•The controller of GSC and MSC of DFWPG system is designed based on Hamilton realization.•Realizing a rapid response of the dc bus voltage control by output feedback control strategy.•Realizing ...grid-side unit power factor control of doubly-fed wind power generation system.•Comparing with transient response effects of PI control in Matlab/Simulink environment.
With the nonlinear characteristic of doubly-fed wind power generation (DFWPG) system, Hamilton realization based on analytical mechanics plays a significant role in the system problems of stability analysis and controller design. Hamilton system expression of grid-side converter (GSC) and machine-side converter (MSC) is obtained and the stability control is designed with Lagrange theory of analytical mechanics in this paper. Firstly, to obtain the differential equations which satisfy satisfies self-adjoint conditions, coordinate transformations of dynamic equations of GSC and MSC are conducted. The system Hamilton function and Hamilton realization expression are determined based on Euler–Lagrange process and generalized force method. On the basis of feedback control theory the controller is designed, which can make the system tend to be asymptotically stable in the neighborhood of the equilibrium point. With Hessian matrix positive-definite the Hamilton system is determined to be stable. Additionally, within Matlab/Simulink environment, the transient simulation of DFWPG system is carried out and the effectiveness of controller derived in this paper is verified, by comparisons of response effects with PI control and regulation performances under different wind speeds. The rapid response of the dc bus voltage control, grid-side unit power factor control, a maximum capture of wind energy can be realized, using control design process of Hamilton realization. The system analysis and control design process of Hamilton realization have broad prospects of applications and developments.
This paper presents a new approach to semi-autonomous vehicle hazard avoidance and stability control, based on the design and selective enforcement of constraints. This differs from traditional ...approaches that rely on the planning and tracking of paths. This emphasis on constraints facilitates "minimally-invasive" control for human-machine systems; instead of forcing a human operator to follow an automation-determined path, the constraint-based approach identifies safe homotopies, and allows the operator to navigate freely within them, introducing control action only as necessary to ensure that the vehicle does not violate safety constraints. The method evaluates candidate homotopies based on "restrictiveness", rather than traditional measures of path goodness, and designs and enforces requisite constraints on the human's control commands to ensure that the vehicle never leaves the controllable subset of a desired homotopy. Identification of these homotopic classes in off-road environments is performed using geometric constructs. The goodness of competing homotopies and their associated constraints is then characterized using geometric heuristics. Finally, input limits satisfying homotopy and vehicle dynamic constraints are enforced using threat-based feedback mechanisms to ensure that the vehicle avoids collisions and instability while preserving the human operator's situational awareness and mental models. The methods developed in this work are shown in simulation and experimentally demonstrated in safe, high-speed teleoperation of an unmanned ground vehicle.
Our laboratory has recently described a stability control region in the two-stranded α-helical coiled-coil α-tropomyosin that accounts for overall protein stability but is not required for folding ...(Hodges et al., 2009). We have used a synthetic peptide approach to investigate three stability control sites within the stability control region (residues 97–118). Two of the sites, electrostatic cluster 1 (97–104, EELDRAQE) and electrostatic cluster 2 (112–118, KLEEAEK), feature sequences with unusually high charge density and the potential to form multiple intrachain and interchain salt bridges (ionic attractions). A third site (105–111, RLATALQ) features an e position Leu residue, an arrangement known previously to enhance coiled-coil stability modestly. A native peptide and seven peptide analogs of the tropomyosin sequence 85–119 were prepared by Fmoc solid-phase peptide synthesis. Thermal stability measurements by circular dichroism (CD) spectroscopy revealed the following Tm values for the native peptide and three key analogs: 52.9°C (Native), 46.0°C (R101A), 45.3°C (K112A/K118A), and 27.9°C (L110A). The corresponding ΔTm values for the analogs, relative to the native peptide, are −6.9°C, −7.6°C, and −25.0°C, respectively. The dramatic contribution to stability made by L110e is three times greater than the contribution of either electrostatic cluster 1 or 2, likely resulting from a novel hydrophobic interaction not previously observed. These thermal stability results were corroborated by temperature profiling analyses using reversed-phase high-performance liquid chromatography (RP-HPLC). We believe that the combined contributions of the interactions within the three stability control sites are responsible for the effect of the stability control region in tropomyosin, with the Leu110e contribution being most critical.
Electronic stability control (ESC) is a vehicle safety system designed to keep vehicles moving in the direction commanded by the driver and thereby prevent loss-of-control crashes. Previous research ...has shown that ESC has been highly effective at reducing road departures related to loss of control. ESC is mandatory in all U.S. passenger vehicles manufactured from model year 2012 onward; by a 2014 estimate, ESC is in approximately one-third of passenger vehicles on the road. The proliferation of ESC may therefore alter benefit-to-cost ratios for roadside barriers. The objective of this analysis was to determine the effect of ESC on fatal crashes with roadside barriers. This objective was a first step toward determining whether ESC reduced the overall rate of crashes with roadside barriers and whether ESC had any effect on impact conditions or injury outcomes in barrier crashes. For cars, ESC reduced the odds of fatal crashes with roadside barriers by about 50% and reduced the odds of fatal rollovers that occurred in association with roadside barriers by about 45%. For light trucks and vans, ESC reduced barrier fatality odds by about 40% and barrier-associated rollover fatality odds by about 55%. By 2028, when an estimated 75% of passenger vehicles will have electronic stability control, ESC will have the potential to prevent about 410 out of an estimated 1,180 possible barrier-related fatalities per year. In the long term, once installed in every U.S. passenger vehicle, ESC could prevent about 550 of those same 1,180 possible barrier-related fatalities each year.
For a distributed drive electric vehicle (DDEV) which is equipped with redundant actuators, allocation control is a key technique. Three different allocation control algorithms are designated with ...fixed efficiency matrix, dynamic efficiency matrix, and direct yaw moment distribution, respectively. All these algorithms are applied in a vehicle stability control system with hierarchical control structure and evaluated from three aspects, namely, control precision, real-time characteristics, and control energy. Comparison results demonstrate that the algorithm with dynamic efficiency matrix has the best comprehensive performance, which is also validated in field tests based on a DDEV equipped with four motors.
▶ A meta-analysis was conducted of 12 studies of the effects of ESC on crashes. ▶ Results indicate that ESC prevents ca. 40% of all crashes involving loss of control. ▶ Multiple vehicle crashes were ...found to be largely unchanged. ▶ Behavioural adaptation is not likely to offset the positive safety effects.
The present study is an update of the meta-analysis by Erke (Erke, A., 2008. Effects of Electronic Stability Control (ESC) on accidents: a review of empirical evidence. Accident Analysis & Prevention, 40 (1), 167–173). Results from 12 studies of the effects of Electronic Stability Control (ESC) on the number of different types of crashes were summarized by means of meta-analysis. The results indicate that ESC prevents about 40% of all crashes involving loss of control. The greatest reductions were found for rollover crashes (−50%), followed by run-off-road (−40%) and single vehicle crashes (−25%). These results are however likely to be somewhat overestimated, especially for non-fatal crashes. Multiple vehicle crashes were found to be largely unchanged. Reductions were found for some types of multiple vehicle crashes. Rear-end collisions are unchanged or may increase. Fatal crashes involving pedestrians, bicycles or animals were found to increase as well. ESC was found to be more effective in preventing fatal crashes than non-fatal crashes. ESC is often found to be more effective in Sports Utility Vehicles (SUVs) than in passenger cars. This may be due to differences between drivers of SUVs and passenger cars. The results from meta-analysis indicate that drivers of ESC-equipped vehicles are likely to be safer drivers than other drivers. All the same, ESC may lead to behavioural adaptation in some cases, but it is not likely that behavioural adaptation offsets the positive safety effects. This may be due to a lack of knowledge about ESC.
This paper proposes a robust nonlinear controller to damp the drivetrain torsional oscillations (DTTOs) of wind turbine generators (WTGs) following large disturbances. The key idea is to integrate a ...nonlinear sliding-mode control (SMC) with an extended state observer. The former allows transforming the WTG nonlinear model into a simple first-order nonlinear system via the sliding-mode function, whereas the latter can accurately estimate the nonlinear part of the transformed system and effectively compensate the large disturbances. Simulation results show that, under various conditions, the proposed controller achieves significantly enhanced robustness and performance over the linearization-based controller and conventional SMC.
In this paper, it is demonstrated that the proposed robust path following controller enhances maneuverability and stability of small electric vehicles (EVs) equipped with in-wheel motors through the ...JSAE-SICE benchmark problem No. 3. In order to achieve high maneuverability, maximum tire force is explicitly considered using octagonal approximation. Verifications are conducted using full vehicle model so that the practical vehicle performance is evaluated. In addition to evaluate the total vehicle performance, we apply the controller to all benchmark scenarios and show its maneuverability and stability of small EV are enhanced.
Dans cet article, le système de contrôle de la stabilité électrique (ESC) et le système de direction assistée par la force motrice (DFAS) sont combinés dans un nouvel algorithme de contrôle coordonné ...pour les véhicules électriques à conduite distribuée. Plus précisément, un facteur de correction ki a été introduit pour modifier la force motrice et des règles de contrôle floues ont été conçues pour différentes postures des véhicules et conditions de changement de voie. Sur cette base, l'auteur a déterminé le cadre de base de l'algorithme de contrôle coordonné. Ensuite, l’algorithme proposé a été vérifié au moyen de tests de simulation et d’expériences sur des véhicules réels. Les résultats montrent que l'algorithme proposé garantit une bonne stabilité et de bonnes performances de direction et qu'il est réalisable pour le contrôle de véhicules électriques à conduite distribuée. This paper combines the electric stability control (ESC) and drive force assisted steering (DFAS) into a novel coordinated control algorithm for distributed driving electric vehicles. Specifically, a correction factor ki was introduced to modify the driving force and fuzzy control rules were designed for different vehicle attitudes and lane change conditions. On this basis, the author determined the basic framework of the coordinated control algorithm. Then, the proposed algorithm was verified through simulation tests and real-vehicle experiments. The results show that the proposed algorithm ensures good stability and steering performance and is feasible for the control of distributed driving electric vehicles.
Abstract
An integrated vehicle dynamics control system which aims to improve vehicle handling and stability by coordinating active front steering (AFS) and dynamic stability control (DSC) subsystems ...is developed in this paper. The DSC subsystem includes driveline-based, brake-based, and driveline plus brake-based DSC subsystems. The influence of varying forward speed and lateral acceleration on the lateral vehicle dynamics is investigated first. The AFS controller, which is used to improve vehicle steerability in the low to mid-range lateral acceleration, and the DSC controller, which manages to maintain vehicle stability during extreme driving situations, are then designed by using the sliding mode control (SMC) technique and phase plane method respectively. Based on the two independently developed controllers, a rule-based integration scheme is proposed to optimize the overall vehicle performance by minimizing interactions between the two subsystems and extending functionalities of individual subsystems. Computer simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and stability.
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