Ground load estimation device, control device and ground load estimation method

Abstract

Ground contact load estimator (100) for estimating a ground contact load of a vehicle (900), the ground contact load estimator comprising: a sensing section configured to receive as a physical quantity relating to the vehicle (900) a value from a longitudinal acceleration sensor (340) that detects the longitudinal acceleration of the vehicle (900), a value from a lateral acceleration sensor (131) that detects the lateral acceleration of the vehicle (900), a value from a wheel speed sensor (133) that detects a wheel angular velocity of the vehicle (900), a value from a cornering information sensor that detects cornering information of the vehicle (900), a mass of the vehicle (900), a center of mass height of the vehicle (900), a rolling moment of inertia, a pitching moment of inertia, a front axle intermediate center of gravity distance of the vehicle (900), and a rear axle intermediate center of gravity distance. of the vehicle (900),to record a front tread length of the vehicle (900) and a rear tread length of the vehicle (900); and- an inertial load estimation section (110), comprising: (i) a reference inertial load calculation section configured to calculate a reference inertial load according to a model of the vehicle (900) using the longitudinal acceleration sensor value (340), the lateral acceleration sensor value (131), the wheel speed sensor value (133), the vehicle mass (900), the vehicle center of mass height (900), the rolling moment of inertia, the pitching moment of inertia, the vehicle front axle intermediate center of gravity distance (900), the vehicle rear axle intermediate center of gravity distance (900), the front tread length and the rear tread length, each as acquired by the acquisition section, and (ii) a correction value calculation section (112) configured toto calculate an inertial load correction value using the mass of the vehicle (900), the center of mass height of the vehicle (900), the wheel speed sensor value (133), the cornering information sensor value, the rolling moment of inertia, the front tread length and the rear tread length, each acquired by the sensing section, wherein the inertial load estimation section (110) is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load, where the inertial load means a variation in the ground contact load due to the effect of the vehicle cornering (900) and the effect of the vehicle accelerating / decelerating (900).

Description

technical field

[0001] The present invention relates to a ground contact load estimation device, a control device, and a ground contact load estimation method. General state of the art

[0002] A technique is known to those skilled in the art in which a ground contact load on a wheel of a vehicle is estimated and a result of the estimation is used to control a braking force and a driving force of the vehicle so that running stability of the vehicle is improved. The ground contact load needs to be estimated with a sufficiently high accuracy in order to improve the driving stability of the vehicle. Examples of a known technique for estimating ground contact load include a technique in which (i) a roll angular velocity detected by a roll rate sensor and (ii) a pitch angular velocity detected by a pitch rate sensor are used to estimate a ground contact load (see Patent Literature 1, for example). Citation list [patent literature]

[0003] [Patent Literature 1] Japanese Patent Application Publication Tokukai No. 2013-216278 Summary of the invention Technical problem

[0004] However, such a technique as described above known to those skilled in the art requires more sensors required for estimating the ground contact load, such as the roll rate sensor and the pitch rate sensor. This can lead to an increase in costs. The technology known to the person skilled in the art can therefore still be improved, at least from the point of view of reducing the sensor-related costs.

[0005] An aspect of the present invention is an object of providing a technique that not only makes it possible to reduce sensor-related costs but also makes it possible to estimate a ground contact load of a vehicle with sufficiently high accuracy. the solution of the problem

[0006] In order to achieve the object, a ground contact load estimating device according to an aspect of the present invention is a ground contact load estimating device for estimating a ground contact load of a vehicle, the ground contact load estimating device including: a detecting section configured to detect a physical quantity related to the to capture vehicle; and an inertial load estimating section including: (i) a reference inertial load calculating section configured to calculate a reference inertial load using the physical quantity detected by the detecting section, and (ii) a correction value calculating section configured to calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load.

[0007] Furthermore, to achieve the object, a control device according to an aspect of the present invention is a control device for estimating a ground contact load acting on a vehicle and for directly or indirectly using the ground contact load to control one or more other devices of the vehicle, the control device includes: a detection section configured to detect a physical quantity related to the vehicle; and an inertial load estimating section including: (i) a reference inertial load calculating section configured to calculate a reference inertial load using the physical quantity detected by the detecting section, and (ii) a correction value calculating section configured to calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load.

[0008] Furthermore, to achieve the object, a ground contact load estimation method according to an aspect of the present invention is a ground contact load estimation method for estimating a ground contact load of a vehicle, the ground contact load estimation method comprising the steps of: detecting a physical quantity relating to the vehicle relates; calculating a reference inertial load using the detected physical quantity; calculating an inertial load correction value using the detected physical quantity; and estimating an inertia load by adding the inertia load correction value to the reference inertia load. Advantageous Effects of the Invention

[0009] An aspect of the present invention makes it possible to estimate a ground contact load of a vehicle with sufficiently high accuracy using a sensor that is widely used to control driving of the vehicle. It is therefore possible to reduce sensor-related costs and also to estimate a ground contact load of a vehicle with sufficiently high accuracy. character list figure 1 is a block diagram illustrating an example of a functional configuration of a ground contact load estimation device according to Embodiment 1 of the present invention. figure 2 is a block diagram illustrating an example of a functional configuration of an inertial load estimation section of Embodiment 1 of the present invention. figure 3 is a block diagram illustrating an example of a functional configuration of a reference inertial load calculation section of Embodiment 1 of the present invention. figure 4 is a view for describing a physical quantity related to rolling behavior of a vehicle body. figure 5 is a view for describing a physical quantity related to a pitching behavior of a vehicle body. figure 6 is a view for describing a roll angular acceleration around the center of mass of a vehicle body. figure 7 is a view for describing a turning radius of a vehicle. figure 8 is a block diagram illustrating an example of a functional configuration of a road surface load estimating section of Embodiment 2 of the present invention. figure 9 is a view for describing a physical quantity related to a wheel of a vehicle. figure 10 is a view schematically illustrating an example of a configuration of a vehicle to which a ground contact load estimation device according to an embodiment of the present invention is applied. Description of Embodiments

[0010] According to an embodiment of the present invention, a ground contact load on a wheel of a vehicle is estimated with sufficiently high accuracy with reference to a physical quantity of the vehicle, which physical quantity can be detected using a sensor commonly used to execute control for improving driving stability of the vehicle is used. It should be noted that the phrase “referring to a physical quantity” is a general term used herein for direct or indirect use of the physical quantity and as used herein means direct and / or indirect use of the physical quantity. [Ground Contact Load Estimator]

[0011] A ground contact load estimation device according to an embodiment of the present invention estimates a ground contact load of a vehicle. The ground contact load estimating device includes a detecting section and an inertial load estimating section. [capture section]

[0012] The detection section is a device for detecting a physical quantity related to a vehicle. The detection section transmits the physical quantity to the inertial load estimation section (described later) and a correction value calculation section (described later). Examples of the detection section include various sensors and a device for calculating and outputting the physical quantity.

[0013] According to the present embodiment, a sensor may be a commonly used sensor (hereinafter also referred to as a “universal sensor”) to perform standard control related to the operation of a vehicle. The sensor does not necessarily have to include a roll rate sensor and a pitch rate sensor. Examples of the sensor (universal sensor) serving as the detection section include a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, a lateral acceleration sensor that detects the lateral acceleration of the vehicle, a wheel speed sensor that detects the wheel angular speed of the vehicle, and a cornering information sensor that detects Vehicle cornering information captured. Examples of the cornering information sensor include a yaw rate sensor and a steering angle sensor.

[0014] Examples of the physical quantity mentioned above include a longitudinal acceleration sensor value, a lateral acceleration sensor value, a wheel speed sensor value, a cornering information sensor value, a mass of the vehicle, a center of gravity height of the vehicle, a rolling moment of inertia, a pitching moment of inertia, a front axle inter-center of gravity distance of the vehicle , a rear axle center of gravity distance of the vehicle, a front tread length of the vehicle, and a rear tread length of the vehicle. [Inertial Load Estimation Section]

[0015] The inertial load estimation section includes a reference inertial load calculation section and a correction value calculation section. The inertial load estimation section estimates an inertial load by adding an inertial load correction value calculated by the correction value calculation section to a reference inertial load calculated by the reference inertial load calculation section. The “inertial load” means a change in ground contact load due to the effect of cornering of the vehicle and an effect of accelerating / decelerating the vehicle. The reference inertial load calculation section calculates the reference inertial load using the physical quantity detected by the detection section. The reference inertial load means a solution of an equation (described later) representing the inertial load of the vehicle. The inertia load correction value is a correction value for correcting the reference inertia load such that a difference between the reference inertia load and a true inertia load is reduced.

[0016] According to the present embodiment, the physical quantity used to calculate the reference inertial load may be a physical quantity detected by a universal sensor (as described above) and may be a physical quantity specific to the vehicle. For example, the reference inertial load calculation section may calculate the reference inertial load on each wheel of the vehicle according to a model of the vehicle using the value of the longitudinal acceleration sensor, the value of the lateral acceleration sensor, the mass of the vehicle, the center of mass height of the vehicle, the rolling moment of inertia, the pitching moment of inertia, the front axle Calculate the vehicle intercenter distance, the rear axle intercenter distance of the vehicle, the front tread length, and the rear tread length.

[0017] It should be noted here that the "model of the vehicle" is a model that allows the calculation of the reference inertial load. The model can suitably be determined according to a mathematical expression for calculating the reference inertial load. For example, the model of the vehicle may be a model of a solution of an equation of motion represented by a linear system, the solution being obtained by applying a minimum norm solution.

[0018] The correction value calculation section calculates the inertial load correction value using the physical quantity detected by the detection section. The physical quantity used by the correction value calculation section to calculate the inertial load correction value may also be a physical quantity detected by a universal sensor and a physical quantity specific to the vehicle, as before described. For example, the correction value calculation section can calculate the inertial load correction value using the mass of the vehicle, the center of mass height of the vehicle, the value of the wheel speed sensor, the value of the cornering information sensor, the rolling moment of inertia, the front tread length, and the rear tread length. The value of the cornering information sensor can expediently be a value of the yaw rate sensor or a value of the steering angle sensor. [Road Surface Load Estimation Section]

[0019] The ground contact load estimation device of the present embodiment may have another configuration as long as the effects of the present invention can be realized. For example, the ground contact load estimation device may further include a road surface load estimation section configured to estimate a road surface load of the vehicle.

[0020] The “road surface load” means a change in ground contact load due to an impact of the road surface such as unevenness of the road surface. In order to reduce the cost of the detecting section (e.g., a sensor) for estimating the road surface load, the road surface load estimating section is preferably configured to detect the road surface load using the physical quantity detected by a universal sensor and the physical quantity used for the Vehicle specific is appreciated. However, it should be noted that the configuration of the road surface load estimating section is not limited to this. For example, the road surface load estimating section preferably estimates the road surface load by multiplying an effective tire radius variation (described below) by a first gain. In this case, the detection section (as described above) preferably includes a wheel speed sensor that detects the wheel angular speed of the vehicle, and is preferably a device for detecting the physical quantity including the wheel angular speed, a stable load of the vehicle, and an inertial load of the vehicle.

[0021] The road surface load estimation section includes a first-gain calculation section and an effective tire radius variation calculation section. The first-gain calculation section calculates the first gain from at least the stable load of the vehicle and the inertial load of the vehicle. The first gain is at least one parameter indicative of the stiffness of a wheel (e.g., a tire) of the vehicle. The first gain is a value unique to a wheel. As will be described later, the first gain can be determined from an equation that essentially represents the stiffness of the wheel to which a specific ground contact load is applied.

[0022] The tire effective radius variation calculation section calculates the variation of an effective tire radius by multiplying a variation of a wheel angular velocity by a second gain. The variation of an effective tire radius is a value representing a variation of the radius of a tire due to an influence of the road surface using a variation of the wheel speed. The variation in a wheel angular velocity can be determined from a result of detection by the wheel velocity sensor. Basically, the variation in wheel angular velocity need only represent a variation in wheel angular velocity caused during a step of estimating a ground contact load, and may be an approximation of the variation.

[0023] The second gain is a parameter for reducing the influence of the variation in wheel angular velocity on the estimation result. In general, when estimating a state quantity of the vehicle (for example, a ground contact load of the vehicle), a result of the estimation and an actual driving state tend to deviate more from each other the more a condition related to actual driving of the vehicle from a predetermined condition related to a usual one driving the vehicle. The second gain can be determined by - for example by experiment or simulation - deriving an appropriate numerical value such that an estimated value of the ground contact load substantially corresponds to a measured actual value of the ground contact load of the vehicle under various conditions relevant to the driving the vehicle are assumed to be identical.

[0024] The road surface load estimating section may have another configuration as long as the benefits of the present embodiment can be realized. For example, the road surface load estimation section may further include a second-gain correction section.

[0025] The second gain correcting section calculates a slip ratio related value of the vehicle from the wheel speed sensor value to correct the second gain according to at least the slip ratio related value and a jerk of the vehicle. In this case, the detecting section further detects the jerk of the vehicle. The jerk movement can be detected, for example, by an acceleration sensor. [Method of Estimating Ground Contact Load]

[0026] According to the present embodiment, a ground contact load of a vehicle can be estimated by a method including the steps of: acquiring a physical quantity related to the vehicle; calculating a reference inertial load using the physical quantity detected by the detecting section; calculating an inertial load correction value using the physical quantity detected by the detecting section; and calculating an inertia load by adding the inertia load correction value to the reference inertia load. The method of estimating the ground contact load of the vehicle may be performed using the ground contact load estimator (as described above).

[0027] According to the present embodiment, an estimated value of the ground contact load of the vehicle is obtained by adding together (i) the inertial load estimated by the inertial load estimating section and (ii) the stable load of the vehicle. The stable load is a ground contact load at 1G of the vehicle. For example, the stable load may be a calculated value based on the mass of the vehicle or may be a constant specific to the vehicle. In a case where the ground contact load estimating device further includes the road surface load estimating section, an estimated value of the ground contact load of the vehicle can be obtained by (i) the inertial load estimated by the inertial load estimating section, (ii) the inertial load estimated by the road surface load estimating section estimated road surface load, and (iii) the stable load are added together. [control device]

[0028] A control device of an embodiment of the present invention estimates a ground contact load acting on a vehicle, and directly or indirectly uses the ground contact load to control one or more other devices of the vehicle. The control device of the present embodiment can be configured as in the case of a publicly known device for controlling one or more devices of the vehicle according to a ground contact load, except that the control device includes the ground contact load estimation device (described above). Note that a case where the ground contact load is used indirectly includes, for example, a configuration in which the estimated ground contact load is used to perform further estimation and a value of a result of the further estimation is used to generate one or to control several other devices.

[0029] An embodiment of the present invention is concretely described below. [Embodiment 1: First embodiment of ground contact load estimation apparatus]. [Functional Configuration of Ground Contact Load Estimation Device]

[0030] figure 1 is a block diagram illustrating an example of a functional configuration of a ground contact load estimation device according to Embodiment 1 of the present invention. As in figure 1, a ground contact load estimating device 100 includes an inertial load estimating section 110, a road surface load estimating section 120, a longitudinal acceleration sensor and a lateral acceleration sensor (longitudinal and lateral acceleration sensors) 131, a steering angle sensor or yaw rate sensor (steering angle / yaw rate sensor) 132, a wheel speed sensor 133, a stable load providing section 141, a delay section 142, and adding sections 143 and 144.

[0031] The longitudinal and lateral acceleration sensor 131, the steering angle / yaw rate sensor 132 and the wheel speed sensor 133 are connected to the inertial load estimating section 110. FIG. The longitudinal and lateral acceleration sensor 131 and the wheel speed sensor 133 are connected to the road surface load estimating section 120 . The longitudinal and lateral acceleration sensor 131, the steering angle / yaw rate sensor 132 and the wheel speed sensor 133 (i) provide a physical quantity related to a vehicle to be detected by the inertial load estimation section 110 and (ii) serve as one Detecting section related to the inertial load estimating section 110.

[0032] The inertial load estimating section 110 outputs a calculated inertial load signal. The inertial load estimating section 110 is connected to the adding section 143 via the delay section 142 . The steady load providing section 141 outputs a steady load signal. The stable load providing section 141 is also connected to the adding section 143 . The adding section 143 is connected to both the adding section 144 and the road surface load estimating section 120 . The road surface load estimating section 120 is connected to the adding section 144 .

[0033] The longitudinal and lateral acceleration sensor 131, the steering angle / yaw rate sensor 132, the wheel speed sensor 133, the stable load providing section 141 and the inertial load estimating section 110 (i) provide the physical quantity related to the vehicle and through the road surface load estimating section 120 to be detected, and (ii) serve as a detecting section with respect to the road surface load estimating section 120.

[0034] In addition, the inertial load estimating section 110 and the road surface load estimating section 120 are each connected to a network of a control system of the vehicle (for example, CAN (described later)), which is not illustrated here. The inertial load estimating section 110 and the road surface load estimating section 120 detect the physical quantity specific to the vehicle, such as a mass of the vehicle, a center of mass height of the vehicle, a rolling moment of inertia with respect to a point via such a network a road surface corresponding to the vehicle's center of mass, a pitching moment of inertia measured with respect to the point on the road surface, a front axle inter-centre of gravity distance, a rear axle inter-centre of gravity distance, a front tread length, and a rear tread length. The network also corresponds to a detection section of Embodiment 1.

[0035] figure 2 is a block diagram illustrating an example of a functional configuration of an inertial load estimation section of Embodiment 1 of the present invention. As in figure 2 illustrates, the inertial load estimation section 110 includes a reference inertial load calculation section 111 and a correction value calculation section 112.

[0036] figure 3 is a block diagram illustrating an example of a functional configuration of a reference inertial load calculation section of Embodiment 1 of the present invention. As in figure3 illustrates, the reference inertial load calculation section 111 includes a system matrix section 301, an input matrix section 302, an adder section 303 and a delay section 304. The system matrix section 301 is connected to the adder section 303, the adder section 303 is connected to the delay section 304, and the delay section 304 is connected to the system matrix section 301. The input matrix section 302 is connected to an outside such as the network (described above) and is connected to the adding section 303 .

[0037] The road surface load estimating section 120 is constituted by a publicly known road surface load estimating apparatus. For example, the road surface load estimating section 120 is a device for estimating the road surface load from, for example, an image picked up by a camera (not illustrated). [Logic of Ground Contact Load Estimation]

[0038] A ground contact load of Embodiment 1 is represented by Equation (1) below. In Equation (1), F z0nom represents the ground contact load in a 1G state, dF z0,inertia represents the inertial load, and dF z0,road represents the road surface load. As described above, the "inertial load" means a variation in ground contact load due to an effect of cornering of the vehicle and an effect of acceleration / deceleration of the vehicle, and the "road surface load" means a variation in ground contact load due to an effect of the road surface , such as an unevenness in the road surface. F z 0 = F z 0 n o m + d F z 0, i n e r t i a + d F z 0, r o a d

[0039] figure 4 is a view for describing a physical quantity related to rolling behavior of a vehicle body. figure 5 is a view for describing a physical quantity related to a pitching behavior of a vehicle body. figure 6 is a view for describing a roll angular acceleration around the center of mass of a vehicle body.

[0040] dF z0.inertia is represented by three equations of motion of Equations (2A), (2B) and (2C) below. Equation (2A) represents movement in a vertical direction, Equation (2B) represents roll behavior, and Equation (2C) represents pitch behavior. Referring to the position of a wheel, front, rear, right and left are used herein labeled “f” (front), “r” (rear), “r” (right) and “I” (left). In terms of a direction with respect to the vehicle, a longitudinal direction, a lateral direction, and the vertical direction are expressed as “x”, “y” and “z”, respectively. d F z 0 f l + d F z 0 f r + d F z 0 r l + d F z 0 r r = m a z t r f ( d F z 0 f l − d F z 0 f r ) + t r r ( d F z 0 r l − d F z 0 r r ) = ( l x + l 1 ) p ˙ − m a y h 0 − l f ( d F z 0 f l + d F z 0 f r ) + l r ( d F z 0 r l − d F z 0 r r ) = ( l y + l 2 ) q ˙ + m a x h 0

[0041] As in the figure 4 and figure 5, m represents the mass of the vehicle, ho represents the center of mass height of the vehicle, a x represents the longitudinal acceleration of the vehicle, a y represents the lateral acceleration of the vehicle, and a z represents the vertical acceleration of the vehicle. I 1 and I 2 represent correction values ​​for calculating moments of inertia about road surface points using moments of inertia about axes passing through respective centers of mass COG1 and COG2. The center of mass COG1 represents a center of mass in the width direction of a vehicle body 200, and the center of mass COG2 represents a center of mass in the longitudinal direction of the vehicle body 200.

[0042] As in figure 4 illustrates, furthermore (I x +I 1 ) represents the rolling moment of inertia about the road surface point, I x represents the moment of inertia about the roll axis passing through the center of mass COG1, trr represents half the length of a rear tread of the vehicle (the length of the rear tread multiplied by 1 / 2), and trf represents half the length of a front tread of the vehicle ( the length of the front tread multiplied by 1 / 2). The p with the dot above it (p - dot) represents the roll angular acceleration around the road surface point.

[0043] As in figure5 illustrates, furthermore (I y +I 2 ) represents the pitching moment of inertia about the road surface point, and I y represents the moment of inertia about the pitch axis passing through the center of mass COG2. I f represents a longitudinal distance between the center of mass COG2 and a front axle of the vehicle body 200, I r represents a distance between the center of mass COG2 and a rear axle, and (I f +I r ) represents a wheelbase. The q with the dot above it represents the pitch angular acceleration around the road surface point.

[0044] Assuming that dF est (k) is a calculated value of the variation in ground contact load at a certain point in time, its vector is illustrated by Equation (3) below. In the following equation (3), k represents the frequency of calculation. d F e s t ( k ) → = d F z 0 ( k ) → = [ d F z 0 f l d F z 0 f r d F z 0 r l d F z 0 r r ] T

[0045] A matrix into which Equations (2A) to (2C) are transformed is represented by Equation (4) below, and Equation (5) below is derived from Equation (4). A 3×3 matrix on the right side of Equation (5) is also referred to as a matrix K', and a 3×1 matrix in parentheses on the right side of Equation (5) is also referred to as a matrix a'. [ 1 1 1 − t r f t r r − t r r − l f l r l r ] [ d F z 0 f r d F z 0 r l d F z 0 r r ] = [ m a z ( l x + l 1 ) p ˙ − m a y h 0 ( l y + l 2 ) q ˙ + m a x h 0 ] = [ 1 t r f − l f ] d F z 0 f l [ d F z 0 f r d F z 0 r l d F z 0 r r ] = <menclose notation="box"> [ l r l f + l r 0 − 1 l f + l r l f t r r + l r t r f 2 t r r ( l f + l r ) 1 2 t r r − t r f − t r r 2 t r r ( l f + l r ) l f t r r − l r t r f 2 t r r ( l f + l r ) − 1 2 t r r t r f + t r r 2 t r r ( l f + l r ) ] < / menclose> K ' ( [ m a z ( l x + l 1 ) p ˙ − m a y h 0 ( l y + l 2 ) q ˙ + m a x h 0 ] − <menclose notation="box"> [ 1 t r f − l f ] < / menclose> a ' d F z 0 f l )

[0046] If we assume here that “dF z0fl " is "Z", Equation (3) is represented by Equation (6) below. Z is a variable that satisfies equations (2A) to (2C). A 4×1 matrix in the first term on the right-hand side of Equation (6) represents a vector a. A 4×3 matrix in the second term on the right-hand side of Equation (6) is also referred to as a matrix K, and a 3×1 matrix in this term is also called a matrix U. The vector a is represented by a matrix of Equation (7) using the matrix K' and the matrix a' in Equation (5). The matrix K in Equation (6) is represented by a matrix of Equation (8) using the matrix K' in Equation (5). d F e s t ( k ) → = [ d F z 0 f l d F z 0 f r d F z 0 r l d F z 0 r r ] = <menclose notation="box"> [ 1 − 1 − t r f t r r t r f t r r ] < / menclose> a → Z + <menclose notation="box"> <menclose notation="box"> [ 0 0 0 l r l f + l r 0 − 1 l f + l r l f t r r + l r t r f 2 t r r ( l f + l r ) 1 2 t r r − t r f − t r r 2 t r r ( l f + l r ) l f t r r − l r t r f 2 t r r ( l f + l r ) − 1 2 t r r t r f + t r r 2 t r r ( l f + l r ) ] < / menclose> K <menclose notation="box"> [ m a z ( l x + l 1 ) p ˙ − m a y h 0 ( l y + l 2 ) q ˙ + m a x h 0 ] < / menclose> U < / menclose> d F e s t , p → a → = [ 1 − K ' a ' ] K = [ 0 K ' ]

[0047] Assuming that a vector dF est,p is the product of the matrix K and the matrix U on the right side of Equation (6), Equation (6) is represented by Equation (9) below. dF est,p represents an arbitrary solution of equations (2A) to (2C). The equations of motion (2A) to (2C) (described previously) are thus represented by equation (9). That is, the solution of the equations of motion (2A) to (2C) is represented by a linear equation, and a calculated value of the ground contact load to be found is present in one of the straight lines represented by the linear equation. d F e s t ( k ) → = d F e s t , p → + a → Z <anwendung der minimum-norm-lösung>

[0048] In the equations of motion (2A) to (2C) there are four variables (dF z0fl , dF z0fr , dF z0rl and dF z0rr ), and there are three equations related to these variables. In view of this, a minimum norm solution is applied to equation (9). A condition represented by expression (10) below, that is, a value of a solution included in solutions of the equations of motion and whose difference from a previously calculated value of the variation in ground contact load is minimized is given as a solution of equation (9 ) Are defined. In expression (10), dF est (k-1) represents the previously calculated value of ground contact load. dF est,p represents one of the solutions of the equations of motion. Minimize ‖ d F e s t ( k − 1 ) → − d F e s t ( k ) → ‖

[0049] Applying the above definition allows Equation (11) to be derived from Equation (9) as shown below. In Equation (11), the "â" represents a unit vector of the vector a. d F e s t ( k ) → = d F e s t , p → + a → z = d F e s t , p → + a → | a → | ( ( d F e s t ( k − 1 ) → − d F e s t , p → ) ⋅ a ^ ) = d F e s t , p → + a → | a → | 2 ( ( d F e s t ( k − 1 ) → − d F e s t , p → ) ⋅ a → ) <lineare modellierung>

[0050] Equation (11), which is expressed by a linear model, is represented by Equation (12) below and is further represented by Equation (13). d F e s t ( k ) → = <menclose notation="box"> ( a a T | a → | 2 ) < / menclose> A d F e s t ( k − 1 ) → + <menclose notation="box"> ( I − a a T | a → | 2 ) K < / menclose> B U d F e s t ( k ) → = A d F e s t ( k − 1 ) → + B U

[0051] In the above equations, U represents an input value, A represents a system matrix, and B represents an input matrix. The vector dF est,p is represented by the product of the matrix K and the matrix U as shown below. The matrix K and the matrix U are represented as shown below, and A and B are each represented using a matrix as shown below. d F e s t , p → = K U K = [ 0 0 0 l r l f + l r 0 − 1 l f + l r l f t r r + l r t r f 2 t r r ( l f + l r ) 1 2 t r r − t r f − t r r 2 t r r ( l f + l r ) l f t r r − l r t r f 2 t r r ( l f + l r ) − 1 2 t r r t r f + t r r 2 t r r ( l f + l r ) ] U = [ m a z ( l x + l 1 ) p ˙ − m a y h 0 ( l y + l 2 ) q ˙ + m a x h 0 ] A = a a T | a → | 2 = 1 2 ( t r f 2 + t r r 2 ) [ t r r 2 − t r r 2 − t r f t r r t r f t r r − t r r 2 t r r 2 t r f t r r − t r f t r r − t r f t r r t r f t r r t r f 2 − t r f 2 t r f t r r − t r f t r r − t r f 2 t r f 2 ] B = ( I − a a T | a → | 2 ) K = 1 2 [ l r l f + l r t r f t r f 2 + t r r 2 − 1 l f + l r l r l f + l r − t r f t r f 2 + t r r 2 − 1 l f + l r l f l f + l r t r r t r f 2 + t r r 2 1 l f + l r l f l f + l r − t r r t r f 2 + t r r 2 1 l f + l r ]

[0052] The variable dF to be determined est (k) can be obtained by substituting the matrix U in equation (13) (described earlier) which is the linear model. <berechnung des korrekturwertes>

[0053] The matrix U contains the vertical acceleration a z , the roll angular acceleration p-point and the pitch angular acceleration q-point which are not calculated from a detected value of the universal sensor (described earlier). A solution to equation (13) can be found by substituting a given value (e.g. zero) into these accelerations. In addition, however, it is necessary to consider the influence of a z , p-point and q-point to correct.

[0054] The "dF est (k) " is also referred to as a "reference inertial load" hereinafter, and a correction value for correcting the influence of a z , p-point and q-point is also referred to as an "inertial load correction value" hereinafter, and is represented by "dF Z0,corr " shown. "dF Z0,inertia ", which is an inertia load to be detected, is represented by Equation (14) below. Note that an initial value dF est (0) of the reference inertia load is set to "0". d F z 0, i n e r t i a → = d F e s t ( k ) → + d F z 0, c o r r → (Correction of the influence of roll angular acceleration (p-point))

[0055] The inertia load correction value can be calculated using a convenient equation that takes into account the magnitude and frequency of the influence of a z , p-point and q-point can be calculated using a physical quantity that can be detected by the universal sensor. For example, the inertia load correction value dF Z0,corr represented by equation (15) below. In Equation (15), K p represents an adjustment parameter, and ΣF y0 represents the total sum of tire lateral forces measured while the vehicle is rolling. A vector p is represented by Equation (16). A part (except ΣF y0 ) of the right side of equation (15) corrects the influence of p-point and is important when the vehicle is cornering. For example, K p are determined by (i) comparing (a) an actual measured value of the ground contact load of the cornering vehicle with (b) an estimated value of the ground contact load estimated using equation (15), and (ii) adjusting appropriately by K p such that the estimated value is effective substantially even under a condition different from a running condition of the vehicle subjected to the measurement of the actual measured value. d F z 0, c o r r → = ∑ F y 0 ⋅ K p ( h 0 t r r 2 ( t r f 2 + t r r 2 ) ) ( 1 + l 1 l x ) p → p → = [ t r f t r r − t r f t r r 1 − 1 ] T

[0056] Note here that the influence of p-point, which is expressed as "e p-point", is represented by equation (17) below. The left side of equation (17) is "e p-point", what is the influence of p - point. The 3×1 matrix by which B is multiplied in equation (17) is a matrix in which a x , a y , a z and q-point in the matrix U (described previously) are all set to zero. e p ˙ = B [ 0 ( l x + l 1 ) p ˙ 0 ] = ( ( l x + l 1 ) t r r 2 ( t r f 2 + t r r 2 ) ) p ˙ <menclose notation="box"> [ t r f t r r − t r f t r r 1 − 1 ] < / menclose> p ˙ = ( ( l x + l 1 ) t r r 2 ( t r f 2 + t r r 2 ) ) p ˙ p →

[0057] It should be noted here that figure 6 is a view for describing a roll angular acceleration around the center of gravity of a vehicle body. As in figure 6 illustrates, puts p-dot in figure 6 represents a roll angular velocity around the center of mass COG1 of the vehicle body. This p-point around the center of mass of the vehicle body is represented by equation (18) below. The product of matrices on the right-hand side of equation (18) is so tiny that it is negligible and can therefore be taken as a zero. I x p ˙ = ∑ F y 0 h 0 + [ t r f − t r f t r r − t r r ] [ F z 0 f l F z 0 f r F z 0 r l F z 0 r r ]

[0058] ΣF y0 is represented by equation (19). It should be noted here that figure 7 is a view for describing a turning radius in relation to an actual steering angle of a vehicle. figure 7 illustrates a case where the vehicle is turning left. figure 7 illustrates cornering of the vehicle steered only by the front wheels. In figure 7, C is a curve center and O is a wheel center. "R turn " represents a curve radius and is a distance from the curve center C and the center of mass COG3 of the vehicle. "R t , rn , l " represents a distance from the curve center C in the width direction of the vehicle body to an intersection O of the wheel on the left side of the vehicle, and "Rt urn,r " represents a distance from the cornering center C in the width direction of the vehicle body to an intersection O of the wheel on the right side of the vehicle. δ is the actual steering angle.

[0059] A V fl vector and a V fr -Vector are driving direction vectors at front wheel points, and β fl and β fr are front wheel slip angles. β fl is represented by an angle formed by the V fl -Vector with respect to a line Lω fl is formed, and β fr is represented by an angle formed by the V fr -Vector with respect to a line Lω fr is formed. A dashed line Lω fl is a line extending in a rolling direction of the wheel, and is a straight line passing through a center O fl of the wheel runs. A dashed line Lω fr is a line extending in the rolling direction of the wheel, and is a straight line passing through a center O fr of the wheel runs. A V rl vector and a V rr -Vector are directional vectors at rear wheel points. β rl and ß rr are rear wheel slip angles and are represented by angles divided by the V rr -Vector or the V rr -vector with respect to the longitudinal direction of the vehicle body 200 can be formed. In a case where the vehicle is steered by both the front wheels and the rear wheels, β fl and β fr suitably corrected taking into account the steering by the rear wheels.

[0060] Given the fact that "R turn ‟ in Equation (19) is represented by Equation (20), Equation (19) is represented by Equation (21). "R turn " will be described later. In Equation (21) below, "u" is an average of the peripheral speeds of all the wheels and is represented by Equation (22). In Equation (22), ω represents the angular velocity of the wheel, and "R e , i n it" represents an initial value of the effective tire radius. "δ" is represented by equation (23). In Equation (23), δs represents a detected value of the steering angle sensor, and k δ represents the steering gear ratio. ∑ F y 0 = m u 2 R t u r n R t u r n ≈ l f + l r δ ∑ F y 0 = m u 2 δ l f + l r u = a v g ( ω R e , i n i t ) δ = k δ δ S

[0061] Thus, assuming that the influence of p-dot is "e p-dot", "e p-dot" is represented by the following equation (24). e p ˙ = ( ( l x + l 1 ) t r r 2 ( t r f 2 + t r r 2 ) ) p ˙ p → = ( ( l x + l 1 ) t r r 2 ( t r f 2 + t r r 2 ) ) ( h 0 l x ) ∑ F y 0 = ( h 0 t r r 2 ( t r f 2 + t r r 2 ) ) ( 1 + l 1 l x ) ∑ F y 0

[0062] Equation (20) is described here. R turn,I is represented by equation (25). Similarly, R turn,r represented by equation (26). ( δ + β f l − β r l ) R t u r n , l = ( l f + l r ) ( δ + β f r − β r r ) R t u r n , r = ( l f + l r )

[0063] It can be assumed that R turn is sufficiently large compared to the wheelbase of the vehicle and that both β and δ are sufficiently small. R turn is represented by equation (27) using equations (25) and (26). In a process of deriving Equation (27), as represented by Equation (28), the product of the differences in β between the front and rear wheels is sufficiently small between the right and left wheels of the vehicle and can be regarded as zero. In addition, as represented by equation (29), f (β) obtained by subtracting the sum of β of the rear wheels from the sum of β of the front wheels of the vehicle compared to R turn sufficiently small and can be regarded as zero. Thus, "R turn " represented by Equation (20) (described previously). R t u r n = R t u r n , l + R t u r n , r 2 = l f + l r 2 ( 1 δ + β f l − β r l + 1 δ + β f r − β r r ) = l f + l r 2 ( ( 2 δ + f ( β ) ) δ 2 + δ ( f ( β ) ) + ( β f l − β r l ) ( β f r − β r r ) ) = l f + l r δ ( ( δ + f ( β ) 2 ) δ + f ( β ) ) ≈ l f + l r δ ( β f l − β r l ) ( β f r − β r r ) ≈ 0 f ( β ) = β f l + β f r − β r l − β r r ≈ 0

[0064] In the above description, “R turn " is expressed by the actual steering angle δ. However, it should be noted that "R turn " can also be conveniently expressed using a yaw rate instead of the actual steering angle δ. [Estimation of Ground Contact Load]

[0065] The longitudinal and lateral acceleration sensor 131 detects and outputs the longitudinal acceleration and the lateral acceleration of the vehicle. The (steering angle / yaw rate sensor) 132 detects and outputs a steering angle or a yaw rate of the vehicle. The wheel speed sensor 133 detects and outputs a wheel speed of the wheels of the vehicle. In addition, the network (described previously) outputs various physical quantities related to the vehicle. That is, the detecting section (described above) detects and outputs the physical quantity related to the vehicle.

[0066] The reference inertial load calculation section 111 calculates the reference inertial load dF est (k) using the physical quantity detected by the detection section.

[0067] The correction value calculation section 112 calculates the inertia load correction value dF z0,corr using the physical quantity detected by the detection section. More specifically, the correction value calculation section 112 calculates the inertia load correction value for correcting the influence of p-point during cornering according to Equation (15) (described earlier).

[0068] The inertia load estimating section 110 obtains an estimated value of an inertia load dF z0,iner tia by adding the inertial load correction value calculated by the correction value calculation section 112 to a reference inertial load calculated by the reference inertial load calculation section 111 . More specifically, the inertial load estimating section 110 obtains the estimated value of the inertial load according to Equation (14) (described earlier).

[0069] The inertial load estimating section 110 transmits the inertial load dF Z0,inertia to the deceleration section 142. The deceleration section 142 outputs the inertia load as necessary by decelerating the inertia load so that the inertia load is output at an appropriate timing according to subsequent control. For example, the deceleration section 142 decelerates the inertia load so that the inertia load is synchronized with a deceleration in a moving average process, this deceleration occurring in the road surface load estimating section 120 (described later). The adding section 143 combines the inertial load with a stable load F Z0nom transmitted from the stable load providing section 141 . The sum of the stable load and the inertial load is sent to the road surface load estimation section 120 and the adding section 144 .

[0070] In addition, the road surface load estimating section 120 outputs an estimated value of the road surface load. The road surface load estimating section 120 may output the estimated value of the road surface load with reference to the sum of the stable load and the inertial load. In this case, the estimated value of the road surface load is obtained in relation to the stable load and the inertial load.

[0071] The estimated value of the road surface load sent from the road surface load estimating section 120 is combined with the above-mentioned sum by the adding section 144 . In this case, the sum of the stable load, the inertial load and the road surface load is used as an estimated value F z0 of the ground contact load of the vehicle. [Effects]

[0072] In Embodiment 1, the physical quantity that can be detected by the universal sensor is used for calculating the reference inertial load and calculating the inertial correction value. This allows the sensor-related costs to be reduced. A comparison between (a) an actual measured value of the ground contact load obtained using an on-vehicle sensor for more directly detecting the ground contact load and (b) an estimated value of the ground contact load obtained according to Embodiment 1 shows that Embodiment 1 enables the estimated value of the ground contact load F z0 that is so accurate that it essentially agrees with the measured actual value.

[0073] In Embodiment 1, it is possible to use a solution of an equation of motion, which solution is obtained by applying the minimum norm solution. Therefore, Embodiment 1 configured in this way is more effective in estimating the ground contact load with high accuracy and is also more effective in making a correction that enables such estimation to be applied to a wide range of vehicle running conditions.

[0074] In Embodiment 1, the road surface load is estimated with reference to the stable load and the estimated inertial load. Therefore, Embodiment 1 configured in this way enables estimating the road surface load with higher accuracy compared to a case where the road surface load is estimated without reference to the stable load and the estimated inertial load. [Embodiment 2: Second embodiment of ground contact load estimation apparatus].

[0075] Another embodiment of the present invention is described below. Note that, for the sake of simplicity, elements whose functions are identical to those of the respective elements described in Embodiment 1 are given identical reference numerals, respectively, and the description of these elements is omitted. (Correction of the influence of a z , p-point and q-point)

[0076] In Embodiment 2, an inertia load correction value dF Z0,corr can be represented by equation (30) below. The first term in large brackets (the product of K a and a vector a) on the right side of equation (30) corrects an error of a z , p-point and q-point, which is caused by a minimum norm solution. In Equation (30), the vector a is represented by Equation (31) below, and a vector p is represented by Equation (16) (described earlier). d F z 0, c o r r → = ∑ F y 0 ( K a a → + K p ( h 0 t r r 2 ( t r f 2 + t r r 2 ) ) ( 1 + l 1 l x ) p ˙ ) a → = [ 1 − 1 − t r f t r r t r f t r r ] T

[0077] In Equation (30), K a an adjustment parameter. K a can be determined by: comparing an estimated value obtained by equation (30) with an actual measured value, and adjusting K appropriately a such that the estimated value is substantially identical to the actual measured value in estimating a ground contact load of a vehicle. [Estimation of Ground Contact Load]

[0078] A longitudinal and lateral acceleration sensor 131 detects and outputs the longitudinal acceleration and the lateral acceleration of the vehicle. A (steering angle / yaw rate sensor) 132 detects and outputs a steering angle or a yaw rate of the vehicle. A wheel speed sensor 133 detects and outputs a wheel speed of the wheels of the vehicle. In addition, a network (described above) outputs various physical quantities related to the vehicle. A detection section (described above) thus outputs a physical quantity related to the vehicle.

[0079] A reference inertial load calculation section 111 calculates a reference inertial load dF est (k) using the physical quantity detected by the detection section. More specifically, according to equation (13) (described above), the reference inertial load calculation section 111 calculates the reference inertial load as a solution to which the minimum norm solution is applied. For example, a system matrix section 301 transmits to an adding section 303 the product of a matrix A (described above) and a previously calculated value of a ground contact load dF est (k-1) , and an input matrix section 302 transmits to the adding section 303 the product of a matrix U (described above) and a matrix B. The adding section 303 combines these products to calculate the reference inertial load. The reference inertial load is sent from the reference inertial load calculation section 111 . A delay section 304 (i) adjusts the timing so that the reference inertial load to be transmitted to the system matrix section 301 has a previously calculated value in the next calculation of the reference inertial load, and (ii) outputs the reference inertial load received by the delay section 304.

[0080] A correction value calculation section 112 calculates the inertia load correction value dF Z0,corr using the physical quantity detected by the detection section. More specifically, according to equation (30), the correction value calculation section 112 calculates the inertia load correction value which includes an influence of p - point, a z and q - point corrected.

[0081] An inertia load estimating section 110 obtains an estimated value of an inertia load dF Z0,inertia by adding the inertial load correction value calculated by the correction value calculation section 112 to a reference inertial load calculated by the reference inertial load calculation section 111 . More specifically, the inertial load estimating section 110 obtains the estimated value of the inertial load according to Equation (14) (described earlier).

[0082] An inertial load estimating section 110 transmits the inertial load dF Z0,inertia to the deceleration section 142. The deceleration section 142 outputs the inertia load as necessary by decelerating the inertia load so that the inertia load is output at an appropriate timing according to subsequent control. For example, the deceleration section 142 decelerates the inertia load so that the inertia load is synchronized with a deceleration in a moving average process, this deceleration occurring in a road surface load estimating section 120 (described later). An adding section 143 combines the inertial load with a stable load F Z0nom transmitted from a stable load providing section 141 . The sum of the stable load and the inertial load is sent to the road surface load estimating section 120 and an adding section 144 .

[0083] In addition, the road surface load estimating section 120 outputs an estimated value of the road surface load. The road surface load estimating section 120 may output the estimated value of the road surface load with reference to the sum of the stable load and the inertial load. In this case, the estimated value of the road surface load is obtained in relation to the stable load and the inertial load.

[0084] The estimated value of the road surface load sent from the road surface load estimating section 120 is combined with the above-mentioned sum by the adding section 144 . In this case, the sum of the stable load, the inertial load and the road surface load is used as an estimated value F z0 of the ground contact load of the vehicle.

[0085] According to Embodiment 2, the road surface load is estimated as described below. In the following description, a functional configuration and a logic for estimating the road surface load in Embodiment 2 will be discussed. [Functional Configuration of Road Surface Load Estimation Section]

[0086] figure 8 is a block diagram illustrating an example of a functional configuration of a road surface load estimating section of Embodiment 2. FIG. According to Embodiment 2, the road surface load estimation section 120 has an effective tire radius variation calculation section 121, a first-gain calculation section 122, and a second-gain correction section 123 (see figure 8th). [Logic of Road Surface Load Estimation]

[0087] A non-linear tire characteristic of the wheels of the vehicle is linearly approximated and is represented by equations (51) and (52) below. In Equation (52), “F z0 " is the sum of the stable load and the inertial load as represented by equation (53). d F z 0, r o a d = − a 1 d R e a 1 = a 11 F z 0 + a 12 F z 0 = F z 0 n o m + d F z 0, i n e r t i a

[0088] In the above equations, a 1 constitute a first reinforcement, a 11 represents a first parameter, and a 12 represents a second parameter.

[0089] The first reinforcement a 1 indicates the stiffness of a wheel of the vehicle. The first reinforcement a 1 is represented by a spring constant in a relationship between the spring constant and the ground contact load of a tire. The relationship is represented by a non-linear curve, but can be approximated to a linear expression as represented by equation (52).

[0090] The first parameter a 11 and the second parameter a 12 are both adjustment parameters for applying the first gain a 1 to a wide range of conditions. The first parameter is represented by a slope of the linear expression obtained by the approximation described above, and the second parameter is represented by an intercept of the linear expression.

[0091] figure 9 is a view for describing a physical quantity related to a wheel of a vehicle. In figure 9 represents R e represents an effective radius of the tire, ω represents an angular velocity of the wheel, and uo represents a wheel center velocity parallel to a road surface. Considering a slip ratio of the tire, the effective radius R e represented by equation (54) below. Equation (55) is derived from a total differential of Equation (54). R e = u 0 ω ( 1 + s ) d R e R e = d u 0 u 0 + d s 1 + s − d ω ω

[0092] Let's assume that the slip ratio does not change. In this case, equation (56) is derived from equation (55), and further equation (57) is derived. In Equation (57), a 2 represents a second reinforcement. The second reinforcement a 2 is a parameter for adjusting the influence of a variation in wheel angular velocity on an estimation result. For example, the second gain may be determined by (i) comparing an actual measured value and an estimated value of the ground contact load of the vehicle running under a condition where the wheel angular velocity changes, and (ii) appropriately setting the second gain so that the estimated value is essentially equally effective under different driving conditions. d R e R e = d u 0 u 0 − d ω ω = d ω ω [ d u 0 × ω u 0 × d ω − 1 ] = d ω ω [ d u 0 R e × d ω ( 1 + s ) − 1 ] = d ω ω × a 2 d R e = a 2 R e ( d ω ω )

[0093] dω / ω in parentheses in Equation (57) can be approximated as shown by Equation (58). In Equation (58), "movavg(ω)" represents a moving average of wheel angular velocity. Thus, Equation (59) is derived from Equation (57). d ω ω ≈ ω − m o v a v g ( ω ) m o v a v g ( ω ) d R e = a 2 R e ( ω − m o v a v g ( ω ) m o v a v g ( ω ) )

[0094] Equation (60) is derived by substituting Equation (59) into Equation (51). The road surface load is calculated from equation (60). Equation (60) contains movavg(ω). d F z 0, r o a d = − a 1 × a 2 × R e ( ω − m o v a v g ( ω ) m o v a v g ( ω ) )

[0095] The second reinforcement a 2 can be represented by equation (61) below. In Equation (61), a 21 represents a third parameter. The third parameter a 21 is an adjustment parameter similar to the second gain. In equation (61) the third parameter leads to the same result as the second gain. a 2 = a 21

[0096] The second gain can be expressed using not only the third parameter but also another correction value for correcting an influence of a specific vehicle condition on the tire. For example, the second gain can be represented by equation (62). a 2 = a 21 × F s × F j e r k

[0097] In Equation (62), F s represents a correction value for correcting an influence of the slip ratio, and F jerk represents a correction value for correcting an error caused by a jerk. In this case, the third parameter is an adjustment parameter for reducing the influence of a correction made using these correction values ​​while the vehicle is running under a condition different from a Driving condition differs, which is to be corrected using the correction values. f s and F jerk may each (i) calculate a calculated value of a slip ratio related value, the calculated value being calculated by the second-gain correcting section (described later), or (ii) increase a detected value of the jerk detected by the detecting section and decrease or may substantially clear the calculated value or the sensed value according to a predetermined threshold. In order to make such a correction, it is possible to calculate the road surface load from equation (63). d F z 0, r o a d = − a 1 × a 2 × F s × F j e r k × R e ( ω − m o v a v g ( ω ) m o v a v g ( ω ) ) [Road surface load estimation]

[0098] The first gain calculation section 122 of the road surface load estimation section 120 calculates the first gain a 1 using at least the stable load and the inertial load. The first reinforcement a 1 is represented by the rigidity (a spring constant) of a wheel (tire) of the vehicle as described above, and can be represented by a linear expression that is close to a non-linear curve of the spring constant with respect to the ground contact load. Here the ground contact load is the sum of the stable load and the inertial load as previously described. The first gain calculation section 122 substitutes the above sum in Equation (52) so that the first gain is calculated.

[0099] The second-gain correcting section 123 also detects the jerk of the vehicle from the detecting section. More specifically, the second gain correction section 123 detects the jerk of the vehicle via a network such as a CAN.

[0100] The second gain correction section 123 also calculates the slip ratio related value of the vehicle from a value of the wheel speed sensor. More specifically, the second gain correcting section 123 acquires a numerical value representing F s in equation (62).

[0101] Moreover, the second gain correcting section 123 corrects the second gain according to at least the slip ratio related value and the jerk. It is assumed that the second gain is set as the adjustment parameter as previously described. More specifically, the second gain correction section 123 (i) determines F according to equation (62). s and F jerk , which reduce an influence of slip ratio and jerk, and (ii) uses F s and F jerk to correct the second gain according to equation (62).

[0102] In a case where it is considered that a change in the slip ratio related value has a large influence on the estimation result, it is possible to use F s set to adjust for such an influence. For example, F is s a coefficient by which the slip ratio related value is multiplied. In a case where the slip ratio related value is smaller than a predetermined value, F s be 0 In a case where the slip ratio related value is not smaller than the predetermined value, F s 1 so that the slip ratio related value is adopted.

[0103] In a case where a change in jerk motion is assumed to have a large impact on the estimation result, it is possible to use F jerk set to adjust for such an influence. For example, F is jerk a coefficient by which the detected jerk is multiplied. In a case where the jerk is greater than a predetermined value, F s be 0 In a case where the jerk is not greater than the specified value, F jerk 1 so that the detected jerk movement is accepted.

[0104] As represented by equation (62), the second gain correcting section 123 calculates the second gain obtained by multiplying F s and F jerk was corrected with the third parameter. The third parameter a 21 in equation (61) and the third parameter a 21 in Equation (62) may be identical to or different from each other.

[0105] The tire effective radius variation calculation section 121 calculates the variation of an effective tire radius by multiplying a variation of a wheel angular velocity by the second gain. The variation of a wheel angular velocity is a numerical value including a variation value dω of the wheel angular velocity ω. More specifically, the effective tire radius variation calculation section 121 calculates the variation of an effective tire radius by multiplying the terms (except a 1 ) on the right-hand side of equation (60).

[0106] The road surface load estimation section 120 estimates the road surface load by multiplying the variation of an effective tire radius calculated by the effective tire radius variation calculation section 121 by the first gain. More specifically, the road surface load estimating section 120 obtains an estimated value of the road surface load according to equation (60) by multiplying the variation of an effective tire radius by the first gain.

[0107] The ground contact load estimating device 100 obtains an estimated value of the ground contact load F z0 of the vehicle by adding (i) the stable load, (ii) the inertial load estimated by the inertial load estimating section 110, and (iii) the road surface load estimated by the road surface load estimating section 120 to each other. [Effects]

[0108] Embodiment 2 further realizes the following effects in addition to the effects of Embodiment 1 described above. According to Embodiment 2, it is possible to (i) estimate the road surface load of the vehicle with higher accuracy. Furthermore, by including such an estimated value of the road surface load, it is possible to estimate the ground contact load of the vehicle with much higher accuracy. Furthermore, by correcting the second gain according to a change in acceleration / deceleration of the wheel, it is possible to estimate the road surface load with much higher accuracy. [Embodiment 3: embodiment of a suspension control device].

[0109] In the following description, an example in which a physical quantity estimation device according to Embodiment 3 is applied to a control device for controlling a suspension of a vehicle will be discussed. It should be noted that for the sake of simplicity, elements whose functions are identical to those of the respective elements described in Embodiments 1 and 2 are given identical reference numerals respectively, and the description of these elements is omitted.

[0110] A control device according to Embodiment 3 (i) estimates a ground contact load acting on the vehicle having the suspension, and (ii) controls a damping force of the suspension according to the ground contact load. The control device of Embodiment 3 can be configured as in the case of a publicly known control device of a suspension, except that the control device of Embodiment 3 includes a ground contact load estimation device (described above) and the damping force of the suspension according to that estimated by the ground contact load estimation device ground contact load controls.

[0111] figure 10 is a view schematically illustrating an example of a configuration of a vehicle having the ground contact load estimation device described above. As in figure 10 illustrates, a vehicle 900 includes a suspension 150, a vehicle body 200, wheels 300, a vehicle speed sensor 450 that detects a vehicle speed (V), an engine 500, and an electronic control unit (Electronic Control Unit, ECU) 600. The ECU 600 corresponds to a processor (described above) and includes the ground contact load estimating device (described above).

[0112] It should be noted that the letters A to E in the reference numbers each represent a position in the vehicle 900 . A represents a left front position in vehicle 900, B represents a right front position in vehicle 900, C represents a left rear position in vehicle 900, D represents a right rear position in vehicle 900, and E represents a rear position in the vehicle 900.

[0113] In addition, the vehicle 900 has various sensors, such as a longitudinal acceleration sensor 340 that detects the acceleration in the longitudinal direction of the vehicle 900 . Such a sensor corresponds to a universal sensor (described above). The vehicle 900 has a storage medium. The storage medium stores various information necessary for estimating a physical quantity. Examples of such information are various physical quantities related to the vehicle, such as a wheel radius and a mass (vehicle weight) of the vehicle.

[0114] Respective output values ​​of the various sensors are input to the ECU 600 via a controller area network (CAN) 370, and control signals are transmitted from the ECU 600 to respective sections. It is possible to resupply the sensors to estimate the physical quantity (which will be described later). However, from a cost perspective, the sensors are preferably sensors that are already present in the vehicle 900 .

[0115] According to Embodiment 3, the damping force of the suspension is controlled according to an estimated value of the ground contact load of the vehicle, the estimated value being as accurate as an actual measured value of the ground contact load of the vehicle. This makes it possible to sufficiently improve the running stability of the vehicle without using a special sensor different from the universal sensor.

[0116] In Embodiment 3, the ground contact load estimated in the controller is directly used to control the damping force of the suspension of the vehicle. According to an aspect of the present invention, the ground contact load thus estimated can be used to control various devices of the vehicle, as in the case of the suspension. Examples of such devices include not only an ordinary suspension but also an electronically controlled suspension, a steering device, and an electronically controlled driving force transmission device. The estimated ground contact load can be used to control one or more of these devices of the vehicle. In the control of these devices, an estimation result of the ground contact load can be used directly as in Embodiment 3 or indirectly to control these devices. Indirect use of the ground contact load estimation result includes, for example, converting the estimation result into another state quantity to use an estimated value of the state quantity obtained through the conversion for controlling the one or more other devices. By using the estimated value of the ground contact load (described above) to control the one or more other devices, as in the case of Embodiment 3, it is possible to sufficiently or more improve the running stability of the vehicle without using a special sensor , which differs from the universal sensor. [Example of a software implementation]

[0117] Control blocks of the ground contact load estimation device 100 (particularly, the inertial load estimation section 110 and the road surface load estimation section 120) can be realized by a logic circuit (hardware) arranged in an integrated circuit (IC chip) or the like, or alternatively can be realized by software will be realized.

[0118] In the latter case, the ground contact load estimating device 100 includes a computer that executes instructions of a program, which is software that realizes the functions described above. For example, the computer not only includes at least one processor, but also includes a computer-readable storage medium on which the program is stored. An object of the present invention can be achieved by the processor reading the program stored in the storage medium and executing it in the computer. Examples of the processor include a central processing unit (CPU).

[0119] Examples of the storage medium include "a non-transitory tangible medium", such as not only a read-only memory (ROM) but also a tape, a disk, a card, a semiconductor memory and a programmable logic circuit. The computer may also include random access memory (RAM) or the like into which the program is loaded.

[0120] The program can be made available to the computer via any transmission medium (such as a communication network or a broadcast wave) that allows the transmission of the program. It should be noted that an aspect of the present invention may also be embodied in the form of a computer data signal in which the program is embodied via electronic transmission and embedded in a carrier wave.

[0121] The present invention is not limited to the embodiments but can be modified by a person skilled in the art within the scope of the claims. The present invention also includes within its technical scope any embodiments realized by combining technical means disclosed in different embodiments. [Variant]

[0122] In one aspect of the present invention, a ground contact load can be obtained, for example, by a method disclosed in paragraph

[0151] of Japanese Patent Application Tokukai Publication No. 2008-074184.

[0123] In Embodiment 1 (described above), the elements other than the inertial load estimation section 110 may be omitted as appropriate according to the accuracy with which the ground contact load is to be estimated. For example, it is possible to omit the road surface load estimating section 120 and the adding section 144 in Embodiment 1. In this case, the sum of the stable load and the inertial load is the estimated value of the ground contact load.

[0124] In Embodiment 2 (described above), part of the elements may be omitted as necessary according to the accuracy with which the ground contact load is to be estimated. For example, in Embodiment 2, it is possible to omit the second gain calculation section in a case where the second gain is not corrected.

[0125] Alternatively, it is possible to omit or integrate part of the calculation processes as needed to achieve a simpler calculation process, for example. For example, in Embodiment 2, the road surface load can be calculated by (i) finding a value obtained by multiplying the first gain a 1 and the second reinforcement a 2 is obtained, and (ii) a resulting gain value is applied to, for example, equation (60) (described previously). Aspects of the present invention can also be expressed as follows:

[0126] As is apparent from the above description, a ground contact load estimating device (100) of an embodiment of the present invention is a ground contact load estimating device for estimating a ground contact load of a vehicle (900), the ground contact load estimating device including: a detecting section configured to acquire physical quantity related to the vehicle; and an inertial load estimating section (110) including: (i) a reference inertial load calculating section (111) configured to calculate a reference inertial load using the physical quantity detected by the detecting section, and (ii) a correction value calculating section (112) configured to calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load.

[0127] This configuration not only makes it possible to reduce sensor-related costs, but also makes it possible to estimate a ground contact load of a vehicle with sufficiently high accuracy.

[0128] According to an embodiment of the present invention, the detection section can detect as the physical quantity: a value of a longitudinal acceleration sensor (131) that detects the longitudinal acceleration of the vehicle, a value of a lateral acceleration sensor (131) that detects the lateral acceleration of the vehicle, a value of a wheel speed sensor ( 133) that detects a wheel angular velocity of the vehicle, a value of a cornering information sensor that detects cornering information of the vehicle, a mass of the vehicle, a center of mass height of the vehicle, a roll moment of inertia, a pitching moment of inertia, a front-axle inter-center of gravity distance of the vehicle, a rear-axle inter-center of gravity distance of the vehicle , a front tread length of the vehicle, and a rear tread length of the vehicle. In addition, the reference inertial load calculation section can calculate the reference inertial load according to a model of the vehicle using the value of the longitudinal acceleration sensor, the value of the lateral acceleration sensor, the mass of the vehicle, the center of mass height of the vehicle, the rolling moment of inertia, the pitching moment of inertia, the front axle inter-center of gravity distance of the vehicle, the Calculate the vehicle's rear center of gravity distance, the front tread length, and the rear tread length. In addition, the correction value calculation section may calculate the inertial load correction value using the mass of the vehicle, the center of mass height of the vehicle, the wheel speed sensor value, the cornering information sensor value, the rolling moment of inertia, the front tread length, and the rear tread length.

[0129] The configuration makes it possible to detect the physical quantity using a universal sensor or to estimate the ground contact load with sufficiently high accuracy according to the physical quantity specific to the vehicle.

[0130] According to an embodiment of the present invention, the model may be a solution of an equation of motion represented by a linear system, the solution being obtained by applying a minimum norm solution.

[0131] The configuration makes it possible to obtain an estimated value of the ground contact load according to an appropriate equation of motion and using a solution to which an appropriate correction has been made. The configuration is therefore more effective to obtain an estimated value of the ground contact load with high accuracy, which is applied to a wide range of vehicle running conditions.

[0132] According to an embodiment of the present invention, the cornering information sensor may be a yaw rate sensor or a steering angle sensor (132).

[0133] The configuration is more effective to estimate the ground contact load of the vehicle with high accuracy using the physical quantity detected using a universal sensor.

[0134] According to an embodiment of the present invention, the detection section may include (i) a wheel speed sensor that detects the wheel angular speed of the vehicle, and (ii) detect the physical quantity that includes the wheel angular speed, a stable load of the vehicle, and an inertial load of the vehicle, and the ground contact load estimating device may further include a road surface load estimating section (120) configured to estimate a road surface load of the vehicle. The road surface load estimation section may include: a first-gain calculation section (122) configured to use at least the stable load of the vehicle and the inertial load of the vehicle to calculate a first gain having at least the rigidity of a wheel ( 300) of the vehicle; and an effective tire radius variation calculation section (121) configured to calculate a variation of an effective tire radius by multiplying a variation of a wheel angular velocity by a second gain to reduce an influence of the variation of a wheel angular velocity on an estimation result , and the road surface load estimating section may estimate the road surface load by multiplying the variation of an effective tire radius by the first gain. The ground contact load estimating device may estimate the ground contact load of the vehicle by: adding together (i) the inertial load estimated by the inertial load estimating section and (ii) the road surface load estimated by the road surface load estimating section.

[0135] The configuration makes it possible to detect the physical quantity using a universal sensor or to estimate the road surface load of the vehicle according to the physical quantity specific to the vehicle with sufficiently high accuracy and also to estimate the ground contact load containing such road surface load and has higher accuracy.

[0136] According to an embodiment of the present invention, the detecting section may further detect a jerk of the vehicle, and the road surface ground contact load estimating section may further include a second-gain correcting section (123) configured to correct the second gain. The second gain correcting section may calculate a slip ratio related value of the vehicle from the wheel speed sensor value to correct the second gain according to at least the slip ratio related value and the jerk.

[0137] The configuration is more effective to estimate the road surface load with higher accuracy.

[0138] A control device of an embodiment of the present invention is a control device (ECU 600) for estimating a ground contact load acting on a vehicle and using the ground contact load directly or indirectly to control one or more other devices of the vehicle. The control device includes: a detection section configured to detect a physical quantity related to the vehicle; and an inertial load estimating section including: (i) a reference inertial load calculating section configured to calculate a reference inertial load using the physical quantity detected by the detecting section, and (ii) a correction value calculating section configured to calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load.

[0139] The configuration not only makes it possible to reduce the sensor-related costs, but also makes it possible to control the one or more other devices that control a running state of the vehicle according to the ground contact load estimated with sufficiently high accuracy. This makes it possible to sufficiently improve the running stability of the vehicle.

[0140] In accordance with an embodiment of the present invention, the one or more other devices may be one or more devices selected from the group consisting of an electronically controlled suspension, a steering device, and an electronically controlled powertrain.

[0141] The configuration is more effective to improve the driving stability of the vehicle.

[0142] A ground contact load estimating method of an embodiment of the present invention is a ground contact load estimating method for estimating a ground contact load of a vehicle, the ground contact load estimating method including the steps of: acquiring a physical quantity related to the vehicle; calculating a reference inertial load using the detected physical quantity; calculating an inertial load correction value using the detected physical quantity; and estimating an inertia load by adding the inertia load correction value to the reference inertia load.

[0143] This configuration not only makes it possible to reduce sensor-related costs, but also makes it possible to estimate a ground contact load of a vehicle with sufficiently high accuracy. reference list 100 Ground Contact Load Estimator 110 inertial load estimating section 111 reference inertial load estimating section 112 correction value calculation section 120 road surface load estimating section 121 Effective Tire Radius Variation Calculation Section 122 First Gain Calculation Section 123 Second Gain Calculation Section 131 lateral acceleration sensor 132 steering angle / yaw rate sensor 133 wheel speed sensor 141 stable load provision section 142, 304 delay section 143, 144, 303 adder section 200 vehicle body 300 wheel 301 system matrix section 302 input matrix section 340 longitudinal acceleration sensor 450 vehicle speed sensor 500 engine 600 ECUs 900 vehicle Original Claims A ground contact load estimating device for estimating a ground contact load of a vehicle, the ground contact load estimating device comprising: - a detection section configured to detect a physical quantity related to the vehicle; and - an inertial load estimation section comprising: (i) a reference inertial load calculation section configured to calculate a reference inertial load using the physical quantity detected by the detection section, and (ii) a correction value calculation section configured to calculate a calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load. 2. Ground contact load estimating device according to claim 1, wherein - the detecting section, as the physical quantity, a value of a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, a value of a lateral acceleration sensor that detects the lateral acceleration of the vehicle, a value of a wheel speed sensor that detects a wheel angular velocity of the vehicle, a value of a turning information sensor, the turning information of the vehicle, detecting a mass of the vehicle, a center of mass height of the vehicle, a roll moment of inertia, a pitching moment of inertia, a front axle inter-centre of gravity distance of the vehicle, a rear axle inter-centre of gravity distance of the vehicle, a front tread length of the vehicle and a rear tread length of the vehicle, - the reference inertial load calculation section calculates the reference inertial load according to a model of the vehicle using the value of the longitudinal acceleration sensor, the value of the lateral acceleration sensor, the mass of the vehicle, the center of mass height of the vehicle, the rolling moment of inertia, the pitching moment of inertia, the front axle inter-centricular center distance of the vehicle, the rear axle calculates the vehicle's center of gravity distance, the front tread length, and the rear tread length, and - the correction value calculation section calculates the inertial load correction value using the mass of the vehicle, the center of mass height of the vehicle, the wheel speed sensor value, the cornering information sensor value, the rolling moment of inertia, the front tread length and the rear tread length. 3. The ground contact load estimation device according to claim 2, wherein the model is a model of a solution of an equation of motion represented by a linear system, the solution being obtained by applying a minimum norm solution. 4. The ground contact load estimation device according to claim 2 or 3, wherein the cornering information sensor is a yaw rate sensor or a steering angle sensor. 5. ground contact load estimation device according to any one of claims 1 to 4, wherein - the detecting section (i) includes a wheel speed sensor that detects the wheel angular speed of the vehicle, and (ii) detects the physical quantity including the wheel angular speed, a stable load of the vehicle, and an inertial load of the vehicle, - the ground contact load estimating device further comprises a road surface load estimating section configured to estimate a road surface load of the vehicle, - the road surface load estimation section includes: - a first gain calculation section configured to use at least the stable load of the vehicle and the inertial load of the vehicle to calculate a first gain indicative of at least rigidity of a wheel of the vehicle; and - an effective tire radius variation calculation section configured to calculate a variation of an effective tire radius by multiplying a variation of a wheel angular velocity by a second gain in order to reduce an influence of the variation of a wheel angular velocity on an estimation result, - the road surface load estimating section estimates the road surface load by multiplying the variation of an effective tire radius by the first gain, and - the ground contact load estimating device estimates the ground contact load of the vehicle by adding together (i) the inertial load estimated by the inertial load estimating section and (ii) the road surface load estimated by the road surface load estimating section. 6. ground contact load estimation apparatus according to claim 5, wherein - the detecting section further detects the jerk of the vehicle, - the road surface load estimation section further comprises a second gain correction section configured to correct the second gain, and - the second gain correction section uses the value of the wheel speed sensor to calculate a slip ratio related value of the vehicle to correct the second gain according to at least the slip ratio related value and the jerk. 7. A controller for estimating a ground contact load acting on a vehicle and for using the ground contact load directly or indirectly to control one or more other devices of the vehicle, the controller comprising: - a detection section configured to detect a physical quantity related to the vehicle; and - an inertial load estimation section comprising: (i) a reference inertial load calculation section configured to calculate a reference inertial load using the physical quantity detected by the detection section, and (ii) a correction value calculation section configured to calculate a calculate an inertial load correction value using the physical quantity detected by the detecting section, wherein the inertial load estimating section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load. 8. The control device of claim 7, wherein the one or more other devices is one or more devices selected from the group consisting of an electronically controlled suspension, a steering device, and an electronically controlled drive force transfer device. 9. A ground contact load estimation method for estimating a ground contact load of a vehicle, the ground contact load estimation method comprising the following steps: - detecting a physical quantity related to the vehicle; - calculating a reference inertial load using the detected physical quantity; - calculating an inertial load correction value using the detected physical quantity; and - Estimate an inertia load by adding the inertia load correction value to the reference inertia load.

Claims

[1] Ground contact load estimating device for estimating a ground contact load of a vehicle, the ground contact load estimating device comprising: - a sensing section configured to detect, as a physical quantity relating to the vehicle, a longitudinal acceleration sensor value that detects the longitudinal acceleration of the vehicle, a lateral acceleration sensor value that detects the lateral acceleration of the vehicle, a wheel speed sensor value that detects a wheel angular velocity of the vehicle, a cornering information sensor value that detects cornering information of the vehicle, a mass of the vehicle, a center of mass height of the vehicle, a rolling moment of inertia, a pitching moment of inertia, a front axle center of gravity distance of the vehicle, a rear axle center of gravity distance of the vehicle, a front tread length of the vehicle, and a rear tread length of the vehicle; and - an inertial load estimation section comprising: (i) a reference inertial load calculation section configured to calculate a reference inertial load according to a model of the vehicle using the longitudinal acceleration sensor value, the lateral acceleration sensor value, the wheel speed sensor value, the vehicle mass, the vehicle center of mass height, the rolling moment of inertia, the pitching moment of inertia, the vehicle's front axle intermediate center of mass distance, the vehicle's rear axle intermediate center of mass distance, the front tread length, and the rear tread length, each as acquired by the acquisition section; and (ii) a correction value calculation section configured to calculate an inertial load correction value using the vehicle mass, the vehicle's center of mass height, the wheel speed sensor value, and the cornering information sensor value.to calculate the rolling moment of inertia, the front tread length and the rear tread length, each acquired by the acquisition section, wherein the inertial load estimation section is configured to estimate an inertial load by adding the inertial load correction value to the reference inertial load, where the inertial load means a variation in the ground contact load due to the effect of the vehicle cornering and the effect of the vehicle accelerating / decelerating. [2] Ground contact load estimating device according to claim 1, wherein the model is a model of a solution of an equation of motion represented by a linear system, wherein the solution is obtained by applying a minimum norm solution. [3] Ground contact load estimating device according to claim 1 or 2, wherein the cornering information sensor is a yaw rate sensor or a steering angle sensor. [4] Ground contact load estimating device according to one of claims 1 to 3, wherein - the detection section (i) comprises a wheel speed sensor that detects the wheel angular velocity of the vehicle, and (ii) detects the physical quantity that comprises the wheel angular velocity, a stable load of the vehicle and an inertial load of the vehicle, - the ground contact load estimation device further includes a road surface load estimation section configured to estimate a road surface load of the vehicle, - the road surface load estimation section includes the following: - a first reinforcement calculation section configured to use at least the vehicle's stable load and inertial load to calculate a first reinforcement that specifies at least the stiffness of one wheel of the vehicle; and - an effective tire radius variation calculation section configured to calculate a variation of an effective tire radius by multiplying a variation of a wheel angular velocity with a second gain to reduce the influence of the variation of a wheel angular velocity on an estimation result, - the road surface load estimation section estimates the road surface load by multiplying the variation of an effective tire radius by the first reinforcement, and - the ground contact load estimator estimates the ground contact load of the vehicle by adding (i) the inertial load estimated by the inertial load estimator section and (ii) the road surface load estimated by the road surface load estimator section. [5] Ground contact load estimating device according to claim 4, wherein - the detection section also detects the jerking movement of the vehicle, - the road surface load estimation section also includes a second reinforcement correction section configured to correct the second reinforcement, and - the second gain correction section uses the value from the wheel speed sensor to calculate a slip ratio-related value of the vehicle in order to correct the second gain according to at least the slip ratio-related value and the jerk movement. [6] Control device comprising a ground contact load estimating device according to any one of claims 1 to 5, wherein the control device directly or indirectly uses a ground contact load estimated by the contact load estimating device to control one or more other devices of the vehicle. [7] Control device according to claim 6, wherein one or more other devices are one or more devices selected from the group consisting of an electronically controlled suspension, a steering device and an electronically controlled drive power transmission device. [8] Ground contact load estimation method for estimating a ground contact load of a vehicle, wherein the ground contact load estimation method comprises the following steps: - Detect, as a physical quantity relating to the vehicle, a value from a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, a value from a lateral acceleration sensor that detects the lateral acceleration of the vehicle, a value from a wheel speed sensor that detects a wheel angular velocity of the vehicle, a value from a cornering information sensor that detects cornering information of the vehicle, a mass of the vehicle, a center of mass height of the vehicle, a rolling moment of inertia, a pitching moment of inertia, a front axle intermediate center of gravity distance of the vehicle, a rear axle intermediate center of gravity distance of the vehicle, a front tread length of the vehicle, and a rear tread length of the vehicle; - Calculating a reference inertial load according to a model of the vehicle using the longitudinal acceleration sensor value, the lateral acceleration sensor value, the wheel speed sensor value, the vehicle mass, the vehicle center of mass height, the rolling moment of inertia, the pitching moment of inertia, the vehicle's front axle intermediate center of gravity distance, the vehicle's rear axle intermediate center of gravity distance, the front tread length and the rear tread length, each of which were recorded; - Calculating an inertia correction value using the vehicle mass, the vehicle's center of gravity height, the wheel speed sensor value, the cornering information sensor value, the rolling moment of inertia, the front tread length, and the rear tread length, each as recorded; and - Estimating an inertial load by adding the inertial load correction value to the reference inertial load, where the inertial load means a variation in the ground contact load due to the effect of the vehicle cornering and the effect of the vehicle accelerating / decelerating.