Friction coefficient calculation device

Abstract

To provide a friction coefficient calculation device capable of accurately estimating the maximum friction coefficient. [Solution] The friction coefficient calculation device comprises a calculation unit that calculates the slip ratio and the calculated friction coefficient; a storage unit that stores the calculated slip ratio information and the calculated friction coefficient information in storage quantities; a model calculation unit that sets multiple model maximum friction coefficients and model maximum slip ratios, calculates multiple model friction coefficients, and determines the model error for each of the multiple brush model characteristics; an accuracy determination unit that determines whether the model maximum friction coefficient is a high-accuracy maximum friction coefficient; a maximum friction coefficient estimation unit that extracts the estimated maximum friction coefficient; an upper and lower limit extraction unit that extracts the upper limit maximum friction coefficient and the lower limit maximum friction coefficient; and an output determination unit that determines whether to output the estimated maximum friction coefficient to the outside. The output determination unit does not output the estimated maximum friction coefficient to the outside if it does not determine that the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to a predetermined determination friction range.

Description

Technical Field

[0001] The present disclosure relates to a friction coefficient calculation device.

Background Art

[0002] Conventionally, there is known a friction state estimation device that calculates the slip ratio of a wheel and the driving / braking force of the wheel, estimates the friction state of the road surface based on the calculated slip ratio and driving / braking force, and controls the driving / braking of the vehicle so that the wheel does not slip (see, for example, Patent Document 1). This friction state estimation device obtains the ratio of the change amount of the slip ratio to the change amount of the driving / braking force a plurality of times, and obtains a plurality of tangents to the tire characteristic curve showing the relationship between the slip ratio and the driving / braking force obtained from a general tire model based on the plurality of obtained ratios. Then, it estimates the slip ratio at which the driving / braking force in the tire characteristic curve becomes the maximum value, and controls the driving / braking force so that the driving / braking force does not exceed the maximum value based on the estimated slip ratio.

[0003] In the tire characteristic curve, the driving / braking force gradually increases as the slip ratio increases from a state where the slip ratio is zero, and gradually decreases as the slip ratio increases beyond the slip ratio at which the driving / braking force becomes the maximum. Therefore, the slip ratio when the driving / braking force changes from an increasing state to a decreasing state is the slip ratio at which the driving / braking force becomes the maximum.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when controlling the braking and driving forces of a vehicle, information on the road surface friction coefficient is required in addition to the slip ratio, and in particular, information on the maximum friction coefficient just before the tires begin to slip is important. For this reason, friction coefficient calculation devices that estimate the maximum value of the road surface friction coefficient are required to estimate the maximum value of the friction coefficient with high accuracy. Furthermore, the road surface friction coefficient has a correlation with the slip ratio. Therefore, the maximum value of the friction coefficient can be calculated based on the slip ratio at which the braking and driving forces are maximized.

[0006] However, while the slip ratio and braking force can be calculated based on information obtained from various sensors such as torque sensors and vehicle speed sensors installed on the vehicle, errors may be present in these calculated slip ratios and braking forces. Furthermore, if the slip ratio that maximizes the braking force is estimated based on the slip ratio and braking force that contain errors, the estimated slip ratio will also contain errors.

[0007] Therefore, the method described in Patent Document 1 makes it difficult to accurately calculate the maximum value of the friction coefficient. In particular, when multiple tangents to the tire characteristic curve are determined using slip ratios that are within a relatively small range, such as 0.1 or less or 0.2 or less, if there is variation in the error included in the calculated slip ratio, the variation in the tangents to be determined tends to increase. When the slip ratio at which the braking and driving force is maximized is estimated from multiple tangents with such large variations, the error in the estimated slip ratio increases, and as a result, the error in the maximum value of the maximum friction coefficient calculated using the slip ratio also increases.

[0008] In view of the above points, this disclosure aims to provide a friction coefficient calculation device capable of accurately estimating the maximum friction coefficient. [Means for solving the problem]

[0009] According to one perspective of this disclosure, A friction coefficient calculation device estimates the maximum friction coefficient, which is the maximum value of the friction coefficient between the tire and the road surface, based on detection signals transmitted from a detection unit that detects information about the tire when the vehicle is traveling on the road surface. A calculation unit that calculates the calculated slip ratio, which is the slip ratio between the tire and the road surface, and the calculated friction coefficient, which is the friction coefficient between the tire and the road surface, based on the detection signal. The calculation unit links the calculated slip ratio information and the calculated friction coefficient information, and the storage unit stores only the set number of these values. A model calculation unit obtains multiple brush model characteristics based on a tire brush model that simulates the physical phenomena between a tire and the road surface by setting multiple maximum model friction coefficients, which are the maximum values ​​of the friction coefficient in the brush model equation, and multiple maximum model slip ratios, which are the maximum values ​​of the slip ratio in the brush model equation. The unit calculates multiple model friction coefficients, which are theoretical estimates of the friction coefficient, using the brush model equations based on the set multiple maximum model friction coefficients and multiple maximum model slip ratios, and the calculated slip ratios of the stored quantities stored in the storage unit. The unit then calculates the model error, which is information regarding the error between the calculated multiple model friction coefficients and the calculated friction coefficients of the stored quantities stored in the storage unit, for each of the multiple brush model characteristics. Based on the model error calculated by the model calculation unit, the accuracy determination unit determines whether each of the multiple maximum friction coefficients set by the model calculation unit is a high-accuracy maximum friction coefficient that is likely to correspond to the maximum friction coefficient. A maximum friction coefficient estimation unit extracts an estimated maximum friction coefficient, which is an estimated value of the maximum friction coefficient, from among the model maximum friction coefficients that have been determined to be the highest-accuracy maximum friction coefficients. An upper and lower limit extraction unit extracts an upper limit maximum friction coefficient, which is the upper limit of the estimated maximum friction coefficient, and a lower limit maximum friction coefficient, which is the lower limit of the estimated maximum friction coefficient, based on the model error. It includes an output determination unit that determines whether or not to output the estimated maximum friction coefficient to the outside based on the upper limit maximum friction coefficient and the lower limit maximum friction coefficient, The output determination unit does not output the estimated maximum friction coefficient externally if it determines that the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to a predetermined determination friction range. If it determines that the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to the determination friction range, it outputs the estimated maximum friction coefficient externally.

[0010] According to this, the output determination unit does not output the estimated maximum friction coefficient if the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to the determined friction range. Therefore, it is possible to avoid outputting the estimated maximum friction coefficient when there is a risk that the estimated maximum friction coefficient will deviate from the maximum friction coefficient due to variations in the calculated slip ratio or calculated friction coefficient with respect to the brush model characteristics. Consequently, it is possible to avoid outputting an estimated maximum friction coefficient that may have poor accuracy, and only an estimated maximum friction coefficient that has been accurately determined can be output, thus enabling accurate estimation of the maximum friction coefficient.

[0011] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of a control device that functions as a friction coefficient calculation device according to the first embodiment. [Figure 2] This figure shows the brush model characteristics illustrating the correlation between the coefficient of friction and the slip ratio. [Figure 3] This figure shows multiple brush model characteristics based on the maximum model slip ratio and maximum model friction coefficient acquired by the model calculation unit according to the first embodiment. [Figure 4] This flowchart shows an example of a control process performed by the control device according to the first embodiment. [Figure 5] This is an explanatory diagram illustrating the method for calculating model errors. [Figure 6] This figure shows the model error for each maximum slip ratio of the model. [Figure 7] This contour plot shows the set of model errors for each brush model characteristic. [Figure 8] This flowchart shows an example of a control process performed by the control device according to the second embodiment. [Figure 9] This figure shows multiple brush model characteristics based on the maximum model slip ratio and maximum model friction coefficient acquired by the model calculation unit according to the second embodiment. [Figure 10] This flowchart shows an example of a control process performed by the control device according to the third embodiment. [Figure 11] This is an explanatory diagram illustrating how to set the judgment threshold set by the model calculation unit according to the third embodiment. [Figure 12] This flowchart shows an example of a control process performed by the control device according to the fourth embodiment. [Figure 13] This is an explanatory diagram illustrating the process of extracting the high-accuracy maximum friction coefficient performed by the control device according to the fourth embodiment. [Figure 14] This is a schematic diagram of a control device that functions as a friction coefficient calculation device according to the fifth embodiment. [Figure 15] This flowchart shows an example of a control process performed by the control device according to the fifth embodiment. [Figure 16] This is a time chart illustrating the storage process performed by the storage unit according to the fifth embodiment. [Figure 17] This figure shows the calculated slip ratio and model friction coefficient before the storage quantity is increased. [Figure 18] This figure shows the calculated slip ratio and model friction coefficient after the storage unit has increased the storage quantity. [Figure 19] This is a schematic diagram of a control device that functions as a friction coefficient calculation device according to the sixth embodiment. [Figure 20] This flowchart shows an example of a control process performed by the control device according to the sixth embodiment. [Figure 21] This is a time chart illustrating the storage process performed by the storage unit according to the sixth embodiment. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination.

[0014] (First Embodiment) This embodiment will be described with reference to Figures 1 to 7. The friction coefficient calculation device of this embodiment is used, for example, in a vehicle control system that controls the movement of an electric vehicle, and is a device that estimates the maximum friction coefficient μp, which is the maximum value of the friction coefficient between the tire and the road surface. The vehicle control system is, for example, for controlling the rotational speed of a motor to drive a vehicle. As shown in Figure 1, the vehicle control system has a detection unit S that detects various information related to the behavior of the vehicle and a control device 1 that controls the rotational speed of the motor based on the information detected by the detection unit S. This control device 1 is called an ECU and also functions as the friction coefficient calculation device of this embodiment. ECU is an abbreviation for Electronic Control Unit.

[0015] The detection unit S is a group of sensors installed in the vehicle that detect various information related to the vehicle's behavior, particularly information related to the tires when the vehicle is traveling on the road. Specifically, the detection unit S includes a vehicle speed sensor for detecting the vehicle's speed, a wheel speed sensor for detecting the rotational speed of the tires, a steering angle sensor for detecting the rotation angle of the steering wheel, a yaw rate sensor for detecting the rotational angular velocity of the vehicle in the yaw direction, and an acceleration sensor for detecting the vehicle's acceleration. Furthermore, the detection unit S includes a torque sensor for detecting the magnitude of the torque applied to the tires and a load sensor for detecting the load generated on the tires. The detection unit S transmits a detection signal to the control device 1 each time it detects a detection value corresponding to a detection value repeatedly detected by these various sensors at predetermined control cycles.

[0016] The control device 1 consists of a microcomputer and its peripheral circuits, which include a CPU, ROM, and RAM. The memory is composed of a non-transitional physical storage medium. The control device 1 performs various calculations and processes based on the program stored in the ROM. As shown in Figure 1, the control device 1 has a calculation unit 10, a storage unit 20, a model calculation unit 30, an accuracy determination unit 40, a maximum friction coefficient estimation unit 50, an upper and lower limit extraction unit 60, and an output determination unit 70.

[0017] When the control device 1 receives a detection signal from the detection unit S corresponding to the detection values ​​detected by various sensors, it executes a program stored in ROM and functions as a calculation unit 10, a storage unit 20, a model calculation unit 30, an accuracy determination unit 40, a maximum friction coefficient estimation unit 50, an upper and lower limit extraction unit 60, and an output determination unit 70. Alternatively, the control device 1 may have multiple circuit modules that correspond one-to-one with the calculation unit 10, storage unit 20, model calculation unit 30, accuracy determination unit 40, maximum friction coefficient estimation unit 50, upper and lower limit extraction unit 60, and output determination unit 70.

[0018] The following will describe each of the following units individually: the calculation unit 10, the storage unit 20, the model calculation unit 30, the accuracy determination unit 40, the maximum friction coefficient estimation unit 50, the upper and lower limit extraction unit 60, and the output determination unit 70. First, the calculation unit 10 will be described. The calculation unit 10 is a calculation device that calculates the slip ratio and the friction coefficient between the tires and the road surface when a vehicle is traveling on the road surface, based on various detection signals transmitted from the detection unit S. The calculation unit 10 includes a slip ratio calculation unit 11 that calculates the slip ratio and a friction coefficient calculation unit 12 that calculates the friction coefficient.

[0019] The slip ratio calculation unit 11 is a calculation device that calculates the slip ratio between the tire and the road surface based on detection signals input from the detection unit S corresponding to detection values ​​detected by various sensors. For example, when a vehicle is moving straight, the slip ratio calculation unit 11 calculates the slip ratio based on the difference between the vehicle speed detected by the vehicle speed sensor and the tire rotation speed detected by the wheel speed sensor. Also, when a vehicle is skidding, for example, the slip ratio calculation unit 11 calculates the slip ratio based on the detection values ​​detected by the steering angle sensor, yaw rate sensor, and acceleration sensor in addition to the detection values ​​detected by the vehicle speed sensor and wheel speed sensor. The slip ratio calculation unit 11 has a storage unit 20 connected to its output side. The slip ratio calculation unit 11 calculates the slip ratio for each detection signal repeatedly acquired from the detection unit S at predetermined control cycles and transmits the calculated slip ratio to the slip ratio storage unit 21 of the storage unit 20, which will be described later. The slip ratio calculated by the slip ratio calculation unit 11 is calculated slip ratio s c It is also called [another name].

[0020] When a detection signal corresponding to the detection values detected by various sensors is input from the detection unit S to the friction coefficient calculation unit 12, the friction coefficient calculation unit 12 is an arithmetic device that calculates the friction coefficient of the road surface based on these detection values. The friction coefficient calculation unit 12 calculates the friction coefficient based on, for example, the detection values detected by a torque sensor, a load sensor, and an acceleration sensor. The friction coefficient calculation unit 12 has a storage unit 20 connected to the output side. Then, the friction coefficient calculation unit 12 calculates the friction coefficient for each detection signal repeatedly acquired from the detection unit S at a predetermined control cycle, and transmits the calculated slip ratio to a friction coefficient storage unit 22 (described later) of the storage unit 20. Hereinafter, the friction coefficient calculated by the friction coefficient calculation unit 12 is referred to as the calculated friction coefficient μ c is also called.

[0021] Although not shown, a noise filter may be provided between the arithmetic unit 10 and the storage unit 20. This noise filter is composed of, for example, a low-pass filter or the like, and when noise caused by vehicle vibration or the like is included in the calculated slip ratio s c and the calculated friction coefficient μ c the noise is removed.

[0022] The storage unit 20 is a storage unit that stores the calculated slip ratio s c obtained from the slip ratio calculation unit 11 and the calculated friction coefficient μ c obtained from the friction coefficient calculation unit 12. The storage unit 20 has a slip ratio storage unit 21 that stores the calculated slip ratio s c and a friction coefficient storage unit 22 that stores the calculated friction coefficient μ c The storage unit 20 is composed of, for example, a FIFO memory that can retrieve the stored information in the order in which it was stored. Note that FIFO is an abbreviation for First In First Out.

[0023] The slip ratio storage unit 21 stores the information of the calculated slip ratio s c repeatedly calculated by the slip ratio calculation unit 11 for each control cycle by a predetermined predetermined storage quantity, and can overwrite and store new information with respect to the stored information. The slip ratio storage unit 21 repeatedly acquires the calculated slip ratio s from the slip ratio calculation unit 11c The information is stored in predetermined quantities.

[0024] The friction coefficient storage unit 22 stores the calculated friction coefficient μ, which is repeatedly calculated by the friction coefficient calculation unit 12 at each control cycle. c It saves information and allows new information to be overwritten on the saved information. In addition, the friction coefficient storage unit 22 stores the slip ratio s calculated by the slip ratio storage unit 21. c The friction coefficient μ is calculated using the same number of stored quantities as the information to be stored. c The friction coefficient storage unit 22 can store the calculated friction coefficient μ, which is repeatedly obtained from the friction coefficient calculation unit 12. c The information is stored in predetermined quantities.

[0025] The storage unit 20 stores the calculated slip ratio s that the slip ratio calculation unit 11 repeatedly calculates at each control cycle. c The friction coefficient calculation unit 12 repeatedly calculates the calculated friction coefficient μ at each control cycle. c These pieces of information are linked and stored. The storage unit 20 then stores the calculated slip rate s that is linked to it. c Information and calculation of friction coefficient μ c The information is stored in a predetermined quantity. The storage unit 20 has a model calculation unit 30 connected to its output side. The storage unit 20 stores the calculated slip rate s that is associated with it. c Information and calculation of friction coefficient μ c The information is transmitted to the model calculation unit 30 for each predetermined storage quantity.

[0026] For example, the slip ratio storage unit 21 stores N calculated slip ratios s c The information can be stored, and the friction coefficient storage unit 22 stores N calculated friction coefficients μ c It is assumed that the information can be saved. In this case, the storage unit 20 stores the calculated slip rate s associated with each of them. c Information and calculation of friction coefficient μ c The information is sent to the model calculation unit 30 in units of N. The following are the N calculated slip rates s output by the storage unit 20. c The slip ratio group s calculates the information.c [0:N] is written, and the storage unit 20 outputs N calculated friction coefficients μ c The friction coefficient group μ is calculated using the information. c [0:N] is written. The storage unit 20 stores the calculated slip ratio group s c [0:N] Information and calculated friction coefficient group μ c The information in the range [0:N] is sent to the model calculation unit 30. Note that N is an integer greater than or equal to 1.

[0027] The model calculation unit 30 is a calculation device that sets candidate friction coefficient values ​​for the maximum friction coefficient μp calculated by the friction coefficient calculation device, based on a tire brush model that simulates physical phenomena in the contact area between the tire and the road surface, and obtains information about the set candidate values. As information about the candidate values, the model calculation unit 30 obtains the model friction coefficient μ, which is a theoretical estimate of the friction coefficient using the brush model equation based on the tire brush model, as information about the candidate values. md In addition to calculating the model friction coefficient μ, md The calculated friction coefficient μ stored in the storage unit 20 c The difference is calculated. Then, the information of the set candidate values ​​and the model friction coefficient μ md The coefficient of friction μ is calculated. c Information regarding the difference between the two values ​​will be output. First, let's explain the brush model equation shown in Equation 1 below.

[0028] [Mathematics 1] μ md =(HK 2 s 3 -3HKs 2 -3Hs) / Fd In Equation 1, H is a parameter of the brush model equation and is calculated using Equation 2 below. In Equation 1, K is a parameter of the brush model equation and is calculated using Equation 3 below. In Equation 1, s represents the slip ratio between the tire and the road surface. In Equation 1, Fd represents the driving force generated in the tire and can be detected by the load sensor of the detection unit S.

[0029] [Math 2] H=μp md / spmd

[0030] [Math 3] K=1 / sp md μp in Equation 2 md This represents the maximum friction coefficient of the model, which is the maximum friction coefficient of the brush model equation. Also, in equations 1 and 2, sp md This represents the maximum slip ratio of the brush model equation, which is the maximum slip ratio of the model. In Equation 1, H is the maximum friction coefficient of the model μp, as shown in Equation 2. md and the maximum slip ratio of the model sp md It can be calculated based on the following. In Equation 1, K is the maximum slip rate of the model sp, as shown in Equation 3. md It can be calculated based on this. Therefore, the brush model equation shown in Equation 1 is the model maximum friction coefficient μp md and the maximum slip ratio of the model sp md It is based on.

[0031] The model friction coefficient μ is calculated using the brush model equation shown above. md The model friction coefficient μ is correlated with the slip ratio, and its value changes in accordance with changes in the slip ratio. For example, the model friction coefficient μ when a vehicle is accelerating. md As shown in Figure 2, the slip ratio increases cubically as the tire rotation speed increases. Below, the model friction coefficient μ is as shown in Figure 2. md A model friction coefficient μ that shows the correlation with the slip ratio. md These characteristics are referred to as brush model characteristics.

[0032] Here, as shown in the brush model characteristics, the model friction coefficient μ md When a vehicle starts moving from a standstill, the slip ratio increases in the region where the tires do not slip. However, the model friction coefficient μ with respect to the increase in slip ratio mdThe rate of increase gradually decreases as the slip ratio increases. Then, as the slip ratio increases to a predetermined value by increasing the rotational speed of the tire until just before the tire begins to spin, the model friction coefficient μ increases in proportion to the amount of the slip ratio. md The slip ratio stops increasing. In other words, when the slip ratio increases to this predetermined value, the model friction coefficient μ md The amount of change with increasing slip ratio is approximately zero. The slip ratio just before the tire starts to slip is the maximum slip ratio in the tire brush model, which is the maximum slip ratio sp in the region where the tire does not slip. md The maximum slip ratio of the model is sp. md The model friction coefficient μ at the above slip ratios md This is the model friction coefficient μ when the tire is spinning freely. md That is the case.

[0033] Therefore, the model friction coefficient μ md From equations 1 to 3, the slip ratio and the model maximum friction coefficient μp are obtained. md And, the maximum slip ratio of the model sp md It can be calculated based on the following. Also, the maximum slip ratio of the model, sp md and the maximum friction coefficient of the model μp md By setting the maximum slip ratio sp of the model in advance to various arbitrary values, md and the maximum friction coefficient of the model μp md Various brush model characteristics can be obtained.

[0034] For example, the maximum slip ratio sp of the model. md The minimum value of the setting is set to 0, and the setting is increased by 0.01 from the minimum value, and the maximum friction coefficient of the model μp md Let's set the minimum value to 0 and increase the setting value by 0.1 from the minimum value. In this case, the maximum slip ratio of the model, sp, will change by 0.01 each time. md The maximum friction coefficient μp of the model is changed in increments of 0.1 from the set value. mdEach combination of the setting value yields different brush model characteristics as shown in Figure 3. Note that the square in Figure 3 represents the set maximum model slip ratio sp. md Setting values ​​and model maximum friction coefficient μp md This shows the combination with the setting values.

[0035] The model calculation unit 30 calculates the maximum slip ratio sp of the model in this manner. md and the maximum friction coefficient of the model μp md By setting this to an arbitrary value in advance, multiple brush model characteristics can be obtained. Furthermore, the model calculation unit 30 sets the maximum model friction coefficient μp to obtain multiple brush model characteristics. md This is stored as a candidate value for the maximum friction coefficient μp. The model calculation unit 30 of this embodiment calculates the model maximum slip ratio sp over the entire range from the minimum to the maximum value that the slip ratio can take. md In addition to setting the maximum friction coefficient μp for the model across the entire range from the minimum to the maximum value it can take. md Set the parameters to obtain multiple brush model characteristics.

[0036] Specifically, the model calculation unit 30 calculates the maximum slip ratio of the model, sp. md The minimum value is set to 0 and the maximum value is set to 1, and the maximum friction coefficient of the model μp md The minimum value is set to 0 and the maximum value is set to 1. Then, the model calculation unit 30 calculates the model maximum slip ratio sp md The maximum friction coefficient of the model, μp, is increased by 0.01 in the range from a minimum value of 0 to a maximum value of 1. md Multiple brush model characteristics are obtained by increasing the value by 0.1 increments within the range from a minimum value of 0 to a maximum value of 1.

[0037] As a result, the model calculation unit 30 calculates the maximum slip ratio sp of the model. md Increase the value from 0 to 1.00 in increments of 0.01, and set the maximum friction coefficient of the model μp mdVarious combinations of brush model characteristics that can be obtained by incrementing [a parameter] from 0 to 1.0 in increments of 0.1 are stored. Then, in the model calculation unit 30, as candidate values for the maximum friction coefficient μp, 11 model maximum friction coefficients μp set by incrementing from 0 to 1.0 in increments of 0.1 are stored. md The information of md is stored as candidate values for the maximum friction coefficient μp.

[0038] Note that for the model maximum slip ratio sp for obtaining the brush model characteristics, md if the set value is any value within the range from 0 to 1, it may be changed in increments smaller than 0.01 or in increments larger than 0.01. Also, for the model maximum friction coefficient μp for obtaining the brush model characteristics, md if the set value is any value within the range from 0 to 1, it may be changed in increments smaller than 0.1 or in increments larger than 0.1.

[0039] Then, the model calculation unit 30 uses the plurality of stored brush model characteristics to obtain information regarding the error between the calculated friction coefficient μ c and the model friction coefficient μ of each brush model characteristic. The model calculation unit 30 is connected to the accuracy determination unit 40 on the output side. Then, the model calculation unit 30 transmits information regarding the error between the model friction coefficient μ md calculated for each brush model characteristic and the calculated friction coefficient μ md and information on the candidate values of the set maximum friction coefficient μp to the accuracy determination unit 40. The candidate values of the maximum friction coefficient μp are the information of the set values of the model maximum friction coefficient μp c set for obtaining the brush model characteristics. The details of how to obtain the information regarding the error between the calculated friction coefficient μ md and the model friction coefficient μ of each brush model characteristic will be described later. c md md For each brush model characteristic, the accuracy determination unit 40 acquires the model friction coefficient μ

[0040] from the model calculation unit 30 and the calculated friction coefficient μ md cBased on the information regarding the error, the model maximum friction coefficient μp was set as a candidate value for the maximum friction coefficient μp. md The accuracy is determined by the model maximum friction coefficient μp set in the model calculation unit 30. md In contrast, the maximum slip ratio of the model is sp md For each case, it is determined whether or not it is possible to reach the maximum friction coefficient μp. The accuracy determination unit 40 of this embodiment determines the 11 maximum model friction coefficients μp set to obtain the brush model characteristics. md For each case, it is determined whether or not it has the potential to be the maximum friction coefficient μp. Below are the model maximum friction coefficients μp that the accuracy determination unit 40 has determined to have the potential to be the maximum friction coefficient μp. md The high-accuracy maximum friction coefficient μp jud It is called that.

[0041] The accuracy determination unit 40 has a maximum friction coefficient estimation unit 50 and an upper / lower limit extraction unit 60 connected to its output side. The accuracy determination unit 40 then determines the high-accuracy maximum friction coefficient μp jud The information is transmitted to the maximum friction coefficient estimation unit 50 and the upper and lower limit extraction unit 60, respectively. The accuracy determination unit 40 determines the high-accuracy maximum friction coefficient μp jud Details on how to make this determination will be described later.

[0042] The maximum friction coefficient estimation unit 50 determines the high-accuracy maximum friction coefficient μp by the accuracy determination unit 40. jud The model's maximum friction coefficient μp was determined to be... md This method estimates the maximum friction coefficient μp from among the following. The maximum friction coefficient estimation unit 50 of this embodiment estimates the model friction coefficient μ calculated for each brush model characteristic. md The coefficient of friction μ is calculated. c Based on the information regarding the error, the accuracy determination unit 40 determines the high-accuracy maximum friction coefficient μp jud From among these, one maximum friction coefficient μp is estimated. Below, the maximum friction coefficient μp estimated by the maximum friction coefficient estimation unit 50 is referred to as the estimated maximum friction coefficient μp. est The maximum friction coefficient estimation unit 50 is connected to the output determination unit 70. The maximum friction coefficient estimation unit 50 then determines the estimated maximum friction coefficient μpest The information is transmitted to the output determination unit 70. The maximum friction coefficient estimation unit 50 estimates the maximum friction coefficient μp est Details of the estimation method will be described later.

[0043] The upper and lower limit extraction unit 60 extracts the estimated maximum friction coefficient μp extracted by the maximum friction coefficient estimation unit 50. est The output determination unit 70 obtains information used to determine whether or not to output the estimated maximum friction coefficient μp to the outside. The upper and lower limit extraction unit 60 obtains information used by the output determination unit 70 to determine whether or not to output the estimated maximum friction coefficient μp est The information used to determine whether or not to output the estimated maximum friction coefficient μp is est The upper and lower limits of the range that can be taken are extracted. The upper and lower limit extraction unit 60 of this embodiment calculates the friction coefficient μ c and the model friction coefficient μ of each brush model characteristic md The high-accuracy maximum friction coefficient μp is determined based on information regarding the error. jud Estimated maximum coefficient of friction μp est Extract the upper and lower limits of the range that it can take.

[0044] Below, estimated maximum friction coefficient μp est Of the range that can be taken, the upper limit value extracted by the upper and lower limit extraction unit 60 is the upper limit maximum friction coefficient μp max It is called [this]. Also, the estimated maximum coefficient of friction μp est Of the range that can be taken, the lower limit value extracted by the upper and lower limit extraction unit 60 is the lower limit maximum friction coefficient μp min This is referred to as the upper and lower limit extraction unit 60. The output determination unit 70 is connected to the output side. The upper and lower limit extraction unit 60 then extracts the upper maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min Each piece of information is transmitted to the output determination unit 70. The upper and lower limit extraction unit 60 performs the upper limit maximum friction coefficient μp. max and lower limit of maximum friction coefficient μp min Details of each extraction process will be described later.

[0045] The output determination unit 70 obtains the estimated maximum friction coefficient μp from the maximum friction coefficient estimation unit 50. estThis determines whether or not to output the information to the outside. The output determination unit 70 obtains the upper limit maximum friction coefficient μp from the upper limit lower limit extraction unit 60. max Information and lower limit of maximum friction coefficient μp min Based on the information, the estimated maximum coefficient of friction μp est The output determination unit 70 determines whether or not to output the information to the outside. The output determination unit 70 obtains the estimated maximum friction coefficient μp from the maximum friction coefficient estimation unit 50. est When it is determined that the information of the estimated maximum friction coefficient μp should be output externally, est The maximum friction coefficient μp is output externally. In response, the output determination unit 70 obtains the estimated maximum friction coefficient μp from the maximum friction coefficient estimation unit 50. est If it is not determined that the information will be output externally, then the estimated maximum friction coefficient μp est The maximum friction coefficient μp is not output externally.

[0046] Next, an example of a specific control process performed by the control device 1 will be explained with reference to the flowchart shown in Figure 4. The control device 1, consisting of a calculation unit 10, a storage unit 20, a model calculation unit 30, an accuracy determination unit 40, a maximum friction coefficient estimation unit 50, an upper and lower limit extraction unit 60, and an output determination unit 70, repeatedly executes each of the control processes shown in Figure 4 at predetermined control cycles to estimate the maximum friction coefficient μp est The control device 1, comprising the calculation unit 10, storage unit 20, model calculation unit 30, accuracy determination unit 40, maximum friction coefficient estimation unit 50, upper and lower limit extraction unit 60, and output determination unit 70, repeatedly executes the process shown in Figure 4 at predetermined control cycles in order to calculate the maximum friction coefficient μp. The processes executed by each of the calculation unit 10, storage unit 20, model calculation unit 30, accuracy determination unit 40, maximum friction coefficient estimation unit 50, upper and lower limit extraction unit 60, and output determination unit 70 will be described below. Note that the processes executed by each of the calculation unit 10, storage unit 20, model calculation unit 30, accuracy determination unit 40, maximum friction coefficient estimation unit 50, upper and lower limit extraction unit 60, and output determination unit 70 may also be described collectively as processes executed by the control device 1.

[0047] The control device 1 has a configuration as a microcomputer, including a CPU, RAM, ROM, and non-volatile rewritable memory (not shown). The control device 1 reads and executes a computer program stored in the ROM or non-volatile rewritable memory, which are non-transitional physical storage media. When this computer program is executed, the method corresponding to the computer program is performed. In other words, the control device 1 performs various control processes, such as the control process shown in Figure 4, according to the computer program.

[0048] First, in step S10, the calculation unit 10 calculates the slip ratio s based on the detection signal transmitted from the detection unit S. c and calculated friction coefficient μ c The slip ratio calculation unit 11 calculates the slip ratio s based on, for example, the detection signals transmitted from the vehicle speed sensor and the wheel speed sensor. c The friction coefficient calculation unit 12 calculates the friction coefficient μ based on detection signals transmitted from, for example, a torque sensor, a load sensor, and an acceleration sensor. c The calculation unit 10 calculates the slip ratio s at predetermined control cycles. c and calculated friction coefficient μ c The calculated slip rate s is calculated. c Information and calculation of friction coefficient μ c The information is output to the storage unit 20.

[0049] In the subsequent step S20, the storage unit 20 stores the calculated slip rate s obtained from the calculation unit 10. c Information and calculation of friction coefficient μ c The slip ratio storage unit 21 stores the calculated slip ratio s obtained from the slip ratio calculation unit 11 at predetermined control cycle intervals. c The information is stored for a quantity of N items. In addition, the friction coefficient storage unit 22 stores the calculated friction coefficient μ obtained from the friction coefficient calculation unit 12 at predetermined control cycles. c The information is stored for a maximum of N items. The storage unit 20 stores the calculated slip ratio s obtained from the slip ratio calculation unit 11. cInformation and the calculated friction coefficient μ obtained from the friction coefficient calculation unit 12 c The information is linked and saved. Then, the storage unit 20 stores the N calculated slip rates s that have been stored. c The information and the N calculated friction coefficients μ that were saved. c The information and the calculated slip ratio group s c [0:N] Information and calculated friction coefficient group μ c The information [0:N] is transmitted to the model calculation unit 30. The storage unit 20 stores N calculated slip rates s. c Information and N calculated friction coefficients μ c When this information is sent to the model calculation unit 30, the process proceeds to step S30.

[0050] The control device 1 repeatedly executes the processes from step S30 to step S90 to obtain various brush model characteristics, thereby obtaining the maximum model slip ratio sp md and the maximum friction coefficient of the model μp md Multiple settings are configured, and the brush model characteristics are acquired for each. Then, the control device 1 calculates the model friction coefficient μ of the brush model characteristics based on the acquired brush model characteristics. md The coefficient of friction μ is calculated. c We obtain information regarding the error and set the maximum friction coefficient μp for each model. md High accuracy maximum friction coefficient μp jud Determine whether or not it is true.

[0051] Specifically, in step S30, the first step executed among the repeatedly performed steps S30 to S90, the model calculation unit 30 calculates the maximum slip ratio of the model sp md The minimum value of the set value, μp, is set to 0. Also, in the first step S40, the model calculation unit 30 calculates the maximum friction coefficient of the model μp md The maximum slip ratio sp of the model is set to 0, which is the minimum value of the set value. md Information and the set maximum friction coefficient μp of the model md It stores information about that.

[0052] Then, in step S50, the model calculation unit 30 calculates the set maximum model slip ratio sp md and the maximum friction coefficient of the model μp md Based on the above-mentioned equations 2 and 3, the parameters H and K of the brush model equation are calculated. H and K are the parameters of the brush model equation shown in equation 1.

[0053] In the following step S60, the model calculation unit 30 calculates the maximum slip ratio of the model sp md Model maximum friction coefficient μp md Based on the parameters, the set maximum slip rate sp of the model md and the maximum friction coefficient of the model μp md The brush model characteristics are obtained. Then, the model calculation unit 30 uses the brush model equation shown in Equation 1 to calculate the slip ratio group s stored in the storage unit 20. c The calculated slip rate s of the N stored quantities included in [0:N] c Model friction coefficient μ in each case md Calculate.

[0054] In the following step S70, the model calculation unit 30 calculates the friction coefficient μ c and the calculated model friction coefficient μ in the brush model characteristics md Information regarding the error is sought. The model calculation unit 30 of this embodiment calculates the friction coefficient μ c and the model friction coefficient μ md The error is calculated as the model error Err using the following formula 4.

[0055] [Math 4] Err=Σ((μ md -μ c ) 2 ) As shown in the above equation 4 and Figure 5, the model calculation unit 30 calculates the N model friction coefficients μ md Each of them, and the model friction coefficient μ md Each calculated slip ratio s used to calculate the slip ratio c Each calculated friction coefficient μ linked toc The error is calculated. This gives N model friction coefficients μ md Each of them, and the calculated slip ratio group s c [0:N] Calculated friction coefficient group μ c The N calculated friction coefficients μ included in [0:N] c The error for each can be calculated. Note that the circles in Figure 5 represent the N calculated slip rates s. c and calculated friction coefficient μ c N model friction coefficients μ calculated from md This indicates that.

[0056] Then, the model calculation unit 30 calculates the N model friction coefficients μ md Each of these, and the corresponding N calculated friction coefficients μ c The sum of the errors with each is calculated as the model error Err. The model calculation unit 30 sets the maximum model slip ratio sp to obtain the brush model characteristics. md Information and model maximum friction coefficient μp md The information and the calculated model error Err are transmitted to the accuracy determination unit 40. In this way, the model calculation unit 30 sets the maximum model slip ratio sp to obtain the brush model characteristics. md and the maximum friction coefficient μp md The model error Err information corresponding to the combination is transmitted to the accuracy determination unit 40.

[0057] The accuracy determination unit 40 determines the maximum slip rate sp of the model obtained from the model calculation unit 30. md Information and model maximum friction coefficient μp md The system stores the information and the model error Err. Then, in step S80, the accuracy determination unit 40 determines the maximum model friction coefficient μp set to obtain the brush model characteristics based on the acquired model error Err. md The system determines whether there is a high probability that the model error Err obtained from the model calculation unit 30 corresponds to the maximum friction coefficient μp. Specifically, the accuracy determination unit 40 determines whether the model error Err obtained from the model calculation unit 30 corresponds to a predetermined determination threshold Err. _th Determine whether it is smaller or not. Judgment threshold: Err _th The maximum friction coefficient of the model is μpmd A predetermined threshold is set in advance to determine whether or not it is highly likely to be the maximum coefficient of friction μp, and can be set, for example, by conducting an experiment in advance on a road surface where the maximum coefficient of friction μp is known.

[0058] Model error Err is the decision threshold Err _th If it is not determined to be smaller, the accuracy determination unit 40 skips the process in step S90 and returns to the process in step S40. In contrast, the model error Err is determined to be less than the determination threshold Err _th If it is determined to be smaller, in step S90, the accuracy determination unit 40 determines the maximum model friction coefficient μp set to obtain the brush model characteristics. md The most likely to correspond to the maximum coefficient of friction μp is the maximum coefficient of friction μp. jud It is stored as follows. Also, the model error Err is the decision threshold Err _th If it is determined to be smaller, the accuracy determination unit 40 determines the determination threshold Err _th This smaller model error Err is the small model error Err jud It is stored as follows: Model error Err is the decision threshold Err _th If it is smaller, the accuracy determination unit 40 determines the maximum slip ratio sp of the model set in step S30. md The information and the high-accuracy maximum friction coefficient μp set in step S40. jud The information and the small model error Err determined in step S. jud This information is linked and stored. Then, after processing in step S90, the process returns to processing in step S40.

[0059] Returning to the process in step S40, the model calculation unit 30 calculates the maximum slip ratio of the model sp md While maintaining the setting value, the maximum friction coefficient of the model μp set in the previous control process md The value obtained by adding 0.1 to this is the maximum friction coefficient of the model, μp. md It is set as follows. Then, the model calculation unit 30 calculates the set maximum model slip ratio sp md Information and the set maximum friction coefficient μp of the model md It stores information about that.

[0060] By repeating the processes from steps S50 to S70, the model calculation unit 30 calculates the maximum slip ratio of the model sp md Set to 0, and the maximum friction coefficient of the model μp md The model error Err information corresponding to the combination in which is set to 0.1 is transmitted to the accuracy determination unit 40. Then, in step S80, the accuracy determination unit 40 determines that the model error Err obtained again from the model calculation unit 30 is the determination threshold Err. _th Determine whether it is smaller or smaller. The model error Err is the threshold for determination Err. _th If it is determined to be smaller, in step S90, the accuracy determination unit 40 determines the set maximum friction coefficient of the model μp md High-accuracy maximum friction coefficient μp jud It is stored as a small model error Err. jud Remember it as such.

[0061] The control device 1 controls the model maximum friction coefficient μp md The maximum friction coefficient of the model μp until its value becomes 1.0 md The process from step S40 to step S90 is repeated by adding 0.1 to the value. The control device 1 sets the maximum slip ratio sp of the model. md and the maximum friction coefficient μp md The model error Err corresponding to each combination is calculated, and the set maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud The control device 1 then determines whether or not the set maximum friction coefficient μp md High accuracy maximum friction coefficient μp jud In this case, this high-accuracy maximum friction coefficient μp jud In addition to storing the model error Err, the model error Err is reduced to a smaller model error Err. jud Remember it as such.

[0062] Furthermore, the control device 1 controls the maximum slip ratio sp of the model. md With this set to 0, the maximum friction coefficient of the model μp mdThe process is increased to 1.0, and steps S40 to S90 are executed, after which the process returns to step S30.

[0063] Returning to the process in step S30, the model calculation unit 30 calculates the maximum slip ratio of the model sp md The maximum slip ratio sp of the model set in the previous control process. md The value is set by adding 0.01 to it. Also, in step S40, the model calculation unit 30 calculates the maximum friction coefficient of the model μp md Set to 0. Then, the model calculation unit 30 calculates the set maximum model slip ratio sp md Information and the set maximum friction coefficient μp of the model md It stores information about that.

[0064] By repeating the processes from steps S50 to S70, the model calculation unit 30 calculates the maximum slip ratio of the model sp md Set to 0.01, and the maximum friction coefficient of the model μp md The model error Err corresponding to the combination in which is set to 0 is transmitted to the accuracy determination unit 40. Then, in step S70, the model calculation unit 30 calculates the set maximum model slip ratio sp md and the maximum friction coefficient μp md The model error Err corresponding to the combination is calculated. Based on the model error Err, the accuracy determination unit 40 determines the set maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud The accuracy determination unit 40 then determines whether or not it is true. md High accuracy maximum friction coefficient μp jud In this case, this high-accuracy maximum friction coefficient μp jud In addition to storing the model error Err, the model error Err is reduced to a smaller model error Err. jud Remember it as such.

[0065] The control device 1 controls the model maximum friction coefficient μp md The maximum friction coefficient of the model μp until its value becomes 1.0 mdThe process from step S40 to step S90 is repeated by adding 0.1 to the value. As a result, the accuracy determination unit 40 determines the maximum slip ratio sp of the model, as shown in Figure 6. md Small model error Err when set to 0.01 jud The information provides highly accurate maximum friction coefficient μp jud This information is stored in association with the relevant data. Note that the white circles in Figure 6 represent the judgment threshold Err. _th This shows a smaller model error Err, and the black circles in Figure 6 represent the decision threshold Err. _th The above shows the model error Err. The control device 1 then controls the maximum slip ratio sp of the model. md Set to 0.01, and the maximum friction coefficient of the model μp md After increasing to 1.0, the process of step S90 is executed, and then the process returns to step S30.

[0066] Thus, the control device 1 controls the maximum slip ratio sp of the model. md Each increase of 0.01 reduces the model's maximum friction coefficient μp. md The maximum friction coefficient of the model μp until its value becomes 1.0 md The process from step S50 to step S90 is repeated by adding 0.1 to the value. Furthermore, the control device 1 determines the maximum slip ratio of the model sp md Model maximum slip rate sp until it reaches 1.00 md The process from step S50 to step S90 is repeated, increasing the value by 0.01 each time.

[0067] Then, the control device 1 sets the maximum slip ratio sp for each model. md and the maximum friction coefficient μp for each model md The control device 1 calculates the model error Err corresponding to each combination for each brush model characteristic. Then, the control device 1 calculates the set maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud The control device 1 determines whether or not it is the set maximum friction coefficient μp md High accuracy maximum friction coefficient μp jud In this case, this high-accuracy maximum friction coefficient μp judIn addition to memorizing this, this high-accuracy maximum friction coefficient μp jud The model error Err associated with the small model error Err jud Remember it as such.

[0068] By repeatedly executing the processes from step S30 to step S90, the model calculation unit 30 calculates the maximum slip ratio of the model sp md While changing it by 0.01, the maximum friction coefficient of the model μp md The brush model characteristics of various patterns are obtained by changing the value by 0.1 increments. Then, the model calculation unit 30 calculates the model error Err for each obtained brush model characteristic, thereby calculating the friction coefficient μ c and the model friction coefficient μ in the brush model characteristics md Information regarding the error is sought. Then, the accuracy determination unit 40 determines the set maximum model friction coefficient μp based on the model error Err obtained from each brush model characteristic of each pattern. md High accuracy maximum friction coefficient μp jud Determine whether or not it is true.

[0069] This allows you to obtain the brush model characteristics of each pattern by setting the maximum friction coefficient μp for each model. md Among them, the judgment threshold Err _th Model maximum friction coefficient μp corresponding to a smaller model error Err md High accuracy maximum friction coefficient μp jud It is stored as such. Also, the high-accuracy maximum friction coefficient μp jud The corresponding model error Err is small model error Err jud It will be remembered as such.

[0070] The accuracy determination unit 40, for example as shown in Figure 6, sets the maximum model slip ratio sp to acquire the brush model characteristics. md Each, high-accuracy maximum friction coefficient μp jud and small model error Err judThe information is linked and stored. The accuracy determination unit 40 performs the processing in steps S30 to S90 to obtain the high-accuracy maximum friction coefficient μp for each brush model characteristic. jud Information and small model error Err jud This information is transmitted to the maximum friction coefficient estimation unit 50 and the upper and lower limit extraction unit 60, respectively.

[0071] Then, in step S100, the storage unit 20 stores the N calculated slip rates s that have been stored. c Information and N calculated friction coefficients μ stored c The information is erased. As a result, the storage unit 20 will not be able to retrieve the newly obtained calculated slip rate s from the calculation unit 10 in processing that is performed after this control cycle. c Information and calculation of friction coefficient μ c This makes it possible to store the information. For this reason, the storage unit 20 stores the slip rate s calculated for every N items. c Information and calculation of friction coefficient μ c The information is saved.

[0072] In step S110, the upper and lower limit extraction unit 60 extracts the high-accuracy maximum friction coefficient μp based on the model error Err extracted by the accuracy determination unit 40. jud From among them, the upper limit of the maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min Specifically, the upper and lower limit extraction unit 60 extracts the high-accuracy maximum friction coefficient μp by the accuracy determination unit 40. jud The model's maximum friction coefficient μp was determined to be... md The highest value among them is the maximum high-accuracy friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max The extraction is performed as follows. Furthermore, the upper and lower limit extraction unit 60 determines the high-accuracy maximum friction coefficient μp by the accuracy determination unit 40. jud The model's maximum friction coefficient μp was determined to be... md From among them, the highest accuracy maximum friction coefficient μp with the smallest value jud Lower limit maximum coefficient of friction μp min Extracted as follows: For example, the high-accuracy maximum friction coefficient μp obtained in the repeatedly executed step S90. judIf it is within the range of 0.3 to 0.6, the upper and lower limit extraction unit 60 determines the upper limit maximum friction coefficient μp max 0.6 was extracted as the lower limit of the maximum friction coefficient μp min Extract 0.3 as the result.

[0073] The accuracy determination unit 40 extracts the high-accuracy maximum friction coefficient μp jud If there is only one, the high-accuracy maximum friction coefficient μp of that one. jud The upper limit of the maximum coefficient of friction μp max and lower limit of maximum friction coefficient μp min Extracted as follows: That is, the small model error Err is extracted by the process of step S80 which is performed repeatedly. jud The maximum model friction coefficient μp corresponds to the model error Err which is determined to be the model error. md If there is only one value, the upper limit of the maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min These all represent the small model error Err jud High-accuracy maximum friction coefficient μp linked to jud This is the result.

[0074] The maximum friction coefficient estimation unit 50 performs the processing in steps S120 and S130, thereby determining the high-accuracy maximum friction coefficient μp by the accuracy determination unit 40. jud The model's maximum friction coefficient μp was determined to be... md From among them, the estimated maximum friction coefficient μp est Specifically, in step S110, the maximum friction coefficient estimation unit 50 estimates the small model error Err determined by the accuracy determination unit 40 based on the model error Err. jud Of these, the smallest model error Err has the smallest value. jud The minimum model error minErr jud The minimum model error minErr is extracted. Then, in step S130, the maximum friction coefficient estimation unit 50 calculates the extracted minimum model error minErr. jud High-accuracy maximum friction coefficient μp linked to jud Estimated maximum coefficient of friction μp est The maximum friction coefficient estimation unit 50 extracts the extracted estimated maximum friction coefficient μp. estThe information is transmitted to the output determination unit 70.

[0075] In step S140, the output determination unit 70 determines the upper limit maximum friction coefficient μp max Information and lower limit of maximum friction coefficient μp min Based on the information, the estimated maximum friction coefficient μp is obtained from the maximum friction coefficient estimation unit 50. est The system determines whether or not to output the information to the outside. Specifically, the output determination unit 70 of this embodiment determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min The difference is calculated. Then, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If it is determined that the difference is less than or equal to a predetermined friction range, in step S150, the estimated maximum friction coefficient μp est This information is output externally as the maximum friction coefficient μp.

[0076] For example, the output determination unit 70 determines the estimated maximum friction coefficient μp est This information is output to the navigation system installed in the vehicle. As a result, the navigation system receives the estimated maximum friction coefficient μp obtained from the control device 1. est The information is communicated to the occupants as the maximum friction coefficient μp. Alternatively, the control device 1 provided in the vehicle control system communicates the estimated maximum friction coefficient μp output by the output determination unit 70. est This information may be used to control the vehicle's movement.

[0077] In response, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is not determined to be below a predetermined friction range, the estimated maximum friction coefficient μp est It does not output. In this case, the control process returns to the process of step S10.

[0078] The determined friction range is determined by the estimated maximum friction coefficient μp extracted by the maximum friction coefficient estimation unit 50. estTo determine whether the estimation accuracy is high or not, a predetermined size is set, which can be determined by conducting an experiment in advance on a road surface where the maximum friction coefficient is known. est Information on the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min This explains the reason for deciding whether or not to output to an external source based on the difference between the two values.

[0079] As mentioned above, the estimated maximum coefficient of friction μp est This is a set of multiple possible model maximum friction coefficients μp to obtain brush model characteristics. md Among them, the judgment threshold Err _th Smaller model error Err jud High-accuracy maximum friction coefficient μp linked to jud And the maximum friction coefficient estimation unit 50 calculates the small model error Err jud Of these, the smallest value is the minimum model error minErr. jud High-accuracy maximum friction coefficient μp linked to jud Estimated maximum coefficient of friction μp est This is extracted as follows: The estimated maximum friction coefficient μp extracted by the maximum friction coefficient estimation unit 50 in this manner. est This is a set of multiple possible model maximum friction coefficients μp to obtain brush model characteristics. md Of these, this is the friction coefficient that is most likely to correspond to or approximate the maximum friction coefficient μp.

[0080] And the estimated maximum coefficient of friction μp est If it matches or approximates the maximum friction coefficient μp, the calculation unit 10 calculates the calculated friction coefficient μ c The estimated maximum coefficient of friction μp est Model friction coefficient μ corresponding to the brush model characteristics set. md The result will be a value that matches or approximates it. That is, the calculated friction coefficient μ c Model friction coefficient μ calculated from md The line along it represents the estimated maximum friction coefficient μp estThis will be a curve that matches or approximates the brush model characteristics corresponding to it.

[0081] However, the calculated slip rate s calculated by the calculation unit 10 c , or calculate the coefficient of friction μ c When the brush model characteristics vary due to external factors, etc., the model friction coefficient μ is determined based on the characteristics of each brush model. md The coefficient of friction μ is calculated. c There is a risk that the errors will become larger in each case. Such a model friction coefficient μ md The coefficient of friction μ is calculated. c If the error becomes large, the estimated maximum friction coefficient μp is calculated based on the brush model characteristics. est The discrepancy between the calculated friction coefficient μp and the maximum friction coefficient μp tends to increase. In particular, the calculated friction coefficient μ c , or calculate the coefficient of friction μ c When it is relatively small, such as 0.1 or less, the calculated friction coefficient μ c , or calculate the coefficient of friction μ c The effects of variations tend to be large. And the estimated maximum friction coefficient μp calculated based on the brush model characteristics. est The discrepancy between this value and the maximum friction coefficient μp tends to become large.

[0082] Here, the model friction coefficient μ is based on the characteristics of each brush model. md The coefficient of friction μ is calculated. c As the errors with each factor increase, the model error Err will vary, and the decision threshold Err will also vary. _th Smaller model error Err jud The quantity may increase. And the small model error Err jud As the quantity increases, the model error Err jud High-accuracy maximum friction coefficient μp linked to jud The quantity increases, and the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min This becomes a factor that increases the difference. In other words, the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min When the difference between the two becomes large, the estimated maximum friction coefficient μp estThere is a possibility that the maximum friction coefficient μp will differ from the upper limit of the maximum friction coefficient μp. max and the lower limit of the maximum coefficient of friction μp min When the difference is relatively large, the estimated maximum friction coefficient μp est It is preferable not to output the maximum friction coefficient μp.

[0083] In contrast, the calculated friction coefficient μ c and the model friction coefficient μ md The error is small, and the calculated slip rate s relative to the brush model characteristics is small. c , or calculate the coefficient of friction μ c When the variability of is small, the variability of the model error Err also becomes small. Therefore, the decision threshold Err _th Smaller model error Err jud The quantity does not increase easily, and the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min The difference between this and the calculated friction coefficient μ tends to be relatively small. c Model friction coefficient μ calculated from md If the line along the curve matches or approximates the brush model characteristics, then the estimated maximum friction coefficient μp corresponding to those brush model characteristics is... est This reduces the deviation from the maximum friction coefficient μp.

[0084] Therefore, the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min When the difference is relatively small, the estimated maximum friction coefficient μp est The discrepancy between the estimated maximum friction coefficient μp and the estimated maximum friction coefficient μp becomes smaller. For example, in the contour plot showing the set of model errors Err for each brush model characteristic shown in Figure 7, est However, the upper limit of the maximum friction coefficient μp is relatively narrow. max and the lower limit of the maximum coefficient of friction μp min If present between the two, the estimated maximum friction coefficient μp est It can be assumed that the deviation from the maximum friction coefficient μp is small. Note that Figure 7 is a contour plot showing the set of model errors Err for each brush model characteristic, and the judgment threshold Err _th Smaller values ​​for model error Errjud The set is shown by a straight line, and the circle represents the estimated maximum friction coefficient μp. est This indicates.

[0085] Based on the above, the control device 1 of this embodiment has an upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is not determined to be below a predetermined friction range, the estimated maximum friction coefficient μp est It does not output. Therefore, the calculated slip ratio s c , or calculate the coefficient of friction μ c The estimated maximum friction coefficient μp varies with respect to the brush model characteristics. est If there is a risk of deviation from the maximum friction coefficient μp, the estimated maximum friction coefficient μp est This prevents the output from being displayed.

[0086] As described above, the control device 1 of this embodiment calculates the slip ratio s based on the detection signal. c and calculated friction coefficient μ c A calculation unit 10 that calculates the slip rate s c Information and calculation of friction coefficient μ c The control device 1 includes a storage unit 20 that stores a set storage quantity linked to the information. The control device 1 also includes a brush model formula and a calculated slip rate s c Using the model friction coefficient μ md The control device 1 includes a model calculation unit 30 that calculates multiple maximum model friction coefficients μp set by the model calculation unit 30. md High accuracy maximum friction coefficient μp jud A precision determination unit 40 that determines whether or not each of the following is true, and an estimated maximum friction coefficient μp est The control device 1 includes a maximum friction coefficient estimation unit 50 that extracts the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min An upper and lower limit extraction unit 60 for extracting the upper and lower limits, and an estimated maximum friction coefficient μp est The system includes an output determination unit 70 that determines whether or not to output to the outside. The output determination unit 70 determines the upper limit maximum friction coefficient μp maxand the lower limit of the maximum coefficient of friction μp min If the difference is not determined to be below a predetermined friction range, the estimated maximum friction coefficient μp est It does not output to the outside. Also, the output determination unit 70 determines the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is determined to be less than or equal to a predetermined friction range, the estimated maximum friction coefficient μp est Output to an external source.

[0087] According to this, the control device 1 has an upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is less than or equal to the judgment friction range, the estimated maximum friction coefficient μp est It does not output. Therefore, the calculated slip ratio s c , or calculate the coefficient of friction μ c The estimated maximum friction coefficient μp varies with respect to the brush model characteristics. est If there is a risk that the estimated maximum friction coefficient μp will deviate from the maximum friction coefficient μp, the control device 1 will determine the estimated maximum friction coefficient μp est This avoids outputting the maximum friction coefficient μp, which may have poor accuracy. est This avoids the output of the incorrect value and allows for the accurate determination of the estimated maximum friction coefficient μp. est Because it can output only the maximum friction coefficient μp, it is possible to estimate the maximum friction coefficient μp with high accuracy.

[0088] Furthermore, according to the above embodiment, the following effects can be obtained.

[0089] (1) In the above embodiment, the model calculation unit 30 calculates the maximum model friction coefficient μp md The minimum value of is set to 0, and the maximum friction coefficient of the model μp md The maximum value is set to 1, and the model's maximum slip ratio sp md The minimum value of is set to 0, and the maximum slip ratio of the model is sp. md The maximum value of is set to 1. In addition, the model calculation unit 30 calculates the maximum model friction coefficient μp mdBy setting both the maximum slip ratio and the model to any value within the range from the minimum to the maximum, multiple brush model characteristics are obtained.

[0090] According to this, the maximum friction coefficient estimation unit 50 estimates the maximum friction coefficient μp from the entire range of possible values. est It is possible to find this.

[0091] (2) In the above embodiment, the upper and lower limit extraction unit 60 is determined by the accuracy determination unit 40, which determines the high accuracy maximum friction coefficient μp jud The model determined the maximum friction coefficient μp to be... md Of these, the highest value is the high-accuracy maximum friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max The extraction is performed as follows. In addition, the upper and lower limit extraction unit 60 determines the accuracy determination unit 40 to determine the high-accuracy maximum friction coefficient μp jud The model determined the maximum friction coefficient μp to be... md Of these, the highest accuracy maximum friction coefficient μp has the smallest value. jud Lower limit maximum coefficient of friction μp min Extract it as follows.

[0092] According to this, the maximum friction coefficient μp can be easily determined with high accuracy. jud and lower limit of maximum friction coefficient μp min Because it is easier to obtain, the processing load on the control device 1 is reduced, and the control device 1 can obtain the high-accuracy maximum friction coefficient μp jud and lower limit of maximum friction coefficient μp min This can reduce the time required to extract the data.

[0093] (3) In the above embodiment, the model calculation unit 30 calculates the model error Err for each brush model characteristic using a plurality of calculated slip ratios s c The calculated friction coefficient μ associated with each c And multiple calculated slip rates s c The model friction coefficient μ can be derived from each of these. md The error is calculated and the calculated errors are summed up. The accuracy determination unit 40 determines that the model error Err is a predetermined determination threshold Err. _thBased on whether it is smaller or smaller, multiple model maximum friction coefficients μp are set. md High accuracy maximum friction coefficient μp jud Determine whether each case is true or false.

[0094] According to this, the judgment threshold Err _th Since this is pre-set, the processing load on the control device 1 is reduced, and the control device 1 is able to determine the Err threshold. _th Based on high accuracy, the maximum coefficient of friction μp jud This can shorten the time required to make a determination.

[0095] (Second Embodiment) Next, the second embodiment will be described with reference to Figures 8 and 9. In this embodiment, some of the control processing performed by the storage unit 20 and the model calculation unit 30 differs from that of the first embodiment. Otherwise, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0096] The control process executed by the control device 1 of this embodiment will be described with reference to the flowchart shown in Figure 8. Note that the processes in steps S10 to S20 and S50 to S150 in the control process shown in Figure 8 are the same as the processes in steps S10 to S20 and S50 to S150 described using Figure 4 in the first embodiment, so the explanation of those processes may be omitted.

[0097] In step S20, the storage unit 20 stores the calculated slip ratio s obtained from the slip ratio calculation unit 11 at predetermined control cycle intervals. c Information and the calculated friction coefficient μ obtained from the friction coefficient calculation unit 12 at predetermined control cycle intervals. c The information is linked and only the quantity to be stored is stored. Then, in step S22, the storage unit 20 calculates the slip rate s of the stored quantity. c Based on the information obtained, the slip rate s of the stored quantity is calculated. c Of these, the calculated slip rate s has the largest value. cExtracts the stored quantity. The storage unit 20 calculates the friction coefficient μ. c Based on the information obtained, the friction coefficient μ is calculated for the stored quantity. c Of these, the largest value is the calculated friction coefficient μ. c Extract the following slip rate s for calculating the storage quantity acquired by the storage unit 20. c Of these, the calculated slip rate s has the largest value. c Maximum calculated slip rate s c_max It is referred to as such. In addition, the friction coefficient μ is used to calculate the storage quantity acquired by the storage unit 20. c Of these, the largest value is the calculated friction coefficient μ. c Maximum calculation of friction coefficient μ c_max It is called that.

[0098] The storage unit 20 stores the calculated slip ratio group s c [0:N] Information and calculated friction coefficient group μ c In addition to the information [0:N], the maximum calculated slip ratio s c_max Information and maximum calculated friction coefficient μ c_max The information is sent to the model calculation unit 30.

[0099] Then, by repeatedly executing the processes from steps S32 to S50, the control device 1 obtains the maximum model slip ratio sp for acquiring the brush model characteristics. md and the maximum friction coefficient of the model μp md The model calculation unit 30 of this embodiment sets the maximum model slip ratio sp in step S32 in order to obtain the brush model characteristics. md Calculate the slip rate s for each c The maximum slip ratio of the model sp is set to a value greater than or equal to any of the following values. Specifically, in step S32, the first of the repeatedly executed steps S32 to S90, the model calculation unit 30 sets the maximum slip ratio of the model sp as shown in Figure 8. md Maximum calculated slip rate s c_max Set to the maximum slip ratio sp of the model. In other words, the model calculation unit 30 of this embodiment sets the maximum slip ratio sp of the model. md The minimum value of the slip ratio s is calculated to the maximum value. c_max Set to this.

[0100] Furthermore, in step S42, the model calculation unit 30 of this embodiment sets the maximum model friction coefficient μp in order to obtain the brush model characteristics. md Calculate the friction coefficient μ for each. c The value is set to be greater than or equal to any of the following values. Specifically, in step S42, the first of the repeatedly executed steps S32 to S90, the model calculation unit 30 sets the maximum friction coefficient of the model μp as shown in Figure 8. md Maximum calculation of friction coefficient μ c_max Set to the following. In other words, the model calculation unit 30 of this embodiment sets the model maximum friction coefficient μp md The minimum value of the friction coefficient μ is used to calculate the maximum friction coefficient. c_max Set to this.

[0101] In the subsequent step S50, the model calculation unit 30 calculates the set maximum slip ratio s c_max and the maximum calculated friction coefficient μ c_max Based on this, the parameters H and K of the brush model equation are calculated. Then, in step S60, the model calculation unit 30 calculates the set maximum calculated slip ratio s c_max and the maximum calculated friction coefficient μ c_max Obtain the brush model characteristics in this case.

[0102] The model calculation unit 30 repeatedly executes the process in step S42 to determine the maximum friction coefficient of the model μp md The maximum friction coefficient of the model μp until its value becomes 1.0 md Maximum calculation of friction coefficient μ c_max The model calculation unit 30 calculates the maximum friction coefficient μ. c_max Over a larger range, the maximum friction coefficient of the model μp md The value is increased by 0.1 each time. Furthermore, the model calculation unit 30 repeatedly executes the process in step S32 to determine the model maximum slip ratio sp md Model maximum slip rate sp until the value becomes 1.0 md Maximum calculated slip rate s c_max The model calculation unit 30 calculates the maximum slip ratio s. c_maxOver a larger range, the maximum slip rate of the model (sp) md Add 0.01 to the value.

[0103] As a result, the model calculation unit 30 calculates the set maximum model friction coefficient μp, as shown in Figure 9. md and the maximum slip ratio of the model sp md The corresponding brush model characteristics can be obtained. For example, as shown in Figure 9, the maximum calculated friction coefficient μ c_max If it is greater than 0.1 and less than 0.2, the model calculation unit 30 calculates the maximum model friction coefficient μp md The brush model characteristics are not obtained when set to 0.1. Note that the hatched area in Figure 9 represents the maximum model friction coefficient μp that is not set by the model calculation unit 30 of this embodiment. md and the maximum slip ratio of the model sp md This indicates the range. Furthermore, the dashed rectangle in Figure 9 represents the maximum model friction coefficient μp that is not set by the model calculation unit 30 of this embodiment. md and the maximum slip ratio of the model sp md The setting values ​​are shown. In addition, the brush model characteristics shown by the dashed line in Figure 9 are brush model characteristics that are not acquired by the model calculation unit 30 of this embodiment.

[0104] Then, the model calculation unit 30 calculates the model error Err for each brush model characteristic based on the brush model characteristics acquired in this way, and sets the maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud It determines whether or not this is the case. Then, the model calculation unit 30 calculates the set maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud In this case, this high-accuracy maximum friction coefficient μp jud In addition to storing the model error Err, the model error Err is reduced to a smaller model error Err. jud Remember it as such.

[0105] Thus, the maximum model slip ratio sp is set to obtain the brush model characteristics. md The slip ratio s is calculated. cSet to a value greater than any of the following, and the maximum friction coefficient of the model μp md Calculate the friction coefficient μ c Explain why you should set it to a value greater than any of the above values.

[0106] The model calculation unit 30 obtains the characteristics of multiple brush models by calculating the maximum slip ratio sp of multiple models. md and multiple models maximum friction coefficient μp md The following are set. Then, the model calculation unit 30 calculates the set maximum model friction coefficient μp based on the acquired brush model characteristics. md From among them, the highest accuracy maximum friction coefficient μp jud The maximum friction coefficient estimation unit 50 extracts the maximum friction coefficient μp, which is calculated by the model calculation unit 30 with high accuracy. jud The maximum friction coefficient μp determined to be the model md From among them, the estimated maximum coefficient of friction μp est The control device 1 estimates the maximum friction coefficient estimation unit 50, which calculates the maximum slip ratio sp of the model set by the model calculation unit 30. md and the maximum friction coefficient of the model μp md Based on the brush model characteristics obtained, estimate the maximum friction coefficient μp est We estimate this.

[0107] Here, the maximum friction coefficient μp determined by the control device 1 of this embodiment is the friction coefficient at the slip ratio just before the tire starts to slip in the region where the tire does not slip. The maximum friction coefficient estimation unit 50 estimates this maximum friction coefficient μp as the maximum friction coefficient μp est It is estimated as follows. For this reason, the maximum friction coefficient μp estimated by the maximum friction coefficient estimation unit 50 based on the brush model characteristics is the calculated friction coefficient μ calculated by the calculation unit 10 based on the detection signal obtained from the detection unit S. c The size is as described above. Furthermore, the slip ratio at which the maximum friction coefficient μp occurs is calculated slip ratio s calculated by the calculation unit 10 based on the detection signal obtained from the detection unit S. c The above dimensions apply.

[0108] Therefore, the estimated maximum coefficient of friction μp estThe corresponding brush model characteristics are calculated slip ratio s c The above models have a maximum slip ratio of sp md And, the calculated friction coefficient μ c The maximum friction coefficient μp of the above model md This corresponds to the brush model characteristics in combination with the other. In other words, the calculated friction coefficient μ c Smaller model maximum slip ratio sp md The slip rate s is calculated c Smaller model maximum coefficient of friction μp md The maximum friction coefficient μp is estimated from the brush model characteristics obtainable from the combination of these factors. est It is not possible to determine this. Therefore, the calculated friction coefficient μ c Smaller model maximum slip ratio sp md The slip rate s is calculated c Smaller model maximum coefficient of friction μp md Information such as model error Err, which is obtained from the combination of brush model characteristics, is unnecessary.

[0109] Therefore, the model calculation unit 30 of this embodiment calculates the maximum model slip ratio sp for obtaining the brush model characteristics. md The slip ratio s is calculated. c Set the value to the above, and the maximum friction coefficient of the model μp md Calculate the friction coefficient μ c Set to the above value. This reduces the number of operations performed in steps S32 to S90, which are executed repeatedly, thereby reducing the processing load on the control device 1, and also allows the control device 1 to estimate the maximum friction coefficient μp est This can reduce the time required to produce output.

[0110] The other configurations are the same as in the first embodiment. The control device 1 of this embodiment can obtain the same effects and advantages as in the first embodiment, which are achieved from a configuration that is the same as or equivalent to that of the first embodiment.

[0111] (Third embodiment) Next, the third embodiment will be described with reference to Figures 10 to 11. In this embodiment, some of the control processing performed by the model calculation unit 30 and the accuracy determination unit 40 differs from that of the first embodiment. Otherwise, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0112] The control process executed by the control device 1 of this embodiment will be described with reference to the flowchart shown in Figure 10. Note that the processes from steps S10 to S70 and S90 to S150 in the control process shown in Figure 10 are the same as the processes from steps S10 to S70 and S90 to S150 described using Figure 4 in the first embodiment, so the explanation of those processes may be omitted. However, the order in which the process of step S90 described using Figure 4 in the first embodiment is executed is different from that of the first embodiment.

[0113] In the first embodiment, the control device 1 calculates a model error Err for each brush model characteristic in the repeatedly executed steps S30 to S90. The control device 1 then determines that the calculated model error Err is equal to a preset judgment threshold Err. _th If it is smaller, the maximum friction coefficient of the model μp md High accuracy maximum friction coefficient μp jud Determine whether or not it is true.

[0114] In contrast, the control device 1 of this embodiment has a determination threshold Err _th This is not pre-set. The control device 1 determines the judgment threshold Err based on the model error Err calculated for each brush model characteristic. _th Set the set judgment threshold Err _th Based on this, the maximum friction coefficient of the model μp md High accuracy maximum friction coefficient μp jud Determine whether or not it is true.

[0115] Specifically, in step S70 of the repeatedly executed steps S30 to S70, the model calculation unit 30 calculates the model error Err for each brush model characteristic. The model calculation unit 30 calculates the maximum model slip ratio sp set to obtain the brush model characteristics. md Information and model maximum friction coefficient μp md The information and the calculated model error Err are transmitted to the accuracy determination unit 40. In step S72, the accuracy determination unit 40 receives the maximum model slip ratio sp obtained from the model calculation unit 30. md Information and the model's maximum friction coefficient μp md The information about the model error Err is linked and stored in memory.

[0116] The model calculation unit 30 repeats the process from step S30 to step S72 to calculate the maximum friction coefficient μp of the model. md The maximum friction coefficient of the model μp until its value becomes 1.0 md Add 0.1 to each value, and the maximum slip ratio of the model, sp md Model maximum slip rate sp until it reaches 1.00 md The value is increased by 0.01 each time. Then, the accuracy determination unit 40 determines the set maximum slip rate sp for each model. md and the maximum friction coefficient μp for each model md The model error Err, obtained from the combination of these factors, is acquired from the model calculation unit 30 for each brush model characteristic. As a result, the accuracy determination unit 40 receives the model error Err for each brush model characteristic, as shown in Figure 11, and the model maximum slip ratio sp md and the maximum friction coefficient μp md It is stored in association with the following. Below, the model error Err for each brush model characteristic stored by the accuracy determination unit 40 is stored as the stored error Err. _mem This may be written as such. Note that Figure 11 only shows a portion of the model error Err for each brush model characteristic.

[0117] Then, in step S100, the storage unit 20 stores the N calculated slip rates s that have been stored. c Information and N calculated friction coefficients μ stored cThe information is erased. In the following step S102, the accuracy determination unit 40 determines the stored memory error Err _mem Of these, the maximum value of the memory error Err _mem and the minimum value memory error Err _mem Extract the following: Memory error Err _mem Of these, the maximum value of the memory error Err _mem Maximum error Err _max It is called [this]. Also, memory error Err _mem Of these, the minimum memory error Err _mem Minimum error Err _min It is called that.

[0118] Then, in step S104, the accuracy determination unit 40 determines the extracted maximum error Err _max and minimum error Err _min The judgment threshold Err is based on the difference between the two. _th The following is set. Specifically, the accuracy determination unit 40 sets the determination threshold Err as shown in Figure 10. _th Maximum error Err _max and minimum error Err _min The value is set to the value obtained by multiplying the difference by a predetermined coefficient a. The predetermined coefficient a is determined in step S106 described later, where the high-accuracy maximum friction coefficient μp jud A judgment threshold Err that accurately determines the case. _th This is a coefficient for obtaining the coefficient, which can be determined, for example, by conducting an experiment beforehand on a road surface with a known coefficient of friction. Furthermore, the predetermined coefficient a is the judgment threshold Err, as shown in Figure 11. _th Maximum error Err _max and minimum error Err _min It is determined to be set between the following. The predetermined coefficient a may be a fixed value set in advance, or the maximum error Err _max and minimum error Err _min The value may be arbitrarily set according to the difference between the two. The predetermined coefficient a is the judgment threshold Err as shown in Figure 11. _th Maximum error Err _max Smallest error Err _min It is preferable to set the value to be close to the desired value.

[0119] Then, the accuracy determination unit 40 determines the set determination threshold Err _th Based on this, the maximum friction coefficient μp of the model is set to obtain the brush model characteristics. md High probability that this corresponds to the maximum coefficient of friction μp jud It determines whether or not this is the case. Specifically, in step S106, the accuracy determination unit 40 determines the memory error Err for each brush model characteristic to be stored. _mem Of these, the judgment threshold Err set in step S104 _th Smaller model error Err jud The small model error Err is extracted. Then, in step S90, the accuracy determination unit 40 determines the extracted small model error Err jud The maximum friction coefficient μp of the model linked to this md High-accuracy maximum friction coefficient μp jud It is stored as follows. The accuracy determination unit 40 determines the storage error Err for each brush model characteristic to be stored. _mem Each has a judgment threshold Err _th It determines whether it is smaller or not. The accuracy determination unit 40 then determines the determination threshold Err _th Smaller model error Err jud The maximum friction coefficient μp of the model associated with each md All with high accuracy and maximum friction coefficient μp jud Remember it as such.

[0120] In step S110, the upper and lower limit extraction unit 60 determines the accuracy determination unit 40 when the determination threshold Err _th High-accuracy maximum friction coefficient μp extracted using jud From among them, the upper limit of the maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min Specifically, the upper and lower limit extraction unit 60 extracts the result when the accuracy determination unit 40 determines the determination threshold Err _th High-accuracy maximum friction coefficient μp extracted using jud The highest value among them is the maximum high-accuracy friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max The extraction is performed as follows. In addition, the upper and lower limit extraction unit 60 determines the accuracy determination unit 40 when the determination threshold Err _th High-accuracy maximum friction coefficient μp extracted using judThe smallest value among them is the high-accuracy maximum friction coefficient μp jud Lower limit maximum coefficient of friction μp min Extract it as follows.

[0121] In step S120, the maximum friction coefficient estimation unit 50 determines that the accuracy determination unit 40 has a determination threshold Err _th The small model error Err was determined using this method. jud From minimum model error minErr jud Extract the minimum model error minErr. jud This is the memory error Err stored in the accuracy determination unit 40. _mem Of these, the smallest value is the memory error Err _mem It is the same as above. Then, in step S130, the maximum friction coefficient estimation unit 50 extracts the minimum model error minErr jud Estimated maximum friction coefficient μp associated with est Extract the extracted estimated maximum friction coefficient μp est The information is transmitted to the output determination unit 70.

[0122] In step S140, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If it is determined that the difference is less than or equal to a predetermined friction range, in step S150, the estimated maximum friction coefficient μp est Output the information to an external source.

[0123] Next, the model calculation unit 30 of this embodiment calculates a determination threshold Err based on the model error Err calculated for each brush model characteristic. _th This explains the reason for setting it.

[0124] The calculation slip rate s calculated by the calculation unit 10 c and calculated friction coefficient μ c The slip ratio s changes depending on the vehicle's driving conditions, such as the condition of the road surface and the vehicle's speed. c and calculated friction coefficient μ cAs this changes, the model error Err also changes depending on the vehicle's driving conditions. Therefore, the judgment threshold Err, which is set to a fixed value, _th Using high accuracy, the maximum friction coefficient μp jud When extracted, the high-accuracy maximum friction coefficient μp jud There is a risk that the extraction accuracy will decrease. That is, the accuracy determination unit 40 will have a high accuracy maximum friction coefficient μp jud There is a risk that it may not be possible to extract it accurately. As a result, the upper and lower limit extraction unit 60 will be the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min The output determination unit 70 can no longer extract the maximum friction coefficient μp with high accuracy. est There is a risk that the accuracy of determining whether or not to output this information externally will decrease.

[0125] In response, the model calculation unit 30 calculates the slip rate s calculated by the calculation unit 10. c and calculated friction coefficient μ c Based on this, the model error Err is calculated for each brush model characteristic. Then, the model calculation unit 30 determines a judgment threshold Err based on the model error Err calculated for each brush model characteristic. _th Set it.

[0126] According to this, the high-accuracy maximum friction coefficient μp jud The Err threshold is used to determine whether or not this is true. _th The calculated slip ratio s changes depending on the vehicle's driving conditions. c and calculated friction coefficient μ c This can be used to correspond to the model error Err calculated from the accuracy determination unit 40. _th Using high accuracy, the maximum friction coefficient μp jud Compared to the case where the determination was made, the determination accuracy can be improved. As a result, the upper and lower limit extraction unit 60 can determine the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min The output determination unit 70 can accurately extract the maximum friction coefficient μp est This makes it easier to correctly determine whether or not to output the information to the outside. Therefore, the estimated maximum friction coefficient μp, which may have poor accuracy, can be easily determined.est This avoids the output of the incorrect value and allows for the accurate determination of the estimated maximum friction coefficient μp. est Because it can output only the maximum friction coefficient μp, it is possible to estimate the maximum friction coefficient μp with high accuracy.

[0127] The other configurations are the same as in the first embodiment. The control device 1 of this embodiment can obtain the same effects as those obtained from a configuration that is the same as or equivalent to that of the first embodiment. Although this embodiment is a modification based on the first embodiment, it is possible to combine this embodiment with either the first or second embodiment.

[0128] (Fourth Embodiment) Next, the fourth embodiment will be described with reference to Figures 12 to 13. In this embodiment, some of the control processing performed by the accuracy determination unit 40 differs from that of the first and third embodiments. Otherwise, it is the same as the first and third embodiments. For this reason, in this embodiment, we will mainly describe the parts that differ from the first and third embodiments, and we may omit the description of parts that are the same as the first and third embodiments.

[0129] The control process executed by the control device 1 of this embodiment will be described with reference to the flowchart shown in Figure 12. Note that the processes in steps S10 to S70 and S130 to S150 in the control process shown in Figure 12 are the same as the processes in steps S10 to S70 and S130 to S150 described using Figure 4 in the first embodiment, so the explanation of those processes may be omitted. Also, the process in step S72 in the control process shown in Figure 12 is the same as the process in step S72 described using Figure 10 in the third embodiment, so the explanation of those processes may be omitted.

[0130] The control device 1 of the first and third embodiments has a determination threshold Err _th Based on this, the maximum friction coefficient of the model μp md High accuracy maximum friction coefficient μp judIt determines whether or not this is the case. In response to this, the control device 1 of this embodiment determines the determination threshold Err _th Based on this, the maximum friction coefficient of the model μp md High accuracy maximum friction coefficient μp jud Without determining whether or not it is true, estimate the maximum friction coefficient μp est We estimate this.

[0131] Specifically, in the repeatedly executed steps S30 to S72, in step S70, the model calculation unit 30 calculates the model error Err for each brush model characteristic. Then, in step S72, the accuracy determination unit 40 determines the maximum model slip ratio sp obtained from the model calculation unit 30. md Information and the model's maximum friction coefficient μp md The information and the model error Err are linked and stored. The accuracy determination unit 40 repeats the process in step S72 to determine the set maximum slip ratio sp for each model. md and the maximum friction coefficient μp for each model md The model error Err, obtained from the combination of these factors, is acquired from the model calculation unit 30 for each brush model characteristic. As a result, the accuracy determination unit 40 receives the model error Err for each brush model characteristic from the model maximum slip ratio sp, as shown in Figure 13. md and the maximum friction coefficient μp md It is stored in association with the following. Below, the model error Err for each brush model characteristic stored by the accuracy determination unit 40 is stored as the stored error Err. _mem This may be written as such. Note that Figure 13 only shows a portion of the model error Err for each brush model characteristic.

[0132] In step S108, the accuracy determination unit 40 determines the stored memory error Err _mem Among them, in ascending order of value: Memory error Err _memA predetermined quantity is extracted. The predetermined quantity extracted by the accuracy determination unit 40 is set based on the total amount of model error Err, for example, an amount of 10% or less of the total amount of model error Err obtained by the model calculation unit 30 by repeating the processing of steps S30 to S70. In this embodiment, the accuracy determination unit 40 stores the stored error Err as shown in Figure 13. _mem Among them, in ascending order of value: Memory error Err _mem Extract five of them.

[0133] In the following step S90, the accuracy determination unit 40 determines the memory error Err extracted in step S108. _mem The maximum friction coefficient μp of the model associated with each md The accuracy determination unit 40 then extracts the memory error Err extracted in step S108. _mem Small model error Err jud It is stored as such, and the extracted memory error Err _mem The maximum friction coefficient μp of the model associated with each md High-accuracy maximum friction coefficient μp jud Remember it as such.

[0134] In step S110, the upper and lower limit extraction unit 60 determines the high-accuracy maximum friction coefficient μp extracted by the accuracy determination unit 40. jud From among them, the upper limit of the maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min Specifically, the upper and lower limit extraction unit 60 extracts the memory error Err extracted in step S108. _mem High-accuracy maximum friction coefficient μp associated with each jud The highest value among them is the maximum high-accuracy friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max It is extracted as follows. In addition, the upper and lower limit extraction unit 60 extracts the memory error Err extracted in step S108. _mem High-accuracy maximum friction coefficient μp associated with each jud The smallest value among them is the high-accuracy maximum friction coefficient μp jud Lower limit maximum coefficient of friction μp min Extract it as follows.

[0135] In step S122, the maximum friction coefficient estimation unit 50 determines the storage error Err of a predetermined quantity extracted by the accuracy determination unit 40. _mem Of these, the smallest value is the memory error Err _mem Extracts the maximum friction coefficient. Then, in step S130, the maximum friction coefficient estimation unit 50 calculates the memory error Err _mem The maximum friction coefficient μp of the model linked to md Estimated maximum coefficient of friction μp est Extracted as follows, the extracted estimated maximum friction coefficient μp est The information is transmitted to each of the output determination units 70.

[0136] In step S140, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If it is determined that the difference is less than or equal to a predetermined friction range, in step S150, the estimated maximum friction coefficient μp est Output the information to an external source.

[0137] As described above, the upper and lower limit extraction unit 60 of this embodiment extracts a predetermined number of model errors Err in ascending order of value. The upper and lower limit extraction unit 60 then associates the high-accuracy maximum friction coefficient μp with each of the extracted predetermined number of model errors Err. jud Of these, the highest value is the high-accuracy maximum friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max The upper and lower limit extraction unit 60 extracts the high-accuracy maximum friction coefficient μp associated with each of the extracted predetermined quantities of model errors Err. jud Of these, the highest accuracy maximum friction coefficient μp has the smallest value. jud Lower limit maximum coefficient of friction μp min Extract it as follows.

[0138] According to this, the calculated slip ratio s changes depending on the vehicle's driving conditions. c and calculated friction coefficient μ c The high-accuracy maximum friction coefficient μp is calculated based on the model error Err. judIt is possible to determine whether or not this is the case. Therefore, the accuracy determination unit 40 can determine the determination threshold Err, which is set to a fixed value. _th Using high accuracy, the maximum friction coefficient μp jud Compared to the case where the determination was made, the determination accuracy can be improved. As a result, the upper and lower limit extraction unit 60 can determine the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min The output determination unit 70 can accurately extract the maximum friction coefficient μp est This makes it easier to correctly determine whether or not to output the information to the outside. Therefore, the estimated maximum friction coefficient μp, which may have poor accuracy, can be easily determined. est This avoids the output of the incorrect value and allows for the accurate determination of the estimated maximum friction coefficient μp. est Because it can output only the maximum friction coefficient μp, it is possible to estimate the maximum friction coefficient μp with high accuracy.

[0139] The other configurations are the same as in the first embodiment. The control device 1 of this embodiment can obtain the same effects as those obtained from a configuration that is the same as or equivalent to that of the first embodiment. Although this embodiment is a modification based on the first embodiment, it is possible to combine this embodiment with either the first or second embodiment.

[0140] The other configurations are the same as in the first embodiment. The control device 1 of this embodiment can obtain the same effects as those obtained from a configuration that is the same as or equivalent to that of the first embodiment. Although this embodiment is a modification based on the first embodiment, it is possible to combine this embodiment with either the first or second embodiment.

[0141] (Fifth embodiment) Next, the fifth embodiment will be described with reference to Figures 14 to 18. In this embodiment, the output determination unit 70 determines the estimated maximum friction coefficient μp estThe processing after determining that output should not be produced differs from that of the first embodiment. Other than this, it is the same as the first embodiment. Therefore, in this embodiment, the parts that differ from the first embodiment will be mainly described, and explanations of parts that are the same as the first embodiment may be omitted.

[0142] As shown in Figure 14, in this embodiment, the output determination unit 70 has the storage unit 20 connected to the output side. The output determination unit 70 then determines the estimated maximum friction coefficient μp est If it is determined that no output should be produced, information indicating that determination result can be output to the storage unit 20.

[0143] Next, the control processing performed by the control device 1 of this embodiment will be described with reference to the flowchart shown in Figure 15. Note that the processing of steps S10 to S150 in the control processing shown in Figure 15 is the same as the processing of steps S10 to S150 described using Figure 4 in the first embodiment, so the explanation of those processes may be omitted. However, the order in which the processing of step S100 described using Figure 4 in the first embodiment is executed is different from that of the first embodiment.

[0144] In step S140, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If it is determined that the difference is less than or equal to a predetermined friction range, in step S150, the estimated maximum friction coefficient μp est The information is output to the outside. In response, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is not determined to be below a predetermined friction range, the estimated maximum friction coefficient μp est It does not output. The output determination unit 70 then determines the estimated maximum friction coefficient μp est Information indicating the result of determining that output should not be produced is output to the storage unit 20.

[0145] The storage unit 20 estimates the maximum friction coefficient μp from the output determination unit 70. estWhen information is received indicating that it has been determined not to output, in step S160, the calculated slip rate s saved in step S20 is used. c Information and calculation of friction coefficient μ c The amount of information is increased. Specifically, the storage unit 20 calculates the slip rate s in the storage process of the next step S20. c and calculated friction coefficient μ c The quantity to be stored is calculated using the slip rate s set in the storage process of the previous step S20. c and calculated friction coefficient μ c The number of saved values ​​is set to be greater than the number of saved values. In step S170, the accuracy determination unit 40 erases the model error Err information saved in the repeatedly executed step S70. Then, when the process in step S170 is executed, the process returns to step S20.

[0146] Here, as shown by the circle in Figure 16, the storage unit 20 of this embodiment calculates the slip rate s of the storage quantity from the calculation unit 10 within a predetermined time through the storage process in step S20. c Information and calculation of friction coefficient μ c The information can be obtained. However, as mentioned above, the slip rate s for calculating the storage quantity c Information and calculation of friction coefficient μ c The estimated maximum friction coefficient μp is calculated based on the information provided. est If there is a risk that the estimated maximum friction coefficient μp will deviate from the maximum friction coefficient μp, the output determination unit 70 will determine the estimated maximum friction coefficient μp est It does not output.

[0147] In this case, the storage unit 20 sets a larger storage quantity in step S20 by executing the process in step S160. Then, in the next storage process in step S20, the storage unit 20 calculates the slip rate s from the calculation unit 10 during the set predetermined elapsed time. c Information and calculation of friction coefficient μ c Further information can be obtained. As a result, the storage unit 20 will store the calculated slip rate s in the next storage process of step S20, as shown by the circle in Figure 16. c Information and calculation of friction coefficient μ cThe quantity of information can be increased to be greater than the quantity saved in the previous step S20.

[0148] The predetermined elapsed time is set, for example, based on the control cycle in which the detection unit S repeatedly transmits the detection signal to the calculation unit 10. Furthermore, the predetermined elapsed time is set, for example, based on the slip rate s of the storage quantity set by the calculation unit 10 in the next storage process. c Information and calculation of friction coefficient μ c This is set to the time required to retrieve the information.

[0149] The storage unit 20 determines the estimated maximum friction coefficient μp in the output determination unit 70. est If no output is generated, the save process in step S20 is executed again to retrieve the slip rate s calculated from the calculation unit 10. c Information and calculation of friction coefficient μ c Further information is obtained. As a result, the storage unit 20 stores the calculated slip rate s obtained from the calculation unit 10 during a predetermined elapsed time since the storage process in the previous step S20. c Information and calculation of friction coefficient μ c The slip rate s is calculated based on the quantity of information. c Information and calculation of friction coefficient μ c The information is saved. In other words, in the saving process of step S20 which is executed again, the saving unit 20 saves the calculated slip rate s c Information and calculation of friction coefficient μ c The information is saved in the quantity set in step S160.

[0150] Then, in step S60 of the process from steps S30 to S90 which is executed again, the model calculation unit 30 uses the brush model formula to calculate the slip rate s newly stored in the storage unit 20. c Based on each, the model friction coefficient μ md This calculates the slip ratio s newly obtained in step S20, as shown in Figures 17 and 18. c Based on the information, the model friction coefficient μ mdThis allows for the calculation of a new slip rate s before the storage unit 20 increases the storage quantity. c Model friction coefficient μ calculated based on the information md This shows the calculated slip rate s after the storage unit 20 has increased the storage quantity. c Model friction coefficient μ calculated based on the information md This indicates that.

[0151] In the following step S70, the model calculation unit 30 calculates the model friction coefficient μ. md The friction coefficient μ is used to calculate the quantity stored in the storage unit 20. c The model error Err is recalculated using each of these, and the calculated model error Err information is transmitted to the accuracy determination unit 40. Then, in step S80, the accuracy determination unit 40 determines that the model error Err obtained again from the model calculation unit 30 is the determination threshold Err. _th We re-determine whether it is smaller or not.

[0152] The model error Err, which is again obtained from the model calculation unit 30, is the decision threshold Err. _th If it is determined to be smaller, in step S90, the accuracy determination unit 40 determines the maximum model friction coefficient μp associated with the model error Err. md High-accuracy maximum friction coefficient μp jud It is stored as follows. Also, the model error Err obtained again from the model calculation unit 30 is the judgment threshold Err. _th If it is determined to be smaller, the accuracy determination unit 40 sets the model error Err to the smaller model error Err. jud I will remember this as a new record.

[0153] Therefore, the model error Err recalculated in step S70 is the judgment threshold Err. _th If it is smaller, the accuracy determination unit 40 will receive information about this model error Err as small model error Err jud It is stored as follows. In contrast, the model error Err calculated again in step S70 is the judgment threshold Err. _thIf it is greater than this, the accuracy determination unit 40 does not store the information of this model error Err. For this reason, in a given brush model characteristic, the small model error Err was not stored in the previous step S70. jud The model error Err, which was stored as such, is used in step S70 to determine the Err threshold. _th If it is determined to be larger, this model error Err information is not stored.

[0154] The model calculation unit 30 repeatedly executes the processes from step S30 to step S90 and then obtains the calculated slip rate s again in the save process. c and calculated friction coefficient μ c Based on this, the model error Err is calculated for each brush model characteristic. Then, the model calculation unit 30 calculates the set maximum model friction coefficient μp md High accuracy maximum friction coefficient μp jud In this case, this high-accuracy maximum friction coefficient μp jud In addition to storing the model error Err, the model error Err is reduced to a smaller model error Err. jud Remember it as such.

[0155] In step S110, the upper and lower limit extraction unit 60 determines the accuracy determination unit 40 when the determination threshold Err _th The high-accuracy maximum friction coefficient μp was extracted again using this method. jud From among them, again the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min Specifically, the upper and lower limit extraction unit 60 extracts the result when the accuracy determination unit 40 determines the determination threshold Err _th The high-accuracy maximum friction coefficient μp was extracted again using this method. jud The highest value among them is the maximum high-accuracy friction coefficient μp jud The upper limit of the maximum coefficient of friction μp max The extraction is performed as follows. In addition, the upper and lower limit extraction unit 60 determines the accuracy determination unit 40 when the determination threshold Err _th The high-accuracy maximum friction coefficient μp was extracted again using this method. jud The smallest value among them is the high-accuracy maximum friction coefficient μp jud Lower limit maximum coefficient of friction μp min Extract it as follows.

[0156] In step S120, the maximum friction coefficient estimation unit 50 calculates the small model error Err jud From minimum model error minErr jud The minimum model error minErr is extracted again. Then, in step S130, the maximum friction coefficient estimation unit 50 calculates the extracted minimum model error minErr. jud The maximum friction coefficient μp of the model linked to md Let's re-estimate the maximum coefficient of friction μp. est The maximum friction coefficient estimation unit 50 extracts the extracted estimated maximum friction coefficient μp. est The information is transmitted to the output determination unit 70.

[0157] In step S140, the output determination unit 70 determines the upper limit maximum friction coefficient μp max Information and lower limit of maximum friction coefficient μp min Based on the information, the estimated maximum friction coefficient μp is obtained from the maximum friction coefficient estimation unit 50. est The system then determines whether or not to output the information to the outside. Specifically, the output determination unit 70 of this embodiment determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min The difference is recalculated.

[0158] Upper limit of maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If it is determined that the difference is less than or equal to the determined friction range, in step S100, the storage unit 20 calculates the slip rate s of the stored quantity. c Information and calculation of friction coefficient μ c The information is erased. As a result, the storage unit 20 will not be able to retrieve the newly obtained calculated slip rate s from the calculation unit 10 in processing that is performed after this control cycle. c Information and calculation of friction coefficient μ c This information can then be saved. Subsequently, in step S150, the output determination unit 70 determines the estimated maximum friction coefficient μp est Output the information to an external source.

[0159] In response, the output determination unit 70 determines the upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp minIf the difference is not determined to be less than or equal to a predetermined friction range, the process of step S160 is executed again. By executing step S160, the storage unit 20 stores the calculated slip ratio s saved in step S20. c Information and calculation of friction coefficient μ c Increase the amount of information again.

[0160] As described above, the storage unit 20 of this embodiment has an output determination unit 70 that estimates the maximum friction coefficient μp est If the output is not sent externally, the storage quantity in the next step S20 storage process is set to be greater than the storage quantity set in the previous step S20 storage process. Then, the storage unit 20 calculates the slip rate s from the calculation unit 10. c Information and calculation of friction coefficient μ c By obtaining further information, the slip rate s can be calculated. c Information and calculation of friction coefficient μ c The information is saved in a quantity greater than the quantity saved in the previous save process in step S20. The model calculation unit 30 calculates the slip rate s of the saved quantity saved in the previous save process. c and calculated friction coefficient μ c Calculation of the slip rate s for the larger amount of stored items c and calculated friction coefficient μ c The model error Err is recalculated using the method. The accuracy determination unit 40 determines the maximum model friction coefficient μp based on the model error Err obtained by the model calculation unit 30. md High accuracy maximum friction coefficient μp jud The determination is made again as to whether or not it is true. The maximum friction coefficient estimation unit 50 determines the high-accuracy maximum friction coefficient μp jud The model's maximum friction coefficient μp was determined to be... md From among them, we will again estimate the maximum friction coefficient μp est The upper and lower limit extraction unit 60 extracts the upper limit maximum friction coefficient μp max and lower limit of maximum friction coefficient μp min The result is extracted again. The output determination unit 70 determines the estimated maximum friction coefficient μp est The system re-determines whether or not to output the data externally.

[0161] By the way, the calculated slip ratio sc and calculated friction coefficient μ c When the amount of information for each is small, the calculated slip rate s c and calculated friction coefficient μ c The influence of individual variations tends to become larger. Specifically, the calculated slip rate s c and calculated friction coefficient μ c The slip rate s is calculated by the variation of each individual. c and calculated friction coefficient μ c If the model error Err calculated using varies, the upper limit of the maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min The difference becomes large. Therefore, the calculated slip rate s c and calculated friction coefficient μ c When the amount of information is limited, the estimated maximum friction coefficient μp is shown by the dashed triangle in Figures 16 and 17. est The range of possible values ​​increases, and the estimated maximum friction coefficient μp est There is a risk that the estimation accuracy will be low. For this reason, the control device 1 of this embodiment has an upper limit maximum friction coefficient μp max and the lower limit of the maximum coefficient of friction μp min If the difference is greater than the determined friction coefficient, the estimated maximum friction coefficient μp is as shown in Figure 16. est It does not output.

[0162] In contrast, the control device 1 of this embodiment has an output determination unit 70 which estimates the maximum friction coefficient μp est If the result is not output externally, the calculated slip rate s c and calculated friction coefficient μ c Each amount of information is estimated to be the maximum friction coefficient μp est The control device 1 acquires more of the calculated slip ratio s than the control process that determined not to output it externally. c and calculated friction coefficient μ c Based on this, the model error Err is recalculated, and the estimated maximum friction coefficient μp is estimated based on the recalculated model error Err. est The system re-determines whether or not to output the data externally.

[0163] According to this, the calculated slip ratio sc and the calculated friction coefficient μ c The influence by each variation can be suppressed. Specifically, the calculated slip ratio s c and the calculated friction coefficient μ c Since the variation of the model error Err caused by the variation of each can be suppressed, the upper limit maximum friction coefficient μp max and the lower limit maximum friction coefficient μp min The difference between them can be made small. For this reason, by increasing the information amount of each of the calculated slip ratio s c and the calculated friction coefficient μ c As shown in FIGS. 16 and 18, the range in which the estimated maximum friction coefficient μp indicated by the solid triangle can be obtained becomes small, and the estimated accuracy of the estimated maximum friction coefficient μp est can be increased. Therefore, it is possible to avoid the output of the estimated maximum friction coefficient μp which may have poor accuracy, and as shown in FIG. 16, only the estimated maximum friction coefficient μp accurately obtained est can be output, so that the maximum friction coefficient μp can be estimated with high accuracy. est can be output, so that the maximum friction coefficient μp can be estimated with high accuracy. est can be output, so that the maximum friction coefficient μp can be estimated with high accuracy.

[0164] Other configurations are the same as those in the first embodiment. The control device 1 of the present embodiment can obtain the same operational effects as those achieved by the same or equivalent configurations as in the first embodiment in the same manner. Note that although the present embodiment is a modified example based on the first embodiment, the present embodiment can be combined with any of the first to fourth embodiments.

[0165] (Modified Example of the Fifth Embodiment) In the above-described fifth embodiment, the case where the output determination unit 70 does not output the estimated maximum friction coefficient μp est has been described in which the storage unit 20 further acquires the information of the calculated slip ratio s c and the information of the calculated friction coefficient μ c from the calculation unit 10 during the predetermined elapsed time set, but the present invention is not limited to this. For example, the output determination unit 70 may determine whether the estimated maximum friction coefficient μp estIf no output is provided, the storage unit 20 calculates the slip rate s from the calculation unit 10 by a predetermined increase amount set in advance. c Information and calculation of friction coefficient μ c The configuration may also include further acquisition of information. In this case, the increased quantity may be set to the same quantity as the quantity stored in the previous storage process, or it may be set to a quantity less than or greater than the quantity stored in the previous storage process.

[0166] (Sixth Embodiment) Next, the sixth embodiment will be described with reference to Figures 19 to 21. In this embodiment, some of the control processing performed by the storage unit 20 differs from that of the fifth embodiment. Otherwise, it is the same as the fifth embodiment. For this reason, in this embodiment, the parts that differ from the fifth embodiment will be mainly described, and the parts that are the same as the fifth embodiment may be omitted from the description.

[0167] As shown in Figure 19, the detection unit S of this embodiment has a storage unit 20 connected to its output side. The detection unit S is capable of transmitting detection signals to the storage unit 20 according to the detection values ​​detected by various sensors. For example, the vehicle speed sensor outputs a detection signal to the storage unit 20 according to the vehicle speed.

[0168] Next, the control processing performed by the control device 1 of this embodiment will be described with reference to the flowchart shown in Figure 20. Note that the processing in steps S10 to S150 and step S170 in the control processing shown in Figure 20 is the same as the processing in steps S10 to S150 and step S170 described in the first and fifth embodiments, so the explanation of those processes may be omitted.

[0169] The storage unit 20 estimates the maximum friction coefficient μp from the output determination unit 70. est When information is received indicating that it has been determined not to output, in step S162, the calculated slip rate s saved in step S20 is used. c Information and calculation of friction coefficient μ cThe amount of information is increased. Specifically, the storage unit 20 calculates the slip rate s in the storage process of the next step S20. c and calculated friction coefficient μ c The quantity to be stored is calculated using the slip rate s set in the storage process of the previous step S20. c and calculated friction coefficient μ c Set the quantity to be greater than the number of items to be stored.

[0170] Here, as shown by the circle in Figure 21, the storage unit 20 of this embodiment calculates the slip rate s of the storage quantity from the calculation unit 10 during the storage process in step S20 while the vehicle travels a predetermined distance. c Information and calculation of friction coefficient μ c The information can be obtained. However, as mentioned above, the slip rate s for calculating the storage quantity c Information and calculation of friction coefficient μ c The estimated maximum friction coefficient μp is calculated based on the information provided. est If there is a risk that the estimated maximum friction coefficient μp will deviate from the maximum friction coefficient μp, the output determination unit 70 will determine the estimated maximum friction coefficient μp est It does not output.

[0171] In this case, the storage unit 20 sets a large storage quantity in step S162. Then, in the next storage process in step S20, the storage unit 20 calculates the slip ratio s from the calculation unit 10 while the vehicle travels the set predetermined distance. c Information and calculation of friction coefficient μ c Further information can be obtained. As a result, the storage unit 20 will store the calculated slip rate s in the next storage process of step S20, as shown by the circle in Figure 21. c Information and calculation of friction coefficient μ c The amount of information can be increased to more than the amount saved in the previous step S20. The storage unit 20 calculates, for example, the vehicle's mileage based on the detection signal from the vehicle speed sensor in the detection unit S and the elapsed time.

[0172] The predetermined travel distance is set based on the distance interval over which the vehicle occupants determine the road surface condition, for example, 10m. Furthermore, the predetermined travel distance is used, for example, in the next saving process, to calculate the slip rate s of the saved quantity set by the calculation unit 10. c Information and calculation of friction coefficient μ c It is set to the mileage required to obtain the information.

[0173] The storage unit 20 determines the estimated maximum friction coefficient μp in the output determination unit 70. est If no output is generated, the save process in step S20 is executed again to retrieve the slip rate s calculated from the calculation unit 10. c Information and calculation of friction coefficient μ c Further information is obtained. As a result, the storage unit 20 stores the calculated slip rate s obtained from the calculation unit 10 during the time the vehicle has traveled a predetermined distance since the storage process in the previous step S20. c Information and calculation of friction coefficient μ c The slip rate s is calculated based on the quantity of information. c Information and calculation of friction coefficient μ c The information is saved. In other words, in the saving process of step S20 which is executed again, the saving unit 20 saves the calculated slip rate s c Information and calculation of friction coefficient μ c The information is saved in the quantity set in step S162. In step S170, the accuracy determination unit 40 deletes the information of the model error Err that was saved in the repeatedly executed step S70.

[0174] The content of the control processing in steps S20 to S150 is the same as the processing in steps S20 to S150 described in the fifth embodiment.

[0175] According to this, the calculated slip ratio s c and calculated friction coefficient μ c This can suppress the effects of variations in each component. Specifically, the calculated slip rate s c and calculated friction coefficient μ c Because the variation in the model error Err caused by the variation in each component can be suppressed, the upper limit of the maximum friction coefficient μpmax and the lower limit of the maximum coefficient of friction μp min The difference can be reduced. Therefore, the calculated slip rate s c and calculated friction coefficient μ c By increasing the amount of information in each, the estimated maximum friction coefficient μp est The range of possible values ​​becomes smaller, and as shown in Figure 21, the estimated maximum friction coefficient μp is shown by the solid triangle. est The estimation accuracy can be increased. Therefore, the estimated maximum friction coefficient μp, which may have poor accuracy, can be improved. est This avoids the output of the above, and as shown in Figure 21, the estimated maximum friction coefficient μp is obtained with high accuracy. est Because it can output only the maximum friction coefficient μp, it is possible to estimate the maximum friction coefficient μp with high accuracy.

[0176] The other configurations are the same as in the fifth embodiment. The control device 1 of this embodiment can obtain the same effects as those obtained from a configuration similar to or equivalent to that of the fifth embodiment. Although this embodiment is a modification based on the fifth embodiment, it is possible to combine this embodiment with any of the first to fourth embodiments.

[0177] (Other embodiments) While representative embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0178] In the above-described embodiment, an example was explained in which the friction coefficient calculation device is used in a vehicle control system that controls the driving of an electric vehicle and is included in an ECU that controls the rotational speed of the motor for driving the vehicle, but the invention is not limited to this.

[0179] For example, the friction coefficient calculation device may be used in a brake system that controls the braking of a vehicle and may be included in the ECU that controls the brakes. Alternatively, the friction coefficient calculation device may be used as a standalone device and installed in the vehicle. In this case, the friction coefficient calculation device consists of a microcomputer comprising a CPU, ROM, RAM, and other memory, and its peripheral circuits.

[0180] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0181] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0182] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc.

[0183] The control device 1 and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The control device 1 and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The control device 1 and its method of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer in a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0184] 10 Arithmetic section 20 Preservation Department 30 Model Calculation Unit 40 Accuracy determination unit 50 Maximum friction coefficient estimation unit 60 Upper and lower limit extraction section 70 Output determination unit

Claims

1. A friction coefficient calculation device that estimates the maximum friction coefficient, which is the maximum value of the friction coefficient between the tire and the road surface, based on a detection signal transmitted from a detection unit (S) that detects information about the tire when a vehicle is traveling on the road surface, A calculation unit (10) calculates a calculated slip ratio, which is the slip ratio between the tire and the road surface, and a calculated friction coefficient, which is the friction coefficient between the tire and the road surface, based on the detection signal. A storage unit (20) links the information on the calculated slip ratio calculated by the calculation unit with the information on the calculated friction coefficient and stores a set number of items. A model calculation unit (30) obtains multiple brush model characteristics based on a tire brush model that simulates the physical phenomena between the tire and the road surface by setting multiple maximum model friction coefficients, which are the maximum values ​​of the friction coefficient of the brush model formula, and multiple maximum model slip ratios, which are the maximum values ​​of the slip ratio of the brush model formula, and calculates multiple model friction coefficients, which are theoretical estimates of the friction coefficient, using the brush model formula based on the set multiple maximum model friction coefficients and multiple maximum model slip ratios, and the calculated slip ratios of the stored quantity stored in the storage unit, and obtains a model error, which is information regarding the error between the calculated multiple model friction coefficients and the calculated friction coefficients of the stored quantity stored in the storage unit, for each of the multiple brush model characteristics. Based on the model error obtained by the model calculation unit, the accuracy determination unit (40) determines whether each of the multiple maximum model friction coefficients set by the model calculation unit is a high-accuracy maximum friction coefficient that is likely to correspond to the maximum friction coefficient, A maximum friction coefficient estimation unit (50) extracts the model maximum friction coefficient with the smallest value, which is associated with the model error, from among the model maximum friction coefficients determined to be the high-accuracy maximum friction coefficient, as the estimated maximum friction coefficient, which is the estimated value of the maximum friction coefficient. An upper and lower limit extraction unit (60) extracts an upper limit maximum friction coefficient, which is the upper limit of the estimated maximum friction coefficient, and a lower limit maximum friction coefficient, which is the lower limit of the estimated maximum friction coefficient, based on the model error. The system includes an output determination unit (70) that determines whether or not to output the estimated maximum friction coefficient to the outside based on the upper limit maximum friction coefficient and the lower limit maximum friction coefficient. The friction coefficient calculation device, wherein the output determination unit does not output the estimated maximum friction coefficient to the outside if it does not determine that the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to a predetermined determination friction range, and outputs the estimated maximum friction coefficient to the outside if it determines that the difference between the upper limit maximum friction coefficient and the lower limit maximum friction coefficient is less than or equal to the determination friction range.

2. The friction coefficient calculation device according to claim 1, wherein the model calculation unit sets the minimum value of the maximum friction coefficient of the model to 0, sets the maximum value of the maximum friction coefficient of the model to 1, sets the minimum value of the maximum slip ratio of the model to 0, sets the maximum value of the maximum slip ratio of the model to 1, and sets each of the maximum friction coefficient of the model and the maximum slip ratio of the model to any value within the range from the minimum to the maximum value.

3. The friction coefficient calculation device according to claim 1, wherein the upper and lower limit extraction unit extracts the highest value of the model maximum friction coefficients determined by the accuracy determination unit to be the high-accuracy maximum friction coefficient as the upper limit maximum friction coefficient, and extracts the lowest value of the model maximum friction coefficients determined by the accuracy determination unit to be the high-accuracy maximum friction coefficient as the lower limit maximum friction coefficient.

4. The model calculation unit calculates the model error for each brush model characteristic by calculating the error between the calculated friction coefficient associated with each of the multiple calculated slip ratios and the model friction coefficient obtained from each of the multiple calculated slip ratios, and then summing up the respective calculated errors. The friction coefficient calculation device according to claim 1, wherein the accuracy determination unit determines whether the set number of maximum friction coefficients of the model is the high-accuracy maximum friction coefficient, based on whether the model error is smaller than a predetermined determination threshold.

5. The friction coefficient calculation device according to claim 1, wherein the model calculation unit sets the maximum model friction coefficient set for obtaining the brush model characteristics to a value greater than or equal to the calculated friction coefficient, and sets the maximum model slip ratio set for obtaining the brush model characteristics to a value greater than or equal to the calculated slip ratio.

6. The model calculation unit calculates the model error for each brush model characteristic by calculating the error between the calculated friction coefficient associated with each of the multiple calculated slip ratios and the model friction coefficient obtained from each of the multiple calculated slip ratios, and then summing up the respective calculated errors. The friction coefficient calculation device according to claim 1, wherein the accuracy determination unit determines whether the set of multiple model maximum friction coefficients is the high-accuracy maximum friction coefficient, based on whether the model error is smaller than a predetermined determination threshold set based on the difference between the maximum and minimum values ​​of the model error.

7. The model calculation unit calculates the model error for each brush model characteristic by calculating the error between the calculated friction coefficient associated with each of the multiple calculated slip ratios and the model friction coefficient obtained from each of the multiple calculated slip ratios, and then summing up the respective calculated errors. The friction coefficient calculation device according to claim 1, wherein the upper and lower limit extraction unit extracts a predetermined number of the model errors in ascending order of value, extracts the highest-accuracy maximum friction coefficient with the largest value among the high-accuracy maximum friction coefficients associated with each of the extracted predetermined number of model errors as the upper limit maximum friction coefficient, and extracts the lowest-value high-accuracy maximum friction coefficient among the high-accuracy maximum friction coefficients associated with each of the extracted predetermined number of model errors as the lower limit maximum friction coefficient.

8. When the storage unit sets the control process for storing the calculated slip ratio information and the calculated friction coefficient information as a storage process, if the output determination unit does not output the estimated maximum friction coefficient to the outside, the storage quantity in the next storage process will be set to be greater than the storage quantity set in the previous storage process, and the calculation unit will further acquire the calculated slip ratio information and the calculated friction coefficient information from the calculation unit, thereby storing more of the calculated slip ratio information and the calculated friction coefficient information than the quantity stored in the previous storage process. The model calculation unit then recalculates the model error using the calculated slip rate and calculated friction coefficient of the stored quantity that are greater than the calculated slip rate and calculated friction coefficient of the stored quantity stored in the previous storage process. The accuracy determination unit, based on the model error obtained by the model calculation unit, re-determines whether the model's maximum friction coefficient is the high-accuracy maximum friction coefficient. The maximum friction coefficient estimation unit extracts an estimated maximum friction coefficient again from the model maximum friction coefficient which has been determined to be the high-accuracy maximum friction coefficient. The upper and lower limit extraction unit extracts the upper limit maximum friction coefficient and the lower limit maximum friction coefficient again. The friction coefficient calculation device according to claim 1, wherein the output determination unit determines again whether or not to output the estimated maximum friction coefficient to the outside.

9. The friction coefficient calculation device according to claim 8, wherein, if the output determination unit does not output the estimated maximum friction coefficient to the outside, the storage unit further acquires the calculated slip ratio information and the calculated friction coefficient information from the calculation unit during a set predetermined elapsed time in the next storage process, thereby increasing the quantity of the calculated slip ratio information and the calculated friction coefficient information to be stored in the next storage process to the quantity stored in the previous storage process.

10. The friction coefficient calculation device according to claim 8, wherein, if the output determination unit does not output the estimated maximum friction coefficient to the outside, in the next saving process, the storage unit further acquires the calculated slip ratio information and the calculated friction coefficient information from the calculation unit while the vehicle travels a set predetermined distance, thereby increasing the quantity of the calculated slip ratio information and the calculated friction coefficient information to be saved in the next saving process to the quantity saved in the previous saving process.

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