JP2015051649A - Vehicular control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular control device which can always estimate the turning radius of a vehicle with an optimum method regardless of the state of the vehicle.SOLUTION: A vehicular control device for estimating the turning radius of a vehicle, includes: a first turning radius estimation unit which estimates a yaw rate on the basis of a steering angle of the vehicle to estimate the turning radius of the vehicle on the basis of the estimated yaw rate; a second turning radius estimation unit which estimates the turning radius of the vehicle on the basis of the detected actual yaw rate; an air pressure determination unit which determines the state of the air pressure of tires; and a selection unit which selects one of the first turning radius estimation unit and the second turning radius estimation unit in accordance with the air pressure state of the tires determined by the air pressure determination unit.

Description

  The present invention relates to a vehicle control device, and more particularly, to a vehicle control device that determines a turning radius of a host vehicle necessary for correctly detecting a vehicle traveling ahead and a stationary obstacle.

Examples of vehicle control devices for reducing the burden of driving operations and collision damage by the driver include adaptive cruise control (hereinafter referred to as “ACC”) and pre-crash safety system (hereinafter referred to as “PCS”). There is. The ACC performs control for automatically accelerating and decelerating to maintain a preset inter-vehicle distance when the vehicle is driven following a preceding vehicle on an expressway or an automobile exclusive road. When the PCS determines that there is a possibility of a collision with the preceding vehicle or a stationary obstacle, the PCS performs control to reduce the collision damage by warning the driver or assisting the brake. Do.
In such a vehicle control device such as ACC and PCS, it is necessary to estimate the turning radius of the host vehicle in order to correctly detect the preceding vehicle and a stationary obstacle. Currently, there are multiple estimation methods, each with advantages and disadvantages. However, there is only one kind of estimation method that is adopted in an actual vehicle.
For example, in the prior art (Japanese Unexamined Patent Application Publication No. 2009-119921), a method for estimating the turning radius of the vehicle based on the detected actual yaw rate and calculating the turning state of the vehicle is proposed.

JP 2009-119921 A

  However, in the vehicle control device that employs one kind of estimation method, the best estimation result is not always obtained, and there are cases where accurate estimation cannot be performed depending on the state of the vehicle. When an accurate turning radius cannot be estimated, unintended acceleration, deceleration control failure, or the like occurs due to failure to detect a vehicle or obstacle ahead.

  An object of this invention is to implement | achieve the vehicle control apparatus which can always estimate the turning radius of a vehicle by the optimal method irrespective of the state of a vehicle.

  The present invention is a vehicle control device that estimates a turning radius of a vehicle, and estimates a yaw rate based on a steering angle of the vehicle and estimates a turning radius of the vehicle based on the estimated yaw rate. A second turning radius estimating unit that estimates a turning radius of the vehicle based on the detected actual yaw rate, an air pressure determining unit that determines a state of tire air pressure, and the tire determined by the air pressure determining unit A selection unit that selects one of the first turning radius estimation unit and the second turning radius estimation unit according to an air pressure state is provided.

  According to the present invention, the vehicle turning radius is estimated by selecting one of the two turning radius estimators in accordance with the tire air pressure state. Therefore, the vehicle turning is always performed in an optimum manner regardless of the vehicle state. The radius can be estimated.

FIG. 1 is a system configuration diagram of a vehicle control device. (Example) FIG. 2 is a flowchart of control by the vehicle control device. (Example)

  Embodiments will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. In FIG. 1, a vehicle control device 1 that estimates a turning radius of a vehicle includes a steering angle sensor 2, wheel speed sensors 3 to 6, a yaw rate sensor 7, and tire pressure sensors 8 to 11. Yes.
The steering angle sensor 2 detects the steering angle of the steered wheels steered by the driver.
The front right wheel speed sensor 3 detects the wheel speed of the front right wheel: FR. The front left wheel speed sensor 4 detects the wheel speed of the front left wheel: FL. The rear right wheel speed sensor 5 detects the wheel speed of the rear right wheel: RR. The rear left wheel speed sensor 6 detects the wheel speed of the rear left wheel: RL.
The yaw rate sensor 7 detects the actual yaw rate of the vehicle (hereinafter referred to as “actual yaw rate”). The yaw rate is a speed at which the rotation angle in the turning direction of the vehicle changes.
The front right tire pressure sensor 8 detects the tire pressure of the front right wheel: FR. The front left tire pressure sensor 9 detects the tire pressure of the front left wheel: FR. The rear right tire pressure sensor 10 detects the tire pressure of the rear right wheel: RR. The rear left tire air pressure sensor 11 detects the tire air pressure of the rear left wheel: RL.

The vehicle control device 1 includes a first turning radius estimation unit 12, a second turning radius estimation unit 13, an air pressure determination unit 14, and a selection unit 15.
The first turning radius estimation unit 12 estimates the yaw rate based on the steering angle of the vehicle detected by the steering angle sensor 2 and estimates the turning radius of the vehicle based on the estimated yaw rate. The second turning radius estimation unit 13 estimates the turning radius of the vehicle based on the actual yaw rate detected by the yaw rate sensor 7.
The air pressure determination unit 14 determines the tire air pressure state detected by each tire air pressure sensor 8-11.
The selection unit 15 selects one of the first turning radius estimation unit 12 and the second turning radius estimation unit 13 in accordance with the tire pressure state determined by the air pressure determination unit 14. Specifically, when there is no abnormality in the tire air pressure state, the selection unit 15 selects the first turning radius estimation unit 12 and estimates the turning radius of the vehicle. On the other hand, when there is an abnormality in the tire air pressure state, the selection unit 15 selects the second turning radius estimation unit 13 and estimates the turning radius of the vehicle.
The vehicle control device 1 detects a preceding vehicle according to the turning radius estimated by the first turning radius estimation unit 12, or precedes according to the turning radius estimated by the second turning radius estimation unit 13. A vehicle is detected and preceding vehicle follow-up control (ACC) is executed.

  Here, a turning radius estimation method by the first turning radius estimation unit 12 and a turning radius estimation method by the second turning radius estimation unit 13 will be described.

  The first turning radius estimation unit 12 estimates the yaw rate of the host vehicle from the vehicle speed obtained from the steering angle of the vehicle, the wheel speed, and the stability factor. Then, the first turning radius estimation unit 12 calculates the turning radius from the estimated yaw rate.

The yaw rate is estimated by the following equation.
γ = (− θ / NL) * {U / (1 + K * U ² )}
However,
γ: Estimated yaw rate [deg / s]
θ: Steering angle [deg]
N: Overall steering gear ratio L: Wheelbase [m]
K: Stability factor U: Vehicle speed [m / s]

  For the overall steering gear ratio N, wheelbase L, and stability factor K, predetermined values for each vehicle are set in advance.

The turning radius is estimated by applying the following equation to the obtained yaw rate.
R = (V / 3.6) / {γ * (π / 180)}
Where R: Estimated turning radius [m]

  The second turning radius estimation unit 13 acquires the actual yaw rate of the vehicle by the yaw rate sensor 7 and calculates the turning radius.

The turning radius is estimated by applying the following formula.
R = (V / 3.6) / {γ ′ * (π / 180)}
However,
γ ′: actual yaw rate [deg / s]
V: Vehicle speed [km / h]

The turning radius estimation by the first turning radius estimation unit 12 estimates the turning radius according to the driver's steering detected by the steering angle sensor 2, and therefore follows the steering of the driver and the movement of the vehicle. Is good. This is advantageous when the turning state of the vehicle changes, such as at the entrance of a curve or S-curve. On the other hand, the estimation of the turning radius by the first turning radius estimator 12 has a problem that the accuracy of estimation decreases when the tire pressure deficiency or uneven wear occurs because the stability factor varies depending on the condition of the tire.
Further, the method of estimating the turning radius by the second turning radius estimating unit 13 is estimated based on the actual yaw rate of the vehicle detected by the yaw rate sensor 7, so that it is difficult to be affected by the tire air pressure and wear. On the other hand, the estimation of the turning radius by the second turning radius estimation unit 12 has a problem that the followability is inferior because the generation of the yaw rate is delayed from the steering of the driver.
Therefore, as described above, the vehicular control apparatus 1 constantly monitors the tire air pressure state by the air pressure determining unit 14, and when the tire air pressure state is normal, the first turning radius estimating unit 12 having excellent followability. When the tire's air pressure condition is abnormal, such as when there is a bias in the air pressure, switching to execute the estimation of the turning radius by the second turning radius estimation unit 13 is always an appropriate method. So that the turning radius can be estimated.

Next, the operation will be described.
As shown in FIG. 2, when the control is started (S1), the vehicle control device 1 determines the tire air pressure state detected by the tire air pressure sensors 8 to 11 by the air pressure determination unit 14 (S2), It is determined whether there is an abnormality in the air pressure state (S3).
In the determination (S3), when the determination is NO in the determination (S3), the vehicle control device 1 selects the first turning radius estimation unit 12 by the selection unit 15 and estimates the turning radius (first estimated radius) of the vehicle. (S4). In the determination (S3), when the abnormality is YES in the determination (S3), the vehicle control device 1 selects the second turning radius estimation unit 13 by the selection unit 15 and estimates the turning radius (second estimation radius) of the vehicle. (S5).
When the first turning radius estimation unit 12 estimates the turning radius (S4), the vehicle control device 1 detects the preceding vehicle according to the estimated turning radius, and executes the preceding vehicle following control (S6). Then, the process returns to the tire pressure state determination (S2).
Further, when the turning radius estimation unit 13 estimates the turning radius (S5), the vehicle control device 1 detects the preceding vehicle according to the estimated turning radius and executes the preceding vehicle follow-up control ( S6), the process returns to the tire pressure state determination (S2).

As described above, the vehicle control device 1 includes the first turning radius estimation unit 12 and the second turning radius estimation unit 13, and provides information on the steering angle, wheel speed, and actual yaw rate necessary for estimation of the turning radius. Obtained from the steering angle sensor 2, the wheel speed sensors 3 to 6, and the yaw rate sensor 7, the turning radius of the vehicle is estimated by the first turning radius estimation unit 12 or the second turning radius estimation unit 13.
Moreover, the vehicle control apparatus 1 includes an air pressure determination unit 14, acquires air pressure information from the respective tire air pressure sensors 8 to 11, and determines whether there is an abnormality in the tire air pressure state. The determination result is notified to the vehicle control device 1.
The vehicle control device 1 includes a selection unit 15, and when the determination result of the air pressure determination unit 14 is normal, the vehicle turning control device 1 selects the first turning radius estimation unit 12 to estimate the turning radius, and the determination result of the air pressure determination unit If there is an abnormality, the second turning radius estimation unit 13 is selected to estimate the turning radius, and the preceding vehicle following control is executed.

As a result, the vehicle control device 1 selects one of the two turning radius estimation units 12 and 13 in accordance with the tire air pressure state to estimate the turning radius of the vehicle. Therefore, the turning radius of the vehicle can always be estimated by an optimum method.
Further, the vehicle control device 1 always estimates the turning radius of the vehicle by an optimum method, detects the preceding vehicle according to the estimated turning radius, and executes the preceding vehicle follow-up control. It can be detected correctly. As a result, the vehicle control apparatus 1 can suitably execute the preceding vehicle following control.
In the above-described embodiment, the preceding vehicle is detected according to the estimated turning radius and the preceding vehicle following control (ACC) is executed. However, there is a possibility that the host vehicle may collide with an obstacle that is stationary. If it is determined that there is a pre-crash safety control (PCS) that reduces the collision damage by warning the driver or assisting the brake.

  The present invention can always estimate the turning radius of a vehicle in an optimum manner regardless of the state of the vehicle, and can perform other control that requires estimation of the turning state of the vehicle, such as a lane on a highway. The present invention can be applied to a lane keeping assist system for assisting in-running, an approach warning system for a rear vehicle when changing lanes, a parking assistance system, and the like.

DESCRIPTION OF SYMBOLS 1 Vehicle control apparatus 2 Steering angle sensor 3 Front right wheel speed sensor 4 Front left wheel speed sensor 5 Rear right wheel speed sensor 6 Rear left wheel speed sensor 7 Yaw rate sensor 8 Front right tire pressure sensor 9 Front left tire pressure sensor 10 Rear Right tire pressure sensor 11 Rear left tire pressure sensor 12 First turning radius estimation unit 13 Second turning radius estimation unit 14 Air pressure determination unit 15 Selection unit

Claims (2)

  A vehicle control device for estimating a turning radius of a vehicle, a first turning radius estimation unit that estimates a yaw rate based on a steering angle of the vehicle and estimates a turning radius of the vehicle based on the estimated yaw rate, and a detection A second turning radius estimation unit that estimates a turning radius of the vehicle based on the actual yaw rate, an air pressure determination unit that determines a tire air pressure state, and a tire air pressure state determined by the air pressure determination unit And a control section for a vehicle, comprising: a selection section that selects one of the first turning radius estimation section and the second turning radius estimation section.   The vehicle control device according to claim 1, wherein a preceding vehicle is detected according to the estimated turning radius, and preceding vehicle following control is executed.

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