Braking Deceleration Research Articles

Does the Final Score Influence the Physical Demands of Women’s Handball Matches?

The purpose of this study was twofold: to analyze and compare the influence of the final score of the match (close, balanced and unbalanced) on physical demands during official competitions in women’s handball; and to investigate if the physical demands of each playing position are affected by the final score. Twenty-two semi-professional female players from the Spanish 2nd Division were monitored across 13 official matches. Total distance (TD), high-speed running (HSR), high-intensity braking distance (HIBD), accelerations (ACC), decelerations (DEC) and PlayerLoad (PL) were collected in absolute and relative values using a local positioning system (WIMU PRO™, Realtrack Systems S.L., Almería, Spain). Two-way ANOVA with partial Eta-squared and Cohen’s d were used to determine the differences between playing positions and match types. Unbalanced (16.4±4.1 n·min−1) and balanced matches (15.2±3.8 n·min−1) elicited higher DEC/min than close matches (13.1±2.8 n·min−1) (p<0.001, moderate effects). In relation to playing positions, wings covered the largest TD and registered the highest values of PL in balanced and unbalanced matches (p<0.001, large effects). Also, wings presented the highest values of HIBD, HSR and HSR/min regardless of the final score (p<0.05, moderate effects). Moreover, wings performed largely more number of ACC and DEC compared to pivots in unbalanced matches (p<0.05, large effects). In conclusion, this study showed that the final score of the match influences the physical demands experienced by female handball players during official competitions. This information should be considered by coaches to adapt and periodize the training load across the microcycle.

Analysis of Longitudinal Braking Stability of Lightweight Liquid Storage Mini-Track Vehicles

In this study, a theoretical model was established for longitudinal braking stability (LBS) of a lightweight liquid storage mini-track vehicle to investigate its behaviors. The influence of the tank liquid filling ratio (TLR), initial velocity (IV), and initial braking deceleration (IBD) on the LBS of the tracked vehicle was studied via FLUENT simulation. The simulation results showed that when the IV and the IBD were constant, the TLR significantly affected the braking efficiency. Conversely, when the TLR was 0.7, the braking efficiency decreased by 32%, resulting in the worst LBS. The braking efficiency at different IVs decreased by ~30% when using a constant IBD and TLR, and the braking stability exhibited little difference. Further, the braking efficiency decreased noticeably with increasing IBD; meanwhile, the braking longitudinal stability worsened. When the IBD was increased to 5 m⋅s−2, the braking efficiency decreased by 48.4%. The road experiment showed that when the tracked vehicle was accelerated and braked under limit conditions, the stability requirements were met. Finally, by combining the simulation and road experiment, the driving parameters of the tracked vehicle that could satisfy the LBS were obtained.

Development of Driving Robot and Driver Model Applied Regenerative Brake Control of Electrified Vehicles

Real driving emissions (RDE) test procedures for type approval were initiated in Japan in 2022. In Japan, the test vehicle is driven on a test road (test course) by tracing the speed pattern prepared for each RDE test. The vehicle needs to trace the patterns in the same manner as in the conventional chassis dynamometer test. The use of a driving robot is effective for reproducibility in precisely tracing the target vehicle speed during these tests. In this study, we developed a driving robot for electrified vehicles (HEV, plug-in HEV, BEV, and FCV), which have regenerative brake-control systems. We applied a new logic to our robot that was developed in-house for conventional engine vehicles. We focused on braking deceleration of the regenerative brake control to change the operation timing from the accelerator pedal to the brake pedal. We verified the improvement of speed traceability of the driving robot installed with the proposed logic on the chassis dynamometer and test road.

An NMPC-Based Integrated Longitudinal and Lateral Vehicle Stability Control Based on the Double-Layer Torque Distribution.

With the ongoing promotion and adoption of electric vehicles, intelligent and connected technologies have been continuously advancing. Electrical control systems implemented in electric vehicles have emerged as a critical research direction. Various drive-by-wire chassis systems, including drive-by-wire driving and braking systems and steer-by-wire systems, are extensively employed in vehicles. Concurrently, unavoidable issues such as conflicting control system objectives and execution system interference emerge, positioning integrated chassis control as an effective solution to these challenges. This paper proposes a model predictive control-based longitudinal dynamics integrated chassis control system for pure electric commercial vehicles equipped with electro-mechanical brake (EMB) systems, centralized drive, and distributed braking. This system integrates acceleration slip regulation (ASR), a braking force distribution system, an anti-lock braking system (ABS), and a direct yaw moment control system (DYC). This paper first analyzes and models the key components of the vehicle. Then, based on model predictive control (MPC), it develops a controller model for integrated stability with double-layer torque distribution. The required driving and braking torque for each wheel are calculated according to the actual and desired motion states of the vehicle and applied to the corresponding actuators. Finally, the effectiveness of this strategy is verified through simulation results from Matlab/Simulink. The simulation shows that the braking deceleration of the braking condition is increased by 32% on average, and the braking distance is reduced by 15%. The driving condition can enter the smooth driving faster, and the time is reduced by 1.5 s~5 s. The lateral stability parameters are also very much improved compared with the uncontrolled vehicles.

Fuzzy Neural Network PID-Based Constant Deceleration Control for Automated Mine Electric Vehicles Using EMB System.

It is urgent for automated electric transportation vehicles in coal mines to have the ability of self-adaptive tracking target constant deceleration to ensure stable and safe braking effects in long underground roadways. However, the current braking control system of underground electric trackless rubber-tired vehicles (UETRVs) still adopts multi-level constant braking torque control, which cannot achieve target deceleration closed-loop control. To overcome the disadvantages of lower safety and comfort, and the non-precise stopping distance, this article describes the architecture and working principle of constant deceleration braking systems with an electro-mechanical braking actuator. Then, a deceleration closed-loop control algorithm based on fuzzy neural network PID is proposed and simulated in Matlab/Simulink. Finally, an actual brake control unit (BCU) is built and tested in a real industrial field setting. The test illustrates the feasibility of this constant deceleration control algorithm, which can achieve constant decelerations within a very short time and maintain a constant value of -2.5 m/s2 within a deviation of ±0.1 m/s2, compared with the deviation of 0.11 m/s2 of fuzzy PID and the deviation of 0.13 m/s2 of classic PID. This BCU can provide electric and automated mine vehicles with active and smooth deceleration performance, which improves the level of electrification and automation for mine transport machinery.

Development of a Dynamic Hitch Lift Controller using a Hybrid Control Strategy in A Heavy Combination Vehicle

This study presents a novel hybrid control strategy for the active hitch system, named the Dynamic Hitch Lift (DHIL), comprising a hybrid controller and a force actuator. The controller was designed to mitigate longitudinal load transfer in heavy combination vehicles by reducing the semitrailer pitch rate and rejecting the pitch moment, assisted by the virtual Skyhook moment. The new controller can calculate the desired force of the DHIL actuator to counter incoming load transfer during harsh braking exceeding 0.5 g braking deceleration. The proposed controller was assessed using a verified 12-degrees-of-freedom tractor-semitrailer model in harsh braking tests across different vehicle configurations. The first evaluation involved a stability test to demonstrate the stability of the controller in reducing load transfer across different vehicle configurations. The second evaluation was on controller performance, which revealed that the dynamic vehicle response has efficiently reduced load transfer by up to 9.14%. The third evaluation has focused on the DHIL actuator performance, which indicated that the actuator generated a force of 159,197 N, which translated into a stepper motor torque of 1,695 Nm at a speed of 1,000 rpm. Simulation results affirmed that the proposed DHIL controller was stable and could effectively reduce longitudinal load transfer in heavy combination vehicles during harsh braking.

Long Downhill Braking and Energy Recovery of Pure Electric Commercial Vehicles

The thermal decay of the brake has a great impact on the long downhill braking stability of pure electric commercial vehicles. Based on the road slope and using the fuzzy control method, the motor regenerative braking force and friction braking force distribution strategies were designed to reduce the friction braking force, improve the braking stability and recover the braking energy. By establishing road driving conditions with different slopes, numerical analysis methods are used to verify the proposed control strategy. The results show that the vehicle maintains a constant speed downhill at 30 km/h under the condition of 6% constant slope driving, and the braking energy recovery rate reaches 50.93% under 60% initial battery SOC, 50.89% under 70% initial battery SOC, and 50.81% under 80% initial battery SOC. The speed of the vehicle fluctuates slightly under the driving condition of an 18 km long variable slope distance, but the power torque of the electric mechanism can still be maintained at a constant speed of 30 km/h by adjusting the electric mechanism, and the braking energy recovery rate reaches 49.96%. During the downhill driving at a constant speed, the friction braking force does not participate in braking, and the recuperation rate of braking is determined by the slope and the magnitude of braking deceleration.

Intersection collision risk evaluation and active collision avoidance strategies for autonomous vehicles

In order to ensure that the autonomous vehicle can predict and taking actions to avoid the collision in time when facing the obstacles with intersection collision risk, an intersection collision risk prediction system is proposed in this paper, and two kinds of active obstacle avoidance strategies are designed according to the system: braking strategy and steering strategy. The position information of the obstacle is predicted by Fractional extended Kalman filter, the collision risk rate is determined by the time difference between the vehicle and the obstacle through the intersection point, and a neural network is trained to quickly give the collision risk of the vehicle and the obstacle. Braking strategy and steering strategy are formulated according to collision risk, the braking deceleration and Sigmoid path parameters are given. Finally, the simulation results of PreScan and MATLAB show that the collision risk prediction system can accurately predict the collision between vehicles and obstacles, the braking and steering strategies can effectively avoid the collision.

Research on the Failure Mechanism and Solution Strategy for Friction Braking of Electric Hoists

The electromagnetic braking motor, which combines cylindrical motors with electromagnetic brakes, has gradually been widely used in the lifting mechanism of electric hoists. This configuration of electric hoists usually has a large difference in lifting speed between fast and slow, and the highest speed can reach the lowest speed Liu Bei. During the process of rapid sudden braking and sudden switching between fast and slow speeds, it is easy to generate a large amount of braking slip, posing a huge challenge to friction braking. In response to the issue of excessive brake slip of a wire rope electric hoist, the mechanism causing the excessive brake slip was analysed, and a solution was provided. This paper analyses the methods of shortening braking time and reducing braking slip from mechanical, electrical, and control aspects, with a focus on the impact of rectifier and brake response delay on braking deceleration time and braking slip amount.

Research on anti-swing control of tower crane with lifting weight swing function

In order to ensure the accurate positioning of the assembly building, a swing trolley with swing function is designed. In order to solve the swing angle difference generated in the process of adjusting and positioning of the swing trolley, a simplified model is established to analyze the force and establish the relationship between the angular acceleration of the lower lifting beam and the angle of the swing. Secondly, the kinematic analysis is carried out for the rotating pendulum trolley, and its motion model is analyzed under uniform acceleration braking, uniform speed running and uniform deceleration braking. Finally, the angle difference of the rotating pendulum is gradually increasing in the case of different angular acceleration by example. And the variation of the rotating pendulum angle difference in different processes, laying the foundation for subsequent control studies.

Autonomous Vehicle Emergency Obstacle Avoidance Maneuver Framework at Highway Speeds

An autonomous vehicle (AV) uses high-level decision making and lower-level actuator controls, such as throttle (acceleration), braking (deceleration), and steering (change in lateral direction) to navigate through various types of road networks. Path planning and path following for highway driving are currently available in series-produced highly automated vehicles. In addition to these, emergency collision avoidance decision making and maneuvering are another key and essential feature that is needed in a series production AV at highway driving speeds. For reliability, low cost, and fast computation, such an emergency obstacle avoidance maneuvering system should use well-established conventional methods as opposed to data-driven neural networks or reinforcement learning methods, which are currently not suitable for use in highway AV driving. This paper presents a novel Emergency Obstacle Avoidance Maneuver (EOAM) methodology for AVs traveling at higher speeds and lower road surface friction, involving time-critical maneuver determination and control. The proposed EOAM framework offers usage of the AV’s sensing, perception, control, and actuation system abilities as one cohesive system to avoid an on-road obstacle, based first on performance feasibility and second on passenger comfort, and it is designed to be well integrated within an AV’s high-level control and decision-making system. To demonstrate the efficacy of the proposed method, co-simulation including the AV’s EOAM logic in Simulink and a vehicle model in CarSim is conducted with speeds ranging from 55 to 165 km/h and on road surfaces with friction ranging from 1.0 to 0.1. The results are analyzed and interpreted in the context of an entire AV system, with implications for future work.

Dynamic and Stationary Testing of Vehicle Braking Systems

Abstract The paper deals with the dynamic and stationary testing of vehicle braking systems for a selected set of eight intercity buses in an unloaded state. In case of the dynamic test carried out on a defined test area, a decelerometer is used to record the braking deceleration of a set of vehicles, which is placed in the vehicle during the course of test. According to the methodical procedure, the vehicle is accelerated to a speed of 40 km·h-1 and subsequently braked with the maximum braking deceleration. Braking deceleration values recorded by the decelerometer were used to calculate vehicle braking. During the stationary test, a roller brake tester was used, on which the maximum braking forces on the front and rear axles of the vehicle are measured, and then, the braking of the vehicle is calculated from these values according to the methodical procedure. The calculated braking values of vehicles during the dynamic and stationary test are subsequently compared, where it is possible to observe the percentage difference of these values, which may be caused by several factors taken into account in the results of the paper.

Analysis of Driver Departure and Damage in Frontal 100% Overlap Rigid Barrier Crash Conditions with AEB Intervention.

A braking robot and an in-vehicle HD camera were used to study the influence of emergency braking systems on the passive safety of vehicles, to conduct real vehicle tests on volunteers. The dynamic responses of 18 groups of volunteers under different braking deceleration speeds and different test speeds were collected, and the change rule of the driver’s forward tilt displacement during AEB braking was analyzed. The x-direction displacement of the head and shoulder of the volunteers increased with the increase of the braking deceleration speed, and there was no obvious correlation with the initial speed. Madymo was used to build a restraint system model, verified against the real vehicle crash test data. The maximum off-position state of the volunteer’s real car test was input into the restraint system model. The injury of drivers in frontal 100% overlap rigid barrier crash conditions with or without AEB effect was analyzed through simulation and comparison. It was concluded that AEB interventions do not increase the damage value with the existing passive safety development strategy.

Analyzing the Impact of C-ITS Services on Driving Behavior: A Case Study of the Daejeon–Sejong C-ITS Pilot Project in South Korea

This paper analyzes the impact of C-ITS service on driving behavior, focusing on a pilot project in Daejeon–Sejong, South Korea. C-ITS, an advanced technology, enables bidirectional wireless communication between vehicles or infrastructure, allowing for real-time traffic data collection and dissemination. The study uses a unique analytical method, employing parallel processing techniques for variable extraction and a paired t-test to examine the short-term effects of C-ITS on driving behavior. Findings indicate a significant change in drivers’ behavior, particularly in average speed, hard braking rate, severe deceleration rate, speeding rate, and excessive speeding rate, towards safer trends after receiving C-ITS warning services. Reductions in hard braking and severe deceleration were immediate after C-ITS service initiation, while a decrease in excessive speeding was observed after four months. Further research is needed to identify other potential influencing variables and provide an unbiased evaluation of C-ITS effectiveness. The study’s implications highlight its role in promoting public acceptance of C-ITS-service-based cooperative autonomous driving strategies.

Assessment of Driver Performance and Energy Efficiency in Transportation Tasks when Vehicle Weight Undergoes Significant Changes

The results of the analysis of the operation of heavy-duty vehicles with high load capacity (tractor units with trailers) have been presented. The road transport of cargo relies heavily on vehicles of this type. Performing this role is associated with high energy consumption. Laden and unladen driving were investigated. The collected data guaranteed the constancy of numerous parameters, including the investigation of the same model vehicles under both loaded and unloaded conditions on identical roads. The assessment focused on changes in driving techniques and energy consumption during significant variations in vehicle weight. The evaluation was grounded in the measurement results of kinematic parameters, namely driving speed, acceleration, and braking deceleration. The aforementioned parameters are typically employed in analysing driving techniques (DBP—driver behaviour profile). The energy consumption of traffic was then assessed in light of the analysed changes in driving technique. The weight of the load was 24 t, increasing the weight of the vehicle by 175%. The increase in weight has caused a 68.4% increase in the energy required for driving. The change in vehicle mass has a relatively minor effect on the average, median, and modal values of driving speed. In contrast, the impact on acceleration is far greater. This is partly because the examined models of tractor units are equipped with high-power engines (420 hp). Furthermore, 81% of the roads used for transportation tasks are motorways and expressways.

Does ABS ensure good performance in emergency braking for less skilled motorcyclists?

This study aims to investigate whether motorcyclists are able to use the full potential of anti-lock braking systems (ABS) in demanding braking situations that maintain the natural coupling of action and perception of emergency events, or whether instead the lack of braking skills in riders makes ABS almost ineffective and comparable to non-ABS brakes on dry pavement. Six experienced riders performed two experimental tests. First test included 12 emergency braking trials in a realistic scenario using a mock-up of an intersection conflict with a car initiating a left turn manoeuvre across the path (LTAP) of a motorcycle approaching from the opposite direction as an unpredicted moving hazard. Second test included three trials in a planned self-timed hard braking. The speed at the onset of braking was 35–45 km/h. The braking performance was measured from the initiation of brake pressure until the full stop of the vehicle. Front wheel ABS usage was determined by the pressure in the master cylinder and wheel callipers. The testing resulted in 85 data runs with full stop braking manoeuvres.Results revealed four categories of riders classified by their front wheel ABS usage during the emergency braking tests, which included two riders who underused front wheel ABS (9.6% and 27.4% of braking time on average). The worst case resulted in a significantly longer braking distance (braking deceleration of 5.2 m/s2). The highest skilled rider, who reached initial jerks close to 30 m/s3, used the ABS of the front wheel 93.7% of the braking time on average, resulting in a braking deceleration of 7.71 m/s2. Overall, the best braking performance was achieved in trials where the front ABS was activated for more than 80% of the braking. In planned self-timed hard braking test, where riders have more time to plan the braking manoeuvre, the experience rider with lowest performance during the emergency braking test improved braking efficiency and was able to increase ABS activation from 9.6% to 26.8% of the time, achieving a deceleration of 6.24 m/s2.ABS is demonstrated to reduce stopping distances and to improve stability under all braking conditions, but such features are not enough to guarantee a good braking performance in emergency events if the riders have not the skills to utilize the full braking power of the motorcycle. Less skilled riders, even with ABS, may not have the confidence to increase braking power further when reaching high decelerations that push them to the limit of their stabilisation control in emergency braking, thus increasing braking distance with potentially life-threatening consequences. Our results suggest that many experience riders still need knowledge and skill to make the ABS work to its optimum in emergency events to avoid crashes. Further research with larger sample sizes including the full diversity of the motorcyclist population is recommended to determine the actual proportion of motorcyclists underusing ABS.

Research on Hierarchical Control Strategy of Automatic Emergency Braking System

In order to improve the active safety of vehicles, the control strategy of the vehicle automatic emergency braking system is studied. The hierarchical control idea is used to model the control strategy. The upper controller is a collision time model for the decision-making of vehicle braking deceleration, and the collision time threshold is determined under the condition of considering comfort. According to the braking deceleration output by the upper controller, the lower controller controls the vehicle by adjusting the throttle opening and braking pipeline pressure through PID control. Based on the typical test conditions of C-NCAP, a joint simulation test of CarSim and Matlab/Simulink for hierarchical control strategy is carried out. In order to achieve further verification, several groups of test conditions are conducted, and finally its effectiveness is verified, which can ensure the safety of drivers.

A Practical Deceleration Control Method, Prototype Implementation and Test Verification for Rail Vehicles

Currently, the theoretical braking force control mode, characterized by actual deceleration as an unstable open-loop output, is the most widely used brake control mode in trains. To overcome the shortcomings of non-deceleration control modes, a deceleration control mode is proposed to realize the closed-loop control of train deceleration. First, a deceleration control algorithm based on parameter estimation was derived. Then, the deceleration control software logic was designed based on the existing braking system to meet the engineering requirements. Finally, the deceleration control algorithm was verified through a ground combination test bench with real brake control equipment and pneumatic brakes. The test results show that the deceleration control can make the actual braking deceleration of the train accurately track the target deceleration in the presence of disturbances, such as uncertain brake pad friction coefficients, line ramps, vehicle loads and braking force feedback errors, as well as their combined effects, and does not affect the original performance of the braking system. The average deceleration in the deceleration control mode is relatively stable, and the control error of instantaneous deceleration is smaller.

Research on Safe Following Distance on an Expressway Based on Braking Process Analysis

As an important part of the vehicle active collision avoidance system, improvement of the minimum safe following distance model has aroused the interest of researchers at home and abroad. According to the characteristics of the safe driving of vehicles on expressways, the braking process of vehicles is analyzed using the principle of kinematics. According to the requirements of the safe following distance between vehicles, the safe following distance of different braking system structures, different following states, different speeds and different slope sections on expressways is quantitatively analyzed. Three different safe following distance calculation methods based on braking deceleration under different slope conditions are established. Matlab software was used for simulation analysis. The simulation results show that the calculation method of the safe following distance meets the requirements of keeping safe distance in the Implementation Regulations of Road Traffic Safety Law of the People’s Republic of China and provides a more specific reference basis for speed limit used on expressways. This study provides a theoretical basis for the application and interpretation of the parking sight distance value stipulated in the Design Specification for Highway Alignment, and has certain practical guiding significance for improving the density and transportation efficiency of expressway vehicles and reducing the incidence of rear-end traffic accidents.

Investigation on AEB Key Parameters for Improving Car to Two-Wheeler Collision Safety Using In-Depth Traffic Accident Data

Automatic emergency braking (AEB) system play an essential role in avoiding traffic collisions and minimizing impact strengths, which contributes to improving road traffic safety. However, the present research of the AEB system is mainly concentrated on avoiding the car to car and car to pedestrian collisions. China has typical mixed traffic characteristics, especially the frequent car to two-wheeler collision accidents. Research on the AEB system to prevent car to two-wheeler collisions in complex multi-traffic scenarios is of great significance to further improve the comprehensive performance of the AEB system. In this article, based on the cases of the car to two-wheeler collisions from China In-Depth Accident Study (CIDAS) database, the effects of three key parameters of the AEB system, braking deceleration, braking advance time, and detection range, on the accident rate and severity are studied by accident reconstruction and virtual experiment. Results show that the theoretical optimal detection range of the AEB system is 180°–35 m for the car to two-wheeler collision prevention. Moreover, the current feasible optimal detection range is 120°–35 m due to the limitation of environmental awareness technology. When the braking advance time is 1 s, the detection angle is 120°, and the detection distance is 35 m, the installation of the AEB system can avoid 22.3% of the car to two-wheeler collision accidents. Meanwhile, in the inevitable accidents, the average collision speed of vehicles decreases from 33.93 to 21.34 km/h, which effectively reduces the collision strengths. Findings of this study could help car manufacturers and makers of AEB hardware select the appropriate detection radar. They can also provide ideas and data support for formulating relevant laws and regulations of the AEB system, future development of AEB system, or other driver assistance systems.