JP2008006954A - Controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily use detection information on road surface irregularity from four-wheels for various control objects of the vehicle. <P>SOLUTION: A vehicle body motion model to which an engine torque and a steering angle are input as information of typical vehicle drive state which may cause up-and-down motion of a vehicle body and which outputs suspension displacement quantity C of each wheel due to the up-and-down motion of the vehicle body is stored in a memory of ECU 40. During running of the vehicle, the engine torque and the steering angle are input into the vehicle body motion model and the suspension displacement quantity C due to the up-and-down motion of the vehicle body is computed. The difference (A-C) between the suspension displacement quantity A of each wheel detected by a suspension displacement sensor 43 of each wheel and the suspension displacement quantity C of each wheel due the up-and-down motion of the vehicle body estimated by the vehicle body motion model is calculated as suspension displacement quantity B due to the road surface irregularity of each wheel (road surface irregularity degree of each wheel) and suspension displacement quantity B of each wheel is weighted and averaged to find road surface irregularity random property. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control device having a function of detecting information related to unevenness of a traveling road surface.

  In recent years, electronically controlled driving control technology for automobiles has been developed to detect driving road surface irregularities in order to improve driving stability and riding comfort, and to control electronic suspension and engine torque according to the degree of irregularities. There is something to control.

The conventional road surface unevenness detection technology includes, for example, a suspension displacement sensor for detecting a suspension displacement amount in each of the left and right front wheel suspension devices, and a vehicle body as described in Patent Document 1 (Japanese Patent Laid-Open No. 5-319054). And an acceleration sensor for detecting the vertical acceleration of the vehicle, and by processing the output of each sensor with a vibration input / output circuit, the road surface unevenness with which the front wheel contacts is detected and the road surface unevenness with which the front wheel is in contact with the rear wheel The delay time until the vehicle touches is calculated based on the vehicle speed, and the road surface unevenness detection information that the front wheel contacts is used as the road surface unevenness detection information that the rear wheel contacts as it is, and the road surface that has been in the past for the delay time There is one in which the suspension device for the rear wheel is electronically controlled based on the detection information of the unevenness.
JP-A-5-319054 (first page to fourth page, etc.)

  By the way, when the vehicle is traveling straight ahead, the trajectories of the front wheels and the rear wheels overlap with each other in a straight line, so that the rear wheels also contact the road surface irregularities that the front wheels contact. For this reason, the detection information on the road surface unevenness with which the front wheel contacts can be used as detection information for the road surface unevenness with which the rear wheel contacts. However, when the vehicle is turning, as shown in FIG. 6, the trajectory of the front wheels and the trajectory of the rear wheels differ depending on the so-called inner wheel difference. If this detection information is used as detection information for road surface unevenness with which the rear wheel contacts, the rear wheel side will be controlled using detection information for road surface unevenness with which the rear wheel does not contact, and the control characteristics will deteriorate. A problem occurs. Such a problem occurs not only when the vehicle is turning, but also when, for example, the vehicle is skid (when slipping) or when the road surface shape of the unpaved road is deformed by the front wheels.

  In order to solve this problem, it is conceivable to detect the road surface unevenness on the rear wheel side by the same method as the detection method of the road surface unevenness on the front wheel side. Therefore, even if the detection information of road surface unevenness is reflected in misfire detection or engine control, it becomes a problem how to reflect the detection information of 4 types of road surface unevenness, and the control becomes complicated. There is a drawback.

  The present invention has been made in consideration of such circumstances. Therefore, the object of the present invention is to be able to collect and detect the degree of unevenness of the road surface in contact with all wheels in one piece of information. An object of the present invention is to provide a vehicular control device that makes it easy to use detection information on road surface unevenness of four wheels as a control target.

  In order to achieve the above object, the invention according to claim 1 is directed to a suspension displacement detection means for each wheel for detecting a suspension displacement amount (vehicle height displacement amount) for each of the front, rear, left and right wheels of the vehicle, Road surface unevenness randomness calculating means for calculating a parameter (hereinafter referred to as “road surface unevenness randomness”) for comprehensive evaluation of road surface unevenness with which each wheel contacts based on the suspension displacement amount of each wheel detected by the suspension displacement amount detecting means; It is set as the structure provided with. In this configuration, since one road surface irregularity randomness is calculated based on the suspension displacement amount of each wheel detected by the suspension displacement amount detecting means of each wheel, the degree of unevenness of the road surface with which all the wheels are in contact with one piece of information ( Road surface unevenness) can be detected in a collective manner, and the detection information of the road surface unevenness of the four wheels can be easily used in various control objects of the vehicle.

  In this case, for example, in addition to the suspension displacement sensor (suspension displacement detection means), a vehicle body acceleration sensor for detecting the vertical acceleration of the vehicle body is provided for each wheel, and the output signal of the suspension displacement sensor and the vehicle acceleration sensor The degree of unevenness of the traveling road surface may be detected for each wheel based on the output signal.

  However, this configuration requires two types of sensors, that is, a suspension displacement sensor and a vehicle body acceleration sensor, and has the disadvantage of increasing costs.

  Further, it is conceivable to extract the specific frequency acceleration component as the road surface unevenness component by filtering the output signal of the acceleration sensor provided for each wheel and detect the road surface unevenness for each wheel.

  However, with this configuration, the output signal of the acceleration sensor varies greatly depending on the vehicle speed even when the road surface unevenness level is the same, so it is difficult to stably and accurately detect the road surface unevenness level without being affected by the vehicle speed. In particular, since the output signal of the acceleration sensor becomes small at low speeds, there is a drawback that it is difficult to detect road surface irregularities. In addition, the road surface unevenness cannot be detected in real time because the road surface unevenness can only be detected after the wheel has overcome the road surface unevenness several times and the output signal of the acceleration sensor vibrates several times. There is also a disadvantage that the control information for the road surface unevenness is also bad because the detection information of the road surface unevenness is reflected in the control after the influence of the road surface unevenness appears greatly.

  In order to eliminate these drawbacks, as in claim 2, the vehicle vertical movement of the vehicle body is input by inputting information on the current vehicle driving state into a vehicle body movement model that simulates the vertical movement of the vehicle body that changes according to the vehicle driving state. A vehicle body vertical motion estimation means for estimating the vehicle body vertical motion estimation means, wherein the road surface unevenness randomness calculation means includes a suspension displacement amount of each wheel detected by the suspension displacement amount detection means and a vertical motion of the vehicle body estimated by the vehicle body vertical motion estimation means. Based on the above, the road surface unevenness degree is estimated for each wheel, and the road surface unevenness randomness is calculated based on the estimated value of the road surface unevenness degree of each wheel.

  In this configuration, the vertical motion of the vehicle body is estimated from the vehicle driving state information by the vehicle body motion model, so the vehicle body acceleration sensor required in the conventional road surface unevenness detection technology becomes unnecessary, and there is a demand for reduction in the number of sensors and cost reduction. Can be satisfied. In addition, the suspension displacement amount (vehicle height displacement amount) detected by the suspension displacement amount detecting means for each wheel can be detected almost in real time without being affected by the vehicle speed, and information on the vehicle operating state can be obtained from the vehicle body motion model. The vertical movement of the vehicle body estimated from the above can also be estimated almost in real time without being affected by the vehicle speed. Therefore, based on the detected value of the suspension displacement (vehicle height displacement amount) and the estimated value of the vertical movement of the vehicle body, The degree of unevenness can be estimated almost in real time without being affected by the vehicle speed. This makes it possible to accurately and responsively estimate the road surface unevenness degree of each wheel without being affected by the vehicle speed while meeting the demand for cost reduction with a small number of sensors, and estimating the road surface unevenness degree of each wheel. Based on the value, the road surface unevenness randomness can be calculated with high accuracy and good response.

  In this case, in consideration of the fact that the traveling vehicle body moves up and down due to a change (acceleration / deceleration) of the engine torque as a drive source, the vehicle body motion model is the vehicle operation as an input as in claim 3. It is preferable that the state information includes at least the engine torque and outputs a suspension displacement amount estimated value (vehicle height displacement amount estimated value) of each wheel due to the vertical movement of the vehicle body generated in the vehicle driving state. Thus, if the suspension displacement amount (vehicle height displacement amount) of each wheel due to the vertical movement of the vehicle body is estimated using the engine torque, the suspension displacement amount of each wheel generated during acceleration / deceleration can be accurately estimated. .

  Here, either the required engine torque (target engine torque) or the actual engine torque (actually generated engine torque) may be used as the engine torque, but the required engine torque is used from the viewpoint of improving detection response. Is desirable. Since the required engine torque is calculated before the engine torque corresponding to it is actually generated, if the required engine torque is used, the upper and lower parts of the vehicle generated by the actual engine torque are generated even before the actual engine torque is generated accordingly. There is an advantage that motion can be predicted. If the output of the vehicle body motion model is the estimated value of the suspension displacement amount of each wheel due to the vertical movement of the vehicle body, the suspension displacement amount of each wheel detected by the suspension displacement detection means of each wheel and the suspension displacement amount estimation of each wheel The road surface unevenness degree of each wheel can be easily estimated from the value.

  Further, considering that the traveling vehicle body moves up and down according to the steering angle of the steering wheel, the vehicle body motion model has at least a steering angle as information on the vehicle driving state to be input. In addition, an estimated value of the suspension displacement amount of each wheel due to the vertical movement of the vehicle body generated in the vehicle driving state may be output. Thus, if the amount of suspension displacement of each wheel due to the vertical movement of the vehicle body is estimated using the steering angle, the amount of suspension displacement of each wheel that occurs when the vehicle turns can be accurately estimated.

  The suspension displacement amount A generated when the wheels get over the road surface unevenness during traveling of the vehicle is the total displacement amount (A) of the suspension displacement amount B (road surface unevenness degree) due to the road surface unevenness and the suspension displacement amount C due to the vertical movement of the vehicle body. = B + C).

  Considering this point, as in claim 5, the suspension displacement amount A of each wheel detected by the suspension displacement detection unit of each wheel and the vertical movement of the vehicle body estimated by the vehicle body vertical motion estimation unit, The road surface unevenness degree B of each wheel may be estimated based on the difference (A−C) from the estimated suspension displacement amount C. Thereby, the road surface unevenness degree B of each wheel can be estimated very easily.

  In addition, as described in claim 6, the road surface unevenness randomness calculating means uses a weighting correction coefficient set for each wheel according to the degree to which the road surface unevenness degree of each wheel affects the control of the control target of the vehicle. It is also possible to perform a process of weighted averaging the estimated value of the road surface unevenness degree of each wheel, and the weighted average value may be the road surface unevenness randomness.

  In this case, in order to simplify the calculation process, the weight correction coefficient of each wheel may be a predetermined constant value. However, as described in claim 7, the road surface irregularity randomness calculating means performs weighting of each wheel. It is preferable to variably set the correction coefficient according to the driving conditions of the vehicle (for example, steering angle, acceleration / deceleration, vehicle speed, etc.).

  For example, when the vehicle is turning rightward, the load applied to the left front and rear wheels due to centrifugal force increases. It is good to calculate. Further, since the load applied to the left and right rear wheels increases during acceleration, it is preferable to calculate the road surface irregularity randomness by increasing the weighting correction coefficient for the left and right rear wheels compared to the constant speed traveling. Similarly, since the load applied to the left and right front wheels increases during deceleration, it is preferable to calculate the road surface unevenness randomness by increasing the weighting correction coefficient for the left and right front wheels as compared to when driving at a constant speed. In this way, the weighting correction coefficient for each wheel can be appropriately variably set according to the driving conditions of the vehicle.

  Further, as in claim 8, the road surface unevenness randomness calculating means performs a process of calculating an arithmetic average, a geometric average, or a harmonic average of the estimated values of the road surface unevenness of each wheel, and calculating the average value of the road surface unevenness random You may make it sex.

  Alternatively, as in claim 9, the road surface unevenness randomness calculating means calculates any one of a maximum value, a minimum value, and a median value (second or third value) of the estimated value of the road surface unevenness degree of each wheel. You may make it select as said road surface unevenness randomness.

  Alternatively, as described in claim 10, the road surface unevenness calculating means calculates a frequency distribution of estimated values of the road surface unevenness degree of each wheel in a past predetermined period, and sets the mode value as the road surface unevenness randomness. You may make it select.

  According to another aspect of the present invention, the road surface unevenness randomness calculating means includes a plurality of calculation means for calculating the road surface unevenness randomness by different methods, and the calculation means is switched according to driving conditions of the vehicle. May be. In this way, it is possible to select a road surface unevenness randomness calculation method most suitable for the driving condition of the vehicle at that time from among a plurality of road surface unevenness randomness calculation methods.

  According to a twelfth aspect of the present invention, it is preferable that the road surface unevenness correcting unit corrects information used for controlling the control target of the vehicle in consideration of the road surface unevenness randomness calculated by the road surface unevenness randomness calculating unit. Thereby, the road surface unevenness degree which 4 wheels contact can be easily reflected in control of the control object of a vehicle.

  For example, in a system having misfire determination means for determining whether or not misfiring has occurred by comparing the engine rotation variation amount with a misfire determination value as in claim 13, the engine rotation variation amount of each cylinder due to road surface unevenness of each wheel It is preferable that the engine rotation fluctuation amount or the misfire determination value is corrected based on the road surface unevenness randomness calculated by the road surface unevenness randomness calculating means. This makes it possible to reduce the influence of the road surface unevenness on the engine rotational fluctuation amount even during rough road driving in which the engine rotational fluctuation amount changes due to the road surface unevenness, and to accurately determine whether each cylinder has misfired. it can.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. On the downstream side of the air flow meter 14, a throttle valve 15 whose opening is adjusted by a motor or the like and a throttle opening sensor 16 for detecting the throttle opening are provided.

  Further, a surge tank 17 is provided on the downstream side of the throttle valve 15, and an intake pipe pressure sensor 18 for detecting the intake pipe pressure is provided in the surge tank 17. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 19 of each cylinder. Yes. During engine operation, the fuel in the fuel tank 21 is sent to the delivery pipe 23 by the fuel pump 22 and fuel is injected from the fuel injection valve 20 of each cylinder at each injection timing of each cylinder. A fuel pressure sensor 24 that detects fuel pressure (fuel pressure) is attached to the delivery pipe 23.

  Further, the engine 11 is provided with variable valve timing mechanisms 27 and 28 for changing the opening and closing timings of the intake valve 25 and the exhaust valve 26, respectively. Further, the engine 11 is provided with an intake cam angle sensor 31 and an exhaust cam angle sensor 32 that output a cam angle signal in synchronization with the rotation of the intake cam shaft 29 and the exhaust cam shaft 30, and the rotation of the crank shaft of the engine 11. Is provided with a crank angle sensor 33 for outputting a pulse of a crank angle signal at every predetermined crank angle (for example, every 30 ° C. A).

  On the other hand, an air-fuel ratio sensor 37 for detecting the air-fuel ratio of the exhaust gas is installed in the exhaust collecting portion 36 where the exhaust manifold 35 of each cylinder of the engine 11 gathers. A catalyst 38 such as a three-way catalyst for purifying CO, HC, NOx and the like is provided.

  In addition, this engine control system includes a vehicle speed sensor 41 that detects the vehicle speed, a steering sensor 42 that detects the steering angle of the steering wheel, and a suspension displacement amount of each wheel on the front, rear, left, and right of the vehicle (between each wheel and the vehicle body). Suspension displacement sensor 43 (suspension displacement amount detection means) for detecting the relative displacement amount in the vertical direction) is provided.

  In this case, the suspension displacement sensor 43 is provided in each of the four-wheel suspension devices of the vehicle. The suspension displacement sensor 43 of each wheel converts, for example, the amount of relative displacement in the vertical direction of the suspension arm of each wheel with respect to the vehicle body into a rotation angle by a link mechanism connected therebetween, and the change in the rotation angle is converted into an angle. Use a sensor configured to detect the sensor, or attach an ultrasonic sensor in the vicinity of each wheel of the vehicle body so as to face the road surface, emit ultrasonic waves toward the road surface, and reflect from the road surface. You may use what was constituted so that the amount of suspension displacement of each wheel may be detected from the propagation time by measuring the propagation time until a wave is received. In short, the suspension displacement sensor 43 for each wheel can detect any amount of suspension displacement for each wheel (the relative displacement in the vertical direction between each wheel and the vehicle body) or information correlated therewith in real time. Various detection methods may be used.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 40. The ECU 40 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the throttle opening degree and the fuel injection of each cylinder according to the engine operating state. The fuel injection amount and ignition timing of the valve 20 are controlled.

  The ECU 40 executes a road surface irregularity randomness calculation routine shown in FIG. 2 to be described later, thereby estimating the suspension displacement amount (vehicle height displacement amount) detected by the suspension displacement sensor 43 of each wheel and the vehicle body motion model. The road surface unevenness degree is estimated for each wheel on the basis of the suspension displacement amount of each wheel due to the vertical movement of the vehicle body.

  In this case, the vehicle body motion model takes as input u engine torque, which is information about typical vehicle operating conditions that cause the vehicle body to move up and down, and the amount of suspension displacement due to the vehicle body vertical motion generated by this engine torque. The output y is an autoregressive model (AR model). This model is defined as follows.

A (q) y (t) = B (q) u (t)
A (q) = 1 + a1 q ^-1 + a2 q ^-2 + a3 q ^-3 + a4 q ^-4 + a5 q ^-5 + a6 q ^-6
B (q) = b1 q ^-1 + b2 q ^-2 + b3 q ^-3
Here, q is a shift operator, and q ⁻ⁿ represents the input u or output y n times before.

Therefore, A (q) y (t) and B (q) u (t) are specifically expressed as follows.
A (q) y (t) = y (t) + a1 y (t-1) + a2 y (t-2)
+ A3 y (t-3) + a4 y (t-4) + a5 y (t-5) + a6 y (t-5) B (q) u (t) = b1 u (t-1) + b2 u (t-2) ) + B3 u (t-3)

  The parameters a1 to a6 and b1 to b3 of the vehicle body motion model expressed by the above equation are determined in advance by a system identification method in an adaptation process or the like. The vehicle body motion model is stored in the ROM of the ECU 40 or a rewritable nonvolatile memory.

  FIG. 5 is a diagram showing a comparison between model output and actual machine data when the engine torque is input to the vehicle body motion model and the suspension displacement amount due to the vertical motion of the vehicle body is calculated using the vehicle body motion model. If a vehicle body motion model using engine torque as an input is used, it is possible to accurately estimate the amount of suspension displacement due to the vertical motion of the vehicle body caused by changes in engine torque during acceleration / deceleration.

  Here, either the required engine torque (target engine torque) or the actual engine torque (actually generated engine torque) may be used as the engine torque, but the required engine torque is used from the viewpoint of improving detection response. Is desirable. Since the required engine torque is calculated before the engine torque corresponding to it is actually generated, if the required engine torque is used, the upper and lower parts of the vehicle generated by the actual engine torque are generated even before the actual engine torque is generated accordingly. Can predict movement.

  Similarly, a vehicle body motion model (autoregressive model) is constructed by system identification that takes the steering angle detected by the steering sensor 42 as an input and outputs the suspension displacement amount of each wheel due to the vertical motion of the vehicle body caused by the steering angle. Alternatively, it may be stored in the ROM of the ECU 40 or a rewritable nonvolatile memory, and the suspension displacement amount of each wheel due to the vertical movement of the vehicle body may be estimated from the steering angle while the vehicle is running. If the suspension displacement amount of each wheel due to the vertical movement of the vehicle body is estimated using the steering angle, the suspension displacement amount of each wheel generated when the vehicle turns can be estimated with high accuracy.

  When estimating the suspension displacement of each wheel due to the vertical motion of the vehicle body considering both the engine torque and the steering angle, the suspension displacement of each wheel due to the vertical motion of the vehicle body estimated by the vehicle motion model using the engine torque as input The amount of suspension displacement of each wheel due to the vertical movement of the vehicle body estimated by the vehicle body movement model with the steering angle as an input is used as the suspension displacement amount of each wheel due to the final vertical movement of the vehicle body You can do it.

  Alternatively, in addition to the engine torque and steering angle, a vehicle body motion model is created that inputs, for example, the amount of brake operation (braking force), vehicle speed, etc. as information on the vehicle operating state that causes the vehicle body to move up and down. The suspension displacement amount of each wheel due to the vertical movement of the vehicle body estimated from the brake operation amount (braking force), the vehicle speed, and the like may be taken into consideration.

  The suspension displacement amount A of each wheel generated when the wheel gets over the road surface unevenness while the vehicle is traveling is the suspension displacement amount B (road surface unevenness degree) of each wheel due to the road surface unevenness and the suspension displacement of each wheel due to the vertical movement of the vehicle body. The total displacement amount with the amount C (A = B + C) is considered.

  In consideration of this point, the ECU 40 determines the difference between the suspension displacement amount A of each wheel detected by the suspension displacement sensor 43 of each wheel and the suspension displacement amount C of each wheel due to the vertical movement of the vehicle body estimated by the vehicle body motion model ( AC) is calculated as a suspension displacement amount B (degree of road surface unevenness of each wheel) due to road surface unevenness of each wheel.

  By the way, when the suspension device or the like deteriorates with time, the vertical motion (suspension displacement) of the vehicle body changes depending on the vehicle operating state. The estimation accuracy of the degree of road surface unevenness is reduced.

  As a countermeasure, in this embodiment, the ECU 40 executes a vehicle body motion model update routine shown in FIG. 3 to be described later. During a period in which the suspension displacement amount B due to road surface unevenness of each wheel can be regarded as almost zero, input and output data of the vehicle body motion model is stored in a rewritable nonvolatile memory of the ECU 40, and the vehicle body motion is based on the stored data. The model parameters a1 to a6 and b1 to b3 are sequentially updated.

  Further, in this embodiment, in order to make it easy to use the detection information of the road surface unevenness degree of the four wheels in various control objects of the vehicle, a parameter for comprehensive evaluation of the road surface unevenness degree of each wheel (hereinafter referred to as “road surface unevenness randomness”). Is calculated by one of the following methods.

[Road surface irregularity randomness calculation method (1)]
The estimated value of the road surface unevenness of each wheel is obtained using the weighting correction coefficients a, b, c, d set for each wheel according to the degree that the road surface unevenness degree affects the control of the vehicle control target. A process of weighted averaging is performed, and the weighted average value is defined as road surface unevenness randomness.

Road surface unevenness = a × road surface unevenness degree of left front wheel + b × road surface unevenness degree of right front wheel
+ C × left rear wheel road surface unevenness degree + d × right rear wheel road surface unevenness degree Here, the weighting correction coefficients a, b, c, and d are set to be a + b + c + d = 1. However, when traveling at high speed, a + b + c + d <1 may be set.

  In this case, the weighting correction coefficients a, b, c, and d of each wheel may be set to a predetermined constant value in order to simplify the arithmetic processing, but the weighting correction coefficients a, b, c, and d of each wheel. Is preferably variably set in accordance with the driving conditions of the vehicle (for example, steering angle, acceleration / deceleration, vehicle speed, etc.).

  For example, when the vehicle is turning in the right direction, the load applied to the left front and rear wheels due to centrifugal force increases. Therefore, the weight correction coefficients a and c of the left front and rear wheels are set to be larger than when traveling straight and the road surface unevenness is increased. Randomness should be calculated. In addition, since the load applied to the left and right rear wheels increases during acceleration, it is preferable to calculate the road surface unevenness randomness by increasing the weighting correction coefficients c and d of the left and right rear wheels as compared to when driving at a constant speed. Similarly, since the load applied to the left and right front wheels increases during deceleration, it is preferable to calculate the road surface unevenness randomness by increasing the weighting correction coefficients a and b of the left and right front wheels compared to when driving at a constant speed. In this way, the weight correction coefficients a, b, c, and d for each wheel can be appropriately variably set according to the driving conditions of the vehicle.

[Road surface unevenness randomness calculation method (2)]
A process of calculating an arithmetic average, a geometric average, or a harmonic average of the estimated values of the road surface unevenness of each wheel is performed, and the average value is set as the road surface unevenness randomness.
Here, if the estimated values of the road surface unevenness degree of each wheel are x1, x2, x3, and x4, the arithmetic mean, geometric mean, and harmonic mean are calculated by the following equations (1) to (3), respectively.

  It should be noted that the average value calculation processing may be switched to any one of arithmetic average, geometric average, and harmonic average according to the driving conditions of the vehicle (for example, steering angle, acceleration / deceleration, vehicle speed, etc.).

[Road surface irregularity randomness calculation method (part 3)]
Any one of a maximum value, a minimum value, and a median value (second or third value) of estimated values of the road surface unevenness degree of each wheel is selected as the road surface unevenness randomness. In this case as well, the maximum value, the minimum value, or the median value may be switched according to the driving conditions of the vehicle (for example, steering angle, acceleration / deceleration, vehicle speed, etc.).
[Road surface unevenness calculation method (part 4)]
The frequency distribution of the estimated value of the road surface unevenness degree of each wheel in the past predetermined period is calculated, and the mode value is selected as the road surface unevenness randomness.

[Road Surface Roughness Randomness Calculation Method (Part 5)]
Of the plurality of road surface unevenness randomness calculation methods for calculating the road surface unevenness randomness using different methods, the road surface unevenness randomness calculation that is most suitable for the driving conditions of the vehicle at the time (for example, steering angle, acceleration / deceleration, vehicle speed, etc.) is calculated. Select the method to calculate the road surface unevenness randomness.

  The ECU 40 corrects information used for controlling the control target of the vehicle using the road surface unevenness randomness calculated by any one of the above-described road surface unevenness randomness calculation methods (Part 1) to (Part 5). In this embodiment, when the misfire detection routine of FIG. 4 described later compares the engine rotation fluctuation amount of each cylinder with the misfire determination value to determine the presence or absence of misfire in each cylinder, the road surface unevenness of each wheel causes the unevenness of each cylinder. In consideration of changes in the engine rotation fluctuation amount, the engine rotation fluctuation amount is corrected based on the road surface unevenness randomness. The influence on the engine rotation fluctuation amount of each cylinder is reduced.

Instead of correcting the engine rotation fluctuation amount based on the road surface unevenness randomness, the misfire determination value may be corrected based on the road surface unevenness randomness. In this case, the same effect can be obtained. Can do.
Hereinafter, the processing content of each routine of FIG. 2 thru | or FIG. 4 which ECU40 performs is demonstrated.

[Routine unevenness calculation routine]
The road surface unevenness randomness calculation routine of FIG. 2 is executed at a predetermined period during engine operation, and serves as road surface unevenness randomness calculation means in the claims. When this routine is started, first, in step 101, the engine torque (requested engine torque or actual engine torque), which is information on typical vehicle operating conditions that cause the vertical movement of the vehicle body, and the steering sensor 42 are used. The detected steering angle is read, and the suspension displacement amount A of each wheel detected by the suspension displacement sensor 43 of each wheel is read.

  Thereafter, the process proceeds to step 102, and the suspension displacement amount C of each wheel due to the vertical movement of the vehicle body caused by acceleration / deceleration or vehicle turning is calculated using a vehicle body motion model that receives engine torque and steering angle. The processing in step 102 serves as vehicle body vertical motion estimation means in the claims. Thereafter, the process proceeds to step 103, where the difference (A−C) between the suspension displacement amount A detected by the suspension displacement sensor 43 of each wheel and the suspension displacement amount C of each wheel due to the vertical movement of the vehicle body calculated by the vehicle body motion model is calculated. It is calculated as a suspension displacement amount B due to road surface unevenness of each wheel.

  Thereafter, the process proceeds to step 104, where road surface unevenness randomness is calculated by any one of the above-described road surface unevenness randomness calculation methods (No. 1) to (No. 5).

  The road surface unevenness calculated in this way can be used for, for example, combustion control (misfire detection), suspension control, engine torque control, ABS control, traction control, cruise control, and the like.

[Body movement model update routine]
The vehicle body motion model update routine of FIG. 3 is executed at a predetermined cycle during engine operation. When this routine is started, first, in step 201, the road surface unevenness randomness calculated in the road surface unevenness randomness calculation routine of FIG. 2 is read. In the next step 202, the road surface unevenness randomness is smaller than a predetermined value β. If the road surface unevenness randomness is determined to be equal to or greater than the predetermined value β, it is determined that the rough road has unevenness, and this routine is terminated without performing the subsequent processing.

  On the other hand, if it is determined in step 202 that the road surface irregularity randomness is smaller than the predetermined value β, it is determined that the vehicle is traveling on a flat road, and the process proceeds to step 203 to input data of the current vehicle body motion model. (Engine torque, steering angle), output data, and suspension displacement amount A of each wheel detected by the suspension displacement sensor 43 of each wheel are stored in a rewritable nonvolatile memory of the ECU 40.

Thereafter, the process proceeds to step 204, and it is determined, for example, by the following two conditions (1) and (2) whether or not the vehicle body motion model update condition is satisfied.
(1) Data necessary for identifying parameters a1 to a6 and b1 to b3 of the vehicle body motion model is stored in the nonvolatile memory.
(2) A specified period of time (more than the specified number of trips, more than the specified accumulated mileage) has elapsed since the last vehicle body movement model update Condition that does not satisfy either of these two conditions (1) or (2) If there is, the update condition of the vehicle body motion model is not satisfied, and this routine is finished as it is.

  On the other hand, if the above two conditions (1) and (2) are satisfied at the same time, the vehicle body motion model update condition is satisfied, the process proceeds to step 205, and the data stored in the nonvolatile memory is used. The body motion model parameters a1 to a6 and b1 to b3 are updated by the system identification method.

[Misfire detection routine]
The misfire detection routine of FIG. 4 is executed at predetermined intervals during engine operation, and serves as misfire determination means in the claims. When this routine is started, first, at step 301, the engine rotation fluctuation amount ΔNe is calculated, and at the next step 302, the road surface unevenness randomness calculated by the road surface unevenness randomness calculation routine of FIG.

  Thereafter, the process proceeds to step 303, where it is determined whether or not the road surface unevenness randomness is greater than a predetermined value γ. If the road surface unevenness randomness is equal to or less than the predetermined value γ, it is determined that the vehicle is traveling on a flat road, and step 305 is performed. Then, the engine rotation fluctuation amount ΔNe calculated in step 301 is not corrected and is used as it is as the actual engine rotation fluctuation amount.

On the other hand, if it is determined in step 303 that the road surface unevenness randomness is larger than the predetermined value γ, the process proceeds to step 304, and the engine rotation fluctuation amount ΔNe calculated in step 301 is changed to the road surface unevenness randomness. Subtraction correction is performed using the corresponding road surface unevenness correction value to determine the actual engine rotation fluctuation amount.
Actual engine rotation fluctuation amount = ΔNe−road surface unevenness correction value

  Here, the road surface unevenness correction value is calculated by a table or the like according to the road surface unevenness randomness. The process of step 304 serves as road surface unevenness correcting means in the claims.

  Thereafter, the process proceeds to step 306, and the engine rotation fluctuation amount for each cylinder is calculated using the actual engine rotation fluctuation amount obtained in step 304 or 305. Thereafter, the process proceeds to step 307, where the engine rotation fluctuation amount for each cylinder is compared with the misfire determination value δ. If the engine rotation fluctuation amount for each cylinder is equal to or greater than the misfire determination value δ, it is determined that misfire has occurred ( Step 308) If the engine rotation fluctuation amount for each cylinder is smaller than the misfire determination value δ, it is determined that ignition (no misfire) is made, and this routine is terminated.

  According to the present embodiment described above, the road surface unevenness randomness is calculated as a parameter for comprehensive evaluation of the road surface unevenness with which each wheel comes into contact. Therefore, the degree of unevenness of the road surface with which all the wheels are in contact with one piece of information ( Road surface unevenness) can be detected in a collective manner, and the detection information of the road surface unevenness of the four wheels can be easily used in various control objects of the vehicle.

  In addition, in this embodiment, the vehicle body motion that receives the engine torque and the steering angle, which are typical vehicle driving state information that causes the vertical movement of the vehicle body, and outputs the suspension displacement amount due to the vertical movement of the vehicle body. Using the model, the suspension displacement amount of each wheel due to the vertical movement of the vehicle body is calculated from the engine torque and the steering angle, and the suspension displacement amount of each wheel due to the vertical movement of the vehicle body and the suspension displacement sensor 43 of each wheel detected by each wheel The suspension displacement amount due to the road surface irregularities of each wheel (the degree of road surface unevenness of each wheel) is calculated based on the suspension displacement amount of each wheel, so that the vehicle body acceleration sensor required by the conventional road surface unevenness detection technology becomes unnecessary. It can meet the demands of reducing the number of sensors and reducing the cost.

  Further, the suspension displacement amount of each wheel detected by the suspension displacement sensor 43 of each wheel can be detected almost in real time without being influenced by the vehicle speed, and the vertical motion of the vehicle body estimated from the engine torque and the steering angle by the vehicle body motion model. However, since it can be estimated almost in real time without being affected by the vehicle speed, the road surface unevenness degree of each wheel is not affected by the vehicle speed based on the detected value of the suspension displacement of each wheel and the estimated value of the vertical movement of the vehicle body. Can be estimated in near real time. This makes it possible to accurately and responsively estimate the road surface unevenness degree of each wheel without being affected by the vehicle speed while meeting the demand for cost reduction with a small number of sensors, and estimating the road surface unevenness degree of each wheel. Based on the value, the road surface unevenness randomness can be calculated with high accuracy and good response.

  Further, in this embodiment, the vehicle body movement model is used in a period in which it is determined that the vehicle is traveling on a flat road based on the calculation result of the road surface unevenness, that is, in a period in which the suspension displacement amount B due to the road surface unevenness of each wheel can be regarded as almost zero. The input and output data is stored in a rewritable non-volatile memory, and the parameters of the vehicle body motion model are updated sequentially based on the stored data. Corresponding to changes in vertical motion characteristics, the parameters of the vehicle body motion model can be updated sequentially, preventing a decrease in the estimation accuracy of the road surface unevenness degree of each wheel due to deterioration over time of the suspension device of each wheel. .

  Further, in this embodiment, since the engine rotation fluctuation amount (or misfire determination value) is corrected based on the road surface unevenness randomness, the road surface unevenness is detected even in rough roads in which the engine rotation fluctuation amount changes due to the road surface unevenness. The influence on the rotational fluctuation amount can be reduced, and the presence or absence of misfire in each cylinder can be accurately determined.

  The present invention is not limited to estimating the road surface unevenness degree of each wheel using a vehicle body motion model. For example, in addition to a suspension displacement sensor for each wheel, a vehicle body that detects the acceleration in the vertical direction of the vehicle body An acceleration sensor may be provided, and the road surface unevenness degree of each wheel may be detected based on the output signal of the suspension displacement sensor of each wheel and the output signal of the vehicle body acceleration sensor.

1 is a diagram schematically showing a configuration of an entire engine control system showing an embodiment of the present invention. It is a flowchart which shows the flow of a process of a road surface unevenness | corrugation randomness calculation routine. It is a flowchart which shows the flow of a process of a vehicle body movement model update routine. It is a flowchart which shows the flow of a process of a misfire detection routine. (A) shows an example of the waveform of the input u of the vehicle body motion model, and (b) is a time chart showing an example of the output y of the vehicle body motion model. It is a figure explaining a mode that the locus | trajectory of a front wheel differs from the locus | trajectory of a rear wheel by the inner ring difference at the time of vehicle turning.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 15 ... Throttle valve, 20 ... Fuel injection valve, 40 ... ECU (road surface unevenness randomness calculation means, vehicle body vertical motion estimation means, road surface unevenness correction means, misfire determination means), 41 ... Vehicle speed sensor, 42 ... Steering Sensor, 43 ... Suspension displacement sensor (Suspension displacement detection means)

Claims (13)

Suspension displacement detection means for detecting the suspension displacement of each wheel on the front, rear, left and right of the vehicle,
Road surface unevenness random for calculating a parameter (hereinafter referred to as “road surface unevenness randomness”) for comprehensive evaluation of road surface unevenness with which each wheel contacts based on the suspension displacement amount of each wheel detected by the suspension displacement detection means of each wheel. And a vehicle control device. A vehicle body vertical motion estimation means for estimating the vertical motion of the vehicle body by inputting information on the current vehicle driving state into a vehicle body motion model that simulates the vertical motion of the vehicle body that changes according to the vehicle driving state,
The road surface unevenness randomness calculating means is provided for each wheel based on the suspension displacement amount of each wheel detected by the suspension displacement amount detecting means of each wheel and the vertical movement of the vehicle body estimated by the vehicle body vertical motion estimating means. The vehicle control device according to claim 1, wherein the road surface unevenness degree is estimated for each road, and the road surface unevenness randomness is calculated based on an estimated value of the road surface unevenness degree of each wheel.   The vehicle body movement model includes at least an engine torque as information on the vehicle driving state to be input, and is configured to output an estimated value of a suspension displacement amount of each wheel due to a vertical movement of the vehicle body generated in the vehicle driving state. The vehicle control device according to claim 2, wherein:   The vehicle body movement model includes at least a steering angle as information on the vehicle driving state to be input, and is configured to output an estimated value of a suspension displacement amount of each wheel due to a vertical movement of the vehicle body that occurs in the vehicle driving state. The vehicle control device according to claim 2, wherein the vehicle control device is a vehicle control device.   The road surface unevenness estimation means includes a suspension displacement amount detected by the suspension displacement detection means for each wheel and a suspension displacement estimation value for each wheel due to the vertical movement of the vehicle body estimated by the vehicle body vertical motion estimation means. The vehicle control device according to claim 3, wherein the road surface unevenness degree of each wheel is estimated based on the difference between the two.   The road surface unevenness calculation means calculates the road surface unevenness degree of each wheel using a weighting correction coefficient set for each wheel according to the degree to which the road surface unevenness degree of each wheel affects the control of the control target of the vehicle. The vehicle control device according to any one of claims 2 to 5, wherein a process for performing weighted averaging of the estimated values is performed, and the weighted average value is used as the road surface unevenness randomness.   The vehicle control device according to claim 6, wherein the road surface irregularity randomness calculating unit variably sets a weighting correction coefficient for each wheel according to a driving condition of the vehicle.   The road surface irregularity randomness calculation means performs an arithmetic average, a geometric average, or a harmonic average on an estimated value of the road surface irregularity degree of each wheel, and sets the average value as the road surface irregularity randomness. Item 6. The vehicle control device according to any one of Items 2 to 5.   The road surface unevenness randomness calculating means selects any one of a maximum value, a minimum value, and a median of estimated values of the road surface unevenness degree of each wheel as the road surface unevenness randomness. The vehicle control device according to any one of the above.   The road surface unevenness randomness calculating means calculates a frequency distribution of estimated values of the road surface unevenness degree of each wheel during a predetermined period in the past, and selects the mode value as the road surface unevenness randomness. The control apparatus for vehicles in any one of thru | or 5.   11. The road surface unevenness randomness calculating means includes a plurality of calculation means for calculating the road surface unevenness randomness by different methods, and switches the calculation means according to driving conditions of a vehicle. The vehicle control device according to any one of the above.   12. The road surface unevenness correcting means for correcting information used for controlling the control target of the vehicle in consideration of the road surface unevenness randomness calculated by the road surface unevenness randomness calculating means. The vehicle control device according to claim 1.   A misfire determination means for determining the presence or absence of misfire by comparing the engine rotation fluctuation amount with a misfire determination value, and the road surface unevenness correction means is based on the road surface unevenness randomness calculated by the road surface unevenness randomness calculation means. The vehicle control device according to claim 12, wherein a rotational fluctuation amount or the misfire determination value is corrected.

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