Dry Asphalt Road Research Articles

Analysis of the Braking System in the Gardapati Prototype Energy Saving Car

The braking system is one of the crucial components in a vehicle because braking is a vital safety feature of the vehicle. The braking system functions to reduce or slow down the speed and stop the vehicle, as well as to enable the possibility of parking the vehicle on a downward slope. The braking system under investigation is examined in the prototype vehicle called Gardapati, which employs a hydraulic brake system. Gardapati is a vehicle created by students from the University of Riau's Mechanical Engineering Department, affiliated with the UKM Selembayung, following the standard references provided by the Energy-Efficient Vehicle Competition organized by BPTI.
 This final project will involve several calculations related to the braking system, following the specifications used in the Gardapati vehicle. First, calculations will determine the dynamic braking force required (Fb) when the vehicle is moving at a speed of 50 km/h with a distance of 20 meters, as well as the static braking force (Fb) required when the vehicle is on an incline of 11.2 degrees, adjusted to the requirements and regulations of the 2023 Energy-Efficient Vehicle Competition (KMHE). Then, the braking distance will be calculated for speeds of 30, 40, and 50 km/h on dry and wet asphalt road conditions.
 From the calculation results and data analysis, it is found that the required dynamic braking force (Fb) is 510,76 N, and the static braking force (Fb) is 830,31 N. Meanwhile, the minimum braking distance is observed on dry asphalt road conditions at a speed of 30 km/h with a percentage error of 1,59 %, where the theoretical value is 5.67 m and the actual value is 5,76 m. On the other hand, the highest braking distance is observed on wet asphalt road conditions at a speed of 50 km/h with a percentage error of 7,39%, where the theoretical value is 14.47 m and the actual value is 15.54 m. Of the two road conditions, the largest percentage error occurs when testing the vehicle at speeds of 30, 40, and 50 km/h on wet asphalt conditions, amounting to 4,61%. With this level of percentage error, it can be concluded that the variation in the obtained data is relatively small, which is less than 10%.

On-site road properties evaluation for dry and wet asphalt roads using an imaging luminance measurement device

A method was developed to investigate the reflected properties of LED and HPS-lighted wet roads using on-site measurement of luminance images. An ILMD was used to obtain high observation angles by placing it at a close distance to the ROI. The luminance images were analyzed to derive a distribution of reflected luminance as a function of deviation, incidence, and observation angles. Furthermore, an investigation of the reflected characteristics of a dry asphalt road illuminated by LED lighting was conducted, employing on-site measurements of the images of luminance and the distribution of illuminance. The results provide valuable insights for designing lighting systems and mitigating the adverse effects of glare and specular reflection on road safety.

Comparison of braking properties of selected vehicle with different methods

The aim of this article was to perform a practical measurement of the braking properties of a selected Škoda Yeti vehicle on a wet and dry asphalt road and then evaluate and compare the measured data using a decelerograph and a mobile application mSTK. It is a new application for measuring driving dynamics, which was developed for the needs of technical inspection stations in Slovakia. The subject was the intensive braking of a Škoda Yeti passenger car with a fully compressed service brake from different velocities and on different surfaces. A total of 18 measurements were performed, of which 9 on the dry and 9 on the wet surface. This is a new alternative method for recording vehicle driving dynamics. The developed application in conjunction with modern smartphones can thus compete with the current decelographer, both in terms of technical parameters, measurement accuracy (total average deviation 2.11%) and ease of use. The results and data processed in this way are presented in the final part of the paper.

Road Surface State Recognition Based on Semantic Segmentation

In extreme bad weather conditions, vehicles can timely adjust the speed and distance according to the road information, which will effectively reduce the occurrence of traffic accidents. Road type and road adhesion coefficient are the main factors affecting road condition. The traditional identification method of road adhesion coefficient has the characteristics of high cost and low reliability. At the same time, the road surface information recognition technology based on machine vision has become a hot spot in the current research, but the low accuracy and poor robustness are always the difficulties in the research. Based on the semantic segmentation model which is popular in machine vision, a new pavement type recognition technology is proposed by improving the model output network. According to the existing literature, vehicle road surface can be divided into the following 9 categories, including wet asphalt road, dry asphalt road, wet concrete road, dry concrete road, wet soil road, dry soil road, gravel road, compacting snow road and icy road. The standard data set is made by collecting road pictures through taking photos, downloading and other ways, and the pre-processed data set is used to train the improved semantic segmentation network model. Through many tests, training parameters that achieve the desired effect are selected for model parameter solidification, and the semantic segmentation model after solidification is used to predict the road image acquired by the camera. According to the prediction results of the model, the categories of the current driving road surface are obtained. The test results of a large number of road images show that the average classification accuracy of the nine road types is about 94%, which effectively improves the identification accuracy and robustness of the current road types. At the same time, the predicted time of a single frame image on a specific test platform is about 0.028 6 s, which meets the real-time requirements.

4륜 독립 구동 전기 자동차의 제동력 분배 방법에 대한 연구

This paper describes a new electronic brake distribution(EBD) method for electric vehicles with a four-wheel independent-drive motor. The proposed EBD logic consists of an FF(Feedforward) control part based on the vertical force ratio of each wheel for the braking stability of a vehicle, and an FB(Feedback) control part to secure robustness against load weight changes. In addition, a new brake force distribution logic toward regenerative braking and hydraulic friction braking was proposed, which was designed to allow easy transition between the maximum recuperation strategy and the braking stability maximization strategy. Simulation tests were conducted to investigate the feasibility and performance of the proposed control on a dry asphalt road. The results show that the EBD logic effectively maintains braking stability and robustness against load changes.

Sensitivity analysis of tyre characteristic parameters on ABS performance

This study aims to provide quantitative insight into the sensitivity of tyre parameters on the performance of the anti-lock braking system (ABS) control algorithms. Unlike conventional sensitivity analysis methods, which depend on a few test cases, in this study, Magic Formula (MF) 6.1 tyre model is used to generate a comprehensive set of thousands of virtual tyres that encompasses all possible combinations of the four main longitudinal parameters. To broaden the scope of impact of this study, two ABS controllers – one based on wheel spin acceleration (literature version of Bosch ABS) and the other based on sliding mode control (SMC) are designed in MATALB-Simulink and integrated with IPG Carmaker to perform complete vehicle dynamics simulations. Straight-line ABS simulations are performed on dry asphalt road using both the controllers and each test-run is performed for five different set-point longitudinal slip ratios (). The results of the conditional variance-based sensitivity analysis consisting of 211,250 simulation tests indicate that the tyre peak friction coefficient and shape factor have significant contributions to ABS stopping distance. The sensitivity for stopping distance to tyre parameters varies amongst the controllers. While with Bosch algorithm parameter D almost completely controls the stopping distance, the sliding mode ABS is sensitive to parameters , C and D. Tyre parameter interactions indicated by the factor , though hard to visually interpret, is expounded using global sensitivity analysis metrics.

Coordinated collision avoidance for connected vehicles using relative kinetic energy density

Vehicular collision often leads to serious casualties and traffic congestion, and the consequences are worse for multiple-vehicle collision. Many previous works on collision avoidance have only focused on the case for two consecutive vehicles using on-board sensors, which ignored the influence on upstream traffic flow. This paper proposes a novel coordinated collision avoidance (CCA) strategy for connected vehicles, which has potential to avoid collision and smooth the braking behaviors of multiple vehicles, leading to an improvement of traffic smoothness. Specifically, model predictive control (MPC) framework is used to formulate the CCA into an optimization problem, where the objective is to minimize the total relative kinetic energy density (RKED) among connected vehicles. Monte Carlo simulations are used to demonstrate the effectiveness of proposed CCA strategy by comparison with other two strategies. Among all the three control strategies, the RKED based control strategy shows the best performance of collision avoidance, including the best crash prevention rates (99.2 % on dry asphalt road and 90.5 % on wet asphalt road) and the best control of distance headways between vehicles.

Study of the traffic noise source intensity emission model and the frequency characteristics for a wet asphalt road

The traffic noise source intensity emission model is the basis of traffic noise prediction. In addition, the presence of water on the road is an important factor of road traffic noise. However, to date, none of the traffic noise source intensity emission models account for a situation in which the road surface is wet. Therefore, the main objective of this paper is to build a traffic noise source intensity emission model on a wet asphalt road based on traffic noise measurements, in which speed, sound pressure level and frequency spectrum were recorded as a single vehicle passed by. By using statistical analysis on the measurement data, a traffic noise source intensity emission model on a wet asphalt road was acquired, which conforms to correlation test, F-test and t-test. The result shows that the sound pressure level increases considerably with the presence of water on asphalt road for all types of vehicles; the mean difference in the sound pressure level between the wet and dry asphalt roads for light, middle-size, and heavy vehicles are 10.09dB(A), 5.56dB(A), and 4.26dB(A), respectively. In addition, the noise difference between a wet and dry asphalt road decreases as the speed and vehicle size grow. Furthermore, the frequency characteristics of the road traffic noise were analysed through the sound pressure level and noise energy percentage in the 1/3 octave band spectrum. The result shows that for the wet asphalt road, the sound pressure level is high at high frequency and low at low frequency, which is completely different from the response on a dry asphalt road. In addition, for a dry asphalt road, the vehicle’s noise energy percentage at low frequency decreases as the speed increases, whereas at high frequency, the percentage increases as the speed grow. However, for a wet asphalt road, the noise energy percentage changes little with speed. The findings can be applied to the accurate traffic noise prediction and noise control, especially in the rainy regions.

Designing a set of efficient regenerative braking strategies with a performance index tool

The goal of this study is to design efficient regenerative braking strategies for a recreational three-wheel rear-wheel-drive hybrid electric vehicle. Current studies provide several optimal regenerative braking strategies, but no tool to obtain a set of acceptable strategies. A performance index tool is thus proposed and used to evaluate the efficiency of a given strategy. With this tool it is then possible to define a set of efficient regenerative strategies. The performance index is based on knowledge of a global efficiency map defined as the ratio of the incoming battery power to the extracted kinetic power. Two simulators of the vehicle are implemented in MATLAB/Simulink: one with a rear-wheel slip model and the other without slip considerations. They also include the longitudinal dynamics of the vehicle and the efficiency of the electrical drive from the electric motor to the battery. They were validated with experimental measurements of several accelerations and decelerations on a dry asphalt road from 0 km/h to 60 km/h. The simulated global efficiency map was also experimentally validated by regenerative braking measurements on a dry asphalt road from 50 km/h to 0 km/h. The simulated global efficiency map is used to design the optimal strategy (with and without wheel slip considerations). The performance map deduced from the global efficiency map was used to define the boundaries for the optimal strategy deviations and hence to limit the regenerated energy drop. Simulations show that there is a wide range of acceptable strategies from 0 km/h to 50 km/h on a dry asphalt road and hence give the driver the possibility of modulating the regenerative braking within a good energy recapture level. Finally, the design methodology presented with a simulated global efficiency map is also applicable with an experimental efficiency map which can be updated online.

Comparison of Summer and Winter Tyres on a Dry and Snowy Surface

Abstract The paper describes the comparison of braking properties of summer and winter tyres on a vehicle Škoda Octavia II, 2.0 TDI (103 kW), with summer tyres Michelin Pilot Primacy 225/45 R17 91W and winter tyres Dunlop SP Winter Sport 3D 195/65 R15 91T. Testing was done in summer on a dry asphalt road and in winter on a snowy asphalt road with compacted snow without gritting. A device for the measuring of deceleration was XL Meter Pro Alpha.

Direct adaptive neural control of antilock braking systems incorporated with passive suspension dynamics

A direct adaptive neural network-based feedback linearization (NNFBL) slip control scheme for an antilock braking system (ABS) is presented. The NNFBL slip controller is developed to minimise the vehicle braking distance and to simultaneously improve its overall ride comfort and road handling. The comprehensive vehicle model incorporates the passive suspension dynamics, the dynamics of the electro-mechanical based braking system and air drag and wheel bearing friction. A feedforward, multilayer perceptron (MLP) neural network (NN) model that is well suited for control by discrete input-output linearization (NNIOL) is selected to represent the ABS with passive suspension. The NN model was trained using Levenberg-Marquardt optimization algorithm. The controlled signal was further boosted using a genetic algorithm generated gain. The effectiveness of the proposed controller is demonstrated by simulation results, in the presence of deterministic road disturbance input to the suspension and varying road conditions. The results are superior with respect to braking distance minimization and also to reference slip tracking, especially on the dry asphalt road.

Study of the Antilock Braking System with Electric Brake Force Distribution

Antilock braking system (ABS) is a standard equipment for passenger car, it can prevent automobile wheels from locking-up and improve braking performance. Electronic brake force distribution (EBD) can prevent the rear wheels from locking prior to the front wheels, it can automatically adjust the braking force distribution scale among the wheels. In this paper, a vehicle model and tire model are developed, a sliding mode controller is designed for ABS system and a fuzzy controller is designed for EBD system. Dry asphalt road and wet asphalt road are used to simulate the performance of ABS/EBD system. The simulation results show that the control method can make full use of the respective advantages of ABS and EBD systems.

Model-based detection of critical driving situations with fuzzy logic decision making

A precise knowledge about the current driving condition is getting increasingly important for future driver assistance systems like global chassis control or collision avoidance systems for avoiding any critical driving situation. Moreover a precise knowledge about the driving situation can be used in testing, in evaluation, and for comparison of new passenger cars. A two degree of freedom model of vehicle lateral dynamics is used to derive a characteristic velocity stability indicator (CVSI). The CVSI is used to distinguish between different driving and stability conditions (i.e. understeering, oversteering, and neutralsteering). This forms the basis for a driving condition detection system with fixed thresholds. It is then extended to a detection system with fuzzy logic thresholds. The CVSI and the fuzzy systems are compared experimentally using (i) a slalom test drive on an icy road and (ii) a stationary circular test drive on a dry asphalt road.

Increase of Frictional Force of Rubber Block by Uniform Contact Pressure Distribution and its Application to Tire

Abstract The theorem on the relationship between pressure distribution and the frictional force was derived: “The frictional force is maximized when the pressure distribution is uniform, if μ(P)P is convex with respect to P where μ(P) and P are friction coefficient and pressure.” In order to verify this theorem, the surface shape of the rubber block with the uniform pressure distribution was designed by the optimization technique. The surface shape of the optimized block was dependent on the friction coefficient of contact surface. The optimized block for dry surface increased the frictional force two to ten percent on dry steel and the optimized block for ice surface increased eight percent on ice. The technology of optimized block for dry surface was applied to a tire and verified to be effective for traction on dry asphalt road, maneuverability, comfort and wear.