Higher Order Sliding Mode Observer Based Fast Composite Backstepping Control for HESS in DC Microgrids

International audience

This paper develops a new method to control uncertain robot manipulators by using only position measurements. The controller is designed based on a combination of a computed torque controller (CTC) with a higher-order sliding-mode observer and a fuzzy compensator. First, three higher-order sliding-mode (SM) observers (second-order SM, third-order SM and third-order SM linear (TOSML) observers) are designed and compared to verify whether the TOSML observer is the best for observing velocity and identifying uncertainty. A combined CTC-TOSML controller was then designed. Although this controller scheme can overcome the drawbacks of conventional CTCs, its tracking performance can still be improved. To enhance capability of the tracking performance, a CTC-TOSML controller plus fuzzy compensator called a CTC-TOSML-Fuzzy controller is proposed. The proposed controller increases the potential of the CTC for real robot applications. Finally, computer simulation results on a PUMA560 robot are discussed to verify the effectiveness of the proposed strategy.

The paper pertains to model validation and novel higher order sliding mode observer design for estimating precursor concentration of a nuclear research reactor. The linear and non-linear models of Pakistan Research Reactor-1 have been tuned and validated with experimental data. These models are subsequently used for higher order sliding mode observer design and performance evaluation. After lab experimentations, the non-linear and linear models of PARR-1 have been validated by giving desired motion to the control rod and recording output power change at the actual reactor. The mathematical model of the overall system, from control rod movement to output power change is validated with different sets of data at different operating points. Based on the validated model a robust nonlinear observer for estimating precursor concentration has been developed by using second order sliding mode technique. The observer estimates this variable with only the measurement of neutron flux available. The estimated value is in close agreement with the theoretically calculated value.

In this paper, an experimental validation of vertical forces estimation is presented. An original method using high order sliding mode observer is developed. The test bench is a static vehicle excited vertically by hydraulic jack. It's equipped by different sensors in order to measure its dynamics. Real time tests are done and results are presented in this paper.

This work presents a nested super-twisting second-order sliding mode speed controller for a brushless direct current motor with a high order sliding mode observer used for back electromotive force (back-EMF) estimation. Due to the trapezoidal nature of the back-EMF, a modified Park transformation is used in order to achieve proper field orientation. Such transformation requires information from the back-EMF that is not accessible. A second-order sliding mode observer is used to estimate the back electromotive forces needed in the modified transformation. Sliding mode control is known to be robust to matched uncertain disturbances and parametric variations but it is prone to unmatched perturbations that affect the performance of the system. A nested scheme is used to improve the response of the controller in presence of unmatched disturbances. Simulations performed under similar conditions to real-time experimentation show a good regulation of the rotor speed in terms of transient and steady-state responses along with a reduced torque ripple.

Aiming at the robust attitude control issue on reentry vehicle subject to uncertainties and disturbances. A novel optimal predictive attitude control method integrating with a high order sliding mode observer is proposed in this paper. On the one hand, the proposed optimal one-step predictive control approach can guarantee good dynamic performance of the control system, on the other hand, a high order sliding mode observer is applied to estimating the uncertainties and disturbances exactly, which can strengthen the robustness of the control system. System stability is strictly proved by Lyapunov theory and the domains of convergence are given exactly with/without the observer. Finally, an attitude predictive control law is presented for a reentry vehicle with dynamic characteristic of the actuators. Numerical simulations demonstrate the effectiveness of the proposed control law.

In this paper, we present the design of observer based event-triggered sliding mode control (ETSMC) for a chain of integrator system in the presence of matched uncertainties. In the scenario, where only output information is available, the observer is needed to observe all the states of the system. If a Luenberger observer is used the robustness property cannot be achieved, so it is appealing to use sliding mode observer (SMO). But conventional SMO does not give finite time convergence of all the observed states to their true values. Consequently, we use a higher order SMO (HOSMO) to observe all the states of the system in finite time. Also, to reduce computational effort, the behaviour of the system is analysed using this observer in the event-triggered environment. For this an ETSMC is proposed using these observed states and stability of the system is proved using Lyapunov analysis. It is also proved that the triggering instants generated using the proposed triggering rule do not lead to Zeno behaviour. Finally, the effectiveness of the proposed method is shown by simulation of a third order chain of integrator system.

Barrier Lyapunov function-based robust flight control for the ultra-low altitude airdrop under airflow disturbances

This paper deals with the design of fault detection and isolation (FDI) scheme on the basis of high order sliding mode observer for permanent magnet synchronous motors(PMSM). More precisely, the main advantage of the use of high order sliding mode techniques is that it allows to avoid the chattering phenomenon which is inherent to the classical first order sliding mode observers and controllers. The efficiency of the proposed observers is illustrated on a Matlab/Simulink simulator.

This paper investigated the trajectory tracking control problem of quadrotor UAVs with multi-source disturbances and actuator faults. Both the actuator faults and multi-source disturbances are viewed as part of the lumped disturbances, and the high-order sliding mode observers are introduced to estimate the lumped disturbances, Based on the disturbance estimations, a composite dynamic inverse control scheme is prosed. Simulation results validate that the proposed method significantly improves the disturbance rejection performance and fault tolerance performance of the quadrotor UAVs.

A robust finite-time control (FTC) framework using continuous terminal sliding-mode control (SMC) and high-order sliding-mode observer (HOSMO) is discussed to realize the trajectory tracking of flexible-joint robots in this article. Control performances of the robots always suffer from unknown matched and mismatched time-varying disturbances. Traditional SMC exists with a chattering phenomenon and cannot cope with mismatched time-varying disturbances due to its inherent structure property. For this reason, two HOSMOs are devised to estimate the time-varying disturbances on the link and motor side, respectively. Then, by fusing the states and disturbance estimations into a novel terminal sliding-mode surface, a continuous robust FTC scheme is developed. The proposed control strategy can not only handle both matched and mismatched time-varying disturbances but also obtain a finite-time convergence performance. The rigorous finite-time stability analysis of the closed-loop system under the proposed control method is guaranteed. The results are illustrated to verify the effectiveness and robustness of the proposed design approach.

Sensor or measurement noise is an immanent disturbance in all closed loop control systems. State observers are not robust to sensor noise. Higher Order Sliding Mode Observer (HOSMO) attenuates the estimation error to a small bound in presence of output noise. A strategy is proposed in this paper for HOSM observer design which provides a further attenuation of the estimation error. A recursively designed HOSM observer with integral surface is the proposed approach. The designed observer is also shown to comply continuity condition as required by super twisting controller. Simulation results are presented to validate the proposed method.

This article proposes an intelligent and fast controller for the parallel dc-dc converters in the islanded dc microgrids (DCMGs) in the shipboard power system (SPS) applications. The existence of constant power loads and propulsion loads in the SPS makes the voltage regulation an important issue in the islanded DCMG. In this article, the goal is to provide a fast response and proper voltage regulation and optimal current sharing in the stand-alone shipboard DCMG. To achieve this, a nonlinear I-V droop control is first designed in the primary control level to ensure the basic performance. Then, a new model-independent technique, entitled intelligent single-input interval type-2 fuzzy logic controller (iSIT2-FLC) combined with sliding mode control (SMC), is suggested to further improve the voltage regulation and current-sharing accuracy. In this control scheme, an extended state observer (ESO) is employed to estimate the unknown DCMG dynamics, whereas the SMC is adopted to eliminate the ESO estimation error. Moreover, the dynamic consensus algorithm (DCA) is implemented at the secondary control level to achieve coordinated control between DGs in the SPS. The effectiveness and applicability of the new suggested control approach are validated with hardware-in-the-loop (HiL) experimental results.

The key to the launching control of a dual-clutch transmission (DCT) lies in the coordination control of the engine and dual clutches, along with the accurate closed-loop control of the torque transmitted by each clutch and the output torque of the engine. The implementation feasibility and precision of the clutch torque closed-loop control are completely dependent on the effective real-time estimation of the clutch torque, which cannot be directly measured. Therefore, the high-order sliding-mode observer and unknown input observer are used to estimate the transmitted torque of the twin clutches on the basis of the self-designed control strategy and estimation of the vehicle drag torque. First, for the launching clutch slipping phase, an improved engine constant speed control is proposed based on the dynamic equations of a dry DCT with dual intermediate shafts, and the minimum value principle is applied to achieve the optimum launching control of the clutches. Meanwhile, the separating conditions of the separated clutch and the torque distribution are determined to ensure approximate friction work and avoid power cycle, and the target curve of the clutch-transmitted torque is obtained according to different conditions. Then, the vehicle drag torque is estimated using the recursive least-square method with a double forgetting factor, the angular acceleration of the engine and output shaft is refactored utilizing a high-order sliding-mode observer algorithm, and the transmitted torque of the twin clutches are estimated using the unknown input observer. Then, the DCT launching process is simulated under different driving conditions on the MATLAB/Simulink software platform. Finally, the bench test is conducted to verify the effectiveness of the self-designed clutch torque estimation method. The simulation and hardware-in-the-loop (HIL) test results show that the proposed methods of high-order sliding-mode observer and unknown input observer can effectively estimate the clutch-transmitted torque and lay a solid foundation for the subsequent development of the launching control strategy for a real vehicle with a DCT.

Robust nonlinear control of regenerative fuel cell, supercapacitor, battery and wind based direct current microgrid