Slippery Road Surface Research Articles

外乱オブザーバとすべり制御による全方向移動ロボットの移動補正

Recently, the robots which work in a hospital and factory have developed. The robot is expected to omni-directional motion to move in limited space. For a Mecanum wheels to be used in the wheels of the omni-directional mobile robot has a complex structure, depending on the situation of the road surface lose stability, movement is difficult. Also, due to the movement on the assumption of slip control becomes to be difficult with slippery road surface. In this study, the development of the omni-directional whole direction mobile robot equipped with a Mecanum wheels. And in order to improve the motion of the efficiency, it performs a slip correction and disturbance observer, to verify the running performance in the actual road surface.

A Study of Coordinated Vehicle Traction Control System Based on Optimal Slip Ratio Algorithm

Under complicated situations, such as the low slippery road surface and split-μroad surface, traction control system is the key issue to improve the performance of vehicle acceleration and stability. In this paper, a novel control strategy with engine controller and active pressure controller is presented. First and foremost, an ideal vehicle model is proposed for simulation; then a method for the calculation of optimal slip ratio is also brought. Finally, the scheme of control method with engine controller and active brake controller is presented. From the results of simulation and road tests, it can be concluded that the acceleration performance and stability of a vehicle equipped with traction control system (TCS) can be improved.

2P1-T09 平面正八角形構造をした劣駆動歩行ロボットの開発と基礎実験

This paper proposes a novel underactuated locomotion robot that has high stiffness and reproduces the gait property equivalent to an eight-legged rimless wheel walking on a slippery road surface. First, we describe the overview of the experimental machine we developed and its mechanical features. Second, we develop the equations of motion and collision for the ideal model with small passive rollers, and discuss the collision dynamics for stance-leg exchange with the prospect of transition to non-instantaneous double-support motion. Third, we perform numerical simulations to understand the fundamental properties of the gait rolling on a rigid road surface, and discuss its similarity to limit cycle walking on a slippery road surface.

The Contribution of Safe Driving Training in Educating Drivers to Risk Perception

The influence of safe-driving training on risk perception is not widely investigated actually. Aim of the present work is to examine if an increase in self-confidence and perception of ability, resulting from a safe-driving training, is associated to an increase in risk perception and awareness. 228 subjects took part in an eight-hours safe-driving training including four driving exercises, simulating risk situations in everyday driving contexts, such as someone suddenly crossing the road or driving on slippery road surface. Before and after the training, all the subjects were submitted a questionnaire to test the risk perception in everyday driving environment (RIPAQ, Risk Perception in Action Questionnaire). Repeated measures ANOVA showed a significant increase in the estimate of risk incidental to some situations, like “using your mobile while driving”, “not fastening the lifebelt” or “driving at a speed of 60km/h in the city center”, but not to other ones, as “avoiding slowing down next to a cross road”. Data are discussed in the light of the dual process theory about risk perception: the emotional component seems to be more aroused by the safe-driving experience than the analytic one.

Aggravating and mitigating factors associated with cyclist injury severity in Denmark

Introduction: Denmark is one of the leading cycling nations, where cycling trips constitute a large share of the total trips, and cycling safety assumes a top priority position in the agenda of policy makers. The current study sheds light on the aggravating and mitigating factors associated with cyclist injury severity on Danish roads by examining a comprehensive set of accidents involving a cyclist and a collision partner between 2007 and 2011. Method: This study estimates a generalized ordered logit model of the severity of cyclist injuries because of its ability to accommodate the ordered-response nature of severity while relaxing the proportional odds assumption. Results: Model estimates show that cyclist fragility (children under 10years old and elderly cyclists over 60years of age) and cyclist intoxication are aggravating individual factors, while helmet use is a mitigating factor. Speed limits above 70–80km/h, slippery road surface, and location of the crash on road sections are aggravating infrastructure factors, while the availability of cycling paths and dense urban development are mitigating factors. Heavy vehicle involvement and conflicts between cyclists going straight or turning left and other vehicles going straight are aggravating vehicle involvement factors. Practical applications: The results are discussed in the context of applied policies, engineering, and traffic management solutions for bicycle safety in Denmark.

Modeling, control and analysis of limit cycle walking on slippery road surface

This paper investigates the feasibility and fundamental gait properties of active and passive limit-cycle walkers that walk on slippery road surface. First, we introduce the model of an underactuated spoked walker with a torso and mathematically analyze the collision model on the assumption of sliding contact with the ground to identify the condition for achieving instantaneous stance-leg exchange. Second, we develop the equation of motion incorporating sliding friction acting on the stance-leg-end and numerically show that the walker can generate a stable walking gait by applying a simple control of the torso. Furthermore, we discuss the case of passive dynamic walking on slippery slope using the same model but without considering the torso dynamics.

Variable Gear Ratio Control Using Vehicle Body Slip Angle

Vehicles with variable steering characteristics have long been studied and compared with those having typical fixed gear ratio steering, and the variable gear ratio properties are reported to have improved maneuverability and stability in high-speed lane changes and on slippery low-friction road surfaces. However, it is not clear how gear ratios should be set for individual vehicle characteristics. Therefore, the present study has investigated a variable steering gear system using body slip angle feedback for the purpose of improved maneuverability and stability in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range. The results of a driving simulator experiment show that the steering effect improves and maneuverability and stability increase in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range by applying linear-variable control to the steering ratio from a body slip angle of 5?. This result is seen both in double lane changes, such as in hazard avoidance, and in J-turns with long drifting. Moreover, it shows an improvement in drift controllability through prompt countersteering. Overall, the present system can enhance the driver’s hazard avoidance capability.

Bus accident severity and passenger injury: evidence from Denmark

Bus safety is a concern not only in developing countries, but also in the U.S. and Europe. In Denmark, disentangling risk factors that are positively or negatively related to bus accident severity and injury occurrence to bus passengers can contribute to promote safety as an essential principle of sustainable transit and advance the vision “every accident is one too many”. Bus accident data were retrieved from the national accident database for the period 2002–2011. A generalized ordered logit model allows analyzing bus accident severity and a logistic regression enables examining occurrence of injury to bus passengers. Bus accident severity is positively related to (i) the involvement of vulnerable road users, (ii) high speed limits, (iii) night hours, (iv) elderly drivers of the third party involved, and (v) bus drivers and other drivers crossing in yellow or red light. Occurrence of injury to bus passengers is positively related to (i) the involvement of heavy vehicles, (ii) crossing intersections in yellow or red light, (iii) open areas, (iv) high speed limits, and (v) slippery road surface. The findings of the current study provide a comprehensive picture of the bus safety situation in Denmark and suggest the necessity of further research into bus drivers’ attitudes and perceptions of risks and road users’ perceptions of bus operations. Moreover, these findings suggest the need for further training into bus drivers’ hazard recognition skills and infrastructural solutions to forgive possible driving errors.

A non-linear model-based slip controller for electropneumatic brakes in heavy commercial vehicles

Heavy commercial vehicles are commonly equipped with an air brake system. Under panic braking or braking on slippery road surfaces, some wheels of the vehicle may get locked, resulting in the loss of vehicle stability or steerability. An Antilock Braking System (ABS) prevents the wheels from locking, and ensures vehicle stability and steerability. The actual control algorithms of commercially available ABS are proprietary and might have required extensive experimental calibration. This paper presents a model-based slip control scheme to prevent locking of wheels by regulating the brake chamber pressure, and this has been implemented in an experimental setup.

Development of Antilock Braking System Based on Various Intelligent Control System

This paper presents about the development of an Antilock Braking System (ABS) using quarter vehicle model and control the ABS using different type of controllers. Antilock braking system (ABS) is an important part in vehicle system to produce additional safety for drivers. In general, Antilock braking systems have been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking especially on slippery road surfaces. In this paper, a variable structure controller has been designed to deal with the strong nonlinearity in the design of ABS controller. The controllers such as PID used as the inner loop controller and Fuzzy Logic as outer loop controller to develop as ABS model to control the stopping distance and longitudinal slip of the wheel.

RESEARCH INTO AUTOMOBILE MOVEMENT ON A CURVE UNDER WINTER CONDITIONS / AUTOMOBILIO JUDĖJIMO POSŪKYJE TYRIMAS ŽIEMOS SĄLYGOMIS

The article analyzes the movement of the car on the curve on the slippery and snowy road surface with asphalted ruts. The paper reviews literature related to lateral and longitudinal vehicle acceleration and dynamics of vehicle movement. The experimental facts of vehicle lateral acceleration are given in graphical charts. The article also describes the acceleration values and stability of the automobile depending on the speed in the curve. The findings are given based on the results. Santrauka Straipsnyje nagrinėjamas automobilio judėjimas posūkyje esant slidžiai ir snieguotai su asfaltuotomis provėžomis kelio dangai. Apžvelgiama literatūra, susijusi su automobilių skersiniais ir išilginiais pagreičiais, automobilių judėjimo dinamika. Eksperimentinėje dalyje pateikiami automobilių skersinių pagreičių grafikai. Nagrinėjamas pagreičių dydis ir automobilio stabilumas priklausomai nuo judėjimo greičio tame kelio posūkyje. Remiantis gautais rezultatais pateikiamos išvados.

A Study of Vehicle Dynamics Stability Based on Fuzzy Control

Electronic Stability Program (ESP) has become the focus of the study in the field of automotive active safety and chassis control in recent years, which was developed from ABS and TCS. ESP mainly works through adjusting the size and the distribution of the longitudinal tire force. ESP can make vehicle produce effective yaw moment to restrain oversteering or understeering, However, ESP is a typical nonlinear, time-delay, time-varying parameter system and its mathematical model is very complex. It is difficult to design the control model by traditional control theory. Fuzzy control does not depend on a precise mathematical model. It is employed to handle complicated questions of nonlinear dynamics. First, in this paper, the7-DOF of vehicle dynamics model based on the H. B. Pacejka tyre model (magic formula) and vehicle reference model were established by using the MATLAB/SIMULINK. Then by using fuzzy control principle to direct at the nonlinear, time varying characteristics of the ESP system, a controller of yaw rate based on fuzzy control was designed. An analysis of the simulation results of J-turn and lane change on slippery road surface shows that the present stability control system based on the yaw rate is effective in maintaining the yaw rate and the sideslip angle within the optimal range, thus improving the vehicle stability.

Tyre friction behaviour under abrupt wheel torque transients on slippery road surfaces: experimental analysis and modelling

The paper shows that, during abrupt wheel torque transients for ice surface and low vehicle speeds, the tyre can develop significantly larger longitudinal force than the peak value of the tyre static curve. This so-called dynamic tyre friction potential (DTFP) effect has many influencing factors such as the rate of change of the wheel torque, the vehicle speed, and the tyre dwell time. The paper presents a detailed analysis of the DTFP behaviour based on the experimental data collected by using an in-wheel motor-based tyre test vehicle. The analysis results and an insight into the brush structure of a tyre model lead to the hypothesis that the different influencing factors may be predominantly explained by the bristle dwell time (BDT) effect. Following this hypothesis, the LuGre model of the tyre friction dynamics is extended with a physical BDT sub-model. The experimental validation results show that the proposed model can accurately capture the low-speed tyre–ice friction behaviour during abrupt wheel torque transients.

Closed-loop snowplow applicator control using road condition measurements

Closed-loop control of a snowplow applicator, based on direct measurement of the road surface condition, is a valuable technology for the optimisation of winter road maintenance costs and for the protection of the environment from the negative impacts of excessive usage of de-icing chemicals. To this end, a novel friction measurement wheel is designed to provide a continuous measurement of road friction coefficient, which is, in turn, utilised to control the applicator automatically on a snowplow. It is desired that the automated snowplow applicator deploy de-icing materials right from the beginning of any slippery surface detected by the friction wheel, meaning that no portion of the slippery road surface should be left untreated behind, as the snowplow travels over it at a reasonably high speed. This paper describes the developed wheel-based measurement system, the friction estimation algorithm and the expected performance of the closed-loop applicator system. Conventional and zero velocity applicators are introduced and their hardware time delays are measured in addition to the time delay of the friction estimation algorithm. The overall performance of the closed-loop applicator control system is shown to be reliable at typical snowplowing speeds if the zero velocity applicator is used.

INTELLIGENT BRAKING SYSTEM USING FUZZY LOGIC AND SLIDING MODE CONTROLLER

In this paper, an antilock–antiskid braking system controller, which has been designed for stability enhancement of vehicles during braking and turning, is presented. Using available signals, a novel structure is proposed for vehicle stability improvement for critical driving conditions such as braking on slippery or µ-split road surfaces. In conventional vehicles, undesired lane changes may occur due to equal dispatch of braking torques to all wheels simultaneously. Also, intensive pressure on brake pedal can bring about wheel lockup which results in vehicle instability and undesired lane changes. Antilock braking system (ABS) along with Antiskid braking system (ASBS) can serve as a driver-assistance system in vehicle path correction facing critical driving conditions during braking and turning round on different road surfaces. For these purposes, at first, a trained Neuro-Fuzzy estimator is used for vehicle path prediction according to vehicle’s speed, applied steering angle and their changes. Then, slip of each wheel will be controlled by an antilock fuzzy controller which has been designed for each wheel. Also, a sliding mode controller has been designed so as to control the yaw angle considering the yaw error, where the yaw error is resulted from the difference of the Neuro-Fuzzy estimator’s output and actual yaw angle. Then, the difference of the left and the right wheels’ braking torques are used by the sliding mode controller in order to reduce the yaw error. Considering a model of three-degreeof-freedom for chassis and one-degree-of-freedom Dugoff’s tire model for each wheel, a series of Matlab/Simulink simulation results will be presented to validate the effectiveness of the proposed controller. Finally, a comparison will be made between the proposed method and one of the recent control systems which shows the superiority of its performance.

Analyses of Factors of Crash Avoidance Maneuvers Using the General Estimates System

Objective. Taking an effective corrective action to a critical traffic situation provides drivers an opportunity to avoid crash occurrence and minimize crash severity. The objective of this study is to investigate the relationship between the probability of taking corrective actions and the characteristics of drivers, vehicles, and driving environments. Methods. Using the 2004 GES crash database, this study classified drivers who encountered critical traffic events (identified as P_CRASH3 in the GES database) into two pre-crash groups: corrective avoidance actions group and no corrective avoidance actions group. Single and multiple logistic regression analyses were performed to identify potential traffic factors associated with the probability of drivers taking corrective actions. Results. The regression results showed that the driver/vehicle factors associated with the probability of taking corrective actions include: driver age, gender, alcohol use, drug use, physical impairments, distraction, sight obstruction, and vehicle type. In particular, older drivers, female drivers, drug/alcohol use, physical impairment, distraction, or poor visibility may increase the probability of failing to attempt to avoid crashes. Moreover, drivers of larger size vehicles are 42.5% more likely to take corrective avoidance actions than passenger car drivers. On the other hand, the significant environmental factors correlated with the drivers' crash avoidance maneuver include: highway type, number of lanes, divided/undivided highway, speed limit, highway alignment, highway profile, weather condition, and surface condition. Some adverse highway environmental factors, such as horizontal curves, vertical curves, worse weather conditions, and slippery road surface conditions are correlated with a higher probability of crash avoidance maneuvers. These results may seem counterintuitive but they can be explained by the fact that motorists may be more likely to drive cautiously in those adverse driving environments. Conclusions. The analyses revealed that drivers' distraction could be the highest risk factor leading to the failure of attempting to avoid crashes. Further analyses entailing distraction causes (e.g., cellular phone use) and their possible countermeasures need to be conducted. The age and gender factors are overrepresented in the “no avoidance maneuver.” A possible solution could involve the integration of a new function in the current ITS technologies. A personalized system, which could be related to the expected type of maneuver for a driver with certain characteristics, would assist different drivers with different characteristics to avoid crashes. Further crash database studies are recommended to investigate the association of drivers' emergency maneuvers such as braking, steering, or their combination with crash severity.

On-board road condition monitoring system using slip-based tyre-road friction estimation and wheel speed signal analysis

This paper presents an on-board road condition monitoring system. The road condition is continuously evaluated in terms of slipperiness and coarseness and is classified into four grades, normal (μmax ≤ 0.5), slippery (0.3 ≤ μmax< 0.5), very slippery (μmax< 0.3), and rough surface (gravel). A non-linear curve fitting technique is adopted to estimate the maximum tyre-road friction coefficient using the so-called ‘magic formula’. The characteristic of the relationship between friction coefficient and slip, i.e. the value of maximum friction coefficient μmax varies significantly with different surfaces, but its corresponding slip value λmax does not vary much, is exploited in the road condition classification algorithm. For surface coarseness analysis, a separate classifier based on the variance of filtered wheel speed signal is implemented. Experimental results demonstrate the feasibility of the road condition monitoring system for detecting slippery and rough road surfaces in close to real-time. In addition, the proposed slip-based friction estimation algorithm has the merits of robustness to vehicle-tyre variance and easy calibration as opposed to past slip-based friction estimation approaches in the literature.

Design of an Optimal Fuzzy Controller for Antilock Braking Systems

Antilock braking systems (ABSs) have been developed to improve vehicle control during sudden braking, especially on slippery road surfaces. The objective of such control is to increase wheel traction force in the desired direction while maintaining adequate vehicle stability and steerability and reducing the vehicle stopping distance. In this paper, an optimized fuzzy controller is proposed for ABSs. The objective function is defined to maintain the wheel slip to a desired level so that maximum wheel traction force and maximum vehicle deceleration are obtained. All the components of a fuzzy system are optimized using genetic algorithms. The error-based global optimization approach is used for fast convergence near the optimum point. Simulation results show fast convergence and good performance of the controller for different road conditions

Analyses of Rear-End Crashes Based on Classification Tree Models

Objective. Signalized intersections are accident-prone areas especially for rear-end crashes due to the fact that the diversity of the braking behaviors of drivers increases during the signal change. The objective of this article is to improve knowledge of the relationship between rear-end crashes occurring at signalized intersections and a series of potential traffic risk factors classified by driver characteristics, environments, and vehicle types. Methods. Based on the 2001 Florida crash database, the classification tree method and Quasi-induced exposure concept were used to perform the statistical analysis. Two binary classification tree models were developed in this study. One was used for the crash comparison between rear-end and non-rear-end to identify those specific trends of the rear-end crashes. The other was constructed for the comparison between striking vehicles/drivers (at-fault) and struck vehicles/drivers (not-at-fault) to find more complex crash pattern associated with the traffic attributes of driver, vehicle, and environment. Results. The modeling results showed that the rear-end crashes are over-presented in the higher speed limits (45–55 mph); the rear-end crash propensity for daytime is apparently larger than nighttime; and the reduction of braking capacity due to wet and slippery road surface conditions would definitely contribute to rear-end crashes, especially at intersections with higher speed limits. The tree model segmented drivers into four homogeneous age groups: < 21 years, 21–31 years, 32–75 years, and > 75 years. The youngest driver group shows the largest crash propensity; in the 21–31 age group, the male drivers are over-involved in rear-end crashes under adverse weather conditions and the 32–75 years drivers driving large size vehicles have a larger crash propensity compared to those driving passenger vehicles. Conclusions. Combined with the quasi-induced exposure concept, the classification tree method is a proper statistical tool for traffic-safety analysis to investigate crash propensity. Compared to the logistic regression models, tree models have advantages for handling continuous independent variables and easily explaining the complex interaction effect with more than two independent variables. This research recommended that at signalized intersections with higher speed limits, reducing the speed limit to 40 mph efficiently contribute to a lower accident rate. Drivers involved in alcohol use may increase not only rear-end crash risk but also the driver injury severity. Education and enforcement countermeasures should focus on the driver group younger than 21 years. Further studies are suggested to compare crash risk distributions of the driver age for other main crash types to seek corresponding traffic countermeasures.

Advanced motion control of electric vehicle with fast minor feedback loops: basic experiments using the 4-wheel motored EV “UOT Electric March II”

Electric motors in electric vehicles (EVs) has quite fast torque response, thus fast minor feedback loops can be applied for vehicle motion stabilization. This paper clarified that such feedback loop can stabilize the dynamics of driven wheel on the slippery road surface. With such loop, driven wheel has large inertia equivalently. It can stabilize the vehicle's lateral dynamics, if minor feedback loops are independently installed in the driven wheels. This effect was demonstrated with simulations and experiments. It suggests the effectiveness of minor feedback loops in the total control system like direct yaw moment control (DYC). This paper also introduces our novel 4-motored EV “UOT Electric March II”, which is newly constructed for these experiments.