JP2021135702A - ROAD SURFACE μ ESTIMATING DEVICE - Google Patents

Abstract

To provide a road surface μ estimating device capable of estimating a road surface μ at each point on a course of a vehicle before arrival.SOLUTION: In a vehicle 2, while an other vehicle estimation point closest to a vehicle 2 in a traveling direction is set as a first other vehicle estimation point P1, when a center of the first other vehicle estimation point P1 falls within a predetermined range in the traveling direction from the vehicle 2, that is, within a range of a distance B, a road surface μ from a traveling point P of the vehicle 2 to the first other vehicle estimation point P1 is estimated based on a road surface μ of the traveling point P of the vehicle and a road surface μ of the first other vehicle estimation point P1. At this time, it is estimated that the road surface μ between the points P-P1 linearly changes from a road surface μ=μ0 at the traveling point P to a road surface μ=μ1 at the first other vehicle estimation point P1; and as this road surface is closer to the first other vehicle estimation point P1, this road surface becomes a value close to the road surface μ=μ1 at the first other vehicle estimation point P1.SELECTED DRAWING: Figure 3

Description

The present invention relates to an apparatus for estimating a road surface μ (road surface friction coefficient).

Conventionally, an active torque split 4WD system is widely known as a 4WD (four-wheel-drive) system for a vehicle such as a four-wheel vehicle. In an example of the active torque split 4WD system, torque for traveling the vehicle is normally transmitted to the main drive wheels (for example, the left and right front wheels). When tire slip occurs while the vehicle is running, the μ (coefficient of friction) of the road surface during running is estimated, and the torque is generated by the electronically controlled coupling so that the tire slip is eliminated from the estimated road surface μ and the like. It is actively distributed to the main drive wheels and the sub drive wheels.

The road surface μ is estimated from the detection value of the wheel speed sensor that detects the wheel speed (rotational speed) of each wheel. Therefore, in the vehicle, it is not possible to estimate the road surface μ at the point where it has not arrived, and before arriving at the point on the course, the torque is distributed to the main drive wheels and the auxiliary drive wheels on the road surface at the point before arrival. It cannot be changed to the allocation according to μ.

As a technique for avoiding the occurrence of tire slip, for example, the probe center acquires slip history as probe information from each vehicle (probe car) traveling on the road, and obtains information on slip points where tire slip may occur. A system for delivering to each vehicle from the probe center has been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-10461

However, in a vehicle that has received information about a slip point, even if the road surface μ at the slip point can be estimated, the road surface μ at a point other than the slip point on the vehicle's path cannot be estimated before arrival.

An object of the present invention is to provide a road surface μ estimation device capable of estimating the road surface μ at each point on the course of a vehicle before arrival.

In order to achieve the above object, the road surface μ estimation device according to the present invention is a road surface μ estimation device mounted on a vehicle, and other vehicle estimation μ information relating to the road surface μ estimated by another vehicle and the road surface μ thereof. The information receiving means receives the information receiving means for receiving the other vehicle estimated point information related to the estimated point and the road surface μ of the other vehicle estimated point specified from the other vehicle estimated point information received by the information receiving means. According to the first estimation means for estimating based on the other vehicle estimation μ information and the first other vehicle estimation point, which is one other vehicle estimation point, within a predetermined range in the traveling direction from the vehicle due to the traveling of the vehicle. , The road surface μ between the vehicle's traveling point and the first other vehicle estimation point is changed from the road surface μ of the traveling point to the road surface μ of the first other vehicle estimation point estimated by the first estimation means, and It includes a second estimation means that estimates that the position closer to the first other vehicle estimation point has a value closer to the road surface μ of the first other vehicle estimation point.

According to this configuration, based on the road surface μ estimated by another vehicle and the point where the road surface μ is estimated, the road surface μ at each point on the vehicle's course is estimated before the vehicle arrives at that point. Can be done.

That is, in other vehicles, the road surface μ is estimated while traveling. The road surface μ estimation device mounted on the vehicle can receive the other vehicle estimation μ information related to the road surface μ estimated by the other vehicle and the other vehicle estimation point information related to the point where the road surface μ is estimated. When the estimated μ information and the other vehicle estimated point information are received, the road surface μ of the other vehicle estimated point specified from the other vehicle estimated point information is estimated based on the other vehicle estimated μ information. When the estimated point of the other vehicle closest to the vehicle in the direction of travel is set as the first estimated point of the other vehicle and the estimated point of the first other vehicle enters the predetermined range in the direction of travel from the vehicle, the road surface μ of the vehicle's traveling point and the first Based on the road surface μ of the other vehicle estimation point, the road surface μ from the vehicle traveling point to the first other vehicle estimation point is estimated. At this time, the road surface μ between these points changes from the road surface μ of the traveling point to the road surface μ of the first other vehicle estimation point, and the closer to the first other vehicle estimation point, the more the first other vehicle estimation point. It is estimated that the value is close to the road surface μ.

Therefore, the road surface μ at each point on the course of the vehicle can be estimated before arriving at that point.

The road surface μ estimation device estimates the first other vehicle according to the fact that the second other vehicle estimation point, which is another vehicle estimation point different from the first other vehicle estimation point, is within a predetermined range in the traveling direction from the vehicle. The road surface μ between the point and the second other vehicle estimation point is changed from the road surface μ of the first other vehicle estimation point to the road surface μ of the second other vehicle estimation point estimated by the first estimation means, and the first (2) The configuration may further include a third estimation means that estimates the position closer to the other vehicle estimation point so that the value is closer to the road surface μ of the second other vehicle estimation point.

With this configuration, the road surface μ from the first estimated position point of the other vehicle to the second estimated point of the other vehicle can be further estimated.

When a plurality of other vehicle estimation points are included in a small range smaller than a predetermined range, the first estimation means selects the other vehicle estimation point having the lowest road surface μ among the plurality of other vehicle estimation points as the first target point. The second target point is the other vehicle estimation point where the road surface μ is most recently estimated by the other vehicle, and a plurality of other vehicle estimation points included in the small range are between the first target point and the second target point. It may be regarded as one other vehicle estimation point where the center is arranged, and the road surface μ of the other vehicle estimation point may be estimated based on each road surface μ of the first target point and the second target point.

As a result, when a plurality of other vehicle estimation points exist close to each other, when estimating the road surface μ at each point on the vehicle's course, the plurality of other vehicle estimation points are used as one other vehicle estimation point. Can be treated as. Then, the road surface μ at the other vehicle estimation point at the one point is estimated by preferentially considering the lowest road surface μ among the road surface μ at the plurality of other vehicle estimation points considered to be aggregated at the other vehicle estimation points. NS. Therefore, the road surface μ at each point on the course of the vehicle can be safely estimated with respect to the occurrence of tire slip of the vehicle.

According to the present invention, the road surface μ at each point on the course of the vehicle can be estimated before arriving at that point.

It is a figure which shows the structure of the road surface μ estimation system including the vehicle which mounted the road surface μ estimation device which concerns on one Embodiment of this invention. It is a figure which shows the structure of a vehicle. It is a figure for demonstrating the method of estimating the road surface μ in a vehicle. It is a figure for demonstrating the processing when a plurality of other vehicle estimation points are included in a small area.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Road surface μ estimation system>
FIG. 1 is a diagram showing a configuration of a road surface μ estimation system 1 including a vehicle 2 equipped with a road surface μ estimation device according to an embodiment of the present invention.

The road surface μ estimation system 1 is a system that enables the road surface μ at each point on the course of the vehicle 2 equipped with the road surface μ estimation device to be estimated by the road surface μ estimation device before the vehicle 2 arrives at that point. ..

The road surface μ estimation system 1 includes at least one vehicle 3 in addition to the vehicle 2 equipped with the road surface μ estimation device. The vehicle 3 is a probe car that transmits probe information. The probe information is information such as a traveling point (position) and a vehicle speed of the vehicle 3. The vehicle 3 has a function of estimating the road surface μ of the traveling road surface. The road surface μ is estimated from the wheel speed (rotational speed) of each wheel of the vehicle 3 by a known method. The probe information transmitted from the vehicle 3 includes information on the road surface μ estimated by the vehicle 3 and information on the point where the road surface μ is estimated.

The vehicle 2 may also be a probe car, or the vehicle 3 may be equipped with a road surface μ estimation device.

Further, the road surface μ estimation system 1 includes a road surface μ information providing server 4. The road surface μ information providing server 4 has a communication function with the vehicles 2 and 3, and collects and stores probe information transmitted from each vehicle 3. Then, the road surface μ information providing server 4 generates other vehicle estimation μ information related to the road surface μ estimated by the vehicle 3 and other vehicle estimation point information related to the point where the road surface μ is estimated from the accumulated probe information. , The generated other vehicle estimation μ information and the other vehicle estimation point information are distributed to the vehicle 2.

<Vehicle configuration>
FIG. 2 is a diagram showing the configuration of the vehicle 2.

Vehicle 2 employs an active torque split 4WD system. The vehicle 2 includes an engine 11, a transmission 12, a front differential gear 13, a transfer 14, and a rear differential gear 15.

The engine 11 is mounted (mounted) horizontally on the front portion of the vehicle 2 so that the crankshaft is laterally oriented with respect to the front-rear direction of the vehicle 2, that is, the crankshaft extends in the vehicle width direction.

The transmission 12 may be, for example, a stepped automatic transmission (AT: Automatic Transmission) provided with a labigno type planetary gear mechanism, or a belt type continuously variable transmission (CVT). There may be. Further, the transmission 12 is not limited to these automatic transmissions, and may be a manual transmission (MT).

A ring gear 17 is fixed to the differential case 16 of the front differential gear 13. The rotation of the engine 11 is changed and input to the ring gear 17 by the transmission 12. Due to the rotation input to the ring gear 17, the differential case 16 rotates integrally with the ring gear 17. Then, the rotation of the differential case 16 is converted into the rotation of each side gear 19 via the pinion gear 18, the left and right front drive shafts 21L and 21R rotate integrally with each side gear, and the rotation of the front drive shafts 21L and 21R is the main. It is transmitted to the front wheels 22L and 22R, which are the drive wheels.

For example, the transfer 14 rotates integrally with the first transmission gear 23 that rotates integrally with the differential case 16 of the front differential gear 13, the second transmission gear 24 that meshes with the first transmission gear 23, and the second transmission gear 24. A first bevel gear 25 and a second bevel gear 26 that meshes with the first bevel gear 25 are included. The front end of the propeller shaft 27 extending in the front-rear direction of the vehicle 2 is connected to the center of the second bevel gear 26.

A ring gear 32 is fixed to the differential case 31 of the rear differential gear 15. A bevel gear 33 meshes with the ring gear 32. The power of the propeller shaft 27 is transmitted to the bevel gear 33 via the electronically controlled coupling 34 built in the rear differential gear 15. The electronically controlled coupling 34 includes a main clutch composed of a multi-plate friction clutch that transmits torque and an electromagnet that controls the torque capacity of the main clutch, and an exciting current value supplied to the electromagnet (hereinafter, "coupling current"). A configuration in which the torque capacity of the main clutch increases in proportion to the value) is adopted.

When the power of the propeller shaft 27 is transmitted to the bevel gear 33 via the electronically controlled coupling 34, the power is transmitted from the bevel gear 33 to the ring gear 32, and the differential case 31 rotates integrally with the ring gear 32. Then, the rotation of the differential case 31 is converted into the rotation of each side gear 36 via the pinion gear 35, the left and right rear drive shafts 37L and 37R rotate integrally with each side gear, and the rotations of the rear drive shafts 37L and 37R are secondary respectively. It is transmitted to the rear wheels 38L and 38R, which are the drive wheels.

The vehicle 2 is provided with an ECU (Electronic Control Unit) having a configuration including a microcomputer (microcontroller unit). The microcomputer contains, for example, a non-volatile memory such as a CPU and a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). The vehicle 2 is equipped with a plurality of ECUs in order to control each part. The plurality of ECUs are connected so as to enable bidirectional communication by a CAN (Controller Area Network) communication protocol.

The plurality of ECUs include a 4WD ECU 41 that functions as a road surface μ estimation device. In addition, the plurality of ECUs include, for example, an engine / TMECU 42, an ABS ECU 43, an EPS ECU 44, a meter ECU 45, a body ECU 46, and a DCU ECU 47.

The 4WD ECU 41 estimates the road surface μ at each point on the course of the vehicle 2 based on various information and commands input from other ECUs, and based on the estimated road surface μ and the like, the front wheels 22L, 22R and The distribution of the drive torque to the front wheels 22L, 22R and the rear wheels 38L, 38R is determined so that the tire slip of the rear wheels 38L, 38R does not occur. Then, the 4WD ECU 41 controls the engaged state of the electronically controlled coupling 34 so that the drive torque of the determined distribution is transmitted to the front wheels 22L, 22R and the rear wheels 38L, 38R.

The engine / TMECU 42 executes control of starting, stopping and output adjustment of the engine 11 and control of the gear ratio of the transmission 12 based on various information and commands input from other ECUs.

The ABS ECU 43 has front wheels 22L, 22R and rear wheels 38L so that the posture of the vehicle 2 is kept stable when the vehicle 2 is braking or turning based on various information and commands input from other ECUs. , 38R Controls the braking force applied to each wheel.

The vehicle 2 is equipped with an electric power steering device (EPS: Electric Power Steering) that assists the steering of the steering mechanism by the power of the electric motor. The EPS ECU 44 controls the drive of the electric motor of the electric power steering device based on various information and commands input from other ECUs.

Further, a combination meter is arranged on the instrument panel of the vehicle 2. In addition to instruments such as a speedometer, the combination meter incorporates a multi-information display and the like. The meter ECU 45 controls the operation (display) of each part of the combination meter based on various information and commands input from other ECUs.

The body ECU 46 controls the operation / non-operation of the left and right winkers of the vehicle 2 based on various information and commands input from other ECUs.

A DCU (Data Communication Unit) 48 is connected to the DCU ECU 47. The DCU 48 is a device that performs data communication with the road surface μ information providing server 4 by using mobile wireless data communication, the Internet, or the like. The DCU ECU 47 controls data communication by the DCU 48 based on various information and commands input from other ECUs.

<Estimation of road surface μ>
FIG. 3 is a diagram for explaining a method of estimating the road surface μ in the vehicle 2.

In the vehicle 2, the road surface μ at each point on the course of the vehicle 2 is estimated by the 4WD ECU 41 during the traveling. In order to estimate the road surface μ, the DCU ECU 47 controls the DCU 48 according to a command input from the 4WD ECU 41 to the DCU ECU 47, so that the DCU 48 obtains other vehicle estimation μ information and other vehicle estimation point information distributed from the road surface μ information providing server 4. Receive. As described above, the other vehicle estimated μ information is the information related to the road surface μ estimated by the vehicle 3, and the other vehicle estimated point information is the information related to the point where the road surface μ is estimated. When the DCU 48 receives the other vehicle estimation μ information and the other vehicle estimation point information, the 4WD ECU 41 identifies the other vehicle estimation point as a circular region having a radius A from the other vehicle estimation point information. Then, the road surface μ at the other vehicle estimation point is estimated based on the other vehicle estimation μ information. For example, the value of the road surface μ estimated by the vehicle 3 (other vehicle estimation μ) is estimated as it is as the value of the road surface μ at the other vehicle estimation point, and the estimated value is from the time when the road surface μ is estimated by the vehicle 3. The reliability is set according to the elapsed time of. The reliability is set to a lower value as the elapsed time from the time when the road surface μ is estimated by the vehicle 3 is longer.

The other vehicle estimation point closest to the vehicle 2 in the traveling direction is set as the first other vehicle estimation point P1, and the center of the first other vehicle estimation point P1 is within a predetermined range in the traveling direction from the vehicle 2, that is, within a distance B. Upon entering, the road surface μ from the traveling point P of the vehicle 2 to the estimated first other vehicle P1 (own vehicle estimation μ) is based on the road surface μ of the vehicle's traveling point P and the road surface μ of the first other vehicle estimated point P1. ) Is estimated. At this time, the road surface μ between those points P and P1 linearly changes (changes at a constant rate of change) from the road surface μ = μ0 at the traveling point P to the road surface μ = μ1 at the first other vehicle estimation point P1. Moreover, it is estimated that the closer the position is to the first estimated point P1 of the other vehicle, the closer the road surface μ = μ1 of the first estimated point P1 to the other vehicle.

After the vehicle 2 passes through the first estimated other vehicle P1, a new estimated other vehicle enters within a distance B from the vehicle 2, or the front wheels 22L, 22R and the rear wheels 38L, 38R of the vehicle 2 Until tire slip occurs on any of the wheels, the road surface μ at the first other vehicle estimation point P1 is estimated as the road surface μ at each point on the course.

For example, when tire slip occurs on any of the front wheels 22L, 22R and the rear wheels 38L, 38R of the vehicle 2, the 4WD ECU 41 acquires the wheel speeds of the front wheels 22L, 22R and the rear wheels 38L, 38R. The road surface μ of the traveling point P of the vehicle 2 is estimated from each wheel speed and the like. Each wheel of the front wheels 22L, 22R and the rear wheels 38L, 38R is provided with a wheel speed sensor that outputs a detection signal (pulse signal synchronized with the rotation of the wheels) according to the rotation speed of the wheels, and each wheel speed. Is obtained from the detection signal of the wheel speed sensor. When the road surface μ = μ2 of the traveling point P is estimated from each wheel speed, a new estimated point of another vehicle enters within the range of the distance B from the vehicle 2, or the front wheels 22L, 22R and the rear wheels 38L of the vehicle 2 are entered. Until the tire slip of any of the wheels of, 38R occurs again, the road surface μ = μ2 of the traveling point P is estimated as the road surface μ of each point on the course.

After that, when a new second other vehicle estimation point P2 enters within the range of the distance B from the vehicle 2, the road surface μ = μ2 at the vehicle running point P and the road surface μ = μ3 at the second other vehicle estimation point P2. Based on this, the road surface μ from the traveling point P of the vehicle 2 to the second other vehicle estimation point P2 is estimated. At this time, the road surface μ between those points P and P2 linearly changes (changes at a constant rate of change) from the road surface μ = μ2 at the traveling point to the road surface μ = μ3 at the second vehicle estimation point P2. Moreover, it is estimated that the closer to the second other vehicle estimation point P2, the closer the road surface μ = μ3 of the second other vehicle estimation point P2.

Further, since the elapsed time from the time when the road surface μ = μ3 of the second other vehicle estimation point P2 is estimated by the vehicle 3 is long, for example, the reliability of the road surface μ = μ3 of the second other vehicle estimation point P2 is 0. When set to 5, the road surface μ = μ3 of the second vehicle estimation point P2 has a reliability of the deviation between the road surface μ = μ3 of the second vehicle estimation point P2 and the road surface μ = μ2 of the traveling point P. It is corrected to the value obtained by multiplying the value by 0.5 (μ3-μ2) × 0.5 by adding the road surface μ = μ2 at the traveling point P. Then, the road surface μ between the points P and P2 changes linearly from the road surface μ = μ2 at the traveling point to the road surface μ = μ2 + (μ3-μ2) * 0.5 at the corrected second vehicle estimation point P2. Moreover, it is estimated that the closer to the second other vehicle estimation point P2, the closer the road surface μ = μ2 + (μ3-μ2) × 0.5 of the second other vehicle estimation point P2.

If a new third other vehicle estimation point P3 enters within a distance B from the vehicle 2 before the vehicle 2 reaches the second other vehicle estimation point P2, the road surface μ of the second other vehicle estimation point P2 = Based on μ3 and the road surface μ = μ4 of the third other vehicle estimation point P3, the road surface μ from the second other vehicle estimation point P2 to the third other vehicle estimation point P3 is estimated. At this time, the road surface μ between those points P2-P3 linearly changes from the road surface μ = μ3 at the second vehicle estimation point P2 to the road surface μ = μ4 at the third vehicle estimation point P3, and is the first. 3 It is estimated that the position closer to the other vehicle estimation point P3 is closer to the road surface μ = μ4 of the third other vehicle estimation point P3.

Further, a new fourth other vehicle estimation point P4 enters within the range of the distance B from the vehicle 2, and after the vehicle 2 travels for a while, the fourth other vehicle estimation point P4 has a center in the circular region of the radius A of the fourth other vehicle estimation point P4. 5 When the other vehicle estimated point P5 is within the range of the distance B from the vehicle 2, the road surface μ from the traveling point P of the vehicle 2 to the fourth estimated other vehicle P4 is the road surface μ = μ4 to the fourth of the traveling points. It is estimated that the road surface μ = μ5 of the other vehicle estimation point P4 changes linearly, and the position closer to the fourth other vehicle estimation point P4 is closer to the road surface μ = μ5 of the fourth other vehicle estimation point P4. Will be done. Further, the road surface μ from passing through the 4th other vehicle estimation point P4 to passing through the circular region of the 5th other vehicle estimation point P5 is such that the road surface μ is from the road surface μ = μ4 at the traveling point to the 4th other vehicle. It is estimated that the road surface μ = μ5 at the estimation point P4 changes linearly at a constant rate of change or less.

When the ignition switch of the vehicle 2 is turned off, the road surface μ of the traveling point P of the vehicle 2 at that time is stored in the non-volatile memory of the 4WD ECU 41. Then, when the ignition switch is turned on and the vehicle 2 is started, the road surface μ stored in the non-volatile memory is used to estimate the road surface μ at each point on the course of the vehicle 2.

<Effect>
As described above, based on the road surface μ estimated by the other vehicle 3 and the point where the road surface μ is estimated, the road surface μ at each point on the course of the vehicle 2 is before the vehicle 2 arrives at that point. Can be estimated.

Therefore, the 4WD ECU 41 determines the distribution of the drive torque to the front wheels 22L, 22R and the rear wheels 38L, 38R at each point on the course of the vehicle 2 according to the road surface μ at that point, and determines the distribution of the drive torque to the vehicle 2 Immediately before reaching each point on the course, the electronically controlled coupling 34 so that the drive torque is transmitted to the front wheels 22L, 22R and the rear wheels 38L, 38R in a distribution according to the road surface μ of the reaching point. The engagement state can be controlled. As a result, at a point where the road surface μ is low, the distribution of the drive torque to the rear wheels 38L and 38R, which are the auxiliary drive wheels, can be increased to suppress the occurrence of tire slip on the front wheels 22L and 22R and the rear wheels 38L and 38R. On the other hand, at a point where the road surface μ is high, the running fuel efficiency of the vehicle 2 can be improved by setting the two-wheel drive state in which the drive torque is transmitted only to the front wheels 22L and 22R, which are the main drive wheels.

FIG. 4 is a diagram for explaining processing when a plurality of other vehicle estimation points are included in a circular region having a radius C.

The estimated point of another vehicle is specified as a circular region having a radius A. Therefore, when a plurality of other vehicle estimation points are included in a circle area smaller than the circle area of the radius A, the vehicle 2 passes through the other vehicle estimation point on the front side in the traveling direction and then passes through the next other vehicle estimation point. It may not be possible to change the road surface μ up to from the road surface μ at the other vehicle estimation point in front to the road surface μ at the next other vehicle estimation point at a constant rate of change or less.

Therefore, as shown in FIG. 4, when a plurality of other vehicle estimation points A11, A12, A13, and A14 are included in a circular region having a radius C smaller than the radius A, those other vehicle estimation points A11, A12, A13 and A14 may be treated as one point estimated by another vehicle (hereinafter, this point is referred to as an "aggregation point").

In this case, among those other vehicle estimation points A11, A12, A13, and A14, the other vehicle estimation point having the lowest road surface μ is set as the first target point, and the other vehicle estimation with the road surface μ most recently estimated by the vehicle 3 The point is the second target point. Then, in the estimation of the road surface μ at each point on the course of the vehicle 2, the other vehicle estimation points A11, A12, A13, and A14 included in the circular region of the radius C are between the first target point and the second target point. It is treated as an aggregation point where the center is placed in.

For example, in the example shown in FIG. 4, since the other vehicle estimation points with the lowest road surface μ are the other vehicle estimation points A13 and P14, the other vehicle estimation point A13 with high reliability of the road surface μ is the first target point. It is said that. Further, since the road surface μ is estimated most recently in the vehicle 3, the other vehicle estimation point A12 having the highest reliability of the road surface μ is set as the second target point. The other vehicle estimation points A11, A12, A13, and A14 are treated as one aggregation point whose center is arranged between the first target point A13 and the second target point A12.

Then, the distance D1 from the center of the radius C to the estimated point A12 of the other vehicle is multiplied by the reliability of the road surface μ of the estimated point A12 of the other vehicle, and the distance D2 from the center of the radius C to the estimated point A13 of the other vehicle and the other vehicle The reliability of the road surface μ of the estimated point A13 is multiplied, and the added value of these multiplication values is divided by the sum of the reliability of the road surface μ of the other vehicle estimated point A12 and the reliability of the road surface μ of the other vehicle estimated point A13. Will be done. The value obtained by this calculation is the distance from the center of the circular region having the radius C to the center of the aggregation point.

For example, if the distance D1 from the center of the radius C to the estimated point A12 of the other vehicle is 1 m, and the distance D2 from the center of the radius C to the estimated point A13 of the other vehicle is 10 m, the distance D1 = 1 and the estimated point of the other vehicle The reliability "1.0" of the road surface μ of A12 is multiplied, the distance D2 = 10 is multiplied by the reliability "0.5" of the road surface μ of the other vehicle estimation point A13, and the added value of those multiplication values is multiplied. Is divided by the sum of the reliability "1.0" of the road surface μ at the other vehicle estimation point A12 and the reliability "0.5" of the road surface μ at the other vehicle estimation point A13. The value (1 * 1.0 + 10 * 0.5) / (1.0 + 0.5) = 4 (m) obtained by this calculation is the distance from the center of the circular region of radius C to the center of the aggregation point. ..

Further, the road surface μ of the other vehicle estimation point A12 and the reliability of the road surface μ are multiplied, the road surface μ of the other vehicle estimation point A13 and its reliability are multiplied, and the added value of the multiplication values is estimated by another vehicle. It is divided by the sum of the reliability of the road surface μ at the point A12 and the reliability of the road surface μ at the estimated point A13 of another vehicle. The value obtained by this calculation is the road surface μ of the aggregation point.

For example, the road surface μ = 0.3 at the other vehicle estimation point A12 and the reliability “1.0” of the road surface μ are multiplied, and the road surface μ = 0.2 at the other vehicle estimation point A13 and its reliability “0. 5 ”is multiplied, and the added value of those multiplication values is the reliability of the road surface μ of the other vehicle estimation point A12 “1.0” and the reliability of the road surface μ of the other vehicle estimation point A13 “0.5”. Divide by the sum. The value (0.3 * 1.0 + 0.2 * 0.5) / (1.0 + 0.5) = 0.267 obtained by this calculation is taken as the road surface μ of the aggregation point.

The road surface μ at the aggregation point is estimated by preferentially considering the lowest road surface μ among the road surfaces μ of the plurality of other vehicle estimation points A11, A12, A13, and A14 considered to be aggregated at the aggregation point. Therefore, the road surface μ at each point on the course of the vehicle 2 can be safely estimated with respect to the occurrence of tire slip of the vehicle.

<Modification example>
Although the embodiments of the present invention have been described above, the present invention can also be implemented in other embodiments.

For example, the vehicle 2 employs an active torque split 4WD system, and the rear differential gear 15 has an electronically controlled coupling 34 built-in. However, the present invention can also be applied to a vehicle equipped with a configuration that does not employ the electronically controlled coupling 34, as long as the drive torque can be distributed to the main drive wheels and the sub drive wheels.

Further, in the above-described embodiment, the configuration in which the main drive wheels to which the power is transmitted when the power is not distributed is the front wheels 22L and 22R has been taken up, but the present invention has taken up the configuration in which the power is transmitted when the power is not distributed. It can also be used for vehicles having a configuration in which the wheels are the rear wheels 38L and 38R.

In addition, various design changes can be made to the above-mentioned configuration within the scope of the matters described in the claims.

2: Vehicle 3: Vehicle (other vehicle)
41: 4WD ECU (road surface μ estimation device, information receiving means, first estimation means, second estimation means, third estimation means)

Claims (3)

It is a road surface μ estimation device mounted on a vehicle.
An information receiving means for receiving other vehicle estimation μ information related to the road surface μ estimated by another vehicle and other vehicle estimation point information related to the point where the road surface μ is estimated, and
A first estimation means that estimates the road surface μ of the other vehicle estimation point specified from the other vehicle estimation point information received by the information receiving means based on the other vehicle estimation μ information received by the information receiving means.
The traveling point of the vehicle and the estimation of the first other vehicle are made according to the fact that the first estimated point of the other vehicle, which is the estimated point of the other vehicle, is within a predetermined range in the traveling direction from the vehicle. The road surface μ between the point and the traveling point changes from the road surface μ of the traveling point to the road surface μ of the first other vehicle estimation point estimated by the first estimation means, and is close to the first other vehicle estimation point. A road surface μ estimation device including a second estimation means that estimates the position so that the value becomes closer to the road surface μ at the first other vehicle estimation point. The first other vehicle estimation is performed according to the fact that the second other vehicle estimation point, which is the other vehicle estimation point different from the first other vehicle estimation point, is within the predetermined range in the traveling direction from the vehicle. The road surface μ between the point and the second other vehicle estimation point is changed from the road surface μ of the first other vehicle estimation point to the road surface μ of the second other vehicle estimation point estimated by the first estimation means. The road surface μ according to claim 1, further comprising a third estimation means that estimates that the position closer to the second other vehicle estimation point has a value closer to the road surface μ of the second other vehicle estimation point. Estimator. When a plurality of other vehicle estimation points are included in a small range smaller than the predetermined range, the first estimation means has the lowest road surface μ among the plurality of other vehicle estimation points. Is the first target point, the other vehicle estimation point where the road surface μ is most recently estimated by the other vehicle is the second target point, and a plurality of the other vehicle estimation points included in the small range are the first target points. It is regarded as one other vehicle estimation point whose center is located between the point and the second target point, and the other vehicle estimation point is based on each road surface μ of the first target point and the second target point. The road surface μ estimation device according to claim 1 or 2, wherein the road surface μ is estimated.

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