JP3194763B2 - Method and apparatus for estimating vehicle speed in vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for estimating a vehicle speed in a vehicle having a driving wheel and a driven wheel.

[0002]

2. Description of the Related Art In automobiles and motorcycles, a so-called brake control device for controlling the wheel speed during braking by comparing it with the vehicle speed is used. In this brake control device, the slip rate is obtained from the wheel speed and the vehicle speed,
When the slip ratio is equal to or higher than the target slip ratio, the slip ratio is reduced by reducing the brake fluid pressure to obtain an optimal braking force.

There is also a driving force control device that controls the driving force by adjusting the ignition timing of the engine in response to sudden start or a change in the road surface friction coefficient. Also in this driving force control device, the wheel speed and the vehicle speed are used as data.

Incidentally, the wheel speed can directly detect the rotation speed of the wheel by a sensor, but it is difficult to directly detect the vehicle speed by a sensor. It is almost impossible with vehicles whose size is severely limited. Therefore, a method of estimating the vehicle speed from the wheel speed is usually employed.

[0005]

However, in a situation where the wheels slip on the road surface, the estimated vehicle speed may be set to be higher than the actual vehicle speed. In this case, the control in the brake control device or the driving force control device may be inappropriate.

Accordingly, an object of the present invention is to provide a method and apparatus for estimating a vehicle body speed in a vehicle, which can easily and accurately estimate a vehicle body speed required for brake control, driving force control, and the like. I do.

[0007]

In order to achieve the above object, the present invention provides a first step of determining wheel speeds of a driving wheel and a driven wheel, and a plurality of wheel speeds obtained in the first step. A second step of selecting a high-speed wheel speed,
The third step of estimating the vehicle body speed of the vehicle based on the wheel speed selected in the second step and the first to third steps are repeated at predetermined time intervals, and in the third step If the obtained estimated vehicle speed is higher than the wheel speed of the driven wheel obtained in the first step and lower than the wheel speed selected in the second step, And a fourth step of setting the obtained estimated vehicle speed as the estimated vehicle speed in the process.

Further, the present invention provides first wheel speed detecting means for detecting wheel speeds of driving wheels, second wheel speed detecting means for detecting wheel speeds of driven wheels, and the first and second wheel speed detecting means.
Wheel speed selecting means for selecting a high-speed wheel speed among the wheel speeds detected by the wheel speed detecting means, and estimating the vehicle body speed of the vehicle based on the wheel speed selected by the wheel speed selecting means. Vehicle speed estimating means, vehicle speed storing means for storing the vehicle speed estimated by the vehicle speed estimating means, vehicle speed stored in the vehicle speed storing means, detected by the second wheel speed detecting means Comparing means for comparing the calculated vehicle speed with the wheel speed of the driven wheel, and the vehicle body speed estimating means, when the vehicle speed is higher than the wheel speed of the driven wheel in the comparison result of the comparing means, It is characterized in that the vehicle speed is estimated with the amount of change in the speed toward the high-speed side being zero.

[0009]

According to the method and apparatus for estimating the vehicle body speed in a vehicle according to the present invention, a high-speed wheel speed is selected from the wheel speeds of the drive wheels and the driven wheels, and the vehicle speed is estimated from the wheel speeds. If the vehicle speed is higher than the wheel speed of the driven wheel, the vehicle speed is determined to be inappropriate and the vehicle speed obtained before is used as it is. In this way, the vehicle speed can be obtained without greatly deviating from the actual vehicle speed.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a vehicle speed estimating method and apparatus according to the present invention.

FIG. 1 is a block diagram showing the configuration of a vehicle speed estimating apparatus according to this embodiment. The apparatus includes a driven wheel rotation speed sensor 10 that detects a rotation speed of a driven wheel (for example, a front wheel of a motorcycle) and a drive wheel rotation speed sensor that detects a rotation speed of a drive wheel (for example, a rear wheel of a motorcycle). 12, the driven wheel rotational speed sensor 10 and the drive wheel rotational speed sensor 1
Wheel speed calculation circuits 14A and 14B for calculating wheel speeds based on the signals from
A, a wheel speed selection circuit (wheel speed selection means) for selecting the larger one of the wheel speeds from the wheel speeds A and 14B.
6, an estimated vehicle speed calculating circuit (vehicle speed estimating means) 18 for calculating an estimated vehicle speed based on the wheel speed selected by the wheel speed selecting circuit 16, and an estimated vehicle speed storing circuit (memory) for storing the estimated vehicle speed. Vehicle speed storage means)
And a comparator (comparing means) 22 for comparing the estimated vehicle speed stored in the estimated vehicle speed storage circuit 20 with the wheel speed of the driven wheel from the wheel speed calculation circuit 14A. In this case, the output from the comparator 22 controls the estimated vehicle speed calculation circuit 18.

The driven wheel rotation speed sensor 10 and the wheel speed calculation circuit 14A function as first wheel speed detection means, and the driven wheel rotation speed sensor 12 and the wheel speed calculation circuit 14B detect the second wheel speed detection circuit. Functions as a means.

The vehicle speed estimating apparatus of this embodiment is basically constructed as described above. Next, a method of estimating the vehicle body speed by this device will be described by taking a motorcycle as an example.

First, during traveling of the motorcycle, the driven wheel rotational speed sensor 10 and the drive wheel rotational speed sensor 12
Detects the rotation of the front wheel and the rear wheel, for example, as pulses from a rotary encoder or the like, and outputs the pulses to the wheel speed calculation circuits 14A and 14B. Wheel speed calculation circuit 14
A and 14B calculate the wheel speed V _WF of the driven wheel and the wheel speed V _WR of the drive wheel based on the pulse, and output these to the wheel speed selection circuit 16. The wheel speed V
_WF and V _WR can be obtained by counting the number of pulses from the driven wheel rotation speed sensor 10 and the driving wheel rotation speed sensor 12 and converting this to the peripheral speed of each wheel.

Next, the wheel speed selection circuit 16 selects the larger one of the wheel speeds V _WF and V _WR and outputs it to the estimated vehicle speed calculation circuit 18 as the wheel speed V _WM . That is, the reason for selecting the higher wheel speed is that the higher the wheel speed is, the closer to the actual vehicle speed, if the slip ratio between the road surface and the wheels does not fall below 0.

The estimated vehicle speed calculation circuit 18 basically operates at every predetermined calculation period Δt (for example, Δt = 3 ms)
The estimated vehicle speed _Vref is calculated as follows.

In the estimated vehicle speed calculation circuit 18, the motorcycle cannot be decelerated at -9.8 m / s ² (-1G) or less, and accelerated at +29.4 m / s ² (+ 3G) or more. That the lower limit deceleration G
_DEC is set to G _DEC = −9.8 m / s ² (1), and the upper limit acceleration G _ACC is set to G _ACC = + 29.4 m / s ² (2). Then, the wheel speed V _{WM (n)} is temporarily estimated.
Estimated vehicle acceleration / deceleration dV obtained as vehicle speed V _{ref (n)
ref (n) / dt (=} (V ref (n) -V ref (n-1)) / Δt) is the lower limit deceleration G _DEC above, the upper limit acceleration G _ACC in the following range, the estimated vehicle speed V _ref a _(n), that determine the _{V ref (n) = V WM} (n) ... (3). Note that (n) indicates a value in the n-th calculation.

The wheel speed V _{WM (n)} is _{calculated based} on the tentative estimated vehicle speed.
Estimated vehicle acceleration / deceleration dV _{ref (n)} obtained as degree V _{ref (n)}
When / dt is decelerated at or below the lower limit deceleration G _DEC , the estimated vehicle speed V _{ref (n)} is set as V _{ref (n)} = V _{ref (n−1)} −ΔG _DEC (4) Ask. Note that V _{ref (n-1)} is the previous calculation cycle Δ
indicates the estimated vehicle speed at t, and ΔG _DEC is a lower limit deceleration amount (ΔG _DEC = G _DEC) corresponding to the predetermined calculation cycle Δt.
.DELTA.t). In this case, equation (4) indicates that the wheel speed V
_{When WM (n)} is decelerated at a deceleration equal to or lower than the lower limit deceleration G _DEC , the deceleration of the estimated vehicle body speed V _ref is set to the lower limit deceleration G _DEC .

Similarly, the wheel speed V _{WM (n) is changed} to the tentative estimated vehicle body.
Estimated vehicle acceleration / deceleration dV obtained as speed V _{ref (n)
When ref (n)} / dt is accelerated at or above the upper limit acceleration G _ACC , the estimated vehicle speed V _{ref (n)} is calculated as follows: V _{ref (n)} = V _{ref (n−1)} + ΔG _ACC (5) ). Here, ΔG _ACC indicates an upper limit acceleration amount (ΔG _ACC = G _ACC · Δt) corresponding to the predetermined calculation cycle Δt. In this case, equation (5) indicates that when the wheel speed V _{WM (n)} is accelerated at an acceleration equal to or higher than the upper limit acceleration G _ACC , the acceleration of the estimated vehicle body speed V _ref is set to the upper limit acceleration G _ACC. Represents.

FIG. 2 shows the estimated vehicle speed obtained based on the above equations (3), (4) and (5) when the wheel speed V _WM indicated by the dotted line is supplied from the wheel speed selection circuit 16. _Vref is shown.

In this embodiment, the estimated vehicle speed _Vref is corrected by comparing the estimated vehicle speed _Vref obtained as described above with the wheel speed _VWF of the driven wheel. . This will be described with reference to FIG.

FIG. 3 shows a case where the driving force of the engine of the motorcycle is increased to accelerate the motorcycle. In this case, the wheel speed V _{WR of the} rear wheel, which is a driving wheel, rapidly increases with respect to the wheel speed V _WF of the front wheel, which is a driven wheel, because the rear wheel is idle at the beginning of acceleration. At this time, the wheel speed selection circuit 16 outputs the wheel speed V _WR of the drive wheel to the estimated vehicle speed calculation circuit 18 as the wheel speed V _WM in order to select the one with the larger wheel speed. Incidentally, the estimated vehicle speed calculating circuit 18 calculates the estimated vehicle speed V based on the wheel speed V _{WM.
If ref} is calculated as it is, an estimated vehicle speed _Vref far from the actual vehicle speed will be obtained.

Therefore, in this embodiment, the estimated vehicle speed _{Vref (n-1)} obtained by the previous calculation is temporarily stored in the estimated vehicle speed storage circuit 20, and the estimated vehicle speed _{Vref (n- 1)}
The comparator 22 compares the estimated vehicle speed V _{ref (n) with} the wheel speed V _{WF (n)} of the driven wheel for the current calculation.
Has been corrected.

That is, the comparator 22 compares the wheel speed V _{WF (n)} of the driven wheel with the estimated vehicle speed V _{ref (n− 1),} and determines that V _{ref (n−1)} > V _{WF (n)} and If V _{ref (n−1)} <V _{WM (n)} (6), an update prohibition signal for the estimated vehicle speed V _ref is output to the estimated vehicle speed calculation circuit 18. Therefore, the estimated vehicle speed _{Vref (n)} is output from the estimated vehicle speed calculation circuit 18 as the same as the previous estimated vehicle speed _{Vref (n-1)} .
FIG. 3 shows the estimated vehicle speed _Vref calculated in this manner.

In this case, when the wheel speed V _WR of the driving wheel becomes higher than the wheel speed V _{WF of the} driven wheel, the estimated vehicle speed V _WR
ref is made to follow the wheel speed _VWF of the driven wheel without following the one with the larger wheel speed. Driven wheel
Less the better the slips against the road surface, and can obtain the estimated vehicle speed V _ref close to the vehicle speed of the reality. As a result, the estimated vehicle speed V can be more accurately determined.
_ref can be calculated.

FIG. 4 shows the relationship between the wheel speed V _{WF of} the driven wheel, the wheel speed V _WR of the driven wheel, and the estimated vehicle speed V _ref calculated based on the present embodiment during the operation of the brake control device. Things. Brake control device, the estimated vehicle speed calculated slip ratio and a V _ref and the wheel velocity V _WF or V _WR, has been adjusted to deceleration control the braking force so that the slip ratio does not increase, the wheel speeds V _WF, V _WR is substantially of a vibration type as shown in FIG. Then, the wheel speed V _WM selected by the wheel speed selection circuit 16 is as shown by a dotted line in FIG. 4, and the estimated vehicle body speed V _ref calculated for this is macroscopically by analogy with the case of FIG. Looking at
It becomes like the solid line of FIG. When the estimated vehicle speed _Vref is reduced, the estimated vehicle speed _Vref is updated again, so that the estimated vehicle speed _Vref similar to that shown in FIG. 2 is obtained.

As described above, the estimated vehicle speed _Vref very close to the actual vehicle speed can be obtained, so that, for example, when performing brake control, stable and accurate control becomes possible. Further, not only the brake control but also the control of the driving force can be performed accurately. Furthermore, since this control can be realized with an extremely simple configuration, the program capacity can be reduced, and high-speed calculation can be performed. Therefore, the calculation can be performed in a shorter calculation cycle to improve the accuracy. It becomes possible.

[0028]

As described above, according to the method and apparatus for estimating the vehicle body speed in the vehicle of the present invention, it is possible to obtain a highly accurate estimated vehicle body speed in accordance with the actual vehicle body speed.
Using this estimated vehicle speed, for example, it is possible to perform brake control with high accuracy and to control driving force. Further, since the control itself is simple, the configuration is also simple, and high-speed operation can be performed by a simple program. Therefore, the number of operations can be increased,
This makes it possible to further improve the accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a vehicle speed estimation device for a vehicle according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a wheel speed selected by a wheel speed selection circuit in the device shown in FIG. 1 and an estimated vehicle speed by a basic calculation process in an estimated vehicle speed calculation circuit.

FIG. 3 shows the apparatus shown in FIG.
FIG. 7 is a diagram illustrating the relationship between the wheel speed of a drive wheel, a selected wheel speed, and an estimated vehicle body speed estimated and corrected based on these wheel speeds.

FIG. 4 is an explanatory diagram showing a relationship among a wheel speed of a driven wheel, a wheel speed of a drive wheel, a selected wheel speed, and an estimated vehicle body speed estimated and corrected based on the wheel speed of a driven wheel, a wheel speed of a driven wheel, and a brake control in the device shown in FIG.

[Explanation of symbols]

 Reference Signs List 10: driven wheel rotational speed sensor 12: drive wheel rotational speed sensor 14A, 14B: wheel speed calculation circuit 16: wheel speed selection circuit 18: estimated vehicle speed calculation circuit 20: estimated vehicle speed storage circuit 22: comparator

Continuation of the front page (56) References JP-A-63-184558 (JP, A) JP-A-63-180864 (JP, A) JP-A-49-89062 (JP, A) JP-A-3-96467 (JP) JP-A-60-50061 (JP, A) JP-A-1-249532 (JP, A) JP-A-53-100382 (JP, A) JP-A-53-134186 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T ^7/ 12-8/96 G01P 3/42

Claims (2)

(57) [Claims] A first step of obtaining wheel speeds of a driving wheel and a driven wheel; and a second step of selecting a high-speed wheel speed from a plurality of wheel speeds obtained in the first step. A third step of estimating the vehicle body speed of the vehicle based on the wheel speed selected in the second step; and the first to third steps are repeated at predetermined time intervals, and the third step If the estimated vehicle speed obtained in the above is higher than the wheel speed of the driven wheel obtained in the first process and lower than the wheel speed selected in the second process, A fourth process of setting the estimated vehicle speed obtained in the above as the estimated vehicle speed in the process, and a vehicle speed estimation method for a vehicle. 2. A first wheel speed detecting means for detecting a wheel speed of a driving wheel, a second wheel speed detecting means for detecting a wheel speed of a driven wheel, and the first and second wheel speed detecting means. Among the wheel speeds detected in the, the wheel speed selection means to select a high-speed wheel speed, based on the wheel speed selected by the wheel speed selection means,
Vehicle speed estimating means for estimating the vehicle speed of the vehicle; vehicle speed storing means for storing the vehicle speed estimated by the vehicle speed estimating means; vehicle speed stored in the vehicle speed storing means; Comparing means for comparing the wheel speed of the driven wheel detected by the wheel speed detecting means of the vehicle speed, and wherein the vehicle body speed estimating means is such that the vehicle speed is higher than the wheel speed of the driven wheel in the comparison result of the comparing means. An apparatus for estimating a vehicle body speed in a vehicle, wherein when the vehicle speed is high, the vehicle speed is estimated by setting a change amount of the estimated vehicle speed to a high speed side to zero.