The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Masayoshi Tomizuka - One of the best experts on this subject based on the ideXlab platform.
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linear parameter varying controller for automated lane guidance experimental study on tractor trailers
IEEE Transactions on Control Systems and Technology, 2002Co-Authors: P. Hingwe, Andrew Packard, Hanshue Tan, Masayoshi TomizukaAbstract:Proposes a linear parameter-varying (LPV) controller design for automated lane keeping for vehicles. The lane keeping objective is to keep the vehicle centered with respect to the lane boundaries by applying appropriate steering action. Most current implementation of lane keeping controllers were based on linear synthesis techniques because linear techniques offer a direct tradeoff between steering action, passenger comfort, robustness, and tracking performance. However, linear methods assume constant Longitudinal Velocity of the vehicle for controller synthesis. It is known that the position response of the vehicle to the steering input varies significantly with the Longitudinal Velocity of the vehicle. The LPV design technique deals with this issue by synthesizing a Velocity dependent controller. The controller minimizes the induced /spl Lscr//sub 2/ norm of the closed loop from the road curvature to the tracking error. The design has been successfully implemented on a tractor-trailer vehicle and experiments conducted up to Longitudinal Velocity of 60 mi/h are presented.
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Robust Longitudinal Velocity tracking of vehicles using traction and brake control
6th International Workshop on Advanced Motion Control Proceedings, 2000Co-Authors: M. Tai, Masayoshi TomizukaAbstract:Vehicle Longitudinal control is an essential part of advanced vehicle control systems. The paper is concerned with robust Longitudinal Velocity tracking of vehicles using traction control and brake control. First, a Longitudinal vehicle model is introduced both for traction and braking modes. Then, for each mode, a robust Velocity tracking controller is designed based on backstepping. At each step of constructing a candidate Lyapunov function, a scaling parameter is introduced for each added term to take into account badly scaled system states. The concepts of effective traction mass and effective braking mass are introduced in the vehicle Longitudinal model such that the derived model is applicable to any types of traction and braking configuration of the vehicles. The designed controller is proved to be effective by simulation.
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Linear parameter varying controller for automated lane guidance experimental study on tractor semi-trailers
Proceedings of the 2000 American Control Conference. ACC (IEEE Cat. No.00CH36334), 2000Co-Authors: P. Hingwe, Andrew Packard, Masayoshi TomizukaAbstract:Proposes a linear parameter varying (LPV) controller design for automated lane keeping for vehicles. The lane keeping objective is to keep a point on the vehicle centered with respect to the lane boundaries by applying appropriate steering action. It is known that the position response of the vehicle to the steering input varies significantly with the Longitudinal Velocity of the vehicle. The LPV design technique allows for the controller to be a continuous function of Longitudinal Velocity. The controller minimizes the induced /spl Lscr//sub 2/ norm of the closed loop from the road curvature to the tracking error. The design has been implemented on a tractor semi-trailer vehicle and experiments conducted up to Longitudinal Velocity of 55 MPH (legal speed limit for tractor semi-trailer vehicles in California) are presented.
Yingmin Jia - One of the best experts on this subject based on the ideXlab platform.
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Precompensation decoupling control with H∞ performance for 4WS Velocity-varying vehicles
International Journal of Systems Science, 2016Co-Authors: Yingmin JiaAbstract:ABSTRACTIn this paper, a new decoupling control strategy with H∞ performance for the three-degree-of-freedom model, including the Longitudinal Velocity, the lateral Velocity, and the yaw rate is presented and discussed. A sliding mode controller only depending on the Longitudinal Velocity for the Longitudinal system and a precompensation decoupling controller with H∞ performance for the steering system are designed. These controllers are established by feeding back Longitudinal Velocity and yaw rate, thus observation or measurement for the lateral Velocity is not required. Simulation results show that our strategy can improve the handling characteristics, safety, and comfort significantly.
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Decoupling control in Velocity-varying four-wheel steering vehicles with H∞ performance by Longitudinal Velocity and yaw rate feedback
Vehicle System Dynamics, 2014Co-Authors: Yingmin JiaAbstract:In this paper, decoupling control with H∞ performance for four-wheel steering (4WS) vehicles under varying Longitudinal Velocity is studied. A novel control scheme for a nonlinear model of three states, respectively, the Longitudinal and lateral velocities, and yaw rate, is proposed to address this issue. The scheme is composed of two varying-parameter controllers designing problems for both Longitudinal and lateral systems with coupling performance. Varying parameters of both these controllers depend only on Longitudinal Velocity. Controlled by these controllers, the Longitudinal system is decoupled with lateral Velocity and yaw rate, and the lateral system is input–output decoupling with H∞ performance. In addition, feedback signals are the Longitudinal Velocity and yaw rate, hence observations or measurements of lateral Velocity are not necessary. Simulations show that vehicles controlled by our scheme are input–output diagonal decoupling and execute very well while Longitudinal Velocity varies in a la...
Hossein Bonakdari - One of the best experts on this subject based on the ideXlab platform.
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comparative assessment of the hybrid genetic algorithm artificial neural network and genetic programming methods for the prediction of Longitudinal Velocity field around a single straight groyne
Applied Soft Computing, 2017Co-Authors: Akbar Safarzadeh, Amir Hossein Zaji, Hossein BonakdariAbstract:Abstract In the present paper, three-dimensional flow fields around single straight groynes with various lengths have been discussed. The dataset of the flow field is measured in the laboratory using Acoustic Doppler Velocimeter (ADV). Then, the Longitudinal Velocity field is modelled using a novel hybrid method of Genetic Algorithm based artificial neural network (GAA) that has the ability to automatically adjust the number of hidden neurons. To investigate the proposed method’s performance, the results of GAA is measured and compared with one of the most common genetic algorithm based prediction method, namely genetic programming (GP). It is concluded that that GAA model successfully simulates the complex Velocity field, and both the Velocity magnitudes and isovel shapes are well predicted by this model. The results show that GAA with RMSE of 0.1236 in test data has a significantly better performance than the GP model with RMSE of 0.2342. In addition, it was founded that the transverse coordinate of the measuring point (Y*) is the most important input variable.
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Comparative Assessment of the Hybrid Genetic Algorithm–Artificial Neural Network and Genetic Programming Methods for the Prediction of Longitudinal Velocity Field around a Single Straight Groyne
Applied Soft Computing, 2017Co-Authors: Akbar Safarzadeh, Amir Hossein Zaji, Hossein BonakdariAbstract:Abstract In the present paper, three-dimensional flow fields around single straight groynes with various lengths have been discussed. The dataset of the flow field is measured in the laboratory using Acoustic Doppler Velocimeter (ADV). Then, the Longitudinal Velocity field is modelled using a novel hybrid method of Genetic Algorithm based artificial neural network (GAA) that has the ability to automatically adjust the number of hidden neurons. To investigate the proposed method’s performance, the results of GAA is measured and compared with one of the most common genetic algorithm based prediction method, namely genetic programming (GP). It is concluded that that GAA model successfully simulates the complex Velocity field, and both the Velocity magnitudes and isovel shapes are well predicted by this model. The results show that GAA with RMSE of 0.1236 in test data has a significantly better performance than the GP model with RMSE of 0.2342. In addition, it was founded that the transverse coordinate of the measuring point (Y*) is the most important input variable.
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Application of artificial neural network and genetic programming models for estimating the Longitudinal Velocity field in open channel junctions
Flow Measurement and Instrumentation, 2015Co-Authors: Amir Hossein Zaji, Hossein BonakdariAbstract:Abstract Estimating the accurate Longitudinal Velocity fields in an open channel junction has a great impact on hydraulic structures such as irrigation and drainage channels, river systems and sewer networks. In this study, Genetic Programming (GP) and Multi-Layer Perceptron Artificial Neural Network (MLP-ANN) were modeled and compared to find an analytical formulation that could present a continuous spatial description of Velocity in open channel junction by using discrete information of laboratory measurements. Three direction coordinates of each point of the fluid flow and discharge ratio of main to tributary channel were used as inputs to the GP and ANN models. The training and testing of the models were performed according to the published experimental data from the related literature. To find the accurate prediction ability of GP and ANN models in cases with minor training dataset, the models were compared with various percents of allocated data to train dataset. New formulations were obtained from GP and ANN models that can be applied for practical Longitudinal Velocity field prediction in an open channel junction. The results showed that ANN model by Root Mean Squared Error (RMSE) of 0.068 performs better than GP model by RMSE of 0.162, and that ANN can model the Longitudinal Velocity field with small population of train dataset with high accuracy.
R. A. Antonia - One of the best experts on this subject based on the ideXlab platform.
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Finite Reynolds number effect on the scaling range behaviour of turbulent Longitudinal Velocity structure functions
Journal of Fluid Mechanics, 2017Co-Authors: S. L. Tang, R. A. Antonia, L. Djenidi, L. Danaila, Y. ZhouAbstract:The effect of large-scale forcing on the second- and third-order Longitudinal Velocity structure functions, evaluated at the Taylor microscale r A. is assessed in various turbulent flows at small to moderate values of the Taylor microscale Reynolds number RA. It is found that the contribution of the large-scale terms to the scale by scale energy budget differs from flow to flow. For a fixed RA, this contribution is largest on the centreline of a fully developed channel flow but smallest for stationary forced periodic box turbulence. For decaying-type flows, the contribution lies between the previous two cases. Because of the difference in the large-scale term between flows, the third-order Longitudinal Velocity structure function at r = A differs from flow to flow at small to moderate RA. The effect on the second-order Velocity structure functions appears to be negligible. More importantly, the effect of RA on the scaling range exponent of the Longitudinal Velocity structure function is assessed using measurements of the streamwise Velocity fluctuation ii, with RA in the range 500-1100, on the axis of a plane jet. It is found that the magnitude of the exponent increases as RA increases and the rate of increase depends on the order ii. The trend of published structure function data on the axes of an axisymmetric jet and a two-dimensional wake confirms this dependence. For a fixed RA, the exponent can vary from flow to flow and for a given flow, the larger RA is, the closer the exponent is to the value predicted by Kolmogorov (Dok!. Akad. Nauk SSSR, vol. 30, 1941a, pp. 299-303) (hereafter K41). The major conclusion is that the finite Reynolds number effect, which depends on the flow, needs to he properly accounted for before determining whether corrections to K41, arising from the intermittency of the energy dissipation rate, are needed. We further point out that it is imprudent, if not incorrect, to associate the finite Reynolds number effect with a consequence of the modified similarity hypothesis introduced by Kolmogorov (J. Fluid Mech., vol. 13, 1962, pp. 82-85) (K62); we contend that this association has misled the vast majority of post K62 investigations of the consequences of K62.
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Scaling of mixed Longitudinal Velocity-temperature structure functions
Europhysics Letters (EPL), 2000Co-Authors: R. A. Antonia, Sundara RajagopalanAbstract:Measurements in a turbulent round jet at a moderately high Taylor microscale Reynolds number Rλ indicate that the mixed structure functions of u, the Longitudinal Velocity fluctuation, and θ, the temperature fluctuation, show a smaller departure from the Kolmogorov (1941)-Obukhov (1949) scaling than either the Velocity or temperature structure functions at the same order. This reduced anomalous scaling indicates that the Velocity and temperature increments are not statistically independent, as is reflected by the non-negligible correlation between Velocity and temperature increments. The scaling exponents of both the temperature structure functions and the mixed u-θ structure functions increase with Rλ.
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Scaling of Longitudinal Velocity increments in a fully developed turbulent channel flow
Physics of Fluids, 1998Co-Authors: R. A. Antonia, Paolo Orlandi, Giovanni Paolo RomanoAbstract:The departure from Kolmogorov (1941) scaling of high-order moments of Longitudinal Velocity increments in a fully developed turbulent channel flow is investigated using data obtained with hot wire anemometry (HWA), laser Doppler velocimetry (LDV) and direct numerical simulation (DNS). The magnitude of the departure increases towards the wall, reaching a local maximum at a distance of about 20 wall units.
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Second- and third-order Longitudinal Velocity structure functions in a fully developed turbulent channel flow
Physics of Fluids, 1997Co-Authors: R. A. Antonia, Tongming Zhou, Giovanni Paolo RomanoAbstract:Second- and third-order moments of temporal increments of the Longitudinal Velocity fluctuation have been measured using hot wires in a fully developed turbulent channel flow and analyzed using values of the mean energy dissipation rate inferred from direct numerical simulation data for the same flow and Reynolds numbers. The results indicate that dissipative range scales approach isotropy relatively rapidly when the mean shear is negligible. For larger inertial range type scales, the approach is slower. The rate at which isotropy is approached seems slower for third-order than second-order structure functions. This rate depends more on the mean shear than on the turbulent Reynolds number. Two-point laser Doppler anemometry measurements provide reasonable support for the use of Taylor’s hypothesis, at least outside the buffer region.
P. Hingwe - One of the best experts on this subject based on the ideXlab platform.
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linear parameter varying controller for automated lane guidance experimental study on tractor trailers
IEEE Transactions on Control Systems and Technology, 2002Co-Authors: P. Hingwe, Andrew Packard, Hanshue Tan, Masayoshi TomizukaAbstract:Proposes a linear parameter-varying (LPV) controller design for automated lane keeping for vehicles. The lane keeping objective is to keep the vehicle centered with respect to the lane boundaries by applying appropriate steering action. Most current implementation of lane keeping controllers were based on linear synthesis techniques because linear techniques offer a direct tradeoff between steering action, passenger comfort, robustness, and tracking performance. However, linear methods assume constant Longitudinal Velocity of the vehicle for controller synthesis. It is known that the position response of the vehicle to the steering input varies significantly with the Longitudinal Velocity of the vehicle. The LPV design technique deals with this issue by synthesizing a Velocity dependent controller. The controller minimizes the induced /spl Lscr//sub 2/ norm of the closed loop from the road curvature to the tracking error. The design has been successfully implemented on a tractor-trailer vehicle and experiments conducted up to Longitudinal Velocity of 60 mi/h are presented.
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Linear parameter varying controller for automated lane guidance experimental study on tractor semi-trailers
Proceedings of the 2000 American Control Conference. ACC (IEEE Cat. No.00CH36334), 2000Co-Authors: P. Hingwe, Andrew Packard, Masayoshi TomizukaAbstract:Proposes a linear parameter varying (LPV) controller design for automated lane keeping for vehicles. The lane keeping objective is to keep a point on the vehicle centered with respect to the lane boundaries by applying appropriate steering action. It is known that the position response of the vehicle to the steering input varies significantly with the Longitudinal Velocity of the vehicle. The LPV design technique allows for the controller to be a continuous function of Longitudinal Velocity. The controller minimizes the induced /spl Lscr//sub 2/ norm of the closed loop from the road curvature to the tracking error. The design has been implemented on a tractor semi-trailer vehicle and experiments conducted up to Longitudinal Velocity of 55 MPH (legal speed limit for tractor semi-trailer vehicles in California) are presented.
