JP6996710B2 - Input power estimation system and input power estimation method for the rotating body, as well as contact surface condition determination system and mobile device control system. - Google Patents

Description

The present invention is an input power estimation system that estimates the input power input to the rotating body from the contact surface with which the rotating body abuts, based on the vibration detection result of the vibration detecting unit installed on the rotating body such as wheels and tires. The present invention relates to an input power estimation method, a contact surface state determination system, and a mobile device control system.

Conventionally, as a system that utilizes the vibration detection result of the vibration detection unit installed on the rotating body, for example, a system for determining a road surface condition disclosed in Patent Document 1 is known. In this system, the road surface on which the tire is traveling is based on the time-varying waveform of the output value (vibration detection result) of the acceleration sensor (vibration detection unit) installed on the inner liner unit on the inner surface side of the tread portion of the tire (rotating body). Judge the state of.

Specifically, the output value of the accelerometer is acquired as the vibration input to the tire, the vibration waveform for one rotation of the tire is extracted from the time-series waveform of this vibration, and the stepping area and the kicking area are extracted from the extracted waveform. Further extract the data in the two regions of. After that, the time-series waveforms of each extracted region are frequency-analyzed, the vibration level Vf in a predetermined frequency band (8 to 10 kHz) is calculated from the obtained frequency spectrum of the stepping region, and the frequency of the obtained kicking region is calculated. The vibration level Vk in a predetermined frequency band (1 to 3 kHz) is calculated from the spectrum. Then, the calculated value S = Vf / Vk, which is an index value of the road surface condition, is calculated, and the road surface condition is determined by examining which of the predetermined calculated values Sr of the various road surfaces the calculated value S is close to. do.

Japanese Unexamined Patent Publication No. 2015-168362

In the conventional system disclosed in Patent Document 1, the output value (vibration detection result) of the acceleration sensor (vibration detection unit) installed on the inner liner portion on the inner surface side of the tread portion of the tire (rotating body) is set to the road surface (this). The road surface condition is determined by regarding it as the vibration (input power) input to the tire from the contact surface). However, the output value (vibration detection result) of the acceleration sensor (vibration detection unit) is not necessarily a parameter that accurately indicates the vibration input from the road surface to the tire. That is, the vibration detection result detected by the acceleration sensor of the conventional system is that the vibration input from the road surface to the tire propagates to the inner wall surface side of the tread portion. In this propagation process, the vibration characteristics usually change in the propagation path from the outer wall surface to the inner wall surface of the tread portion (damping of vibration level, change of frequency characteristics, etc.). Further, the vibration input from the road surface to the tire does not propagate to the inner wall surface side of the tread portion, but propagates in the tire circumferential direction or propagates to the tire sidewall portion. Therefore, the output value of the acceleration sensor installed on the tire cannot be said to be a parameter that accurately indicates the vibration input from the road surface to the tire.

The present invention has been made in view of the above background, and an object thereof is an input power estimation system and an input power estimation method capable of estimating the input power input from the contact surface to the rotating body, and the present invention. It is to provide a contact state determination system and a mobile device control system.

In order to achieve the above object, the invention of claim 1 is an input power estimation system that estimates the input power input to the rotating body from the contact surface with which the rotating body abuts, and is a specific location in the rotating body. An input unit into which the vibration detection result of the vibration detection unit for detecting the vibration of the above is input, a storage unit for storing power propagation loss for an element to which at least one is assigned to each different portion of the propagation characteristics of the rotating body, and a storage unit. The element energy of the element is calculated based on the vibration detection result input to the input unit, and the calculated element energy and the power propagation loss stored in the storage unit are input to the rotating body from the contact surface. It is characterized by having a calculation unit for calculating an estimated value of the input power.
In the present invention, at least one element is assigned to each different part of the propagation characteristics of the rotating body, and the element energy E for the element is calculated based on the detection result of the vibration detection unit. Then, the estimated value of the input power Pin input from the contact surface to the rotating body is calculated from the calculated element energy E and the power propagation loss L for the element stored _in the storage means.
Specifically, the calculation formula for calculating the estimated value of the input power Pin is as shown _in the following formula (1) when the assigned element is one. Since it is not necessary to consider the power propagation between the elements, the power propagation loss L at this time can be expressed by the internal loss rate ILF of the element. When the number of assigned elements is 2 or more, it can be represented by a matrix as shown in the following equation (1'). Since it is necessary to consider the power propagation between the elements, the power propagation loss L at this time can be expressed by the internal loss rate ILF and the coupling loss rate CLF. Note that "ω" is the central angle frequency of the bandwidth Δω of the element energy E, and [] is a symbol representing a matrix.
P _in = ω × L × E ・ ・ ・ (1)
[ _Pin ] = ω × [L] × [E] ・ ・ ・ (1')
Here, the power propagation loss L stored in the storage unit can be grasped in advance by an experiment or the like. For example, by inputting a known input power to a rotating body and calculating the element energy E from the detection result of the vibration detection unit at that time, the power propagation loss is obtained from the calculated element energy E and the known input power. L can be derived.
The input power estimated by the present invention can be used for determination processing and the like for various determination targets such as the state of the contact surface. At this time, if the "force" input from the contact surface to the rotating body can be estimated, the estimated "force" can be used for the determination process or the like in the same manner as the input power. However, in order to directly detect the "force" input from the contact surface to the rotating body, it is usually necessary to insert a sensor between the contact surface and the rotating body to detect it, and in practice, it is necessary to detect it. It is very difficult to realize. That is, the present invention is difficult to realize by detecting the "force" by estimating the "power" input from the contact surface to the rotating body instead of the "force" input from the contact surface to the rotating body. This is to easily realize the determination process and the like.

Further, the invention of claim 2 is the input power estimation system according to claim 1, wherein only one of the elements is assigned to each of the parts.
The rotating body has a rotationally symmetric shape like a tire or a wheel, and the shape of each portion having different propagation characteristics (hereinafter referred to as “rotating body portion”) is also often rotationally symmetric. In this case, even if two or more elements are assigned to each rotating body portion, the obtained vibration detection results are substantially the same or similar, although the phases are out of phase. It is possible to maintain the estimation accuracy of the input power even if the number of elements for each rotating body portion is only one. Rather, since the number of elements for each rotating body portion is limited to one, the estimated value of the input power can be calculated more easily.

The invention of claim 3 is the input power estimation system according to claim 1 or 2, wherein the rotating body is a tire, and the portion includes at least a tread portion and a sidewall portion of the tire. It is characterized by that.
According to the present invention, since the input power from the road surface to the tire can be estimated, various tests on a moving body such as an automobile or a motorcycle that moves (runs) by rotating (rolling) the tire on the road surface. , Evaluation, control, etc.

The invention of claim 4 is the input power estimation system according to any one of claims 1 to 3, wherein the rotating body is a hollow body, and the vibration detecting unit is of the rotating body. It is characterized by being installed on the hollow inner wall surface.
In the configuration in which the vibration detection unit is arranged on the outer wall surface of the rotating body, the vibration detection unit may be damaged or broken due to contact with the contact surface or other obstacles. Further, the wiring of the vibration detection unit is often pulled out to the rotation axis of the rotating body, but it is difficult to wire the vibration detection unit in the configuration where the vibration detection unit is arranged on the outer wall surface of the rotating body. According to the present invention, since the vibration detection unit is installed on the hollow inner wall surface of the rotating body, contact with the contact surface or other obstacles is avoided, and damage or failure of the vibration detection unit is suppressed. Also, wiring is easy.

Further, the invention of claim 5 is an input power estimation method for estimating the input power input to the rotating body from the contact surface with which the rotating body abuts, and is a vibration for detecting vibration at a specific position in the rotating body. Based on the input process for inputting the vibration detection result of the detection unit and the vibration detection result input in the input process, the element energy of the element to which at least one is assigned to each different part of the propagation characteristics in the rotating body is calculated. It has a calculation step of calculating an estimated value of input power input from the contact surface to the rotating body from the element energy calculated in the calculation step and the power propagation loss of the element. It is a feature.
In the present invention, at least one element is assigned to each different part of the propagation characteristics of the rotating body, and the element energy E for the element is calculated based on the detection result of the vibration detection unit. Then, the estimated value of the input power Pin input from the contact surface to the rotating body is calculated from the calculated element energy E and the power propagation loss L for the element stored _in the storage means.
Specifically, the calculation formula for calculating the estimated value of the input power Pin is as shown _in the following formula (1) when the assigned element is one. Since it is not necessary to consider the power propagation between the elements, the power propagation loss L at this time can be expressed by the internal loss rate ILF of the element. When the number of assigned elements is 2 or more, it can be represented by a matrix as shown in the following equation (1'). Since it is necessary to consider the power propagation between the elements, the power propagation loss L at this time can be expressed by the internal loss rate ILF and the coupling loss rate CLF. Note that "ω" is the central angle frequency of the bandwidth Δω of the element energy E, and [] is a symbol representing a matrix.
P _in = ω × L × E ・ ・ ・ (1)
[ _Pin ] = ω × [L] × [E] ・ ・ ・ (1')
Here, the power propagation loss L stored in the storage unit can be grasped in advance by an experiment or the like. For example, by inputting a known input power to a rotating body and calculating the element energy E from the detection result of the vibration detection unit at that time, the power propagation loss is obtained from the calculated element energy E and the known input power. L can be derived.

The invention according to claim 6 is a contact surface state determination system for determining the state of the contact surface to which the rotating body abuts, and is the input power estimation system according to any one of claims 1 to 4. It is characterized by having a determination unit for determining the state of the contact surface based on the estimated value of the input power calculated by the input power estimation system.
If the state of the contact surface is different, the input power input from the contact surface to the rotating body will be different. That is, in the case of the same rotating body, there is a high correlation between the input power input from the contact surface to the rotating body and the state of the contact surface. Therefore, according to the present invention, the state of the contact surface can be determined using the estimated value of the input power calculated by the input power estimation system.

The invention of claim 7 is a mobile device control system for controlling a predetermined device mounted on a moving body that moves by rotating the rotating body on the contact surface, according to claims 1 to 4. It is characterized by having the input power estimation system according to any one of the above, and a control unit that controls the predetermined device based on the estimated value of the input power calculated by the input power estimation system. be.
As described above, it is possible to determine the state of the contact surface and the characteristics of the rotating body from the input power input from the contact surface to the rotating body. Therefore, according to the present invention, it is possible to control the device mounted on the moving body according to the state of the contact surface and the characteristics of the rotating body.

According to the present invention, there is an excellent effect that the input power input to the rotating body from the contact surface can be estimated.

The schematic diagram which shows the outline of the input power estimation system in embodiment. A block diagram showing an SEA model consisting of two elements. (A) is an explanatory diagram showing an example in which a tire is divided into four elements. (B) is a block diagram showing a model composed of four elements. The graph which shows the experimental result when the input power was calculated using the input power estimation system of an embodiment by changing the number of elements. The graph which shows a part (for one rotation of a tire) of the output waveform of the 1st acceleration sensor at the time of a tire rolling. A graph comparing the input power input from the road surface to the tire in each section of the stepping section (Leading edge), the ground contact section (Contact patch), and the kicking section (Trailing edge). (A) is a graph when the estimated value of the input power of the stepping section (Leading edge) is calculated under various conditions. (B) is a graph when the estimated value of the input power of the contact patch is calculated under various conditions. The flowchart which shows an example of the road surface condition determination system (contact surface condition determination system) of embodiment.

Hereinafter, the input power estimation system according to the present invention is input to a tire as a rolling element, which is a rotating body provided _in an automobile as a moving body, from a road surface as a rolling surface which is a contact surface. An embodiment applied to an input power estimation system for a tire for estimating a tire will be described.

_In this embodiment, an example of estimating the input power Pin to the tire of an automobile will be described, but if the input power input to the rotating body is estimated from the contact surface with which the rotating body abuts. good. Therefore, for example, the rotation of a wheel or the like provided in another moving body that can be moved by rotating (rolling) the rotating body (rolling body) on the contact surface (rolling surface) such as a train or an airplane. Input power input from the surface (contact surface) of the object to be machined to a rotating body such as a mill, a drill, or a rotary blade used when estimating the input power to the body or during cutting or cutting. The present invention can be applied in various situations such as when estimating.

The input power estimation system of the present embodiment uses a statistical energy analysis ( _SEA ) to estimate the input power pin input to the tire. In the SEA analysis procedure of the present embodiment, at least one element is assigned to each different part of the propagation characteristics in the tire, and the internal loss factor (ILF) for each element and the coupling loss rate (Coupling Loss) between the elements are assigned. Factor: CLF) is obtained and an energy propagation model consisting of the relevant elements is constructed. Then, the element energy E of each element is derived from the vibration detection result of the specific portion _in the tire, and the element energy E is applied to the model to calculate the estimated value of the input power Pin.

FIG. 2 is a block diagram showing an SEA model composed of two elements.
In FIG. 2, P ₁ and P ₂ are input powers input to each element 1 and 2, P ₁₂ is power propagating from element 1 to element 2, and P ₂₁ is propagating from element 2 to element 1. P _d1 and P _d2 are the powers dissipated in each element, and E ₁ and E ₂ are the energies of each element. In this model, the following equations (2) and (3) hold.
P ₁ = P _d1 + P ₁₂ -P ₂₁ ... (2)
P ₂ = P _d2 + P ₂₁ -P ₁₂ ... (3)

In order to generalize this, if the code i for identifying the elements (1 or 2 indicating the number of each element in the model of FIG. 2) is used, the power P _di dissipated by the element i is the element i. It can be obtained from the following equation (4) from the element energy E _i , the central angular frequency ω of the bandwidth Δω of the element energy E _i , and η _i which is the internal loss rate ILF of the element i.
P _di = ω × η _i × E _i・ ・ ・ (4)

Further, when the symbols i and j for identifying the elements are used, the power _Pij propagating from the element i to the element j is the element energy E _i of the element i and the central angular frequency ω of the bandwidth Δω of the element energy E _i . , Can be obtained from the following equation (5) from η _ij , which is the bond loss rate CLF from the element i to the element j.
P _ij = ω × η _ij × E _i・ ・ ・ (5)

Summarizing the above, the input power pin input to the model can be obtained by the following matrix (6) by replacing the internal loss rate _ILF and the coupling loss rate CLF with the power propagation loss L.
[ _Pin ] = ω × [L] × [E] ・ ・ ・ (6)

The matrix (6) is shown in the following matrix (7), for example, when applied to a three-element division example excluding the element 4 out of the four elements as shown in FIG. 3 described later.

FIG. 3A is an explanatory diagram showing an example in which the tire in the present embodiment is divided into four elements 1 to 4, and FIG. 3B is a block showing a model composed of the four elements 1 to 4. It is a figure.
In this four-element division example, the tire is divided by 90 °, and in consideration of the symmetry of the tire, as shown in FIG. 3A, a total of two elements for the sidewall portion 4 and two elements for the tread portion 2. Four elements are assigned.

As shown _in FIG. 3, when the input power Pin to the tire is obtained by SEA by dividing into four elements, first, the vibration generated at a specific place in the tire is detected, and each element 1 to 4 is detected from the vibration detection result. The elemental energies E ₁ , E ₂ , E ₃ , and E ₄ of are derived. The element energies E ₁ , E ₂ , E ₃ , and E ₄ are derived by, for example, installing a vibration detection unit such as an acceleration sensor at the tire location corresponding to each element and applying the sensor output value to an energy conversion formula. ..

When a 3-axis accelerometer is used, the element energy E _i of the element i can be derived from the following energy conversion equation (8). Note that "Vx", "Vy", and "Vz" are velocities in the x-direction, y-direction, and z-direction orthogonal to each other, and each is obtained from the output value of the acceleration sensor. Further, "mi" is the mass of the tire portion corresponding to the element _i .
E _i = 1/2 x _mi x (Vx ² + Vy ² + Vz ² ) ... (8)

Next, the estimated value of the input power _Pin is calculated by applying the derived element energies E ₁ , E ₂ , E ₃ , and E ₄ to the above-mentioned matrix (6). At this time, it is necessary to acquire the power propagation loss L (internal loss rate ILF, coupling loss rate CLF) in advance. For the power propagation loss L, for example, a known input power _P'in is input to the tire, an element energy E is calculated from the vibration detection result at that time, and the calculated element energy E and the known input power P are calculated. 'It can be derived from _in .

FIG. 1 is a schematic diagram showing an outline of the input power estimation system according to the present embodiment.
The input power estimation system 10 of the present embodiment estimates the input power _pin to the tire, and is mainly composed of a sensor input unit 11, a storage unit 12, a calculation unit 13, and an output unit 14. Has been done.

The tire 1 used in the present embodiment is a general tubeless tire, and as shown in FIG. 1, mainly includes a tread portion 2, a shoulder portion 3, a sidewall portion 4, and a bead portion 5. Has been done. The tire 1 has a basic structure in which the carcass 6, which is the frame of the tire, is covered with a rubber layer, and the inner liner 7 is attached to the inner surface of the tire. Further, the tread portion 2 is provided with a reinforcing belt 2a for increasing the rigidity of the tread, and the bead portion 5 is provided with a bead wire 5a and is attached to the wheel 9.

The tire 1 can be roughly divided into a tread portion 2 and a sidewall portion 4 when the tire 1 is divided into parts having different propagation characteristics. Therefore, in the present embodiment, at least one element is assigned to each of the tread portion 2 and the sidewall portion 4. At this time, the number of elements to be assigned to each of the tread section 2 and the sidewall section 4 can be arbitrarily set, but in the present embodiment, the tread section 2 and the sidewall section 2 and the sidewall section 2 and the sidewall section 4 can be estimated more easily _in order to estimate the input power pin more easily. One element is assigned to each part 4. Considering the symmetry when the tire is rolling, it is possible to obtain sufficient accuracy by allocating one element to each of the tread portion 2 and the sidewall portion 4.

FIG. 4 is a graph showing experimental results when the number of elements is changed and the input power is calculated using the input power estimation system of the present embodiment.
In this graph, the input power is on the vertical axis and the frequency is on the horizontal axis. In this experiment, an example of two-element division in which one element is assigned to each of the tread portion 2 and the sidewall portion 4, and four elements in which two elements are assigned to each of the tread portion 2 and the sidewall portion 4 are assigned. An example of division was compared with an example of 6-element division in which three elements were assigned to each of the tread portion 2 and the sidewall portion 4. As shown in FIG. 4, all the element division examples are almost the same.

Therefore, in the present embodiment, the first acceleration sensor 21 is installed at one location (center position in the tire width direction) on the inner wall surface of the tread portion 2 of the tire 1, and on the inner wall surface of the sidewall portion 4 of the tire 1. The second acceleration sensor 22 is installed at one location (the same tire circumferential position as the first acceleration sensor 21). As a result, the element energy ET of one element (hereinafter referred to as “element _T ”) assigned to the tread unit 2 is acquired from the output value (vibration detection result) of the first acceleration sensor 21, and the second acceleration sensor 22 The element energy ES of one element (hereinafter referred to as “element _S ”) assigned to the sidewall portion 4 can be acquired from the output value (vibration detection result) of.

The number of accelerometers installed does not have to match the number of assigned elements. That is, the element energy E of one element may be acquired from the output value of two or more acceleration sensors, or the element energy E of two or more elements may be acquired from the output value of one acceleration sensor.

The sensor input unit 11 in the input power estimation system 10 of the present embodiment receives the input of the output values of the two acceleration sensors 21 and 22 installed on the tire 1. In the present embodiment, the first acceleration sensor 21 includes vibration (in-plane vibration) in the tire circumferential direction x and the direction y orthogonal to the tire circumferential direction x at the installation position (specific location) on the inner wall surface of the tread portion 2 of the tire 1. It is a 3-axis accelerometer that detects vibration in the direction z perpendicular to the inner wall surface (out-of-plane vibration). Further, the second acceleration sensor 22 includes vibration (in-plane vibration) in the tire circumferential direction x and the direction y orthogonal to the tire circumferential direction x at the installation position (specific location) on the inner wall surface of the sidewall portion 4 of the tire 1 and the inner wall surface. It is a 3-axis accelerometer that detects vibration in the direction z perpendicular to (out-of-plane vibration).

In the present embodiment, the three-axis accelerometers 21 and 22 are used as the vibration detection unit, but other accelerometers such as the one-axis accelerometer can also be used. Further, other sensors such as a speed sensor and a displacement sensor can be used as long as they can detect the vibration for guiding the element energies ET and ES of each element _T and _S. In the present embodiment, it is an example of the power propagation loss considering both the out-of-plane vibration and the in-plane vibration, but it is possible to obtain sufficient accuracy even with the out-of-plane vibration alone.

Further, in the embodiment, since the tire 1 is a hollow body, the acceleration sensors 21 and 22 can be installed on the hollow inner wall surface of the tire 1. Since it can be installed on the hollow inner wall surface of the tire 1, it is not necessary to arrange the acceleration sensor on the outer wall surface of the tire 1. In the configuration in which the acceleration sensor is arranged on the outer wall surface of the tire 1, the acceleration sensor may be damaged or broken due to contact with the road surface 100 or other obstacles (steps on the road surface, road surface installation objects, etc.). On the other hand, in the configuration in which the acceleration sensor is arranged on the inner wall surface of the tire 1 as in the present embodiment, it is possible to avoid such damage or failure of the acceleration sensor.

Further, when the acceleration sensors 21 and 22 and the sensor input unit 11 are connected by wire, the wiring is often pulled out to the rotation shaft of the tire 1. At this time, in the configuration in which the acceleration sensor is arranged on the outer wall surface of the tire 1, it is necessary to pull the wiring from the outer wall surface of the tire 1 to the inner wall surface side and pull it out to the rotation axis, which makes the wiring difficult. On the other hand, in the configuration in which the acceleration sensor is arranged on the inner wall surface of the tire 1 as in the present embodiment, it is not necessary to draw the wiring from the outer wall surface of the tire 1 to the inner wall surface side, so that the wiring is easy.

The storage unit 12 stores the power propagation loss L (internal loss rate ILF and coupling loss rate CLF) for the two elements T and S described above. The power propagation loss L stored in the storage unit 12 can be acquired in advance by an experiment or the like. Specifically, as described above, the known input power _P'in is input to the tire 1, and the element energy E is calculated from the output values (vibration detection results) of the acceleration sensors 21 and 22 at that time. The power propagation loss L is derived from the calculated element energy E and the known input power _P'in .

The calculation unit 13 calculates the element energies ET and ES for the two elements _T and _S based on the detection results of the acceleration sensors 21 and 22, and stores them in the calculated element energies _ET and _ES and the storage unit 12. From the power propagation loss _L , the estimated value of the input power Pin input from the road surface 100 to the tire 1 is calculated.

The element energy ET of the element _T of the tread portion 2 is derived from the above equation (8) from the output value (vibration detection result) of the first acceleration sensor 21 installed on the inner wall surface of the tread portion 2. Similarly, the element energy ES of the element _S of the sidewall portion 4 is derived from the above equation (8) from the output value (vibration detection result) of the second acceleration sensor 22 installed on the inner wall surface of the sidewall portion 4. do. Further, the calculation of the estimated value of the input power _Pin is performed using the above equation (6). The power propagation loss L is used by calling what is stored in the storage unit 12.

The output unit 14 _outputs the estimated value of the input power pin calculated by the calculation unit 13 to the determination unit 30. The input power estimation system 10 of the present embodiment may be used only for obtaining an estimated value of the input power pin, but _in the present embodiment, the estimation of the input power _pin output from the output unit 14 is estimated. The value is output to the determination unit 30 in the same system or in another system, and is used for the determination process in the determination unit 30.

The determination unit 30 receives an estimated value of the input power _pin output from the output unit 14 of the input power _estimation system 10, and performs a determination process for a predetermined determination target based on the estimated value of the input power pin. do. The hardware of the determination unit 30 can be mainly composed of a computer device including a CPU, ROM, RAM, communication I / F, data I / F, and the like. In this case, the CPU executes various processes and controls including the determination process by executing various programs stored in the ROM. The ROM stores various programs for the CPU to execute various processes and controls. The RAM is used as a work area for the CPU. The communication I / F communicates with the input power estimation system 10 and _receives an estimated value of the input power pin output from the output unit 14 of the input power estimation system 10. In addition, when the determination result is output to another system or information from another system is acquired, communication with the other system is also performed. For example, communication is performed with various in-vehicle sensors such as a navigation device, a GPS device, and a vehicle speed sensor of the vehicle, and a travel control system of the vehicle via the CAN (Controller Area Network) of the vehicle equipped with the tire 1.

The estimated value of the input power _Pin input from the road surface 100 to the tire 1 can be used for determination of various types of determination targets such as the state of the road surface 100.
FIG. 5 is a graph showing a part of the output waveform (for one rotation of the tire) of the first acceleration sensor 21 when the tire 1 is rolled.
In this graph, the output value of the out-of-plane vibration (z direction) among the output values of the first acceleration sensor 21 is taken on the vertical axis, and the time is taken on the horizontal axis. The input power from the road surface to the tire is the section of the tire that is in contact with the road surface, the section where the tire starts to contact the road surface (stepping edge: Leading edge) and the section where the tire continues to contact the road surface (ground contact section: Contact). It can be divided into a patch) and a section where the tire starts to move away from the road surface (kicking section: Trailing edge).

FIG. 6 is a graph comparing the input power input from the road surface 100 to the tire 1 in each section of the stepping section (Leading edge), the ground contact section (Contact patch), and the kicking section (Trailing edge). ..
In this graph, the input power is on the vertical axis and the frequency is on the horizontal axis. As shown in this graph, the magnitude relationship of the input power between the sections is the relationship of the ground contact section (Contact patch)> the kicking section (Trailing edge)> the stepping section (Leading edge).

FIG. 7A is a graph when the estimated value of the input power of the stepping section (Leading edge) is calculated under various conditions.
FIG. 7B is a graph when the estimated value of the input power of the contact patch is calculated under various conditions.
In the graph of FIG. 7, the condition 1 when the tire 1 in a state where the vehicle speed is 40 [km / h] and the load is 4 [kN] is rolled on the road surface 100 in the road surface condition “normal” is satisfied. Condition 2 when the tire 1 with a load of 4 [kN] applied at a vehicle speed of 100 [km / h] is rolled on the road surface 100 of the road surface condition "normal", and the vehicle speed of 40 [km]. Condition 3 when the tire 1 with a load of 1 [kN] applied at [/ h] is rolled on the road surface 100 of the road surface condition "normal", and a load at a vehicle speed of 40 [km / h]. This is a comparison with the condition 4 when the tire 1 with 4 [kN] applied is rolled on the road surface 100 in the road surface condition "Smooth".

As shown in FIG. 7B, the input power of the contact patch includes condition 1 in which the road surface condition is "normal" and condition 4 in which the road surface condition is "smooth". Then, they are almost the same. On the other hand, as shown in FIG. 7A, the input power of the stepping section (Leading edge) has a “smooth” road surface condition rather than the condition 1 in which the road surface condition is “normal”. Condition 4 is a significantly smaller value. Therefore, it is possible to determine the slipperiness of the road surface condition from the input power of the stepping section (Leading edge).

FIG. 8 is a flowchart showing an example of the road surface condition determination system (contact surface condition determination system) according to the present embodiment.
_In the main road surface condition determination system, the determination unit 30 first receives the input of the estimated value of the input power pin output from the output unit 14 of the input power estimation system 10 described above (S1). Then, the estimated value of the input power of the portion corresponding to the stepping section (Leading edge) is extracted from the estimated value of the input input power _Pin (S2).

Then, the input power estimated value of the extracted stepping section (Leading edge) is compared with a predetermined threshold value of 1 or 2 or more (S3). This threshold value can be obtained in advance by an experiment or the like according to the number of types of road surface conditions to be determined. Then, the road surface condition (for example, the slipperiness level of the road surface) is determined according to the result of comparison with this threshold value (S4).

In the conventional system disclosed in Patent Document 1, the road surface condition can be determined by grasping in advance the correlation between the output value of the acceleration sensor installed on the inner liner portion on the inner surface side of the tread portion of the tire and the road surface condition. It is what you do. This correlation changes depending on the type of tire (vibration propagation characteristics, etc.). Therefore, in this conventional system, it is necessary to grasp the correlation between the output value of the acceleration sensor and the road surface condition for each type of tire. Specifically, it is necessary to perform a running test on each tire on each road surface having a different road surface condition and acquire the characteristics of the output value of the acceleration sensor according to the road surface condition.

On the other hand, as in the present embodiment, the system for determining the road surface condition from the estimated value of the input power from the road surface to the tire grasps the correlation between the estimated value of the input power and the road surface condition in advance, and thereby the road surface. It determines the state. According to this system, the correlation between the estimated input power and the road surface condition does not change even if the type of tire changes. Therefore, once the correlation is grasped, it is not necessary to perform complicated work such as grasping the correlation for each type of tire.

This merit is also a merit obtained in other systems that judge from the estimated value of the input power from the road surface to the tire for the judgment target other than the road surface condition.

According to the main road surface condition determination system, it is possible to individually determine the road surface condition of the road surface 100 on which the tire is in contact with each tire of the automobile. This determination result can be used for various driving controls such as a traction control system, an anti-lock braking system, and an automatic attitude control mounted on an automobile.

Further, according to the main road surface condition determination system, it is possible to grasp the degree of deterioration of the road surface by performing comparison using the input power estimated value in the normal road surface condition as a threshold value. For example, by continuously acquiring the judgment result of the road surface condition in association with the position information of the GPS device while driving the car, the data of which position of the road surface is deteriorated (how much is deteriorated) is acquired. It is possible. Such data can be effectively used, for example, for road surface repair plans.

Further, in this road surface condition determination system, the power propagation loss L for directly calculating the estimated value of the input power from the outer wall surface of the tread portion of the tire 1 in contact with the road surface is used, but this is limited to this. I can't. For example, an estimated value of input power may be calculated using an unfinished tire such as a tire before the tread portion 2 is attached or a smooth tire before the tread pattern is formed on the tread portion 2. Even in this case, if the relationship between the estimated value of the input power of the unfinished tire and the estimated value of the input power of the finished product is known, the input power from the road surface of the finished tire should be estimated. Can be done.

1 Tire 2 Tread part 2a Reinforcing belt 3 Shoulder part 4 Sidewall part 5 Bead part 5a Bead wire 6 Carcass 7 Inner liner 9 Wheel 10 Input power estimation system 11 Sensor input unit 12 Storage unit 13 Calculation unit 14 Output unit 21 First acceleration Sensor 22 Second acceleration sensor 30 Judgment unit 100 Road surface ILF Internal loss rate _CLF Coupling loss rate L Power propagation loss E Element energy Pin Input power

Claims (7)

It is an input power estimation system that estimates the input power input to the rotating body from the contact surface with which the rotating body abuts.
An input unit into which the vibration detection result of the vibration detection unit that detects vibration at a specific location in the rotating body is input, and an input unit.
A storage unit that stores the power propagation loss for an element to which at least one is assigned to each different portion of the propagation characteristics of the rotating body.
The element energy of the element is calculated based on the vibration detection result input to the input unit, and the calculated element energy and the power propagation loss stored in the storage unit are input to the rotating body from the contact surface. An input power estimation system characterized by having a calculation unit for calculating an estimated value of input power. The input power estimation system according to claim 1.
An input power estimation system, characterized in that only one element is assigned to each part. The input power estimation system according to claim 1 or 2.
The rotating body is a tire and
The portion is an input power estimation system comprising at least a tread portion and a sidewall portion of the tire. The input power estimation system according to any one of claims 1 to 3.
The rotating body is a hollow body and has a hollow body.
The vibration detection unit is an input power estimation system characterized in that it is installed on a hollow inner wall surface of the rotating body. It is an input power estimation method that estimates the input power input to the rotating body from the contact surface with which the rotating body abuts.
An input process for inputting a vibration detection result of a vibration detection unit that detects vibration at a specific location in the rotating body, and an input step.
Based on the vibration detection result input in the input step, a calculation step of calculating the element energy of an element to which at least one is assigned to each different portion of the propagation characteristics in the rotating body, and a calculation step.
The input power is characterized by having a calculation step of calculating an estimated value of the input power input from the contact surface to the rotating body from the element energy calculated in the calculation step and the power propagation loss for the element. Estimating method. It is a contact surface condition determination system that determines the condition of the contact surface with which the rotating body abuts.
The input power estimation system according to any one of claims 1 to 4.
A contact surface state determination system comprising a determination unit for determining a state of the contact surface based on an estimated value of input power calculated by the input power estimation system. A mobile device control system that controls a predetermined device mounted on a moving body that moves by rotating the rotating body on the contact surface.
The input power estimation system according to any one of claims 1 to 4.
A mobile device control system comprising a control unit that controls the predetermined device based on an estimated value of the input power calculated by the input power estimation system.

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