Uneven Road Surface Research Articles

A BASIC STUDY ON RIDE COMFORT EVALUATION BASED ON BIOSIGNALS

In this research, biosignals, heart rate and skin conductance response, were discussed as indices for the evaluation of ride comfort. A driving simulator that reproduces the behavior of vehicles traveling on uneven road surfaces was used for subjective evaluation of the road profile. At the same time, the fluctuations in the heart rate and skin conductance response were measured. From the results, it was found that the test subject's heart rate increased when driving on the uneven roads, and as the vertical acceleration R.M.S. value increased, the variability of heart rate increased. Moreover, it was also confirmed that the test subject's skin conductance response increased when driving on the uneven roads, but there was no significant relations between the vertical acceleration R.M.S. value and variability of skin conductance response.

Full Bicycle Dynamic Model for Interactive Bicycle Simulator

Abstract An interactive bicycle simulator with six degrees of freedom motion system could bring the rider a very realistic riding feeling. An important component of the simulator is the full bicycle dynamic model that simulated the two-wheeled bicycle dynamics. It consists of two slightly coupled submodels: The stability submodel and the vibration submodel. The stability submodel solves the stability of the bicycle under rider’s active maneuvers and the vibration submodel evaluates the vibration response of the bicycle due to uneven road surface. The model was validated by several experiments and successfully applied to the interactive bicycle simulator.

Numerical simulation of the stress on exhaust systems due to road surface unevenness

Numerical simulation allows the stress on an exhaust system under engine excitation to be determined independently of experimental investigations. Numerical simulation methods are therefore a suitable means of identifying and optimising strength-critical areas of an exhaust system in a development phase in which components or prototype engines are not yet available. Until now, however, the stress caused by uneven road surfaces has only been determined by approximation on the basis of statistical substitute loads and then confirmed experimentally in a later development phase by taking measurements on an actual vehicle. Therefore, the numerical optimisation of an exhaust system under “uneven road surface” loading is possible only to a limited extent. This article presents a method that allows the stress on an exhaust system caused by uneven road surfaces to be calculated even at an early development phase by means of numerical simulation.

Adaptive elastomeric mount

Engine mounting should isolate the unevenness of road surface and the vibration movement, which is caused by engine excitation. At the same time it should provide a firm connection between engine and carriage. With the solution, namely, amplitude dependant stiffness and damping, a new adaptive elastomeric mount has been developed. This new mount clearly improves the noise- and vibration comfort in vehicle.

05/00394 An environmental and economic assessment of mopeds in Denmark: Saxe, H. International Journal of Environmental Technology and Management, 2003, 3, (3/4), 349–367

Course holding by cyclists and moped riders includes both steering alongside a course and stabilising the vehicle. Inability to hold course may lead to conflicts with other road users. To design safe bicycle and moped facilities, and to consider the safety of those existing, knowledge about performance during course holding is necessary. Based on a literature survey, the article discusses how course holding will be influenced by characteristics of the course, the vehicle and the rider. Effects of disturbing factors such as side-wind and road-surface unevenness are also described. In a field study subjects carried out riding tests with various models of bicycles and mopeds on three courses. Speed, riding with one hand on the handlebars, side-wind and road-surface unevenness were included as independent variables.Results indicate that cyclists and moped riders need a width of at least 1 m on straight roads. At intersections this width should be at least 1.25 m. Performance in the tests also showed differences between vehicle models and modes of riding.

New Method to Assess Ride Safety on Uneven Element Pavements

Stone element pavements are typical of many historical urban centers in Europe. Unfortunately, their deterioration due to traffic causes severely uneven road surfaces, compromising the safety of those who ride on two-wheeled vehicles. The writers have developed a method to quantify the danger level in relation to actual road conditions by creating a mechanical model able to simulate two-wheeled vehicles on road discontinuities. Several combinations of road discontinuities and approach speeds were tested in order to determine transit safety. These model discontinuities, varying in kind and magnitude, were examined using both rectilinear trajectories and curves. Specific criteria and related thresholds were set up to identify hazardous situations. This method was used on stone element pavements with embedded tram tracks. The level of danger for each condition was thus evaluated using these criteria. Finally, we listed in a table the thresholds for the acceptable pavement discontinuities in order to formulate suggestions for maintenance management and speed limitations.

Effect of driver behaviour, driving events and road type on the stability and resting behaviour of sheep in transit

AbstractThe aim of this project was to examine the relationships between driver behaviour and driving events during a journey and the behavioural responses of sheep to these events. Driving style can have a major influence on the welfare of the animals by affecting the risk of injury and by disturbing the ability of the sheep to rest. Two drivers each drove groups of 10 sheep in a 5·5-tonne, single-deck, non-articulated livestock vehicle on five 7-h road journeys consisting of minor roads, main single carriageways and a motorway. The driver, the driver’s view through the windscreen, the speedometer and the sheep were video recorded. Differences in driving style were identified as differences in vehicle speed, rapid braking and the number of corners taken with high cornering g-force. Differences in driving style had a slight effect on the frequency of losses of balance by the sheep and a more significant effect on the degree of disturbance to the sheep and on their ability to rest during the journey. Losses of balance were common, but falls were rare. About 80% of the losses of balance could have been caused by driving events, such as acceleration, braking, stopping, cornering, gear changes and uneven road surfaces. Only about 22% of driving events were followed by a loss of balance. It is likely that driving events were also responsible for many interruptions to both lying behaviour and rumination. Clear benefits of motorway driving compared with single carriageway driving were fewer losses of balance, more lying down, more rumination and fewer disturbances amongst the sheep. This study provides evidence that would be useful for driver training and education to promote careful driving as a means of ensuring the welfare of animals in-transit. The quality of the journey experienced by sheep during transport is dependent upon a number of factors that can be influenced by the driver of the vehicle.

Error Sources When Land Vehicle Dead Reckoning with Differential Wheelspeeds

ABSTRACT: This paper compares a differential wheelspeed–based dead-reckoning system with a gyro-based system for land navigation. Test results show that the two schemes perform equally well when modeling assumptions hold, such as when navigating smooth road surfaces. However, the wheelspeed-heading estimator's position errors grow about twice as fast as the gyro-based system's when navigating speed bumps and uneven road surfaces. In contrast to statements made in the literature, increasing the resolution of the stock wheelspeed sensors by an order of magnitude does not increase the positioning accuracy of either estimator, and longitudinal slip of the vehicle tires does not appear to be a dominant error source. Ultimately, the limiting factor for dead-reckoning performance appears to be road surface unevenness.

Handling characteristics on uneven road surface in a turn

Handling characteristics on uneven road surface in a turn

Control of Vehicle Maneuverability and Stability by Means of Attitude Control with Vertical Load Control.

Active control of maneuverability and stability of a vehicle on uneven roadways is studied in the case of vertical load control as well as attitude control. It is well known that the dynamic responses of chassis on the uneven road surface have large effect on the vehicle cornering properities. In the previous study, the authors investigated that the attitude control by active suspension was effective to improve vehicle stability in cornering on uneven road surface. However, the effect on stability is sufficient only in lower frequency range of vertical motion of sprung mass. In this paper, the effects of vertical load control in consideration of unsprung masses are clarified by numerical simulations for further improvement of maneuverability and stability.

Influence of Attitude Control by Active Controlled Suspension on Stability of Vehicle.

Active control of maneuverability and stability of a vehicle on uneven roadways by attitude control with active suspension is studied in this paper. It is well know that the stability against external disturbance due to uneven road surface is one of the most important items regarding maneuverability and stability. A half car model with active suspension is, in this report, used for pitching and bouncing motions, and a two-wheeler model of front steering type is provided for lateral and yawing motions. The influence of pitching motion of vehicle body on stability is obtained by these models. After that, the effects of attitude control of active suspensions with optimal controller on vehicle stability are clarified, for cornering maneuver on uneven road surface.

Biaxial Vehicle Motion Simulation and Animation

This paper presents two simulation models which describe the motion and dynamics of biaxial vehicles: a passenger car and 112 ton truck on even and uneven road surfaces. Based on simulation results, original graphical postprocessor presents animation of vehicle motion in assumed scenery including other vehicles. (A) For the covering abstract of the symposium see IRRD 882950.

Theory of Active Suspension Design

Active suspension design has been developed as the application of optimal control theory. However, optimal control theory is only suitable for the design of regulator, where transient responses starting from any initial state are required to converge to zero. The active suspension system is not a simple regulator because road surface unevenness acts only as disturbance in the low frequency range, while it acts not only as disturbance but also as reference signal in the high frequency range. Thus, optimal control theory is not considered suitable for active suspension design. As an alternative to optimal control theory, a new design theory based on exact model matching (EMM) with a disturbance predictor is developed in this paper. One of the peculiarities of this problem is the need to prepare a separate control law for each frequency range. The other is that the outer signal is inaccessible. The former problem is solved by introducing a weighing rational function. The latter problem is fortunately settled by the fact that disturbance and outer signal have a simple relation to each other.

A Comparison of Driver Steering Activity during Motion on an Even and Uneven Road Surface

SUMMARY The paper presents results of simulation investigation on driver-vehicle motion on an even and uneven road. The 14 degrees of freedom vehicle model has been verified experimentally on an even road surface. The driver models were adopted to perform typical motion cases: circular steady state and stright line. Road irregularities were realizations of a random process and they represented four road categories. The driver steering activity measure was adopted to investigate the influence of road undulations. The performed simulation investigations indicate that there is a considerable influence of road irregularities on the driver-vehicle system behaviour during two typical motion cases.

A Two-Dimensional Statistical Model of an Uneven Road Surface.

This paper describes a mathematical model of an uneven road surface where the statistical characteristics of the roughness are isotropic. A spectral density matrix is obtained in consideration of a correlation of the roughness between the right and the left tracks. By the spectral factorization of the rational spectral density matrix, which results from the approximation of the cross-spectral density function, the transfer function matrix is formulated, and the minimal realization of the shaping filter is obtained analytically. The results of the numerical simulation using the shaping filter are in good agreement with the analytical ones.

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

A two-dimensional statistical model of an uneven road surface.

This paper describes a mathematical model of an uneven road surface where the statistical characteristics of the roughness are isotropic. A spectral density matrix is obtained in consideration of a correlation of the roughness between the right and the left track. By factorization of the rational spectral density matrix, which results from the approximation of the cross spectral density, the transfer function matrix is formulated, and the minimal realization of the shaping filter is obtained analytically. The results of the numerical simulation using the shaping filter are in good agreement with analytical ones.

Optimal control of an active suspension for a wheeled robotic vehicle. Experiments on a one-wheel model.

Among robotic locomotion mechanisms, a wheel method is best suited for high speed locomotion and high energy efficiency, but it is restricted to even road surfaces. In this paper, an active suspension is applied to a wheeled robotic vehicle to suppress the vibration of the vehicle caused by the road's roughness. An experimental device composed of a vehicle simulator and a road simulator is manufactured. The vehicle simulator is a one-wheel model using a direct drive motor for a suspension actuator. The control method is based on the discrete optimal control theory and uses the data gained from the internal sensors. Experimental results show that the estimation of the state values by the internal sensor signals is effective and the high performance of the vehicle body stability is achieved by suspension control during the run on the uneven road surface.

A TWO-DIMENSIONAL MODEL OF THE INTERACTION BETWEEN A PNEUMATIC TIRE AND AN EVEN AND UNEVEN ROAD SURFACE

SUMMARY The paper presents a two-dimensional model of pneumatic tire interacting with even and uneven road surface. The model describes jointly radial and tangential tire properties, assuming variation of the friction coefficient at the contact points. Such a model can be useful in describing the interaction between the pneumatic tire and road, that is characterized by a relatively big value of the ratio of the road unevenness height to its length.

A NEW ANALYTICAL MODEL TO INVESTIGATE TRANSIENT ROLLING CONDITIONS OF A STEEL-BELTED TIRE

SUMMARY A general mechanical model has been developed for the analysis of rolling steel belted tires under transient speed and acceleration conditions. The belt circumference of the tire model is subdivided into an (externally) unloaded area and a loaded contact patch. The patch is subdivided into slip and non-slip zones. Two deformation fields describe bending and extensional strain of the steel belt. The tread deformations are governed separately by shear and pressure fields to be determined along the tire circumference. The model is applicable to both even and uneven road surfaces. The principle of virtual work is applied to obtain partial differential equations of motion for the belt and the tread. In addition, transient slip and non-slip conditions are provided for the contact patch area. A discretization in space and time, based upon finite differences and Newmark's integration method, is applied to solve the equations of motion along with the boundary and slip conditions. Preliminary computer resul...