JP2008260414A - Camber angle estimation device and vehicular control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of estimating the ground camber angle by adding the portion caused by the deformation of a tire. <P>SOLUTION: A camber angle estimation formula storage unit 134 keeps a calculation formula for estimating the ground camber angle of wheels. A camber angle estimation unit 110 estimates the ground camber angle by substituting the spring constant acquired by a spring constant acquisition unit 108 in the camber angle estimation formula kept therein. The spring constant acquisition unit 108 computes the longitudinal spring constant (Kv) of the tire based on the formula of the spring constant kept in a spring constant calculation formula storage unit 132 by using information on the pneumatic pressure of a tire acquired by a pneumatic pressure acquisition unit 102. A control unit 120 controls the behavior of a vehicle based on the estimated camber angle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for estimating a camber angle of a wheel and also relates to a technique for controlling a vehicle using the estimated camber angle.

  The angle that the vehicle wheel makes with respect to the vertical line of the ground is called the camber angle, and when this camber angle occurs, there is a problem that lateral force is applied to the wheel, affecting the straightness and turning performance during running. . Especially when turning, the camber angle changes according to the roll of the vehicle body due to centrifugal force. For many vehicles, the left and right wheels are attached to the vehicle body with a slight outward inclination (negative camber) and go straight. In addition, stability during turning is realized at the same time.

For example, Patent Document 1 proposes an electric power steering device that suppresses a change in steering response due to a gyro moment caused by a change in a camber angle of a tire and a rotation of a wheel. In this electric power steering apparatus, a roll angle θ is calculated, a camber angular velocity is calculated from a ratio (φ / θ) of a camber angle φ determined in advance with respect to the roll angle, and the gyro is based on the camber angular velocity. Calculate the moment. Patent Document 2 calculates a camber angle change amount from a detection value of a height sensor that detects a vertical distance (height) from a wheel center to a vehicle body using a data map storing a camber angle change amount of the wheel with respect to the height. And the technique which calculates the camber angle of each wheel is proposed.
JP 2006-123645 A JP 10-310042 A

  Conventionally, a technique for estimating a camber angle of a wheel has been proposed as in the above-described patent document. However, for example, the camber angle estimated from the detection value of the height sensor or the like is relative to the vehicle body, so it is difficult to estimate the ground camber angle in consideration of the deformation of the tire.

  Then, an object of this invention is to provide the technique which estimates the ground camber angle in consideration of the deformation | transformation part of a tire.

  In order to solve the above-described problem, a camber angle estimation apparatus according to an aspect of the present invention is a camber angle estimation apparatus that estimates a ground camber angle of a wheel, a spring constant acquisition unit that acquires a spring constant of a wheel, and an acquisition And a camber angle estimating means for estimating the ground camber angle of the wheel using the spring constant. According to this aspect, by estimating the ground camber angle of the wheel based on the spring constant of the wheel, it is possible to estimate the ground camber angle in consideration of the deformation of the tire.

  You may further provide the memory | storage means holding the camber angle estimation formula. The camber angle estimation means may estimate the ground camber angle by substituting the spring constant acquired by the spring constant acquisition means into the camber angle estimation formula held in the storage means. By using the camber angle estimation formula, the ground camber angle can be obtained by calculation, and the time required for estimation can be shortened.

  You may further provide the detection means which detects the air pressure of a wheel. The spring constant acquisition means may acquire the spring constant of the wheel by calculation from the air pressure detected by the detection means. Since the spring constant changes depending on the temperature in the air chamber of the tire, an accurate spring constant can be obtained by using the detected value of the air pressure at that time.

  Another aspect of the present invention is a vehicle control device. The vehicle control device is estimated by a spring constant acquisition unit that acquires a spring constant of a wheel, a camber angle estimation unit that estimates a ground camber angle of the wheel using the acquired spring constant, and a camber angle estimation unit. Camber angle control means for adjusting an actual ground camber angle based on the ground camber angle.

  According to this aspect, by adjusting the actual ground camber angle based on the ground camber angle estimated using the spring constant of the wheel, camber angle control can be realized in consideration of tire deformation.

  Yet another embodiment of the present invention is also a vehicle control device. The vehicle control device is estimated by a spring constant acquisition unit that acquires a spring constant of a wheel, a camber angle estimation unit that estimates a ground camber angle of the wheel using the acquired spring constant, and a camber angle estimation unit. Assist force control means for controlling the assist force for steering the wheel based on the ground camber angle.

  According to this aspect, by controlling the assist force for the steering of the wheel based on the ground camber angle estimated using the spring constant of the wheel, the behavior of the vehicle is stabilized and the driver's operation is effective. It is possible to assist.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the technique which estimates a ground camber angle in consideration of the deformation | transformation part of a tire.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating a vehicle control device 200 provided in the vehicle 10 according to the embodiment. The vehicle 10 includes a vehicle main body 12, and the vehicle main body 12 includes a right front wheel 14FR, a left front wheel 14FL, a right rear wheel 14RR, and a left rear wheel 14RL (hereinafter collectively referred to as “wheel 14” as necessary). Installed. The wheel 14 has a tire and a wheel, and a wheel rim formed in a cylindrical shape is provided on the outer periphery of the wheel, and the tire is assembled on the outer periphery of the wheel rim. Thus, a tire air chamber is formed in a region surrounded by the inside of the tire and the outer periphery of the wheel rim.

  The vehicle control device 200 according to the present embodiment includes wheel state detection units 16a, 16b, 16c, and 16d (hereinafter collectively referred to as “wheel state detection unit 16” as necessary), camber angle actuators 22a, 22b, 22c, and 22d. (Hereinafter collectively referred to as “camber angle actuator 22” if necessary), cornering force sensors 24a, 24b, 24c, 24d (hereinafter collectively referred to as “cornering force sensor 24” if necessary), load sensor 26a, 26 b, 26 c, 26 d (hereinafter collectively referred to as “load sensor 26” as necessary), a vehicle body side receiver 20, a motor 28, and an electronic control unit (hereinafter referred to as “ECU”) 100.

  The wheel state detection unit 16a is mounted on the right front wheel 14FR, the wheel state detection unit 16b is mounted on the left front wheel 14FL, the wheel state detection unit 16c is mounted on the right rear wheel 14RR, and the wheel state detection unit 16d is mounted on the left rear wheel 14RL. . The wheel state detection unit 16 has a tire valve and a unit main body. The unit main body has a battery and a base therein, and a processing device is provided on the base. The unit main body includes an air pressure sensor, a temperature sensor, a transmitter, a receiver, and the like inside, and the processing device generates wheel state information from detection results of the air pressure sensor, the temperature sensor, and the like. The battery supplies power to a base processing device or the like. For this reason, the wheel state detection unit 16 can detect the tire air pressure and the tire chamber temperature and wirelessly transmit the wheel state information without receiving power from the vehicle body 12. The unit main body is fixed to one end of the tire valve. The wheel state detection unit 16 is attached to the wheel 14 by fixing the tire valve to the wheel rim. The wheel state detection unit 16 periodically transmits wheel state information at a predetermined cycle such as once every several minutes.

  The vehicle body side receiver 20 receives the wheel state information wirelessly transmitted from the wheel state detection unit 16. The vehicle body side receiver 20 is connected to the ECU 100, and the wheel state information received by the vehicle body side receiver 20 is output to the ECU 100.

  The cornering force sensor 24a detects the cornering force received by the right front wheel 14FR. The cornering force sensor 24b detects the cornering force received by the left front wheel 14FL, the cornering force sensor 24c detects the cornering force received by the right rear wheel 14RR, and the cornering force sensor 24d detects the cornering force received by the left rear wheel 14RL. The cornering force sensor 24 may be composed of, for example, a strain sensor assembled to a bearing unit of the wheel 14. The cornering force sensor 24 outputs the detected cornering force value to the ECU 100.

  The load sensor 26a detects a load applied to the right front wheel 14FR. The load sensor 26b detects the load applied to the left front wheel 14FL, the load sensor 26c detects the load applied to the right rear wheel 14RR, and the load sensor 26d detects the load applied to the left rear wheel 14RL. The load sensor 26 outputs the detected wheel load value to the ECU 100. The wheel load can be estimated from the detection value of the stroke sensor.

  Based on the wheel state information transmitted from the wheel state detection unit 16, the cornering force value output from the cornering force sensor 24, and / or the wheel load value output from the load sensor 26, the ECU 100 It has a function to estimate the camber angle. Thus, ECU100 comprises the camber angle estimation apparatus which estimates the ground camber angle of the wheel 14 in cooperation with another sensor. ECU 100 may control the behavior of vehicle 10 based on the estimated ground camber angle.

  The camber angle actuator 22a is an actuator that adjusts the ground camber angle of the right front wheel 14FR. The camber angle actuator 22b adjusts the ground camber angle of the left front wheel 14FL, the camber angle actuator 22c adjusts the ground camber angle of the right rear wheel 14RR, and the camber angle actuator 22d adjusts the ground camber angle of the left rear wheel 14RL. . The camber angle actuator 22 is a camber angle adjusting means that can increase or decrease the ground camber angle, and is driven by an instruction from the ECU 100. The ECU 100 functions as a control unit that adjusts the actual ground camber angle based on the estimated ground camber angle.

  The motor 28 is an electric motor that generates assist torque for assisting sliding when a rack bar (not shown) slides in response to rotation of a steering wheel (not shown). The motor 28 rotates in accordance with a control signal output from the ECU 100, and assist torque corresponding to the rotation is transmitted to a rack bar (not shown) as a sliding force. The ECU 100 functions as control means for controlling the assist force for steering the wheel 14 based on the estimated ground camber angle.

  FIG. 2 is a functional block diagram of the vehicle control device 200. The ECU 100 includes an air pressure acquisition unit 102, a cornering force value acquisition unit 104, a wheel load value acquisition unit 106, a spring constant acquisition unit 108, a camber angle estimation unit 110, a control unit 120, and a storage unit 130. The control unit 120 includes a camber angle control unit 122 and an assist force control unit 124, and the storage unit 130 includes a spring constant calculation formula storage unit 132, a camber angle estimation formula storage unit 134, and a static no-load radius storage unit 136. . The air pressure acquisition unit 102 acquires air pressure information from the wheel state information received by the vehicle body side receiver 20. The cornering force value acquisition unit 104 acquires a cornering force value from the cornering force sensor 24. The wheel load value acquisition unit 106 acquires a wheel load value from the load sensor 26.

The spring constant calculation formula storage unit 132 stores a calculation formula for calculating the longitudinal spring constant (Kv) of the tire of the wheel 14. The formula for calculating the longitudinal spring constant (Kv) of the tire is expressed by the following formula (1).
Kv = α × air pressure + β (1)
Here, the air pressure is the air pressure in the tire chamber, and α and β are constants. α and β are fixed values, and are set by a test or the like before shipment.

  The spring constant acquisition unit 108 reads the calculation formula of the vertical spring constant (Kv) from the spring constant calculation formula storage unit 132, and substitutes the air pressure value acquired by the air pressure acquisition unit 102 into the calculation formula, so that the vertical spring A constant (Kv) is acquired.

  The camber angle estimation formula storage unit 134 stores a calculation formula for calculating the ground camber angle (CA) of the wheel 14. The ground camber angle (CA) is expressed by the following equation (2).

  Here, R is a tire static no-load radius, Fz is a wheel load value, Kv is a longitudinal spring constant, CF is a cornering force value, and a, b, c, d, e, f, g, h are Are constants. The constants a to h are set by a test or the like before shipment. The static no-load radius storage unit 136 stores the static no-load radius of the tire. In Formula (2), the ground camber angle can be estimated by taking into account the deformation of the tire, using the longitudinal spring constant (Kv) of the tire.

  The camber angle estimation unit 110 reads the ground camber angle (CA) estimation formula from the camber angle estimation formula storage unit 134 and substitutes the longitudinal spring constant (Kv) acquired by the spring constant acquisition unit 108 into the estimation formula. Thus, the ground camber angle is estimated. For example, compared with the case where the camber angle is estimated using a map or the like, the time taken to estimate the camber angle can be shortened by using the calculation formula.

  Further, by using the longitudinal spring constant (Kv) and taking into account the deformation of the tire, it is possible to estimate the ground camber angle with higher accuracy. Further, the longitudinal spring constant (Kv) of the tire changes according to the air pressure, and also changes due to, for example, a temperature change in the tire chamber during traveling. The spring constant acquisition unit 108 obtains a longitudinal spring constant (Kv) corresponding to the current tire air pressure by using Equation (1), so that a more accurate ground camber angle can be derived. Furthermore, it is also possible to obtain the camber angle of the wheel 14 during cornering by taking into account the deformation of the tire.

  For example, when the ground camber angle exceeds a normal predetermined range, the camber angle control unit 122 may control the camber angle actuator 22 so as to return the camber angle to the normal range. Since the camber angle can be estimated accurately, the camber angle can be adjusted accurately by the camber angle actuator 22. Thereby, stable vehicle travel can be realized.

  When the ground camber angle exceeds a normal predetermined range, the assist force control unit 124 may drive the motor 28 to control the assist force for steering the wheel 14. Since the camber angle can be accurately estimated, an optimum assist force can be applied to the steering wheel by the motor 28. Thereby, stable vehicle travel can be realized.

  FIG. 3 shows a flow of vehicle control by the vehicle control device 200. The air pressure acquisition unit 102 acquires air pressure information from the wheel state information transmitted from the wheel state detection unit 16 (S10). The spring constant acquisition unit 108 reads the spring constant calculation formula from the spring constant calculation formula storage unit 132, and acquires the longitudinal spring constant (Kv) of the tire by calculation using the acquired air pressure information (S12). The camber angle estimation unit 110 also obtains the static no-load radius (R) of the tire from the static no-load radius storage unit 136, the wheel load value (Fz) from the wheel load value acquisition unit 106, and the cornering force value acquisition unit 104. The cornering force value (CF) is acquired from each (S14).

  The camber angle estimation unit 110 reads the camber angle estimation formula from the camber angle estimation formula storage unit 134, substitutes the acquired value, and acquires the camber angle (CA) by calculation (S16). Thereby, it becomes possible to estimate the ground camber angle of the wheel 14 with high accuracy. If the estimated value of the camber angle is within a predetermined range (Y in S18), the behavior control of the vehicle is not performed, and if it is outside the predetermined range (N in S18), the control unit 120 controls the behavior of the vehicle. Is executed (S20). Thereby, appropriate behavior control of the vehicle can be realized based on the camber angle estimated with high accuracy.

  FIG. 4 shows the relationship between the camber angle estimated by the method of this embodiment and the actually measured camber angle. FIG. 4 shows that the estimated camber angle and the actually measured camber angle have a very high correlation, indicating that the accuracy of the estimated camber angle is very high. From the above test, it was proved that the estimation accuracy can be improved by considering the deformation of the tire in the estimation of the camber angle.

  The present invention is not limited to the above-described embodiments, and any combination of the elements of the embodiments as appropriate is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can be included in the scope of the present invention.

It is a figure which shows typically the vehicle control apparatus provided in the vehicle which concerns on an Example. It is a functional block diagram of a vehicle control device. It is a figure which shows the flow of the vehicle control by a vehicle control apparatus. It is a figure which shows the relationship between the camber angle estimated by the method of a present Example, and the measured camber angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle, 12 ... Vehicle main body, 14 ... Wheel, 16 ... Wheel state detection unit, 20 ... Car body side receiver, 22 ... Camber angle actuator, 24 ... Cornering Force sensor, 26 ... load sensor, 28 ... motor, 100 ... ECU, 102 ... air pressure acquisition unit, 104 ... cornering force value acquisition unit, 106 ... wheel load value acquisition unit, 108 ... Spring constant acquisition unit, 110 ... Camber angle estimation unit, 120 ... Control unit, 122 ... Camber angle control unit, 124 ... Assist force control unit, 130 ... Storage unit, 132... Spring constant calculation formula storage unit, 134... Camber angle estimation formula storage unit, 136... Static no-load radius storage unit, 200.

Claims (5)

A camber angle estimation device for estimating a ground camber angle of a wheel,
Spring constant acquisition means for acquiring the spring constant of the wheel;
Camber angle estimation means for estimating the ground camber angle of the wheel using the acquired spring constant;
A camber angle estimation apparatus comprising: It further comprises storage means for holding a camber angle estimation formula,
2. The camber angle estimation unit estimates a ground camber angle by substituting the spring constant acquired by the spring constant acquisition unit into a camber angle estimation formula held in the storage unit. The camber angle estimation apparatus described in 1. A detecting means for detecting the air pressure of the wheel;
The camber angle estimation device according to claim 1, wherein the spring constant acquisition unit acquires a spring constant of a wheel by calculation from the air pressure detected by the detection unit. Spring constant acquisition means for acquiring the spring constant of the wheel;
Camber angle estimation means for estimating the ground camber angle of the wheel using the acquired spring constant;
Camber angle control means for adjusting an actual ground camber angle based on the ground camber angle estimated by the camber angle estimation means;
A vehicle control device comprising: Spring constant acquisition means for acquiring the spring constant of the wheel;
Camber angle estimation means for estimating the ground camber angle of the wheel using the acquired spring constant;
Based on the ground camber angle estimated by the camber angle estimating means, assist force control means for controlling the assist force for steering the wheel;
A vehicle control device comprising: