Search

In the present research work, computational simulation of the double cavity scramjet combustor have been performed by using the two-dimensional compressible Reynolds-Averaged Navier–Stokes (RANS) equations coupled with two equation standard k–ɛ turbulence model as well as the finite-rate/eddy-dissipation reaction model. All the simulations are carried out using ANSYS 14-FLUENT code. Additionally, the computational results of the present double cavity scramjet combustor have been compared with experimental results for validation purpose which is taken from the literature. The computational outcomes are in satisfactory agreement with the experimentally obtained shadowgraph image and pressure variation curve. However, due to numerical calculation, the pressure variation curve obtained computationally is under-predicted in 5 locations. Further, analyses have been carried out to investigate the effect of variation of hydrogen injection pressure as well as the variation of air inlet temperature on the flow-field characteristics of scramjet engine keeping the Mach number constant. The obtained results show that the increase in hydrogen injection pressure is followed by the generation of larger vortex structure near the cavity regions which in turn helps to carry the injectant and also enhance the air/fuel mixing whereas the increase in the inlet temperature of air is characterised by the shifting of incident oblique shock in the downstream of the H2 injection location. Again for T0 = 1500 K, the combustion phenomena remains limited to the cavity region and spreads very little towards the downstream of the combustor.

This paper proposes a trajectory tracking problem of a non-holonomic mobile robot with differential driven wheels. The robust controller ensures the non linear system to reach the goal position. To ensure the dynamics of the encoders for both wheels of the mobile robot, a high gain observer is used. Furthermore, in trajectory tracking control, robustness is better with control loops. The convergence of the algorithm for backstepping control was proven by the simulation results.

A crucial problem in immersion based observer design is the case where the dimension of the immersed system is greater than that of the original system, and the analytical expression of the inverse of the immersion is unknown. In this paper, we have proposed a method for constructing observers for such autonomous nonlinear systems.

Optimized robust control for Polymer Electrolyte Membrane Fuel Cell (PEMFC) air-feed systems is an important challenge in improving the net fuel cell power output in automotive applications. This paper focuses on the practical implementation and performance comparison of robust and adaptive Second Order Sliding Mode Controllers (SOSMC) for this application. Both controllers aim to minimize the power consumption of the air-feed system by operating it to maintain the optimal oxygen excess ratio in the fuel cell. The controllers have been tested using a Hardware-In-Loop test bench based on a commercial twin screw compressor and 90 Cell, 33 kW fuel cell emulator. The experimental results demonstrate the effectiveness of both controllers and highlight that the adaptive controller is more power-efficient as the adaptive gains further reduce the internal power consumption of the air-feed system.

This paper presents an observer-based fault reconstruction method for PEM fuel cells. This method extends the results of a class of nonlinear uncertain systems with Lipschitz nonlinearities. An adaptive-gain second-order sliding mode (SOSM) observer is developed for observing the system states, where the adaptive law estimates the uncertain parameters. The inherent equivalent output error injection feature of SOSM algorithm is then used to reconstruct the fault signal. The performance of the proposed observer is validated through a hardware-in-loop emulator. The experimental results illustrate the feasibility and effectiveness of the proposed approach for application to fuel cell air-feed systems.

In this paper, an adaptive algebraic observer is proposed for a Polymer Electrolyte Membrane Fuel Cell (PEMFC) air-feed system, based on Higher Order Sliding Mode (HOSM) differentiators. The goal is to estimate oxygen and nitrogen partial pressures in the fuel cell cathode side, using measurements of supply manifold pressure and compressor mass flow rate. As the proposed technique requires the time derivatives of the states, Lyapunov-based adaptive HOSM differentiators are synthesized and implemented for estimating these derivatives without a-priori knowledge of the upper bounds of their higher order time derivatives. The performance of the proposed method is validated through experiments on a Hardware-In-Loop (HIL) test bench. These results illustrate the feasibility and effectiveness of the proposed approach.

This paper provides a reliable tool for simulating the effects of exhaust gas flow through the variable turbine geometry section of a variable geometry turbocharger (VGT), on flow control mechanism. The main objective is to estimate the resistive aerodynamic force exerted by the flow upon the variable geometry vanes and the controlling actuator, in order to improve the control of vane angles. To achieve this, a 1D model of the exhaust flow is developed using Navier–Stokes equations. As the flow characteristics depend upon the volute geometry, impeller blade force and the existing viscous friction, the related source terms (losses) are also included in the model. In order to guarantee stability, an implicit numerical solver has been developed for the resolution of the Navier–Stokes problem. The resulting simulation tool has been validated through comparison with experimentally obtained values of turbine inlet pressure and the aerodynamic force as measured at the actuator shaft. The simulator shows good compliance with experimental results.

Summary In this paper, we present an output feedback backstepping controller for mechatronic actuators with dynamic adaptive parameters for friction and load compensation. The targeted application is angular position control of automotive mechatronic valves, which possess nonlinear dynamics due to friction. The proposed controller requires only position measurement. The velocity, current, and friction dynamics are obtained by estimation and observation. The adaptive control law compensates the variations in friction behavior and load torque variation, which are common in real life applications. Lyapunov analysis has been used to show the asymptotic convergence of the closed-loop system to zero. Simulation and laboratory experimental results illustrate the effectiveness and robustness of the controller. Further experiments on an engine test bench demonstrate the applicability of this controller in commercial engines, as well as its effectiveness as compared with conventional PI controllers.Copyright © 2014 John Wiley & Sons, Ltd.

In this paper, we design, analyze, and experimentally validate an observer-based backstepping controller for electropneumatic actuators. These actuators are commonly used in diesel engines for variable geometry turbochargers (VGT) control. They are preferred over other actuation techniques due to better force/weight ratio; however, their drawbacks, such as nonlinear air mass flow, friction, and aerodynamic forces make their control as a challenging problem. The aim of this paper is to achieve precise control of the actuator by compensating friction and aerodynamic VGT forces. A Lyapunov-based output feedback controller is developed using backstepping technique. As the actuator position is the only measured state, pressure and friction states are obtained from sliding mode-based observers. The exponential convergence of the controller-observer closed-loop system is proved using Lyapunov analysis. Experimental results are presented, which demonstrate the effectiveness of the proposed controller.

In the engineering field, we are always facing with the system or process with nonlinear type which is not trivial to control its behaviour, and to response this problem we just equipped different type of sensors to be able to analyse the output measurement. Unfortunately, we can not use lot of sensor in a system due to its cost and also the limited in terms of technology examples: finding the temperature in a heater exchange or to know the impact of the wind on a car, etc. That is why we use to create the virtual sensor called observer to replace or make a redundancy with the physical sensor, by applying this type of sensor we can improve the performance of the system in terms of cost and especially in the case when we can not use the physical sensor. This paper proposes a mono-vision depth estimation method for mobile robots, based on high gain observers. The objective of this paper is to estimate the distance between the robot and target object by using only a camera fixed on-board. The proposed method switches between multiple observers in order to gauge the distance between the camera and the target object. Simulations and experimental results illustrate the practical applicability and benefits of this method for visual servoing.

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are extremely sensitive to load variations. A rapid load variation can damage the system in many ways. For this reason, a Load Governor (LG) based on constrained Extremum Seeking (ES) approach has been proposed in this paper. The LG controller ensures that the physical constraints of the system are not violated and the ES controller varies the LG bandwidth parameter to optimize the net power output. The proposed controller has been tested on a Hardware-In-Loop (HIL) emulation test bench, based on a commercial centrifugal compressor and a real time PEMFC emulator. Experimental results show a good performance of the proposed scheme during load variations.

This paper presents a synthesis of non-linearities present in mechatronic air path actuators of diesel engines. These actuators allow precise control over air path dynamics because of their fast response times and accuracy in transient conditions. However, the non-linearities present in their characteristics limit their closed-loop performance. In this paper we discuss various non-linear phenomena existing in actuator characteristics and their physical causes. Different modelling schemes for the physical causes are also presented, which simulate the non-linear behaviour of the actuators. Furthermore, other factors, such as operational conditions and ageing, and their degrading effects on the actuator performance, are also discussed.

Numerous advanced control techniques for actuator control of an engine’s air path have been developed in recent years. Among these approaches, the performance of sliding mode controllers stands out due to their robustness against changes in the physical conditions around the engine. This paper presents the design and testing of three high-order sliding mode controllers and a comparison of their performance in controlling a mechatronic engine air path valve. The most effective strategies are further tested for their robustness against variations in temperature and load conditions. The experimental results show the effectiveness and robustness of the controllers. Comparative results are presented that allow the performance of the considered algorithms to be compared both with respect to each other and with respect to sliding surfaces.

This article is focused on the working, modeling and control of pancake DC torque motors, used in automobile engine air path actuators. These motors, with a limited working angle, provide high torque which makes them suitable for use in actuators without any additional gear reduction. The torque is a nonlinear function of the motor angle. This article provides a modeling scheme, suitable for control purposes, which takes into consideration nonlinearities arising from friction and operating temperature. Comparison between simulation and experiments shows the effectiveness of the proposed model. Second order sliding mode control has been applied to the actuators for robust control under the influence of nonlinearities and uncertainties. The effectiveness of the control algorithm has been proven experimentally.

In this article, we have addressed the control problem of unicycle path following, using a rigidly attached target point. The initial path following problem has been transformed into a reference trajectory following problem, using saturated control laws and a geometric characterization hypothesis. This hypothesis links the curvature of the path to be followed with the target point. The proposed controller allows global stabilization, without restrictions on initial conditions. The effectiveness of this controller is illustrated through simulations.

This paper presents the application of higher order Sliding Mode observers (SMO) for state observation and friction estimation of an engine air path actuator. The actuator model incorporates LuGre Friction Model for dynamic friction modeling. The study has two objectives, to observe the system dynamics and the friction dynamics, and to use the equivalent output injection to estimate the parameters of the LuGre model. Cascaded sliding mode observers have been used to observe system and friction dynamics separately. Friction force has been estimated using the Equivalent output injection of the observer, considering friction as an unknown external input. Through this estimation, identification of the LuGre model parameters becomes simplified. Simulation and experimental results show the effectiveness of the proposed observation and identification scheme.

International audience; In this brief, we present Lyapunov-based robust and adaptive higher order sliding mode (HOSM) controllers for the air-feed system of polymer electrolyte membrane fuel cells, which is a nonlinear single-input, single-output system with bounded uncertainty. The system consists of a motorized compressor, which is driven at its optimal point in order to minimize the internal energy consumption of the system. This brief provides an experimental demonstration of the applicability of the recently developed fixed-gain robust controller and adaptive controller for this problem. Third-order controllers are developed in order to obtain a continuous profile for the input current of the compressor motor. In this regard, a complete adaptive arbitrary HOSM control has been presented for the first time, with Lyapunov-based proof. A performance comparison between the two controllers is presented in the end.

The success of an electric vehicle Fleet operation, engaged in vehicle-to-grid (V2G) depends largely upon the reliable ICT technology that guarantees deterministic data transfer between the fleet aggregator, vehicles and other actors. In this paper, we present a prototype ICT architecture and simulator for Fleet based V2G operation. The prototype is based on IEC standards and has been developed to optimize messaging and information exchange such that communication delays are minimized and bottlenecks are avoided. The presented prototype can be used to develop a VGT architecture for EV Fleet operators, on any scale.

International audience; In this article, we have addressed the control problem of unicycle path following, using a rigidly attached target point. The initial path following problem has been transformed into a reference trajectory following problem, using saturated control laws and a geometric characterization hypothesis. This hypothesis links the curvature of the path to be followed with the target point. The proposed controller allows global stabilization, without restrictions on initial conditions. The effectiveness of this controller is illustrated through simulations.

In this paper, higher order sliding mode (HOSM) observers have been applied for state observation of an engine air path actuator. The cascaded observation scheme is based on a detailed physical model of the actuator, ([28], [1])which includes LuGre friction model. Two cascaded observers provide actuator dynamics and friction dynamics separately. Equivalent Output Injection, a property of HOSM observers, has been exploited to calculate friction force as an unknown external input. Taking advantage of this additional information, a method to identify the parameters of the LuGre model has also been presented. The identification has been verified using simulation and experimental results.

In this paper, we have applied sliding mode extremum seeking control for optimizing the net power output of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The output of a PEMFC is regulated by controlling the air, which is supplied through a compressor. The control objective is to ensure that the the oxygen excess ratio is maintained between 2 and 2.4, while the power consumed by the compressor is kept at minimum. The proposed control strategy is based on an improved extremum seeking control technique, based upon second order sliding mode control. This allows the controller to respond to sudden changes in load. Simulation results show the effectiveness of the applied control technique.

This paper is aimed at robust control of a Permanent magnet DC motor based actuator used in the control of the inlet swirl valve of a diesel engine. The actuator has uncertainty issues related to parameter identification and variation, and load disturbance. These issues lead to faults in controllers, resulting in poor performance and failure. The actuator has been modeled taking parameter uncertainties and friction nonlinearities into account. To cope with these uncertainties, an outputfeedback control system has been developed by means of output 2nd order sliding-mode control. The controller is expected to compensate for nonlinearities, thereby avoiding operational faults related to them. Practical implementation of the controller on an experimental setup shows the effectiveness of this controller.

This paper addresses the physical modeling and identification of Torque Motor based mechatronic actuators used in the air path of the engine of a Drive-by-Wire automobile. The torque motor has non-linear torque characteristics with respect to the rotor position due to its mechanical construction. A study based on two Pancake DC Torque motors has been carried out with two motors of different stator construction. A physical model has been proposed and its parameters have been identified for the two motors. Special attention has been paid on modeling nonlinearities due to torque characteristics and friction. LuGre friction model has been used to incorporate friction nonlinearities. Comparison between simulation and experimental results shows the effectiveness of the proposed model.

This paper discusses the analytical model of a pneumatic actuator. Nonlinear hysteresis phenomenon resulting from the friction is also presented in this article. Hysteresis phenomenon governed by the friction in the actuator is modeled with dynamic friction (LuGre) model. Moreover, effects of friction model parameters on the over all model are also discussed. This new approach allows for the sensitivity analysis for the pneumatic actuator.

This paper addresses the physical modeling and identification of an EGR Actuator. The EGR actuator has a nonlinear behavior due to its mechanical construction and different friction forces. A nonlinear physical model for an EGR actuator manufactured by Valeo is presented here. Special focus has been given to modeling frictions with the Dahl Model. Different parts of the actuator and friction have been identified. Comparison between simulation and experimental results shows the effectiveness of the proposed model. The model can act as a reference to characterize different designs and future control strategies.

Laboratoire OPERA, Universite de Technologie de Belfort-Montbeliard, Belfort, FranceTheauthorsregretthatthecorrespondingauthoraffiliationwaslistedincorrectly.Thecorrespondingauthoraffiliationshouldbelisted as follows:* Corresponding author: Control Science and Engineering, Harbin Institute of Technology, Harbin, China.The authors would like to apologize for any inconvenience.