JP5326562B2 - Turning behavior detection device, turning behavior detection method, and yaw rate estimation method - Google Patents

Description

  The present invention relates to a turning behavior detection device, a turning behavior detection method, and a yaw rate estimation method.

Conventionally, by comparing the estimated yaw rate calculated based on the vehicle speed and steering angle with the actual measured yaw rate detected by the sensor, it is determined whether the vehicle is oversteering or understeering, and the turning behavior of the vehicle is determined. There was something to control (see Patent Document 1).
JP 2007-246006 A

By the way, since the actually generated yaw rate is affected by the road surface friction coefficient, the estimated value of the yaw rate calculated based on the vehicle speed and the steering angle needs to be corrected according to the friction coefficient. However, since it is difficult to accurately detect the friction coefficient itself, it is difficult to estimate the yaw rate, and further to detect the turning behavior such as oversteer and understeer.
An object of the present invention is to accurately detect the turning behavior of a vehicle.

The vehicle behavior detection device according to the present invention detects the actual values of the vehicle speed, the tire lateral force of the steered wheels, and the yaw rate. When the detected vehicle speed is equal to or less than the predetermined value, the vehicle behavior detection device responds to the predetermined value and the tire lateral force. Then, the estimated value of the yaw rate is calculated, and the turning behavior of the vehicle is detected according to the difference between the calculated estimated value of the yaw rate and the actually measured value of the detected yaw rate.

  According to the vehicle behavior device of the present invention, the tire lateral force is used when calculating the estimated value of the yaw rate, so that it can be accurately estimated without being influenced by the road surface friction coefficient, and the turning behavior of the vehicle is also improved. It can be detected with high accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< First Embodiment >>
"Constitution"
FIG. 1 is a schematic configuration diagram of a steering-by-wire.
In the figure, reference numeral 1 denotes a steering wheel, which is connected to the steering shaft 2. Reference numerals 3L and 3R denote steering wheels, which are connected to the pinion shaft 7 through the knuckle arm 4, the tie rod 5, and the rack and pinion 6 in this order. Both the steering shaft 2 and the pinion shaft 7 are in a mechanically separated and unconnected state, and are respectively held rotatably by a housing or the like (not shown).
The steering shaft 2 is provided with a reaction force motor 8 that generates a pseudo steering reaction force in response to a steering operation by a driver. The pinion shaft 7 has a pinion shaft corresponding to the steering angle of the steering shaft 2. A turning motor 9 for turning 7 is provided.

  The steering shaft 2 is provided with a steering angle sensor 11 that detects the steering angle θs, and the pinion shaft 7 is provided with a turning angle sensor 12 that detects the turning angle θw. A hub sensor 13 for detecting the tire lateral force is provided in each of the left and right wheel hub units, and a vehicle speed sensor 14 for detecting the vehicle speed V is mounted on the output side of the transmission. A yaw rate sensor 15 that detects an actual measurement value γs of the yaw rate is provided on the body that is on the spring. The steering angle sensor 11 and the turning angle sensor 12 are configured to detect positive values when turning right and detect negative values when turning left.

The hub sensor 13 detects a tire lateral force by detecting a change in the displacement difference between the inner ring and the outer ring in the hub unit using, for example, a Hall element and a magnetized encoder. However, the present invention is not limited to this, and a strain gauge may be provided outside the bearing, and the tire lateral force may be detected by detecting deformation of the bearing.
Various signals detected by the steering angle sensor 11, the turning angle sensor 12, the hub sensor 13, the vehicle speed sensor 14, and the yaw rate sensor 15 are input to a controller 20 constituted by, for example, a microcomputer. The tire lateral force detected by the hub sensor 13 is inputted as a total value Yf.

As shown in FIG. 2, the controller 20 detects a turning angle control unit 21 that drives and controls the steering motor 9, a steering reaction force control unit 22 that drives and controls the reaction force motor 8, and the turning behavior of the vehicle. A turning behavior detection unit 23 and a turning behavior control unit 24 that controls the turning behavior of the vehicle are provided.
The turning angle control unit 21 inputs the steering angle θs of the steering shaft 2 and the turning angle θw of the pinion shaft 7 and controls the turning angle θw by driving the turning motor 9 according to the steering angle θw. .

The steering reaction force control unit 22 inputs the tire lateral force Yf and the vehicle speed V, and drives the reaction force motor 8 to control the steering reaction force Tr with respect to the steering operation. Specifically, the steering reaction force Tr is calculated according to the tire lateral force Yf with reference to the map of FIG. This map is set so that the steering reaction force Tr increases in proportion to the tire lateral force Yf.
As shown in FIG. 4, the turning behavior detection unit 23 includes an estimated value calculation unit 31 that calculates an estimated value γe of the yaw rate according to the tire lateral force Yf and the vehicle speed V, and the detected actual value γs and the calculated estimated value γe. And a determination unit 32 that determines the turning behavior of the vehicle according to the difference between the two.

The estimated value calculation unit 31 calculates an estimated value γe of the yaw rate according to the tire lateral force Yf and the vehicle speed V according to the following equation (1).
γe = {Yf × (L / Lr)} / (m × V) (1)
γe: Estimated value of yaw rate Yf: Steering wheel tire lateral force L: Wheelbase Lr: Distance between vehicle center of gravity and rear wheel axle m: Vehicle weight V: Vehicle speed

However, when the vehicle speed V is equal to or lower than the low speed predetermined value V1, the predetermined value V1 is substituted into the equation (1). This predetermined value V1 is a value of about 20 km / h, for example.
The above equation (1) will be described.
The vehicle motion equation of a general vehicle is expressed by the following equation (2).
may = Yf + Yr
Iγ = YfLf + YrLr (2)
ay: Lateral acceleration I: Yawing moment of inertia Yr: Rear wheel tire lateral force Lf: Distance between vehicle center of gravity and front wheel axle

At the time of steady turning (stable), it is expressed by the following equation (3).
may = Yf + Yr = mVγ
YfLf = YrLr (3)
If the above formula (3) is arranged, the following formula (4) is derived.
Yf {(Lf + Lr) / Lr} = mVγ (4)
Solving the equation (4) for γ leads to the equation (1).
When the actual measurement value γs is smaller than the estimated value γe and the difference Δγ is larger than the predetermined value Δγ1, the determination unit 32 determines that there is an understeer tendency, and the actual value γs is larger than the estimated value γe. When Δγ is larger than a predetermined value Δγ2, it is determined that there is an oversteer tendency.

FIG. 5 is a specific example of the oversteer tendency. For example, when the tire lateral force Yr of the rear wheel is saturated and the tire lateral force Yf of the front wheel increases due to load movement due to braking, the yaw rate increases and the oversteer tendency Become.
The turning behavior control unit 24 outputs a correction command for correcting the turning angle θw in a direction to suppress the understeer tendency or the oversteer tendency to the turning angle control unit 21, and accordingly, the steering reaction force Tr is generated. A correction command for correction is output to the steering reaction force control unit 22.

<Action>
Since the actually generated yaw rate is affected by the road surface friction coefficient, the estimated yaw rate calculated based on the vehicle speed V and the steering angle θs needs to be corrected according to the friction coefficient. However, since it is difficult to accurately detect the friction coefficient, it is difficult to accurately estimate the yaw rate.
Therefore, in the present embodiment, an estimated value γe of the yaw rate is calculated according to the tire lateral force Yf and the vehicle speed V according to the equation (1). Thus, by using the tire lateral force Yf, the yaw rate can be accurately estimated without being affected by the road surface friction coefficient. Therefore, the turning behavior of the vehicle can be detected with high accuracy.
However, when the vehicle speed V is less than or equal to the low predetermined value V1, the predetermined value V1 is substituted into the equation (1) to calculate the estimated value γe. That is, according to the above equation (1), the estimated value γe increases as the vehicle speed V decreases. Therefore, by providing a lower limit value for the vehicle speed V to be substituted, the estimation value γe is prevented from being maximized, and in accordance with the actual situation. An estimated value γe can be calculated.

《Application example》
In the present embodiment, the tire lateral force Yf is detected using a Hall element and a magnetized encoder. However, this type of hub sensor 13 can accurately detect the tire lateral force when the vehicle speed is extremely low. There is a possibility that Yf cannot be detected. Therefore, when the vehicle speed V is equal to or lower than the low speed predetermined value V1, the drive current of the steered motor 9 is detected, the rack axial force is detected, the pinion torque is detected, and these are used instead. The estimated value γe may be calculated. Thereby, even if the vehicle speed V is low, the estimation of the yaw rate can be continued.

  In this embodiment, the yaw rate estimated value γe is calculated according to the tire lateral force Yf and the vehicle speed V, but the present invention is not limited to this. That is, according to the equation (1), the vehicle weight m is also a variable element. Therefore, instead of setting the vehicle weight m as a fixed value, the vehicle weight m is detected based on the suspension stroke detected by the stroke sensor or the pitching state of the vehicle detected by the acceleration sensor, and this is also substituted into the above (1). The estimated value γe may be calculated. Similarly, since the distance Lr between the vehicle center of gravity and the rear axle is also a variable element, the vehicle center of gravity is detected based on the suspension stroke detected by the stroke sensor and the vehicle pitching state detected by the acceleration sensor. The estimated distance γe may be calculated by calculating the distance Lr from the wheel axle and also substituting it into (1). Thus, more accurate estimation can be performed by detecting the vehicle weight m and the vehicle gravity center point and reflecting them in the calculation of the estimated value γe.

  Further, in the present embodiment, the steering-by-wire has been described. Applicable. Furthermore, the present invention can be applied not only for detecting the vehicle behavior but also for simply estimating the yaw rate.

"effect"
From the above, the vehicle speed sensor 14 corresponds to “vehicle speed detection means”, the hub sensor 13 corresponds to “lateral force detection means”, the estimated value calculation unit 31 corresponds to “estimated value calculation means”, and the yaw rate sensor 15 corresponds to “ The determination unit 32 corresponds to “behavior detection means”.
(1) According to vehicle speed detecting means for detecting vehicle speed, lateral force detecting means for detecting tire lateral force of a steered wheel, vehicle speed detected by the vehicle speed detecting means, and tire lateral force detected by the lateral force detecting means The estimated value calculating means for calculating the estimated value of the yaw rate, the measured value detecting means for detecting the measured value of the yaw rate, the estimated value calculated by the estimated value calculating means, and the measured value detected by the measured value detecting means. Behavior detecting means for detecting the turning behavior of the vehicle according to the difference.
Thus, since the tire lateral force is used when calculating the estimated value of the yaw rate, it can be accurately estimated without being affected by the road surface friction coefficient, and the turning behavior of the vehicle can be detected accurately. it can.

(2) The estimated value calculating means calculates an estimated value of the yaw rate according to the vehicle speed detected by the vehicle speed detecting means and the tire lateral force detected by the lateral force detecting means, according to the following equation. The turning behavior detection device according to claim 1.
γe = {Yf × (L / Lr)} / (m × V)
γe: Estimated value of yaw rate Yf: Tire lateral force of steered wheel L: Wheelbase Lr: Distance between vehicle center of gravity and driven wheel axle m: Vehicle weight V: Vehicle speed When calculating the estimated value of yaw rate in this way Since the tire lateral force is used, it can be accurately estimated without being influenced by the road surface friction coefficient, and the turning behavior of the vehicle can be detected with high accuracy.

(3) When the vehicle speed detected by the vehicle speed detecting means is equal to or less than a predetermined value, the estimated value calculating means estimates the yaw rate according to the predetermined value and the tire lateral force detected by the lateral force detecting means. Is calculated.
Thus, by providing the lower limit value for the vehicle speed to be substituted, it is possible to prevent the estimated value from being maximized and to calculate the estimated value in accordance with the actual situation.
(4) It includes weight detection means for detecting vehicle weight, and the estimated value calculation means includes a vehicle weight detected by the weight detection means, a vehicle speed detected by the vehicle speed detection means, and a tire detected by the lateral force detection means. An estimated yaw rate is calculated according to the lateral force.
Thus, more accurate estimation can be performed by detecting the vehicle weight and reflecting it in the calculation of the estimated value.

(5) Center-of-gravity point detection means for detecting the center-of-gravity point of the vehicle is provided, and the estimated value calculation means includes the vehicle center-of-gravity point detected by the center-of-gravity point detection means, the vehicle speed detected by the vehicle speed detection means, and the lateral force detection An estimated value of the yaw rate is calculated according to the tire lateral force detected by the means.
Thus, more accurate estimation can be performed by detecting the center of gravity of the vehicle and reflecting it in the calculation of the estimated value.

(6) The actual values of the vehicle speed, the tire lateral force of the steered wheel, and the yaw rate are detected, the estimated value of the yaw rate is calculated according to the detected vehicle speed and the tire lateral force, and the calculated estimated value and the detected actual value are detected. The turning behavior of the vehicle is detected according to the difference.
Thus, since the tire lateral force is used when calculating the estimated value of the yaw rate, it can be accurately estimated without being affected by the road surface friction coefficient, and the turning behavior of the vehicle can be detected accurately. it can.
(7) The vehicle speed and the tire lateral force of the steered wheel are detected, and an estimated value of the yaw rate is calculated according to the detected vehicle speed and the tire lateral force of the steered wheel.
Thus, since the tire lateral force is used when calculating the estimated value of the yaw rate, it can be accurately estimated without being influenced by the road surface friction coefficient.

<< Second Embodiment >>
"Constitution"
In the second embodiment, a first-order lag low-pass filter is added to the process of calculating the estimated value γe. That is, the estimated value calculation unit 31 calculates the estimated value γe of the yaw rate according to the following equation (5).
γe = {{Yf × (L / Lr)} / (m × V)}
× (1/1 + Ts) ………… (5)

<Action>
The hub sensor 13 is attached to a hub unit that is unsprung, while the yaw rate sensor 15 is attached to a vehicle body that is sprung. Therefore, strictly speaking, a phase delay occurs in the actual yaw rate value γs detected by the yaw rate sensor 15 with respect to the estimated yaw rate value γe calculated according to the tire lateral force Yf. That is, this phase shift affects the determination of the turning behavior.
Therefore, in the present embodiment, the phase of the estimated value γe is made to coincide with the phase of the actually measured value γs by adding a first-order lag low-pass filter to the calculation process of the estimated value γe in accordance with the equation (5). Thereby, the phase shift between the estimated value γe and the actually measured value γs can be eliminated, and the determination accuracy of the turning behavior can be improved.

"effect"
(1) The swivel according to claim 1 or 2, wherein the estimated value calculation means includes a filter that matches the phase of the estimated value to be calculated with the phase of the actual value detected by the actual value detection means. Behavior detection device.
Thereby, the phase shift between the estimated value and the actually measured value can be eliminated, and the determination accuracy of the turning behavior can be improved.

It is a schematic structure of a steering-by-wire. It is a block diagram of a controller. It is a map used for calculation of steering reaction force. It is a block diagram of a turning behavior detection unit. It is a specific example of an oversteer tendency.

Explanation of symbols

3L, 3R Steering wheel 8 Reaction force motor 9 Steering motor 11 Steering angle sensor 12 Steering angle sensor 13 Hub sensor 14 Vehicle speed sensor 15 Yaw rate sensor 20 Controller 21 Steering angle control unit 22 Steering reaction force control unit 23 Turning behavior detection unit 24 Turning behavior control unit 31 Estimated value calculation unit 32 Determination unit

Claims (10)

A vehicle speed detecting means for detecting a vehicle speed, a lateral force detecting means for detecting a tire lateral force of a steered wheel, a vehicle speed detected by the vehicle speed detecting means, and a yaw rate according to a tire lateral force detected by the lateral force detecting means. According to an estimated value calculating means for calculating an estimated value, an actual value detecting means for detecting an actual value of yaw rate, an estimated value calculated by the estimated value calculating means, and a difference between the actual values detected by the actual value detecting means And a behavior detecting means for detecting the turning behavior of the vehicle ,
The estimated value calculating means calculates an estimated value of the yaw rate according to the predetermined value and the tire lateral force detected by the lateral force detecting means when the vehicle speed detected by the vehicle speed detecting means is less than or equal to a predetermined value. A turning behavior detecting device characterized by that. A vehicle speed detecting means for detecting a vehicle speed, a lateral force detecting means for detecting a tire lateral force of a steered wheel, a vehicle speed detected by the vehicle speed detecting means, and a yaw rate according to a tire lateral force detected by the lateral force detecting means. According to an estimated value calculating means for calculating an estimated value, an actual value detecting means for detecting an actual value of yaw rate, an estimated value calculated by the estimated value calculating means, and a difference between the actual values detected by the actual value detecting means A behavior detecting means for detecting the turning behavior of the vehicle, and a center of gravity detecting means for detecting the center of gravity of the vehicle ,
The estimated value calculating means calculates an estimated value of the yaw rate according to the vehicle gravity center detected by the gravity center detecting means, the vehicle speed detected by the vehicle speed detecting means, and the tire lateral force detected by the lateral force detecting means. A turning behavior detecting device characterized by that. A vehicle speed detecting means for detecting a vehicle speed, a lateral force detecting means for detecting a tire lateral force of a steered wheel, a vehicle speed detected by the vehicle speed detecting means, and a yaw rate according to a tire lateral force detected by the lateral force detecting means. According to an estimated value calculating means for calculating an estimated value, an actual value detecting means for detecting an actual value of yaw rate, an estimated value calculated by the estimated value calculating means, and a difference between the actual values detected by the actual value detecting means And a behavior detecting means for detecting the turning behavior of the vehicle ,
The estimated value calculating means calculates an estimated value of a yaw rate according to the vehicle speed detected by the vehicle speed detecting means and the tire lateral force detected by the lateral force detecting means according to the following equation: apparatus.
γe = {Yf × (L / Lr)} / (m × V)
γe: Estimated value of yaw rate
Yf: Tire lateral force of steered wheels
L: Wheel base
Lr: Distance between the vehicle center of gravity and the driven wheel axle
m: vehicle weight
V: Vehicle speed 2. The estimated value calculating means calculates an estimated value of a yaw rate according to a vehicle speed detected by the vehicle speed detecting means and a tire lateral force detected by the lateral force detecting means according to the following equation. Or the turning behavior detection apparatus of 2.
γe = {Yf × (L / Lr)} / (m × V)
γe: Estimated yaw rate Yf: Steering wheel tire lateral force L: Wheelbase Lr: Distance between vehicle center of gravity and driven wheel axle m: Vehicle weight V: Vehicle speed The estimated value calculation means, wherein the phase of the estimated value calculated in any one of claims 1-4, characterized in that it comprises a filter to match the measured value of the phase detecting of the actually measured value detecting means Swivel behavior detector. The estimated value calculating means calculates an estimated value of the yaw rate according to the predetermined value and the tire lateral force detected by the lateral force detecting means when the vehicle speed detected by the vehicle speed detecting means is less than or equal to a predetermined value. The turning behavior detection device according to any one of claims 2 to 5 , wherein Comprising weight detection means for detecting vehicle weight;
The estimated value calculating means calculates an estimated value of the yaw rate according to the vehicle weight detected by the weight detecting means, the vehicle speed detected by the vehicle speed detecting means, and the tire lateral force detected by the lateral force detecting means. The turning behavior detecting device according to any one of claims 1 to 6 , wherein the turning behavior detecting device is a turning behavior detecting device. It has a center of gravity detection means for detecting the center of gravity of the vehicle,
The estimated value calculating means calculates an estimated value of the yaw rate according to the vehicle gravity center detected by the gravity center detecting means, the vehicle speed detected by the vehicle speed detecting means, and the tire lateral force detected by the lateral force detecting means. turning behavior detecting apparatus according to any one of claims 1,3～7, characterized in that. Measure actual values of vehicle speed, tire lateral force of steered wheels, and yaw rate. When the detected vehicle speed is less than or equal to a predetermined value , calculate an estimated value of yaw rate according to the predetermined value and tire lateral force. A turning behavior detection method comprising detecting a turning behavior of a vehicle according to a difference between an estimated value of a measured yaw rate and a measured value of the detected yaw rate.
The vehicle speed and the tire lateral force of the steering wheel are detected, and when the detected vehicle speed is equal to or less than a predetermined value , an estimated value of the yaw rate is calculated according to the predetermined value and the tire lateral force of the steering wheel. Yaw rate estimation method.

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