JP6237317B2 - Snow surface hardness measuring apparatus and snow surface hardness measuring method - Google Patents

Description

  The present invention relates to a snow surface hardness measuring apparatus and a snow surface hardness measuring method for measuring the hardness of a snow surface.

Conventionally, the measurement of the hardness of a snow surface (pressed snow road surface) has been performed by single point measurement with a penetrometer or the like.
Patent Documents 1 and 2 below propose a technique for continuously measuring the hardness of a snow surface by automatic measurement.
For example, in Patent Document 1, a hardness measurement member supported so as to be movable up and down is pressed against a snow surface, and the pressed hardness measurement member is continuously moved on the snow surface. The continuously moving hardness measurement member sequentially measures the sinking amount that sinks to the snow surface, and the hardness on snow is obtained from the measured sinking amount.
Patent Document 2 is a method for measuring the hardness on snow using a tow vehicle that travels while towing the towed object, and pulls the towed object when the towed vehicle travels while slipping on the snow surface. The traction force is detected, and the snow hardness of the snow surface is obtained from the detected traction force.

JP 2006-313128 A JP 2008-175787 A

However, in the above-described conventional technology, there is room for improvement in the measurement accuracy of snow surface hardness.
More specifically, in Patent Document 1, road surface irregularities are not taken into account, and road surface irregularities may cause errors in detection of subsidence. Also, on road surfaces with soft roads or fresh snow, road surface hardness May be underestimated and the measurement results may not be accurate.
Further, since Patent Document 2 estimates the road surface deformation from the longitudinal force at the time of towing without directly measuring the deformation, the measurement result is greatly influenced by the road surface-tire friction characteristics, and the estimation accuracy of the road surface hardness is low. In addition, since the slip ratio is given to the tire, snow moves and the road surface property changes greatly, which may make the test difficult.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to accurately measure the snow surface hardness.

In order to solve the above-described problems and achieve the object, a snow surface hardness measuring apparatus according to the invention of claim 1 includes a wheel-shaped pressing member that moves on the snow surface while applying a constant contact pressure to the snow surface. The snow surface shape for continuously measuring the cross-sectional shape of the snow surface around the passage position of the pressing member before the passage of the pressing member and the cross-sectional shape of the periphery of the passage position after the passage of the pressing member Based on the measurement means and the change in the cross-sectional shape before and after passage of the pressing member, the amount of vertical displacement of the snow surface at each point of the passing position of the pressing member is estimated, and based on the amount of displacement. Processing means for calculating the snow surface hardness at each point of the passing position, and provided in front of the movement direction of the pressing member, and applying the ground pressure to the snow surface before the pressing member passes, Precompression to precompress Characterized in that it comprises a stage, a.
The snow surface hardness measuring apparatus according to a second aspect of the invention is characterized in that the pre-compression means is a member having a planar contact surface having a predetermined length with respect to the moving direction of the pressing member. .
The snow surface hardness measuring apparatus according to a third aspect of the invention is characterized in that the pre-compression means is a wheel-like member that rotates in the same direction as the pressing member.
The snow surface hardness measuring apparatus according to claim 4 is characterized in that a ground pressure applied to the snow surface by the pre-compression means is smaller than a ground pressure applied to the snow surface by the pressing member.
The snow surface hardness measuring apparatus according to claim 5 is characterized in that the width of the ground contact surface of the pre-compression means is larger than the width of the ground contact surface of the pressing member.
The snow surface hardness measurement apparatus according to the invention of claim 6 is characterized in that a contact pressure applied to the snow surface by the pressing member and the pre-compression means is 0.1 MPa or more and 1 MPa or less.
In the snow surface hardness measuring apparatus according to claim 7, the pressing member and the snow surface shape measuring means are attached to the same housing, and the inclination of the housing with respect to the moving direction of the pressing member. A housing posture measuring means for measuring the displacement, and the processing means corrects the cross-sectional shape based on the inclination of the housing measured by the housing posture measuring means to estimate the displacement. It is characterized by.
The snow surface hardness measuring apparatus according to an eighth aspect of the invention is characterized in that the pressing member is a pneumatic tire.
The snow surface hardness measuring apparatus according to claim 9 is characterized in that the pressing member and the pre-compression means are both pneumatic tires.
The snow surface hardness measuring apparatus according to the invention of claim 10 is characterized in that the pressing member and the pre-compression means are attached to the same casing, and the pneumatic tire and the pre-compression means which are the pressing members. The housing is moved using both of the pneumatic tires as drive wheels.
The snow surface hardness measuring apparatus according to the invention of claim 11 is characterized in that the pneumatic tire as the pressing member and the pneumatic tire as the precompression means are steered in opposite phases.
The snow surface hardness measuring apparatus according to the invention of claim 12 applies a ground pressure to the snow surface before passing through the pressing member by a pre-compression means provided in front of the moving direction of the wheel-shaped pressing member. the method comprising the surface to precompression, the conjunction with the pressing member moves on the snow surface while applying a constant ground pressure on the snow surface, said peripheral passage position of the pressing member before the passage of the pressing member A step of continuously measuring the cross-sectional shape of the snow surface, a step of continuously measuring the cross-sectional shape around the passage position after passing through the pressing member, and a change in the cross-sectional shape before and after passing through the pressing member. And a step of estimating a vertical displacement amount of the snow surface at each point of the passing position of the pressing member, and calculating a snow surface hardness at each point of the passing position based on the displacement amount. Characterized in that it includes a step that, a.

According to the present invention, the cross-sectional shape of the snow surface around the passing position of the wheel-shaped pressing member is measured, and the snow surface hardness is calculated based on the amount of vertical displacement of the snow surface before and after the passing of the pressing member. By measuring the position of the snow surface not by a point but by a cross-sectional shape, the measurement accuracy of the snow surface hardness can be improved by minimizing the influence of the snow surface irregularity. Further, since the cross-sectional shape of the snow surface around the pass position as well as the pass position (inside of the cage) of the pressing member is measured, it is possible to easily identify the same point in the cross-sectional shape measured continuously. Measurement accuracy of surface hardness can be improved.
According to the present invention, since the precompression unit is provided in front of the moving direction of the pressing member, a highly reproducible measurement result can be obtained even on a snow surface having a low density such as fresh snow. In addition, since the correlation between the amount of displacement and the hardness of the snow surface is higher on the snow surface that has been pre-compressed than on the snow surface that has not been pre-compressed, the accuracy of measuring the snow surface hardness can be improved. it can.
According to the present invention, since the pre-compression means is a member having a flat contact surface, the pre-compression means is unlikely to be pitched and the like, and the contact pressure can be evenly applied in the traveling direction of the pressing member.
According to the present invention, since the pre-compression means is a wheel-shaped member, a two-wheeled vehicle or a four-wheeled vehicle can be used as a snow surface hardness measuring device.
According to the present invention, since the contact pressure applied to the snow surface by the pre-compression means is smaller than the contact pressure applied to the snow surface by the pressing member, excessive pre-compression can be prevented and measurement sensitivity can be improved.
According to the present invention, since the width of the ground contact surface of the pre-compression means is larger than the width of the ground contact surface of the pressing member, the ground contact surface of the pressing member can be completely pre-compressed, and the measurement reproducibility Can be improved.
According to the present invention, since the ground pressure applied to the snow surface by the pressing member and the pre-compression means is 0.1 MPa or more and 1 MPa or less, the ground pressure necessary for deforming (compressing) the snow and a normal wheel shape are obtained. It can be within the contact pressure range of the member.
According to the present invention, the amount of displacement is estimated by correcting the cross-sectional shape based on the inclination of the casing to which the pressing member and the snow surface shape measuring means are attached. Therefore, the influence of rolling, pitching, and road surface gradient of the casing The measurement error due to can be corrected, and the estimation accuracy of the snow surface hardness can be improved.
According to the present invention, since the pneumatic tire is used as the pressing member, it is possible to measure the snow surface hardness of a range suitable for grasping the state of the traveling road surface (traveling snow surface) in the performance evaluation test of the pneumatic tire. it can.
According to the present invention, since the pressing member and the pre-compression means are both pneumatic tires, a general two-wheeled vehicle or four-wheeled vehicle equipped with a pneumatic tire can be used as a snow surface hardness measuring device. .
According to the present invention, since the casing is moved using both the pneumatic tire as the pressing member and the pneumatic tire as the pre-compression means as the driving wheels, the measurement error due to the influence of the force applied during driving can be minimized. it can.
According to the present invention, the pneumatic tire that is the pressing member and the pneumatic tire that is the pre-compression means are steered in opposite phases, so the front wheel (pneumatic tire that is the pre-compression means) and the rear wheel (pressing force) are also turned during the turn. The saddle of the pneumatic tire, which is a member, can be placed at the same position, and the snow surface hardness on a curved road can be measured.
According to the present invention, the cross-sectional shape of the snow surface around the passing position of the wheel-shaped pressing member is measured, and the snow surface hardness is calculated based on the amount of vertical displacement of the snow surface before and after the passing of the pressing member. By measuring the position of the snow surface not by a point but by a cross-sectional shape, the measurement accuracy of the snow surface hardness can be improved by minimizing the influence of the snow surface irregularity. Further, since the cross-sectional shape of the snow surface around the pass position as well as the pass position (inside of the cage) of the pressing member is measured, it is possible to easily identify the same point in the cross-sectional shape measured continuously. Measurement accuracy of surface hardness can be improved.
According to the present invention, since the precompression unit is provided in front of the moving direction of the pressing member, a highly reproducible measurement result can be obtained even on a snow surface having a low density such as fresh snow. In addition, since the correlation between the amount of displacement and the hardness of the snow surface is higher on the snow surface that has been pre-compressed than on the snow surface that has not been pre-compressed, the accuracy of measuring the snow surface hardness can be improved. it can.

It is explanatory drawing which shows the structure of the snow surface hardness measuring apparatus 10 concerning Embodiment 1. FIG. 3 is a block diagram showing a functional configuration of a processing unit 106. FIG. It is explanatory drawing which shows an example of the measured value of the cross-sectional shape of the snow surface G obtained by the snow surface shape measuring means 104. It is explanatory drawing which shows an example of the cross-sectional shape of the collar F with a tread pattern. 3 is a flowchart showing processing by the snow surface hardness measurement apparatus 10; It is explanatory drawing which shows the structure of the snow surface hardness measuring apparatus 20 concerning Embodiment 2. FIG. It is explanatory drawing which shows the other structure of the snow surface hardness measuring apparatus 20 concerning Embodiment 2. FIG. It is a graph (condition with pre-compression) which shows the performance evaluation test result of the snow surface hardness measuring apparatus concerning this invention. It is a graph (condition without pre-compression) which shows the performance evaluation test result of the snow surface hardness measuring apparatus concerning this invention. It is a graph which shows the standard deviation of the measurement result (snow surface hardness) in each measurement condition. It is a graph which shows the average value of the measurement result (snow surface hardness) in each measurement condition. It is a graph which compares the snow surface hardness measured with the snow surface hardness measuring apparatus with the snow surface hardness measured at a single point.

  Exemplary embodiments of a snow surface hardness measuring apparatus and a snow surface hardness measuring method according to the present invention will be described below in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is an explanatory diagram illustrating a configuration of a snow surface hardness measurement apparatus 10 according to the first embodiment.
The snow surface hardness measuring apparatus 10 according to the first embodiment includes a wheel-shaped pressing member 102, a snow surface shape measuring unit 104 (104A, 104B), a processing unit (processing unit) 106, and an attitude angle sensor (housing). (Orientation measuring means) 108 and a housing 120.
The measurement result by the snow surface hardness measurement device 10 is used, for example, to grasp the state of the traveling road surface (traveling snow surface) in a snow tire performance evaluation test.

The pressing member 102 moves on the snow surface G while applying a constant ground pressure L1 to the snow surface G.
In the present embodiment, the pressing member 102 is a pneumatic tire.
Although only one pressing member 102 is illustrated in FIG. 1, two pneumatic tires having a common central axis O may be arranged side by side with respect to the traveling direction. In that case, the measurement of the snow surface hardness described later may be performed by only one pressing member 102 (pneumatic tire), or may be performed by both pressing members 102 (pneumatic tires).
In the snow surface hardness measuring apparatus 10, the pressing member 102 is formed into a wheel shape because the ground pressure on the snow surface G is insufficient in a warp or an endless track that is an example of other moving and ground pressure maintaining means, This is because there is a possibility that a measurement value in a range suitable for snow surface hardness measurement during the tire performance evaluation test may not be obtained.
Note that the contact pressure L1 from the pressing member 102 is obtained by dividing the load from the pressing member 102 to the snow surface G (ground contact load) by the contact area of the pressing member 102 (the area included in the outline of the planar ground shape). Value.

In the present embodiment, it is assumed that the pressing member 102 moves in the arrow R direction (the left direction in the drawing).
The movement of the pressing member 102 and the housing 120 is performed, for example, by pulling the housing 120 with another vehicle, a winch, or the like, or by driving the pressing member 102 with a motor or the like.
In addition, it is preferable that the moving speed during measurement by the snow surface hardness measuring apparatus 20 is constant. This is because the impact (how the ground pressure is applied) from the pressing member 102 to the snow surface G changes according to the moving speed of the snow surface hardness measuring device 20, and the amount of compression of the snow surface G may change. It is.
Further, when the snow surface hardness measuring device 20 is moved by driving the pressing member 102, it is preferable to drive with the minimum driving force. This is because a shear stress is applied to the snow surface G from the driving wheel, so that the state of the snow surface G may change and affect the measurement. By minimizing the driving force of the driving wheel, the influence exerted on the snow surface G by the force applied during driving can be minimized.

The snow surface shape measuring means 104 (104A, 104B) includes a cross-sectional shape of the snow surface G around the passing position of the pressing member 102 before passing the pressing member 102, and a cross-sectional shape around the passing position after passing the pressing member 102. , Are measured continuously.
In the present embodiment, laser line scanners 104A and 104B are used as the snow surface shape measuring means 104.
A laser line scanner 104A is installed on the front side with respect to the traveling direction of the pressing member 102, and measures the cross-sectional shape of the snow surface G around the passing position before the pressing member 102 passes. Further, a laser line scanner 104B is installed on the rear side with respect to the traveling direction of the pressing member 102, and the cross-sectional shape of the snow surface G around the passing position after the pressing member 102 passes is measured.
As the snow surface shape measuring means 104, for example, a stereo camera may be used. Also, the snow surface shape measuring means 104 may be combined with a plurality of measuring devices such as a laser line scanner and a stereo camera.
The vicinity of the passage position of the pressing member 102 is the snow surface G including the hail formed by the passage of the pressing member 102 and its periphery. By measuring the shape of the snow surface G around the ridge as well as the ridge, correspondence between the measurement values obtained by the two laser line scanners 104A and 104B (specification of measurement values at the same point) can be taken with high accuracy. .
Continuous measurement means, for example, from receiving a hardness measurement start instruction to the snow surface hardness measurement apparatus 10 until receiving a hardness measurement end instruction.
In the present embodiment, the pressing member 102 and the snow surface shape measuring means 104 are attached to the same casing 120. The measurement result by the snow surface shape measuring unit 104 is output to the processing unit 106.

The posture angle sensor 108 is a housing posture measuring unit that measures the inclination of the housing 120 with respect to the moving direction of the pressing member 102.
The attitude angle sensor 108 is an inertial measurement unit (IMU) or the like, and detects the rolling and pitching of the housing 120, the inclination due to the road surface gradient, and the like.
The measurement value obtained by the attitude angle sensor 108 is output to the processing unit 106.

The processing unit 106 estimates the amount of vertical displacement of the snow surface G at each point of the passing position of the pressing member 102 based on the change in the cross-sectional shape of the snow surface G before and after the passing of the pressing member 102, and the displacement Based on the quantity, the snow surface hardness at each point of the passing position is calculated.
Specifically, the processing unit 106 is an interface that interfaces with a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an EEPROM that holds various data in a rewritable manner, a peripheral circuit, and the like. Part.
Note that although the processing unit 106 is provided in the housing 120 in this embodiment, the processing unit 106 may be provided outside the housing 120. In this case, for example, the snow surface shape measuring unit 104 is provided with a communication function so that the measurement result is transmitted to the processing unit 106.

FIG. 2 is a block diagram illustrating a functional configuration of the processing unit 106.
The processing unit 106 realizes a displacement amount estimation unit 1062 and a hardness calculation unit 1064 when the CPU executes the control program.
The displacement amount estimation unit 1062 estimates the displacement amount of the snow surface G in the vertical direction at each point of the passing position of the pressing member 102 based on the change in the cross-sectional shape of the snow surface G before and after the passage of the pressing member 102.

Here, the displacement amount estimation unit 1062 estimates the displacement amount of the snow surface G in the vertical direction using the measurement result of the cross-sectional shape of the snow surface G obtained by the snow surface shape measuring unit 104.
FIG. 3 is an explanatory diagram showing an example of a measured value of the cross-sectional shape of the snow surface G obtained by the snow surface shape measuring means 104.
3A is a cross-sectional shape P1 before passing the pressing member 102 obtained by the laser line scanner 104A, FIG. 3B is a cross-sectional shape P2 after passing the pressing member 102 obtained by the laser line scanner 104B, and FIG. 3C is a cross-sectional view. The shapes P1 and P2 are superimposed.
The cross-sectional shape P1 before the passage of the pressing member 102 shown in FIG. 3A is substantially flat, whereas the cross-sectional shape P2 after the passage of the pressing member 102 shown in FIG. 3B has a ridge F at the center.

Since the cross-sectional shapes shown in FIGS. 3A and 3B are continuously measured, the displacement amount estimation unit 1062 first determines the measurement values obtained by the laser line scanner 104A and the measurement values obtained by the laser line scanner 104B. From the above, the cross-sectional shape obtained at the same location is specified.
Specifically, for example, a time stamp indicating the measurement time is given to each measurement value obtained by the laser line scanner 104A and the laser line scanner 104B.
The displacement amount estimation unit 1062 determines the time T1 when the measurement range of the laser line scanner 104A has passed the predetermined point Y and the laser from the distance between the laser line scanner 104A and the laser line scanner 104B and the moving speed of the pressing member 102, for example. The time T2 when the measurement range of the line scanner 104B passes the predetermined point Y is specified.
Then, the measurement value obtained by the laser line scanner 104A at time T1 and the measurement value obtained by the laser line scanner 104B at time T2 are identified as the cross-sectional shape obtained at the same location.
If the moving speed of the pressing member 102 is constant, once the measured values of the two laser line scanners 104A and 104B are taken, the measured values may be shifted by the same time thereafter.

Next, as shown in FIG. 3C, the displacement amount estimation unit 1062 estimates the displacement amount D by superimposing the cross-sectional shapes P1 and P2 obtained at the same location.
At this time, the cross-sectional shape P2 after passing through the pressing member 102 is used to identify the ground contact width W1 of the pressing member 102 that is the width of the ridge F (the width of the ridge F), and the position of the sectional shape outside the ridge F is aligned. Thus, the positions of the snow surfaces G in the two cross-sectional shapes are aligned. For example, the shape outside the ridge F in two cross-sectional shapes may be pattern-matched using a cross-correlation function or the like.
Then, the displacement amount estimation unit 1062 calculates the average positions of the cross-sectional shapes P1 and P2 in the range of the contact width W1.
That is, the dotted line V1 in FIG. 3C is the average position of the cross-sectional shape P1 in the range of the grounding width W1, and the dotted line V2 is the average position of the cross-sectional shape P2 in the range of the grounding width W1.
Thereby, the minute unevenness | corrugation of cross-sectional shape P1, P2 etc. are smoothed.
Then, the displacement amount estimation unit 1062 estimates the difference between the average positions of the cross-sectional shapes P1 and P2 in the range of the ground contact width W1 as the displacement amount D in the vertical direction of the snow surface G.

In addition, when there is a pattern (tread pattern) on the ground contact surface (tread surface in the case of a pneumatic tire) of the pressing member 102, an uneven pattern M may be formed in the cross-sectional shape of the heel F as shown in FIG. is there.
In such a case, if the average position of the cross-sectional shape P2 is simply calculated, the position higher than the bottom surface of the flange F becomes the average position of the cross-sectional shape P2, and the estimation accuracy of the displacement amount D decreases.
Therefore, when a pattern is provided on the ground contact surface of the pressing member 102, the envelope P2 ′ of the cross-sectional shape P2 within the ground contact width W1 is set as the average position as shown in FIG.

Further, the displacement amount estimation unit 1062 may correct the cross-sectional shape (measured values of the laser line scanners 104A and 104B) using the measured values of the attitude angle sensor 108.
More specifically, the measured values of the laser line scanners 104A and 104B are removed by removing components other than the vertical direction using the posture angle (roll angle, pitch angle, etc.) of the housing 120 measured by the posture angle sensor 108. Perform the correction.
In this case, the measurement error of the cross-sectional shape due to the deviation of the posture of the housing 120 can be corrected, and the measurement accuracy of the road surface hardness can be improved.

Returning to the description of FIG. 2, the hardness calculation unit 1064 calculates the snow surface hardness at each point of the passing position of the pressing member 102 based on the displacement amount D of the snow surface G.
The hardness calculation unit 1064 converts the displacement amount D into a hardness value (CTI value or the like) using, for example, a regression equation. In this regression equation, the road surface hardness is inversely proportional to the displacement amount D and proportional to the ground pressure L1 from the pressing member 102. If the contact pressure L1 is constant, the regression equation of the road surface hardness may use only the displacement amount D as an explanatory variable.

FIG. 5 is a flowchart showing processing by the snow surface hardness measurement apparatus 10.
In the flowchart of FIG. 5, the processing for one point I on the snow surface G will be described. Actually, the snow surface hardness measurement apparatus 10 continuously performs the following processing to continuously measure the hardness of the snow surface G.
First, the snow surface hardness measurement apparatus 10 measures the cross-sectional shape P1 of the point I before passing the pressing member 102 by the laser line scanner 104A (step S10).
When the pressing member 102 passes through the point I (step S12), the cross-sectional shape P2 of the point I after passing through the pressing member 102 is measured by the laser line scanner 104B (step S14).
Next, the processing unit 106 identifies the cross-sectional shapes P1 and P2 at the point I (same point) from the cross-sectional shapes continuously output from the laser line scanners 104A and 104B (step S16), and within the grounding width W1. Are averaged (step S18). Subsequently, the processing unit 106 estimates the difference in the positions of the averaged cross-sectional shapes P1, P2 as the displacement amount D (step S20).
And the snow surface hardness of the point I is calculated using the regression formula which converts the displacement amount D into hardness (step S22), and the process by this flowchart is complete | finished.

As described above, the snow surface hardness measuring apparatus 10 according to the first embodiment measures the cross-sectional shape of the snow surface G around the passing position of the wheel-shaped pressing member 102, and the snow surface before and after the passing of the pressing member 102. The snow surface hardness is calculated based on the vertical displacement amount D of G. By measuring the position of the snow surface G not by a point but by a cross-sectional shape, the measurement accuracy of the snow surface hardness can be improved by minimizing the influence of irregularities on the snow surface G.
Further, since the cross-sectional shape of the snow surface G around the passing position as well as the passing position (inside the cage) of the pressing member 102 is measured, it is possible to easily identify the same point in the continuously measured cross-sectional shapes. In addition, the measurement accuracy of snow surface hardness can be improved.
Further, since the snow surface hardness measuring apparatus 10 corrects the cross-sectional shape based on the inclination of the housing 120 to which the pressing member 102 and the snow surface shape measuring means 104 are attached, the displacement amount D is estimated. Measurement errors due to the effects of rolling, pitching and road surface gradient can be corrected, and the accuracy of snow surface hardness estimation can be improved.
Moreover, since the snow surface hardness measuring apparatus 10 uses a pneumatic tire as the pressing member 102, the snow surface hardness of a range suitable for grasping the state of the traveling road surface (traveling snow surface) in the performance evaluation test of the pneumatic tire. Can be measured.

(Embodiment 2)
In the second embodiment, an example in which pre-compression means for pre-compressing the snow surface G before passing through the pressing member 102 is provided in addition to the configuration of the first embodiment.
In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 6 is an explanatory diagram of a configuration of the snow surface hardness measurement apparatus 20 according to the second embodiment.
The snow surface hardness measuring apparatus 20 according to the second embodiment is provided in front of the movement direction of the pressing member 102 in addition to the configuration of the snow surface hardness measuring apparatus 10 shown in FIG. Pre-compression means 110 that pre-compresses the snow surface G by applying a contact pressure to the surface G is further provided.
In the present embodiment, the pressing member 102 and the pre-compression means 110 are attached to the same casing 120.
By pre-compressing the snow surface G before passing through the pressing member 102 using the pre-compression means 110, a highly reproducible measurement result can be obtained even for a snow surface G having a low density such as fresh snow. In addition, as will be described later, the snow surface G that has been pre-compressed has a higher correlation between the amount of displacement D and the hardness than the snow surface that has not been pre-compressed. Can be improved.

In FIG. 6, a sled 110 </ b> A is employed as the precompression unit 110. The pre-compression means 110 may be configured to be able to move on the snow surface G while applying a constant contact pressure L2 to the snow surface G, and may be, for example, an endless track other than the sled 110A. That is, the pre-compression means 110 in this case is a member having a planar grounding surface having a predetermined length with respect to the moving direction of the pressing member 102.
When an endless track is used as the precompression means 110, it is preferable that the endless track be a driving wheel and the pressing member 102 be a driven wheel. This is because when the pressing member 102 is a drive wheel, the measurement accuracy may be reduced due to friction between the pressing member 102 and the snow surface G or the like.
When the pre-compression means 110 is the sled 110A, for example, the pressing member 102 and the casing 120 are moved by pulling the casing 120 with another vehicle, a winch or the like, or driving the pressing member 102 with a motor or the like. .

In addition, it is preferable that the moving speed during measurement by the snow surface hardness measuring apparatus 20 is constant. This is because the impact (how the ground pressure is applied) from the pre-compression means 110 and the pressing member 102 to the snow surface G changes according to the moving speed of the snow surface hardness measuring device 20, and the compression amount of the snow surface G changes. This is because there is a possibility.
Further, when the pre-compression means 110 or the pressing member 102 is driven to move the snow surface hardness measuring device 20, it is preferable to drive with the minimum driving force. This is because a shear stress is applied to the snow surface G from the driving wheel, so that the state of the snow surface G may change and affect the measurement. By minimizing the driving force of the driving wheel, the influence exerted on the snow surface G by the force applied during driving can be minimized.

Further, the ground pressure L2 applied to the snow surface G by the pre-compression means 110 is set to be smaller than the ground pressure L1 applied to the snow surface G by the pressing member 102.
This is because when the ground pressure L2 applied to the snow surface G by the pre-compression means 110 becomes larger than the ground pressure L1 applied to the snow surface G by the pressing member 102, the pre-compression is excessive and the measurement sensitivity decreases (the pressing member 102). This is because the compression of the snow surface G due to the above is extremely small).
Note that the contact pressure L2 from the precompression unit 110 is the load applied to the snow surface G from the precompression unit 110 (contact load) by the contact area of the pressing member 102 (the area within the range included in the contour of the planar contact shape). The value divided by.

Further, the width of the ground contact surface (ground contact width) of the pre-compression means 110 is made larger than the width (ground contact width) of the ground contact surface of the pressing member 102.
This is because if the ground contact width of the pre-compression means 110 is smaller than the ground contact width of the pressing member 102, the pressing member 102 compresses a region where the pre-compression is not performed, and the reproducibility of the measurement is lowered.

Further, the ground pressure applied to the snow surface G by the pressing member 102 and the pre-compression means 110 is set to 0.1 MPa or more and 1 MPa or less.
The reason why the contact pressure is 0.1 MPa or more is that the contact pressure required for the snow surface G to undergo destructive deformation (plastic deformation) is generally 0.1 MPa or more.
The reason why the contact surface pressure is 1 MPa or less is that the contact surface pressure of a normal pneumatic tire is about 1 MPa or less.
When the snow surface G has a particularly high hardness, the measurement sensitivity is improved by increasing the contact surface pressure. In addition, when the hardness of the snow surface G is particularly low, the reproducibility of the measurement is improved by reducing the contact surface pressure.
That is, more reliable measurement can be performed by changing the contact surface pressure from the pressing member 102 and the pre-compression means 110 using the approximate value of the hardness of the snow surface G to be measured.
When the contact surface pressure from the pressing member 102 and the precompression unit 110 is changed (for example, when the contact pressure from the pressing member 102 or the precompression unit 110 is changed, or when the grounding pressure of the pressing member 102 or the precompression unit 110 is changed). When the area is changed, etc.), the regression equation for converting the displacement D into the hardness is calculated again.

FIG. 7 is an explanatory diagram of another configuration of the snow surface hardness measurement apparatus 20 according to the second embodiment.
FIG. 7 shows an example in which a pneumatic tire 110 </ b> B is employed as the pre-compression unit 110, similarly to the pressing member 102. That is, the pre-compression means 110 in this case is a wheel-like member that rotates in the same direction as the pressing member 102, and both the pressing member 102 and the pre-compression means 110 are pneumatic tires.
As described above, when both the pre-compression unit 110 and the pressing member 102 are pneumatic tires, the housing 120 is configured using both the pneumatic tire as the pressing member 102 and the pneumatic tire as the pre-compression unit 110 as drive wheels. It is desirable to move it.
Thereby, the measurement error by the drive of a pneumatic tire can be minimized.

Further, it is desirable to steer the pneumatic tire as the pressing member 102 and the pneumatic tire as the pre-compression means 110 in opposite phases.
Thereby, even when the casing 120 is turning, the front wheel and the rear wheel are in the same position, and measurement is possible even when the snow surface G to be measured is a curved road or the like.

A snow surface hardness measurement method according to Embodiment 2 will be described.
In the case where the pre-compression means 110 is provided in the snow surface hardness measuring device 20, the pressing member 102 is provided by the pre-compression means 110 provided in front of the movement direction of the pressing member 102 before step S10 in the flowchart of FIG. A step of pre-compressing the snow surface G by applying a contact pressure to the snow surface G before passing is performed.

As described above, the snow surface hardness measurement apparatus 20 according to the second embodiment is provided with the pre-compression means 110 in front of the moving direction of the pressing member 102, so that the snow surface G has a low density like fresh snow. However, highly reproducible measurement results can be obtained. Moreover, since the correlation between the amount of displacement D and the hardness of the snow surface G is higher in the pre-compressed snow surface G than in the non-pre-compressed snow surface G, the measurement accuracy of the snow surface hardness is improved. Can be improved.
Further, in the snow surface hardness measuring apparatus 20, if the pre-compression means 110 is a member having a flat grounding surface, the pre-compression means 110 is less likely to be pitched and the like, and the pressing member 102 is grounded evenly in the traveling direction. Pressure can be applied.
Further, in the snow surface hardness measuring device 20, if the pre-compression means 110 is a wheel-shaped member, a two-wheeled vehicle or a four-wheeled vehicle can be used as the snow surface hardness measuring device.
Further, in the snow surface hardness measuring apparatus 20, if the ground pressure applied to the snow surface G by the pre-compression means 110 is made smaller than the ground pressure applied to the snow surface by the pressing member 102, excessive pre-compression is prevented and measurement sensitivity is increased. Can be improved.
Further, in the snow surface hardness measuring apparatus 20, if the width of the ground contact surface of the pre-compression means 110 is made larger than the width of the ground contact surface of the pressing member 102, the ground contact surface of the pressing member 102 is all pre-compressed. Measurement reproducibility can be improved.
Further, in the snow surface hardness measuring apparatus 20, if the contact pressure applied to the snow surface G by the pressing member 102 and the pre-compression means 110 is 0.1 MPa or more and 1 MPa or less, the snow surface G is deformed (compressed). The required contact pressure can be within the contact pressure range of a normal wheel-like member.
Further, in the snow surface hardness measuring device 20, if both the pressing member 102 and the pre-compression means 110 are pneumatic tires, a general two-wheeled vehicle or four-wheeled vehicle equipped with the pneumatic tire can be used as a snow surface hardness measuring device. It can be.
Further, in the snow surface hardness measurement apparatus 20, the housing 120 is moved using both the pneumatic tire as the pressing member 102 and the pneumatic tire as the pre-compression means 110 as drive wheels, so measurement is performed by the influence of the force applied during driving. Errors can be minimized.
Further, in the snow surface hardness measuring device 20, if the pneumatic tire as the pressing member 102 and the pneumatic tire as the pre-compression means 110 are steered in opposite phases, the front wheels (pre-compression means) are also turned. The wrinkles of the pneumatic tire) and the rear wheel (pneumatic tire which is a pressing member) can be set at the same position, and the snow surface hardness on the curved road can be measured.

Examples of the present invention will be described below.
FIGS. 8 and 9 are graphs showing the results of continuous measurement of snow surface hardness for a certain distance using the snow surface hardness measuring apparatus according to the present invention. FIG. 8 shows pre-compression performed by the pre-compression means 110. 9 shows the measurement results (corresponding to the second embodiment: conditions with pre-compression), and FIG. 9 shows the measurement results when the pre-compression means 110 does not perform pre-compression (corresponding to the first embodiment: conditions without pre-compression). ing.
8 and 9, the vertical axis represents the snow surface hardness (CTI conversion value), and the horizontal axis represents the distance from the measurement start point. 8 and 9 show the snow surface hardness measured with the snow surface hardness measuring apparatus according to the present invention, the snow surface hardness measured with the snow surface hardness measuring apparatus according to the prior art, and a single point measurement with a penetrometer. The snow surface hardness is plotted.
In addition, about the prior art, the snow hardness measuring apparatus equivalent to claim 11 of the cited document 1 was used.

FIG. 10 is a graph showing the standard deviation of the measurement result (snow surface hardness) under each measurement condition, and FIG. 11 is a graph showing the average value of the measurement result (snow surface hardness) under each measurement condition.
This measurement is performed by mounting a pneumatic tire on a four-wheel vehicle (hatchback vehicle) having a displacement of 1.6 L and an AWD. The tire sizes of the pneumatic tires are F: 225 / 45R17, R: 195 / 65R15 (both studless tires), the tread width is F: 1400mm, R: 1400mm, and the front and rear are aligned using wheel spacers ing.
The wheel (measurement wheel) used as the pressing member 102 was a rear wheel (R) in a condition with pre-compression and a front wheel (F) in a condition without pre-compression.
The pneumatic pressure of the pneumatic tire was F: 180 kPa, R: 350 kPa, the single wheel load was F: 4 kPa, R: 4 kPa, and the contact pressure was F: 0.20 MPa, R: 0.34 MPa.
As the snow surface shape measuring means 104, two laser line scanners were installed before and after the measuring wheel. In addition, an inertial measurement device (IMU) was used as the housing posture measuring means (posture angle sensor 108). In addition, a GPS distance / speed meter was used to measure the travel speed and travel distance of the vehicle.
The traveling method was to maintain a speed of 10 ± 2 km / h and perform straight traveling.

The snow surface used for this measurement has a constant snow surface hardness. That is, it can be estimated that the more the snow surface hardness measured by the on-snow hardness measuring device is constant, the closer to the true snow surface hardness.
Comparing the snow surface hardness values in FIGS. 8 and 9, it can be seen that the values of the prior art and the present invention are more consistent with the present invention, and the degree of agreement with the actual road surface condition (constant hardness) is higher. .
Further, when the pre-compression condition shown in FIG. 8 is compared with the pre-compression condition shown in FIG. 9, the measured value is more stable in the pre-compression condition shown in FIG. ) And the agreement is high.
Further, when comparing the standard deviations of the measured values shown in FIG. 10, the standard deviation of the measured values in the prior art is the highest, and the difference from the actual road surface having the constant snow surface hardness is the largest.
On the other hand, the present invention has a standard deviation of less than half of the conditions with pre-compression and the condition without pre-compression compared to the prior art. It turns out that it can measure accurately.
In addition, the standard deviation under conditions with pre-compression is almost the same value as single-point measurement, and the actual snow surface hardness can be measured more accurately under conditions with pre-compression than with conditions without pre-compression. I understand that.
Further, as shown in FIG. 11, the measured values in the present invention are close to the measured values obtained by single-point measurement in both the pre-compression condition and the non-pre-compression condition, compared with the prior art. It can be seen that the actual snow surface hardness can be measured more accurately than in the prior art.

FIG. 12 is a graph comparing the snow surface hardness measured by the snow surface hardness measuring apparatus with the snow surface hardness measured at a single point.
In FIG. 12, the vertical axis represents the snow surface hardness (CTI converted value) measured by the snow surface hardness measuring apparatus according to the present invention and the prior art, and the horizontal axis represents the snow surface hardness (CTI) measured by a single point with a penetrometer.
Among the measurement values of the snow surface hardness measurement apparatus according to the present invention, the measurement values under the pre-compression condition agree with the single-point measurement values in a wide range.
In addition, among the measurement values of the snow surface hardness measurement apparatus according to the present invention, the measurement value under the pre-compression condition is slightly less accurate in the region where the CTI is low (the snow is soft) compared to the pre-compression condition. ing.
On the other hand, the measured value measured by the snow surface hardness measuring apparatus according to the prior art is significantly lower than the single-point measured value in the region where the CTI is low (the snow is soft).
As described above, in the snow surface hardness measuring apparatus according to the present invention and the prior art, the displacement amount D is converted into a hardness value (CTI value, etc.) using a regression equation. In the apparatus, an error is likely to occur particularly in a region where the CTI is low, and it is difficult to measure the snow surface hardness in a wide range as in the present invention.

As described above, the snow hardness measuring apparatus according to the present invention can measure the actual snow surface hardness more accurately than the snow hardness measuring apparatus according to the prior art.
In addition, the actual snow surface hardness can be measured more accurately when the pre-compression is performed as in the second embodiment than when the pre-compression is not performed as in the first embodiment.

  DESCRIPTION OF SYMBOLS 10,20 ... Snow surface hardness measuring apparatus, 102 ... Pressing member, 104 ... Snow surface shape measuring means, 104A, 104B ... Laser line scanner, 106 ... Processing part, 1062 ... Displacement amount estimation part, 1064 ...... Hardness calculation unit 108... Posture angle sensor 110... Precompression means 110 A.

Claims (12)

A wheel-shaped pressing member that moves on the snow surface while applying a constant contact pressure to the snow surface;
Snow surface shape measurement for continuously measuring the cross-sectional shape of the snow surface around the passage position of the pressing member before passage of the pressing member and the cross-sectional shape of the periphery of the passage position after passage of the pressing member. Means,
Based on the change in the cross-sectional shape before and after the passage of the pressing member, the amount of vertical displacement of the snow surface at each point of the passage position of the pressing member is estimated, and the passage position based on the amount of displacement. Processing means for calculating the snow surface hardness at each of the points;
Pre-compression means that is provided in front of the movement direction of the pressing member and pre-compresses the snow surface by applying a contact pressure to the snow surface before passing through the pressing member;
A snow surface hardness measuring apparatus comprising: The pre-compression means is a member having a planar grounding surface having a predetermined length with respect to the moving direction of the pressing member.
The snow surface hardness measuring apparatus according to claim 1 . The pre-compression means is a wheel-shaped member that rotates in the same direction as the pressing member.
The snow surface hardness measuring apparatus according to claim 1 . The contact pressure applied to the snow surface by the pre-compression means is smaller than the contact pressure applied to the snow surface by the pressing member,
The snow surface hardness measuring device according to any one of claims 1 to 3 , wherein The width of the ground contact surface of the pre-compression means is larger than the width of the ground contact surface of the pressing member,
The snow surface hardness measuring device according to any one of claims 1 to 4 , wherein The ground pressure applied to the snow surface by the pressing member and the pre-compression means is 0.1 MPa or more and 1 MPa or less.
The snow surface hardness measuring device according to any one of claims 1 to 5 , wherein The pressing member and the snow surface shape measuring means are attached to the same housing,
A housing posture measuring means for measuring the inclination of the housing with respect to the moving direction of the pressing member;
The processing means corrects the cross-sectional shape based on the inclination of the casing measured by the casing posture measuring means, and estimates the displacement amount.
The snow surface hardness measuring device according to any one of claims 1 to 6 , wherein The pressing member is a pneumatic tire.
The snow surface hardness measuring apparatus according to any one of claims 1 to 7 , wherein The pressing member and the pre-compression means are both pneumatic tires.
The snow surface hardness measuring apparatus according to claim 3 . The pressing member and the pre-compression means are attached to the same housing,
Moving the housing using both the pneumatic tire as the pressing member and the pneumatic tire as the pre-compression means as drive wheels;
The snow surface hardness measuring apparatus according to claim 9 . Steering the pneumatic tire as the pressing member and the pneumatic tire as the pre-compression means in opposite phases;
The snow surface hardness measuring apparatus according to claim 9 or 10 , characterized in that Pre-compressing the snow surface by applying a contact pressure to the snow surface before passing through the pressing member by pre-compression means provided in front of the moving direction of the wheel-shaped pressing member;
With displaced on the snow surface while applying a constant ground pressure on the snow surface with the pressing member, continuously cross-sectional shape of the snow surface near the passage position of the pressing member before the passage of the pressing member Measuring to
Continuously measuring the cross-sectional shape around the passing position after passing the pressing member;
Estimating a vertical displacement amount of the snow surface at each point of the passing position of the pressing member based on a change in the cross-sectional shape before and after the passing of the pressing member;
Calculating a snow surface hardness at each point of the passing position based on the amount of displacement;
A snow surface hardness measurement method comprising:

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