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Output Feedback Active Suspension Control With Higher Order Terminal Sliding Mode
Rath, Jagat Jyoti,Defoort, Michael,Karimi, Hamid Reza,Veluvolu, Kalyana Chakravarthy Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol. No.
<P>The control of an automotive suspension system using hydraulic actuators is a highly complex nonlinear control task dealing with system nonlinearities, external disturbances, and uncertainties. In this work, an output feedback active suspension control scheme is proposed to achieve a ride comfort while maintaining the road holding for the vehicle. To design the controller, the states of the nonlinear system are first estimated using a highgain observer where the suspension stroke is the only measurable output. The controller is then designed using a recursive derivative nonsingular higher order terminal sliding mode approach that avoids singularity. The practical stability for the closed-loop observer-controller pair is established. Simulation results for the quarter-wheel vehicle over various road conditions demonstrate the effectiveness of the proposed control in improving the suspension performance in both the time and frequency domains.</P>
Hybrid sliding mode observer for switched linear systems with unknown inputs
Van Gorp, J.,Defoort, M.,Veluvolu, K.C.,Djemai, M. Pergamon Press [etc.] 2014 Journal of the Franklin Institute Vol.351 No.7
This paper addresses the state observation and unknown input estimation of a class of switched linear systems with unknown inputs. This class of systems may have modes in which the state is not fully observable. A state transformation allows implementing two suitable reduced-order observers. The first one, based on second order sliding mode techniques, is proposed to reconstruct the discrete state in the presence of unknown inputs. The second one, based on gathering partial information from individual modes of the switched system and on higher order sliding mode techniques, is introduced to estimate the continuous state. Then, the observer injection signal of the first second order sliding mode observer is used to estimate the unknown inputs. Simulation results highlight the efficiency of the proposed method.
Higher-order sliding mode observer for estimation of tyre friction in ground vehicles
Rath, Jagat Jyoti,Veluvolu, Kalyana Chakravarthy,Defoort, Michael,Yeng Chai Soh IET 2014 IET control theory & applications Vol.8 No.6
<P>The estimation of friction coefficient for a vehicle when it traverses on different surfaces has been an important issue. In this work, the longitudinal vehicle dynamics, the torsional tyre dynamics and the non-linear LuGre friction dynamics are integrated to model the quarter vehicle dynamics. The road adhesion coefficient in the vehicle dynamics is unknown and varies with the contact surface. To address this issue, the authors consider a class of non-linear uncertain systems that covers the vehicle dynamics and develop a higher-order sliding mode observer based on supertwisting algorithm for state and unknown input estimations. Under Lipschitz conditions for the non-linear functions, the convergence of the estimation error is established. By estimating the road adhesion coefficient, the coefficient of friction can be estimated. Simulation results demonstrate the effectiveness of the proposed observer for state and unknown input estimation.</P>
The Effect of Material Composition on the Strength of a Steam Explosion
Song, Jin Ho,Min, Beong Tae,Defoort, Francoise Taylor Francis 2008 Heat transfer engineering Vol.29 No.8
<P> To investigate the fundamental mechanism behind the recent experimental observation that the composition of a material considerably affects the strength of a steam explosion, physical and chemical analyses for the fast-quenched particles of a prototypic corium were performed. Six cases including fully oxidized and partially oxidized corium were selected for the study, in which the melt composition was changed, while the other initial and boundary conditions of the molten fuel and water interaction tests, such as the melt temperature, amount of water, and free fall height, were maintained the same. The proposition that the inner structure and solidification behavior of particles due to the existence of a mushy phase are responsible for the strong influence of the material composition on the strength of a steam explosion was examined from the results of physical and chemical analysis. The results of the present analysis are supportive of the proposed argument.</P>
Rath, J. J.,Veluvolu, K. C.,Defoort, M. Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system.</P>
Simultaneous Estimation of Road Profile and Tire Road Friction for Automotive Vehicle
Rath, J. J.,Veluvolu, K. C.,Defoort, M. IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.10
<P>The longitudinal motion control of automotive vehicles is heavily reliant on information about the time-varying tire road friction coefficient. In the presence of varying road roughness profiles, the effective vertical load on each wheel varies dynamically, influencing the tire friction. In this paper, we integrated the vertical and longitudinal dynamics of a quarter wheel to form an integrated nonlinear model. In the modeled dynamics, the time-varying random road profile and the tire friction are treated as unknown inputs. To estimate these unknown inputs and states simultaneously, a combination of nonlinear Lipschitz observer and modified super-twisting algorithm (STA) observer is developed. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is established. Simulation results performed with the high-fidelity vehicle simulation software CarSim demonstrate the effectiveness of the proposed scheme in the estimation of states and unknown inputs.</P>
Active Control of Nonlinear Suspension System Using Modified Adaptive Supertwisting Controller
Rath, Jagat J.,Veluvolu, Kalyana C.,Defoort, Michael Hindawi Limited 2015 Discrete dynamics in nature and society Vol.2015 No.-
<P>The suspension system is faced with nonlinearities from the spring, damper, and external excitations from the road surface. The objective of any control action provided to the suspension is to improve ride comfort while ensuring road holding for the vehicle. In this work, a robust higher order sliding mode algorithm combining the merits of the modified supertwisting algorithm and the adaptive supertwisting algorithm has been proposed for the nonlinear active suspension system. The proposed controller is robust to linearly growing perturbations and bounded uncertainties. Simulations have been performed for different classes of road excitations and the results are presented.</P>
Higher-Order Sliding Mode Observer for Speed and Position Estimation in PMSM
Kommuri, Suneel K.,Veluvolu, Kalyana C.,Defoort, M.,Soh, Yeng C. Hindawi Limited 2014 Mathematical problems in engineering Vol.2014 No.-
<P>This paper presents a speed and position estimation method for the permanent magnet synchronous motor (PMSM) based on higher-order sliding mode (HOSM) observer. The back electromotive forces (EMFs) in the PMSM are treated as unknown inputs and are estimated with the HOSM observer without the need of low-pass filter and phase compensation modules. With the estimation of back EMFs, an accurate estimation of speed and rotor position can be obtained. Further, the proposed method completely eliminates chattering. Experimental results with a 26 W three-phase PMSM demonstrate the effectiveness of the proposed method.</P>
Suneel K. Kommuri,Jagat J. Rath,Kalyana C. Veluvolu,M. Defoort 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
This paper presents fault-tolerant cruise control of an electric vehicle based on the permanent magnet synchronous motor (PMSM). A higher order sliding mode (HOSM) observer is designed to estimate the unknown back electro motive forces (EMFs) in the plant dynamics. A finite-time smooth estimation without low-pass filtering is obtained and the chattering phenomenon is eliminated. With the estimated back EMFs, an accurate speed estimate of PMSM can be algebraically computed. The estimated speed is provided as a feedback whenever fault occurs in the measurement speed. The corresponding torque output drives the electric vehicle (train, car) to maintain the vehicle speed to a desired vehicle speed reference. Simulations in a high fidelity CarSim confirm the validity of the overall approach.