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Technical Paper

Designing a Next Generation Trailer Braking System

Passenger vehicles have made astounding technological leaps in recent years. Unfortunately, little of that progress has trickled down to other segments of the transportation industry leaving opportunities for massive gains in safety and performance. In particular, the electric drum brakes on most consumer trailers differ little from those on trailers over 70 years ago. Careful examination of current production passenger vehicle hardware and trailering provided the opportunity to produce a design and test vehicle for a plausible, practical, and performant trailer braking system for the future. This study equips the trailer with high control frequency antilock braking and dynamic torque distribution through use of passenger vehicle grade apply hardware.
Technical Paper

Modeling Rack Force for Steering Maneuvers in a Stationary Vehicle

A steering system converts circular motion of the steering wheel into yaw motion of the road-wheels. In absence of a steering assist mechanism, the driver torque overcomes the tire-road friction forces, which is transmitted to the steering rack through tie rods attached to the road-wheels. The net force acting on the rack is then transmitted to the steering wheel through mechanical linkages which results in a natural haptic feedback, commonly referred to as the steering feel. In an electric/hydraulic power steering, an electro-mechanical actuator applies assist force, which reduces the torque required by the driver. In order to maintain stability of the power steering system while generating a desired steering feel, it is therefore crucial to accurately model steering rack force. We present a model for the rack force, which is generated while performing steering maneuvers in a stationary vehicle.
Technical Paper

Nonlinear Hydraulic Antilock Braking System and Fuzzy Control with Variable Slip Frequency Control to Improve Stopping Distance in Heterogeneous Road

A lot of the antilock braking system (ABS) models were studied and proposed by the researcher, and were often in the quarter-car model half car model and full car model. The models could be ABS with hydraulics, pneumatic, or eddy current electro magnetic energy transmission for braking processes. Many types of ABS controller method were also studied and developed to achieve the best control response, such as stopping time and distance even steering ability effects of nonlinear braking dynamics and the heterogeneous of road surface-wheel interaction. There are non-intelligent such as Proportional integral derivative (PID), Observer, sliding mode, LQR and artificial intelligence controls such as fuzzy, and neural network (NN) and even a hybrid of both, controllers are commonly applied to control the developed ABS design.
Technical Paper

Virtual ECU Development for Antilock Braking System (ABS)

Nowadays there is an increasing dependency on electronic content in the automobile sector for safety purposes and performance requirements. This is the reason for Anti-Lock Braking System (ABS) being an active feature for the vehicles. ABS is used to stop the vehicle without wheel locking. Conventional techniques used to design and manufacture the Anti-lock Brake System, are based on real-time analysis and design. These techniques are time consuming and are always not compatible with other kinds of vehicles. This paper presents a new method of design and prototype realization of the ABS. This is based on the virtual environment, which gives a generic solution to all kinds of vehicles in real design and manufacturing. Virtualization allows simulation of automotive ECUs on a Windows PC executed in a closed-loop with vehicle simulation model.
Technical Paper

Variability Analysis of FMVSS-121 Air Brake Systems: 60-mi/hr Service Brake System Performance Data for Truck Tractors

In support of the Federal Motor Carrier Safety Administration’s (FMCSA’s) ongoing interest in connected and automated commercial vehicles, this report summarizes analyses conducted to quantify variability in stopping distance tests conducted on commercial truck tractors. The data used were retrieved from tests performed under the controlled conditions specified for FMVSS-121 air brake system compliance testing. The report explores factors affecting the variability of the service brake stopping distance as defined by 49 CFR 571.121, S5.3.1 Stopping Distance—trucks and buses stopping distance. Variables examined in this analysis include brake type, weight, wheelbase, and tractor antilock braking system (ABS). This analysis uses existing test data collected between 2010 and 2019. Several of the examined parameters affected both tractor stopping distance and stopping distance variability.
Technical Paper

Comparative Analysis of Methods to Estimate the Tire/Road Friction Coefficient Applied to Traffic Accident Reconstruction

This study presents a comparison of three methods: VC4000PC accelerometer, Sensor Kinetics mobile app, and video analysis by Tracker (free software). The methods have been compared experimentally for emergency braking with locked wheels, as well as using the antilock braking system (ABS). Data from the three methods were recorded simultaneously. Data analysis was made, applying inferential statistics. The results from the analysis of variance (ANOVA) and precision analysis indicate that data collected with the smartphone app ensures good accuracy and does not provide significant differences in comparison with the accelerometer, while the video analysis method showed some statistical differences. The regression analysis yielded an estimation coefficient R2 close to 1, and a residual standard error (RSE) being almost 0, for all experiments, parameters that indicated a good linear regression for both low-cost methods as a function of the accelerometer.
Technical Paper

An Investigation into the Traction and Anti-Lock Braking System Control Design

Wheel slip control is crucial to active safety control systems such as Traction Control System (TCS) and Anti-lock Braking System (ABS) that ensure vehicle safety by maintaining the wheel slip in a stable region. For this reason, a wide variety of control methods has been implemented by both researchers and in the industry. Moreover, the use of new electro-hydraulic or electro-mechanical brakes, and in-wheel electric motors allow for a more precise wheel slip control, which should further improve the vehicle dynamics and safety. In this paper, we compare two methods for wheel slip control: a loop-shaping Youla parametrization method, and a sliding mode control method. Each controller is designed based on a simple single wheel system. The benefits and drawbacks of both methods are addressed. Finally, the performance and stability robustness of each controller is evaluated based on several metrics in a simulation using a high-fidelity vehicle model with several driving scenarios.
Journal Article

Integrated Regenerative Braking System and Anti-Lock Braking System for Hybrid Electric Vehicles & Battery Electric Vehicles

This paper describes development of an integrated regenerative braking system and anti-lock brake system (ABS) control during an ABS event for hybrid and electric vehicles with drivelines containing a single electric motor connected to the axle shaft through an open differential. The control objectives are to recuperate the maximum amount of kinetic energy during an ABS event, and to provide no degraded anti-lock control behavior as seen in vehicles with regenerative braking disabled. The paper first presents a detailed control system analysis to reveal the inherent property of non-zero regenerative braking torque control during ABS event and explain the reason why regenerative braking torque can increase the wheel slip during ABS event with existing regenerative braking control strategies.
Technical Paper

Vehicle Control History: Data from Driver Input and Pre-Collision System Activation Events on Toyota Vehicles

Separate from the event data recorder (EDR), which records and stores data from qualifying vehicle crash events, the Vehicle Control History (VCH) on Toyota vehicles records and stores certain vehicle data based on select driver inputs, such as hard acceleration or braking, or upon the activation of certain vehicle dynamic control systems such as antilock braking system (ABS), traction control (TRAC), vehicle stability control (VSC), and the pre-collision system (PCS). In the United States, VCH was first equipped on the 2013 Toyota RAV4 and has been subsequently introduced into other Toyota and Lexus models. Most recently, in addition to VCH data, additional PCS operational data (PCS-O) and image data (PCS-I) may be recorded and stored. The image storage capability may record under certain conditions such as if the system has automatically applied the vehicle brakes.
Journal Article

Combi Brake System (CBS) Design and Tuning on an Electric Two Wheeler for Cornering Maneuver

To reduce the number of traffic accidents, most of the governments have mandated to include Combi Brake System (CBS) or Anti-lock Braking System (ABS) in two wheelers. While most of the homologation requirements for CBS can be fulfilled by straight line motion, CBS behavior is crucial while cornering for safety aspects. When vehicle is in cornering motion, the lateral forces generated at the tire decreases the effective longitudinal force available, which implies lesser braking force at tire. This paper represents a design methodology for tuning CBS for various critical scenarios mainly during cornering maneuver. A detailed study has been made at various combination of vehicle lean angle, vehicle speed and friction coefficient of road (μ) in straight line and cornering maneuver to effectively decide on front to rear brake force distribution to avoid either of the tires’ lock-up.
Technical Paper

Braking Requirements for Optimizing Autonomous Emergency Braking Performance

Vehicle technology new developments have contributed to improve vehicle structural performance and therefore passive protection, but also the inclusion of electronic control units has provided new opportunities to expand active safety systems. This is the case for systems like anti-lock braking systems (ABS), electronic stability control (ESC) and brake assist (BA) among others. A more advanced generation of active systems includes sensorial units that monitor vehicle’s surrounding and detect potential hazards, such as an imminent collision, and performs an automatically and commanded emergency braking to lessen or mitigate the consequences of the impending accident. For this latest system, the so-called autonomous emergency braking (AEB), various consumer testing protocols, such as Euro NCAP protocols [1], propose and periodically update test catalogues in order to evaluate the performance of such systems and later to inform potential consumers.
Technical Paper

Pressure Optimization Control of Electro-Mechanical Brake System in the Process of ABS Working

The electro-mechanical brake booster (EMBB) and hydraulic control unit (HCU) constitute the electro-mechanical brake system, which can meet the requirements of brake system for intelligent vehicles. It does not need vacuum source, provides active braking function, have high control accuracy and fast response. But it has two electronic control units (ECU), which need coordinated control. When ABS is triggered, the pressure of the master cylinder keeps rising and falling, and the pressure fluctuates greatly. This will lead to noise and reduce the durability of the system. In this paper, a pressure optimization control strategy under ABS condition is proposed. Firstly, the structure and control strategy of EMBB are introduced. Secondly, the braking characteristics without pressure optimization control are analyzed. Thirdly, based on the demand of maximum cylinder pressure, a three-closed-loop pressure optimization control strategy is established.
Journal Article

Reconstructing Vehicle Dynamics from On-Board Event Data

Modern vehicles record dynamic data from a number of on-board sensors for events that could precede a crash. These data can be used to reconstruct the behavior of a vehicle, although the accuracy of these reconstructions has not yet been quantified. Here, we evaluated various methods of reconstructing the vehicle kinematics of a 2017 and a 2018 Toyota Corolla based on Vehicle Control History (VCH) data from overlapping events generated by the pre-collision system (PCS), sudden braking (SB) and anti-lock brake (ABS) activation. The vehicles were driven towards a stationary target at 32-64 km/h (20-40 mph) and then after the pre-collision alarm sounded the vehicle was steered sharply right or left and braked rapidly to rest. VCH data for PCS event were recorded at 2 Hz and for the sudden braking and ABS activation events at 6.7 Hz.
Technical Paper

Performance and Comfort Optimization from ABS/CBS/Motor Regenerative Braking in an Electric Two Wheeler during Heavy and Mild Braking Respectively

Reducing the number of traffic accidents is a declared target of most governments leading to mandating Combined Braking System (CBS) or Anti-lock Braking System (ABS) in two wheelers. Traditional friction braking torque and motor braking torque can be used in braking for electric 2wheeler. Use of CBS and ABS helps in active control of vehicle braking leading to better deceleration, prevention of tire locking, control on vehicle pitch etc. A braking model (friction braking + motor regenerative braking) along with battery dynamics is developed in Matlab/Simulink and validated with real vehicle response. This paper presents an analysis on vehicle braking separately for heavy and mild braking in various vehicle load conditions. During heavy braking a feedback control algorithm is used to maintain optimal slip ratio both at the front and rear tire, active control on CBS and ABS+Regen is done and performance is compared.
Technical Paper

ABS Optimization for a Two-Wheeler Based on Tire-Road Friction Characteristics

Anti-lock Braking System (ABS) is a well-known active safety technology widely used in cars. Recently, it has become a mandatory safety feature for two-wheelers. In principle, ABS ensures an optimum braking performance by not allowing the tire to slip beyond a certain level. This guarantees steering stability and peak braking performance of the tire during panic braking situations. As the ABS controller depends on the tire characteristics information for its algorithm, a change in tire or pavement can vary the optimum operating range of ABS. In addition to this, motorcycle tires differ from a car tire in terms of its construction, dimension and compound. Therefore, the motorcycle tire’s performance envelope cannot be directly compared to a car tire. This work presents a methodology which aims to acquire the tire-road friction characteristics of three different tires for a study motorcycle on different friction surfaces through experimentation and estimation techniques.
Technical Paper

Open-Loop Characteristics Analysis and Control of High Speed On-Off Valve

In the process of ABS control, the Anti-lock braking system (ABS) of the vehicle adjusts the wheel cylinder brake pressure through the hydraulic actuator so as to control the movement of the wheel. The high-speed on-off valve (HSV) is the key components of the Anti-lock braking system. HSV affects the performance of the hydraulic actuator and the valve response characteristics affects the Anti-lock braking system pressure response as well as braking effect. In this paper, the electromagnetic field theory and flow field theory of HSV are analyzed, and simulation analysis of electromagnetic field characteristics of HSV is done by ANSYS. Combined with the ANSYS analysis results, a precise physical model of HSV is constructed in AMESim. Meanwhile, the valve response characteristics are analyzed. Moreover, the influence of different wheel cylinder diameter and PWM carrier frequency on hydraulic braking force characteristics are analyzed.
Technical Paper

Sizing of anti-lock braking system for Formula SAE vehicles

The anti-lock braking system (ABS) has the purpose of controlling the wheel slip, in order to maintain steering and stability during braking. Due to the increasing search for safety and performance in competition vehicles, it is sought to minimize braking distances for the purpose of reduce track time. It is known that a slip control task is not trivial, where one of the main reasons is the high amount of uncertainties involved. Thus, the present paper aims to simulate a SAE vehicle with and without ABS using reliable experimental data of friction interfaces. The performance of the system is evaluated by a longitudinal vehicle model, supported by principles of vehicular dynamics, dynamometric test and track data. The model has a feedback control system with two proportional, integral, derivative (PID) loops. A sensor monitors wheel slip and feed it to the controller.
Technical Paper

ABS Control Algorithm Based on Direct Slip Rate for Hybrid Brake System

The brake-by-wire system (BBW) is better match the new energy vehicle in the future direction of development. The electro-mechanical brake (EMB) is lack of the brake failure backup and need a high 42 V voltage for the power supply. This paper presents a new brake-by-wire hybrid brake system (HBS) with the electro-hydraulic brake (EHB) equipped on the front wheels and the EMB equipped on the rear wheels. The combination of these two brake-by-wire systems has advantages of both the EHB and EMB system. The EMB on the rear wheels totally removing the rear pipes and can be simply mounted. In addition, since the need of brake torque on the rear axle is relatively small, the power supply of EMB can be reduced to 12 V. Meanwhile, the EHB on the front wheels has the failure backup function through the hydraulic line. The HBS can quickly and accurately regulate four wheels brake force of vehicles which can well meet the requirement of antilock brake system (ABS).
Technical Paper

Travelling Resistance Estimation and Sandy Road Identification for SUVs

The mechanical properties of sandy road are quite different from those of hard surface road. For vehicle control systems such as EMS (engine management system), TCU (transmission control unit) and ABS (antilock brake system), the strategies and parameters set for solid surface road are not optimal for driving on sandy road. It is an effective way to improve the mobility of all-terrain vehicles by identifying sandy road online and shifting the control strategies and parameters of control systems to sandy sets. In this paper, a sandy road identification algorithm for SUVs is proposed. Firstly, the vehicle signals, such as engine torque and speed, gear position, wheel and vehicle speed, are acquired from EMS, TCU and ESP (electronic stability program) through CAN (controller area network) bus respectively. Based on the information and longitudinal force equilibrium equation, the travelling resistance of vehicle is estimated.
Journal Article

Design of Anti-lock Braking System Based on Regenerative Braking for Distributed Drive Electric Vehicle

In this article, the regenerative braking system is designed, which can realize the torque allocation between electric braking and hydraulic braking, where the cost function designed in this article considers factors of braking torque following effect, energy regenerative power, and hydraulic braking consumed power. In addition, a complete anti-lock braking system (ABS) is designed, which is based on regenerative braking. With the optimal slip ratio as control target, target wheel speed, control wheel speed, braking torque control strategy, and enable/disenable control logic of ABS are determined. By MATLAB/Simulink-DYNA4 co-simulation and real vehicle test, the feasibility and applicability of ABS based on regenerative braking are verified, under the condition of small severity of braking.