JP6938996B2 - Road surface judgment device - Google Patents

Description

The present invention relates to a road surface determination device.

Conventionally, techniques for estimating the road surface friction coefficient and the road surface friction state have been proposed.

Patent Document 1 describes a technique for improving the estimation accuracy by using the front-rear acceleration that eliminates the influence of the gravity component due to the road surface gradient in the road surface friction state estimation device based on the vehicle front-rear acceleration during controlled driving. ..

Patent Document 2 detects and detects the maximum value of wheel acceleration obtained by differentiating the maximum value of the throttle opening and the wheel speed detection value from the start of acceleration to the determination of the road surface when accelerating from a running state of a certain vehicle speed or higher. A technique for determining the road surface by determining which region the value is in is described.

Japanese Unexamined Patent Publication No. 2013-28258 Japanese Unexamined Patent Publication No. 10-299529

With the technique described in Patent Document 1, the influence of the gravitational acceleration component cannot be removed if the controlled drive is started on a flat road and immediately after that, if the vehicle enters a slope. Further, since the road surface gradient is not always constant, there is a problem that the correction value based on the front-rear reference value is not correctly performed and the road surface friction state is not estimated correctly.

In the technique described in Patent Document 2, the wheel speed detection usually uses an electromagnetic pickup and a slit for detecting the rotational speed in which the convex teeth are arranged at equal intervals, and detects the approach of the convex teeth of the slit by the electromagnetic pickup. When is low, the backlash force of the electromagnetic pickup becomes small, so that speed detection is difficult, and the number of convex teeth is also limited. Therefore, the lower the rotation speed, the lower the wheel speed detection accuracy. As a result, there is a problem that the road surface cannot be determined unless the vehicle speed exceeds a certain level.

The present invention has been made in view of such a problem, and an object of the present invention is to determine a road surface with high accuracy without being affected by a road surface inclination and a speed (even at a low speed). It is to provide the technology to obtain.

In the present invention, the vibration detecting means for detecting the vibration component of the front-rear resonance of the vehicle engine, the detecting means for detecting the acceleration / deceleration torque of the engine of the vehicle, and the friction coefficient of the road surface are set to μ, and the vehicle specifications are predetermined. The torque reference value corresponding to the maximum value μ _{max of} μ that shifts from the tire grip state of the vehicle to the tire slip state on the high μ road including the dry road and the low μ road including the ice road obtained below is stored. A storage means, a gear stage detecting means for detecting the current transmission gear stage of the vehicle, a frequency storage means for storing the engine front-rear resonance frequency of the vehicle, and a collation means for collating the vibration component with the engine front-rear resonance frequency. The acceleration / deceleration torque at the time when the vibration component and the front-rear resonance frequency of the engine match with the torque reference value are compared, and the road surface on which the vehicle is traveling is the high μ road or the low μ. The determination means includes a determination means for determining whether or not the vehicle is a road, and the determination means reads out the drive shaft torsional resonance frequency corresponding to the detected transmission gear stage from the reference table, and the read out drive shaft torsional resonance frequency is the engine front-rear resonance. not run before SL-size constant in the case equal to the frequency, a road surface judgment device.

Further, the present invention has a detection means for detecting the throttle opening of the vehicle, a vibration detecting means for detecting the vibration component of the front-rear resonance of the engine of the vehicle at the time when the throttle opening changes, and a friction coefficient of the road surface of μ. _{The maximum value μ max of} μ that shifts from the tire grip state of the vehicle to the tire slip state on the high μ road including the dry road and the low μ road including the ice road, which are obtained in advance under the predetermined vehicle specifications. A storage means for storing the accelerator opening reference value corresponding to the above, a gear stage detecting means for detecting the current transmission gear stage of the vehicle, a frequency storage means for storing the engine front-rear resonance frequency of the vehicle, and the vibration component. And the matching means for collating the front-rear resonance frequency of the engine with the throttle opening at the time when the vibration component and the front-rear resonance frequency of the engine match with the throttle opening reference value, and the vehicle travels. The road surface is provided with a determination means for determining whether the road surface is the high μ road or the low μ road, and the determination means reads the drive shaft torsional resonance frequency corresponding to the detected transmission gear stage from the reference table. This is a road surface determination device that does not execute the determination when the read drive shaft torsional resonance frequency is equal to the engine front-rear resonance frequency .

In one embodiment of the present invention, the vibration detecting means includes an engine front-rear acceleration detecting means for detecting the front-rear acceleration of the engine of the vehicle, an on-spring front-back acceleration detecting means for detecting the front-back acceleration on the spring of the vehicle, and the drive. Either a torque detecting means for detecting the torque of the shaft or a rotational speed detecting means for detecting the rotational speed of the engine of the vehicle may be provided .

In still another embodiment of the present invention, the vibration detecting means further includes a bandpass filter circuit for extracting a specific frequency component, and detects the vibration component from the output of the bandpass filter circuit.

In yet another embodiment of the invention, the vibration detecting means further comprises a fast Fourier transform circuit to detect the vibration component from the output of the fast Fourier transform circuit.

In the present invention, the road surface is not determined by using the tire wheel speed and the tire front-rear force in contact with the road surface, which is considered to have a close causal relationship with the road surface μ, as in the prior art, but the engine is based on the difference in tire grip and slip. The road surface is determined by using the presence or absence of front-rear resonance vibration, and specifically, detection signals such as engine rotation speed, sprung front-rear acceleration, engine front-rear acceleration, and drive shaft torque are used. In the present invention, since the road surface is determined using the presence or absence of vibration, the influence of the gravity g component can be eliminated. Also, the presence or absence of vibration can be detected even if the vehicle speed is zero.

According to the present invention, the road surface condition can be determined with high accuracy without being affected by the road surface inclination and the speed.

It is a schematic diagram explaining the principle of an embodiment. It is a figure which shows the drive shaft torque on a high μ road and a low μ road, and the relationship between a slip ratio and a road surface μ. It is a simulation explanatory drawing of embodiment. It is a figure which shows the actual vehicle test result of Embodiment 1. It is a block diagram of the block of Embodiment 1. It is another block diagram of Embodiment 1. FIG. It is a processing flowchart of Embodiment 1. It is a figure which shows the actual vehicle test result of Embodiment 2. It is a block diagram of the structure of Embodiment 2. It is a processing flowchart of Embodiment 2. It is a figure which shows the actual vehicle test result of Embodiment 3. It is a block diagram of the block of Embodiment 3. It is a processing flowchart of Embodiment 3. It is a figure which shows the actual vehicle test result of Embodiment 4. It is a block diagram of the block of Embodiment 4. It is a processing flowchart of Embodiment 4.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Basic principle>
First, the basic principle of the embodiment will be described.

The road surface determination method in the embodiment detects the presence or absence of drive shaft (DS) vibration damping due to the difference in tire grip and slip at each part of the vehicle, and determines the road surface with reference to the applied throttle opening degree. An accelerometer is used as part of the vibration measurement as before, but it is not affected by gravitational acceleration because it focuses on the frequency of the alternating current component without referring to the direct current (DC) component. In addition, since the detected values can be obtained from the vehicle stopped state except for the transmission (T / M) rotation speed, the road surface can be determined at the time of starting from the vehicle stop.

When the drive torque is applied, the drive shaft (DS) twists and vibrates when the tires are gripped, while when the tires are slipped (road surface μ _max (maximum value of friction coefficient)), the drive shaft (DS) slips. The twist of the DS) spring is released and the twist vibration of the drive shaft (DS) disappears. When drive shaft (DS) torsional vibration occurs, the combined vibration of engine (E / G) block, engine (E / G) block front-rear resonance (E / G front-rear resonance) and drive shaft (DS) torsional resonance on the spring A mode appears, and when the drive shaft (DS) torsional vibration disappears, a simple vibration of engine (E / G) front-rear resonance appears. When the drive shaft (DS) torsional vibration occurs, the drive shaft (DS) torque has a torsional vibration, and the rotation speed of the engine (E / G) and transmission (T / M) is due to the drive shaft (DS) torque vibration. Fluctuations appear.

Therefore, by checking the vibration mode of each part based on the engine (E / G) block, spring front and rear, engine (E / G) or transmission (T / M) rotation speed, and drive shaft (DS) torque signal. , It is possible to indirectly know whether or not the tire is in the grip state, and the acceleration / deceleration torque (that is, throttle opening) at that time is compared with the torque reference value which is _{μ max (maximum value of friction coefficient μ) provided for each road surface.} Then, the current traveling road surface can be determined.

FIG. 1 shows the connection relationship between the engine (E / G) block 10, the transmission (T / M) 12 to the drive shaft (DS) 14 (power train (PT) system), the tire 16, the vehicle body 18, and the mount 20. It is a block diagram of the principle model.

In FIG. 1, a high μ road when the slip ratio − road surface μ characteristic, which is the relationship between the slip ratio of the tire 16 and the road surface μ characteristic, is set and the engine torque is applied in steps from the 0 Nm state. Measure the drive shaft (DS) torque, etc. in the case of (dry road (dry)) and low μ road (ice road (ice)).

FIG. 2 shows an example of the slip ratio-road surface μ characteristic and the drive shaft (DS) torque on the high μ road and the low μ road.

3 (a) to 3 (k) show the results of computer simulation given predetermined medium-sized vehicle specifications. In the figure, from the top, engine (E / G) torque, drive shaft (D / S) torque, vehicle speed, wheel speed, slip ratio, road surface μ, spring front-rear acceleration, engine (E / G) front-rear acceleration, engine ( E / G) Pitch angular acceleration, under-spring front-rear acceleration, and tire driving force are shown. The engine (E / G) block is shown as behavior with two degrees of freedom, front and back and pitch. The unsprung and engine (E / G) front-rear accelerations are shown as relative accelerations after the unsprung front-rear acceleration.

From FIG. 3, on a low μ road (on an ice road), the road surface μ _max is reached as shown in FIG. 3 (f) when the throttle is applied, so that the engine (E / G) block is shown in FIG. 3 (h). The front-rear acceleration is in a simple vibration state of front-rear resonance. In the figure, this simple vibration is shown as "E / G front-rear resonance period". The reason for the simple vibration state is that the twist of the drive shaft (DS) spring is released due to the tire slip, and the subsequent vibration from above the spring due to the drive shaft (DS) torsional vibration disappears.

On the other hand, on a high μ road (dry road), the drive shaft (DS) spring twist is maintained because the tire is in a grip state, and a drive shaft (DS) torsion resonance based on the upstream side of the drive shaft (DS) occurs, resulting in a spring. The top is vibrated. As a result, as shown in FIG. 3 (h), the front-rear acceleration of the engine (E / G) block has two frequencies of the drive shaft (DS) torsion frequency from the spring and the front-rear resonance of the engine (E / G). It becomes vibration.

Therefore, if the simple vibration state of the front-rear acceleration of the engine (E / G) block is detected and the acceleration / deceleration torque (throttle opening) at the time of detecting the simple vibration is compared with a predetermined torque reference value, the road surface can be discriminated. Normally, the resonance before and after the engine (E / G) block is around 10 Hz, so it is sufficient to pay attention to the vibration in this frequency range, and other low frequency components of DC (DC) to several Hz are removed by a bandpass filter or the like. It is possible to solve the problem of erroneous determination due to the conventional gravitational acceleration.

Here, in FIG. 3, a solid line is shown in the vertical direction between the engine (E / G) front-rear acceleration shown in FIG. 3 (h) and the spring-up front-back acceleration shown in FIG. It can be seen that the convex portion of the engine (E / G) front-rear acceleration when traveling on the road (ice road) and the concave portion (or concave and convex) of the front-rear acceleration on the spring coincide in time. This is because the engine (E / G) block and the spring are connected by the front and rear springs in the vehicle traveling direction, and as a result, both receive the acting force and the reaction force.

Therefore, instead of focusing on the engine (E / G) front-rear acceleration, focus on the sprung front-rear acceleration, and based on the bandpass filter processing value, determine whether the engine (E / G) front-rear resonance is simple vibration. It is also possible to judge the road surface by comparing the acceleration / deceleration torque (throttle opening) with the torque reference value (throttle reference value).

In addition, since the drive shaft (DS) torsional vibration continues on high μ roads (dry roads), the drive shaft (DS) torque is measured and the drive shaft (DS) corresponding to the transmission (T / M) gear ratio. It is also possible to determine whether or not the vibration has a torsion frequency, and compare the acceleration / deceleration torque (throttle opening) at the time of determination with the torque reference value (throttle reference value) to determine the road surface.

In addition, when the drive shaft (DS) torsional torque is generated, the counter torque is handled by the engine (E / G) block side, so the drive shaft is adjusted to the engine (E / G) rotation speed or transmission (T / M) rotation speed. (DS) Rotational speed fluctuates corresponding to torsional vibration. Therefore, it is also possible to determine whether the rotation speed includes the torsional vibration of the drive shaft (DS), and determine the road surface by referring to the acceleration / deceleration torque (throttle opening) at the time of determination as the torque reference value (throttle reference value). can.

The above is the basic principle of the embodiment, and next, the road surface determination of the embodiment will be described in more detail.

<Embodiment 1>
FIG. 4 shows the actual vehicle test results when the transmission (T / M) gear is chip-in accelerated from the coastal state on a high μ road and a low μ road with the low side gear setting. In the figure, the engine (E / G) torque estimated value, the sprung front-rear acceleration, and the engine (E / G) front-rear acceleration are shown from the top. The engine (E / G) front-rear acceleration shows the waveform as a result of bandpass filtering.

When traveling on a low μ road, the band path value of the engine (E / G) front-rear acceleration immediately after chip-in is in a simple vibration state of engine (E / G) front-rear resonance. It can be seen that the road surface can be determined by comparing the throttle opening with the throttle level value.

FIG. 5 shows a block diagram of the configuration of this embodiment. The devices include a transmission (T / M) gear set value detector 30, a throttle opening detector 32, an engine (E / G) front-rear acceleration detector 34, a bandpass filter circuit 36, and an engine (E / G) front-rear resonance frequency. It includes a storage circuit 38, a vibration frequency detection circuit 40, a throttle opening level determination circuit 42, a throttle opening storage circuit 44, an engine (E / G) front-rear resonance frequency matching circuit 46, and a road surface determination circuit 48.

The transmission (T / M) gear set value detector 30 detects the gear stage of the transmission (T / M) and outputs it to the road surface determination circuit 48.

The throttle opening degree detector 32 detects the throttle opening degree as acceleration / deceleration torque and outputs it to the vibration frequency detection circuit 40 and the throttle opening degree level determination circuit 42.

The engine (E / G) front-rear acceleration detector 34 detects the engine (E / G) front-rear acceleration and outputs it to the bandpass filter circuit 36.

As described above, the bandpass filter circuit 36 extracts a signal of a specific frequency (near 10 Hz) from the front-rear acceleration of the engine (E / G), removes other frequency components as noise, and removes the other frequency components as noise, and the vibration frequency detection circuit 40. Output to.

The vibration frequency detection circuit 40 detects the vibration frequency when the throttle opening changes based on the throttle opening detection signal from the throttle opening detector 32 and the output signal of the bandpass filter circuit 36, and detects the vibration frequency of the engine (E / G) Output to the front-rear resonance frequency matching circuit 46.

The engine (E / G) front-rear resonance frequency storage circuit 38 stores the engine (E / G) front-rear resonance value in advance.

The front-rear (E / G) front-rear resonance frequency matching circuit 46 of the engine is detected by the front-rear resonance frequency of the engine (E / G) stored in the front-rear resonance frequency storage circuit 38 of the engine (E / G) and the vibration frequency detection circuit 40. By collating with the vibration frequency, it is determined whether or not the two are almost the same.

The throttle opening level determination circuit 42 compares the detected throttle opening with the throttle opening (throttle reference value) stored in the throttle opening storage circuit 44, which is μmax of each road surface, and compares the result. It is output to the road surface determination circuit 48.

The road surface determination circuit 48 includes the gear stage detected by the transmission (T / M) gear set value detector 30, the collation result of the engine (E / G) front-rear resonance frequency collation circuit 46, and the throttle opening level determination circuit 42. Based on the judgment result of, the road surface is judged and output. That is, in consideration of the detected transmission (T / M) gear stage, the judgment result of the throttle opening when the detected vibration frequency almost matches the front-rear resonance frequency of the engine (E / G) is output as the road surface judgment result. do.

Depending on the transmission (T / M) gear stage, the drive shaft (DS) torsional resonance frequency approaches the engine (E / G) front-rear resonance frequency, making it difficult to determine the road surface by detecting the engine (E / G) front-rear resonance frequency. (If engine (E / G) front-rear vibrations of similar frequencies occur on the high μ road and low μ road, it may be difficult to distinguish between them), but in consideration of the gear stage, the drive shaft (DS) The accuracy of road surface determination can be ensured by not performing road surface determination at a specific gear stage where the torsional resonance frequency approaches the engine (E / G) front-rear resonance frequency.

Specifically, the engine (E / G) front-rear acceleration detector 34 is composed of an acceleration sensor, and includes a bandpass filter circuit 36, an engine (E / G) front-rear resonance frequency storage circuit 38, a vibration frequency detection circuit 40, and a throttle open. The degree level determination circuit 42, the throttle opening storage circuit 44, the engine (E / G) front-rear resonance frequency matching circuit 46, and the road surface determination circuit 48 are composed of an ECU (electronic control circuit) including one or more processors and memories. Will be done. The processor functions as a vibration frequency detection circuit 40, a road surface determination circuit 48, and the like by executing a processing program stored in a ROM or the like. The memory stores the front-rear resonance frequency of the engine (E / G) and the throttle opening degree which is μmax of each road surface, and functions as the engine (E / G) front-rear resonance frequency storage circuit 38 and the throttle opening degree storage circuit 44.

In the configuration block diagram of FIG. 5, the bandpass filter circuit 36 and the vibration frequency detection circuit 40 are combined to detect the vibration frequency of the engine (E / G) front-rear acceleration when the throttle opening is changed. The vibration frequency may be detected using (FFT).

FIG. 6 shows a block diagram of the configuration in this case. Instead of the bandpass filter circuit 36, the vibration frequency detection circuit 40, and the engine (E / G) front-rear resonance frequency matching circuit 46 in FIG. 5, the FFT circuit 50 and the engine (E / G) front-rear resonance frequency gain reading circuit 52 are used. Be prepared.

The FFT circuit 50 performs a fast Fourier transform (FFT) on the detected engine (E / G) front-rear acceleration signal at the timing when the throttle opening changes, and outputs the detected engine (E / G) front-rear resonance frequency to the gain reading circuit 52. do.

The engine (E / G) front-rear resonance frequency gain reading circuit 52 reads the FFT gain at the resonance frequency stored in the engine (E / G) front-rear resonance frequency storage circuit 38, and when this exceeds a predetermined threshold value. The gain is output to the road surface determination circuit 48.

The road surface determination circuit 48 determines the road surface using the determination result from the gain reading circuit 52 of the front-rear resonance frequency of the engine (E / G) and outputs the result.

FIG. 7 shows a processing flowchart of the present embodiment. It is a processing flowchart which is executed in the constituent block shown in FIG.

First, an initial value for determining the road surface is set (S101). That is, the front-rear resonance value of the engine (E / G), the drive shaft (DS) torsional resonance frequency reference table for the transmission (T / M) gear stage, the bandpass filter constant, etc. are set.

Next, the transmission (T / M) gear set value detector 30 detects the gear stage (gear position) (S102). The detected gear stage is supplied to the road surface determination circuit 48.

The road surface determination circuit 48 reads the drive shaft (DS) torsional resonance frequency corresponding to the detected gear stage from the reference table (S103), and reads out the drive shaft (DS) torsional resonance frequency and the engine set as an initial value (S103). E / G) It is determined whether or not the front-rear resonance values are substantially equal (S104). When both are substantially equal, the processing after S102 is repeated without performing the road surface determination, and when both are not approximately equal, the process proceeds to the next processing. As described above, this determination process prevents the road surface determination from being performed in a specific gear stage where the drive shaft (DS) torsional resonance frequency approaches the engine (E / G) front-rear resonance frequency. ..

When both are not approximately equal (NO in S104), the throttle opening detector 32 detects the throttle opening (S105), and the engine (E / G) front-rear acceleration detector 34 detects the engine (E / G) front-rear acceleration. Detect (S106). The bandpass filter circuit 36 performs bandpass filtering on the detected engine (E / G) front-rear acceleration (S107).

Next, the vibration frequency detection circuit 40 determines whether or not the throttle opening has changed (S108), and when the throttle opening has changed (YES in S108), the bandpass filtered engine (E / G) The vibration frequency is detected from the front-rear acceleration signal (S109).

Next, the engine (E / G) front-rear resonance frequency matching circuit 46 determines whether or not the detected vibration frequency substantially matches the engine (E / G) front-rear resonance value set as the initial value ( S110). When the detected signal frequency substantially matches the front-rear resonance frequency of the engine (E / G) (YES in S110), the throttle opening level determination circuit 42 determines the throttle opening level (S111) and determines the road surface. (S112). That is, the throttle opening degree is compared with the throttle opening degree which is μmax of each road surface stored in the throttle opening degree storage circuit 44, and the corresponding road surface is determined and output.

<Embodiment 2>
FIG. 8 shows the actual vehicle test results in this embodiment. In the figure, the engine (E / G) torque estimated value, the engine (E / G) front-rear acceleration signal bandpass-filtered signal, and the sprung front-rear acceleration signal bandpass-filtered are shown from the top. The road surface can be determined by utilizing the fact that the bandpass filter processing value of the spring acceleration corresponds to the simple vibration state of the front-rear resonance of the engine (E / G).

FIG. 9 shows a block diagram of the configuration of this embodiment. The devices include a transmission (T / M) gear set value detector 30, a throttle opening detector 32, a sprung front-rear acceleration detector 35, a bandpass filter circuit 36, an engine (E / G) front-rear resonance frequency storage circuit 38, and the like. It includes a vibration frequency detection circuit 40, a throttle opening level determination circuit 42, a throttle opening storage circuit 44, an engine (E / G) front-rear resonance frequency matching circuit 46, and a road surface determination circuit 48. The difference from FIG. 5 is that the sprung front-rear acceleration detector 35 is provided instead of the engine (E / G) front-rear acceleration detector 34.

The transmission (T / M) gear set value detector 30 detects the gear stage of the transmission (T / M) and outputs it to the road surface determination circuit 48.

The throttle opening degree detector 32 detects the throttle opening degree and outputs it to the vibration frequency detection circuit 40 and the throttle opening degree level determination circuit 42.

The sprung front-rear acceleration detector 35 detects the sprung front-rear acceleration and outputs it to the bandpass filter circuit 36.

The bandpass filter circuit 36 extracts a signal of a specific frequency (near 10 Hz) from the longitudinal acceleration on the spring, removes other frequency components as noise, and outputs the signal to the vibration frequency detection circuit 40.

The vibration frequency detection circuit 40 detects the vibration frequency when the throttle opening changes based on the throttle opening detection signal from the throttle opening detector 32 and the output signal of the bandpass filter circuit 36, and detects the vibration frequency of the engine (E / G) Output to the front-rear resonance frequency matching circuit 46.

The engine (E / G) front-rear resonance frequency storage circuit 38 stores the engine (E / G) front-rear resonance value in advance.

The front-rear (E / G) front-rear resonance frequency matching circuit 46 of the engine is detected by the front-rear resonance frequency of the engine (E / G) stored in the front-rear resonance frequency storage circuit 38 of the engine (E / G) and the vibration frequency detection circuit 40. By collating with the vibration frequency, it is determined whether or not the two are almost the same.

The throttle opening level determination circuit 42 compares the detected throttle opening degree with the throttle opening degree stored in the throttle opening degree storage circuit 44, which is μmax of each road surface, and outputs the result to the road surface determination circuit 48. Output.

The road surface determination circuit 48 includes the gear stage detected by the transmission (T / M) gear set value detector 30, the collation result of the engine (E / G) front-rear resonance frequency collation circuit 46, and the throttle opening level determination circuit 42. Based on the judgment result of, the road surface is judged and output. That is, in consideration of the detected transmission (T / M) gear stage, the judgment result of the throttle opening when the detected vibration frequency almost matches the front-rear resonance frequency of the engine (E / G) is output as the road surface judgment result. do.

FIG. 10 shows a processing flowchart of the present embodiment.

First, an initial value for determining the road surface is set (S201). That is, the front-rear resonance value of the engine (E / G), the drive shaft (DS) torsional resonance frequency reference table for the transmission (T / M) gear stage, the bandpass filter constant, etc. are set.

Next, the transmission (T / M) gear set value detector 30 detects the gear stage (gear position) (S202). The detected gear stage is supplied to the road surface determination circuit 48.

The road surface determination circuit 48 reads the drive shaft (DS) torsional resonance frequency corresponding to the detected gear stage from the reference table (S203), and reads out the drive shaft (DS) torsional resonance frequency and the engine set as an initial value (S203). E / G) It is determined whether or not the front-rear resonance values are substantially equal (S204). When both are substantially equal, the processing after S202 is repeated without performing the road surface determination, and when both are not approximately equal, the process proceeds to the next processing. This determination process prevents the road surface determination from being performed at a specific gear stage where the drive shaft (DS) torsional resonance frequency approaches the engine (E / G) front-rear resonance frequency.

When both are not substantially equal (NO in S204), the throttle opening degree detector 32 detects the throttle opening degree (S205), and the spring front-rear acceleration detector 35 detects the front-back acceleration on the spring (S206). The bandpass filter circuit 36 performs bandpass filtering on the detected longitudinal acceleration on the spring (S207).

Next, the vibration frequency detection circuit 40 determines whether or not the throttle opening has changed (S208), and when the throttle opening has changed (YES in S208), the bandpass-filtered longitudinal acceleration on the spring. The vibration frequency is detected from the signal (S209).

Next, the engine (E / G) front-rear resonance frequency matching circuit 46 determines whether or not the detected vibration frequency substantially matches the engine (E / G) front-rear resonance value set as the initial value ( S210). When the detected signal frequency substantially matches the front-rear resonance frequency of the engine (E / G) (YES in S210), the throttle opening level determination circuit 42 determines the throttle opening level (S211) and determines the road surface. (S212). That is, the throttle opening degree is compared with the throttle opening degree which is μmax of each road surface stored in the throttle opening degree storage circuit 44, and the corresponding road surface is determined and output.

<Embodiment 3>
FIG. 11 shows the actual vehicle test results in this embodiment. In the figure, the engine (E / G) torque and the drive shaft (DS) torque are shown from the top. The drive shaft (DS) torque measurement value on the high μ road shows the vibration waveform of the drive shaft (DS) torsional resonance determined by the transmission (T / M) gear, and does not appear on the low μ road. The road surface can be determined by detecting the presence or absence of torsional resonance and comparing the throttle opening at the time of detection with the throttle level value.

When detecting the vibration of the drive shaft (DS) torsional resonance, the noise may be removed by using the bandpass filter processing value of the drive shaft (DS) torque of several Hz to several tens Hz.

FIG. 12 shows a block diagram of the configuration of this embodiment. The devices include a transmission (T / M) gear set value detector 30, a throttle opening detector 32, a drive shaft (DS) torque detector 33, a drive shaft (DS) torsional resonance frequency storage circuit 39, and a vibration frequency detection circuit 40. A throttle opening level determination circuit 42, a throttle opening storage circuit 44, a drive shaft (DS) torsional resonance frequency matching circuit 47, and a road surface determination circuit 48 are provided.

The transmission (T / M) gear set value detector 30 detects the gear stage of the transmission (T / M) and outputs it to the road surface determination circuit 48.

The throttle opening degree detector 32 detects the throttle opening degree and outputs it to the vibration frequency detection circuit 40 and the throttle opening degree level determination circuit 42.

The drive shaft (DS) torque detector 33 detects the torque of the drive shaft (DS) and outputs it to the vibration frequency detection circuit 40.

The vibration frequency detection circuit 40 detects the vibration frequency when the throttle opening changes, based on the throttle opening detection signal from the throttle opening detector 32 and the output signal of the drive shaft (DS) torque detector 33. The drive shaft (DS) is output to the torsional resonance frequency matching circuit 47.

The drive shaft (DS) torsional resonance frequency storage circuit 39 stores in advance the torsional resonance value of the drive shaft (DS) for each gear stage.

The drive shaft (DS) torsional resonance frequency matching circuit 47 detects the drive shaft (DS) torsional resonance frequency and the vibration frequency stored in the drive shaft (DS) torsional resonance frequency storage circuit 39 corresponding to the detected gear stage. The vibration frequencies detected by the circuit 40 are collated, and it is determined whether or not the two are substantially the same.

The throttle opening level determination circuit 42 compares the detected throttle opening degree with the throttle opening degree stored in the throttle opening degree storage circuit 44, which is μmax of each road surface, and outputs the result to the road surface determination circuit 48. Output.

The road surface determination circuit 48 determines and outputs the road surface based on the collation result of the drive shaft (DS) torsional resonance frequency collation circuit 47 and the determination result of the throttle opening level determination circuit 42. That is, the determination result of the throttle opening when the detected vibration frequency substantially matches the drive shaft (DS) torsional resonance frequency is output as the road surface determination result.

Specifically, the drive shaft (DS) torque detector 33 is composed of a torque sensor, and is composed of a drive shaft (DS) torsional resonance frequency storage circuit 39, a vibration frequency detection circuit 40, a throttle opening level determination circuit 42, and a throttle opening. The storage circuit 44, the drive shaft (DS) torsional resonance frequency matching circuit 47, and the road surface determination circuit 48 are composed of an ECU (electronic control circuit) including one or more processors and a memory. The processor functions as a vibration frequency detection circuit 40, a road surface determination circuit 48, and the like by executing a processing program stored in a ROM or the like. The memory stores the drive shaft (DS) torsional resonance frequency and the throttle opening degree which is μmax of each road surface, and functions as the drive shaft (DS) torsional resonance frequency storage circuit 39 and the throttle opening degree storage circuit 44.

As described above, a bandpass filter circuit may be further provided between the drive shaft (DS) torque detector 33 and the vibration frequency detection circuit 40.

FIG. 13 shows a processing flowchart of the present embodiment.

First, an initial value for determining the road surface is set (S301). That is, the drive shaft (DS) torsional resonance frequency reference table, bandpass filter constant, etc. for the transmission (T / M) gear stage are set.

Next, the transmission (T / M) gear set value detector 30 detects the gear position (S302), and the throttle opening degree detector 32 detects the throttle opening degree (S303).

Further, the drive shaft (DS) torque detector 33 detects the drive shaft (DS) torque (S304), the bandpass filter circuit performs bandpass filtering processing (S305), and the drive shaft (DS) torque is output to the vibration frequency detection circuit 40.

The vibration frequency detection circuit 40 determines whether or not the throttle opening has changed based on the detection signal from the throttle opening detector 32 (S306), and when the throttle opening changes, the drive shaft (DS) torque. The vibration frequency is detected from the signal (S307).

Next, the drive shaft (DS) torsional resonance frequency matching circuit 47 determines whether or not the torsional frequency from the drive shaft (DS) torsional resonance frequency storage circuit 39 and the detected vibration frequency substantially match (S308). ), The determination result is output to the road surface determination circuit 48.

On the other hand, the throttle opening level determination circuit 42 compares the detected throttle opening with the throttle opening stored in the throttle opening storage circuit 44, which is μmax of each road surface, and determines the result as a road surface determination circuit. Output to 48 (S309).

The road surface determination circuit 48 determines the road surface using the determination result in the throttle opening level determination circuit 42 when the drive shaft (DS) torsional resonance frequency matching circuit 47 determines that they match (S310).

<Embodiment 4>
FIG. 14 shows the actual vehicle test results of this embodiment. In the figure, the engine (E / G) torque, the drive shaft (DS) torque, and the engine (E / G) rotation speed are shown from the top. The engine (E / G) rotation speed shows the result of applying a bandpass filter of several Hz to several tens of Hz. As shown in this figure, the engine (E / G) rotation speed has a component with the same period as the high μ road drive shaft (DS) torsional vibration.

Therefore, the drive shaft (DS) torsional vibration can be detected based on the engine (E / G) rotation speed bandpass filter processing value, and the throttle opening at the time of detection can be compared with the throttle level value to determine the road surface. The transmission (T / M) rotation speed may be used instead of the engine (E / G) rotation speed.

In FIG. 14, there is a phase shift in the bandpass filter value of the engine (E / G) rotation speed with respect to the drive shaft (DS) torque waveform, and the drive shaft (DS) torque is delayed by 270 ° from the time when it reaches the convex peak. At that point, the engine (E / G) rotation speed has reached a convex peak. This is because the drive shaft (DS) torque is a load torque on the engine (E / G) rotational inertia side, so there is a 180 ° delay, and the engine (E / G) rotational speed is the engine (E / G) angular acceleration. As a result of the delay of 90 ° in the first-order integration, the delay is 270 ° in total.

FIG. 15 shows a block diagram of the configuration of this embodiment. The devices include a transmission (T / M) gear set value detector 30, a throttle opening detector 32, an engine (E / G) rotation speed detector 31, a bandpass filter circuit 36, and a drive shaft (DS) torsional resonance frequency memory. A circuit 39, a vibration frequency detection circuit 40, a throttle opening level determination circuit 42, a throttle opening storage circuit 44, a drive shaft (DS) torsional resonance frequency matching circuit 47, and a road surface determination circuit 48 are provided.

The transmission (T / M) gear set value detector 30 detects the gear stage of the transmission (T / M) and outputs it to the road surface determination circuit 48.

The throttle opening degree detector 32 detects the throttle opening degree and outputs it to the vibration frequency detection circuit 40 and the throttle opening degree level determination circuit 42.

The engine (E / G) rotation speed detector 31 detects the rotation speed of the engine (E / G) and outputs it to the bandpass filter circuit 36.

The bandpass filter circuit 36 extracts a specific frequency component from the rotation speed signal of the engine (E / G) and outputs it to the vibration frequency detection circuit 40.

The vibration frequency detection circuit 40 detects the vibration frequency when the throttle opening changes based on the throttle opening detection signal from the throttle opening detector 32 and the output signal of the bandpass filter circuit 36, and detects the vibration frequency of the drive shaft (DS). ) Output to the torsional resonance frequency matching circuit 47.

The drive shaft (DS) torsional resonance frequency storage circuit 39 stores in advance the torsional resonance value of the drive shaft (DS) for each gear stage.

The drive shaft (DS) torsional resonance frequency matching circuit 47 detects the drive shaft (DS) torsional resonance frequency and the vibration frequency stored in the drive shaft (DS) torsional resonance frequency storage circuit 39 corresponding to the detected gear stage. The vibration frequencies detected by the circuit 40 are collated, and it is determined whether or not the two are substantially the same.

The throttle opening level determination circuit 42 compares the detected throttle opening degree with the throttle opening degree stored in the throttle opening degree storage circuit 44, which is μmax of each road surface, and outputs the result to the road surface determination circuit 48. Output.

The road surface determination circuit 48 determines and outputs the road surface based on the collation result of the drive shaft (DS) torsional resonance frequency collation circuit 47 and the determination result of the throttle opening level determination circuit 42. That is, the determination result of the throttle opening when the detected vibration frequency substantially matches the drive shaft (DS) torsional resonance frequency is output as the road surface determination result.

FIG. 16 shows a processing flowchart of the present embodiment.

First, an initial value for determining the road surface is set (S401). That is, the drive shaft (DS) torsional resonance frequency reference table, bandpass filter constant, etc. for the transmission (T / M) gear stage are set.

Next, the transmission (T / M) gear set value detector 30 detects the gear position (S402), and the throttle opening degree detector 32 detects the throttle opening degree (S403).

Further, the engine (E / G) rotation speed detector 31 detects the engine (E / G) rotation speed (S404), the bandpass filter circuit 36 performs bandpass filtering processing (S405), and the vibration frequency detection circuit 40 Output to.

The vibration frequency detection circuit 40 determines whether or not the throttle opening has changed based on the detection signal from the throttle opening detector 32 (S406), and when the throttle opening changes, the bandpass filter processing value is used. The vibration frequency is detected (S407).

Next, the drive shaft (DS) torsional resonance frequency matching circuit 47 determines whether or not the torsional frequency from the drive shaft (DS) torsional resonance frequency storage circuit 39 and the detected vibration frequency substantially match (S408). ), The determination result is output to the road surface determination circuit 48.

On the other hand, the throttle opening level determination circuit 42 compares the detected throttle opening with the throttle opening stored in the throttle opening storage circuit 44, which is μmax of each road surface, and determines the result as a road surface determination circuit. Output to 48 (S409).

The road surface determination circuit 48 determines the road surface using the determination result in the throttle opening level determination circuit 42 when the drive shaft (DS) torsional resonance frequency matching circuit 47 determines that they match (S410).

As described above, in the first embodiment, the road surface can be determined by using the front-rear acceleration of the engine (E / G), in the second embodiment, the road surface can be determined by using the front-rear acceleration on the spring, and in the third embodiment, the drive surface can be determined. Since the road surface can be determined using the shaft (DS) torque and the road surface can be determined using the engine (E / G) rotation speed or the transmission (T / M) rotation speed in the fourth embodiment, the gravity g component can be determined. The road surface can be judged by removing the influence of. Further, since physical quantities other than the transmission (T / M) rotation speed can be obtained even when the vehicle is stopped, the road surface can be determined even when the vehicle is stopped and started.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications are possible.

For example, in addition to using any one of the first to fourth embodiments alone to perform the road surface determination, two or more of the first to fourth embodiments may be combined to perform the road surface determination in a complex manner. .. For example, it is a combination of the first embodiment and the fourth embodiment.

Further, also in the second to fourth embodiments, the vibration frequency may be detected by using the FFT circuit instead of the bandpass filter circuit as in the first embodiment.

Further, in the first embodiment, the engine (E / G) front-rear resonance frequency storage circuit 38 to the road surface determination circuit 48 are composed of one or a plurality of processors and an ECU including a memory, but at least one of these constituent blocks. May be implemented as a dedicated hardware circuit (ASIC, FPGA, etc.).

Further, in the present embodiment, the power train (PT) has been described as an engine (E / G) and a transmission (T / M), but it is assumed that the engine (E / G) includes a motor, and the engine (motor). Included) and transmission (T / M). When the vehicle is equipped with only a motor, the engine (E / G) may be read as a motor and applied.

10 engine (E / G) block, 12 power train (PT), 14 drive shaft (DS), 16 tires, 18 car body, 20 mounts, 30 transmission (T / M) gear setting detector, 32 throttle opening detection Instrument, 34 engine (E / G) front-rear acceleration detector, 36 bandpass filter circuit, 38 engine (E / G) front-rear resonance frequency storage circuit, 40 vibration frequency detection circuit, 42 throttle opening level determination circuit, 44 throttle open Throttle memory circuit, 46 engine (E / G) front-rear resonance frequency matching circuit, 48 road surface judgment circuit.

Claims (8)

Vibration detecting means for detecting the vibration component of the front-rear resonance of the vehicle engine,
A detection means for detecting the acceleration / deceleration torque of the engine of the vehicle and
With the coefficient of friction of the road surface as μ, the tire grip state of the vehicle shifts to the tire slip state on the high μ road including the dry road and the low μ road including the ice road, which are obtained in advance under predetermined vehicle specifications. A storage means for storing the torque reference value corresponding to the maximum value μ _max of μ, and
A gear stage detecting means for detecting the current transmission gear stage of the vehicle, and
A frequency storage means for storing the front-rear resonance frequency of the vehicle and
A collation means for collating the vibration component with the front-rear resonance frequency of the engine,
Comparing the acceleration / deceleration torque at the time when the vibration component and the front-rear resonance frequency of the engine match with the torque reference value, the road surface on which the vehicle is traveling is the high μ road or the low μ road. Judgment means to determine the existence and
Wherein the determining means reads from the reference table to the drive shaft torsional resonance frequency corresponding to the detected transmission gear, the read drive shaft torsional pre SL-size constant in the case the resonance frequency is equal to the engine longitudinal resonance frequency A road surface judgment device that does not execute. Detection means for detecting the throttle opening of the vehicle and
Vibration detecting means for detecting the vibration component of the front-rear resonance of the engine of the vehicle at the time when the throttle opening changes.
With the coefficient of friction of the road surface as μ, the tire grip state of the vehicle shifts to the tire slip state on the high μ road including the dry road and the low μ road including the ice road, which are obtained in advance under predetermined vehicle specifications. A storage means for storing the accelerator opening reference value corresponding to the maximum value μ _{max of μ, and}
A gear stage detecting means for detecting the current transmission gear stage of the vehicle, and
A frequency storage means for storing the front-rear resonance frequency of the vehicle and
A collation means for collating the vibration component with the front-rear resonance frequency of the engine,
Comparing the throttle opening at the time when the vibration component and the front-rear resonance frequency of the engine match with the throttle opening reference value, whether the road surface on which the vehicle is traveling is the high μ road or the low μ. Judgment means to judge whether it is a road and
The determination means reads the drive shaft torsional resonance frequency corresponding to the detected transmission gear stage from the reference table, and executes the determination when the read drive shaft torsional resonance frequency is equal to the engine front-rear resonance frequency. No, road surface judgment device. The vibration detecting means is
Engine front-rear acceleration detecting means for detecting the front-rear acceleration of the engine of the vehicle
The vibration component is detected from the detected front-rear acceleration of the engine.
The road surface determination device according to any one of claims 1 and 2. The vibration detecting means is
The road surface determination device according to any one of claims 1 and 2, further comprising a sprung front-rear acceleration detecting means for detecting the front-rear acceleration on the spring of the vehicle, and detecting the vibration component from the detected front-rear acceleration on the spring. .. The vibration detecting means is
Torque detecting means for detecting the torque of the drive shaft
The vibration component is detected from the detected torque.
The road surface determination device according to any one of claims 1 and 2. The vibration detecting means is
Rotational speed detecting means for detecting the rotational speed of the engine of the vehicle
The vibration component is detected from the detected rotation speed of the engine.
The road surface determination device according to any one of claims 1 and 2. The vibration detecting means further
Bandpass filter circuit that extracts specific frequency components
The road surface determination device according to any one of claims 1 to 6, wherein the vibration component is detected from the output of the bandpass filter circuit. The vibration detecting means further
Fast Fourier transform circuit
The road surface determination device according to any one of claims 1 to 6, wherein the vibration component is detected from the output of the fast Fourier transform circuit.

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