The braking system is the main active safety equipment of vehicles. This paper presents a new brake system architecture based on the use of proportional servovalves. The use of servovalves allows for faster and more precise control of the pressure, preventing the wheels from locking and reducing braking distances. A new control block has been developed to determine the optimum pressure in the braking circuit. The new controller is based on the use of fuzzy logic techniques. A Kalman-filter-based estimation algorithm allows for obtaining the adhesion between the wheel and road surface and vehicle speed. These parameters are used in a fuzzy block to detect the road type. Using the road type, an artificial neural network gives an estimation of the slip that produces higher adhesion, and a final block, which is also based on fuzzy logic, determines the optimal pressure in the braking circuit. The performance of the new brake architecture and controller is evaluated by simulating driving on different road surfaces and with real tests on dry and wet asphalt.

A Novel Electrohydraulic Brake System With Tire–Road Friction Estimation and Continuous Brake Pressure Control

A tire's torsional dynamics couple the responses of wheel/hub inertia to that of the ring/belt inertia. Depending on the effective stiffness, damping, and mass distribution of the tire, the ensuing deflections between the wheel and the ring can cause significant errors in the estimation of the tire's longitudinal slip from wheel speed measurements. However, this remains the established approach for constructing anti-lock braking system (ABS) control algorithms. Under aggressive braking events, the errors introduced by torsional dynamics may significantly affect the ABS algorithm and result in less than optimal braking performance. This article investigates the interaction of tire torsional dynamics and ABS control using a comprehensive system model that incorporates sidewall flexibility, transient and hysteretic tread-ground friction effects, and the dominant dynamics of a hydraulic braking system. It considers a wheel/hub acceleration-based ABS controller that mimics the working steps of a comm...

Interaction of Anti-lock Braking Systems with Tire Torsional Dynamics

In real-time safety-critical systems, it is important to predict the impact of faults on their operation. For this purpose we have developed a test bed based on software implemented fault injection (SWIFI). Faults are simulated by disturbing the states of registers and memory cells. Analyzing reactive and embedded systems with SWIFI tools is a new challenge related to the simulation of an external environment for the system, designing test scenarios and result qualification. The paper presents our original approach to these problems verified for an ABS microcontroller. We show fault susceptibility of the ABS microcontroller and outline software techniques to increase fault robustness.

Analyzing Fault Susceptibility of ABS Microcontroller

An Investigation of Anti-lock Braking System for Automobiles

The paper deals with the problem of adapting software implemented fault injection technique (SWIFI) to evaluate dependability of reactive microcontroller systems. We present an original methodology of disturbing controller operation and analyzing fault effects taking into account reactions of the controlled object and the impact of the system environment. Faults can be injected randomly (in space and time) or targeted at the most sensitive elements of the controller to check it at high stresses. This approach allows identifying rarely encountered problems, usually missed in classical approaches. The developed methodology has been used successfully to verify dependability of ABS system. Experimental results are commented in the paper.

Testing Distributed ABS System with Fault Injection

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KZ Kiril Rangelov

Papers

SIMULINK model of a quarter-vehicle with an Anti-lock Braking System