Road Vehicle Dynamics: Antilock-Braking System (ABS) Control Systems (Literature Review)

Road Vehicle Dynamics: Antilock-Braking System (ABS) Control Systems
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Road Vehicle Dynamics: Antilock-Braking System (ABS) Control Systems (Literature Review)
Introduction
Safety anti-skid braking systems such as anti-lock braking systems (ABS) are installed in most modern vehicles such as buses, trucks, cars, and motorcycles. The systems work based on a simple mechanism of preventing wheels from locking when braking. This maintains the tractive contact between the wheels and the surface of the road thus allowing the driver or operator to have more control over the automobile. Before the widespread of ABS, skilled drivers employed the techniques of cadence braking and threshold braking, which are now a feature in ABS control systems. However, ABS control systems operate faster than skilled drivers and are more effective. While there are many different methods for ABS control, they differ in terms of their performance based on road conditions and theoretical principles. The present research deals with methods used in designing ABS control systems as well as the challenges and latest developments in control techniques. Like fuzzy control, intelligent control systems in ABS control can emulate the qualitative scenarios of human knowledge, although this can be achieved with additional qualities such as universal approximation theorem, robustness, and rule-based algorithms (Aly et al., 2011). In traditional ABSs, pneumatic or hydraulic pressure brakes are often used. Khan, Hussain, and Shah (2019) have proposed the use of magnetic damping to overcome the challenges of the application of friction used in converting kinetic energy to heat in modern ABS. The application of magnetic damping would reduce thermal failures of the ABS during contract movement, reduce limitations of braking performance especially when at high speed, brake, and noise, and decrease the total time it takes to build up pressure. This paper reviews the literature on an effective method of designing ABS control systems using magnetic damping to regulate slip, reduce stopping distance, and ultimately enhance safety. In demonstrating this improvement, the final project will use MATLAB® and Simulink® to model and simulate braking systems under different damping conditions.
Literature Review
Braking converts the kinetic energy of the moving vehicle into thermal energy to produce friction, and this is the most important concern in today’s automobiles. However, the application of braking causes the locking of the wheels and skidding. To prevent this problem, ABS is designed to help the driver to take control of the steering during hard braking. This prevents locking and skidding of the wheels as well as reducing the stopping distance. Without the ABS, it becomes impossible to stop the car from spinning due to the wheel lockup during hard braking conditions, especially on slippery surfaces. It is estimated that 77 percent of accident cases in the world are due to the problem of wheel skidding while 19 percent are caused by stopping distance (Gahtori, Bharti, & Kumar, 2015). Most modern ABS are used with magnetic damping since conventional ABSs apply friction in the conversion of kinetic energy into thermal energy. This causes problems such as thermal failure of the braking system during contract movement, time is taken to build up pressure, noise, limitation of braking performance during high speeds, and wearing of the brake pads (Khan et al., 2017). This section is a review of literature on the use of magnetic damping in ABS while considering other improvements that have been made to the systems to reduce accidents and enhance safety on roads. A review of Aly, Zeidan, Hamed, and Salem's (2011) work provides general background and a technical understanding of the ABS that have become common in modern vehicles. While this paper is based on magnetic damping in ABS, X. Liu and C. Liu (2013) offer an insight into the brake performance using Eddy current and electrohydraulic hybrid systems. Finally, Khan, Hussain, and Shah (2018) take a closer look at the design and simulation of ABS using the electromagnetic damping systems and conclude on their efficiency in braking.
Aly, Zeidan, Hamed, and Salem (2011) recognize the different control methods that have been developed for ABS that differ in terms of performance and theoretical aspects under different road conditions. The authors review different methods used to design the ABS and identify the main challenges with such methods. More recent developments in the control techniques are summarized. In their paper, the use of ABS control in emulating the qualitative aspects of human intelligence, such as intelligent control systems in fuzzy control is acknowledged (Aly, Zeidan, Hamed & Salem, 2011). These intelligent systems offer several advantages over humans such as universal approximation theorem, robustness, and rule-based algorithms. The article begins with the explanation of the principles of the anti-lock brake system and the use of these systems in reducing the braking distance, the driver taking control of the steering, and the prevention of wearing of tires acknowledged (Aly, Zeidan, Hamed & Salem, 2011). Next, the authors examine unique challenges to the designers of the ABS controllers in different aspects. First, there is a need for the controllers to work at an unstable equilibrium for optimal performance. Second, based on the conditions of the roads, there is a possibility of varying in maximum braking torque. Third, while the signal of measuring the tire slippage is critical for the performance of controllers, it is incredibly noisy and uncertain. Fourth, the tire slip ratio on rough roads varies rapidly and significantly because of tire bouncing. Fifth, the braking system displays some transportation delays that may limit the bandwidth of the control system. Lastly, there are changes to the friction coefficient of friction (Aly, Zeidan, Hamed & Salem, 2011). After a review of the above challenges, the authors describe some of the ideas used in soft computing, which is an aspect of ABS control. These ideas include classical control designs, optimal control designs, non-linear control design, robust control, adaptive control, and intelligent control design.
In the design of ABS control systems, the use of hybrid brake systems has become commonplace in recent years. C. Liu and X. Liu (2013) describe an electro-hydraulic braking system (EHB). This is a new conceptual system of hybrid braking that has seen the optimal combination of Eddy current braking system (ECB) and EHB. The main parts of this brake system are; hybrid brake disk, an electromagnetic coil, copper layer, permanent magnet generator (stator coil, permanent magnet, and generator shell) bracket, hydraulic piston, and friction pad. The combination is supported by the fact that the brake disk of EHB has good wear resistance and the brake disk of ECB has good conductivity and both having good heat dissipation performance. This combination has been fronted to have better performance as both the EHB and ECB braking systems complement each other. Four models which are discussed in detail by ( Liu, Liu 2013) have been used to analyze the braking force distribution, which is key in the ABS control strategy. These models are; the eddy current brake model, hydraulic brake model, brake disk model, and wheel force analysis model. The efficiency is then reinforced by equipping a torque sensor to vary and modify the theoretic value of brake torque (Liu, Liu 2013). This article articulates that the main objective of this hybrid control system is to ensure that the wheel slip at an ideal value is maintained so that the car can cover a short distance to stop and the tire can generate both lateral and steering forces. To contain nonlinearity and uncertainties of vehicle and tire model, the article suggests the application of a nonlinear control strategy that is fuzzy theory-based. This means that when ABS is in use, the fuzzy controller will do the tracking of the optimal objective slip ratio and eliminate any possible tracking error which will enhance steady-state response. The ECB and EHB hybrid brake systems are fixed with the HILS system ...