JP3448573B2 - Vehicle mass calculation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle mass calculating device for calculating a vehicle mass used for determining shift timing of an automatic transmission.

[0002]

2. Description of the Related Art In a shift control by an automatic transmission, in order to determine a shift timing according to a driver's intention, in addition to the accelerator pedal depression amount and the vehicle speed, the slope of a running road, the mass of the vehicle, etc. Control of shift timing is performed based on various factors.

At present, automatic transmissions are widely used not only in so-called private cars but also in commercial vehicles such as taxis and route buses. Among them, in the case of a private car, since the number of passengers is relatively small, the mass of the vehicle rarely changes significantly, and it is not necessary to treat the mass of the vehicle as a variable. However, in a large-sized vehicle such as a route bus, the vehicle mass changes greatly depending on the number of passengers and the like. Therefore, it is preferable to handle the vehicle mass as a variable even in the automatic shift control. Also, as private cars, minivan-type vehicles with a relatively large number of passengers have become popular, and it may be preferable to treat the vehicle mass as a variable. Further, in order to perform shift control with higher accuracy even for a normal sedan type vehicle, it is preferable to treat the vehicle mass as a variable.

As a method of measuring such a vehicle mass, a method of measuring based on the stroke amount of the suspension in a static state of the vehicle or a method of measuring based on a load sensor provided in the suspension can be considered. However, these methods limit the vehicle to a stationary state. Also, the sensor that detects the stroke amount is
It is not widespread and costs more.

A method based on the relationship between acceleration and driving force has been proposed as a method for measuring the vehicle mass while the vehicle is traveling. In this method, the vehicle mass is determined by the magnitude of the acceleration obtained when a predetermined driving force is generated. That is, when the acceleration at the predetermined driving force is large, it is determined that the vehicle mass is small, and when the acceleration is small, it is determined that the vehicle mass is large.

In Japanese Unexamined Patent Publication No. 6-147304, the acceleration of the vehicle when the accelerator pedal is depressed,
A technique for calculating the vehicle mass by a neural network that inputs time-series signals indicating the vehicle speed and the throttle valve opening is disclosed. Further, in Japanese Patent Laid-Open No. 6-201523, the acceleration and speed of the vehicle and the throttle valve opening are detected while the vehicle is traveling on a road with a constant gradient and the change in the throttle valve opening is small. A technique for measuring a vehicle mass by comparing two states having different valve opening degrees is disclosed.

[0007]

However, in such a method of measuring the vehicle mass while the vehicle is running, no consideration is given to the vibration of the drive system and the change of the road gradient, so that the vehicle mass is measured in the vehicle mass measurement result. However, there is a problem in that the vehicle mass may not be accurately measured due to the inclusion of noise due to changes in the road gradient, vibration of the drive system, and the like.

The applicant of the present invention has disclosed in Japanese Patent Laid-Open No. 2000-213981 a technique for accurately measuring a vehicle mass without being affected by a change in a road gradient.

An object of the vehicle mass calculating apparatus of the present invention is to more accurately calculate the vehicle mass even when the vehicle is traveling.

[0010]

Means for Solving the Problem and Its Action / Effect The vehicle mass calculating device of the present invention adopts the following means in order to achieve the above object.

The vehicle mass calculating apparatus of the present invention calculates acceleration in the longitudinal direction of the vehicle to obtain an acceleration signal and acceleration signal calculating means, and driving force of the vehicle by the prime mover to obtain a driving force signal. Force signal calculating means, acceleration signal processing means for removing the influence of road gradient from the acceleration signal and noise due to driving of the drive system to obtain a processed acceleration signal, and road gradient from the driving force signal. Driving force signal processing means for obtaining the processing driving force signal by removing the influence of noise due to the driving of the drive system and the processing acceleration signal and the power signal processing obtained by the acceleration signal processing means. And a vehicle mass calculating means for calculating the mass of the vehicle based on the processing driving force signal obtained by the means.

The relationship between the force acting on the vehicle and the acceleration of the vehicle is
Since it can be expressed by the equation of motion ((force acting on vehicle) = (mass of vehicle) × (acceleration of vehicle)), if the force acting on the vehicle and the acceleration of the vehicle are known, the mass of the vehicle can be calculated. In the mass calculation device of the present invention, the vehicle mass calculation means removes the influence of the road gradient from the acceleration signal and also removes the influence of noise associated with the driving of the drive system, and the influence of the road gradient from the driving force signal. Is calculated and the mass of the vehicle is calculated based on the processing driving force signal in which the influence of noise due to the driving of the drive system is removed, and the mass of the vehicle can be calculated more accurately. Here, the "driving force of the vehicle by the prime mover" means the driving force of the vehicle obtained by driving the prime mover, and also includes the case where the vehicle is driven by the power obtained from the prime mover via a power transmission device such as a torque converter. Be done.

In the vehicle mass calculating device of the present invention, the acceleration signal processing means includes a first high-pass filter for removing a band below a predetermined frequency and a first notch filter for removing a predetermined frequency band. The driving force signal processing means removes a band below a predetermined frequency.
Of the high pass filter and the second notch filter for removing a predetermined frequency band.

Further, in the vehicle mass calculating device of the present invention, the acceleration signal processing means includes a first low-pass filter for removing a band of a predetermined frequency or higher for removing the influence of high frequency noise from the acceleration signal, The driving force signal processing means may include a second low-pass filter for removing a band of a predetermined frequency or higher for removing the influence of high frequency noise from the driving force signal.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to examples. The equation of motion in the longitudinal direction of the vehicle is
Let M be the mass of the vehicle, α be the acceleration, Fd be the driving force of the vehicle obtained as a prime mover from the engine through a torque converter, the running resistance Fr of the vehicle, g is the gravitational acceleration, and Θ be the road gradient. Can be represented.

[0016] M × α = Fd−Fr−Mgsinθ (1) M = (Fd−Fr) / (α + gsinθ) (2)

The vehicle mass device of the embodiment calculates the vehicle mass M based on the equation (2). FIG. 1 is a block configuration diagram showing configuration blocks of a vehicle mass calculation device according to an embodiment of the present invention. As shown, the vehicle mass detection device of the embodiment calculates a driving force calculation unit 10 that calculates a driving force Fd of a vehicle obtained from an engine via a torque converter and the like, and a running resistance Fr based on the running of the vehicle. A force obtained by subtracting the traveling resistance Fr calculated by the traveling resistance calculation unit 20 from the driving resistance Fd calculated by the traveling resistance calculation unit 20 and the driving force Fd calculated by subtracting the traveling gradient Fr from the force acting on the vehicle ( Hereinafter, the net driving force F (Fd-F
r)), an acceleration calculation unit 36 for calculating the acceleration α of the vehicle, and a predetermined noise for a signal representing the net driving force F calculated by the net driving force calculation unit 26. Lowpass filter 2 to remove
8, a notch filter 30, a high-pass filter 32, and a low-pass filter 3 that removes predetermined noise from the signal representing the acceleration α calculated by the acceleration calculation unit 36.
8, a notch filter 40, a high-pass filter 42, and a net driving force F from which predetermined noise is removed by each filter.
And a vehicle mass calculator 44 that calculates the vehicle mass M based on the acceleration α and the acceleration α. Each of these calculation units is actually a CPU that operates according to a predetermined program, and each storage unit is a storage device such as a ROM.

For the driving force Fd of the vehicle, for example, the engine output is calculated from the engine speed and the operation amount required by the driver such as the opening degree of the throttle valve and the depression amount of the accelerator pedal, and the gear ratio of the automatic transmission is calculated. The output to the drive wheels can be obtained from the total gear ratio of the drive system and the gear change efficiency such as the gear ratio of the differential gear and the differential gear, and the driving force Fd of the vehicle by the engine at the drive wheels can be calculated from the tire effective radius. In the embodiment, the relationship between the engine output, the throttle valve opening from the throttle valve opening sensor 12, and the engine rotation speed from the engine rotation speed sensor 14 is stored in advance in the engine output storage unit 16 as a map, and the throttle is stored. The engine output corresponding to the map is read by inputting the valve opening degree and the engine speed, and the output to the drive wheels based on the gear ratio is calculated from the detected value from the gear position sensor 18, and the effective radius of the tire, etc. Then, the driving force Fd of the vehicle on the driving wheels is calculated. It should be noted that the driving force Fd of the vehicle is calculated in advance when the torque converter outputs a power from a prime mover such as an engine to driving wheels via a power transmission device such as a torque converter, unless the torque converter is in a direct connection state. The output torque of the torque converter can be calculated from the transfer characteristics of the torque converter (speed ratio, capacity coefficient, torque ratio, etc. of the torque converter) and the input speed of the torque converter, and can be used as the input torque of the automatic transmission. It can be calculated in the same manner as above. Here, the prime mover is not limited to an engine and may have any configuration such as a motor or a combination of a motor and an engine, and the power transmission device is not limited to a torque converter and may be a starting clutch or the like. In addition, the driving force Fd of the vehicle may be calculated based on the output (torque or rotation speed) detected by the sensor, the gear ratio of the differential gear, or the like by providing a sensor on the rotating shaft of the drive system such as a propeller shaft. A method can also be adopted. Also, the running resistance Fr
Is a sum of a frictional resistance such as rolling resistance that is not affected by the vehicle speed and an air resistance that is approximately proportional to the square of the vehicle speed. The running resistance storage unit 2 is obtained in advance as a characteristic of the vehicle.
If stored in No. 4, the corresponding running resistance Fr can be derived according to the running speed of the vehicle detected by the speed sensor 22. Strictly speaking, the rolling resistance of the running resistance Fr depends on the mass of the vehicle, but can be estimated by setting a representative value of the vehicle mass (for example, an average value of the fluctuating vehicle mass obtained by experiments). Is. In the method of setting the representative value of the vehicle mass such that the variation of the vehicle mass is large such as a road bus, when the error due to the rolling resistance becomes large, it is desirable to set the equation of motion by using the rolling resistance as a linear function of the vehicle mass M. . The acceleration α of the vehicle is calculated by the acceleration calculation unit 36 as a differential value of the speed of the vehicle detected by the speed sensor 22.
Of course, it can be obtained as the output of the acceleration sensor.

The low-pass filters 28 and 38 convert the signals representing the net driving force F calculated based on the detection by the engine speed sensor 14 and the speed sensor 22 and the acceleration α calculated based on the detection by the speed sensor 34, respectively. The filter is formed as a filter that removes a band having a predetermined frequency or higher in order to suppress the superimposed high frequency noise. By using the low-pass filters 28 and 38 to remove a band of a predetermined frequency or higher that can suppress high-frequency noise from the signals that appear in the net driving force F and the acceleration α, it is possible to obtain a motion equation that is not affected by high-frequency noise. it can.
The cutoff frequencies of the low-pass filters 28 and 38 are set to appropriate values by experiments or the like.

The notch filters 30 and 40 are superimposed on signals representing the net driving force F calculated based on the engine speed sensor 14 and the speed sensor 22 and the acceleration α calculated based on the speed sensor 34. In order to suppress noise due to torsional vibration of the rotary shaft of the drive system, it is formed as a filter that removes a predetermined frequency band. When the engine is driven, torsional vibration occurs in the rotary shaft of the drive system from the engine to the drive wheels. This torsional vibration resonates when rotated in accordance with the natural frequency of the rotating shaft,
It is superimposed as noise on a signal representing the acceleration α and the net driving force F. Therefore, the notch filter 3 for removing a predetermined frequency band matching the natural frequency of the rotary shaft of this drive system
By using 0 and 40, it is possible to obtain a motion equation that is not affected by the vibration of the rotary shaft of the drive system.
The frequency band removed by the notch filters 30 and 40 is set based on the characteristics of the rotary shaft of the drive system (characteristics such as torsion spring constant and moment of inertia).

The high-pass filters 32 and 42 are formed as filters for removing a band below a predetermined frequency in order to remove noise due to changes in the gradient of the road on which the vehicle is traveling. In the equation of motion of equation (2), the driving force Fd of the vehicle, the traveling resistance Fr, and the acceleration α other than the resistance due to the road gradient (gsin Θ) can be obtained from the traveling speed of the vehicle, the throttle valve opening, and the like. ,
Since the resistance due to the road gradient is not the characteristic of the vehicle body, it cannot be obtained based on the characteristic of the vehicle body. At this time, if the vehicle is traveling on a road with a constant gradient (θ = 0 on a flat road), in Equation (2), the term (gsinθ) applied to the gradient resistance is a constant, and the acceleration α is only a DC component. Affect. Therefore, by using the signal representing the acceleration α and the signal representing the net driving force F (F = Fd−Fr) excluding the DC component, it is possible to obtain a motion equation that is not affected by the constant gradient. However, although the road gradient is not constant but generally changes, the change is a relatively gradual change and affects only the low frequency component of the acceleration α. Therefore, for each of the signals representing the acceleration α and the net driving force F, a signal of a frequency equal to or lower than a predetermined frequency is removed to obtain an equation of motion that is not affected by the gradient even when the gradient changes. You can Moreover, if the high-pass filters 32 and 42 remove signals of a predetermined frequency or less, the DC component is also removed, so that the influence of the road gradient can be removed even when the road gradient is constant. The cutoff frequency of the high-pass filters 32 and 42 that can remove the influence of the road gradient is set to, for example, about 1 Hz based on the gradient change specified by the Road Structure Ordinance. Of course, the value is not limited to this, and an appropriate value may be set by a traveling experiment or the like.

The errors that cannot be removed by the low-pass filters 28, 38, the notch filters 30, 40, and the high-pass filters 32, 42 are removed by using a known method such as the recursive least squares method. Mass M
Can be estimated.

Next, in the vehicle mass calculating device of such an embodiment, a low-pass signal is obtained from the signal representing the net driving force F calculated by the net driving force calculating section 26 and the signal representing the acceleration α calculated by the acceleration calculating section 36. A simulation result of removing specific noise by the filters 28, 38, the notch filters 30, 40, and the high-pass filters 32, 42 will be described. FIG. 2 is a diagram illustrating the characteristics of a notch filter that removes the influence of torsional vibration of the rotary shaft of the drive system, and FIG. 3 is a diagram showing the notch filter of FIG. 2 in the acceleration signal after passing through the low-pass filter when starting uphill. It is a figure which illustrates the simulation result at the time of letting pass. In FIG. 3, the acceleration signal after passing through the low-pass filter 38 and before passing through the notch filter 40 shown by the broken line in FIG. 3 is oscillating. It is considered that this is due to a torsional vibration of the rotary shaft of the drive system and a detection error that occurs in the low rotation speed range immediately after starting because the resolution of the speed sensor 34 is not sufficient. At this time, it is understood that the vibration is improved as shown by the solid line in FIG. 3 by passing the acceleration signal through the notch filter 40. Next, FIG. 4 shows an example of simulation results of the acceleration force signal (Mα) based on the net driving force signal and the acceleration signal after passing through the low pass filter and the notch filter. The acceleration force signal (Mα) was simulated assuming that the vehicle mass M was known. As shown in FIG. 4, the waveform of the net driving force signal and the waveform of the acceleration force signal do not match. This is based on the fact that the acceleration force Mα is smaller than the net driving force F by the resistance due to the road gradient (Mgsin Θ) as shown in the equation of motion of equation (1). To remove this effect, a high-pass filter that removes a band below a predetermined frequency that affects the resistance due to the road gradient may be used.

FIG. 5 is a diagram exemplifying the characteristics of a high-pass filter for removing the influence of resistance due to road gradient.
FIG. 6 is a diagram illustrating a simulation result when a net driving force signal and an acceleration force signal are passed through the high pass filter of FIG. 5. As shown in FIG. 6, after passing through the high-pass filter, the net driving force signal F and the accelerating force signal Mα substantially match, and it can be seen that the influence of the road gradient is removed. That is, it is understood that the vehicle mass M can be calculated by dividing the net driving force F by the acceleration α. Note that, as shown in FIG. 5, a differential filter having substantially the same characteristics as the high-pass filter can be used instead of the high-pass filter.

According to the vehicle mass calculation apparatus of the embodiment described above, high-frequency noise, noise due to vibration of the rotating shaft of the drive system, and noise due to change in road gradient are used by using the low-pass filter, the notch filter, and the high-pass filter. Since the vehicle mass is calculated based on the removed acceleration signal and driving force signal, the vehicle mass can be calculated more accurately.

In the vehicle mass calculating apparatus of the embodiment, the signal representing the net driving force and the signal representing the acceleration are passed through the low pass filter, but if they can be removed by another method,
The low pass filter may not be used.

Although the embodiments of the present invention have been described with reference to the embodiments, the present invention is not limited to the embodiments of the present invention, and various embodiments are possible without departing from the gist of the present invention. Of course, it can be implemented in.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing configuration blocks of a vehicle mass calculation apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing an example of characteristics of a notch filter.

FIG. 3 is a diagram illustrating a simulation result of an acceleration signal after passing through a notch filter.

FIG. 4 is a diagram showing simulation results of driving force signals and acceleration force signals after passing through a low pass filter and a notch filter.

FIG. 5 is a diagram showing an example of characteristics of a high-pass filter and a differential filter.

FIG. 6 is a diagram showing simulation results of a driving force signal and an acceleration force signal after passing through a high pass filter.

[Explanation of symbols]

10 Driving Force Calculation Unit, 12 Throttle Valve Opening Sensor, 14 Engine Rotation Speed Sensor, 16 Engine Output Storage Unit, 18 Gear Speed Sensor, 20 Running Resistance Calculation Unit, 22 Speed Sensor, 24 Running Resistance Storage Unit, 26
Net driving force calculator, 28, 38 low-pass filter, 3
0,40 notch filter, 32,42 high-pass filter, 34 speed sensor, 36 acceleration calculation unit, 44 vehicle mass calculation unit.

Front page continuation (72) Masataka Osawa Inventor Masanori Nagakute-cho, Aichi-gun, Aichi 41 No. 1 Yokomichi Yokomichi Toyota Central Research Institute Co., Ltd. (72) Inventor Naoki Yamada 2-chome, Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd. (72) Inventor Minoru Ishiguro 2-1, Asahi-cho, Kariya City, Aichi Prefecture Aisin Seiki Co., Ltd. (72) Inventor Hiroaki Kato 2-chome, Asahi-cho, Kariya City, Aichi Prefecture Aisin Seiki Co., Ltd. (56) Reference literature JP-A-2000-213981 (JP, A) JP-A-2000-283831 (JP, A) Patent 3008111 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01G 19 / 03 G01G 19/02 G01G 19/08

Claims (3)

(57) [Claims] 1. An acceleration signal calculation means for calculating an acceleration in a longitudinal direction of a vehicle to obtain an acceleration signal, a driving force signal calculation means for calculating a driving force of the vehicle by a prime mover, and a driving force signal. An acceleration signal processing means for removing the influence of the road gradient from the acceleration signal and the influence of noise accompanying the driving of the drive system to obtain a processed acceleration signal; and a drive signal for removing the influence of the road gradient from the driving force signal. Driving force signal processing means for obtaining a processing driving force signal by removing the influence of noise accompanying driving of the system, processing acceleration signal obtained by the acceleration signal processing means, and processing drive obtained by the power signal processing means A vehicle mass calculation device, comprising: vehicle mass calculation means for calculating the mass of the vehicle based on the force signal. 2. The vehicle mass calculation device according to claim 1, wherein the acceleration signal processing means removes a band having a predetermined frequency or lower and a first notch filter removing a predetermined frequency band. And the driving force signal processing means includes a second high-pass filter that removes a band having a predetermined frequency or lower and a second notch filter that removes a predetermined frequency band. 3. The vehicle mass calculation device according to claim 1, wherein the acceleration signal processing means removes a band of a predetermined frequency or higher for removing the influence of high frequency noise from the acceleration signal. 5. The vehicle mass calculation device according to claim 1, wherein the driving force signal processing means includes a second low pass filter for removing a band having a predetermined frequency or higher for removing an influence of high frequency noise from the driving force signal.