Wheel alignment state detection method and apparatus, wheel alignment state compensation method and apparatus

Abstract

The present invention provides a method and apparatus capable of detecting and compensating for wheel alignment (alignment) conditions even while a vehicle is in motion. [Solution] When the alignment state of vehicle 1 is detected by the processor 5, the surface temperature of the tires 3 mounted on the wheels 2FR and 2FL whose alignment state should be detected is detected, and the alignment state is determined based on the comparison result of the surface temperatures of the tires 3 during turning. Furthermore, if the alignment state is determined to be in a state of large caster angle, the control amount of the straight-line stability improvement control in vehicle 1 is corrected to be smaller the larger the caster angle, and if it is determined to be in a state of large camber angle, the control amount of the steering response improvement control in vehicle 1 is corrected to be smaller the larger the camber angle.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for detecting wheel alignment status, and a method and apparatus for compensating for wheel alignment status. [Background technology]

[0002] Patent Document 1 below discloses a technique for monitoring the deformation of a tire using a sensor provided on the tread portion of the tire, and for estimating the dynamic state of the tire, such as the load state. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-343281 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the technology described in Patent Document 1 above only estimates the dynamic state of the tire, and there is currently no technology that detects the wheel alignment state while the vehicle is in motion, or that compensates for the wheel alignment state based on the detection results. The present invention aims to provide a technology that can detect and compensate for the wheel alignment (hereinafter simply referred to as alignment) state even while a vehicle is in motion. [Means for solving the problem]

[0005] One aspect of the present invention involves detecting the alignment state of a vehicle using a processing unit, by detecting the surface temperature of the tires mounted on the wheels whose alignment state is to be detected, and determining the alignment state based on the comparison of the surface temperatures of the tires during turning. Furthermore, another aspect of the present invention is characterized in that, if the alignment state determination determines that the caster angle is large, the control amount of the vehicle's straight-line stability improvement control is corrected to be smaller the larger the caster angle, and if the camber angle is large, the control amount of the vehicle's steering response improvement control is corrected to be smaller the larger the camber angle. [Effects of the Invention]

[0006] According to the present invention, it is possible to detect and compensate for the alignment state even while the vehicle is in motion. [Brief explanation of the drawing]

[0007] [Figure 1] This is a system configuration diagram of a vehicle equipped with an alignment detection and compensation system, which is one embodiment of the present invention. [Figure 2] This is an explanatory diagram of the change in vertical load on each wheel of the vehicle shown in Figure 1. [Figure 3] This is an explanatory diagram of the heat generation and heat dissipation in a wheel tire. [Figure 4] Figure 1 is a flowchart of the calculation process performed in the tire temperature estimation unit. [Figure 5] This is an explanatory diagram of the tire temperature dependence model. [Figure 6] Figure 1 is an explanatory diagram of the tire surface sensor. [Figure 7] This is an explanatory diagram of the alignment detected by the alignment state detection unit in Figure 1. [Figure 8] This is an explanatory diagram of tire surface temperature during cornering. [Figure 9] This is an explanatory diagram of alignment condition compensation control according to the caster angle. [Figure 10] Figure 1 is an explanatory diagram of the output gain used in the electric power steering system. [Figure 11] Figure 9 shows the control map when the alignment condition compensation control is implemented using an electric power steering system. [Figure 12]This is an explanatory diagram of alignment condition compensation control according to the camber angle. [Figure 13] This is the output gain control map when the alignment state compensation control shown in Figure 12 is implemented using the operation control device shown in Figure 1. [Figure 14] Figure 1 is a flowchart of the calculation process performed by the alignment state detection unit. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. The vehicle 1 of the embodiment shown in Figure 1 is an autonomous vehicle having four wheels 2i: front right wheel 2FR, front left wheel 2FL, rear right wheel 2RR, and rear left wheel 2RL. The vehicle 1 is also equipped with a driving control device 34 for autonomous driving the vehicle 1. The vehicle 1 is also equipped with a drive electric motor (not shown) as a drive source for the drive device that drives the vehicle 1, and the operating state of this drive electric motor is controlled by a drive controller (not shown). It is also possible to apply braking force to each wheel 2i by regenerating the drive electric motor, which is the drive source. Furthermore, this vehicle 1 is equipped with a hydraulic brake device as a braking device for braking the vehicle 1, and therefore each wheel 2i is provided with a hydraulic brake mechanism 14. This hydraulic brake mechanism 14 can also apply braking force to each wheel 2i by operating the brake pedal. However, in order to enable autonomous driving, the vehicle 1 is equipped with a hydraulic control unit 14a that increases, maintains, and decreases the hydraulic pressure in the hydraulic brake mechanism 14 of each wheel 2i. This hydraulic control unit 14a is composed of a pressurizing pump for increasing or decreasing the hydraulic pressure to the hydraulic brake mechanism 14, a switching valve for switching between the hydraulic pressure from the brake pedal and the hydraulic pressure from the pressurizing pump, and hydraulic control valves that can individually increase, maintain, and decrease the hydraulic pressure in the hydraulic brake mechanism 14 of each wheel 2i. The components of this hydraulic control unit 14a operate in accordance with control signals from the hydraulic controller 14b. The vehicle 1 is also equipped with a vehicle behavior control device 13 that controls the operating state of this hydraulic brake system and controls the vehicle's yaw moment (yawing motion). This vehicle behavior control device 13, similar to well-known yaw rate control devices, calculates the target yaw rate of the vehicle 1 in the target yaw rate calculation unit 13a based on, for example, the steering angle of the steering wheel and the vehicle's speed, and calculates the target braking force for each wheel 2i necessary to achieve this target yaw rate in the target braking force calculation unit 13b. The hydraulic controller 14b, which receives the target braking force set by the target braking force calculation unit 13b, operates the hydraulic control unit 14a to control the yaw rate (yawing motion) of the vehicle 1 so that the target braking force for each wheel 2i is achieved.To enhance yawing motion, for example, by applying braking force to the wheel on the inside of the turn, the vehicle 1 will turn (orbit), and as a result, the control to enhance yawing motion becomes a control to improve steering responsiveness. Therefore, this vehicle behavior control device 13 corresponds to a control means for improving the steering responsiveness of the vehicle 1.

[0009] Furthermore, in this embodiment, an electric power steering device 12 is provided as a steering device. This electric power steering device 12 uses an electric motor 15, which is an actuator, to operate a steering mechanism (not shown) to steer the two front wheels 2FR and 2FL, which are the steering wheels. The driving control device 34 controls the operating state of the electric motor 15 of this electric power steering device 12 to achieve automatic steering. This electric power steering device 12 can also be operated by the driver. The driver's steering torque is detected, and an assist torque calculation unit 12a sets an auxiliary torque, so-called assist torque, corresponding to this steering torque. Steering assistance is realized by controlling the operating state of the electric motor 15 with the motor controller 12b so that this assist torque is achieved. When steering assist control is performed by this electric power steering device 12, as will be described later and as is well known, the assist force for steering is reduced as the travel speed of the vehicle 1 increases. This control of reducing the steering assist force corresponds to the vehicle 1's straight-line stability improvement control means. Vehicle 1 is also equipped with an environmental recognition system for recognizing the surrounding environment, and a communication system for vehicle-to-infrastructure and vehicle-to-vehicle communication, as well as controllers for controlling each of these systems (none of which are shown). The driving control device 34 for autonomous driving of Vehicle 1, for example, based on control inputs such as surrounding environment information obtained from the environmental recognition system and communication information obtained from the communication system, it manages the control state of the controlled objects in the drive system, braking system, and steering system, and outputs control commands to the controllers of the drive system, braking system, and steering system based on the driving action plan used in current autonomous driving logic of Level 3 or higher. As shown in Figure 3, each wheel 2i is fitted with a tire (pneumatic tire) 3.

[0010] Furthermore, this vehicle 1 is equipped with a tire surface temperature management device 4 that supplies the surface temperature of the tires 3 of each wheel 2i to the aforementioned driving control device 34, and also detects the alignment state of the two front wheels 2FR and 2FL. This tire surface temperature management device 4 is configured as a functional unit comprising a tire surface temperature calculation unit 6 that calculates the surface temperature of each wheel 2i and an alignment state detection unit 7. The driving control device 34, for example, according to the tire temperature dependence model that represents the correlation between the surface temperature of the tire 3 and the maximum friction coefficient of the tire 3 shown in Figure 5, calculates the surface temperature T of the tires 3 of each wheel 2i by the tire surface temperature calculation unit 6. i The maximum friction coefficient μ of each wheel 2i TMAXi Obtain this maximum friction coefficient μ TMAXi Using this, control commands are calculated and set to each controller of the drive system, braking system, and steering system, for example. In order for this tire surface temperature management device 4 to function, the vehicle 1 is equipped with a steering angle sensor 21, an acceleration sensor 22, a speed sensor 23, a driving force sensor 24, a road surface temperature sensor 25, an outside air temperature sensor 26, and a TPMS (Tire Pressure Monitoring System) 27. The steering angle sensor 21 detects the steering angle (turning angle) δ of the front wheels 2FR and 2FL, which are the steering wheels of the vehicle 1. The acceleration sensor 22 detects the longitudinal acceleration a generated in the vehicle 1. X and the acceleration a in the width direction (lateral direction) of vehicle 1 Y The speed sensor 23 detects the vehicle's speed V. The drive force sensor 24 detects the drive force and braking force (braking force) F generated in the vehicle 1. XTTL It detects the road surface temperature T of the road surface on which the vehicle 1 is traveling. ROAD The sensor detects the temperature in [°C] and consists of a non-contact temperature sensor, for example, mounted on the underside of the vehicle body of vehicle 1, in which case it is positioned facing the road surface on which vehicle 1 travels. The outside air temperature sensor 26 detects the outside air temperature T outside vehicle 1. AIRIt detects [°C], and in this embodiment, it is attached to a portion facing the inside of the wheelhouse of the vehicle 1. That is, the outside air temperature sensor 26 in this embodiment detects the temperature around the tire 3 of the wheel 2i in the wheelhouse. The TPMS 27 detects the air pressure of the tire 3 of each wheel 2i and also detects the internal temperature (tire internal temperature) T of the tire 3 INR It detects [°C], and for example, it is attached to the wheel of each wheel 2i. The detection information detected by the steering angle sensor 21, the acceleration sensor 22, the speed sensor 23, and the driving force sensor 24 is acquired by the vehicle state acquisition unit 17 constructed in the processor 5, which will be described later, in the tire surface temperature calculation unit 6. Also, the road surface temperature T detected by the road surface temperature sensor 25 ROAD is similarly acquired by the road surface temperature acquisition unit 18 constructed in the processor 5, which will be described later. Also, the outside air temperature T detected by the outside air temperature sensor 26 AIR and the tire internal temperature T detected by the TPMS 27 INR are similarly acquired by the environmental temperature acquisition unit 19 constructed in the processor 5, which will be described later. Note that the tire internal temperature T INR is used with the subscript i indicating the position of each wheel 2i attached.

[0011] Vehicle 1 is also equipped with a front tire surface temperature sensor 28 that non-contactually detects the surface temperature of the front two tires 2FR and 2FL. Figure 6 is a plan view showing the positional relationship between the front two tires 2FR and 2FL and the front tire surface temperature sensor 28. As shown in Figure 6a, the front tire surface temperature sensor 28 is positioned on the front side of each of the front two tires 2FR and 2FL, and is positioned opposite the center of the tire tread in the width direction when Vehicle 1 is driving straight. With this front tire surface temperature sensor 8, not only when Vehicle 1 is driving straight, but also when it is making a slight right turn (slight right turn in the figure) as shown in Figure 6b and a slight left turn (slight left turn in the figure) as shown in Figure 6c, it is positioned opposite the center of the tire tread in the width direction, so in all of these states the surface temperature at the center of the tire tread in the width direction (hereinafter referred to as tire surface temperature) is detected (measured). In contrast, when the steering angle is turned to the right to a certain extent or more, i.e., when turning to the right, as shown in Figure 6d, the front wheel tire surface temperature sensor 28 faces the outer part of the tire 3's tread in the width direction, so the tire surface temperature of the outer part of the tire 3's tread (outer tread turning portion) is detected (measured). Similarly, when the steering angle is turned to the left to a certain extent or more, i.e., when turning to the left, as shown in Figure 6e, the front wheel tire surface temperature sensor 28 faces the outer part of the tire 3's tread in the width direction, so the tire surface temperature of the outer part of the tire 3's tread turning portion is detected (measured). If the front wheel tire surface temperature sensors 28 are similarly positioned on the rear side of the two front wheels 2FR and 2FL, the tire surface temperature of the inner part of the tire 3's tread turning portion can be detected (measured) during right turns and left turns. The tire surface temperature detected (measured) by the front wheel tire surface temperature sensor 28 is acquired by the alignment state detection unit 7.

[0012] The tire surface temperature management device 4 has a processor 5 with advanced computational processing capabilities. The processor 5 includes a ROM (Read Only Memory) where programs are stored, a CPU (Central Processing Unit) that executes the programs stored in the ROM, and RAM (Random Access Memory) that functions as an accessible storage device. The processor 5 is equipped with a tire temperature estimation unit 6 and an alignment state detection unit 7 as functional units. The tire temperature estimation unit 6 includes a vehicle state acquisition unit 17, a heat generation amount calculation unit 8, a previous temperature acquisition unit 20, a road surface temperature acquisition unit 18, an ambient temperature acquisition unit 19, a heat dissipation amount calculation unit 9, a temperature change amount calculation unit 10, and a surface temperature calculation unit 11. The heat dissipation amount calculation unit 9 further includes a first heat dissipation amount calculation unit 9a and a second heat dissipation amount calculation unit 9b. The alignment state detection unit 7 includes a caster angle calculation unit 7a and a camber angle calculation unit 7b. These functional units operate when the CPU executes programs stored in the ROM within the processor 5.

[0013] The following describes the method for estimating the surface temperature of the tire 3 in the tire temperature estimation unit 6. The vehicle state acquisition unit 17 of the tire temperature estimation unit 6 acquires the steering angle δ of the vehicle 1 detected by the steering angle sensor 21 and the longitudinal acceleration (longitudinal acceleration) a of the vehicle 1 detected by the acceleration sensor 22. X and the acceleration (lateral acceleration) in the width direction (lateral direction) of vehicle 1 a Y , the driving speed V of vehicle 1 detected by speed sensor 23, and the braking force F detected by drive force sensor 24 XTTL The magnitude is obtained. Then, the vehicle state acquisition unit 17 acquires this information, namely the steering angle δ of vehicle 1 and the longitudinal acceleration a X , lateral acceleration a Y Vehicle 1's travel speed V, braking force F XTTL The magnitude of the vehicle state information is output to the heat generation calculation unit 8. The heat generation calculation unit 8 calculates the heat generation of the tires 3 of each wheel 2i based on the vehicle state information input from the vehicle state acquisition unit 17. The heat generation is calculated as follows. First, the heat generation calculation unit 8 calculates the vertical load (wheel load) of each wheel 2i based on the vertical acceleration and lateral acceleration. In the calculation, as shown in Figure 2a, the vertical acceleration aX [m / s 2 Change in vertical load ΔF due to ] Z-X [N] is calculated according to the following formula. In the formula, M[kg] is the mass of vehicle 1, L[m] is the wheelbase (farthest axle distance) of vehicle 1, H CG [m] is the height of the center of gravity of vehicle 1. Similarly, as shown in Figure 2b, the lateral acceleration a Y [m / s 2 Change in vertical load ΔF due to ] Z-Y [N] is calculated according to the following two formulas. In the formulas, D[m] is the tread of vehicle 1 (distance between the centers of the contact surfaces of the left and right wheels).

[0014]

number

[0015] Using these vertical load changes, the vertical load of each wheel 2i, i.e., the front right wheel load F, is calculated. ZFR [N], front left wheel load F ZFL [N], rear right wheel load F ZRR [N], rear left wheel load F ZRL [N] is calculated according to the following equations 3 to 6. Note that in the equations, L R [m] is the distance between the center of gravity and the rear axle of vehicle 1, L F [m] is the distance between the center of gravity and the front axle of vehicle 1.

[0016]

number

[0017] Furthermore, the heat generation calculation unit 8 calculates the total lateral force F of the vehicle 1 (all wheels 2i). YTTL [N] is distributed to each wheel 2i, and the lateral force of each wheel 2i, i.e., the lateral force F of the front right wheel, is distributed in this manner. YFR [N], Front left wheel lateral force F YFL [N], Rear right wheel lateral force F YRR [N], rear left wheel lateral force F YRL [N] is calculated according to equations 7-10 below. Note that the total lateral force F of vehicle 1 YTTL [N] represents the mass M [kg] of vehicle 1 and the lateral acceleration a Y [m / s 2It is the product of ].

[0018]

number

[0019] Furthermore, the heat generation calculation unit 8 calculates the braking and driving force F of the vehicle 1 (all wheels 2i). XTTL [N] is distributed to each wheel 2i, and the longitudinal force of each wheel 2i, i.e., the longitudinal force F of the front right wheel, is distributed in this manner. XFR [N], front left wheel longitudinal force F XFL [N], rear right wheel longitudinal force F XRR [N], rear left wheel longitudinal force F XRL [N] is calculated according to the following 11 equations. In the equations, DR is the braking and driving force distribution ratio to each wheel 2i, and the subscript i represents the position of the wheel 2i, i.e., FR for front right, FL for front left, RR for rear right, and RL for rear left.

[0020]

number

[0021] The heat generation calculation unit 8 then calculates the vertical force F of each wheel 2i. Xi [N] and vertical load F Zi Based on [N], the longitudinal heat storage coefficient (which is also the heat capacity) W of the tire 3 of each wheel 2i is determined by referring to a pre-stored map. Xi [N·m / ℃] is obtained. Similarly, the heat generation calculation unit 8 calculates the lateral force F of each wheel 2i. Yi [N] and vertical load F Zi Based on [N], the lateral heat storage coefficient (heat capacity) W of the tire 3 of each wheel 2i is determined by referring to a pre-stored map. Yi Obtain the [N·m / ℃] longitudinal heat storage coefficient of the tire 3 of each wheel 2i (hereinafter referred to as the tire longitudinal heat storage coefficient W). Xi and the lateral heat storage coefficient (tire lateral heat storage coefficient) W of the tire 3 of each wheel 2i YiThe map used to obtain the tire longitudinal heat storage coefficient W is a map created to reflect the fact that the heat generation amount QG of the tire 3 saturates when a large load (vertical load, longitudinal force and lateral force applied to the tire 3) greater than a predetermined value is applied to each tire 3. Therefore, the tire longitudinal heat storage coefficient W obtained by the heat generation amount calculation unit 8 is a map created to reflect the fact that the heat generation amount QG of the tire 3 saturates when a large load (vertical load, longitudinal force and lateral force applied to the tire 3) is applied to each tire 3. Xi and the lateral heat storage coefficient of the tire W Yi The heat generated by tire 3 QG increases with increasing load, but the rate of increase gradually decreases. i (See Figure 3) This value is affected by the inflection point. Note that, if the tires 3 of each wheel 2i have clear and identical specifications, as described later for the original tires, then the longitudinal heat storage coefficient W of each tire 3 is... Xi and the lateral heat storage coefficient W Yi Although this is the same for all wheels 2i, as will be described later, in this embodiment, in order to deal with unknown tires (different types of tires) whose specifications for each wheel 2i are unknown, the longitudinal heat storage coefficient W of the tire 3 is used. Xi and the lateral heat storage coefficient W Yi The subscript i is assigned to each wheel 2i to indicate its position.

[0022] Next, the heat generation calculation unit 8 calculates the heat generation QG of the tires 3 of each wheel 2i. i To calculate this, based on the steering angle δ and travel speed V of vehicle 1, for example, from a two-wheeled model, the longitudinal slip speed V of each wheel 2i (tire 3) is used. SLPXi and lateral slip speed V SLPYi The vertical slip velocity V is calculated as shown in Figure 3. SLPXi and lateral slip speed V SLPYi and the longitudinal force F of each wheel 2i (tire 3) Xi and lateral force F Yi and the longitudinal heat storage coefficient of the tire W Xi and the lateral heat storage coefficient of the tire W Yi Using the following formula 12, the amount of heat generated between the tire 3 of each wheel 2i and the road surface (tire heat generation) QG is calculated. i Calculate [℃ / s]. Here, tire heat generation QG i As is clear from the units, the calculated tire heat output QG iThis represents the increase in tire temperature per unit time, or what can be called the tire temperature increase rate.

[0023]

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[0024] Next, the previous temperature acquisition unit 20 shown in Figure 1, as will be described later, takes the surface temperature of the tire 3 of each wheel 2i calculated by the surface temperature calculation unit 11 and returns it to the previous surface temperature (previous tire surface temperature) T of the tire 3 of each wheel 2i. 0i The temperature is obtained as [°C]. Note that the previous temperature acquisition unit 20 is the ambient temperature T detected by the ambient temperature sensor 26 and acquired by the ambient temperature acquisition unit 19. AIR The data from the previous tire surface temperature T 0i The initial value is obtained via CAN. That is, the previous tire surface temperature T 0i The initial value is the ambient temperature T AIR This is the previous tire surface temperature T obtained by the previous temperature acquisition unit 20. 0i Using this, the first heat dissipation amount calculation unit 9a in the heat dissipation amount calculation unit 9 calculates the first heat dissipation amount (first tire heat dissipation amount) QD1 of the tires 3 of each wheel 2i. i Calculate the [℃ / s]. First tire heat dissipation QD1 i As shown in Figure 3, this is the amount of heat dissipated from the tires 3 of each wheel 2i to the road surface, and the road surface temperature T obtained by the road surface temperature acquisition unit 18. ROAD The following 13 equations are used to obtain the result. Note that the road surface heat dissipation coefficient κ1 [1 / s] in the equation may be set to be larger as the road surface temperature decreases. In addition, the second heat dissipation amount calculation unit 9b in the heat dissipation amount calculation unit 9 uses the previous tire surface temperature T 0i Using this, the second heat dissipation amount (second tire heat dissipation amount) QD2 of the tire 3 of each wheel 2i is calculated. i Calculate the [℃ / s]. This is the heat dissipation of the second tire QD2. i This refers to the ambient temperature T obtained by the ambient temperature acquisition unit 19. AIR and tire internal temperature T INRiBased on the following formula (14), as shown in FIG. 3, it includes the heat dissipation amount QD21 (the first term on the right side of formula (14)) radiated from the tire 3 of each wheel 2i to the outside air and the heat dissipation amount QD22 (the second term on the right side of formula (14)) radiated from the tire 3 to the air inside the tire. Here, the outside air heat dissipation coefficient κ2 in the formula is set to be larger as the outside air temperature T AIR is smaller. Also, the internal heat dissipation coefficient κ3 in the formula may be set to be larger as the internal temperature of the tire T INRi is smaller.

[0025]

Equation

[0026] Here, as is clear from the units of the first tire heat dissipation amount QD1 i and the second tire heat dissipation amount QD2 i , the calculated first tire heat dissipation amount QD1 i and the second tire heat dissipation amount QD2 i are the temperature decrease amount of the tire 3 per unit time, that is, what can be called the tire temperature decrease rate. Note that the value obtained by multiplying the difference value between the previous tire surface temperature T 0i and the outside air temperature T AIR by the outside air heat dissipation coefficient κ2, that is, only the first term on the right side of formula (14) may be used as the second tire heat dissipation amount QD2 i . Similarly, the value obtained by multiplying the difference value between the previous tire surface temperature T 0i and the internal temperature of the tire T INRi by the internal heat dissipation coefficient κ3, that is, only the second term on the right side of formula (14) may be used as the second tire heat dissipation amount QD2 i . Then, the temperature change amount calculation unit 10 subtracts the first tire heat dissipation amount QD1 i and the second tire heat dissipation amount QD2 i from the tire heat generation amount QG i and calculates the temperature change amount (tire temperature change amount) dT i / dt [°C / s] of the surface temperature of the tire 3 of each wheel 2i according to the following formula (15). Also, if formula (12) is substituted into the tire heat generation amount QG i in formula (15), the following formula (16) is obtained. Here, the tire temperature change amount dT iAs is clear from the unit / dt, the calculated tire temperature change amount dT i / dt represents the rate of change in tire temperature 3 per unit time, or the tire temperature change rate. The surface temperature calculation unit 11 in Figure 1 calculates the previous tire surface temperature T 0i and tire temperature change dT i Based on / dt, the surface temperature of each wheel 2i tire 3 (tire surface temperature T) i Calculate.

[0027]

number

[0028] The calculation process in the above-mentioned functional unit is shown in the flowchart of Figure 4. In the calculation process according to this flowchart, first in step S1, the heat generation unit 8 calculates the vertical load F of each wheel 2i according to equations 1 to 6 above. Zi Next, in step S2, the heat generation calculation unit 8 calculates the longitudinal force F of each wheel 2i according to equations 7 to 11 above. Xi and lateral force F Yi Next, in step S3, the heat generation calculation unit 8 calculates the vertical load F of each wheel 2i by referring to the map above. Zi and vertical force F Xi and lateral force F Yi The heat storage coefficient W of the tire 3 of each wheel 2i corresponds to X , W Y Next, in step S4, the heat generation calculation unit 8 calculates the slip speed V of each wheel 2i. SLPXi , V SLPYi Next, in step S5, the heat generation calculation unit 8 calculates the longitudinal force F of each wheel 2i according to the above equation 12. Xi and lateral force F Yi The heat storage coefficient W of the tire 3 of each wheel 2i X , W Y , slip speed V of each wheel 2i SLPXi , V SLPYi QG of tire heat generation for each wheel 2i according to the corresponding values i Next, in step S6, the road surface temperature acquisition unit 18 calculates the road surface temperature T ROADNext, in step S7, the ambient temperature acquisition unit 19 obtains the outside air temperature T AIR Next, in step S8, the ambient temperature acquisition unit 19 obtains the internal tire temperature T of each wheel 2i. INRi The following is obtained. Here, the processes in steps S6 to S8 may be executed in any order, or they may be executed simultaneously. Also, either step S7 or step S8 may be performed alone. Next, in step S9, the heat dissipation amount calculation unit 9 obtains the previous tire surface temperature T 0i and road surface temperature T ROAD Using the above formula 13, the heat dissipation QD1 of the first tire of each wheel 2i i In addition to calculating the previous tire surface temperature T 0i and outside air temperature T AIR and tire internal temperature T INRi Using the above formula 14, the heat dissipation QD2 of the second tire of each wheel 2i i The following is calculated. As mentioned above, the heat dissipation amount of the second tire QD2 i This may be only the first term on the right-hand side of the above equation 14, or only the second term. Next, in step S10, the temperature change amount calculation unit 10 calculates the tire heat generation amount QG i , 1st tire heat dissipation QD1 i , and the heat dissipation of the second tire QD2 i Using the above equations 15 to 16, the change in tire temperature dT of each wheel 2i i / dt is calculated. Then, in step S11, the surface temperature calculation unit 11 calculates the previous tire surface temperature T of each wheel 2i. 0i and tire temperature change dT i Tire surface temperature T using / dt i Calculate.

[0029] Next, before explaining the calculation process performed by the alignment state detection unit 7, we will explain the alignment state detected by the alignment state detection unit 7 and the characteristics of the alignment state when it changes from a general standard state. In this embodiment, the caster angle and camber angle of the two front wheels 2FR and 2FL of the vehicle 1 are determined. Figure 7 is a schematic representation of the front left wheel 2FL, with the left half of the figure being a front view and the right half being a side view. The caster angle is the angle between the vertical line (the vertical axis of the vehicle 1) and the steering axis of the two front wheels 2FR and 2FL, the so-called kingpin, in the side view of the wheel, and the value is small in a standard vehicle. The distance between the intersection of the extension of the steering axis with the road surface and the contact point of the two front wheels 2FR and 2FL (their tires 3) is called the caster trail, and this caster trail acts as a restoring moment to the straight-line state on the two front wheels 2FR and 2FL. Therefore, the larger the caster angle, the greater the force required to steer the two front wheels 2FR and 2FL. The camber angle is the angle between the vertical line (the vertical axis of vehicle 1) and the widthwise centerlines of the two front wheels 2FR and 2FL (the vertical axis of the wheels) in the front view (rear view) of the wheel, and the value for a standard vehicle is very small. In a normal vehicle, the upper ends of the two front wheels 2FR and 2FL are tilted inward in the vehicle width direction, which is known as negative camber, and positive camber, where the upper ends of the two front wheels 2FR and 2FL are tilted in the opposite direction, will not be discussed here. When vehicle 1 is driving straight, if the upper ends of the two front wheels 2FR and 2FL are tilted inward in the vehicle width direction, then when vehicle 1 is turning, the contact condition of the front wheels 2FR and 2FL on the outside of the turn will be good, resulting in improved grip and better turning performance.

[0030] This section describes the tire surface temperature in the following cases: when the front two wheels (2FR, 2FL) are in their standard alignment state, when only the caster angle is significantly changed (large caster angle), when only the camber angle is significantly changed (large camber angle), and when both the caster angle and camber angle are significantly changed (large caster angle and large camber angle). Here, the standard alignment state is defined as the state when Vehicle 1 is sold (or is being sold) as a new car. Since the state in which Vehicle 1 (or a part of it) is the same as a new car is broadly referred to as "original," the standard alignment state is defined as the original state, the same as when the car was new. Furthermore, both the large caster angle and large camber angle are assumed to change similarly from the original state for the front two wheels (2FR, 2FL). Figure 8 shows, as an example, the tire surface temperature when continuously turning left with the steering wheel turned sharply to the left, for the standard state, large caster angle state, large camber angle state, and large caster angle and large camber angle state. The right column of Figure 8 shows the alignment state, and the left column shows the vehicle body and the state of the two front wheels 2FR and 2FL as viewed from the front of vehicle 1. In the left column of Figure 8, the tires 3 of the two front wheels 2FR and 2FL are shown with dark shading to indicate a high temperature state (high tire surface temperature) and no shading to indicate a low temperature state (low tire surface temperature), with the shading becoming darker as the tire surface temperature increases. The center column of Figure 8 shows the state of the two front wheels 2FR and 2FL as viewed from above of vehicle 1, and the tire surface temperatures of the two front wheels 2FR and 2FL detected by the front wheel tire surface temperature sensor 28 in that state. Since the vehicle is turning left, the front right wheel 2FR is the outer wheel during the turn, and the front left wheel 2FL is the inner wheel during the turn. However, as mentioned above, the front wheel tire surface temperature sensor 28 detects (measures) the tire surface temperature at the outer part of the tread during the turn, regardless of whether it is the outer or inner wheel during the turn. The range between low and high tire surface temperatures is classified into slightly high and moderate high temperatures, starting from the lowest temperature. Slightly high temperatures refer to temperatures that are slightly higher (greater) than the nearly uniform tire surface temperature within the width of the tread when the vehicle is moving straight. Furthermore, it is assumed that even at low tire surface temperatures, they are higher (greater) than the ambient temperature.First, in the standard alignment state (=stock state), the roll of the two front wheels (2FR, 2FL) is slightly greater than the roll of the vehicle body. As a result, the load on the outer part of the tread of both the outer and inner turning wheels increases, causing the outer part of the tread to become hot while the inner part remains cool. Using this standard state as a baseline, when the caster angle is increased, during steering, the tops of both the outer turning wheel (front right wheel 2FR) and the inner turning wheel (front left wheel 2FL) tilt inward. As a result, the roll of the two front wheels (2FR, 2FL) becomes equal to or slightly less than the roll of the vehicle body. Therefore, the load within the tread of the tires 3 of the two front wheels (2FR, 2FL) is somewhat distributed, resulting in a moderately high temperature on the outer part of the tread and a slightly high temperature on the inner part. On the other hand, when the camber angle increases from the standard state, as mentioned above, the outer turning wheel (front right wheel 2FR) has improved contact with the ground and the load is distributed within the tread, but the load on the outer part of the turning tread of the inner turning wheel (front left wheel 2FL) increases. As a result, the tire surface temperature on the outer part of the turning tread that is detected (measured) (hereinafter also referred to as the measured tire surface temperature) becomes slightly high (almost uniform within the width of the tread) for the outer turning wheel (front right wheel 2FR), and becomes high for the inner turning wheel (front left wheel 2FL), and although not measured, the inner part of the turning tread of the inner turning wheel (front left wheel 2FL) becomes low. Furthermore, when the caster angle and camber angle are larger than the standard state, the tire surface temperature becomes similar to a combination of the large caster angle and large camber angle states. As a result, the outer turning wheel (front right wheel 2FR) becomes slightly hot (almost uniformly within the width of the tread), while the outer part of the turning tread of the inner turning wheel (front left wheel 2FL) becomes moderately hot, and the inner part becomes slightly hot. In this state, where both the caster angle and camber angle of the front left and right wheels are greater than the predetermined values, straight-line stability and turning performance are improved solely by the alignment state, resulting in nimble vehicle behavior even at high speeds. Therefore, here, the alignment state that combines a large caster angle and a large camber angle is defined as the ideal state.

[0031] If the alignment state can be detected in this way, the actual caster angle and camber angle of the two front wheels (2FR, 2FL) can be determined as follows. For example, in the case of a large caster angle, the difference between the measured high tire surface temperature (of the outer turning wheel) in the standard state and the measured moderately high tire surface temperature (of the outer turning wheel) in the large caster angle state is the increase from a predetermined value of the caster angle. Similarly, in the case of a large camber angle, the difference between the measured high tire surface temperature (of the outer turning wheel) in the standard state and the measured slightly high tire surface temperature (of the outer turning wheel) in the large camber angle state is the increase from a predetermined value of the camber angle. In the ideal state, the difference between the measured high tire surface temperature of the inner turning wheel in the standard state and the measured moderately high tire surface temperature of the inner turning wheel in the ideal state becomes the increase from a predetermined value of the caster angle, and the difference between the measured high tire surface temperature of the outer turning wheel in the standard state and the measured slightly high tire surface temperature of the outer turning wheel in the ideal state becomes the increase from a predetermined value of the camber angle. As mentioned above, a larger caster angle improves straight-line stability. In this example, the electric power steering system 12 improves the straight-line stability of the vehicle 1 by reducing the steering assist force as the vehicle's speed increases. When the caster angles of the two front wheels (2FR, 2FL) increase and straight-line stability improves, there is a risk that the straight-line stability improvement control by the electric power steering system 12 may become excessive. Therefore, according to the calculated caster angle, the straight-line stability improvement control by the electric power steering system 12 is reduced, that is, corrected to restore the steering assist force that would normally be reduced. Here, as shown in Figure 9, when the caster angle exceeds the first caster angle threshold (first threshold in the figure), the correction amount for straight-line stability improvement control begins to increase, and the correction amount for straight-line stability improvement control is increased linearly until the caster angle reaches the second caster angle threshold (second threshold in the figure). In the region where the caster angle is above the second caster angle threshold, the correction amount for straight-line stability improvement control is maintained at the correction amount at the second caster angle threshold. The first caster angle threshold is set to the caster angle at which the steering force required to turn the two front wheels (2FR, 2FL) becomes large, causing an unnatural feeling when steering the steering wheel.Furthermore, the second caster angle threshold was set to the caster angle at which straight-line stability is maximized as the caster angle increases, representing a characteristic of increasing caster angle. In other words, in principle, increasing the caster angle beyond the second caster angle threshold does not improve the straight-line stability of vehicle 1. On the other hand, in a normal vehicle 1, the adjustment range for the caster angle is limited, so the second caster angle threshold may be set to the maximum value of this caster angle adjustment range. To achieve this with the electric power steering device 12, the straight-line stability improvement control correction amount is set as follows. For example, steering torque T. S Steering assist force F A Output gain G A Using F A =G A f(T S )(f is steering torque T) S When given by a function of , as shown in Figure 10, in the region where the travel speed V is less than the straight-line stability improvement control start threshold V0, the output gain G A With this value set to 1, in the region where the travel speed V is equal to or greater than the straight-line stability improvement control start threshold V0, the output gain G increases with increasing travel speed V. A By reducing the angle k (<0) with a slope, the straight-line stability of vehicle 1 can be improved as the travel speed V increases. To minimize this straight-line stability improvement control, as shown in Figure 11, the output gain G is reduced in the region where the caster angle is less than the first caster angle threshold. A The slope (absolute value of) |k| is defined as k0, and in the region where the caster angle is greater than or equal to the first caster angle threshold, the output gain G increases with increasing caster angle. A The slope (absolute value of) |k| is linearly decreased, and in the region where the caster angle is greater than or equal to the second caster angle threshold, the output gain G A The slope (absolute value of) |k| is maintained at a constant value k1 again. The amount of straight-line stability improvement control correction at this second caster angle threshold can restore the steering assist force to its maximum, but it is more practical to set the upper limit to the amount of restoration that does not result in excessive steering assistance. This straight-line stability improvement control correction is performed using the caster angle calculated in relation to the assist torque calculated by the assist torque calculation unit 12a, after the caster angle has been calculated by the calculation process described later, which is performed by the alignment state detection unit 7.

[0032] On the other hand, increasing the camber angle improves turning performance. In this example, the vehicle behavior control device 13 improves the steering responsiveness of the vehicle 1 by promoting yawing motion based on the steering angle θ of the steering wheel and the vehicle's travel speed V. When the camber angles of the two front wheels (2FR, 2FL) increase and turning performance improves, the steering responsiveness improvement control by the vehicle behavior control device 13 may become excessive. Therefore, the steering responsiveness improvement control by the vehicle behavior control device 13 is corrected to be smaller according to the calculated camber angle. Here, as shown in Figure 12, when the camber angle exceeds the first camber angle threshold (first threshold in the figure), the amount of correction for steering responsiveness improvement control begins to increase, and the amount of steering responsiveness improvement control correction is increased linearly until the camber angle reaches the second camber angle threshold (second threshold in the figure). In the region where the camber angle is above the second camber angle threshold, the amount of steering responsiveness improvement control correction is maintained at the correction amount at the second camber angle threshold. The first camber angle threshold is set to a camber angle at which the vehicle 1's turning ability becomes overly sensitive to steering input from the steering wheel, resulting in an unnatural turning behavior of the vehicle 1. The second camber angle threshold is set to the camber angle at which the turning ability is maximized as the camber angle increases. In other words, in principle, increasing the camber angle beyond the second camber angle threshold does not improve the turning ability of the vehicle 1. On the other hand, since the adjustment range for the camber angle is limited in a normal vehicle 1, the second camber angle threshold may be set to the maximum value of this camber angle adjustment range. To realize this in the vehicle behavior control device 13, the steering response improvement control correction amount is set as follows. For example, the target yaw rate γ for steering angle θ and driving speed V. T Output gain G γ Using γ T =G γ When given by f(θ, V) (where f is a function of steering angle θ and driving speed V), as shown in Figure 13, in the region where the camber angle is less than the first camber angle threshold, the output gain G γ Initial value G γ0In the region where the camber angle is greater than or equal to the first camber angle threshold, the output gain G increases with increasing camber angle. γ By linearly decreasing the camber angle, the steering response of vehicle 1 can be reduced as the camber angle increases. Furthermore, in the region where the camber angle is greater than or equal to the second camber angle threshold, the output gain G γ Return to a constant value G γ1 This is maintained. The steering response improvement control correction amount at this second camber angle threshold can also be set to zero for the amount of control that enhances yawing motion, but it is more practical to set the upper limit to a control amount that does not make the vehicle's turning ability too sensitive. This steering response improvement control correction is performed using the camber angle calculated with respect to the target yaw rate calculated by the target yaw rate calculation unit 13a, after the camber angle has been calculated by the calculation process described later performed by the alignment state detection unit 7.

[0033] Next, the calculation process performed by the alignment state detection unit 7 in Figure 1 will be explained using the flowchart in Figure 14. This calculation process is executed, for example, by a timer interrupt process with a predetermined sampling period, and the flag F is reset to 0 before the vehicle 1 starts moving. In this calculation process, first, in step S21, it is determined whether the flag F is in the reset state of 0. If the flag F is in the reset state, the process moves to step S22; otherwise, it returns to the previous step. In step S22, it is determined whether the duration of the driving state is greater than or equal to a predetermined value. If the duration of the driving state is greater than or equal to the predetermined value, the process moves to step S23; otherwise, it returns to the previous step. This predetermined value for the duration of the driving state is the duration of the driving state required for the low tire surface temperature to become higher than the ambient temperature, as explained in Figure 8. In step S23, it is determined whether the steering angle of the steering wheel is greater than or equal to a predetermined value. If the steering angle is greater than or equal to the predetermined value, the process moves to step S24; otherwise, it returns to the previous step. The predetermined value of this steering angle may be either a right turn or a left turn, but as explained in Figure 8, it is set to the steering angle of the front two wheels 2FR and 2FL that allows the front wheel tire surface temperature sensor 28 to detect (measure) the tire surface temperature of the outer part of the tread turning of the front two wheels 2FR and 2FL. Note that the tire surface temperature at steering angles below this predetermined value, i.e., the tire surface temperature at the center of the tread width direction of tire 3, is always read. In step S24, it is determined whether the duration of turning after the steering angle has exceeded the predetermined value is equal to or greater than the predetermined value. If the duration of turning is equal to or greater than the predetermined value, the process proceeds to step S25; otherwise, the process returns to the previous step. The predetermined value of this duration of turning is, as explained in Figure 8, the duration of turning that is equal to or greater than the time required for the tire surface temperature of the outer part of the tread turning of the front two wheels 2FR and 2FL to reach the characteristic temperature for each alignment state. In step S25, the tire surface temperature of the outer part of the tread rotation of the two front wheels (2FR and 2FL) tires 3, detected (measured) by the front tire surface temperature sensor 28, is read as the actual measured front left and right tire surface temperature. Next, the process moves to step S26, where the tire surface temperature of the two front wheels (2FR and 2FL) tires 3, calculated by the surface temperature calculation unit 11, is read as the calculated front left and right tire surface temperature.Next, the process moves to step S27, where the alignment status of the front left and right wheels is detected (determined) according to the explanation in Figure 8 through individual calculation processes not shown. Next, the process moves to step S28, where it is determined whether the alignment status of the front left and right wheels is non-standard. If the alignment status of the front left and right wheels is non-standard, the process moves to step S29; otherwise, the process moves to step S34. In step S29, as described above, the caster angle and camber angle of the front left and right wheels are calculated using the measured surface temperature values ​​of the front left and right wheel tires. Next, the process moves to step S30, where it is determined whether the calculated caster angle is greater than or equal to the first caster angle threshold. If the caster angle is greater than or equal to the first caster angle threshold, the process moves to step S31; otherwise, the process moves to step S32. In step S31, the process instructs the electric power steering device 12 to correct the straight-line stability improvement control according to the caster angle, according to individual calculation processes not shown, and then the process moves to step S32. In step S32, it is determined whether the calculated camber angle is greater than or equal to the first camber angle threshold. If the camber angle is greater than or equal to the first camber angle threshold, the system proceeds to step S33; otherwise, it proceeds to step S34. In step S33, the system instructs the vehicle behavior control device 13 to correct the steering response improvement control according to the camber angle, according to individual calculation processes (not shown), and then proceeds to step S34. In step S34, the system returns to the set state of flag F (1).

[0034] According to this calculation process, when the tire surface temperature of the two front wheels (2FR, 2FL) is higher than the ambient temperature, and the tire surface temperature of the outer part of the tread rotation of the two front wheels (2FR, 2FL) rises to a temperature necessary for determining the alignment state, the measured tire surface temperature values ​​of the two front wheels (2FR, 2FL) detected (measured) by the front wheel tire surface temperature sensor 28 and the calculated tire surface temperature values ​​are read, and the alignment state of the front left and right wheels is detected (determined) according to the explanation in Figure 8. If the alignment state of the front left and right wheels is in the standard state, only the alignment state determination flag F is set. However, if the calculated caster angle is greater than or equal to the first caster angle threshold, the electric power steering device 12 is instructed to correct the straight-line stability improvement control according to the caster angle, and if the calculated camber angle is greater than or equal to the first camber angle threshold, the vehicle behavior control device 13 is instructed to correct the steering response improvement control according to the camber angle. Then, the electric power steering device 12 corrects the amount of control for straight-line stability improvement control according to the calculated camber angle, and the vehicle behavior control device 13 corrects the amount of control for steering response improvement control according to the calculated camber angle. In this case, even if the alignment state of the two front wheels (2FR, 2FL) is an ideal state with large caster and camber angles, the same corrections are made to the straight-line stability improvement control and the steering response improvement control, preventing excessive straight-line stability improvement control and steering response control.

[0035] Thus, in this embodiment, when the alignment state of the vehicle 1 is detected by the processor 5, the tire surface temperature of the tires 3 mounted on the two front wheels 2FR and 2FL whose alignment state should be detected is detected, and the alignment state is determined based on the comparison result of the tire surface temperatures during cornering. This makes it possible to detect or compensate for the alignment state even while the vehicle 1 is in motion. Furthermore, by determining the alignment status when the tire surface temperature is higher than the ambient temperature, it becomes possible to determine the alignment status with greater accuracy. Furthermore, by using the actual tire surface temperature measured by the front tire surface temperature sensor 28 to determine the alignment status, the alignment status can be determined simply and reliably. Furthermore, by positioning the front tire surface temperature sensor 28 on the front side of the two front wheels (2FR, 2FL) and facing the center of the tread width direction of the tire 3 when the vehicle is traveling straight, it becomes possible to determine the alignment state of the two front wheels (2FR, 2FL) whether the vehicle 1 is turning right or left. Furthermore, after a predetermined time has elapsed since the start of cornering, the tire surface temperature on the outer part of the tread during cornering is compared between the inner and outer wheels. If the tire surface temperature of the outer wheel is lower than that of the inner wheel, the alignment is determined to be a large camber angle state, where the camber angle is greater than a predetermined value. This makes it possible to detect a large camber angle state using only the tire surface temperature detected (measured) by the front wheel tire surface temperature sensor 28. Furthermore, by comparing the measured surface temperatures of the front left and right tires with the calculated surface temperatures of the front left and right tires, it becomes possible to determine the alignment status with greater accuracy. Furthermore, by calculating the surface temperature values ​​of the front left and right tires according to the driving conditions of vehicle 1, and using these calculated front left and right tire surface temperature values ​​to determine the alignment state, it becomes possible to determine the alignment state with even greater accuracy.

[0036] Furthermore, the system compares the measured tire surface temperature at the center of the tread's width direction with the measured and calculated tire surface temperature at the outer part of the tread's turning radius. If the measured tire surface temperature at the outer part of the tread's turning radius, for both the inner and outer turning wheels, exceeds a predetermined high temperature after a set time based on the measured tire surface temperature at the center of the tread's width direction, then the alignment is determined to be in a standard state where both the caster angle and camber angle are smaller than predetermined values. This allows for accurate detection of whether the alignment of the front two wheels (2FR, 2FL) is in its original factory state. Furthermore, if the measured tire surface temperature at the outer part of the tread during rotation, for both the inner and outer wheels, is greater than the calculated tire surface temperature and less than a predetermined high temperature after a predetermined time from the measurement state of the tire surface temperature at the center of the tread in the width direction, then the alignment state is determined to be a large caster angle state, where the caster angle is greater than a predetermined value. This allows for accurate detection of a large caster angle state for the two front wheels (2FR and 2FL). Furthermore, if the measured tire surface temperature of the inner wheel at the outer corner of the tread reaches a predetermined high temperature or higher than the calculated tire surface temperature after a predetermined time from the measurement state of the tire surface temperature at the center of the tread in the width direction, and the measured tire surface temperature of the outer wheel at the outer corner of the tread is a predetermined slightly high temperature around the calculated tire surface temperature, then the alignment state is determined to be a large camber angle state where the camber angle is greater than a predetermined value. This allows for accurate detection of a large camber angle state for the front two wheels (2FR, 2FL). Furthermore, if the measured tire surface temperature of the inner wheel at the outer part of the tread during rotation is greater than the calculated tire surface temperature and less than the predetermined high temperature after a predetermined time from the measurement state of the tire surface temperature at the center of the tread in the width direction, and the measured tire surface temperature of the outer wheel at the outer part of the tread during rotation is a predetermined slightly high temperature, approximately the same as the calculated tire surface temperature, then the alignment state is determined to be an ideal state where both the caster angle and camber angle are greater than predetermined values. This allows for accurate detection of whether the alignment state of the two front wheels (2FR, 2FL) is ideal.

[0037] Furthermore, if it is determined that the caster angle is large or in an ideal state, the control amount of the straight-line stability improvement control in vehicle 1 is corrected to be smaller the larger the caster angle. This prevents the straight-line stability of the straight-line stability improvement control from becoming excessive compared to the straight-line stability due to the large caster angle. Furthermore, the straight-line stability improvement control is initiated at a caster angle exceeding the first caster angle threshold, which is the point at which steering input begins to be affected, such as by increased steering wheel resistance. This allows for an appropriate start to the reduction correction of the straight-line stability improvement control. Furthermore, the correction of the straight-line stability improvement control is stopped at a second caster angle threshold that is greater than the first caster angle threshold and, for example, when the straight-line stability of vehicle 1 is maximized based solely on the caster angle. This makes it possible to appropriately terminate the reduction correction of the straight-line stability improvement control. Furthermore, if it is determined that the camber angle is large or in an ideal state, the control amount of the steering response improvement control in vehicle 1 is corrected to be smaller the larger the camber angle. This prevents the turning effect of the steering response improvement control from becoming excessive in relation to the turning effect due to the large camber angle. Furthermore, the steering response improvement control is initiated at a camber angle exceeding a first camber angle threshold, which is the point at which the turning ability of vehicle 1 begins to be affected, such as by making the vehicle 1's turning ability overly sensitive. This allows for an appropriate start to the reduction correction of the steering response improvement control. Furthermore, the steering response improvement control correction is stopped at a second camber angle threshold that is greater than the first camber angle threshold and where the turning ability of vehicle 1 is maximized based solely on the camber angle. This allows for an appropriate termination of the reduction correction of the steering response improvement control. The alignment detection and compensation system according to the embodiment has been described above, but the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible within the scope of the gist of the present invention. Another example of control to improve the straight-line stability of the vehicle 1 is that, for example, by applying a braking force to all wheels 2i that is imperceptible to the occupants, the swaying of the vehicle 1 can be suppressed, thereby improving straight-line stability. This can also be achieved by negative driving force, so it can be achieved by regenerating the drive motor or, if the drive source is the engine, by applying engine braking. Furthermore, if the suspension of the vehicle 1 is equipped with an electronically controlled shock absorber with variable damping force, increasing the damping force when the vehicle 1 turns suppresses the roll of the vehicle body, thereby suppressing the swaying of the vehicle 1 and improving straight-line stability. On the other hand, another example of control to improve the steering responsiveness of the vehicle 1 is that, for example, in a vehicle 1 in which the driving force distribution between the front and rear wheels can be adjusted, increasing the driving force distribution to the rear wheels improves turning performance. Furthermore, in electric power steering systems, improving responsiveness to steering input, such as by increasing the steering gear ratio, improves cornering ability (turning ability). Conversely to the example of the electronically controlled shock absorber mentioned earlier, reducing the damping force when vehicle 1 is turning improves road-following ability and thus improves cornering ability. [Explanation of symbols]

[0038] 1...Vehicle, 2i...Wheel, 3...Tire, 4...Tire surface temperature management device, 5...Processor (arithmetic processing unit), 6...Tire temperature estimation unit, 7...Alignment state detection unit, 7a...Caster angle calculation unit, 7b...Camber angle calculation unit, 8...Heat generation amount calculation unit, 9...Heat dissipation amount calculation unit, 10...Temperature change amount calculation unit, 11...Surface temperature calculation unit, 12...Electric power steering device, 13...Vehicle behavior control device, 28...Front wheel tire surface temperature sensor

Claims

1. A wheel alignment state detection method for detecting the wheel alignment state of a vehicle using a processing unit, A tire surface temperature detection step for detecting the surface temperature of a tire mounted on a wheel whose wheel alignment status is to be detected, A wheel alignment state detection method characterized by comprising: a wheel alignment state determination step of determining the state of the wheel alignment based on the comparison result of the surface temperature of the tire during turning.

2. The wheel alignment state detection method according to claim 1, characterized in that the wheel alignment state determination step determines the wheel alignment when the surface temperature of the tire is higher than the ambient temperature.

3. The wheel alignment state detection method according to claim 1, characterized in that the tire surface temperature detection step includes a tire surface temperature measurement reading step that reads the tire surface temperature measured by a temperature sensor.

4. The wheel alignment state detection method according to claim 3, characterized in that the temperature sensor is positioned on the front or rear side of the vehicle of the wheel whose wheel alignment state is to be detected, and is positioned opposite the center in the width direction of the tire tread when the vehicle is traveling in a straight line.

5. The wheel alignment state detection method according to claim 4, characterized in that the wheel alignment state determination step involves comparing the surface temperature of the tire on the outer part of the tread during the turn, measured after a predetermined time from the start of turning, between the inner wheel and the outer wheel, and determining that the wheel alignment state is a large camber angle state where the camber angle is greater than a predetermined value if the surface temperature of the tire on the outer wheel during the turn is smaller than the surface temperature of the tire on the inner wheel during the turn.

6. The system includes a surface temperature calculation step for calculating the surface temperature of the tire, The wheel alignment state detection method according to claim 4, characterized in that the wheel alignment state determination step determines the wheel alignment state by comparing the measured surface temperature of the tire with the calculated surface temperature of the tire.

7. The above surface temperature calculation step calculates the surface temperature of the tire according to the driving conditions of the vehicle, The wheel alignment state detection method according to claim 6, characterized in that the tire surface temperature detection step includes a tire surface temperature calculation value reading step for reading the calculated tire surface temperature.

8. The wheel alignment state detection method according to claim 6, characterized in that the wheel alignment state determination step involves comparing the measured surface temperature of the tire at the center of the tread in the width direction with the measured surface temperature of the tire at the outer turning portion of the tread and the calculated surface temperature of the tire, and determining that the wheel alignment state is a standard state in which both the caster angle and camber angle are smaller than predetermined values ​​if the surface temperature of the tire at the outer turning portion of the tread, for both the inner and outer turning wheels, is greater than a predetermined high temperature after a predetermined time period set in advance from the measured surface temperature of the tire at the center of the tread in the width direction.

9. The wheel alignment state detection method according to claim 8, characterized in that the wheel alignment state determination step determines that the wheel alignment state is a large caster angle state where the caster angle is greater than the predetermined value, when the surface temperature of the tire at the outer part of the tread during turning is greater than the surface temperature of the tire calculated after a predetermined time from the measurement state of the tire surface temperature at the center of the width direction of the tread, and less than the predetermined high temperature, for both the inner and outer wheels during turning.

10. The wheel alignment state detection method according to claim 8, characterized in that the wheel alignment state determination step determines that the camber angle is large, with the camber angle being larger than the predetermined value, when the surface temperature of the tire of the inner wheel in the outer part of the tread is greater than a predetermined high temperature, which is greater than the surface temperature of the tire calculated after a predetermined time from the measurement state of the tire surface temperature in the center in the width direction of the tread, and the surface temperature of the tire of the outer wheel in the outer part of the tread is a predetermined slightly high temperature, which is about the same as the calculated surface temperature of the tire.

11. The wheel alignment state detection method according to claim 8, characterized in that the wheel alignment state determination step determines that the wheel alignment state is an ideal state in which both the caster angle and the camber angle are greater than the predetermined value when the surface temperature of the tire of the inner wheel in the outer part of the tread is greater than the surface temperature of the tire calculated after a predetermined time from the measurement state of the surface temperature of the tire in the widthwise center of the tread and less than the predetermined high temperature, and the surface temperature of the tire of the outer wheel in the outer part of the tread is a predetermined slightly high temperature of approximately the calculated surface temperature of the tire.

12. A wheel alignment state compensation method characterized by comprising a straight-line stability improvement control correction step, in which, when the wheel alignment state detection method according to claim 9 or 11 determines that the caster angle is large or in the ideal state, the amount of control for the straight-line stability improvement control in the vehicle is corrected to be smaller the larger the caster angle.

13. The wheel alignment state compensation method according to claim 12, characterized in that the straight-line stability improvement control correction step starts the correction of the straight-line stability improvement control when the caster angle is greater than or equal to a first caster angle threshold at which steering input begins to have an effect.

14. The wheel alignment state compensation method according to claim 13, characterized in that the straight-line stability improvement control correction step stops the correction of the straight-line stability improvement control when the caster angle is greater than the first caster angle threshold and the straight-line stability of the vehicle is maximized at a second caster angle threshold.

15. A wheel alignment state compensation method characterized by comprising a steering response improvement control correction step, in which, when the wheel alignment state detection method according to claim 10 or 11 determines that the camber angle is large or in the ideal state, the amount of control for the steering response improvement control in the vehicle is corrected to be smaller the larger the camber angle.

16. The wheel alignment state compensation method according to claim 15, characterized in that the steering response improvement control correction step starts the correction of the steering response improvement control when the camber angle is greater than or equal to a first camber angle threshold at which the turning ability of the vehicle begins to be affected.

17. The wheel alignment state compensation method according to claim 16, characterized in that the steering response improvement control correction step stops the correction of the steering response improvement control when the camber angle is greater than the first camber angle threshold and the turning ability of the vehicle is maximized.

18. A wheel alignment status detection device that detects the wheel alignment status of a vehicle using a calculation processing unit, The wheel alignment state detection device is characterized in that the processing unit detects the surface temperature of the tire mounted on the wheel whose wheel alignment state is to be detected, and determines the wheel alignment state based on the comparison result of the surface temperature of the tire during turning.

19. A wheel alignment state compensation device characterized in that, when the wheel alignment state detection device according to claim 18 determines that the caster angle is large, the amount of control for the straight-line stability improvement control in the vehicle is reduced as the caster angle of the wheel whose wheel alignment state is to be detected increases.

20. A wheel alignment state compensation device characterized in that, when the wheel alignment state detection device according to claim 18 determines that the camber angle is large, the amount of control for the steering response improvement control in the vehicle is reduced as the camber angle of the wheel whose wheel alignment state is to be detected increases.

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