The paper presents a gradient-based algorithm for optimal control of nonlinear multivariable systems with control and state vectors constraints. The algorithm has a backward-in-time recurrent ...structure similar to the backpropagation-through-time algorithm, which is mostly used as a learning algorithm for dynamic neural networks. Other main features of the algorithm include the use of higher order Adams time-discretization schemes, numerical calculation of Jacobians, and advanced conjugate gradient methods for favorable convergence properties. The algorithm performance is illustrated on an example of off-line vehicle dynamics control optimization based on a realistic high-order vehicle model. The optimized control variables are active rear differential torque transfer and active rear steering road wheel angle, while the optimization tasks are trajectory tracking and roll minimization for a double lane change maneuver.
A traction control system (TCS) for two-wheel-drive vehicles can conveniently be realised by means of slip control. Such a TCS is modified in this paper in order to be applicable to four-wheel-drive ...vehicles and anti-lock braking systems, where slip information is not readily available. A reference vehicle model is used to estimate the vehicle velocity. The reference model is excited by a saw-tooth signal in order to adapt the slip for maximum tyre traction performance. The model-based TCS is made robust to vehicle modelling errors by extending it with (i) a superimposed loop of tyre static curve gradient control or (ii) a robust switching controller based on a bi-directional saw-tooth excitation signal. The proposed traction control strategies are verified by experiments and computer simulations.
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The use of advanced dynamic friction models can improve the brush-type tire friction models. This paper presents a 3D dynamic brush model based on the LuGre friction model. The model describes the ...dynamics of longitudinal and lateral tire friction forces, as well as the self aligning torque dynamics. It has been originally derived in a distributed-parameter form, and then transformed to a simpler lumped-parameter form with only three internal states. Both uniform and non-uniform normal pressure distributions are considered. The model has analytical solution for steady-state conditions. The steady-state behavior is validated with respect to "magic" formula static model, which served as an "ideal" benchmark. The lumped model dynamic behavior is validated by comparing its time-responses with original distributed model responses. The model parameterization with respect to normal force and other tire/road parameters is considered as well.
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This paper presents design of an SI engine load torque estimator based on an adaptive Kalman filter. The adaptive estimator is characterized by a fast response and good noise suppression ability. The ...estimator is used to establish a fast load torque compensation path within a proportional-plus-integral (PI) controller-based idle speed control system. The proposed adaptive controller has been verified by means of experiments, and compared with PI, PID and polynomial controllers. The experimental results point out to favorable performance of the adaptive controller for a wide engine operating range.
Wet clutches are widely used in automotive systems. They are essential parts of automatic transmissions, modern All-Wheel-Drive systems or dual-clutch transmissions. Regardless of the area of ...application, a good knowledge of clutch friction behaviors is crucial for the clutch control system development. This paper considers two important factors of the wet clutch dynamics: coefficient of friction behavior and thermal dynamics. An Active Limited Slip Differential wet clutch with carbon fiber-based friction lining material is experimentally characterized by using a precise wet clutch setup. The characterization of the coefficient of friction behavior includes influence of clutch slip speed, applied force, and friction surface temperature. The clutch thermal dynamics is characterized based on the heat power balance law applied to the clutch separator plate with a variable heat transfer coefficient. The results of the thermal model experimental validation are presented, as well.
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The paper shows that, during abrupt wheel torque transients for ice surface and low vehicle speeds, the tyre can develop significantly larger longitudinal force than the peak value of the tyre static ...curve. This so-called dynamic tyre friction potential (DTFP) effect has many influencing factors such as the rate of change of the wheel torque, the vehicle speed, and the tyre dwell time. The paper presents a detailed analysis of the DTFP behaviour based on the experimental data collected by using an in-wheel motor-based tyre test vehicle. The analysis results and an insight into the brush structure of a tyre model lead to the hypothesis that the different influencing factors may be predominantly explained by the bristle dwell time (BDT) effect. Following this hypothesis, the LuGre model of the tyre friction dynamics is extended with a physical BDT sub-model. The experimental validation results show that the proposed model can accurately capture the low-speed tyre-ice friction behaviour during abrupt wheel torque transients.
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This paper presents a survey of the recent research results of the authors in the field of modeling of automotive power train systems and components. The goal of the research is to propose simple and ...accurate power train models for controller design and to propose computationally efficient simulations. The modeling includes typical power train components such as electronic throttle, SI engine, torque converter, planetary gear set, wet clutch, differential, half shaft, and tire. Experimental model validation results are presented
In autonomous vehicles the driver will become a passenger. By ensuring a high level of ride comfort through active suspensions, the driver's ability to perform various tasks such as reading, drawing ...and texting can be enhanced. A high-performance shaker rig can conveniently be used to test the ride comfort improvement by means of various active suspensions under laboratory conditions. The paper deals with the design of such a rig, which employs a linear electric servomotor to impose accurately controlled vertical vibrations of driver seat. The reference time profiles of seat acceleration, velocity and displacement are generated off-line by using a half-car vehicle model and LQR control with a road preview option. The selection of linear motor comes from assessment of three characteristic shaker rig drive designs (hydraulic and two electric ones). To ensure high-precision seat motion, the proposed shaker control system includes: acceleration feedforward and feedback control loops, a state controller-like compensator of accelerometer offset to prevent drift of seat position and velocity, and feedforward compensation of linear motor cogging force mode. The designed shaker rig application is demonstrated through a case study related to ride comfort evaluation of various active suspension configurations and a drawing task. The drawing task results are employed to determine the root-mean-square vertical seat acceleration threshold, below which the active suspension drawing task performance remains similar to that obtained under standstill conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The paper presents results of experimental characterization and modeling of dry clutch material wear, which concerns four input parameters (temperature, slip speed, torque, and closing time) and ...relies on using a custom-made disc-on-disc tribometer machine. A clutch closing cycle-wise cubic model is proposed, where for the sake of model compactness and least-square parameter identification method straightforwardness the torque and slip speed inputs are lumped into a surrogate power input. Finally, the characterization study is extended to concern the fading effect occurring at high clutch temperatures, including the wear restoration dynamics. The high-temperature results are employed to verify model extrapolation capability.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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