JP5130181B2 - Wheel vibration extraction device and road surface state estimation device - Google Patents

Description

  The present invention relates to an apparatus for extracting wheel vibrations generated according to road surface conditions when a vehicle travels, and an apparatus for estimating road surface conditions based on the wheel vibrations.

  The propulsive force for running the vehicle, the braking force for stopping the vehicle, and the turning force are generated by frictional force between the wheels (tires) and the road surface, and the vehicle is caused to vibrate up and down due to the unevenness of the road surface. Thus, since the road surface state greatly affects the behavior of the vehicle, conventionally, the state of the traveling road surface is detected and used for vehicle control. The detection of the road surface state must be performed in the vehicle to be controlled. Therefore, the road surface state is detected or estimated from a change in the behavior of the vehicle during traveling.

  For example, Patent Document 1 is configured to detect vibration with a sensor attached to a tire or a wheel, detect the vibration by spectral analysis of the detected vibration, detect a vibration level, and estimate a road surface friction coefficient based on the detection result. The described apparatus is described. As a device for detecting a change in the behavior of a vehicle, Patent Document 2 captures sound with a sensor attached to an appropriate position of the vehicle body, and converts the captured signal into a signal for each sound source by independent component analysis (ICA). An apparatus is described that is configured to diagnose anomalies by separating and identifying the position of a sound source based on the separated signals.

JP 2003-182476 A JP 2006-208075 A

  A vehicle has various movable parts, and each of these parts becomes a vibration source or causes resonance. Therefore, the wheel not only vibrates according to the state of the road surface, but also vibrates with an excitation force transmitted from another movable part. Therefore, as described in Patent Document 1, the vibration detected by the sensor attached to the tire or the wheel includes various vibrations other than the vibration according to the road surface condition. In this case, analysis including vibrations caused by factors other than the road surface is performed, and the road surface state or its friction coefficient may not be accurately estimated. Further, in the configuration described in Patent Document 1, since the sensor rotates together with the tire, the configuration for receiving a signal from the sensor may be complicated, or the durability may be reduced. is there. In addition, a sensor must be provided for each tire, and the individual difference for each tire affects the detection accuracy, which may increase the estimation error of the road surface friction coefficient. Note that the device described in Patent Document 2 is for specifying the position of the sound source and cannot detect or estimate the road surface state.

  The present invention has been made by paying attention to the above technical problem, and can accurately detect the vibration of the wheels accompanying traveling, and accurately estimate the road surface state based on the detected signal. It is an object of the present invention to provide a wheel vibration extraction device and a road surface state estimation device that can perform the same.

  In order to achieve the above object, a first aspect of the present invention provides a wheel vibration extraction device that extracts vibrations generated on wheels of a vehicle according to a road surface on which the vehicle travels, and a plurality of the vibrations attached to the vehicle. Vibration detectors, vibration separating means for separating the observation signals obtained by these vibration detectors into a plurality according to the vibration source, and an observation signal based on the vibration of the wheel from the plurality of the separated observation signals And a wheel vibration specifying means for specifying.

  A second aspect of the present invention is a road surface state estimating device using the wheel vibration extraction device according to the first aspect, and estimates the state of the road surface based on the wheel vibration specified by the wheel vibration specifying means. A road surface condition estimating means is further provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the vibration separating means analyzes a plurality of observation signals detected by the plurality of vibration detectors and performs a plurality of correspondences with the vibration source. It is a wheel vibration extraction device or a road surface state estimation device characterized by including means for separating the observation signal.

  A fourth aspect of the present invention provides the wheel vibration extraction according to any one of the first to third aspects, wherein the plurality of vibration detectors are arranged under a spring in a suspension that supports a vehicle body of the vehicle. It is a device or a road surface state estimation device.

  A fifth aspect of the present invention provides the vehicle according to any one of the first to third aspects, wherein the vehicle includes a suspension system that connects the wheel and the vehicle body, and the plurality of vibration detectors are any of the suspension systems. The vibration of the wheel is determined from the vibration transmission characteristic of the suspension system that is attached to the component member and transmits the vibration of the wheel to the vibration detector and the observation signal based on the vibration of the wheel specified by the wheel vibration specifying means. The wheel vibration extraction device or the road surface state estimation device is further provided with a vibration calculation means for calculating.

  A sixth aspect of the present invention is the wheel according to any one of the first to fifth aspects, wherein the plurality of vibration detectors are attached to locations where vibrations of non-driving wheels of the vehicle are detected. It is a vibration extraction device or a road surface state estimation device.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the wheel vibration specifying means is preliminarily provided with road surface information including unevenness of the road surface, and is based on the vibration of the wheel based on the road surface information. A wheel vibration extraction device or a road surface state estimation device characterized by including means for specifying an observation signal.

  The invention according to claim 8 is the invention according to any one of claims 2 to 7, wherein the road surface state estimating means includes a reference frequency spectrum set in advance corresponding to the road surface state, and is specified by the wheel vibration specifying means. A road surface state estimating device comprising means for estimating a road surface state by comparing an observation signal based on the vibration of the wheel and the reference frequency spectrum.

  The invention according to claim 9 is the road surface state estimation according to claim 8, further comprising reference value correcting means for correcting the reference frequency spectrum based on information on the road surface including the unevenness of the road surface. Device.

  According to a tenth aspect of the present invention, in any one of the seventh to ninth aspects, the road surface information correcting means for correcting the information on the road surface provided in advance based on the road surface state estimated by the road surface state estimating means. The road surface state estimating apparatus further includes the road surface state estimating apparatus.

The invention of claim 11 is the invention of claim 2 of stone 10, and the detection of the vibration by the vibration detector when the vehicle is in a braking state, the separation of the observed signals by the vibration isolation means, said wheel vibration the specific observation signal based on the vibration of the wheel by a particular unit, the road surface condition further characterized by comprising road surface state inhibiting means for inhibiting at least one of the estimation of the state of the road surface by the estimation means It is an estimation device.

  According to the first aspect of the present invention, the observation signals obtained by the plurality of vibration detectors are separated, and the observation signals based on the wheel signals are obtained from the separated observation signals. The number of vibration detectors may be plural, but preferably, more than the number of vibration detectors such as wheels and power sources are used. Thus, since the observation signal based on the wheel vibration is separated from the observation signals obtained by the plurality of detectors, the wheel vibration can be accurately identified or detected.

  According to the invention of claim 2, since the road surface state is estimated based on the wheel vibration obtained as described above, the road surface state is accurately estimated due to the fact that the wheel vibration is accurately detected. It becomes possible to do.

  According to the invention of claim 3, since independent component analysis is performed for separating the observation signals obtained by the plurality of vibration detectors, the wheel vibration can be detected with higher accuracy, and the estimation accuracy of the road surface condition is improved. be able to.

  According to the fourth aspect of the present invention, vibration under suspension of the suspension is detected, so that wheel vibration can be detected with higher accuracy and road surface condition estimation accuracy can be improved.

  According to the invention of claim 5, even if the vibration of the wheel is attenuated or partially amplified by the suspension system, the characteristics of the suspension system that cause such vibration conversion are taken into consideration. Therefore, the vibration of the wheel obtained is close to the vibration detected directly from the wheel. That is, the vibration of the wheel can be obtained more accurately. In addition, the configuration for transmitting and receiving the detected signal is simplified, and inconveniences such as exchanging the vibration detector each time the wheel is replaced can be eliminated.

  According to the invention of claim 6, the vibration detector functions to detect the vibration of the non-driving wheel in the vehicle, and torque from the power source of the vehicle is not transmitted to the non-driving wheel. Therefore, vibration that better reflects the road surface condition can be detected, and the estimation accuracy of the road surface condition is improved.

  According to the invention of claim 7, since the wheel is vibrated by the unevenness of the road surface, by specifying the wheel vibration based on the road surface information including the unevenness, a specific error of the wheel vibration can be prevented in advance, or The specific accuracy of wheel vibration can be improved.

  According to the eighth aspect of the present invention, since the road surface state is estimated by comparing the reference frequency spectrum and the observation signal based on the vibration of the wheel corresponding to the road surface state, the estimation accuracy of the road surface state can be improved. .

  According to the ninth aspect of the present invention, since the road surface information can be obtained as so-called infrastructure information, the reference frequency spectrum is corrected using this information, so the so-called reference for estimating the road surface state is the road surface state. Accordingly, the estimation accuracy of the road surface condition can be improved.

  According to the invention of claim 10, when the road surface state is estimated, the road surface information serving as a reference for the estimation is corrected based on the estimation result, so that the so-called reference for estimating the road surface state is updated. Thus, the road surface state is better reflected, and as a result, the estimation accuracy of the road surface state can be improved.

  According to the invention of claim 11, when the braking force is acting on the wheel, the estimation of the road surface state is prohibited, so that the estimation of the road surface state incorporating the so-called disturbance accompanying the braking is not performed, and as a result It is possible to prevent or avoid erroneous estimation of the road surface condition.

  Next, the present invention will be described more specifically. The present invention is a device configured to detect a vibration of a wheel (tire) in a vehicle separately from other vibrations, and to estimate a road surface state based on the detected vibration. A four-wheeled automobile is most common, but is not limited to this, and may be a two-wheeled vehicle or a railway vehicle.

  A detector (sensor) for detecting the vibration is attached to an appropriate position of the vehicle body. The vibration detector may be a conventionally known one, and an acceleration sensor, a displacement sensor, a strain gauge, or the like can be used. In the device according to the present invention, the vibration detector is not attached to the wheel, but is attached to an appropriate position of the vehicle body. A plurality of vibration detectors are used. Preferably, the number of vibration sources or the number of vibration detectors greater than that is used. For example, when the suspension is a four-wheel independent suspension, it is preferable to provide two or more vibration detectors for one wheel in order to separate the input from the wheel and the input from the vehicle body. In addition, when the suspension is an axle suspension, it is preferable to provide three or more vibration detectors for one axle in order to separate the input from the left and right wheels and the input from the vehicle body. Furthermore, when a vibration generation source is provided in a suspension such as an in-wheel motor, it is preferable to increase the number of vibration detectors in accordance with the number of vibration generation sources.

  A preferred position for attaching these vibration detectors is a suspension, and in particular, an unsprung portion below a spring provided between the suspension and the vehicle body. Furthermore, because the vibration of the wheel affected by the road surface is detected, the main component of the vibration is the vibration from the wheel, and there is little vibration component from the engine and other appropriate resonance parts. It is preferable to attach a vibration detector.

  FIG. 3 shows an example in which a vibration detector is attached to a suspension system that supports a non-driving wheel of an automobile. The suspension shown here has a conventionally known configuration, and includes left and right wheel hubs 1 and 2. Are attached to the trailing arms 3 and 4, and the trailing arms 3 and 4 are attached to a vehicle body (not shown) so that a portion to which the wheel hubs 1 and 2 are attached rotates in the vertical direction. A shock absorber 5 is disposed between a portion of the trailing arms 3 and 4 close to the portion where the wheel hubs 1 and 2 are attached and the vehicle body, and an upper end portion of the shock absorber 5 is interposed via an upper support 6. It is connected to the car body. Further, a coil spring 7 is provided on the outer peripheral side of the shock absorber 5. The left and right trailing arms 3 and 4 are connected by an axle beam 8.

  An acceleration sensor 9, which is an example of a vibration detector, is provided at three locations of the trailing arms 3 and 4, a position close to the wheel hubs 1 and 2 and a center portion of the axle beam 8. This is because the three vibration sources are wheels (not shown), the engine that is the power source of the vehicle, and the suspension.

The vibration signal of the wheel is extracted (restored or separated) from the vibration (observation signal) detected by the three acceleration sensors 9 of No. 1 to No. 3, and the road surface state is estimated from the vibration signal of the wheel. The system is shown in FIG. Means (independent component analysis means) 10 for analyzing an independent component based on the vibration signal obtained by each acceleration sensor 9 is provided. Here, independent component analysis (ICA) is a signal analysis method for measuring overlapping data from a plurality of signal sources at multiple points, and separating and extracting the original signals. This is a conventionally known method as described in Japanese Patent Application Laid-Open No.-208075 and Japanese Patent Application Laid-Open No. 2007-270552. More specifically, in the independent component analysis, it is assumed that there is a relationship that can be expressed by equation (1) between the signal source s _j (t) and the observed signal x _j (t).

  Here, A is expressed by equation (2).

Therefore, an independent component can be extracted by estimating the A matrix from an observation signal in which a plurality of signals are mixed in an additive manner. Additional independent component analysis unit 10 is constructed by previously incorporating each vehicle, or obtained in advance based on the matrix A such as experimental or simulated for each wheel, this in the program to be executed by the micro-computer be able to. The independent component analyzing means 10 corresponds to the vibration separating means of the present invention.

  In the example shown in FIG. 1, it is assumed that there are three signal sources, and therefore three vibration signals (observation signals) are obtained by independent component analysis. Comparison means 11 is provided for comparing these vibration signals with a reference vibration signal. The comparison means 11 corresponds to the wheel vibration specifying means in the present invention, and is configured to perform comparison for specifying a wheel vibration signal (tire vibration signal) 12 from the separated vibration signal. ing. The reference vibration signal is vibration characteristic data (tire vibration characteristic data) 13 for each wheel, which is obtained in advance by experiments or the like, and the comparison means 11 reads or stores the tire vibration characteristic data in advance. The tire vibration characteristic data is compared with the vibration signal input from the independent component analyzing means 10 to identify the tire vibration signal. The identification method may be either a method of specifying by matching with the reference data, or a method of specifying the remaining one by excluding those that do not match.

  The configuration described above is a specific example of the wheel vibration extraction device according to the present invention, and the road surface state estimation device according to the present invention is configured to estimate the road surface state using the tire vibration signal 12 described above. Yes. First, frequency analysis means 14 for analyzing the separated and specified tire vibration signal 12 is provided. The frequency analysis means 14 is, for example, a fast Fourier transform (FFT) unit or an arithmetic unit that performs a fast Fourier transform (FFT), and more specifically, configured to analyze a frequency spectrum of a tire vibration signal. .

  The above tire vibration signal is not obtained by directly detecting the vibration of the wheel, but is extracted from the observation signal detected through the suspension, so it is influenced by the vibration characteristics of the suspension. Yes. For example, the vibration of a specific frequency is attenuated, or the vibration level of the specific frequency is increased due to the resonance of the suspension. Therefore, the vibration caused by the so-called disturbance factor is corrected. An example of the correction is to correct the frequency spectrum of the tire vibration signal by the frequency spectrum ratio 15 between the wheel and the suspension. In the example shown in FIG. 1, the correction means 16 for performing such correction is provided.

  The frequency spectrum ratio 15 between the wheel and the suspension is a ratio between the frequency spectrum of the vibration applied to the wheel and the frequency spectrum of the vibration detected by the suspension due to the vibration. Or can be obtained by measurement in advance using a model equivalent thereto. The correction means 16 is configured to correct the frequency spectrum of the tire vibration signal by the frequency spectrum ratio 15. For example, the correction means 16 multiplies or divides the frequency spectrum of the tire vibration signal by a frequency spectrum ratio 15 prepared in advance to remove or reduce the influence of the vibration transmission path such as the suspension. It is configured to determine a signal. Therefore, the correcting means 16 corresponds to the vibration calculating means of the present invention.

  Furthermore, road surface state estimation means 17 is provided. The road surface state estimating means 17 is configured to estimate a road surface state (for example, an uneven state) that causes the vibration based on a predetermined vibration signal. For example, since the road surface state and the vibration generated on the wheels are related to each other, it is possible to map the road surface state and the wheel vibrations. In addition, since the vibration which arises in a wheel changes with elastic coefficients, damping characteristics, etc. of a tire, said map will be provided for every wheel. Further, since the vibration generated in the wheel varies depending on the vehicle speed or the rotation speed of the wheel, the above map may be a three-dimensional map using the vehicle speed as a parameter. The road surface state estimation means 17 uses such a map and the tire vibration signal corrected by the correction means 16 to obtain a road surface state corresponding to the tire vibration signal from the map.

  The operation of the system having the configuration shown in FIG. 1, that is, the control of the wheel vibration extraction and the road surface state estimation by the apparatus according to the present invention will be described below. FIG. 2 is a flowchart for explaining the control example. First, a vibration signal is detected by each acceleration sensor 9 (step S1). Independent component analysis is performed on the plurality of vibration signals (step S2), and the plurality of vibration signals are separated and extracted. The independent component analysis is as described above.

  FIG. 4 shows an example of a signal input to a vehicle wheel equipped with the suspension shown in FIG. 3 described above, a signal detected by the acceleration sensor 9, and a signal extracted and separated by independent component analysis. ing. The vehicle engine (not shown) mounted on the test bench is operated, and the wheel selected as the measurement target in that state or the place where the wheel is mounted is hit, and the like (a) of FIG. 4 is detected by the three acceleration sensors 9 respectively. These detection signals include signals corresponding to vibrations from the wheels, vibrations from the engine, and vibrations due to suspension or vehicle body resonance. When independent component analysis is performed on these three vibration signals, the three signals shown in FIG. 4C are separated and extracted.

  A tire vibration signal is specified from the plurality of separated / extracted vibration signals (step S3). This is a control executed by the comparison means 11 described above, and the tire vibration signal is specified by comparing the reference tire vibration characteristic data with the plurality of vibration signals. This may be performed by using a tire vibration signal that matches the reference data, or by sequentially removing non-matching vibration signals and using the remaining vibration signals as tire vibration signals. .

  Frequency analysis is performed on the tire vibration signal specified in this way (step S4). This is the control performed by the frequency analysis means 14 described above, and the frequency spectrum analysis is performed on the tire vibration signal specified in step S3 by FFT or the like. Since the frequency spectrum obtained in this way is influenced by the suspension, the tire vibration signal is calculated by correcting the frequency spectrum by the above-described frequency spectrum ratio (step S5). The correction or calculation is as described above, and the road surface condition is estimated based on the tire vibration signal thus obtained (step S6). The road surface state can be estimated using a map prepared in advance as described above.

  Therefore, according to the wheel vibration extraction device according to the present invention, it is possible to accurately extract or restore the vibration of the wheel using a plurality of observation signals. In particular, tire vibration can be obtained more accurately by performing the extraction, separation or restoration by an independent component analysis technique. In addition, the vibration signal of the wheel can be obtained accurately by detecting the vibration of multiple places other than the wheel (particularly the unsprung part) without attaching the vibration detector to the wheel. The configuration of the system can be simplified, and the durability can be improved. In addition, troublesome tire replacement can be avoided. And it becomes possible to improve the control precision of various controls, such as estimation of the road surface state which uses the wheel vibration, and control of the vibration damping characteristic of the suspension.

  On the other hand, according to the road surface state estimation device according to the present invention, the road surface state is estimated based on the tire vibration signal specified as described above or the vibration signal obtained by correcting the tire vibration signal, so that the road surface state is reflected more accurately. The road surface state is estimated using the vibration signal thus obtained, and the estimation accuracy of the road surface state can be improved.

Further, the acceleration sensor 9 may also be configured to detect any vibration of the wheel and non-driven wheel and the drive wheel, preferably of the suspension (Tokuniso to detect the vibration of the non-driven wheels Attach to the unsprung part. If comprised in this way, the influence at the time of a wheel slipping by driving force can be excluded. In addition, transmission of vibrations from the drive system can be eliminated, and accordingly, the number of vibration input sources is reduced, and the number of vibration detectors required for applying independent component analysis is reduced. Can do. After all, by configuring to detect the vibration of the non-driven wheels, it is possible to reduce the number of vibration detectors and reduce the cost, and to improve the estimation accuracy of the road surface condition become.

  In addition, when it is necessary to detect the vibration of the driving wheel, the road surface state is estimated when the driving force or the accelerator opening (or the required driving amount) is equal to or less than a predetermined threshold value. With such a configuration, the road surface state is estimated in a state where the influence of the driving force on the wheel whose vibration is to be detected is as small as possible, so that erroneous estimation can be prevented or the estimation error can be reduced. . Further, it is possible to prevent or suppress an increase in the number of vibration detectors.

  By the way, as for the input to the wheel, not only the vibration from the road surface and the driving force from the engine, but also the braking force is inputted when the brake is operated. Since the braking force affects the behavior of the wheel, it acts as a disturbance when detecting the road surface state based on the vibration of the wheel. Since it is difficult to accurately remove only such disturbances, it is preferable to prohibit estimation of road surface conditions during braking in order to avoid erroneous determination of road surface conditions.

  FIG. 5 is a block diagram showing an example of a system configured to perform such prohibition control. Note that the example shown in FIG. 5 is obtained by changing a part of the configuration shown in FIG. 1 described above. Therefore, the same parts as those shown in FIG. The description is omitted.

  In FIG. 5, the detection means 18 which detects a braking state is provided. The detection means 18 is a means for detecting a braking state by using a signal of a brake switch (not shown) which is turned on when a brake pedal provided in the vehicle is depressed, or based on brake hydraulic pressure. And means for detecting the braking state. When a braking state is detected, a prohibition signal is output from the detection means 18 to the road surface state estimation means 17 so that the estimation of the road surface state is prohibited. In the configuration shown in FIG. 5, the correction unit 16 described above is not provided, and the road surface state is estimated based on the frequency spectrum analyzed by the frequency analysis unit 14.

  FIG. 6 is a flowchart for explaining an example of the road surface state prohibition control in the system shown in FIG. 5, and the example shown here is a partial modification of the example shown in FIG. Therefore, the same steps as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. In FIG. 6, the detection of the braking state is executed in parallel with or after the frequency analysis of the tire vibration signal (step S4) (step S41). Specifically, this is reading of a signal that changes due to a braking operation, such as a brake switch signal or brake hydraulic pressure. Based on the read signal, it is determined whether or not the vehicle is in a braking state (step S42).

When it is determined negative in step S42 because it is not in the braking state, the process proceeds to step S6, and the road surface state is estimated by comparing the frequency spectra. On the other hand, if a positive determination is made in step S42, that is, if it is detected that the vehicle is in a braking state, step S6 is skipped and the process returns without performing any particular control. Accordingly, since the estimation of the road surface state is not executed in the braking state, the estimation of the road surface state based on the tire vibration signal in a state where there is a disturbance can be avoided, and the erroneous estimation of the road surface state can be prevented.

  As described above, the apparatus according to the present invention uses tire vibration characteristic data (corresponding to the reference vibration spectrum in the present invention) serving as a reference for specifying the tire vibration signal. Since the tire vibration characteristic data needs to be data on the road surface for each point where the vehicle travels, data at the current time of the vehicle is used when the vehicle travels. For this purpose, it is preferable to store road information including road surface unevenness and frequency characteristic data corresponding to the unevenness in a navigation system that can detect and output the current position of the vehicle together with map information around the vehicle. Then, in accordance with the detection of the current position of the vehicle, the frequency characteristic data for the current position is read out, and compared with the plurality of vibration signals described above, the tire vibration signal is specified.

  FIG. 7 is a block diagram showing an example of a system configured to perform such control. Note that the example shown in FIG. 7 is obtained by changing a part of the configuration shown in FIG. 1 described above. Therefore, the same parts as those shown in FIG. The description is omitted.

  In FIG. 7, the navigation system 19 includes a traveling point detection unit 20 that detects the position (traveling point) of the host vehicle as position data on map information, and is based on a signal from a GPS (global positioning system) or a sign post. When the traveling point of the host vehicle is detected, road surface unevenness information 21 about the traveling point is read. The road surface unevenness information 21 includes not only information indicating the actual degree of unevenness on the road surface, but also frequency spectrum information of vibration caused by the unevenness.

  The comparison means 11 is configured to read the frequency spectrum information as reference data and compare the reference data with vibration signals separated and extracted by independent component analysis. In the configuration shown in FIG. 7, the above-described correction unit 16 is not provided, and the road surface state is estimated based on the frequency spectrum analyzed by the frequency analysis unit 14.

  FIG. 8 is a flowchart for explaining a control example of vibration extraction and road surface state estimation by the system shown in FIG. 7, and the example shown here is a partial modification of the example shown in FIG. . Therefore, the same steps as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. In FIG. 8, in parallel with or after the independent component analysis in step S2, the driving point is detected by the navigation system 19 (step S21), and road surface unevenness information about the detected driving point is acquired. (Step S22). In the subsequent step S3, the tire vibration signal is specified based on the road surface unevenness information acquired in relation to the travel point. In the control example shown in FIG. 8, correction of the tire vibration frequency spectrum is not performed, and after analyzing the frequency of the tire vibration signal, the road surface condition is estimated using the analyzed tire vibration frequency spectrum. (Step S6).

  Therefore, by configuring as shown in FIGS. 7 and 8, the reference data used for specifying the vibration signal accurately reflects the actual road surface, so that the accuracy of specifying the vibration signal is improved. As a result, the estimation accuracy of the road surface condition can be improved.

  Note that data serving as a reference for specifying the tire vibration signal can be acquired and stored as the vehicle travels. For example, an unevenness detector such as a camera or radar is mounted on the vehicle, and the obtained road surface unevenness information and tire vibration feature data corresponding to the road surface unevenness information are stored in correspondence with the positions on the map. In this way, the reference data can be automatically acquired, and the data obtained by actually traveling can be obtained to better reflect the actual road surface condition. Can do.

  The road surface unevenness information can be obtained by inspecting the road surface with a camera, a radar, or the like when actually traveling, and can be acquired from the outside via a navigation system or the like. That is, the road surface unevenness information can be updated sequentially, and it is preferable to use the updated information for specifying the tire vibration signal and estimating the road surface state.

  FIG. 9 is a block diagram illustrating an example of an apparatus configured to effectively use acquired or updated road surface information. Note that the example shown in FIG. 9 is obtained by changing a part of the configuration shown in FIG. 1 described above. Therefore, the same parts as those shown in FIG. The description is omitted.

  In FIG. 9, detection means 22 for detecting road surface unevenness information is provided. This detection means 22 obtains the road surface shape with a camera or radar mounted on the vehicle, obtains unevenness information from the data, and further sets a reference frequency spectrum according to the unevenness information, or by a navigation system. A configuration for acquiring road surface unevenness information and a reference frequency spectrum corresponding to the information is provided. Such road surface unevenness information and the corresponding reference frequency spectrum are acquired sequentially, not only when traveling, so the road surface unevenness information and reference frequency spectrum of a predetermined travel point may be different from the conventional ones. In this case, the road surface unevenness information and the reference frequency spectrum are updated.

  The comparison means 11 is configured to identify the tire vibration signal by comparing the data acquired or updated in this way with a plurality of vibration signals separated and extracted by the independent component analysis. Therefore, even if the unevenness of the road surface changes due to construction or deterioration over time, the reference data for identifying the vibration signal is always the latest, so erroneous vibration from multiple vibration signals Specifying the signal as a tire vibration signal can be prevented or suppressed.

  On the other hand, reference correction means 23 for correcting the reference vibration spectrum for estimating the road surface state based on the acquired or updated road surface unevenness information is provided. This is a means for correcting a vibration spectrum in a map in which road surface conditions such as a road surface friction coefficient are set corresponding to the vibration spectrum, and corresponds to the reference value correction means in the present invention. For example, it is possible to obtain the difference between the frequency spectrum of the road surface unevenness at the travel point and the vibration spectrum of the road surface unevenness actually obtained by traveling and add the difference to the reference frequency spectrum. In this case, since the vibration spectrum changes according to the vehicle speed, the correction is performed in consideration of the difference in the vibration spectrum depending on the vehicle speed. The road surface state estimation means 17 is configured to estimate the road surface state using the reference vibration spectrum corrected as described above.

  FIG. 10 is a flowchart for explaining road surface state estimation control performed by the system shown in FIG. 9, and the example shown here is a partial modification of the example shown in FIG. Therefore, the same steps as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. 2 and the description thereof is omitted. In FIG. 10, road surface unevenness information of the travel point is acquired (read) in parallel with or subsequent to the independent component analysis in step S <b> 2. This is control by the detection means 22 mentioned above, and a tire vibration signal is specified using the road surface unevenness | corrugation information of the driving | running | working point (step S3).

  On the other hand, the reference vibration spectrum for estimating the road surface condition is corrected in parallel with or after the frequency analysis of the tire vibration signal in step S4 (step S43). This control is a correction executed by the reference correction means 23 described above, and the reference vibration spectrum is corrected based on the newly obtained road surface unevenness information. Thereafter, the road surface condition is estimated by comparing the corrected reference vibration spectrum with the frequency spectrum of the tire vibration signal (step S6).

  Therefore, by configuring as shown in FIG. 9 and FIG. 10, the road surface state is estimated with the latest reference vibration spectrum, so that it is possible to accurately estimate the road surface state, or erroneous estimation is performed. It can be prevented or suppressed.

  By the way, although the road surface unevenness state changes due to repair work or deterioration, etc., when the reference vibration spectrum for estimating the road surface state is regularly updated, the actual road surface unevenness state There are cases where the reference vibration spectrum does not match. When the road surface unevenness information is obtained by actually traveling, the difference between the actual road surface unevenness state and the reference vibration spectrum can be prevented or suppressed by updating the reference vibration spectrum. In that case, it is confirmed that the road surface unevenness information obtained by traveling reflects the actual road surface unevenness state.

  FIG. 11 shows an example of a system configured to correct (or update) road surface unevenness information as described above. Note that the example shown in FIG. 11 is obtained by changing a part of the configuration shown in FIG. 1 described above. Therefore, the same parts as those shown in FIG. The description is omitted.

  In FIG. 11, a navigation system 19 is provided. The navigation system 19 includes a travel point detection unit 20 that detects the current travel point of the host vehicle, and reads road surface unevenness information 21 about the detected travel point. It is configured as follows. This is the same as the configuration in the system shown in FIG.

  Furthermore, road surface unevenness information correcting means 24 for correcting road surface unevenness information by the navigation system 19 is provided. This corresponds to the road surface information correcting means in the present invention, and is used for estimating the road surface state when the road surface unevenness information set by the navigation system 19 is different from the road surface unevenness information obtained by actually traveling. The road surface unevenness information for determining the reference vibration spectrum is corrected with information obtained by actually traveling. For example, the road surface unevenness information is represented by a frequency spectrum, and if there is a difference between the frequency spectrum of the road surface unevenness information set by the navigation system 19 and the frequency spectrum obtained by the frequency analysis means 14, The navigation system 19 is configured to correct the frequency spectrum of road surface unevenness information.

  Such a difference in road surface unevenness information may occur due to a temporary factor. For example, the road surface may have changed due to snow, rain, or freezing, and the road surface state may have changed due to falling objects or temporary road surface repair work. Such a change in the road surface state is temporary, and it is highly likely that the road surface state has returned to the original state when the vehicle is next traveled. Therefore, the road surface unevenness information set by the navigation system 19 is The need for correction is low. Therefore, the presence or absence of a temporary factor is detected, and execution / non-execution of correction of road surface unevenness information is determined based on the detection result.

  In the system shown in FIG. 11, weather information detection means 25 is provided as a temporary factor detection means. This meteorological information detection means 25 is used for traveling at or near a travel point based on information sent via an artificial satellite, information sent from a base station via a sign post, or information sent via inter-vehicle communication. It detects the rain or snowfall on the planned road, its time, temperature, etc., determines whether there is a situation that changes the road surface condition, and outputs the determination result to the road surface unevenness information correcting means 24 It is configured.

  Further, reference correction means 23 for correcting the reference vibration spectrum for estimating the road surface condition is provided. The reference correction means 23 corrects the frequency spectrum that is a reference for estimating the road surface state as compared with the vibration spectrum obtained by the frequency analysis means 14, that is, the frequency spectrum of the tire vibration signal, as necessary, and the reference frequency. The spectrum is output to the road surface state estimating means 17 and the correction is performed based on the road surface unevenness information obtained from the road surface unevenness information correcting means 24. In other words, the reference correction unit 23 is configured in substantially the same manner as the reference correction unit 23 shown in FIG. 9 described above.

  FIG. 12 is a flowchart for explaining road surface state estimation control performed by the system shown in FIG. 11, and the example shown here is a partial modification of the example shown in FIG. Therefore, the same steps as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. In FIG. 12, the current traveling point of the host vehicle is detected by the navigation system 19 in parallel with or after the frequency analysis of the tire vibration signal in step S4 (step S401). Further, road surface unevenness information of the detected travel point is acquired (step S402). This is information stored in advance in the navigation system 19 or information sent from a base station or the like.

On the other hand, weather information is acquired in tandem with the control as described above (step S403). The control is executed by the weather information detecting means 25 described above, and the contents thereof are as described above. Next, it is determined whether or not the road surface is dry based on the acquired weather information (step S404). If an affirmative judgment at step S404, since the factors that temporarily changes the road surface condition, such as rainfall or snowfall is that does not occur, into the control for the correction of the road surface unevenness information.

  That is, it is determined whether or not the frequency spectrum of tire vibration obtained through the above-described independent component analysis has the same frequency component as the road surface unevenness information (step S405). If a negative determination is made in this step S405, there will be a discrepancy between the road surface unevenness information already set and the unevenness information detected for the actual road surface. Therefore, in this case, the navigation system 19 or the like The road surface unevenness information acquired by the above is corrected (step S406). A typical example of the correction is correction that is replaced with road surface unevenness information obtained by actually traveling.

  The reference vibration spectrum is corrected based on the road surface unevenness information thus obtained (step S407). This is the control executed by the reference correction means 23 shown in FIG. 11, and the contents thereof are as described above. Next, the control of step S6 described above, that is, the estimation of the road surface state based on the corrected reference vibration spectrum is performed.

  On the other hand, if the determination in step S405 is affirmative, the road surface unevenness information that has already been set and the road surface unevenness information obtained by actually traveling are not particularly inconsistent, and the process immediately proceeds to step S407. In this case, even if the reference vibration spectrum is corrected based on the road surface unevenness information, the original road surface unevenness information is not changed from before, so that the correction is not substantially performed.

  Further, when a negative determination is made in step S404 described above, correction of road surface unevenness information is prohibited. That is, if the determination is negative in step S404 because the road surface is wet due to rain or there is a temporary road surface state change factor such as snow or freezing, the process immediately proceeds to step S407. In this case as well, since the road surface unevenness information that is the basis thereof is not changed from before, no correction is performed. Therefore, the functional means for prohibiting correction of road surface unevenness information when a negative determination is made in step S404 corresponds to the prohibition means in the present invention.

  Therefore, by configuring as shown in FIGS. 11 and 12, the road surface state is estimated with the reference vibration spectrum being the latest, so that it is possible to accurately estimate the road surface state, and the reference vibration Even if the spectrum is corrected, it is not corrected depending on a change in the road surface condition due to temporary factors such as rainfall, so that erroneous estimation can be prevented or suppressed.

  The separation of the vibration signal (observation signal) in the present invention is preferably performed by the above-described independent component analysis. However, the separation is not limited to the independent component analysis as long as it can be separated into observation signals for each signal source. Further, the road surface state estimated in the present invention is mainly the road surface friction coefficient, but is not limited to this. Furthermore, in the example shown in FIG. 1 and FIG. 2 described above, the frequency analysis means 14 is provided without the correction means 16 for correcting the frequency spectrum of the tire vibration signal by the frequency spectrum ratio 15 between the wheel and the suspension. You may comprise so that a road surface state may be estimated immediately based on the calculated | required tire vibration spectrum.

It is a block diagram which shows an example of the apparatus which concerns on this invention by a functional means. 3 is a flowchart for explaining a control example of vibration signal extraction and road surface state estimation by the apparatus shown in FIG. 1. It is a figure for demonstrating the attachment position of a vibration detector. It is a diagram which shows an example of an input signal, a detection signal, and the isolate | separated signal, respectively. It is a block diagram which shows the other example of the apparatus based on this invention by a functional means. 6 is a flowchart for explaining a control example of vibration signal extraction and road surface state estimation by the apparatus shown in FIG. 5. It is a block diagram which shows the other example of the apparatus based on this invention by a functional means. It is a flowchart for demonstrating the control example of extraction of the vibration signal by the apparatus shown in FIG. 7, and estimation of a road surface state. It is a block diagram which shows the further another example of the apparatus based on this invention by a functional means. 10 is a flowchart for explaining a control example of vibration signal extraction and road surface state estimation by the apparatus shown in FIG. 9. It is a block diagram which shows the further another example of the apparatus based on this invention by a functional means. 12 is a flowchart for explaining a control example of vibration signal extraction and road surface state estimation by the apparatus shown in FIG. 11.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Wheel hub, 3, 4 ... Trailing arm, 5 ... Shock absorber, 7 ... Coil spring, 8 ... Axle beam, 9 ... Acceleration sensor, 10 ... Independent component analysis means, 11 ... Comparison means, 12 ... Tire Vibration signal, 13 ... Tire vibration characteristic data, 14 ... Frequency analysis means, 15 ... Frequency spectrum ratio, 16 ... Correction means, 17 ... Road surface state estimation means, 18 ... Detection means, 19 ... Navigation system, 20 ... Traveling point detection section 21 ... Road surface unevenness information, 22 ... Detection means, 23 ... Reference correction means, 24 ... Road surface unevenness information correction means, 25 ... Weather information detection means.

Claims (11)

In a wheel vibration extraction device that extracts vibration generated in the wheel of the vehicle according to the state of the road surface on which the vehicle travels,
A plurality of vibration detectors attached to the vehicle;
Vibration separating means for separating the observation signals obtained by those vibration detectors into a plurality according to the vibration source;
A wheel vibration extraction device comprising wheel vibration specifying means for specifying an observation signal based on wheel vibration from the plurality of observation signals separated into a plurality.   The road surface using the wheel vibration extraction device according to claim 1, further comprising a road surface state estimating unit that estimates a state of the road surface based on the wheel vibration specified by the wheel vibration specifying unit. State estimation device.   The vibration separating means includes means for analyzing a plurality of observation signals detected by the plurality of vibration detectors and separating them into a plurality of observation signals corresponding to the vibration source. The wheel vibration extraction device according to claim 1 or the road surface state estimation device according to claim 2.   The wheel vibration extraction device according to any one of claims 1 to 3, wherein the plurality of vibration detectors are arranged under a spring in a suspension that supports a vehicle body of the vehicle. The road surface state estimation apparatus described. The vehicle includes a suspension system that connects the wheel and the vehicle body,
The plurality of vibration detectors are attached to any component of the suspension system,
Vibration calculating means for calculating the vibration of the wheel from vibration transmission characteristics of the suspension system for transmitting the vibration of the wheel to the vibration detector and an observation signal based on the vibration of the wheel specified by the wheel vibration specifying means; The wheel vibration extraction device according to any one of claims 1 to 3, or the road surface state estimation device according to any one of claims 2 to 3, further comprising:   The wheel vibration extractor according to any one of claims 1 to 5, wherein the plurality of vibration detectors are attached to a location where vibrations of non-driving wheels of the vehicle are detected. The road surface state estimation device according to any one of claims 5 to 5.   7. The wheel vibration specifying means includes means for preliminarily including road surface information including road surface irregularities, and specifying an observation signal based on the wheel vibration based on the road surface information. 7. The wheel vibration extraction device according to claim 1 or the road surface state estimation device according to any one of claims 2 to 6.   The road surface state estimating means includes a reference frequency spectrum set in advance corresponding to the road surface state, and compares the observation signal based on the vibration of the wheel specified by the wheel vibration specifying means with the reference frequency spectrum to determine the road surface. The road surface state estimation device according to any one of claims 2 to 7, further comprising means for estimating a state.   The road surface state estimation device according to claim 8, further comprising reference value correction means for correcting the reference frequency spectrum based on road surface information including unevenness of the road surface.   10. The road surface information correcting means for correcting the information of the road surface prepared in advance based on the road surface state estimated by the road surface state estimating means. Road surface state estimation device. Detection of vibration by a vibration detector when the vehicle is in a braking state, separation of the observation signal by the vibration separation means, identification of an observation signal based on vibration of the wheel by the wheel vibration identification means, and the road surface road surface condition estimating apparatus according to any one of 請 Motomeko 2 to you, characterized in that it further comprises a prohibiting means for prohibiting at least one of the state estimator by estimating a state of the road surface 10.

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