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Journal Article

Advancement of Vehicle Dynamics Control with Monitoring the Tire Rolling Environment

One of the most important challenges for electronic stability control (ESC) systems is the identification and monitoring of tire rolling environment, especially actual tire-road friction parameters. The presented research considers an advanced variant of the ESC system deducing the mentioned factors based on intelligent methods as fuzzy sets. The paper includes: Overview of key issues in prototyping the algorithms of Electronic Stability Control. Case study for vehicle model. Procedures for monitoring of tire rolling environment: theoretical backgrounds, computing methods, fuzzy input and output variables, fuzzy inference systems, interface with ESC algorithm. Case study for ESC control algorithm. Examples of simulation using Hardware-in-the-Loop procedures. The proposed approach can be widely used for the next-generation of ESC devices having the close integration with Intelligent Transport Systems.
Technical Paper

Comparison of Different Methods for the Determination of the Friction Temperature of Disc Brakes

In the paper the dynamometer investigations on evaluating of friction temperature in disc brakes have been described. The goal of these investigations was to compare different methods (thermocouples, pyrometers and thermoscanner) regarding to their accuracy and suitability for specified test procedures. The problems of the evaluation and the changing of the disc surface emissivity and a way of its correction have also been discussed. Furthermore the possibilities of non-contact measuring methods for the evaluation of non-homogeneous temperature distribution over the disc surface under various braking conditions have been shown.
Technical Paper

Simulation of Brake Control for Motorcycles

Development of anti-lock brake system (ABS) for motorcycles needs specific approaches to the control of movement of a wheel. The well developed ABS control principles for cars or trucks cannot be automatically applied to motorcycles. In this connection, an alternative strategy of pre-extreme ABS control has been researched and simulated. Its aim is to ensure the wheel operation in pre-extreme, stable area of “coefficient of longitudinal force - wheel slip” dependence. MATLAB software and specially created software have been used for the simulation of single-channel and two-channel ABS systems. This simulation has verified that the pre-extreme ABS algorithm guarantees the high braking efficiency and motorcycle stability consequently.
Technical Paper

Comparison Between Different Investigation Methods of Quasi-Static and Dynamic Brake Pad Behaviour

The paper offers an investigation of whether the knowledge of the laws materials will follow and of the parameters for the materials can be obtained from integral testing, i.e. the testing of complete brake pads. Dynamic tests were designed for the purpose, with attention to both the axial and the radial / tangential directions of stress as mechanical properties of brake pads. The tests were run and evaluated on brake pads with a variety of patterns and constructions. The term used throughout this paper to describe these features is the matrix. It was shown that brake pads clearly demonstrate visco-elastic behaviour which is most definitely non-linear, and whose characteristic values for stiffness, damping and internal friction will alter in ratio to the load.
Technical Paper

Mojacar Brake Wear and NVH: Dyno Simulation Concept

Efficient development and testing of brake systems requires further substitution of expensive and time consuming vehicle testing by appropriate dynamometer testing. Some of the current simulation methods do not reflect the needs of engineering and the progress made in the development of test equipment. The lack of suitable procedures may cause unexpected delays in the realization of projects. Road load simulations for lifetime prediction on brake dynamometers have a long history, however never got a real break-through in Europe - possibly because the prediction quality and efficiency did not satisfy. This paper concentrates first on the analysis of the vehicle data recorded in Mojacar (Spain) which is a sign-off test for wear and noise for brands of Ford Motor Company for European market. Specific attention is given to different types of driving resistances and road profiles and to consideration of different methods for numerical description and comparison of road load data.
Journal Article

Experimental Study on Continuous ABS Operation in Pure Regenerative Mode for Full Electric Vehicle

Anti-lock braking functions of electric vehicles with individual wheel drive can be effectively realized through the operation of in-wheel or on-board motors in the pure regenerative mode or in the blending mode with conventional electro-hydraulic anti-lock braking system (ABS). The regenerative ABS has an advantage in simultaneous improvement of active safety, energy efficiency, and driving comfort. In scope of this topic, the presented work introduces results of experimental investigations on a pure electric ABS installed on an electric powered sport utility vehicle (SUV) test platform with individual switch reluctance on-board electric motors transferring torque to the each wheel through the single-speed gearbox and half-shaft. The study presents test results of the vehicle braking on inhomogeneous low-friction surface for the case of ABS operation with front electric motors.
Journal Article

Influence of Active Camber Control on Steering Feel

Research of the past century has demonstrated that wheel camber regulation provides great potential to improve vehicle safety and performance. This led to the development of various prototypes of the camber mechanisms over the last decade. An overview of the existing prototypes is discussed in the presented paper. Most of the investigations related to camber control cover open-loop maneuvers to evaluate a vehicle response. However, a driver’s perception and his reaction can be the most critical factor during vehicle operation. Therefore, the research goal of the presented study is to assess an influence of active camber control on steering feel and driving performance using a driving simulator. In the proposed investigation, a dSPACE ASM vehicle model has been extended by introducing advanced models of steering system and active camber regulation. The steering system describes dynamics of steering components (upper and lower columns, torsion bar, steering rack and others).
Journal Article

Design and Testing of ABS for Electric Vehicles with Individually Controlled On-Board Motor Drives

The paper introduces the results of the development of anti-lock brake system (ABS) for full electric vehicle with individually controlled near-wheel motors. The braking functions in the target vehicle are realized with electro-hydraulic decoupled friction brake system and electric motors operating in a braking mode. The proposed ABS controller is based on the direct slip and velocity control and includes several main blocks for computing of predictive (feedforward) and reactive (feedback) brake torque, wheel slip observer, slip target adaptation, and the algorithm of brake blending between friction brakes and electric motors. The functionality of developed ABS has been investigated on the HIL test rig for straight-line braking manoeuvres on different surfaces with variation of initial velocity. The obtained experimental results have been compared with the operation of baseline algorithm of a hydraulic ABS and have demonstrated a marked effect in braking performance.
Technical Paper

Investigation of Brake Control Using Test Rig-in-the-Loop Technique

Research and development tools for investigations of various facets of braking processes cover three major groups of devices: Dynamometer test rigs: assessment of performance, durability, life cycle and others; Tribometer test rigs: definition of parameters of friction and wear; Hardware-in-the-loop: estimation of functional properties of controlled braking. A combination of the listed devices allows to research complex phenomena related to braking systems. The presented work discusses a novel approach of test rig fusion, namely the combination of a brake dynamometer and hardware in the loop test rig. First investigations have been done during the operation of the anti-lock braking system (ABS) system to demonstrate the functionality of the approach.
Journal Article

Influence of the Tire Inflation Pressure Variation on Braking Efficiency and Driving Comfort of Full Electric Vehicle with Continuous Anti-Lock Braking System

The presented study demonstrates results of experimental investigations of the anti-lock braking system (ABS) performance under variation of tire inflation pressure. This research is motivated by the fact that the changes in tire inflation pressure during the vehicle operation can distinctly affect peak value of friction coefficient, stiffness and other tire characteristics, which are influencing on the ABS performance. In particular, alteration of tire parameters can cause distortion of the ABS functions resulting in increase of the braking distance. The study is based on experimental tests performed for continuous ABS control algorithm, which was implemented to the full electric vehicle with four individual on-board electric motors. All straight-line braking tests are performed on the low-friction surface where wheels are more tended to lock.
Technical Paper

Combined Testing Technique: Development of Friction Brake System for Electric Vehicle

The presented research discusses the experimental procedure developed for testing of friction brake systems installed on the modern electric vehicles. Approach of combined experimental technique utilizing hardware-in-the-loop platform and brake dynamometer is introduced. As the case study, an influence of brake lining coefficient of friction fluctuations on the anti-lock brake system (ABS) performance is investigated. The ABS algorithm is represented by the direct slip control aimed to the precise tracking of reference slip ratio by means of electric and friction brake system. Vehicle prototype is represented by RWD electric vehicle with in-wheel motors. Results, representing the investigated phenomenon, are derived using the developed combined test bench. The achieved results give a basis for further extension of standard brake testing procedures.
Technical Paper

Influence of Active Subsystems on Electric Vehicle Behavior and Energy Characteristics

Nowadays there is a tendency to implement various active vehicle subsystems in a modern vehicle to improve its stability of motion, handling, comfort and other operation characteristics. Since each vehicle subsystem has own limits to generate supporting demand, their potential impact on vehicle dynamics should be analyzed for steady-state and transient vehicle behavior. Moreover, the additional research issue is the assessment of total energy consumption and energy losses, because a stand-alone operation of each vehicle subsystem will provide different impact on vehicle dynamics and they have own energy demands. The vehicle configuration includes (i) friction brake system, (ii) individual-wheel drive electric motors, (iii) wheel steer actuators, (iv) camber angle actuators, (v) dynamic tire pressure system and (vi) actuators generating additional normal forces through external spring, damping and stabilizer forces. A passenger car is investigated using commercial software.
Journal Article

Estimation of Brake Friction Coefficient for Blending Function of Base Braking Control

The brake architecture of hybrid and full electric vehicle includes the distinctive function of brake blending. Known approaches draw upon the maximum energy recuperation strategy and neglect the operation mode of friction brakes. Within this framework, an efficient control of the blending functions is demanded to compensate external disturbances induced by unpredictable variations of the pad disc friction coefficient. In addition, the control demand distribution between the conventional frictional brake system and the electric motors can incur failures that compromise the frictional braking performance and safety. However, deviation of friction coefficient value given in controller from actual one can induce undesirable deterioration of brake control functions.
Journal Article

Coordination of Steer Angles, Tyre Inflation Pressure, Brake and Drive Torques for Vehicle Dynamics Control

During vehicle operation, the control objectives of stability, handling, energy consumption and comfort have different priorities, which are determined by road conditions and driver behavior. To achieve better operation characteristics of vehicle, coordinated control of vehicle subsystems is actively used. The fact of more active vehicle subsystems in a modern passenger car provides more flexibility for vehicle control and control algorithm development. Since the modern vehicle can be considered as over-actuated system, control allocation is an effective control technique to solve such kind of problem. This paper describes coordination of frictional brake system, individual-wheel drive electric motors, active front and rear steering, active camber mechanisms and tyre pressure control system. To coordinate vehicle subsystems, optimization-based control allocation with dynamic weights is applied.