties

Operator-based robust non-linear control for gantry crane system with soft measurement of swing angle

In this paper, a robust non-linear control scheme is proposed for a gantry crane system with estimation of swing angle by using operator-based robust right coprime factorisation approach. By analysing properties of the crane system, it shows that displacement distance and swing angle are the two main goals. But, there exists only one input force. Also, in real gantry crane system, it is difficult to measure the swing angle. As a result, real-time estimation of the swing angle is presented by using data-based SVM model, where a generalised Gaussian function is adopted as the kernel function. The difference between the estimation and real value leads some uncertainties. Then, operator-based robust right coprime factorisation approach is presented for the non-linear system with uncertainties. Meanwhile, an optimal tracking controller is designed to ensure the tracking performance. Finally, experimental results are given to show the effectiveness of the proposed scheme.

Operator-based robust nonlinear control and its realization for a multi-tank process by using a distributed control system

In this paper, a robust nonlinear control design method using an operator-based robust right coprime factorization approach and its realization based on a distributed control system (DCS) device are considered for a multi-tank process. In detail, for the multi-tank process, consisting of a water-level process and a water-flow process, theoretical models are developed according to the Bernoulli theorem. Based on the obtained models, a robust nonlinear feedback control design is presented by using robust right coprime factorization for the multi-tank process. Further, from a large-scale industrial application viewpoint, the realization of the designed operator-based robust right coprime factorization controllers is considered by using a DCS device. Because there are some nonlinear functions in the designed controllers which cannot be realized straightforwardly in the DCS device such that the designed controllers need to be realized approximately. That is, there exist some parasitic terms for the approximated realization of the controllers in the real system. As a result, the parasitic terms and processes’ unknown uncertainties should be considered simultaneously. In this paper, a robust condition is derived to guarantee robust stability of the nonlinear feedback control system with the parasitic terms and the uncertainties. Moreover, tracking controller design problem for the multi-tank process is discussed. Finally, by using a DCS device (CENTUM CS3000), experimental results are given to confirm the effectiveness of the proposed design scheme.