An antilock braking system (ABS) is one of the most effective active safety control systems for ground vehicles, since it can keep the rotational wheel from locking and, consequently, guarantee the ...braking safety and handling stability. There have been a variety of ABS control schemes proposed by many researchers. However, most of the results employ sundry tire-road friction models, the alleged <inline-formula><tex-math notation="LaTeX">\mu\, \text{--}\,\lambda</tex-math></inline-formula> curves (<inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula> is the tire-road friction coefficient, while <inline-formula><tex-math notation="LaTeX">\lambda</tex-math></inline-formula> is the tire slip ratio, which is mathematically defined as <inline-formula><tex-math notation="LaTeX">\lambda =({v-\omega r})/{v}</tex-math></inline-formula>), making the ABS controller extremely complicated for the highly nonlinear characteristics of the <inline-formula><tex-math notation="LaTeX">\mu\, \text{--}\,\lambda</tex-math></inline-formula> relationship. Furthermore, the a priori knowledge of road conditions for these ABS controllers restricts their practicability. To circumvent these problems, a two-time-scale ABS control scheme is proposed in this paper, without considering the intricate <inline-formula><tex-math notation="LaTeX">\mu\, \text{--}\,\lambda</tex-math></inline-formula> relationship, making the a priori knowledge of the road condition no longer a prerequisite; thus, the designed ABS controller is rather simple. In addition, a modified fast-time-scale estimator is involved to estimate the road condition, which is significant in vehicle active dynamics control. The effectiveness of the proposed ABS controller is verified via numerical simulations and CarSim-MATLAB cosimulations.
This paper addresses the development and Hardware-in-the-Loop (HiL) testing of an explicit nonlinear model predictive controller (eNMPC) for an antilock braking system (ABS) for passenger cars, ...actuated using an electro-hydraulic braking unit. The control structure includes a compensation strategy to guard against the performance degradation due to actuation dead times, identified by experimental tests. The eNMPC is run on an automotive rapid control prototyping unit, which shows its real-time capability with comfortable margin. A validated high-fidelity vehicle simulation model is used for the assessment of the ABS on a HiL rig equipped with the braking system hardware. The eNMPC is tested in seven emergency braking scenarios, and its performance is benchmarked against a proportional-integral-derivative (PID) controller. The eNMPC results show: 1) the control system robustness with respect to the variations in tire-road friction condition and initial vehicle speed; and 2) consistent and significant improvement of the stopping distance and wheel slip reference tracking, with respect to the vehicle with the PID ABS.
Since their introduction, anti-lock braking systems (ABS) have mostly relied on heuristic, rule-based control strategies. ABS performance, however, can be significantly improved thanks to many recent ...technological developments. This work presents an extensive review of the state of the art to verify such a statement and quantify the benefits of a new generation of wheel slip control (WSC) systems. Motivated by the state of the art, as a case study, a nonlinear model predictive control (NMPC) design based on a new load-sensing technology was developed. The proposed ABS was tested on Toyota's high-end vehicle simulator and was benchmarked against currently applied industrial controller. Additionally, a comprehensive set of manoeuvres were deployed to assess the performance and robustness of the proposed NMPC design. The analysis showed substantial reduction of the braking distance and better steerability with the proposed approach. Furthermore, the proposed design showed comparable robustness against external factors to the industrial benchmark.
This paper presents a regenerative anti-lock braking system control method with road detection capability. The aim of the proposed methodology is to improve electric vehicle safety and energy economy ...during braking maneuvers. Vehicle body longitudinal deceleration is used to estimate a road surface. Based on the estimation results, the controller generates an appropriate braking torque to keep an optimal for various road surfaces wheel slip and to regenerate for a given motor the maximum possible amount of energy during vehicle deceleration. A fuzzy logic controller is applied to fulfill the task. The control method is tested on a four in-wheel-motor drive sport utility electric vehicle model. The model is constructed and parametrized according to the specifications provided by the vehicle manufacturer. The simulation results conducted on different road surfaces, including dry, wet and icy, are introduced.
The driving motor of the electric vehicle (EV) can recover the kinetic energy during normal braking maneuvers by a regenerative function. At the same time, its dynamic torque response proves to be ...accurate and fast for an emergency braking, namely an anti-lock braking, with the coordinated control of the frictional braking system. However, vehicle transmission properties will deteriorate the control performance of the motor, especially in the anti-lock braking process. A novel permanent magnet synchronous motor (PMSM) control method is proposed considering the transmission influence on this high-dynamic braking process of the pure EV. First, the EV's dynamic model, which includes the PMSM field-oriented control model, the transmission dynamic model, and the hydraulic braking system, is built, and the influences of transmission elasticity and backlash non-linearity on the motor-braking torque are analyzed. Then, based on the wheel slip ratio target of the anti-lock braking, the novel mode-switching method for the motor-torque control between the backlash sliding-mode compensation and the elasticity double-closed-loop PID compensation is put forward. Two state-of-the-art anti-lock braking algorithms, which simplify the transmission properties, the slip ratio phase-plane theory, and the sliding-mode control, are compared with the proposed method. Simulation and test-bench experiment results show that, on different test-road surfaces, the mode-switching PMSM control can effectively compensate for transmission effects and significantly improve the EV's anti-lock braking comfort, stability, and maneuverability with fast and accurate motor-torque regulating.
In this article, the problem of control of antilock braking systems under significant uncertainties and unknown relationship between tire-road friction coefficient and wheel slip ratio for a two-axle ...vehicle model is considered. Two methods based on a disturbance observer and sliding mode control are proposed. In the first method, a conventional sliding surface is used while in the second method a new nonlinear sliding surface is proposed as an improvement over the first method. The performance under the proposed methods is assessed analytically and by MATLAB simulation under different road conditions. The proposed methods are validated further on CarSim platform.
Wheel slip control for ground vehicles with individually controlled electric motors can be realized with strategies that can significantly differ from the conventional antilock braking system (ABS) ...and traction control (TC) system. This paper provides a review of state-of-the-art technology and recent developments in TC and ABSs using the actuation of electric motors. Particular attention is paid to the realization of slip estimators, the formalization of torque demand, and the control methods applied for the implementation of TC and ABSs. The performed analysis allowed for the differentiation of several most elaborated methods for slip and torque control and defining still imperfectly investigated problems to be covered by the further development of TC and ABSs for full electric vehicles.
An antilock braking system (ABS) is one of the most important components in a road vehicle, which provides active protection during braking, to prevent the wheels from locking-up and achieve handling ...stability and steerability. The all-electric ABS without any hydraulic components is a potential candidate for electric vehicles. To demonstrate and examine the all-electric ABS algorithms, this article proposes a single-wheel all-electric ABS test bench, which mainly includes the vehicle wheel, the roller, the flywheels, and the electromechanical brake. To simulate dynamic operation of a real vehicle’s wheel, the kinetic energy of the total rotary components in the bench is designed to match the quarter of the one of a commercial car. The vertical force to the wheel is adjustable. The tire-roller contact simulates the real tire-road contact. The roller’s circumferential velocity represents the longitudinal vehicle velocity. The design and analysis of the proposed bench are described in detail. For the developed prototype, the rated clamping force of the electromechanical brake is 11 kN, the maximum vertical force to the wheel reaches 300 kg, and the maximum roller (vehicle) velocity reaches 100 km/h. The measurable bandwidth of the wheel speed is 4 Hz–2 kHz and the motor speed is 2.5 Hz–50 kHz. The measured results including the roller (vehicle) velocity, the wheel velocity, and the wheel slip are satisfactory. This article offers the effective tools to verify all-electric ABS algorithms in a laboratory, hence saving time and cost for the subsequent test on a real road.
Where Do Batteries End and Supercapacitors Begin? Simon, Patrice; Gogotsi, Yury; Dunn, Bruce
Science (American Association for the Advancement of Science),
03/2014, Volume:
343, Issue:
6176
Journal Article
Peer reviewed
Open access
Electrochemical measurements can distinguish between different types of energy storage materials and their underlying mechanisms.
Batteries keep our devices working throughout the day–that is, they ...have a high energy density–but they can take hours to recharge when they run down. For rapid power delivery and recharging (i.e., high power density), electrochemical capacitors known as supercapacitors (
1
) are used. One such application is regenerative braking, used to recover power in cars and electric mass transit vehicles that would otherwise lose braking energy as heat. However, supercapacitors have low energy density.
This paper mainly focuses on control strategy of the regenerative braking system of an electric vehicle under safety critical driving situations. With the aims of guaranteeing the electric vehicle ...stability in various types of tire-road adhesion conditions, based on the characteristics of an electrified powertrain, a novel control strategy of regenerative braking system is proposed for electric vehicles during anti-lock braking procedures. Firstly, the main construction of the case-study electric car with regenerative braking system is introduced. Next, based on the phase plane theory, the optimal brake torque is calculated for ABS control of an electric vehicle. Then, an allocation control, wherein the required optimal brake torque is divided into two parts that are disposed respectively by the friction and regenerative brakes, is discussed. In addition, two parameters for evaluating regeneration braking energy efficiency contribution while in the deceleration braking process are defined. Furthermore, a novel regenerative braking control strategy named “serial control strategy” is proposed. Finally, the road tests are implemented in four types of tire-road adhesion conditions under safety-critical driving situations. The test results validate the effectiveness and feasibility of the proposed control strategy.
•A new control strategy of regenerative braking system for electric vehicles is proposed.•Design of the regenerative braking system is introduced.•Two different evaluation parameters for regenerative breaking energy efficiency contribution are defined.•The control strategy and evaluation parameters are verified by road test results.
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