Vehicle suspension control device

Abstract

To make it possible to quickly detect an abnormality of a spring vertical-acceleration sensor that is used for controlling a suspension.SOLUTION: A vehicular suspension control device comprises an actuator that makes control force in a vertical direction act on a space between a spring lower structure and a spring upper structure of a vehicle, at least four spring vertical acceleration sensors, and an electronic control unit. The electronic control unit controls the actuator on the basis of detected acceleration by the at least four spring vertical acceleration sensors. In abnormality detecting processing, the electronic control unit calculates estimated acceleration of spring vertical acceleration at a position of the remaining one spring vertical acceleration sensor, on the basis of the detected acceleration by the spring vertical acceleration sensors which are one less than all of the at least four spring vertical acceleration sensors, and determines whether an abnormal spring vertical acceleration sensor is included in the at least four spring vertical acceleration sensors or not, on the basis of a result of comparison of the calculated estimated acceleration with the detected acceleration by the remaining one spring vertical acceleration sensor.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a vehicle suspension control device including an actuator that applies a vertical control force between an unsprung structure and a sprung structure of a vehicle. [Background technology]

[0002] Patent Document 1 discloses an active suspension device for a vehicle. In this active suspension device, when a vertical acceleration sensor fails, a suspension characteristic control device controls the control gain of the suspension control based on the detection signal of the vertical acceleration sensor to zero. In other words, the suspension control is stopped. More specifically, the failure determination in the active suspension device is performed as follows. That is, when vertical acceleration signals are input from all three vertical acceleration sensors, these vertical acceleration sensors are determined to be normal. On the other hand, when a vertical acceleration signal is not input from any of the three vertical acceleration sensors, the vertical acceleration sensor to which the vertical acceleration signal is not input is determined to have failed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 04-039108 Summary of the Invention [Problem to be solved by the invention]

[0004] The causes of abnormalities in the sprung acceleration sensor (vertical acceleration sensor) include not only the absence of a signal input due to a broken wire or the like, but also, for example, an abnormal signal output from the sprung acceleration sensor. If the output from an abnormal sprung acceleration sensor is used, it becomes impossible to perform appropriate suspension control. For this reason, it is desirable to be able to quickly detect abnormalities in the sprung acceleration sensor.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle suspension control device that can quickly detect an abnormality in a sprung acceleration sensor used to control a suspension actuator. [Means for solving the problem]

[0007] The present disclosure one A vehicle suspension control device according to an embodiment includes an actuator, at least four sprung acceleration sensors, and an electronic control unit. The actuator applies a vertical control force between an unsprung structure and a sprung structure of a vehicle. The at least four sprung acceleration sensors detect vertical acceleration of the sprung structure. The electronic control unit controls the actuator based on the detected accelerations of the at least four sprung acceleration sensors. The electronic control unit executes a sensor identification process. In the sensor identification process, the electronic control unit calculates a specific value that is a related value of a vertical displacement, a roll angle, or a pitch angle at the same position of the sprung structure based on the detected accelerations of the sprung acceleration sensors that is one less than all of the at least four sprung acceleration sensors, for each of a plurality of different combinations of the sprung acceleration sensors that is one less than all of the at least four sprung acceleration sensors, and identifies an abnormal sprung acceleration sensor from among the at least four sprung acceleration sensors based on a comparison of the specific values ​​between the plurality of different combinations.

[0008] This disclosure OtherThe vehicle suspension control device according to the embodiment includes an actuator, at least four sprung acceleration sensors, a gyro sensor, and an electronic control unit. The actuator applies a vertical control force between an unsprung structure and a sprung structure of the vehicle. The at least four sprung acceleration sensors detect vertical acceleration of the sprung structure. The gyro sensor detects an angular velocity of the sprung structure. The electronic control unit controls the actuator based on the detected accelerations of the at least four sprung acceleration sensors. The electronic control unit executes an abnormality detection process. In the abnormality detection process, the electronic control unit calculates a first estimated angular velocity related value of the sprung structure at the position of the gyro sensor based on the detected accelerations of all of the at least four sprung acceleration sensors, and determines whether or not an abnormal sprung acceleration sensor is included among the at least four sprung acceleration sensors based on a comparison between the calculated first estimated angular velocity related value and the detected angular velocity related value of the gyro sensor. Effect of the Invention

[0009] According to the vehicle suspension control device relating to each aspect of the present disclosure, abnormalities in the sprung acceleration sensor can be detected more quickly than in an example in which a process for detecting a sensor abnormality based on the presence or absence of abnormal behavior in the output signal of the sprung acceleration sensor is performed alone using a long judgment time. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a configuration of a vehicle according to a first embodiment. [Diagram 2] 1 is a diagram illustrating an example of a configuration of a suspension according to a first embodiment. [Diagram 3] 4 is a flowchart showing a process related to suspension control according to the first embodiment. [Figure 4] FIG. 11 is a supplementary diagram for explaining the abnormality detection process (step S106). [Diagram 5] FIG. 11 is a supplementary diagram for explaining the sensor identification process according to the second embodiment. [Figure 6] 10 is a flowchart showing a process related to suspension control according to the second embodiment. [Figure 7] FIG. 11 is a diagram illustrating an example of a configuration of a vehicle according to a third embodiment. [Figure 8] 11 is a flowchart showing a process related to suspension control according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the embodiments described below, when reference is made to the number, quantity, amount, range, etc. of each element, the technical idea of ​​this disclosure is not limited to the mentioned numbers, unless otherwise specified or clearly specified in principle to that number.

[0012] 1. First embodiment 1-1.Vehicle configuration FIG. 1 is a diagram showing a schematic example of a configuration of a vehicle 1 according to a first embodiment. The vehicle 1 includes wheels 2 and suspensions 3 that suspend the wheels 2 from a vehicle body 6 (see FIG. 2). The wheels 2 include a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. Suspensions 3FL, 3FR, 3RL, and 3RR are provided for the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR, respectively. In the following description, unless there is a particular need to distinguish between them, each wheel will be referred to as a wheel 2 and each suspension will be referred to as a suspension 3.

[0013] FIG. 2 is a diagram showing an example of the configuration of the suspension 3 according to the first embodiment. The suspension 3 is provided to connect between the unsprung structure 4 and the sprung structure 5 of the vehicle 1. The unsprung structure 4 includes a wheel 2. The sprung structure 5 includes a vehicle body 6. The suspension 3 includes a spring 3S, a damper (shock absorber) 3D, and an actuator 3A. The spring 3S, the damper 3D, and the actuator 3A are provided in parallel between the unsprung structure 4 and the sprung structure 5. The spring 3S has a spring constant K. The damper 3D has a damping coefficient C. The actuator 3A applies a control force Fc in the vertical direction between the unsprung structure 4 and the sprung structure 5. This controls the stroke of the suspension 3.

[0014] More specifically, the actuator 3A is, for example, an electric or hydraulic active actuator (an actuator constituting a so-called full active suspension). However, the "actuator" according to the present disclosure is not particularly limited as long as it can apply a control force Fc in the vertical direction between the unsprung structure 4 and the sprung structure 5. Specifically, the actuator may be, for example, an actuator that varies the damping force generated by the damper 3D, or an actuator of an active stabilizer device. Furthermore, the actuator may be, for example, an actuator (for example, an electric motor) that generates a vehicle longitudinal force (driving force and braking force) acting on the wheels in a vehicle equipped with a suspension configured to be able to convert the vehicle longitudinal force (driving force and braking force) acting on the wheels into a control force Fc by utilizing suspension geometry. The electric motor may be, for example, an in-wheel motor (IWM) provided on the wheels, or an electric motor that can drive the wheels via a vehicle drive shaft.

[0015] Furthermore, the vehicle 1 includes an electronic control unit (ECU) 10. The ECU 10 includes a processor, a storage device, and an input / output interface. The input / output interface receives sensor signals from sensors 12 attached to the vehicle 1, and outputs operation signals to the actuator 3A. The storage device stores various control programs for controlling the actuator 3A. The processor reads out and executes the control programs from the storage device. This realizes suspension control using the actuator 3A. There may be multiple ECUs 10.

[0016] The sensors 12 include, for example, a sprung acceleration sensor that detects the vertical acceleration of the sprung structure 5. In the example shown in FIG. 1, four sprung acceleration sensors 14-i (i=1 to 4) are provided. More specifically, the sprung acceleration sensor 14-1 detects the sprung acceleration at a first position toward the right front wheel 2FR as viewed from the sprung center of gravity position (center of gravity position GC of the sprung structure 5). The sprung acceleration sensor 14-2 detects the sprung acceleration at a second position toward the left front wheel 2FL as viewed from the sprung center of gravity position GC. The sprung acceleration sensor 14-3 detects the sprung acceleration at a third position toward the right rear wheel 2RR as viewed from the sprung center of gravity position GC. The sprung acceleration sensor 14-4 detects the sprung acceleration at a fourth position toward the left rear wheel 2RL as viewed from the sprung center of gravity position GC. That is, the numbers 1 to 4 of the symbol "i" correspond to the right front wheel 2FR, the left front wheel 2FL, the right rear wheel 2RR, and the left rear wheel 2RL, respectively. The distances from the sprung center of gravity position GC to each of the first to fourth positions are arbitrary. The sensors 12 include, for example, a lateral acceleration sensor, a suspension stroke sensor, a vehicle height sensor, an unsprung acceleration sensor, and a wheel speed sensor.

[0017] 1-2.Suspension control The ECU 10 executes suspension control to control the actuator 3A based on the detection signals of the four sprung acceleration sensors 14-i described above. This suspension control includes, as an example, feedback control based on a skyhook control law for reducing vibration of the sprung structure 5 (hereinafter referred to as "FB control of sprung state quantity" or simply "FB control"). Note that, as an example, this FB control is executed for each of the four wheels 2, but instead, for example, it may be executed for only the left and right front wheels 2F or only the left and right rear wheels 2R.

[0018] 1-2-1.Basic configuration example of FB control of sprung mass state quantity In this FB control, the ECU 10 controls the actuator 3A to generate a control force Fc corresponding to a required control amount X required to reduce vibration of the sprung structure 5. In an example described below, the ECU 10 calculates, as the required control amount X, a vertical required control amount Fz, a roll required control amount Mr, and a pitch required control amount Mp, which are required control amounts required to suppress each mode vibration (vertical vibration (heave vibration), roll vibration, and pitch vibration) of the sprung center of gravity position GC.

[0019] The detection value of the sprung acceleration detected by each sprung acceleration sensor 14-i (i=1 to 4) is hereinafter referred to as “detected acceleration Z i The ECU 10 calculates each mode acceleration (i.e., vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g For example, the ECU 10 calculates the vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g The position of each sprung acceleration sensor 14-i (i=1 to 4) in the X direction (the traveling direction of the vehicle 1) and the position in the Y direction (the lateral direction of the vehicle 1) are respectively expressed as L i and W i(See Fig. 1.) The X-axis and Y-axis positions of the center of gravity GC of the sprung mass are L g and W g These parameters (L i , W i , L g , and W g ) are acquired in advance and stored in the storage device of the ECU 10.

number

[0020] By using the detected accelerations Z1'' to Z4'' at the four positions, the vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g " can be calculated with high accuracy.

[0021] Next, the ECU 10 calculates the acceleration in each mode (vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g By integrating the sprung center of gravity position GC, each mode velocity (vertical velocity Z g ', roll speed Φ g ', and pitch speed Θ g ') is calculated. The vertical velocity Z of the center of gravity GC g ', roll speed Φ g ', and pitch speed Θ g ' are expressed by the following formulas (5) to (7), respectively.

number

[0022] Similarly, the ECU 10 controls each mode speed (up and down speed Z g ', roll speed Φ g ', and pitch speed Θ g By integrating the sprung center of gravity GC, each mode displacement (vertical displacement Z g , roll angle (roll angle displacement) Φ g , and pitch angle (pitch angle displacement) Θ g ) is calculated. g (See Fig. 1), roll angle Φ g , and pitch angle Θ g are expressed by the following equations (8) to (10). g The sign of is positive if it is upward and negative if it is downward.

number

[0023] Next, the ECU 10 calculates a vertical demand control amount F for suppressing each mode vibration (vertical vibration, roll vibration, pitch vibration) of the sprung center of gravity position GC. z , the amount of roll control required M r , and the pitch control requirement M p Here, the vertical control amount F z is positive when an upward control force is required. r is positive when a right-downward and left-upward control moment is required. p is taken to be positive when a front down and rear up control moment is desired.

[0024] The ECU 10 calculates these upper and lower required control amounts F z, the amount of roll control required M r , and the pitch control requirement M p The acceleration of each mode (vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g ''), each mode speed (up and down speed Z g ', roll speed Φ g ', and pitch speed Θ g '), and each mode displacement (vertical displacement Z g , roll angle Φ g , and pitch angle Θ g For example, the vertical control amount F z , the amount of roll control required M r , and the pitch control requirement M p are given by the following equations (11) to (13), respectively.

number

[0025] In formulas (11) to (13), G1 z , G2 z , G3 z , G1 r , G2 r , G3 r , G1 p , G2 p , and G3 p is a control gain. In the following description, each control gain will be referred to as control gain G unless a distinction is required.

[0026] As shown by the formulas (11) to (13), the vertical demand control amount F z , the amount of roll control required M r , and the pitch control requirement M p Each of these has a displacement term, a velocity term, and an acceleration term related to the displacement, velocity, and acceleration of the sprung structure 5.

[0027] Specifically, the vertical control amount F z is the vertical displacement Z g and control gain G1 z and the vertical velocity Z g ' and control gain G2 z The velocity term is the product of the vertical acceleration Z g '' and control gain G3 z and an acceleration term which is a product of

[0028] Similarly, the roll request control amount M r is the roll angle Φ g and control gain G1 r and the roll velocity Φ g ' and control gain G2 r and the roll acceleration Φ g '' and control gain G3 r and an acceleration term which is a product of

[0029] Similarly, the pitch control requirement M p is the pitch angle Θ g and control gain G1 p and the pitch velocity Θ g ' and control gain G2 p and the pitch acceleration Θ g '' and control gain G3 p and an acceleration term which is a product of

[0030] Next, the ECU 10 calculates the required control amount F z , M r , and M p is converted (transformed) into a required control amount for the position of each wheel 2 (2FR, 2FL, 2RR, and 2RL). The required control amount for the position of each wheel 2 corresponds to the target control force Fct of the actuator 3A corresponding to each wheel 2.

[0031] The tread width of the front wheel 2F is T f The tread width of the rear wheel 2R is T rThe distance between the front wheel axle and the center of gravity of the spring GC is l f The distance between the rear wheel axle and the center of gravity of the spring GC is l r In this case, the target control force Fct (Fct fr , Fct fl , Fct rr , and Fct rl ) is expressed by the following equation (14).

number

[0032] The ECU 10 calculates the required control amount F at the sprung center of gravity position GC according to the formula (14). z , M r , and M p can be converted into a target control force Fct of each actuator 3A. Alternatively, the ECU 10 converts the required control amount F z , M r , and M p The target control force Fct for each wheel 2 may be calculated by referring to a map based on the above.

[0033] The ECU 10 calculates the required control amount X (here, F z , M r , and M p Specifically, the ECU 10 controls the actuator 3A to generate a control force Fc according to the required controlled variable X(F z , M r , and M p ) after conversion from the target control force Fct (Fct fr , Fct fl , Fct rr , and Fct rl ) to the actuator 3A corresponding to each wheel 2.

[0034] In the example shown in the above formulas (11) to (13), the required control amount X has three terms: a displacement term, a speed term, and an acceleration term. When performing this FB control, instead of such an example, the required control amount X may have only one or two control terms: a displacement term, a speed term, and an acceleration term. Also, as shown in formulas (11) to (13), each control term of the required control amount X is expressed by the product of the sprung state amount Y and a control gain G. For this reason, when the control gain G becomes large, the value (control amount) of the control term having the control gain G, in other words, the control force Fc, becomes large, and as a result, the control effect (vibration damping effect or vibration excitation effect) becomes high.

[0035] In addition, the required control amount X in the FB control of the sprung state amount Y is the required control amount F for suppressing each mode vibration of the sprung center of gravity position GC. z , M r , and M p For example, the sprung state quantity Y (sprung displacement Z s (See Figure 2) and sprung speed Z s ', sprung acceleration Z s '') and the control gain. s The sign of is positive when it is upward and negative when it is downward. In addition, the sprung state quantity Y used in calculating the required control amount X may be an in-phase or out-of-phase component of the sprung state quantity Y at the position of the left and right front wheels 2F or the left and right rear wheels 2R.

[0036] 1-2-2. Issues and solutions for suspension control based on sprung acceleration sensors In the following description, each sprung acceleration sensor 14-i (i=1 to 4) will be referred to as a sprung acceleration sensor (or simply an "acceleration sensor") 14 unless there is a need to particularly distinguish between them.

[0037] 1-2-2-1. Sensor abnormality detection If an abnormality such as a breakdown occurs in the acceleration sensor 14, suspension control will be performed based on erroneous sensor information. As a result, the vehicle body 6 may be significantly vibrated or the vibration damping effect may be reduced. For this reason, it is necessary to quickly detect the abnormality in the acceleration sensor 14.

[0038] Examples of causes of an abnormality in the acceleration sensor 14 include sticking of movable parts inside the sensor, and a break (including an intermittent break) or short in the sensor circuit or signal line. The output value of the acceleration sensor 14 is usually constantly fluctuating while the vehicle is traveling. More specifically, the sensor output signal changes significantly due to various road surface inputs. For this reason, for example, based on the waveform of the sensor output signal (for example, the magnitude of the output signal), it is possible to determine that the sensor output signal is abnormal and that the sprung acceleration Z s In the first place, it is difficult to accurately distinguish whether acceleration sensor 14 is detecting "normally" or not. Furthermore, if an attempt is made to quickly determine an abnormality in acceleration sensor 14, which is difficult to determine accurately, from the waveform of the sensor output signal by simply shortening the determination time, there is a risk of erroneous determination. For example, if an erroneous determination is made that acceleration sensor 14 is abnormal when it is actually normal, suspension control will be stopped excessively, and the vibration damping effect that should have been obtained will not be obtained.

[0039] In view of the above-mentioned problems, in this embodiment, the detected acceleration Z i The processes executed by the ECU 10 in association with the suspension control based on "Abnormality Detection Process" and "Sensor Identification Process" include the following "Abnormality Detection Process" and "Sensor Identification Process". A specific example of these processes will be described using the flowchart shown in FIG. 3, but the outline of these processes is as follows.

[0040] In the abnormality detection process, the ECU 10 detects the accelerations Z i '' based on the estimated acceleration Z of the sprung mass at the position of the remaining one acceleration sensor 14 iestThen, the ECU 10 calculates the calculated estimated acceleration Z iest '' and the detected acceleration Z of the remaining one acceleration sensor 14 i Based on the comparison with "", it is determined whether or not an abnormal acceleration sensor 14 is included among the four acceleration sensors 14.

[0041] The sensor identification process is executed in response to detection by the abnormality detection process of the inclusion of an abnormal acceleration sensor 14. In the sensor identification process, the ECU 10 identifies (determines) as the abnormal acceleration sensor 14 an acceleration sensor whose output signal exhibits abnormal behavior over a predetermined determination time T0 among the four acceleration sensors 14.

[0042] 1-2-2-2. Suspension control when sensor abnormality is detected Of the abnormality detection process and the sensor identification process according to this embodiment, for example, only the abnormality detection process may be executed in association with the suspension control. Then, when it is determined by the abnormality detection process that an abnormal acceleration sensor 14 is included, for example, the suspension control may be stopped. Also, both the abnormality detection process and the sensor identification process may be executed in association with the suspension control. Then, for example, the suspension control may be stopped after the abnormal acceleration sensor 14 has been identified by the sensor identification process.

[0043] In addition, if the suspension control is stopped as described above when a sensor abnormality is detected by executing at least the abnormality detection process out of the abnormality detection process and the sensor identification process, the state of the sprung structure 5 may suddenly change. Therefore, in this embodiment, the processes executed by the ECU 10 include the following "calculation process" and "abnormality control process". Specific examples of these processes will be described using the flowchart shown in FIG. 3, but the outline of these processes is as follows.

[0044] For the sake of convenience, the sprung state quantity calculated using the remaining acceleration sensors 14 excluding the abnormal acceleration sensor 14 under the condition where a sensor abnormality occurs will be referred to as "Ya" and "Xa", respectively. The calculation process is carried out after the abnormal acceleration sensor 14 is identified by the sensor identification process, and the detected acceleration Z i The abnormality control process is a process for controlling the actuator 3A to generate a control force Fc corresponding to a required control amount Xa, which is the product of the sprung state amount Ya calculated by the calculation process and a control gain G.

[0045] 1-2-2-3. Specific examples of processing 3 is a flowchart showing a process related to the suspension control according to the embodiment 1. The process of this flowchart is executed repeatedly while the vehicle 1 is traveling, for example.

[0046] <Step S100> In step S100, the ECU 10 acquires acceleration sensor information of the sprung structure 5. Specifically, as an example of the acceleration sensor information, the ECU 10 acquires the detected accelerations Z i '' to get .

[0047] In addition, the "sprung acceleration sensor" according to the present disclosure detects the acceleration Z i As long as the detected acceleration Z'' can be obtained, the sensor does not necessarily have to be installed on the sprung structure 5 as in the example of the sprung acceleration sensor 14. Specifically, the "sprung acceleration sensor" according to the present disclosure may be configured, for example, by combining a vehicle height sensor that detects the vertical displacement of the vehicle body 6 (sprung structure 5) with an unsprung acceleration sensor. More specifically, the detected acceleration Z i"" may be obtained by calculation based on the detection values ​​of the vehicle height sensor and the unsprung acceleration sensor, or may be obtained by estimation by an observer that uses the detection values ​​of these two sensors. In an example in which a combination of the vehicle height sensor and the unsprung acceleration sensor is used as the sprung acceleration sensor, an abnormality in either or both of the vehicle height sensor and the unsprung acceleration sensor corresponds to an abnormality in the above-mentioned "sprung acceleration sensor."

[0048] <Step S102> Next, in step S102, the ECU 10 calculates the acceleration Z i '', the estimated acceleration Z of the sprung mass at the position of the remaining one acceleration sensor 14 iest In other words, this estimated acceleration Z iest '' corresponds to the estimated sensor value of the remaining acceleration sensor 14. It may be arbitrarily determined which of the four sprung acceleration sensors 14-i is to be used as the "remaining acceleration sensor 14." In the calculation example described below, the acceleration sensor 14-4 (i.e., the acceleration sensor corresponding to the left rear wheel 2RL) is used as the "remaining acceleration sensor 14."

[0049] Specifically, under the condition that the sprung structure 5 is a rigid body, the ECU 10 calculates an estimated acceleration Z of the remaining acceleration sensor 14-4 from the detected accelerations Z1'', Z2'', and Z3'' of the three acceleration sensors 14-1, 14-2, and 14-3 acquired in step S100. 4est In this case, for example, the ECU 10 first calculates the vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g Next, the ECU 10 converts the vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g '' Estimated acceleration Z 4est'' is calculated.

number

[0050] <Step S104> Next, in step S104, the ECU 10 calculates the estimated acceleration Z 4est A filtering process is performed by applying a band pass filter (BPF) to each of detected acceleration (actual sensor value) Z1'' and detected acceleration (actual sensor value) Z2''.

[0051] According to the process of step S102 described above, the sensor value of the remaining acceleration sensor 14 out of the three acceleration sensors 14 is the estimated acceleration Z 4est Therefore, due to the influence of twisting and bending of the vehicle body 6, the estimated acceleration Z 4est In addition, due to the influence of sensor drift, etc., the estimated acceleration Z4'' may deviate from the detected acceleration Z5'' even for low-frequency components. 4est '' discrepancies may occur.

[0052] Therefore, in step S104, the ECU 10 uses a BPF that has a pass band that is less susceptible to these influences (for example, 1 to 5 Hz) as the estimated acceleration Z 4est This is applied to each of detected acceleration Z1 and detected acceleration Z2. This makes it possible to extract frequency band components in which deviation between the two is unlikely to occur, making it possible to perform the next anomaly detection process more accurately.

[0053] <Step S106> The process of step S106 corresponds to an example of the above-mentioned "abnormality detection process." In step S106, the ECU 10 calculates the estimated acceleration Z 4est For comparison with the detected acceleration Z4, the ECU 10 may use, as an example, an estimated acceleration Z 4est The difference between the detected acceleration Z4 and ΔZ (=Z 4est Then, it is determined whether the absolute value of the difference ΔZ is less than a predetermined threshold value TH1.

[0054] Estimated acceleration Z 4est If there is no abnormality in the three acceleration sensors 14-1, 14-2, and 14-3 used in the calculation of the estimated acceleration Z 4est " and detected acceleration Z4" become equal or substantially equal. Therefore, the absolute value of the difference ΔZ becomes small. Therefore, if the absolute value of ΔZ is less than the threshold value TH1 (step S106; Yes), the ECU 10 determines that the four acceleration sensors 14 are normal (in other words, none of the acceleration sensors 14 is abnormal).

[0055] On the other hand, if the absolute value of ΔZ is equal to or greater than the threshold value TH1 (step S106; No), the ECU 10 determines that the four acceleration sensors 14 include an abnormal acceleration sensor 14.

[0056] Now, referring to FIG. 4, the process in step S106 is performed to determine which of the four acceleration sensors 14 is used to estimate the acceleration Z iest Regardless of whether the estimated acceleration Z iest '' and detected acceleration Z i The reason why it is possible to quickly determine that an abnormal acceleration sensor 14 is included among the four acceleration sensors 14 by simply comparing with '' once will be described below.

[0057] 4A to 4D are supplementary diagrams for explaining the abnormality detection process (step S106). More specifically, all of Fig. 4(A) to Fig. 4(D) show an example in which an abnormality (x) has occurred in acceleration sensor 14-3, and the remaining three acceleration sensors 14-1, 14-2, and 14-4 are normal (◯).

[0058] Figure 4(A) shows the estimated acceleration Z iest In this example, the acceleration sensor 14-3 is used as the target for calculating the estimated acceleration Z 3est 4B to 4D, the estimated acceleration Z iest '' is the detected acceleration Z of the acceleration sensor 14 having an abnormality. i '', the detected acceleration Z of the normal acceleration sensor 14 is calculated. i Deviate from ''.

[0059] In this way, by the process of step S106, any acceleration sensor 14 is used to estimate the acceleration Z iest The estimated acceleration Z is used to calculate iest '' and detected acceleration Z i By simply comparing with '' once, it is possible to quickly determine that an abnormal acceleration sensor 14 is included. More specifically, an abnormality can be detected more quickly than when a process for detecting a sensor abnormality based on the presence or absence of abnormal behavior of the output signal of the sprung acceleration sensor is performed alone using a long determination time (e.g., 30 seconds).

[0060] In addition, in step S106, the estimated acceleration Z iest '' and detected acceleration Z i The value used for the comparison with '' is not limited to the simple difference ΔZ described above, as long as it is possible to distinguish (evaluate) the difference between the two values. Specifically, for example, the estimated acceleration Z iest '' and detected acceleration Z iIn order to more sufficiently remove high-frequency noise that may be superimposed on each of the estimated acceleration Z ′′ and the estimated acceleration Z ′′ before comparing the two, a low-pass filter (LPF) may be applied to both. Then, the absolute value of the difference between the two values ​​after the LPF may be used for the comparison. Alternatively, iest '' and detected acceleration Z i Alternatively, the absolute value of the difference between the moving average values ​​of the estimated acceleration Z iest '' and detected acceleration Z i The correlation coefficient for '' may be used for the above comparison.

[0061] <Step S108> As described above, if the determination result in step 106 is Yes (i.e., all four acceleration sensors 14 are normal), the process proceeds to step S108. In step S108, the ECU 10 uses a normal control gain G (hereinafter, for convenience, referred to as a "normal gain Gn") while detecting the acceleration Z detected by the four sprung acceleration sensors 14. i This causes the FB control to continue as normal.

[0062] In addition, the normal gain Gn here is the acceleration Z detected by the sprung acceleration sensor 14. i This is the basic value of the control gain G used in suspension control based on the Skyhook control law. In this example of FB control that uses a required control amount X having three control terms, a proportional term, a speed term, and an acceleration term, the basic value of the control gain G of each of the three control terms, which is set in advance based on the balance between the control terms according to the Skyhook control law, corresponds to the normal gain Gn.

[0063] <Step S110> If the determination result in step 106 is No (that is, if an abnormal acceleration sensor 14 is included), the process proceeds to step S110. The process in step S110 corresponds to an example of the above-mentioned "sensor identification process."

[0064] The sensor identification process is executed for each of the four acceleration sensors 14. In the sensor identification process, the ECU 10 identifies (determines) an acceleration sensor whose output signal shows "abnormal behavior" over a predetermined determination time T0 among the four acceleration sensors 14 as an abnormal acceleration sensor 14. This determination time T0 is, for example, about 10 seconds or 5 seconds with the current time as the end point.

[0065] An example of the "abnormal behavior" of the sensor signal to be determined in the sensor identification process is caused by the sticking of the acceleration sensor 14. Specifically, when the sensor is stuck, the output signal of the acceleration sensor 14 (i.e., the detected acceleration Z i Therefore, in the sensor identification process, the ECU 10 determines whether the time during which the fluctuation range of the output signal of the acceleration sensor 14 is maintained at or below a predetermined threshold value TH2 has exceeded a determination time TO. This threshold value TH2 is determined in advance as a value equivalent to the upper limit of the fluctuation range obtained when the sensor is stuck, for example.

[0066] Another example of the "abnormal behavior" of the sensor signal is caused by a break or short circuit in the acceleration sensor 14. Specifically, when a break occurs in the acceleration sensor 14, the output signal of the acceleration sensor 14 continuously indicates zero. When a short circuit occurs in the acceleration sensor 14, the output signal of the acceleration sensor 14 continuously indicates the same value as the power supply voltage. In this way, when a break or short circuit occurs in the acceleration sensor 14, the acceleration sensor 14 continuously outputs an output signal outside the normal sensor output range. Therefore, in the sensor identification process, the ECU 10 determines whether or not the time during which the acceleration sensor 14 continuously outputs an output signal outside the normal sensor output range exceeds a determination time T0. As a result, the acceleration sensor 14 that continuously outputs an output signal outside the sensor output range for a time exceeding the determination time T0 is determined (identified) to be abnormal.

[0067] In step S110, if an abnormal acceleration sensor 14 is identified (step S110; Yes), the process proceeds to step S112. On the other hand, if an abnormal acceleration sensor 14 is not identified (step S110; No), the process proceeds to step S108 already described.

[0068] In addition, if the absolute value of ΔZ is equal to or greater than the threshold value TH1 in step S106 and the process proceeds to step S110, an abnormal acceleration sensor 14 is basically identified. However, there is a possibility that an erroneous determination is made in step S106, and as a result, although it is exceptional, the process may proceed to step S108 after proceeding to step S110. The process of step S110 also has the significance of serving as a double-check function for detecting an abnormality in the sensor in such exceptional cases. In other words, the sensor identification process can be used to suppress erroneous determination in the abnormality detection process.

[0069] <Step S112> The process of step S112 corresponds to an example of the above-mentioned "calculation process." In step S112, the ECU 10 calculates the detected accelerations Z i The sprung state quantity Ya is calculated based on

[0070] Specifically, for example, when the FB control is executed as the suspension control based on the sprung state quantity Ya, the ECU 10 calculates the sprung state quantity Ya of the acceleration term, the velocity term, and the displacement term. This calculation can be performed, for example, as follows. More specifically, the ECU 10 uses the above equations (16) to (18) to calculate the acceleration Z i Based on the above equations (11) to (13), the acceleration of each mode (vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ gNext, the ECU 10 calculates each modal speed (vertical speed Z g ', roll speed Φ g ', and pitch speed Θ g Similarly, the ECU 10 further integrates each calculated modal speed according to the equations (8) to (10) to calculate each modal displacement (vertical displacement Z g , roll angle Φ g , and pitch angle Θ g ) is calculated.

[0071] <Step S114> The process of step S114 and the subsequent step S116 corresponds to one example of the above-mentioned "abnormality control process". First, in step S114, the ECU 10 sets an abnormality gain Ga smaller than the normal gain Gn. Note that the amount of reduction of the abnormality gain Ga with respect to the normal gain Gn is determined in advance.

[0072] Here, in the example of FB control having a displacement term, a velocity term, and an acceleration term, it is the acceleration term that has a particularly large effect on the stability of the FB control. Therefore, in step S114, the change to the abnormality gain Ga is performed focusing on the acceleration term that has a particularly large effect on the stability of the FB control. Specifically, at least the control gain G of the acceleration term among the three control terms is changed to the abnormality gain Ga. For example, only the control gain G of the acceleration term is changed to the abnormality gain Ga. Alternatively, the control gain G of one or both of the displacement term and the velocity term may be changed to the abnormality gain Ga together with the acceleration term. Note that, when the control gain G of multiple control terms is changed, the amount of decrease of the abnormality gain Ga with respect to the normal gain Gn may be determined in advance for each control term. For example, when all the control gains G of the three control terms are reduced, the amount of decrease of the control gain G of the acceleration term may be increased more than the amount of decrease of at least one of the control gains G of the displacement term and the velocity term.

[0073] <Step S116> Next, in step S116, the ECU 10 uses the abnormality gain Ga set in step S114 and calculates the accelerations Z detected by the three normal sprung acceleration sensors 14. i In more detail, the ECU 10 controls the actuator 3A to generate the control force Fc corresponding to the required control amount Xa, which is the product of the sprung state amount Ya and the abnormality-state gain Ga calculated in step S112.

[0074] 1-3.Effects As described above, according to the first embodiment, the detected acceleration Z i The above-mentioned abnormality detection process is executed as a process related to suspension control based on ". As already explained with reference to FIG. 4, this abnormality detection process makes it possible to quickly determine whether an abnormal acceleration sensor 14 is included among the four acceleration sensors 14. As a result, when the abnormality detection process is executed prior to the start of suspension control, it is possible to quickly determine that all four acceleration sensors 14 are normal, and the control start timing can be advanced. Furthermore, when the abnormality detection process is executed constantly or periodically while suspension control is being executed, it becomes possible to quickly start measures (such as continuing control using abnormality control process or stopping control) in response to the detection of a sensor abnormality.

[0075] In addition, in the sensor abnormality detection according to the first embodiment, the above-mentioned sensor identification process is executed together with the abnormality detection process. That is, the sensor identification process is executed under a situation where it is determined by the abnormality detection process that an abnormal acceleration sensor 14 is included among the four acceleration sensors 14. By performing the determination in two stages in this way, it becomes possible to identify the abnormal acceleration sensor 14 while shortening the determination time T0 used in the sensor identification process compared to the case where only the sensor identification process is executed without the abnormality detection process. Specifically, for example, in the case where a determination time T0 of, for example, 30 seconds is required for accurate determination in the example of only the sensor identification process, the determination time T0 can be shortened to, for example, 10 seconds or 5 seconds by this two-stage determination. As described above, the abnormal acceleration sensor 14 can be quickly identified by the combination of the abnormality detection process and the sensor identification process.

[0076] Furthermore, according to the first embodiment, after the abnormal acceleration sensor 14 is identified by the sensor identification process, the above-mentioned calculation process and abnormality control process are executed. i It becomes possible to continue suspension control by calculating (estimating) the sprung state quantity Ya based on ''. More specifically, compared to the case where the acceleration detected by the abnormal acceleration sensor 14 is continued after the occurrence of an abnormality, it is possible to prevent vibration of the sprung structure 5 (vehicle body 6) caused by the sensor abnormality. Also, by continuing suspension control using the remaining normal acceleration sensor 14, it is possible to ensure the comfort of the vehicle 1 and the stability of the suspension control even when an abnormality is detected.

[0077] Furthermore, according to the abnormality control process, an abnormality gain Ga that is smaller than the normal gain Gn that is used when the four acceleration sensors 14 are normal is used. In this way, by reducing the required control amount Xa using the abnormality gain Ga when a sensor abnormality is detected, it is possible to suppress an uncomfortable feeling in control that may occur when suspension control is continued using a smaller number of acceleration sensors 14 than normal. More specifically, it is possible to more suitably maintain the stability of suspension control under a situation where a smaller number of acceleration sensors 14 than normal is used.

[0078] As already explained, in the example of FB control having a displacement term, a speed term, and an acceleration term, the change to the abnormality gain Ga may be made by focusing on the acceleration term, which has a particularly large effect on the stability of the FB control. Here, since reducing the control gain G may lead to a decrease in the vibration suppression effect of this FB control, it is desirable to keep the change to the abnormality gain Ga to a minimum necessary to ensure the stability of the FB control. Therefore, by changing only the control gain G of the acceleration term to the abnormality gain Ga, the control stability may be ensured while suppressing the decrease in the vibration suppression effect. Alternatively, for the same purpose, the change to the abnormality gain Ga may be made to only the acceleration term and either the displacement term or the speed term, rather than all three control terms.

[0079] 1-4.Modifications In the above-described first embodiment, the vehicle 1 is illustrated as having four sprung acceleration sensors 14. However, the "abnormality detection process" described in the first embodiment may be applied to a vehicle having five or more sprung acceleration sensors 14. In the example in which five or more sprung acceleration sensors 14 are included, the location of the one or more sprung acceleration sensors 14 added to the four sprung acceleration sensors 14-1, 14-2, 14-3, and 14-4 is not particularly limited.

[0080] For example, in an example in which five sprung acceleration sensors 14 are provided, the "abnormality detection process" is executed as follows. That is, in accordance with the above formulas (1) to (4), the vertical acceleration Zg '', roll acceleration Φ g '', and pitch acceleration Θ g '' is calculated. Next, an estimated acceleration at the position of the remaining acceleration sensor 14 is calculated using an equation similar to the above equation (19). The calculated estimated acceleration is then compared with the detected acceleration of the remaining acceleration sensor 14. As a result, it can be determined that an abnormal acceleration sensor 14 is included, similar to the example including four acceleration sensors 14.

[0081] Also, the "sensor identification process" in a vehicle equipped with, for example, five sprung acceleration sensors 14 can be performed using the same method (first method) as the process in step S110 described above. Also, in an example equipped with five or more sprung acceleration sensors 14, the sensor identification process may be performed using, for example, the following second method.

[0082] In the second method, for example, in the case of a vehicle equipped with five sprung acceleration sensors 14, the above formulas (15) to (19) are used to calculate an estimated acceleration of one of the remaining two acceleration sensors 14 from the detected acceleration of the three acceleration sensors 14, and the process is executed multiple times while sequentially changing the combination of the three acceleration sensors 14 used for the estimated acceleration and the acceleration sensor 14 that is the target of the calculation of the estimated acceleration. As a result, if the estimated acceleration and the detected acceleration of the acceleration sensor 14 that is the target of the calculation of the estimated acceleration are equal or substantially equal, it is found that the four acceleration sensors 14 that are the targets of the comparison are normal. Therefore, by executing such a process multiple times, it is possible to identify an abnormal acceleration sensor 14. More specifically, in an example configuration including the four acceleration sensors 14-1 to 14-4 shown in FIG. 1 and the acceleration sensor 14-g arranged at the sprung center of gravity position GC, if the estimated acceleration at the sprung center of gravity position GC based on the three acceleration sensors 14-1, 14-2, and 14-3 is equal or substantially equal to the detected acceleration of the acceleration sensor 14-g, it can be determined that the remaining acceleration sensor 14-4 is abnormal.

[0083] In addition, in an example having five or more sprung acceleration sensors 14, if there are four or more wheels 2 corresponding to acceleration sensors 14 that are not abnormal, the following technique can be used to calculate the sprung state quantity Ya used for suspension control while reducing the influence of torsion of the sprung structure 5 (vehicle body 6). Details of this technique are described in JP 2019-010912 A. The outline of this technique is as follows.

[0084] That is, according to the above technique, first, the acceleration in each mode (vertical acceleration Z g '', roll acceleration Φ g '', and pitch acceleration Θ g Then, according to the technology, under the condition that the sprung structure 5 is a rigid body, the acceleration of each mode at the sprung center of gravity position GC is calculated as the sprung acceleration (vertical acceleration) Z s1 ''~Z s4 This conversion can be performed, for example, using the following formula (20):

number

[0085] By using the above-mentioned technology, the effect of torsional vibration is reduced. si '' is obtained. The vertical acceleration Z si By using the sprung state variable Ya for suspension control, it is possible to improve the stability of suspension control and to increase the vibration damping effect by using a large control gain G, compared to the case where the influence of the torsion is not eliminated. This is convenient for continuing suspension control in an appropriate manner under a situation where a smaller number of acceleration sensors 14 are used compared to normal times due to detection of a sensor abnormality. In addition, by taking into account the influence of bending of the sprung structure 5 (vehicle body 6), the vertical acceleration Z siIf a sufficient number of acceleration sensors 14 remain to calculate the vertical acceleration Z ′′ when a sensor abnormality is detected, a known method is used to reduce the influence of the bending. si Calculation of "" may be performed.

[0086] 2. Second embodiment The second embodiment differs from the first embodiment in the method of detecting an abnormality in a sensor. Specifically, in the second embodiment, the following "sensor identification process" is executed to detect an abnormality in a sensor.

[0087] 5 is a supplementary diagram for explaining the sensor identification process according to the second embodiment. In the sensor identification process of the present embodiment, the ECU 10 detects the accelerations Z i Based on this, a "specific value SV" is calculated which is a related value of the vertical displacement (heave) Z, roll angle Φ, or pitch angle Θ at the same position on the sprung structure 5. The "same position" here is, for example, the sprung center of gravity position GC, but it may be any position on the sprung structure 5 other than the sprung center of gravity position GC. Furthermore, the related value of the vertical displacement Z, roll angle Φ, or pitch angle Θ here may not only be the vertical displacement Z, roll angle Φ, or pitch angle Θ itself, but may also be, for example, the vertical velocity Z', roll velocity Φ', pitch velocity Θ', vertical acceleration Z'', roll acceleration Φ'', or pitch acceleration Θ''.

[0088] The ECU 10 calculates the specific value SV for each of four different combinations of the three acceleration sensors 14. Specifically, in the example of the vehicle 1 equipped with the four acceleration sensors 14, there are four different combinations of the three acceleration sensors 14, combinations A to D, as shown in Fig. 5. The table shown in Fig. 5(B) shows the breakdown of the four combinations A to D of the three acceleration sensors 14 shown in Fig. 5(A) using the numbers i (i=1 to 4) of the wheels 2.

[0089] In the sensor identification process, the ECU 10 identifies an abnormal acceleration sensor 14 from among the four acceleration sensors 14 based on a comparison of the specific values ​​SV among the four different combinations A to D.

[0090] Specifically, if all four acceleration sensors 14 are normal, the specific values ​​SV calculated using each of the combinations A to D will be equal or substantially equal. Therefore, if the specific values ​​SV calculated using each of the combinations A to D are all within the predetermined range Rth, it can be determined that all four acceleration sensors 14 are normal.

[0091] On the other hand, if an abnormality occurs in any one of the four acceleration sensors 14, a difference exceeding the predetermined range Rth will be observed in the specific value SV among the combinations A to D. Specifically, for example, if an abnormality occurs in the acceleration sensor 14-1 with the sensor number i=1, the specific value SV A , S.V. B , and S.V. C For the combination D that does not include the acceleration sensor 14-1, the specific value SV D Therefore, for example, the specific value SV A-C and specific value SV D When the absolute value of the difference ΔSV between the specific value SV and the acceleration sensor 14-1 is equal to or greater than a predetermined threshold value TH2, it can be determined that an abnormality has occurred in the acceleration sensor 14-1. A-C and specific value SV D The value used for the comparison with is not limited to the above-mentioned simple difference ΔSV, as long as it is a method capable of determining (evaluating) the difference between the two values. That is, similar to the example of the processing of step S106 described above, for example, the absolute value of the difference between the two values ​​after the LPF, the absolute value of the difference between the moving average values ​​of the two, or the correlation coefficient related to the two may be used for the comparison.

[0092] Based on the same concept, the occurrence of an abnormality in the acceleration sensor 14-2 with the sensor number i=2 is detected by the specific value SV Cis the specific value SV of the remaining combinations A, B, and D A , S.V. B , and S.V. D In addition, the occurrence of an abnormality in the acceleration sensor 14-3 with the sensor number i=3 can be determined by noting the deviation from the specific value SV B Furthermore, the occurrence of an abnormality in the acceleration sensor 14-4 with the sensor number i=4 can be judged by noting that the specific value SV A This can be determined by noting that it deviates from the others.

[0093] As described above, according to the sensor identification process of the second embodiment, by calculating the specific value SV for each of the four combinations A to D and comparing the specific values ​​SV between the combinations A to D, it is possible to quickly determine whether the four acceleration sensors 14 are normal or not and quickly identify one abnormal acceleration sensor 14 that may be included among the four acceleration sensors 14. More specifically, an abnormality can be detected more quickly than when the process of detecting a sensor abnormality based on the presence or absence of abnormal behavior of the output signal of the sprung acceleration sensor is performed alone using a long determination time (e.g., 30 seconds).

[0094] 6 is a flowchart showing a process related to suspension control according to embodiment 2. The process of this flowchart is executed repeatedly, for example, while the vehicle 1 is traveling. Note that the description of the process of the same steps as those shown in the flowchart shown in FIG. 3 will be omitted or simplified.

[0095] In FIG. 6, in step S200 following step S100, the ECU 10 calculates the specific values ​​SV (SV A ~SV D The specific value SV can be calculated, for example, by using the above formula (15) and any one of formulas (16) to (18).

[0096] Next, in order to perform the sensor identification process more accurately, in step S202, the ECU 10 applies a BPF to each identification value SV calculated in step S200 based on the same concept as in step S104 described above.

[0097] The process of the next step S204 corresponds to an example of the above-mentioned "sensor identification process." In step S204, the ECU 10 compares the specific values ​​SV among the four combinations A to D as already described, thereby determining whether or not there is an abnormal acceleration sensor 14, and identifying the abnormal acceleration sensor 14 if there is an abnormal acceleration sensor 14.

[0098] As a result, if all four acceleration sensors 14 are normal (step S204; No), the process proceeds to step S108. On the other hand, if an abnormal acceleration sensor 14 is present and the abnormal acceleration sensor 14 is identified (step S204; Yes), the process proceeds to step S112.

[0099] Additionally, the "sensor identification process" described in the second embodiment as above may be applied to a vehicle equipped with five or more acceleration sensors 14, instead of the example of four acceleration sensors 14. Specifically, in the example of a vehicle equipped with five acceleration sensors 14, for example, the calculation of the "specific value SV" based on the detected acceleration of four of the five acceleration sensors 14 may be performed for each of five different combinations of the four acceleration sensors 14. Then, based on the same idea as in the example of the vehicle 1 equipped with the four acceleration sensors 14 described above, an abnormal acceleration sensor 14 may be identified from among the five acceleration sensors 14 based on a comparison of the specific values ​​SV among the five different combinations.

[0100] 3. Third embodiment The third embodiment differs from the first and second embodiments in the method of detecting an abnormality in a sensor. Specifically, the third embodiment executes the following "abnormality detection process" and "sensor identification process" to detect an abnormality in a sensor.

[0101] Fig. 7 is a diagram illustrating an example of a configuration of a vehicle 7 according to embodiment 3. Vehicle 7 is configured similarly to vehicle 1 illustrated in Fig. 1, except that vehicle 7 is additionally provided with a gyro sensor 8.

[0102] The gyro sensor 8 is attached to the sprung structure 5 (vehicle body 6) and detects the angular velocity of the sprung structure 5. Specifically, this angular velocity is, for example, the roll velocity Φ' or the pitch velocity Θ' of the sprung structure 5.

[0103] In the “abnormality detection process” according to the present embodiment, the ECU 10 detects the accelerations Z i '', a first estimated angular velocity ω gyest 1. Then, the ECU 10 calculates the calculated first estimated angular velocity ω gyest 1 and the detected angular velocity ω of the gyro sensor 8 gy Based on the comparison, it is determined whether or not an abnormal acceleration sensor 14 is included among the four acceleration sensors 14. Note that the first estimated angular velocity ω gyest 1 is an example of a "first estimated angular velocity related value of the sprung structure at the position of the gyro sensor" according to the present disclosure. The "first estimated angular velocity related value" may be, for example, a first estimated acceleration or a first estimated angle that is an estimated value of the angular acceleration or angle, respectively, of the sprung structure 5 at the position of the gyro sensor 8. Similarly, the detected angular velocity ω gy is an example of a "detected angular velocity related value of the gyro sensor" according to the present disclosure. The "detected angular velocity related value" is, for example, a detected angular velocity ω gy The detected angular acceleration may be a time differential value of ω gy Alternatively, the detection angle may be a time integral value of

[0104] Specifically, if all four acceleration sensors 14 are normal, the detected accelerations Z i First estimated angular velocity ω based on gyest 1 denotes the detected angular velocity ω of the gyro sensor 8 gyOn the other hand, when an abnormality occurs in any of the four acceleration sensors 14, the first estimated angular velocity ω gyest 1 is the detected angular velocity ω gy Therefore, according to the present abnormality detection process, the first estimated angular velocity ω gyest 1 and the detected angular velocity ω gy Based on the comparison with the above, it is possible to quickly determine whether or not an abnormal acceleration sensor 14 is included. More specifically, an abnormality can be detected more quickly than when a process for detecting a sensor abnormality based on the presence or absence of abnormal behavior of the output signal of the sprung acceleration sensor is performed alone using a long determination time (e.g., 30 seconds).

[0105] Moreover, the "sensor identification process" according to this embodiment includes the following first and second examples. Specifically, the first example of the sensor identification process is the same as the sensor identification process (see step S110) described in the first embodiment.

[0106] Next, a second example of the sensor identification process will be described. In the second example, the ECU 10 executes the following process after detecting that an abnormal acceleration sensor 14 is included in the vehicle 7 by the abnormality detection process. That is, the ECU 10 executes the following process after detecting the detected acceleration Z i '', a second estimated angular velocity ω gyest 2. Note that the second estimated angular velocity ω gyest 2 is an example of a “second estimated angular velocity related value of the sprung structure at the position of the gyro sensor” according to the present disclosure. The “second estimated angular velocity related value” may be, for example, a second estimated acceleration or a second estimated angle that is an estimated value of the angular acceleration or angle, respectively, of the sprung structure 5 at the position of the gyro sensor 8.

[0107] Then, the ECU 10 calculates the second estimated angular velocity ω gyest 2 and the detected angular velocity ω gy The combination of the three acceleration sensors 14 is changed while the second estimated angular velocity ω is calculated until the first estimated angular velocity ω is equal to or substantially equal to the second estimated angular velocity ω. gyestThe calculation of 2 is repeated as many times as necessary. As a result, the calculated second estimated angular velocity ω gyest 2 and the detected angular velocity ω gy When the second estimated angular velocity ω becomes equal to or substantially equal to the first estimated angular velocity ω, the ECU 10 calculates the second estimated angular velocity ω gyest The remaining one sprung acceleration sensor 14 that has not been used in the calculation of (2) is identified (confirmed) as the abnormal acceleration sensor 14.

[0108] Specifically, in the second example, the first second estimated angular velocity ω is calculated using, for example, three acceleration sensors 14-1, 14-2, and 14-3. gyest When ω2 is calculated, this second estimated angular velocity ω gyest 2 and the detected angular velocity ω gy If the first second estimated angular velocity ω is equal to or substantially equal to the second estimated angular velocity ω, the remaining acceleration sensor 14-4 is determined to be abnormal. gyest 2 is the detected angular velocity ω gy When the second estimated angular velocity ω 1 deviates from the first estimated angular velocity ω 2 , it can be determined that one of the three acceleration sensors 14-1, 14-2, and 14-3 is abnormal. gyest 2 is calculated. gyest 2 and the second estimated angular velocity ω gyest 2 and the detected angular velocity ω gy By repeating the comparison with the acceleration sensor 14 a required number of times (that is, as necessary), an abnormal acceleration sensor 14 can be identified.

[0109] 8 is a flowchart showing a process related to suspension control according to embodiment 3. The process of this flowchart is executed repeatedly, for example, while the vehicle 1 is traveling. Note that the description of the process of the same steps as those shown in the flowchart shown in FIG. 3 will be omitted or simplified.

[0110] In FIG. 8, in step S300 following step S100, the ECU 10 calculates the detected angular velocity ω gy Get the.

[0111] Next, in step S302, the ECU 10 calculates the accelerations Z i First estimated angular velocity ω based on gyest In an example where the angular velocity of the gyro sensor 8 is the roll velocity Φ′, the first estimated angular velocity ω gyest The calculation of the first estimated angular velocity ω1 can be performed, for example, by changing the position of the calculation target from the sprung center of gravity position GC to the position of the gyro sensor 8, using the above formulas (1), (3), and (6). gyest The calculation of 1 can be performed in a similar manner using the above formulas (1), (4), and (7).

[0112] The detected angular velocity ω obtained in steps S300 and S302 gy and the first estimated angular velocity ω gyest 1, the BPF may be applied in the same manner as in the process of step S104.

[0113] The process of the next step S304 corresponds to an example of the above-mentioned "abnormality detection process." In step S304, the ECU 10 calculates the first estimated angular velocity ω gyest 1 and the detected angular velocity ω gy Based on the comparison, it is determined whether or not an abnormal acceleration sensor 14 is included among the four acceleration sensors 14. If the result of this determination is No, the process proceeds to step S108, and if the result of this determination is Yes, the process proceeds to step S306.

[0114] The process of step S306 corresponds to an example of the above-mentioned "sensor identification process." As already explained, either the first example or the second example may be used as the sensor identification process. As a result, if an abnormal acceleration sensor 14 is identified (step S306; Yes), the process proceeds to step S112. On the other hand, if an abnormal acceleration sensor 14 is not identified (step S306; No), the process proceeds to step S108.

[0115] In addition, the "abnormality detection process" described in the third embodiment as above may be applied to a vehicle equipped with five or more acceleration sensors 14, instead of the example of four acceleration sensors 14. Specifically, based on the same concept as the above example, in the example of a vehicle equipped with five acceleration sensors 14, for example, the detected accelerations Z i The first estimated angular velocity ω gyest 1" and detected angular velocity ω gy may be compared to detect the inclusion of an abnormal acceleration sensor 14.

[0116] Furthermore, the second example of the "sensor identification process" described in the third embodiment may be applied to a vehicle equipped with five or more acceleration sensors 14, instead of the four acceleration sensors 14. Specifically, based on the same concept as the above example, in the example of a vehicle equipped with five acceleration sensors 14, the detected accelerations Z i The second estimated angular velocity ω based on gyest 2 and the detected angular velocity ω gy may be compared to identify an abnormal acceleration sensor 14.

[0117] (Reference example) In a vehicle having at least four sprung acceleration sensors, there is a possibility that an abnormality occurs in a plurality of the sprung acceleration sensors. In an example in which the number of remaining normal sprung acceleration sensors is four, the sprung state quantity Ya used in suspension control (for example, the above-mentioned FB control) can be calculated while eliminating the influence of torsion of the sprung structure 5 (vehicle body 6) by using, for example, the technique described with reference to the formula (20). In an example in which the number of remaining normal sprung acceleration sensors is three, the sprung state quantity Ya can be calculated by the process of step S112 (for example, see FIG. 3). On the other hand, it is also assumed that the number of remaining normal sprung acceleration sensors will be two or one.

[0118] The number of remaining normal sprung acceleration sensors can be determined to be two or one by, for example, executing the sensor identification process described in step S100 alone. If the number of remaining normal sprung acceleration sensors is two or one, the suspension control may be continued, for example, by the following method. That is, for example, in a configuration example in which the remaining two or one normal sprung acceleration sensor is attached to a position (for example, a suspension tower) sufficiently close to the wheel, the suspension control (for example, the above-mentioned FB control) based on the sprung state quantity based on the acceleration detected by the remaining normal acceleration sensor may be executed on a wheel-by-wheel basis for only the wheel corresponding to the acceleration sensor.

[0119] On the other hand, even if it is difficult to calculate the sprung state quantity in an example where the number of remaining normal sprung acceleration sensors is two or one, if the vehicle is equipped with a vehicle height sensor or a stroke sensor, suspension control may be continued for each wheel as follows: That is, instead of FB control based on the sprung state quantity, the suspension actuator may be controlled to generate a control force Fc corresponding to a required control quantity obtained by multiplying the suspension stroke speed obtained from the vehicle height sensor or the stroke sensor by a control gain. This enables suspension control simulating a damper (shock absorber) in a situation where the sprung acceleration sensor cannot be used satisfactorily due to the occurrence of an abnormality, and makes it possible to ensure the stability of the vehicle behavior. [Explanation of symbols]

[0120] 1, 7 cars 2 wheels 3. Suspension 3A Suspension Actuator 4. Unsprung structure 5. Upper sprung structure 6. Body 8 Gyro sensor 10 Electronic Control Unit (ECU) 12 Sensors 14 Spring acceleration sensor

Claims

1. an actuator that applies a vertical control force between an unsprung structure and a sprung structure of the vehicle; At least four sprung acceleration sensors for detecting vertical acceleration of the sprung structure; an electronic control unit that controls the actuator based on the acceleration detected by the at least four sprung acceleration sensors; A vehicle suspension control device comprising: The electronic control unit executes a sensor identification process, In the sensor identification process, the electronic control unit: Calculating a specific value that is a related value of a vertical displacement, a roll angle, or a pitch angle at the same position of the sprung structure based on the detected accelerations of the sprung acceleration sensors that are one less than all of the at least four sprung acceleration sensors, for each of a plurality of different combinations of the sprung acceleration sensors that are one less than all of the at least four sprung acceleration sensors; Identifying an abnormal sprung acceleration sensor from among the at least four sprung acceleration sensors based on a comparison of the specific values ​​among the plurality of different combinations. A vehicle suspension control device comprising:

2. an actuator that applies a vertical control force between an unsprung structure and a sprung structure of the vehicle; At least four sprung acceleration sensors for detecting vertical acceleration of the sprung structure; A gyro sensor for detecting an angular velocity of the sprung structure; an electronic control unit that controls the actuator based on the acceleration detected by the at least four sprung acceleration sensors; A vehicle suspension control device comprising: The electronic control unit executes an abnormality detection process, In the abnormality detection process, the electronic control unit Calculating a first estimated angular velocity related value of the sprung structure relative to a position of the gyro sensor based on the accelerations detected by all of the at least four sprung acceleration sensors; Based on a comparison between the calculated first estimated angular velocity-related value and the detected angular velocity-related value of the gyro sensor, it is determined whether or not an abnormal sprung acceleration sensor is included among the at least four sprung acceleration sensors. A vehicle suspension control device comprising:

3. After determining that an abnormal sprung acceleration sensor is included by the abnormality detection process, the electronic control unit executes a sensor identification process to identify, among the at least four sprung acceleration sensors, a sprung acceleration sensor whose output signal shows abnormal behavior for a predetermined determination time as the abnormal sprung acceleration sensor.

3. The vehicle suspension control device according to claim 2.

4. The electronic control unit executes a sensor identification process after determining that an abnormal sprung acceleration sensor is included by the abnormality detection process, In the sensor identification process, the electronic control unit: calculating a second estimated angular velocity related value of the sprung structure relative to the position of the gyro sensor based on accelerations detected by the sprung acceleration sensors, the number of which is one less than all of the at least four sprung acceleration sensors; Repeating the calculation of the second estimated angular velocity related value a necessary number of times while changing the combination of the sprung acceleration sensors, the number of which is one less than all of the sprung acceleration sensors, until the calculated second estimated angular velocity related value and the detected angular velocity related value of the gyro sensor become equal or substantially equal to each other; When the calculated second estimated angular velocity related value and the detected angular velocity related value of the gyro sensor are equal or substantially equal, one remaining sprung acceleration sensor that has not been used in the latest calculation of the second estimated angular velocity related value is identified as the abnormal sprung acceleration sensor.

3. The vehicle suspension control device according to claim 2.

5. The electronic control unit includes: a calculation process for calculating a sprung state quantity based on the detected accelerations of the remaining sprung acceleration sensors excluding the identified abnormal sprung acceleration sensor after the abnormal sprung acceleration sensor is identified by the sensor identification process; an abnormality control process for controlling the actuator so as to generate the control force corresponding to a required control amount, which is a product of the calculated sprung state amount and a control gain; Run 5. A vehicle suspension control device according to claim 1, 3 or 4.

6. In the abnormality control process, the electronic control unit reduces the control gain compared to when all of the at least four sprung acceleration sensors are normal.

6. The vehicle suspension control device according to claim 5.

7. The required control amount is required to reduce vibration of the sprung structure, and includes at least one of the displacement term and the velocity term and the acceleration term among a displacement term, a velocity term, and an acceleration term related to a displacement, a velocity, and an acceleration term of the sprung structure, In the abnormality control process, the electronic control unit reduces only the control gain of the acceleration term.

7. The vehicle suspension control device according to claim 6.

Images