Abstract: A time series waveform of detected vibration of a tire during travel is multiplied by a window function of a prescribed time width and a time series waveform for each time window is extracted to calculate a feature vector from the time series waveform for each time window. Thereafter, when determining the state of the road surface during travel using the feature vector for each time window and road surface models, a plurality of the aforementioned road surface models is constructed depending on the magnitude of a braking/driving force, the braking/driving force acting on the aforementioned tire is estimated, and the state of the road surface is determined using the road surface models, which depend on the aforementioned feature vector and the magnitude of the estimated braking/driving force.

Abstract: In a method for determining a road surface condition, the speed of calculation is improved by applying an appropriate path limitation. To further improve the accuracy of determination, a time-series waveform of tire vibration detected by an acceleration sensor is windowed at time width T by a windowing means, and time-series waveforms of tire vibration in the respective time windows are extracted before feature vectors Xi of the respective time windows are calculated. Then kernel functions KA (X, Y) are calculated from the feature vectors Xi for the respective time windows and road surface feature vectors Yi, which are feature vectors for the respective time windows calculated from time-series waveforms of tire vibration having been determined in advance for distinctive road surface conditions.

Abstract: The invention provides a road surface condition determining system with improved accuracy. In the system, a plurality of vehicles Wi are used, each equipped with on-board sensors (11, 12) for acquiring vehicular information, which is information on the behavior of the vehicle during travel, a feature value calculating means (13) for calculating a plurality of feature values to be used in estimating the condition of the road surface on which the vehicle is traveling from the vehicular information acquired by the on-board sensors (11, 12), and a transmitter 16 for transmitting the feature values to the outside of the vehicle. A server (20) has a data storage means (22) for accumulating the plurality of feature values from the plurality of vehicles. A road surface condition determining unit (30) determines a road surface condition using the accumulated feature values. And the system determines the road surface condition at the location within a predetermined range within a predetermined space of time.

Abstract: A tire contact state estimation method includes: an information acquisition step of acquiring information of the tire; a correlation strength calculation step of calculating a first correlation strength between the rotational velocity and the braking and driving force, and also calculating a second correlation strength between the slip angle and the generated lateral force; a change detection step of detecting whether the first correlation strength has increased or decreased by a first threshold or more with respect to a predetermined first reference value, and also detecting whether the second correlation strength has increased or decreased by a second threshold or more with respect to a predetermined second reference value; and an estimation step of estimating at least two of the following: a condition of a road surface in contact with the tire, a tire internal pressure state, and a tire abrasion state.

Abstract: In order to provide a method for accurately determining the road surface state even when the tire state and external information change, when determining the state of the road surface from the time-varying waveform of vibration of a tire during travel detected by a vibration detection means, in addition to the vibration waveform of the tire, tire state information and external information inputted to the tire are acquired, and a determination parameter for determining the road surface state calculated from the tire vibration waveform is corrected or modified on the basis of the acquired tire state information or external information, and either the road surface state is determined using said corrected or modified determination parameter, or the road surface state is determined from the determination parameter and the state information or external information.

Abstract: The invention provides an apparatus, program, and method for controlling the automatic spraying of an antifreezing agent that can reduce the cost of the antifreezing agent and the impact of salt damages caused by the antifreezing agent. This is accomplished by reducing the amount of antifreezing agent to be sprayed automatically according to road surface condition and reducing the amount of the antifreezing agent left unused on completion of the spray operation by grasping in advance the total spray amount of the antifreezing agent.

Abstract: In a method for determining a road surface condition, the speed of calculation is improved by applying an appropriate path limitation. To further improve the accuracy of determination, a time-series waveform of tire vibration detected by an acceleration sensor is windowed at time width T by a windowing means, and time-series waveforms of tire vibration in the respective time windows are extracted before feature vectors Xi of the respective time windows are calculated. Then kernel functions KA (X, Y) are calculated from the feature vectors Xi for the respective time windows and road surface feature vectors Yi, which are feature vectors for the respective time windows calculated from time-series waveforms of tire vibration having been determined in advance for distinctive road surface conditions.

Abstract: A method is provided for estimating a road surface condition by accurately determining whether or not there has been any large input to a tire without increasing the number of sensors. An acceleration sensor is disposed on the tire to detect the vibration of the tire in motion. The positions of leading end point and trailing end point of tire contact patch are estimated from the peak positions appearing in the time-variable waveform of the vibration. At the same time, the contact time, extra-contact time, and revolution time of the tire are calculated from the estimated positions of leading end point and trailing end point. Then using one or more of the calculated data, it is determined whether or not the estimated positions of leading end point and trailing end point are equal to the actual positions of leading end point and trailing end point. And if the result of the leading and trailing position determination is “incorrect estimation”, the estimation of a road surface condition is not performed.

Abstract: The invention provides a road surface condition determining system with improved accuracy. In the system, a plurality of vehicles Wi are used, each equipped with on-board sensors (11, 12) for acquiring vehicular information, which is information on the behavior of the vehicle during travel, a feature value calculating means (13) for calculating a plurality of feature values to be used in estimating the condition of the road surface on which the vehicle is traveling from the vehicular information acquired by the on-board sensors (11, 12), and a transmitter 16 for transmitting the feature values to the outside of the vehicle. A server (20) has a data storage means (22) for accumulating the plurality of feature values from the plurality of vehicles. A road surface condition determining unit (30) determines a road surface condition using the accumulated feature values. And the system determines the road surface condition at the location within a predetermined range within a predetermined space of time.

Abstract: The invention provides a method for accurately predicting a road surface condition at a location within a predetermined range. To that end, the road surface conditions at the location within the predetermined range are predicted using road surface estimation decision values calculated using vehicular information, which is the information on the behavior of a vehicle Wi during travel obtained by an on-board sensor mounted on the vehicle, or estimated road surface conditions estimated using the road surface estimation decision values. In doing so, the road surface condition at the location within the predetermined range is predicted based on the road surface estimation decision values calculated for the location within the predetermined range or the time-dependent changes in the estimated road surface conditions.

Abstract: A method is provided for estimating a road surface condition by accurately determining whether or not there has been any large input to a tire without increasing the number of sensors. An acceleration sensor is disposed on the tire to detect the vibration of the tire in motion. The positions of leading end point and trailing end point of tire contact patch are estimated from the peak positions appearing in the time-variable waveform of the vibration. At the same time, the contact time, extra-contact time, and revolution time of the tire are calculated from the estimated positions of leading end point and trailing end point. Then using one or more of the calculated data, it is determined whether or not the estimated positions of leading end point and trailing end point are equal to the actual positions of leading end point and trailing end point. And if the result of the leading and trailing position determination is “incorrect estimation”, the estimation of a road surface condition is not performed.

Abstract: The invention provides an apparatus, program, and method for controlling the automatic spraying of an antifreezing agent that can reduce the cost of the antifreezing agent and the impact of salt damages caused by the antifreezing agent. This is accomplished by reducing the amount of antifreezing agent to be sprayed automatically according to road surface condition and reducing the amount of the antifreezing agent left unused on completion of the spray operation by grasping in advance the total spray amount of the antifreezing agent.

Abstract: A time-series waveform of tire vibration detected by an acceleration sensor is windowed by a windowing unit, time-series waveforms of the tire vibration are extracted for respective time windows, and feature vectors of the respective time windows are calculated. Then kernel functions are calculated from the feature vectors of the respective time windows and road surface feature vectors, which are the feature vectors for the respective time windows calculated from the time-series waveform of the tire vibration obtained for distinctive road surface conditions calculated in advance. And the road surface condition is determined by comparing values of discriminant functions using the kernel functions. As a result, the road surface condition can be determined from the time-series waveform of the tire vibration without detecting peak positions or measuring the wheel speed. Moreover, robustness against changes in tire size can be added to the determination of the road surface condition.

Abstract: A tire contact state estimation method includes: an information acquisition step of acquiring information of the tire; a correlation strength calculation step of calculating a first correlation strength between the rotational velocity and the braking and driving force, and also calculating a second correlation strength between the slip angle and the generated lateral force; a change detection step of detecting whether the first correlation strength has increased or decreased by a first threshold or more with respect to a predetermined first reference value, and also detecting whether the second correlation strength has increased or decreased by a second threshold or more with respect to a predetermined second reference value; and an estimation step of estimating at least two of the following: a condition of a road surface in contact with the tire, a tire internal pressure state, and a tire abrasion state.

Abstract: A method capable of estimating a snowy road surface condition during vehicular travel in finer classification. In this method, tire vibrations in the circumferential direction, road surface temperature (T), and tire-generated sound are detected by an acceleration sensor, a road surface thermometer, and a microphone, respectively. Then band values P11, P12 and P13 for a pre-leading-edge region (R1), band values P21, P22 and P23 for a leading-edge region (R2), band values P31, P32 and P33 for a pre-trailing-edge region (R3), band values P41 and P42 for a trailing-edge region (R4), and band values P51, P52 and P53 for a post-trailing-edge region (R5) are calculated from the tire vibration data. A sound pressure level ratio (Q)=(PA/PB), which is the ratio of a band power value (PA) of a low frequency band to a band power value (PB) of a high frequency band, is calculated from data on the tire-generated sound.

Abstract: A time-series waveform of tire vibration detected by an acceleration sensor is windowed by a windowing means, time-series waveforms of the tire vibration are extracted for respective time windows, and feature vectors of the respective time windows are calculated. Then kernel functions are calculated from the feature vectors of the respective time windows and road surface feature vectors, which are the feature vectors for the respective time windows calculated from the time-series waveform of the tire vibration obtained for distinctive road surface conditions calculated in advance. And the road surface condition is determined by comparing values of discriminant functions using the kernel functions. As a result, the road surface condition can be determined from the time-series waveform of the tire vibration without detecting peak positions or measuring the wheel speed. Moreover, robustness against changes in tire size can be added to the determination of the road surface condition.

Abstract: The vibration of a tire 10 of a running vehicle in the circumferential direction or the width direction is detected by a road surface condition estimating tire 10, provided with an acceleration sensor 11 and a signal processing unit 12. Data of a detected vibration waveform are divided into data of three domains, namely, a pre-leading domain, a contact patch domain, and a post-trailing domain, and then the vibration levels in the pre-leading domain and the contact patch domain, respectively, are extracted. At the same time, a vibration component in a low-frequency band and a vibration component in a high-frequency band are extracted respectively from the vibration levels in the respective domains, and respective vibration level ratios R, which are each a ratio thereof, are calculated.

Abstract: A vehicle velocity detector 15 is provided, velocity V is detected from position data of the vehicle calculated by using signal from satellites, which is received by a GPS receiver 11 installed to a vehicle body, wheel rotation velocity Vw0 detected by a wheel velocity sensor 12 is corrected in accordance with tire inner pressure detected by a pressure sensor 13 so as to obtain wheel rotation velocity (correction value) Vw, velocity ratio R=(Vw/V), which is ratio of the corrected wheel rotation velocity Vw and the detected wheel velocity V, is calculated and tire wear amount is estimated in accordance with velocity ratio R so that tire wear amount can be measured precisely without processing the tire tread portion.

Abstract: A method capable of estimating a snowy road surface condition during vehicular travel in finer classification. In this method, tire vibrations in the circumferential direction, road surface temperature (T), and tire-generated sound are detected by an acceleration sensor, a road surface thermometer, and a microphone, respectively. Then band values P11, P12 and P13 for a pre-leading-edge region (R1), band values P21, P22 and P23 for a leading-edge region (R2), band values P31, P32 and P33 for a pre-trailing-edge region (R3), band values P41 and P42 for a trailing-edge region (R4), and band values P51, P52 and P53 for a post-trailing-edge region (R5) are calculated from the tire vibration data. A sound pressure level ratio (Q)=(PA/PB), which is the ratio of a band power value (PA) of a low frequency band to a band power value (PB) of a high frequency band, is calculated from data on the tire-generated sound.

Abstract: A method, featuring robustness against changes in tire size, is provided for determining a road surface condition by dividing a time-series waveform of tire vibrations into windows without resorting to detection of the peak positions or measurement of the wheel speed. A time-series waveform of tire vibrations detected by a tire vibration detecting unit is windowed by a windowing unit. Time-series waveforms are extracted from the respective time windows, feature vectors X are calculated therefor, and then likelihoods Z for road-surface HMMs (hidden Markov models) are calculated. The likelihoods Z1 to Z5 calculated for the respective road-surface HMMs are compared with one another, and a road surface condition corresponding to the road-surface HMM showing the highest likelihood is determined to be the condition of the road surface on which the tire is running.