Extended Sliding Mode Observer Research Articles

Simultaneous Identification of Load Torque and Moment of Inertia of PMSM Based on Variable Structure Extended Sliding Mode Observer

Simultaneous Identification of Load Torque and Moment of Inertia of PMSM Based on Variable Structure Extended Sliding Mode Observer

Robust Constant Exponent Coefficient Fixed-Time Control Based on Finite-Time Extended Sliding Mode Observer of Permanent Magnet Synchronous Motors

This paper presents the Robust Constant Exponent Coefficient Fixed-Time Control (CECFSMC), an innovative control technique for precisely regulating the speed of a permanent magnet synchronous motor (PMSM) by utilizing fixed-time stability with constant exponent coefficients to provide not only faster convergence but also in a specific period of time. The effect of chattering is also lessened. To ensure that the designed controller produces the desired performance under bounded disturbances, a finite-time extended sliding-mode observer (ESMO) is also designed to estimate the PMSM velocity while also estimating lumped load disturbances. The considered PMSM is the surface-mounted PMSM. Finally, a numerical simulation with PMSM drive shows good robustness against load disturbances, better convergence, and a reaching time of less than 2 s, thereby demonstrating that the proposed fixed-time constant exponent coefficient offers good performance and is much simpler than the conventional finite-time method.

Extended Sliding Mode Observer-Based Output Feedback Control for Motion Tracking of Electro-Hydrostatic Actuators

This paper develops a novel output feedback control scheme for the motion-tracking problem of an electro-hydrostatic actuator (EHA) in the presence of model uncertainties and external disturbances. Firstly, a simplified third-order system model of the studied EHA is established using theoretical methods. For the first time, an extended sliding mode observer (ESMO) is introduced to simultaneously account for the shortage of unknown system states and modeling imperfections. Based on this, a robust nonlinear controller is developed using the backstepping control framework to stabilize the closed-loop system. This controller integrates estimates of immeasurable system states and lumped disturbances to deal with their adverse impacts. Moreover, the dynamic surface control (DSC) technique is employed to effectively mitigate the computational burden of the traditional backstepping framework. An ultimately uniformly bounded (UUB) performance is assured by using the recommended method. Furthermore, the stability of not only the observer but also the closed-loop system is concretely analyzed by using the Lyapunov theory. Finally, experiment results under various working scenarios are given to convincingly demonstrate the advantage of the suggested method in comparison with some reference control approaches.

Tracking Control Method of Multi Motor Actuator Saturation Based on Total Amount Consistency

In collaborative control of multi motors for heavy-duty locomotives, the output value of the motor frequently exceeds its maximum allowable value during power redistribution. This results in a saturated motor owing to the power redundancy of each wheel set of the train. In this study, an algorithm for the tracking control of a consistent total amount of the extended observer through anti-saturation is proposed. First, mathematical models of multi-motor traction systems are developed. The system includes uncertain parameter perturbations and external perturbations. Second, a new type of extended sliding mode observer (ESMO) is designed to reduce the influence of the tracking effect on the input saturation of the system. Subsequently, for collaborative control of multi motors in heavy-duty locomotives, a new scheme for dynamic and auxiliary anti-saturation compensation (anti-windup) is established. The perturbation observation results and the systems’ auxiliary status are respectively input into the sliding mode controller (SMC). A traction total-amount coordinated tracking control (TACTC) of multi motors is achieved to ensure consistency of the system’s total output torque and the given traction characteristic curve. Finally, simulations and tests are performed on the motor actuators to demonstrate a good control effect.

An Integrated Observer Framework Based Mechanical Parameters Identification for Adaptive Control of Permanent Magnet Synchronous Motor

An integrated observer framework based mechanical parameters identification approach for adaptive control of permanent magnet synchronous motors is proposed in this paper. Firstly, an integrated observer framework is established for mechanical parameters' estimation, which consists of an extended sliding mode observer (ESMO) and a Luenberger observer. Aiming at minimizing the influence of parameters coupling, the viscous friction and the moment of inertia are obtained by ESMO and the load torque is identified by Luenberger observer separately. After obtaining estimates of the mechanical parameters, the optimal proportional integral (PI) parameters of the speed-loop are determined according to third-order best design method. As a result, the controller can adjust the PI parameters in real time according to the parameter changes to realize the adaptive control of the system. Meanwhile, the disturbance is compensated according to the estimates. Finally, the experiments were carried out on simulation platform, and the experimental results validated the reliability of parameter identification and the efficiency of the adaptive control strategy presented in this paper.

Moment of inertia identification for PMSM based on extended SMO and improved RBFNN

As an important mechanical parameters of permanent magnet synchronous motor (PMSM), the moment of inertia determines the control optimization and condition monitoring performance of the controller. However, since inertia cannot be measured directly, it is necessary to choose an appropriate method to identify inertia. In this paper, an extended sliding mode observer (ESMO) is proposed by taking the motor speed and inertia as the extended state variable of the observer to identify the inertia. A deformation mode of a saturation function is used as the switching function to mitigate the chattering phenomenon of conventional SMO. For unknown disturbance torque in the state equation, an improved radial basis function neural network (RBFNN) is proposed to estimate it. The improved RBFNN determine the RBF center through the eigenvector of the input data and then trains the neural network, which improves the training accuracy. The effectiveness of the method is verified by simulation experiments. The experiments show that the ESMO combined with the improved RBFNN can effectively and accurately identify motor inertia which is a method worthy of reference.

A Novel Trajectory Adjustment Mechanism-Based Prescribed Performance Tracking Control for Electro-Hydraulic Systems Subject to Disturbances and Modeling Uncertainties

This paper proposes a novel active disturbance compensation framework for exactly positioning control of electro-hydraulic systems (EHSs) subject to parameter deviations, unknown dynamics, and uncertain external load without velocity measurement mechanism. In order to accurately estimate and then actively compensate for the effects of these uncertainties and disturbances on the system dynamics, a combination between an extended sliding mode observer (ESMO) and a linear extended state observer (LESO) is firstly established for position control of EHSs. In addition, an inherited nonlinear filter-based trajectory planner with minor modifications is utilized to overcome the barriers of inappropriate desired trajectories which do not consider the system kinematic and dynamic constraints. Furthermore, for the first time, the command filtered (CF) approach and prescribed performance control (PPC) are successfully coordinated together and dexterously integrated into the backstepping framework to not only mitigate the computational cost significantly and avoid the “explosion of complexity” of the traditional backstepping design but also satisfy the predetermined transient tracking performance indexes including convergence rate, overshoot, and steady-state error. The stabilities of the observers and overall closed-loop system are rigorously proven by using the Lyapunov theory. Finally, comparative numerical simulations are conducted to demonstrate the advantages of the proposed approach.

Extended sliding mode observer based robust adaptive backstepping controller for electro-hydraulic servo system: Theory and experiment

This paper firstly presents an extended sliding mode observer (ESMO) for the electro-hydraulic servo systems (EHSSs) to deal with nonlinear factors like the external disturbance, parameter uncertainties as well as unmodeled characteristics in the EHSS. The model for the EHSS is established by taking these nonlinear factors into consideration and then the statespace representation is obtained. According to the state space, the ESMO for the EHSS is presented, the equivalence principle is properly utilized to simplify the ESMO and some saturation functions are employed to eliminate high frequency interferences caused by the chattering phenomenon. Based on estimated values from the ESMO, a robust adaptive backstepping controller (RABC) is presented in detail with taking some parameter uncertainties into consideration to further improve the tracking performance. The proposed controller has the following advantages: (1) utilizing the ESMO to cope with these nonlinear factors; (2) parameter online adaptive laws are employed in the RABC design to further improve the tracking performance. In order to verify the performance of the proposed controller, an experiment bench was established. Two sine waves reference signal (one amplitude 0.01 m, 1 Hz; the other 0.015 m, 2 Hz) are employed to verify the performance of the controller. Comparative experimental results show that: (1) the tracking performance of the proposed controller is better than that of a DOs based BC, a BC and a PI controller; (2) estimation values from the ESMO contains fewer noise than two conventional disturbance observers (DOs), which will decrease the control input ripples.

Extended Sliding Mode Observer-Based Admittance Control for Hydraulic Robots

In this letter, an admittance control algorithm has been proposed for hydraulic robots in the presence of model uncertainties, external disturbances, and system nonlinearities without contact force sensors. An extended sliding mode observer (ESMO) is firstly developed based on joint force sensors and pressure signals in chambers of hydraulic actuators to estimate not only the contact force with an environment but also the joint velocities which are robust to unknown friction in hydraulic actuators. Matched uncertainties and disturbances in actuator dynamics are observed by a matched disturbance observer. These techniques are integrated into the backstepping framework to handle high nonlinearities in the hydraulic and mechanical systems and achieve the desired admittance behavior of the robotics system. Simulation results are conducted with a two-degree-of-freedom (2-DOF) hydraulic leg robot with different case studies, which verifies the effectiveness of the proposed control method.

Predictive Current Control for PMSM Systems Using Extended Sliding Mode Observer With Hurwitz-Based Power Reaching Law

An extended sliding mode observer (ESMO) with Hurwitz-based power reaching law (HPRL) is proposed in this article to improve the performance and the robustness of predictive current control (PCC). First, extended state-space realizations of permanent magnet synchronous motor (PMSM) stator currents mathematical model are introduced by incorporating parameter mismatches as lumped disturbance and state variables. ESMO with a multidimensional sliding mode surface is designed to estimate the stator current and the lumped disturbance. Second, based on the Hurwitz criterion, HPRL is proposed to eliminate the uncertain disturbance calculation of classical power reaching law. Compared with exponential reaching law, HPRL adopted in ESMO achieves high convergence rate and settles chattering. Third, the predictive current discrete model and the predictive lumped disturbance model are presented by using ESMO-HPRL for PCC cost function evaluation. The experimental results validate high robustness and excellent steady and dynamic performance of PCC-ESMO-HPRL in PMSM systems compared with conventional method.

Robust Fault-Tolerant Synergetic Control for Dual Three-Phase PMSM Drives Considering Speed Sensor Fault

Stability and reliability are the most important indicators of drive systems. In this article, a robust nonlinear control method is advanced for dual three-phase permanent-magnet synchronous machine (dual-PMSM) drives, based on the synergetic control theory. This control is implemented by a new synergetic controller (SGC) integrating with an extended sliding mode observer (ESMO), and an optimization method is applied to obtain the optimal parameters of the SGC. This control scheme not only improves the dynamic performance even with operating parameters change, but also can diagnose the speed sensor fault and realize the fault tolerant control (FTC). The proposed control method is compared with the PI control, the sliding mode control (SMC) and the predictive control, as well as the simulation and experimental results confirm the superior dynamic performance and the effectiveness on the speed sensor fault diagnosis (FD) and FTC.

Sliding Mode Observer-Based Parameter Identification and Disturbance Compensation for Optimizing the Mode Predictive Control of PMSM

This paper reports on the optimal speed control problem in permanent magnet synchronous motor (PMSM) systems. To improve the speed control performance of a PMSM system, a model predictive control (MPC) method is incorporated into the control design of the speed loop. The control performance of the conventional MPC for PMSM systems is destroyed because of system disturbances such as parameter mismatches and external disturbances. To implement the MPC method in practical applications and to improve its robustness, a compensated scheme with an extended sliding mode observer (ESMO) is proposed in this paper. Firstly, for observing if and when the system model is mismatched, the ESMO is regarded as an extended sliding mode parameter observer (ESMPO) to identify the main mechanical parameters. The accurately obtained mechanical parameters are then updated into the MPC model. In addition, to overcome the influence of external load disturbances on the system, the observer is regarded as an extended sliding mode disturbance observer (ESMDO) to observe the unknown disturbances and provide a feed-forward compensation item based on the estimated disturbances to the model predictive speed controller. The simulation and experimental results show that the proposed ESMO can accurately observe the mechanical parameters of the system. Moreover, the optimized MPC improves the dynamic response behavior and exhibits a satisfactory disturbance rejection performance.

Satellites Autonomous Navigation With an Extended State and Disturbance Sliding Mode Observer Method

This paper considers the satellites autonomous navigation problem with an extended sliding mode observer method. First, on consideration that the relative dynamic equation of chaser and target spacecrafts refers to a nonlinear time-varying system, a transformation is performed on the original relative dynamic equation to obtain a linear time-invariant system with a nonlinear part. Second, an augmentation strategy is made on the new system to obtain a descriptor system. A new extended sliding mode observer is then designed for the descriptor system which can generate the simultaneous estimation of state and output measurement noise. Based on the observer estimates, the equivalent output error injection approach is used to estimate the space disturbance moment. Finally, an example is presented to demonstrate the effectiveness of the developed satellites autonomous navigation observer method.

Extended sliding mode observer based control for Markovian jump linear systems with disturbances

This paper addresses the problem of disturbance rejection control for Markovian jump linear systems with matched and mismatched disturbances. Based on the state and disturbance estimates obtained by the proposed discontinuous or continuous extended sliding mode observers, the composite controllers are designed to actively reject the disturbance. Moreover, the problem of stochastic stability analysis for the estimation error systems and the closed-loop systems are also performed respectively. Finally, a numerical example is provided to illustrate the efficiency and advantage of the proposed methods.

An Extended Sliding Mode Observer for Speed, Position and Torque Sensorless Control for PMSM Drive Based Stator Resistance Estimator

This paper presents a robust sixth-order Discrete-time Extended Sliding Mode Observer (DESMO) for sensorless control of PMSM in order to estimate the currents, speed, rotor position, load torque and stator resistance. The satisfying simulation results on Simulink/Matlab environment for a 1.6 kW PMSM demonstrate the good performance and stability of the proposed ESMO algorithm against parameter variation, modeling uncertainty, measurement and system noises.

Nonlinear Feedback Linearization and Observation Algorithm for Control of a Permanent Magnet Synchronous Machine

The aim of this study is to present a high dynamic current control and speed estimation strategy for Permanent Magnet Synchronous Motor (PMSM) drives without a speed transducer. The strategy is based on the exact linearization methodology and Extended Sliding Mode Observer (ESMO) algorithm. The performances of the proposed control strategy are analysed by simulations for a 1.6 kW PMSM. The obtained results show the effectiveness of the proposed robust current control approach and speed observation algorithm under load torque and stator resistance variation.

Real-time Estimation of Rotor Time Constant and Flux of an Induction Motor: Experimental Results

In this study, a reduced-order discrete-time Extended Sliding Mode Observer (ESMO) is introduced for on-line estimation of rotor fluxes and rotor time constant. The satisfying simulations and experimental results carried out on a 5.5 kW induction motor demonstrate the excellent performance and high robustness of the proposed ESMO against parameter variations, modeling uncertainty and measurement noise. It is concluded that the implementation in real-time of this reduced-order ESMO in the industrial applications, compared with the full-order ESMO, permit on the one hand to overcome the heavy computational effort, complexity and hard tuning of the estimation algorithm and on the other hand, to reduce the execution time of the observation with a good accuracy and considerable rapidity.