JP5747617B2 - Car body tilt control device, car body tilt control method - Google Patents

Description

  The present invention relates to a vehicle body tilt control device and a vehicle body tilt control method.

  Conventionally, there has been a proposal to introduce a tiltable vehicle structure from the viewpoint of improving the stability of a vehicle and applying it to a driving utilizing a vehicle dynamics model in a scene such as turning. For example, in the prior art of Patent Document 1, the influence of the lateral acceleration on the driver is reduced by inclining the vehicle body according to the lateral acceleration during turning.

JP 2005-231415 A

However, since the wheel load fluctuates transiently when the vehicle body is tilted, for example, the tire grounding property on one side is lowered, which may affect the vehicle stability during turning.
An object of the present invention is to compensate for wheel load fluctuations when the vehicle body is tilted, and to further improve stability during turning.

In order to solve the above problems, an actuator for tilting the vehicle body in the roll direction is provided, and a target tilt angle for tilting the vehicle body in the roll direction on the inside of the turn is calculated according to the turning state of the vehicle. Then, the left and right wheel load fluctuations are estimated according to the turning state of the vehicle and the target inclination angle, and the left and right wheels are supported on either the left or right wheel when the left and right wheel loads fluctuate according to the turning state of the vehicle. The limit value correction amount for the physical limit wheel load, which is the load when the entire load of the load to be loaded, is calculated. Then, the control limit wheel load is calculated by subtracting the limit value correction amount from the physical limit wheel load, and the target inclination angle is limited so that the left and right wheel load fluctuations do not exceed the control limit wheel load. The actuator is driven and controlled according to the target inclination angle subjected to the restriction process.

  According to the apparatus of the present invention, while estimating the left and right wheel load fluctuations, the control limit wheel load is set from the limit value correction amount, and the left and right wheel load fluctuations are predicted so as not to exceed the control limit wheel load. Since the target inclination angle is limited, the wheel load fluctuation can be compensated for even if there is a parameter fluctuation or modeling error. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

It is a schematic diagram of vehicle body tilting. It is the schematic of a suspension structure. It is a system configuration diagram. It is a functional block diagram which shows a vehicle body tilt control process. It is a flowchart which shows a left-right wheel load fluctuation | variation estimation process. It is a flowchart which shows a limit value correction amount calculation process. It is a flowchart which shows an inclination angle restriction | limiting process. It is a conceptual diagram of the limit wheel load for control. It is a time chart which shows an effect. It is a system configuration figure showing a second embodiment. It is a flowchart which shows the limit value correction amount calculation process of 3rd embodiment. It is a conceptual diagram which shows the limit value correction amount calculation process of 3rd embodiment. It is a flowchart which shows the limit value correction amount calculation process of 4th embodiment. It is a conceptual diagram which shows the limit value correction amount calculation process of 4th embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
<< First embodiment >>
"Constitution"
FIG. 1 is a schematic diagram of vehicle body tilting.
A vehicle body 2 is suspended from the wheel 1 via a suspension, and the suspension can tilt the vehicle body 2 by driving a drive motor 3. For example, the vehicle body 2 is tilted inward during turning.

FIG. 2 is a schematic view of the suspension structure.
Since the suspension structure of the left and right wheels is the same structure that is bilaterally symmetrical, only the left wheel side will be described here. This suspension is a double wishbone suspension, and a knuckle (upright) 11 that supports the wheel 1 is swingable via an upper link 12 and a lower link 13 on the vehicle body frame 14. It is connected to.

The upper link 12 is composed of an A arm, and each of the wheel side attachment point and the vehicle body side attachment point is connected to the knuckle 11 and the vehicle body frame 14 via a rubber bush. The lower link 13 is also composed of an A arm, and each of the wheel side mounting point and the vehicle body side mounting point is connected to the knuckle 11 and the vehicle body frame 14 via a rubber bush.
A lean arm 15 having a pivot shaft in the longitudinal direction of the vehicle body and projecting evenly toward the left and right sides is pivotally supported at the center position in the vehicle width direction of the vehicle body frame 14. A shock absorber 16 and a coil spring 17 are interposed between the tip of the lean arm 15 and the lower link 13. Further, the drive motor 3 is connected to the rotation shaft of the lean arm 15 via a reduction gear (not shown).

  Therefore, when the drive motor 3 is rotated, the lean arm 15 is rotated with respect to the vehicle body frame 14 and the left end and the right end of the lean arm 15 are displaced in the vertical direction. 13 swings. When the left end is lowered, the right end of the lean arm 15 is raised, and when the left end is raised, the right end is lowered, so that the left and right wheels have reverse suspension strokes.

  That is, when the drive motor 3 is rotated clockwise in front view of the vehicle, the left wheel side becomes a rebound stroke and the right wheel side becomes a bound stroke due to the rotation of the lean arm 15 (tilting that lowers the left side). At this time, a force in the rebound direction that pushes down the lower link 13 acts on the left wheel side, and the left side of the vehicle body 2 is lifted by the reaction force received from the left wheel, and as a result, the vehicle body 2 tilts to the right side.

  Conversely, when the drive motor 3 is rotated counterclockwise when viewed from the front of the vehicle, the left wheel side becomes a bound stroke and the right wheel side becomes a rebound stroke due to the rotation of the lean arm 15 (tilting to lower the right side). At this time, a force in the rebound direction that pushes down the lower link 13 acts on the right wheel side, and the right side of the vehicle body 2 is lifted by the reaction force received from the right wheel, and as a result, the vehicle body 2 tilts to the left side.

The suspension structure described above is provided on the front wheel and the rear wheel, and each is driven and controlled by an individual drive motor 3.
Although the drive motor 3 is used as an actuator for rotating the lean arm 15, other actuators using hydraulic pressure or air pressure may be used. Further, the vehicle body may be tilted by stroking the left and right suspensions in opposite directions with, for example, an electromagnetic shock absorber or the like capable of generating thrust in the expansion and contraction direction.

FIG. 3 is a system configuration diagram.
In addition to the drive motor 3 described above, the vehicle 20 includes a steering angle sensor 21, a yaw rate sensor 22, a lateral acceleration sensor 23, a wheel speed sensor 24, a slip angle sensor 25, and a vehicle control controller 26.
The steering angle sensor 21 detects the steering angle of the steering of the vehicle 20 and inputs the detected value to the vehicle controller 26. The yaw rate sensor 22 detects the yaw rate generated in the vehicle 20 and inputs the detected value to the vehicle controller 26. The lateral acceleration sensor 23 detects the lateral acceleration generated in the vehicle 20 and inputs the detected value to the vehicle control controller 26. The wheel speed sensor 24 detects the rotational speed (wheel speed) of each wheel of the vehicle 20 and inputs the detected value to the vehicle controller 26. The slip angle sensor 25 detects the slip angle of the vehicle 20 and inputs the detected value to the vehicle controller 26.

The vehicle controller 26 executes the vehicle body tilt control process, and drives the drive motor 3 according to the current command value, thereby realizing the tilt operation of the vehicle body 2.
The vehicle controller 26 is configured by a microcomputer and controls the operation of the drive motor 3 based on information input from the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, the wheel speed sensor 24, and the slip angle sensor 25. At the same time, the control operation is canceled.

Next, the vehicle body tilt control process executed by the vehicle controller 26 will be described.
FIG. 4 is a functional block diagram showing the vehicle body tilt control process.
The vehicle controller 26 includes a turning state detection unit 41, a target inclination angle calculation unit 42, a left and right wheel load fluctuation estimation unit 43, a limit value correction amount calculation unit 44, an inclination angle restriction unit 45, and an actuator drive control. Part 46.
The turning traveling state detection unit 41 inputs various data from the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, the wheel speed sensor 24, and the slip angle sensor 25.

The target inclination angle calculation unit 42 calculates the target inclination angle θ ^* for inclining the vehicle body 2 using the input information from the turning traveling state detection unit 41. For example, there is a calculation method described in JP-A-2005-112300. Specifically, the target inclination angle of the vehicle body 2 is increased in the steering direction as the steering angle detected by the steering angle sensor 21 is increased. Further, as the yaw rate detected by the yaw rate sensor 22 increases, the target inclination angle of the vehicle body 2 is increased toward the inside of the turn. Further, the larger the lateral acceleration detected by the lateral acceleration sensor 23, the larger the target inclination angle of the vehicle body 2 is to the inside of the turn. Further, as the slip angle detected by the slip angle sensor 25 is larger, the target inclination angle of the vehicle body 2 is increased to the inside of the turn. Further, the vehicle speed is calculated from the wheel speed detected by the wheel speed sensor 24, and the target inclination angle corresponding to at least one of the steering angle, the yaw rate, the lateral acceleration, and the slip angle is increased more inside the turn as the calculated vehicle speed is higher. Make it bigger.

  The left and right wheel load fluctuation estimation unit 43 uses the input information from the turning traveling state detection unit 41 to calculate the wheel load fluctuation up to an assumed future time using both a general vehicle dynamics model and an actuator dynamics model. Predict. Specifically, since the vehicle dynamics model and the drive motor 3 can be expressed by a state equation, the state equation discretized by the sampling time of the vehicle controller 26 is used to achieve an expected future time in a method similar to preview control. Predict wheel load fluctuations. The predicted time is determined in advance, and for example, a time constant at which the drive motor 3 operates may be set.

The left and right wheel load fluctuation estimation unit 43 uses the input information from the turning traveling state detection unit 41 and uses both a general vehicle dynamics model and an actuator dynamics model to calculate the left and right wheels up to the estimated future time. Estimate wheel load fluctuation (deviation). Specifically, wheel load fluctuation estimation processing in FIG. 5 described later is executed to estimate wheel load fluctuation.
The limit value correction amount calculation unit 44 uses the input information from the turning state detection unit 41 to calculate a limit value correction amount that is a correction amount for a physical (actual) limit wheel load. In the present embodiment, an off-line calculation method is shown as the simplest method. Specifically, limit value correction amount calculation processing in FIG. 6 described later is executed to calculate the limit value correction amount.

The tilt angle limiting unit 45 uses the input information from the target tilt angle calculating unit 42 and the left and right wheel load fluctuation estimating unit 43 and the input information from the limit value correction amount calculating unit 44 to limit the target tilt angle. I do. Specifically, an inclination angle limiting process in FIG. 7 described later is executed to limit the target inclination angle with the control allowable inclination angle.
The actuator drive control unit 46 performs drive control of the drive motor 3 so as to achieve the target tilt angle after the limiting process by the tilt angle limiting unit 45. For example, servo control by PID control may be used.

Next, left and right wheel load fluctuation estimation processing executed by the left and right wheel load fluctuation estimation unit 43 will be described.
FIG. 5 is a flowchart showing left and right wheel load fluctuation estimation processing.
First, in the process of step S11, a predicted future time for prediction of wheel load fluctuation is determined. This predicted time may be set by, for example, a time constant at which the drive motor 3 operates. As a result, the limit time during which the drive motor 3 quickly affects the wheel load fluctuation is known.
In subsequent step S12, the number of samples required for the prediction time is calculated using the future prediction time. Specifically, the number of samples to be predicted is obtained as follows.
Number of samples = predicted time / sampling time However, the sampling time may be a sampling time during which the vehicle controller 26 operates, for example.

In the subsequent process of step S13, the wheel load due to the operation of the vehicle dynamics model with the inclination angle as the input U in the vehicle dynamics model (frequency characteristics) discretized at the sampling time using the number of samples calculated in step S12. A difference equation with fluctuation as output ΔW1 can be expressed as follows.
x _{t + 1} , 1 = A ₁ x _t , 1 + B ₁ u _t
ΔW ₁ = H ₁ x _t , 1
Using the above difference equation, the wheel load fluctuation ΔW1 at each sampling time up to the future prediction time is calculated. Specifically, when the number of samples is N and the sampling time is ΔT, the following is calculated.

Thereby, the motion of the wheel load fluctuation | variation by the vehicle dynamics model until the part for prediction time can be estimated.
In the subsequent processing of step S14, in the actuator dynamics model (frequency characteristics) discretized at the sampling time using the number of samples calculated in step S12, the inclination angle is input U, and the wheel by the operation of the vehicle dynamics model is used. A differential equation with load variation as output ΔW2 can be expressed as follows.
x _{t +} 1, ₂ = A ₂ x _t , 2 + B ₂ u _t
ΔW ₂ = H ₂ x _t , 2
Using the above difference equation, the wheel load fluctuation ΔW2 at each sampling time up to the future prediction time is calculated. Specifically, the following is calculated in the same manner as described above.

Thereby, the motion of the wheel load fluctuation | variation by the actuator dynamics model until the part for prediction time can be estimated.
In the subsequent process of step S15, the left and right wheel load fluctuations are predicted by performing the following calculation using the wheel load fluctuations in the respective sample numbers calculated in step S13 and step S14. However, i is 1-N.
ΔW _{(t + i} ΔT ₎ = ΔW _{1 (t + i} ΔT ₎ + ΔW _{2 (t + i} ΔT ₎

Next, limit value correction amount calculation processing executed by the limit value correction amount calculation unit 44 will be described.
FIG. 6 is a flowchart showing limit value correction amount calculation processing.
First, in the process of step S21, the roll resonance frequency possessed by the vehicle tilt dynamics model is calculated. As a result, a frequency band in which the wheel load fluctuation is most moved by the inclination of the vehicle is found.
In the subsequent step S22, the gain of the roll resonance frequency in the nominal model used in the target tilt angle calculation unit 42 is calculated. This is assumed to be ΔFn for the following calculation.

In the subsequent process of step S23, the gain of the roll resonance frequency in the model when there is an assumed modeling error is calculated. In order to perform the following calculation, this is ΔFe. Here, one or more modeling errors may be assumed.
In the subsequent step S24, the gain ratio in the model having a modeling error with respect to the nominal model is calculated using the processing results in steps S22 and S23. Specifically, when the modeling error is singular, for example, the gain ratio is calculated by the following equation.
Gain ratio = (ΔFe−ΔFn) / ΔFn

When there are a plurality of modeling errors, for example, the gain ratio is calculated by the following equation.
Gain ratio = MAX ((ΔFe−ΔFn) / ΔFn)
In the subsequent process of step S25, the limit value correction amount with respect to the total weight of the vehicle is calculated using the gain ratio obtained in the process of step S24. Specifically, for example, the limit value correction amount is calculated by the following equation.
Limit value correction amount = gain ratio x total vehicle weight

Note that the limit value correction amount may be adjusted according to the assumed variation in vehicle weight. For example, the greater the assumed variation in vehicle weight, the larger the limit value correction amount.
Further, the limit value correction amount may be adjusted according to the assumed variation in the center of gravity of the vehicle. For example, the greater the variation in the assumed height of the center of gravity of the vehicle, the larger the limit value correction amount.

Next, an inclination angle restriction process executed by the inclination angle restriction unit 45 will be described.
FIG. 7 is a flowchart showing the tilt angle limiting process.
First, in the process of step S31, a control limit wheel load different from a physical (actual) limit wheel load is calculated as follows.
Limit wheel load for control = total vehicle weight−limit value correction amount In the subsequent process of step S32, the left / right wheel load fluctuation ΔW estimated by the left / right wheel load fluctuation estimating unit 43 exceeds the limit wheel load for control obtained in step S31. The allowable tilt angle for control is calculated so as not to be present.

In the subsequent process of step S33, the allowable tilt angle for control obtained in step S32 is compared with the target tilt angle obtained by the target tilt angle calculation unit 42, and if the target tilt angle is larger than the allowable tilt angle for control, As shown below, the final target tilt angle is limited to the allowable tilt angle for control.
Target tilt angle ← Control allowable tilt angle On the other hand, if the target tilt angle is smaller than the control allowable tilt angle, as shown below, the target tilt angle obtained by the target tilt angle calculation unit 42 is maintained, and is finally finalized. The target inclination angle is not correct (no correction).
Target tilt angle ← Target tilt angle

<Action>
During turning, the target inclination angle calculation unit 42 calculates a target inclination angle for inclining the vehicle body in the roll direction on the inside of the turning, and the actuator drive control unit 46 controls driving of the drive motor 3 according to the target inclination angle. When the vehicle body 2 is tilted, the wheel load changes transiently.
At this time, if the tire ground contact property on one side is lowered, the vehicle stability during turning is affected. Although it is conceivable to determine the tilt angle of the vehicle body in consideration of the vehicle dynamics model, if there is input such as vehicle parameter variation or modeling error, it may not be possible to compensate for wheel load variation.

  Therefore, the left and right wheel load fluctuation calculation unit 43 estimates the left and right wheel load fluctuations according to the turning state of the vehicle and the target inclination angle (steps S11 to S15), and the limit value correction amount calculation unit 44 calculates the vehicle load. A limit value correction amount for the physical limit wheel load when the left and right wheel loads fluctuate is calculated according to the turning state (steps S21 to S25). Then, the limit angle correction amount is subtracted from the physical limit wheel load to calculate the limit wheel load for control by the inclination angle limiter 45 (step S31), so that the left and right wheel load fluctuation does not exceed the limit wheel load for control. Then, a restriction process is performed on the target inclination angle (steps S32 and S33).

FIG. 8 is a conceptual diagram of the control limit wheel load.
Here, the center line drawn with a broken line is a position where there is no deviation in the left and right wheel loads, the left and right wheel load fluctuations occur, and the larger the left and right wheel load deviation, the farther away from the center line, the physically It means approaching the limit wheel load. The limit wheel load for control described above is a value offset to the center line side by the limit value correction amount from the physical limit wheel load.

  In this way, while estimating the left and right wheel load fluctuations, the control limit wheel load is set from the limit value correction amount, and the target inclination angle at which the left and right wheel load fluctuations are predicted so as not to exceed this control limit wheel load. Therefore, even if there is a parameter variation or a modeling error, the wheel load variation can be compensated. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

FIG. 9 is a time chart showing operational effects.
In the figure, (a) is a time chart showing the wheel load fluctuation when the present embodiment is not applied and there is no parameter fluctuation or modeling error. Here, the left and right wheel loads do not exceed the physical limit wheel loads.
In the figure, (b) is a time chart showing wheel load fluctuations when the present embodiment is not applied and there are parameter fluctuations and modeling errors. Here, the left and right wheel loads may exceed the physical limit wheel loads due to the influence of parameter variations and modeling errors.

In the figure, (c) is a time chart showing the wheel load fluctuation when the present embodiment is applied and there is a parameter fluctuation or a modeling error. Here, if there is a parameter variation or modeling error, the control limit wheel load may be exceeded, but the physical limit wheel load will not be exceeded.
In addition, the left and right wheel load fluctuation estimation unit 43 predicts left and right wheel load fluctuations according to the vehicle dynamics model and the actuator dynamics model. Specifically, according to the vehicle dynamics model, the left and right wheel load fluctuations are predicted according to the yaw rate and lateral acceleration of the vehicle.

In this way, by using the inexpensive yaw rate sensor 22 used in general commercial vehicles and the lateral acceleration sensor 23 that responds at high speed, it is possible to accurately predict left and right wheel load fluctuations.
In addition, the left and right wheel load fluctuation estimating unit 43 predicts the left and right wheel load fluctuations according to the target inclination angle according to the actuator dynamics model.
In this way, the left and right wheel load fluctuations when the vehicle body is tilted can be predicted with higher accuracy.

Further, the limit value correction amount calculation unit 44 calculates the limit value correction amount according to the assumed variation in the vehicle weight and the vehicle center of gravity. That is, the limit value correction amount is increased as the variation in the assumed vehicle weight is larger and the variation in the estimated vehicle center of gravity is larger.
In this way, by adjusting the limit correction amount according to the variation in vehicle weight and the variation in the center of gravity of the vehicle, the vehicle body is tilted so that the left and right wheel load fluctuations fall within the physical limit wheel load range. be able to.

  As described above, the drive motor 3 corresponds to the “actuator”, and the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, the wheel speed sensor 24, the slip angle sensor 25, and the turning traveling state detection unit 41 are “turning traveling state”. Corresponds to “detection means”. Further, the target inclination angle calculation unit 42 corresponds to “target inclination angle calculation means”, the left and right wheel load fluctuation estimation part 43 corresponds to “left and right wheel load fluctuation estimation means”, and the limit value correction amount calculation part 44 sets “limit”. Corresponds to “value correction amount calculating means”. Further, the processing in step S31 corresponds to “control limit wheel load calculation means”, the processing in step S33 corresponds to “inclination angle limiting means”, and the actuator drive control unit 46 corresponds to “drive control means”.

"effect"
(1) The vehicle body tilt control device includes a drive motor 3 that tilts the vehicle body in the roll direction, a turning state detection unit 41 that detects a turning state of the vehicle, and a turning state detected by the turning state detection unit 41. Accordingly, a target inclination angle calculation unit 42 that calculates a target inclination angle for inclining the vehicle body in the roll direction on the inside of the turn is provided. The left and right wheel load fluctuation estimating unit 43 that estimates the left and right wheel load fluctuations according to the turning state detected by the turning state detecting unit 41 and the target inclination angle calculated by the target inclination angle calculating unit 42, and turning driving A limit value correction amount calculation unit 44 that calculates a limit value correction amount for the physical limit wheel load when the left and right wheel loads fluctuate in accordance with the turning state detected by the state detection unit 41. Furthermore, the process of step S31 for calculating the limit wheel correction load by subtracting the limit value correction amount calculated by the limit value correction amount calculator 44 from the physical limit wheel load, and the left and right wheels estimated by the left and right wheel load fluctuation estimation unit 43 In step S33, the limit process is performed on the target inclination angle calculated by the target inclination angle calculation unit 42 so that the wheel load fluctuation does not exceed the control limit wheel load calculated in the process in step S31. And an actuator drive control unit 46 that drives and controls the actuator according to the target inclination angle subjected to the restriction process.

  In this way, while estimating the left and right wheel load fluctuations, the control limit wheel load is set from the limit value correction amount, and the target inclination angle at which the left and right wheel load fluctuations are predicted so as not to exceed this control limit wheel load. Therefore, even if there is a parameter variation or a modeling error, the wheel load variation can be compensated. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

(2) In the vehicle body tilt control device, the left and right wheel load fluctuation estimation unit 43 predicts the left and right wheel load fluctuation according to the vehicle dynamics model and the actuator dynamics model.
Thus, the left and right wheel load fluctuations can be accurately estimated by predicting the left and right wheel load fluctuations according to the vehicle dynamics model and the actuator dynamics model.

(3) The vehicle body tilt control device detects the yaw rate of the vehicle by the turning travel state detection unit 41 (yaw rate sensor 22), and the left and right wheel load fluctuation estimation unit 43 according to the vehicle dynamics model, the turning state detection unit 41 ( The left and right wheel load fluctuations are predicted according to the yaw rate detected by the yaw rate sensor 22).
Thus, by using the inexpensive yaw rate sensor 22 used in general commercial vehicles, it is possible to predict the left and right wheel load fluctuations.

(4) The vehicle body tilt control device detects the lateral acceleration of the vehicle by the turning traveling state detection unit 41 (lateral acceleration sensor 23), and the left and right wheel load fluctuation estimation unit 43 follows the vehicle dynamics model and performs the turning traveling state detection unit. The left and right wheel load fluctuations are predicted according to the lateral acceleration detected by 41 (lateral acceleration sensor 23).
Thus, by using the lateral acceleration sensor 23 that responds at high speed, it is possible to estimate the left and right wheel load fluctuations with higher accuracy.

(5) In the vehicle body tilt control device, the left and right wheel load fluctuation estimation unit 43 predicts the left and right wheel load fluctuations according to the target inclination angle calculated by the target inclination angle calculation unit 42 according to the actuator dynamics model.
Thus, by predicting the left and right wheel load fluctuations according to the target inclination angle calculated by the target inclination angle calculation unit 42, the left and right wheel load fluctuations generated by the inclination motion can be accurately estimated.

(6) In the vehicle body tilt control device, the limit value correction amount calculation unit 44 calculates the limit value correction amount according to the assumed variation in vehicle weight.
In this way, by calculating the limit value correction amount according to the assumed vehicle weight variation, if the vehicle weight variation is within the assumed range, the left and right wheel load fluctuations are within the physical limit wheel load range. The vehicle body can be tilted to fit.

(7) In the vehicle body tilt control device, the limit value correction amount is increased by the limit value correction amount calculation unit 44 as the assumed variation in vehicle weight increases.
In this way, by increasing the limit value correction amount as the assumed vehicle weight variation increases, if the vehicle weight variation is within the assumed range, the left and right wheel load fluctuations are within the physical limit wheel load range. The vehicle body can be tilted so that it fits in.

(8) The vehicle body tilt control device calculates the limit value correction amount by the limit value correction amount calculation unit 44 in accordance with the assumed variation in the center of gravity of the vehicle.
In this way, by calculating the limit value correction amount according to the assumed variation in the center of gravity of the vehicle, if the variation in the center of gravity of the vehicle is within the assumed range, the left and right wheel load fluctuation is within the range of the physical limit wheel load. The vehicle body can be tilted so that it fits inside.

(9) The vehicle body tilt control device causes the limit value correction amount calculation unit 44 to increase the limit value correction amount as the assumed variation in the center of gravity of the vehicle increases.
In this way, by increasing the limit value correction amount as the assumed variation in the center of gravity of the vehicle increases, if the variation in the center of gravity of the vehicle is within the assumed range, the left and right wheel load fluctuations The vehicle body can be tilted so that it falls within the range.

(10) In the vehicle body tilt control method, the turning state detection unit 41 detects the turning state of the vehicle, and the target inclination angle calculation unit 42 inclines the vehicle body in the roll direction on the inside of the turn according to the turning state. A target inclination angle for calculating the target inclination angle is calculated. Further, the left and right wheel load fluctuation estimating unit 43 estimates the left and right wheel load fluctuations according to the turning traveling state and the target inclination angle, and the limit value correction amount calculating unit 44 calculates the left and right wheel load fluctuations according to the turning traveling state. The limit value correction amount for the physical limit wheel load is calculated. Then, the control limit wheel load is calculated by subtracting the limit value correction amount from the physical limit wheel load by the process of step S31, and the left and right wheel load fluctuations do not exceed the control limit wheel load by the process of step S33. Then, a restriction process is performed on the target inclination angle, and the actuator drive control unit 46 controls driving of the actuator according to the restricted inclination angle.

  In this way, while estimating the left and right wheel load fluctuations, the control limit wheel load is set from the limit value correction amount, and the target inclination angle at which the left and right wheel load fluctuations are predicted so as not to exceed this control limit wheel load. Therefore, even if there is a parameter variation or a modeling error, the wheel load variation can be compensated. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

<< Second Embodiment >>
"Constitution"
FIG. 10 is a system configuration diagram showing the second embodiment.
The difference from the first embodiment is that the slip angle sensor 25 is not used. That is, when the slip angle is necessary when predicting the left / right wheel load fluctuation, information obtained from the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, and the wheel speed sensor 24 is used, for example, a Kalman filter. May be used to estimate the slip angle.
Further, a state observer may be used by using information obtained from the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, and the wheel speed sensor 24.
Further, a disturbance observer may be used by using information obtained from the steering angle sensor 21, the yaw rate sensor 22, the lateral acceleration sensor 23, and the wheel speed sensor 24.

<Action>
As mentioned above, even if not all vehicle motion states can be detected, if an estimator is used, even if there is parameter variation or wheel load variation of a model with modeling error, it depends on the running state of the vehicle. Left and right wheel load fluctuations can be estimated. Therefore, it is possible to limit the target inclination angle so that the left and right wheel load fluctuations do not exceed the control limit wheel load, and compensate for wheel load fluctuations even if there are parameter fluctuations or modeling errors. Can do. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.
"effect"
(1) The vehicle body tilt control device estimates the slip angle via the estimator by the turning travel state detection unit 41.
Thus, the slip angle sensor can be omitted by estimating the slip angle via the estimator.

<< Third embodiment >>
"Constitution"
In the third embodiment, the limit value correction amount is calculated in consideration of the driver's steering pattern.
FIG. 11 is a flowchart showing limit value correction amount calculation processing according to the third embodiment.
In addition, the calculation of this embodiment can also be calculated offline, and the following step processing is calculated offline.
First, in the process of step S41, an assumed driver's steering frequency characteristic is calculated. For example, when the steering of the driver is expressed by a combination of a plurality of sinusoidal signals, the steering frequency characteristic corresponding to the steering frequency is obtained. Further, when assuming a so-called fish hook turn in which the steering direction is largely and continuously switched as the driver's steering, a steering frequency characteristic corresponding thereto may be obtained.

In the subsequent process of step S42, the gain of the roll resonance frequency in the nominal model used in the target tilt angle calculation unit 42 is calculated. This is assumed to be ΔFn for the following calculation.
In the subsequent process of step S43, the gain of the roll resonance frequency in the model when there is an assumed modeling error is calculated. In order to perform the following calculation, this is ΔFe. Here, one or more modeling errors may be assumed.

In the subsequent process of step S44, the gain ratio in the model having a modeling error with respect to the nominal model is calculated using the processing results of step S42 and step S43. Specifically, when the modeling error is singular, for example, the gain ratio is calculated by the following equation.
Gain ratio = (ΔFe−ΔFn) / ΔFn
When there are a plurality of modeling errors, for example, the gain ratio is calculated by the following equation.
Gain ratio = MAX ((ΔFe−ΔFn) / ΔFn)

In the process of step S45, the power at the steering frequency is calculated using, for example, FFT (Fourier transform) using the information on the steering frequency characteristic obtained in step S41. In addition to FFT, power may be calculated using, for example, Wavelet transform.
In the subsequent step S46, the gain ratio normalized by the power is calculated using the gain ratio and the power obtained in steps S44 and S45. Specifically, for example, it can be expressed as a sum of multiplication of gain and power in the entire steering frequency band, and is described by the following equation.

However, P (ω) is power, G (ω) is a gain ratio, and ωmax is a maximum expected frequency.
In the subsequent process of step S47, the limit value correction amount for the total weight of the vehicle is calculated using the gain ratio obtained in step S46. Specifically, for example, the limit value correction amount is calculated by the following equation.
Limit value correction amount = gain ratio x total vehicle weight

<Action>
FIG. 12 is a conceptual diagram showing limit value correction amount calculation processing according to the third embodiment.
In the present embodiment, the assumed steering frequency characteristic of the driver is calculated (step S41), the power in the steering frequency characteristic is calculated (step S45), and the gain ratio normalized by the power is calculated (step S46). The limit value correction amount is calculated using this gain ratio (step S47).
Thus, by calculating the limit value correction amount in consideration of the driver's steering pattern, it is possible to more effectively compensate for wheel load fluctuations even if there are parameter fluctuations and modeling errors. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

"effect"
(1) In the vehicle body tilt control device, the limit value correction amount calculation unit 44 calculates the limit value correction amount according to the steering frequency.
In this way, by calculating the limit value correction amount in consideration of the steering frequency, it is possible to compensate for wheel load fluctuations even if there are parameter fluctuations or modeling errors. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

(2) In the vehicle body tilt control device, the limit value correction amount is increased by the limit value correction amount calculation unit 44 as the fluctuation with respect to the assumed steering frequency increases.
As described above, by increasing the limit value correction amount as the fluctuation with respect to the assumed steering frequency increases, it is possible to compensate for the wheel load fluctuation even when the fluctuation in the steering operation speed occurs. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

<< 4th embodiment >>
"Constitution"
In the fourth embodiment, the limit value correction amount is calculated while considering the driver's steering pattern in real time.
FIG. 13 is a flowchart showing limit value correction amount calculation processing according to the fourth embodiment.
In the calculation in the present embodiment, the following step processing is calculated online.
First, in the process of step S51, an assumed driver's steering frequency characteristic is calculated. For example, when the steering of the driver is expressed by a combination of a plurality of sinusoidal signals, the steering frequency characteristic corresponding to the steering frequency is obtained. Further, when assuming a so-called fish hook turn in which the steering direction is largely and continuously switched as the driver's steering, a steering frequency characteristic corresponding thereto may be obtained.

In the subsequent step S52, the gain of the roll resonance frequency in the nominal model used by the target tilt angle calculation unit 42 is calculated. This is assumed to be ΔFn for the following calculation.
In the subsequent step S53, the gain of the roll resonance frequency in the model when there is an assumed modeling error is calculated. In order to perform the following calculation, this is ΔFe. Here, one or more modeling errors may be assumed.

In the subsequent step S54, the gain ratio in the model having a modeling error with respect to the nominal model is calculated using the processing results in steps S52 and S53. Specifically, when the modeling error is singular, for example, the gain ratio is calculated by the following equation.
Gain ratio = (ΔFe−ΔFn) / ΔFn
When there are a plurality of modeling errors, for example, the gain ratio is calculated by the following equation.
Gain ratio = MAX ((ΔFe−ΔFn) / ΔFn)

In the subsequent process of step S55, a pattern for steering by the driver online for the past T seconds is extracted using information from the steering angle sensor 21 mounted on the vehicle 20. Thereby, the feature of the driver's steering pattern can be detected in real time.
In the subsequent step S56, the power at the steering frequency is calculated by using, for example, FFT (Fourier transform) using the information on the steering frequency characteristic of the driver obtained in step S55. In addition to FFT, power may be calculated using, for example, Wavelet transform.
In the subsequent step S57, the gain ratio normalized by the power is calculated using the gain ratio and power obtained in steps S54 and S56. Specifically, for example, it can be expressed as a sum of multiplication of gain and power in the entire steering frequency band, and is described by the following equation.

However, P (ω) is power, G (ω) is a gain ratio, and ωmax is a maximum expected frequency.
In the subsequent step S58, a limit value correction amount for the total weight of the vehicle is calculated using the gain ratio obtained in step S57. Specifically, for example, the limit value correction amount is calculated by the following equation.
Limit value correction amount = gain ratio x total vehicle weight

<Action>
FIG. 14 is a conceptual diagram showing limit value correction amount calculation processing of the fourth embodiment.
In the present embodiment, a pattern that the driver steers online is extracted for the past T seconds (step S55), a pattern of the extracted steering pattern is calculated (step S56), and a gain ratio normalized by power is calculated ( In step S57, a limit value correction amount is calculated using this gain ratio (step S58).
In this way, by calculating the limit value correction amount in consideration of the driver's steering pattern in real time, even if there are parameter fluctuations and modeling errors in accordance with the driver's steering operation that changes from moment to moment, The wheel load fluctuation can be compensated more effectively. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

"effect"
(1) In the vehicle body tilt control device, the limit value correction amount is increased by the limit value correction amount calculation unit 44 as the fluctuation with respect to the assumed steering frequency increases.
In this way, by increasing the limit value correction amount as the fluctuation with respect to the assumed steering frequency is larger, it is possible to more effectively compensate for wheel load fluctuations even if fluctuations in the speed of the steering operation occur. it can. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

(2) In the vehicle body tilt control device, the limit value correction amount is increased by the limit value correction amount calculation unit 44 as the variation with respect to the steering frequency increases.
Thus, by increasing the limit value correction amount as the variation with respect to the steering frequency increases, the limit value correction amount is changed according to the speed of the driver's steering operation. Can be compensated. Thereby, the fall of tire grounding property can be suppressed and the stability at the time of turning can be improved.

DESCRIPTION OF SYMBOLS 1 Wheel 2 Car body 3 Drive motor 11 Knuckle 12 Upper link 13 Lower link 14 Body frame 15 Lean arm 16 Shock absorber 17 Coil spring 20 Vehicle 21 Steering angle sensor 22 Yaw rate sensor 23 Lateral acceleration sensor 24 Wheel speed sensor 25 Slip angle sensor 26 Vehicle Control controller 41 Turning state detection unit 42 Target inclination angle calculation unit 43 Left and right wheel load fluctuation estimation unit 44 Limit value correction amount calculation unit 45 Inclination angle limitation unit 46 Actuator drive control unit

Claims (12)

An actuator for tilting the vehicle body in the roll direction;
Turning state detection means for detecting turning state of the vehicle;
Target inclination angle calculating means for calculating a target inclination angle for inclining the vehicle body in the roll direction on the inside of the turning according to the turning traveling state detected by the turning traveling state detecting means;
Left and right wheel load fluctuation estimating means for estimating left and right wheel load fluctuations according to the turning running state detected by the turning running state detecting means and the target inclination angle calculated by the target inclination angle calculating means;
According to the turning state detected by the turning state detection means , the physical limit is the load when the full load of the load supported by the left and right wheels is loaded on one of the left and right wheels when the left and right wheel load changes Limit value correction amount calculating means for calculating a limit value correction amount for the wheel load;
A control limit wheel load calculating means for calculating a control limit wheel load by subtracting the limit value correction amount calculated by the limit value correction amount calculating means from the physical limit wheel load;
The target inclination angle calculated by the target inclination angle calculation means so that the left and right wheel load fluctuation estimated by the left and right wheel load fluctuation estimation means does not exceed the control limit wheel load calculated by the control limit wheel load calculation means. Tilt angle limiting means for performing a limiting process on
A vehicle body tilt control device comprising: drive control means for driving and controlling the actuator according to a target tilt angle that has been restricted by the tilt angle restricting means. The turning traveling state detecting means detects a yaw rate of the vehicle,
The right and left wheel load variation estimating means, in response to the yaw rate detected by the previous SL turning traveling state detecting means, the vehicle body tilt control device according to claim 1, characterized in that predicting the left and right wheel load variation. The turning traveling state detecting means detects a lateral acceleration of the vehicle,
The right and left wheel load fluctuation estimation means before SL depending on the lateral acceleration detected by turning traveling state detecting means, the vehicle body tilt control device according to claim 1 or 2, characterized in that predicting the left and right wheel load variation. The right and left wheel load fluctuation estimation means before SL in accordance with the target tilt angle calculated in the target tilting angle calculating means, according to any one of claims 1 to 3, characterized in that predicting the left and right wheel load variation Body tilt control device. The vehicle body tilt control device according to any one of claims 1 to 4 , wherein the limit value correction amount calculation means calculates a limit value correction amount according to an assumed variation in vehicle weight. 6. The vehicle body tilt control device according to claim 5 , wherein the limit value correction amount calculating means increases the limit value correction amount as the assumed variation in vehicle weight increases. The vehicle body tilt control device according to any one of claims 1 to 6 , wherein the limit value correction amount calculation means calculates a limit value correction amount according to an assumed variation in the center of gravity of the vehicle. . 8. The vehicle body tilt control device according to claim 7 , wherein the limit value correction amount calculation means increases the limit value correction amount as the assumed variation in the center of gravity of the vehicle increases. The vehicle body tilt control device according to any one of claims 1 to 8 , wherein the limit value correction amount calculation means calculates a limit value correction amount according to a steering frequency. 10. The vehicle body tilt control device according to claim 9 , wherein the limit value correction amount calculation means increases the limit value correction amount as the variation with respect to an assumed steering frequency increases. 11. The vehicle body tilt control device according to claim 9, wherein the limit value correction amount calculation unit increases the limit value correction amount as the variation with respect to the input steering frequency increases. An actuator for inclining the vehicle body in the roll direction is provided, the turning traveling state of the vehicle is detected, a target inclination angle for inclining the vehicle body in the roll direction on the inside of the turning is calculated according to the turning traveling state, and the turning traveling is performed The left and right wheel load fluctuations are estimated according to the state and the target inclination angle, and when the left and right wheel loads fluctuate according to the turning state, the full load of the load supported by the right and left wheels is on one of the left and right wheels. Calculating a limit value correction amount for a physical limit wheel load that is a load at the time, subtracting the limit value correction amount from the physical limit wheel load to calculate a limit wheel load for control, and the left and right wheel load fluctuations are A vehicle body tilt control method, wherein a limit process is performed on the target tilt angle so as not to exceed a limit wheel load for control, and the actuator is driven and controlled according to the target tilt angle subjected to the limit process.

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