JP2016215736A - Road gradient estimation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate the gradient of a road a vehicle travels on.SOLUTION: An estimation apparatus includes: a vehicular speed sensor 21 for detecting a vehicular speed; an acceleration sensor 24 for detecting acceleration in forward and reverse directions; a yaw rate sensor 25 for detecting a value for determining whether or not a vehicle is turning; an acceleration calculation part 511 for calculating acceleration in forward and reverse directions on the basis of the vehicular speed detected by the vehicular speed sensor 21; a low-pass filter 512 for applying, and output, filtering processing to respectively the acceleration detected by the acceleration sensor 24 and the acceleration calculated by the acceleration calculation part 511 for eliminating noise components; a road gradient estimation part 513 for estimating a gradient of a road on which a vehicle is traveling on the basis of the output value of the low-pass filter 512; an in-turning determination part 515 for determining whether or not the vehicle is turning on the basis of the detection value of the yaw rate sensor 25; and a filter characteristic change part 514 for changing a characteristic of the filtering processing on the basis of the determination result of the in-turning determination part 515.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a road surface gradient estimation device.

  2. Description of the Related Art Conventionally, there is known a road surface gradient estimation device that estimates the gradient of a road surface on which a vehicle travels based on a detected acceleration detected by an acceleration sensor and a calculated acceleration calculated based on a vehicle speed detected by a vehicle speed sensor. Yes.

  In the road surface gradient estimation device, noise caused by vehicle posture changes (such as squats, dives, and turns), shift shocks, vehicle vibrations due to road surface irregularities, and the like is superimposed on the detected acceleration. The calculated acceleration is calculated by differentiating the detected vehicle speed, and a high-frequency noise component superimposed on the vehicle speed at the time of calculation is amplified. These noises cause a decrease in the estimation accuracy of the road surface gradient. Thus, a technique is disclosed in which a filtering process using a low-pass filter is performed on the detected acceleration and the calculated acceleration in order to remove a noise component superimposed on the detected acceleration and the calculated acceleration (see, for example, Patent Document 1).

JP 2013-184673 A

  However, in the filter processing for the detected acceleration and the calculated acceleration, if the time constant is increased to increase the filter effect, that is, the noise removal effect, the delay due to the filter processing increases and the road surface gradient estimation process (hereinafter referred to as “road surface gradient estimation process”). )) Becomes worse. As a result, the estimation accuracy of the road surface gradient decreases.

  On the other hand, if the time constant is reduced to increase the responsiveness of the road gradient estimation process, the noise removal effect in the filter process is weakened, and the estimation accuracy of the road gradient is lowered due to the influence of noise. Therefore, in order to increase the estimation accuracy of the road surface gradient, it is required to determine the characteristics of the filter processing in consideration of both the noise removal effect and the responsiveness of the road surface gradient estimation processing.

  The road surface gradient estimation device disclosed in Patent Document 1 changes the characteristics of filter processing using a low-pass filter for detected acceleration and calculated acceleration in accordance with the vehicle speed. Specifically, when the vehicle speed is high, this road surface gradient estimation device weakens the noise removal effect in the filter processing and increases the responsiveness of the road surface gradient estimation processing. Thereby, the followability to the gradient change when the change rate of the road surface gradient is large can be improved. However, in this road surface gradient estimation device, when a change in the posture of the vehicle occurs when the vehicle speed is high, there is a risk that the estimation accuracy of the road surface gradient is lowered due to the strong influence of noise.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a road surface gradient estimation device that can accurately estimate the gradient of a road surface on which a vehicle travels.

  In order to achieve the above object, a road surface gradient estimation apparatus according to an aspect of the present invention includes a first detection unit that detects a vehicle speed of a vehicle, and a second detection unit that detects an acceleration in the front-rear direction of the vehicle. And a third detection means for detecting a value for determining whether or not the vehicle is turning, and a longitudinal acceleration of the vehicle is calculated based on a vehicle speed detected by the first detection means. A filter means for performing a filter process for removing a noise component on each of the acceleration detected by the calculation means, the acceleration detected by the second detection means, and the acceleration calculated by the calculation means; and the filter A determination unit that estimates a slope of a road surface on which the vehicle travels based on an output value of the unit, and a determination that determines whether the vehicle is turning based on a detection value of the third detection unit Means, Based on the determination result of the serial determination means, and changing means for changing the characteristics of the filtering process.

  In the road surface gradient estimation device, the changing unit may increase a time constant in the filtering process when a determination result of the determining unit is affirmative.

  The road surface gradient estimation apparatus may further include an acquisition unit that acquires an angular velocity of the vehicle turning, and the change unit may determine a time constant after the change based on the angular velocity acquired by the acquisition unit. .

  According to the road surface gradient estimation apparatus of the present invention, it is possible to accurately estimate the gradient of the road surface on which the vehicle travels.

1 is a schematic overall configuration diagram showing a vehicle on which a road surface gradient estimation device according to an embodiment of the present invention is mounted. It is a functional block diagram which shows the electronic control unit and related structure which concern on one Embodiment of this invention. It is a functional block diagram which shows the structure of the road surface gradient estimation apparatus which concerns on one Embodiment of this invention. It is a flowchart of the filter characteristic change process which concerns on one Embodiment of this invention.

  Hereinafter, a road surface gradient estimation apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a schematic overall configuration diagram showing a vehicle on which a road surface gradient estimation apparatus according to an embodiment of the present invention is mounted.

  The vehicle 1 includes an engine 10, a clutch 11, a transmission 12, a propeller shaft 13, a differential device 14, a drive shaft 15, left and right rear wheels (drive wheels) 16L and 16R, left and right front wheels 17L and 17R, an engine speed sensor 20, Vehicle speed sensor 21 (first detection means), accelerator pedal sensor 22, brake switch 23, acceleration sensor 24 (second detection means), yaw rate sensor 25 (third detection means, acquisition means), accelerator pedal 31, brake A pedal 32 and an electronic control unit (hereinafter referred to as “ECU”) 50 are provided.

  The output shaft of the engine 10 is connected to the input shaft of the transmission 12 via the clutch 11. The output shaft of the transmission 12 is connected to each of the left and right rear wheels 16L, 16R via a propeller shaft 13, a differential device 14, and a drive shaft 15.

  The clutch 11 connects and disconnects a power transmission path between the output shaft of the engine 10 and the input shaft of the transmission 12. The transmission 12 is, for example, an automatically controlled manual transmission (AMT).

  The engine rotation speed sensor 20 detects the rotation speed (engine rotation speed) of a crankshaft (not shown) of the engine 10. The vehicle speed sensor 21 detects the traveling speed (vehicle speed) of the vehicle 1 from the rotational speed of the propeller shaft 13, the output shaft, or the wheels. The accelerator pedal sensor 22 detects the accelerator opening from the depression amount of the accelerator pedal 31. The brake switch 23 detects whether or not the brake pedal 32 is depressed. The brake switch 23 outputs an on signal when the brake pedal is depressed, for example. The acceleration sensor 24 detects the acceleration in the front-rear direction of the vehicle 1 based on the force applied to itself. The acceleration sensor 24 is, for example, a pendulum type or strain gauge type acceleration sensor. The yaw rate sensor 25 detects the angular velocity of the turning of the vehicle 1 (hereinafter referred to as “turning angular velocity”). The sensor values of these various sensors 20 to 25 are transmitted to the electrically connected ECU 50.

  The ECU 50 performs various controls of the engine 10, the clutch 11, the transmission 12, and the like, and includes a known CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), input port, output port, and the like. Is provided.

  FIG. 2 is a functional block diagram showing an electronic control unit and related configurations according to an embodiment of the present invention.

  The ECU 50 includes a road surface gradient estimation processing unit 51 and a travel control unit 52 as some functional elements. In the present embodiment, these functional elements are described as being included in the ECU 50, which is an integral piece of hardware. However, any one of these functional elements may be provided in separate hardware.

  The road surface gradient estimation processing unit 51 estimates the gradient of the road surface on which the vehicle 1 travels based on the detected acceleration and the calculated acceleration. Here, the detected acceleration is an acceleration in the front-rear direction of the vehicle 1 detected by the acceleration sensor 24. The detected acceleration includes an acceleration component due to a change in vehicle speed and a gravitational acceleration component applied to the vehicle 1 when the road surface on which the vehicle 1 travels is inclined. The calculated acceleration is an acceleration in the front-rear direction of the vehicle 1 calculated based on the vehicle speed detected by the vehicle speed sensor 21. The calculated acceleration includes only an acceleration component due to a change in vehicle speed. The road surface gradient estimation processing unit 51 estimates the road surface gradient based on the gravitational acceleration component obtained from the difference between the detected acceleration and the calculated acceleration.

  The value of the road surface gradient estimated by the road surface gradient estimation processing unit 51 (hereinafter referred to as “gradient estimated value”) is input to the travel control unit 52, for example. Details of the road gradient estimation processing unit 51 will be described later with reference to FIG.

  The traveling control unit 52 controls the engine 10, the clutch 11, and the transmission 12 based on the input sensor value and the estimated gradient value. For example, the traveling control unit 52 determines whether the traveling road is an uphill road or a downhill road based on the estimated slope value, and changes the shift pattern of the transmission 12 based on the determination result. Specifically, in the case of an uphill road, the traveling control unit 52 suppresses upshifting to maintain a necessary driving force, and prevents repetition of upshifting and downshifting. In the case of a downhill road, the traveling control unit 52 performs control so that the gear position is maintained on the low speed side in order to maintain the engine braking force.

  FIG. 3 is a functional block diagram showing a configuration of the road surface gradient estimation apparatus according to the embodiment of the present invention.

  The road surface gradient estimation device according to the present embodiment includes a vehicle speed sensor 21, an acceleration sensor 24, a yaw rate sensor 25, and a road surface gradient estimation processing unit 51.

  The road surface gradient estimation processing unit 51 includes an acceleration calculation unit 511 (calculation unit), a low-pass filter (LPF) 512 (filter unit), a road surface gradient estimation unit 513 (estimation unit), and a filter characteristic change unit 514 (change unit). And a turning time determination unit 515 (determination means) as functional elements. Each function of these functional elements 511 to 515 may be realized by the CPU of the ECU 50 executing a computer program stored in the memory (ROM or RAM) of the ECU 50, or hardware mounted on the ECU 50. It may be realized by.

  The acceleration calculation unit 511 calculates the longitudinal acceleration (calculated acceleration) of the vehicle 1 by differentiating the vehicle speed detected by the vehicle speed sensor 21 with respect to time.

  The low-pass filter 512 performs filter processing for removing noise components on the acceleration (detected acceleration) detected by the acceleration sensor 24 and the calculated acceleration output from the acceleration calculation unit 511.

  The road surface gradient estimation unit 513 estimates the road surface gradient based on the output of the low-pass filter 512, that is, the detected acceleration after the filtering process and the calculated acceleration after the filtering process. Specifically, the road surface gradient estimation unit 513 obtains a gravitational acceleration component by taking the difference between the detected acceleration after filtering and the calculated acceleration after filtering, and estimates the road gradient based on the obtained gravitational acceleration component. To do.

  The turning determination unit 515 determines, for example, whether the vehicle 1 is turning based on the turning angular velocity detected by the yaw rate sensor 25. Specifically, the turning determination unit 515 determines that the vehicle 1 is turning when the turning angular velocity exceeds a predetermined value (for example, 0). The turning determination unit 515 inputs data indicating the determination result to the filter characteristic changing unit 514.

  The filter characteristic changing unit 514 changes the characteristics of the filter processing by the low-pass filter 512 based on the determination result of the turning time determining unit 515. Specifically, when it is determined that the vehicle 1 is turning, the filter characteristic changing unit 514 changes the time constant in the filter process to a value larger than the default value employed during normal time, Increase noise reduction effect. Note that the default value of the time constant in the filter processing is determined in consideration of both the noise removal effect and the responsiveness of the road surface gradient estimation processing.

  For example, when it is determined that the vehicle 1 is turning, the filter characteristic changing unit 514 is based on the acquired turning angular velocity, that is, the turning angular velocity detected by the yaw rate sensor 25 in the present embodiment. A constant may be determined. Specifically, the filter characteristic changing unit 514 may determine the changed time constant so that the time constant in the filter processing increases as the acquired turning angular velocity increases. For example, the filter characteristic changing unit 514 holds in advance a map indicating a correspondence relationship between a plurality of ranges related to the turning angular velocity and a time constant set when the turning angular velocity is within the range, and based on this map. The time constant after change may be determined.

  Further, for example, when it is determined that the vehicle 1 is turning, the filter characteristic changing unit 514 gradually sets the time constant in the filter process at predetermined time intervals until reaching an upper limit value larger than the default value. You may enlarge it.

  Generally, when a vehicle 1 turns, a lateral force is applied to the vehicle 1, so that noise superimposed on the detected acceleration and the calculated acceleration increases. Therefore, according to the above configuration, the characteristic of the filter processing is changed to a value that places more importance on the noise removal effect when the vehicle 1 is turning, where the noise superimposed on the detected acceleration and the calculated acceleration is large. Can be removed appropriately, and the road surface gradient can be estimated with high accuracy.

  If it is determined that the vehicle 1 is not turning at the normal time, the time constant in the filter process is set to a default value, and both the noise removal effect and the response of the road surface gradient estimation process are equally emphasized. The

  Next, filter characteristic change processing according to an embodiment of the present invention will be described.

  FIG. 4 is a flowchart of the filter characteristic changing process according to the embodiment of the present invention.

  This filter characteristic changing process is repeatedly executed at a predetermined calculation cycle.

  First, the turning time determination unit 515 determines whether or not the vehicle 1 is turning based on the turning angular velocity detected by the yaw rate sensor 25 (step S10).

  If it is determined in step S10 that the vehicle 1 is turning (step S10: YES), the filter characteristic changing unit 514 changes the time constant in the filter processing by the low-pass filter 512 to a value larger than the default value. (Step S11). That is, when it is determined that the vehicle 1 is turning, the characteristics of the filter processing by the low-pass filter 512 are changed so that the noise removal effect is more important.

  In step S <b> 11, the filter characteristic changing unit 514 may determine the changed time constant based on the turning angular velocity detected by the yaw rate sensor 25. Specifically, the filter characteristic changing unit 514 may determine the changed time constant so that the time constant in the filter processing increases as the turning angular velocity increases. Thereafter, the process of step S10 is performed again.

  On the other hand, if it is not determined in step S10 that the vehicle 1 is turning (step S10: NO), the filter characteristic changing unit 514 sets the time constant in the filter processing by the low-pass filter 512 to a default value (step S10). S12). Thereafter, the process of step S10 is performed again.

  As described above, the road surface gradient estimation device according to the present embodiment increases the time constant in the filter process when turning the vehicle 1 in which the noise superimposed on the detected acceleration and the calculated acceleration is large, thereby reducing the noise removal effect in the filter process. Strengthen. Thereby, even when the vehicle 1 is turning, the noise component superimposed in the filter process can be appropriately removed, and the gradient of the road surface on which the vehicle 1 travels can be accurately estimated.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

  For example, in the above embodiment, the filter characteristic changing unit 514 increases the time constant in the filter process when it is determined that the vehicle 1 is turning, but the present invention is not limited to this. For example, the filter characteristic changing unit 514 may reduce the time constant in the filter process when it is determined that the vehicle 1 is not turning.

  Further, in the above embodiment, the turning time determination unit 515 determines whether or not the vehicle 1 is turning based on the turning angular velocity detected by the yaw rate sensor 25, but the present invention is not limited to this. For example, the vehicle 1 is provided with a lateral acceleration sensor, a steering angle sensor, or a wheel speed sensor, and the turning time determination unit 515 includes a lateral acceleration detected by the lateral acceleration sensor, a steering angle detected by the steering angle sensor, or a wheel. Whether or not the vehicle 1 is turning may be determined based on the difference between the left and right wheel speeds detected by the speed sensor. Specifically, the turning determination unit 515 may determine that the vehicle 1 is turning when the difference in lateral acceleration, steering angle, or left and right wheel speeds exceeds a predetermined value.

  For example, the turning time determination unit 515 may determine whether or not the vehicle 1 is turning based on the blinker information stored in the memory of the ECU 50. Here, the winker information is information indicating whether the winker is ON or OFF. For example, when the winker is operated, a signal indicating the state after the operation (ON or OFF) is transmitted to the ECU 50, and the content of the winker information is updated based on the signal. The turn determination unit 515 determines that the vehicle 1 is turning when the turn signal information indicates that the turn signal is ON, and determines that the vehicle 1 is not turning when the turn signal information indicates that the turn signal is OFF. May be.

  Moreover, in the said embodiment, although the turning angular velocity for determining the time constant after a change was detected by the yaw rate sensor 25, this invention is not limited to this. For example, the turning angular velocity is calculated based on the vehicle speed detected by the vehicle speed sensor 21 and the lateral acceleration detected by a lateral acceleration sensor (not shown) or based on the left and right wheel speeds detected by a wheel speed sensor (not shown). May be.

1 Vehicle 10 Engine 11 Clutch 12 Transmission 13 Propeller Shaft 14 Differential Device 15 Drive Shaft 21 Vehicle Speed Sensor 24 Acceleration Sensor 25 Yaw Rate Sensor 50 ECU
511 Acceleration calculation unit 512 Low-pass filter 513 Road surface gradient estimation unit 514 Filter characteristic change unit 515 Turning determination unit

Claims (3)

First detecting means for detecting the vehicle speed of the vehicle;
Second detection means for detecting acceleration in the longitudinal direction of the vehicle;
Third detection means for detecting a value for determining whether or not the vehicle is turning;
Calculating means for calculating acceleration in the front-rear direction of the vehicle based on the vehicle speed detected by the first detecting means;
Filter means for applying a filter process for removing a noise component to each of the acceleration detected by the second detection means and the acceleration calculated by the calculation means;
Estimating means for estimating a slope of a road surface on which the vehicle travels based on an output value of the filter means;
Determination means for determining whether or not the vehicle is turning based on a detection value of the third detection means;
A road surface gradient estimation device comprising: changing means for changing characteristics of the filter processing based on a determination result of the determination means. The road surface gradient estimation device according to claim 1, wherein the change unit increases a time constant in the filter processing when a determination result of the determination unit is positive. An acquisition means for acquiring an angular velocity of the turning of the vehicle;
The road surface gradient estimation device according to claim 2, wherein the changing unit determines a time constant after the change based on the angular velocity acquired by the acquiring unit.

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