Vibration information estimation device and suspension device

Abstract

To provide a vibration information estimation device capable of accurately estimating vibration information on a rear wheel side with respect to the traveling direction of a vehicle, and further, to provide a suspension device capable of improving ride comfort in a vehicle.SOLUTION: A vibration information estimation device 1 includes: a roll acceleration detection unit 2 that detects a roll acceleration φ of a vehicle body B; a vertical acceleration detection unit 3 that detects vertical accelerations αzrl, αzrr of the vehicle body B immediately above rear wheels Wrl, Wrr; a correction unit 4 that corrects the vertical accelerations αzrl, αzrr on the basis of the roll acceleration φ; and an observer 5 that estimates vertical relative vibration information between the vehicle body B and the rear wheels Wrl, Wrr of a vehicle V on the basis of the state equation of a one-wheel model 5a using vertical accelerations αzrla, αzrra corrected by the correction unit 4 as input. Further, a suspension device Sd includes a vibration information estimation device 1, a control device C, and a damper D or actuator, and the control device C controls the damper D or actuator based on vibration information.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vibration information estimating device and a suspension device. [Background technology]

[0002] In a suspension system that aims to improve ride comfort in a vehicle, etc., and that is equipped with a variable damping force shock absorber that is interposed between the vehicle body and wheels, and a control device that controls the control force exerted by the shock absorber in accordance with the skyhook control law, it is necessary to detect the vertical speed of the vehicle body and the stroke speed of the suspension system.

[0003] The vertical velocity of the vehicle body can be obtained by integrating the vertical acceleration of the vehicle body detected by an acceleration sensor installed on the vehicle body. Furthermore, the stroke velocity can be obtained by either installing a stroke sensor that detects the relative displacement between the vehicle body and the wheels, detecting the stroke displacement, and differentiating the stroke displacement, or by installing acceleration sensors that detect the vertical acceleration of the vehicle body and the wheels, respectively, integrating the detected accelerations of the vehicle body and the wheels, and then calculating the difference between the two to obtain the stroke velocity.

[0004] In order to obtain the vertical speed and stroke speed of the vehicle body in this way, at least two sensors are required, which not only makes the control device for the shock absorber expensive, but also requires space to install the sensors, so there is a demand for an inexpensive, space-saving control device.

[0005] To meet this demand, there has been a proposal to apply a vibration information estimation device to a control device that uses a one-wheel model observer that estimates stroke displacement as a state quantity, with the observed quantity being the vertical acceleration of the vehicle body.With a vibration information estimation device configured in this way, all that is needed to estimate the stroke displacement between one wheel and the vehicle body is a single acceleration sensor, making the control device inexpensive and space-saving.

[0006] Specifically, the vibration information estimation device incorporates the nonlinear characteristics of the shock absorber in the form of a map into the observer model, and performs compensation to maintain the observer gain at an appropriate value depending on the damping coefficient of the shock absorber or the magnitude of the control command given to the damping valve of the shock absorber, thereby improving the estimation accuracy of the stroke displacement (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-31125 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in conventional vibration information estimation devices, stroke displacement is estimated using a one-wheel model observer, and therefore the roll of the vehicle body in the lateral direction is not taken into consideration at all.

[0009] Therefore, for example, when a four-wheeled vehicle is traveling on a sinusoidal road where the left and right wheels are in opposite phase, there is a problem in that the phase of the estimated stroke displacement on the rear wheel side is delayed relative to the actual measured value due to the influence of the roll of the vehicle body that occurs when the front wheels are traveling on the sinusoidal road.

[0010] Therefore, with conventional vibration information estimation devices, it is difficult to accurately estimate vibration information such as stroke displacement and stroke speed, and in suspension devices that use vibration information estimated by a vibration information estimation device, the vibration of the vehicle body cannot be effectively suppressed due to errors between the actual measured values ​​and the estimated values ​​of the vibration information, and further improvements in vehicle ride comfort are desired.

[0011] Therefore, an object of the present invention is to provide a vibration information estimation device that can accurately estimate vibration information on the rear wheel side relative to the vehicle's traveling direction, and another object is to provide a suspension device that can improve the ride comfort of the vehicle. [Means for solving the problem]

[0012] The vibration information estimation device according to the problem-solving means of the present invention comprises a roll acceleration detection unit that detects roll acceleration, which is acceleration in the roll direction of a vehicle body of a vehicle having wheels on the front, rear, left and right sides, and a vertical acceleration detection unit that detects vertical acceleration, which is acceleration in the up and down direction of the vehicle body directly above the rear wheels in the direction of travel of the vehicle. On the front wheels in the direction of travel of the vehicle The system is comprised of a correction unit that corrects the vertical acceleration based on the roll acceleration, and an observer that uses the vertical acceleration corrected by the correction unit as input and estimates relative vertical vibration information between the vehicle body and rear wheels based on the state equation of a single-wheel model.

[0013] According to the vibration information estimation device configured in this manner, On the front wheels in the direction of travel of the vehicle Since a correction unit that corrects the vertical acceleration based on the roll acceleration is provided, it is possible to remove the acceleration component due to roll that interferes with the estimation of the stroke displacement by the observer from the vertical acceleration.

[0014] Furthermore, the correction unit in the vibration information estimation device may correct the vertical acceleration detected when the rear wheels pass over the same road surface as the front wheels in the traveling direction of the vehicle, based on the roll acceleration obtained when the front wheels pass over the same road surface. With the vibration information estimation device configured in this way, when the front and rear wheels pass over the same road surface, the vertical acceleration can be corrected using the roll angular velocity obtained when the front wheels travel on the same road surface, thereby enabling more accurate estimation of vibration information.

[0015] Furthermore, the suspension system may include a shock absorber with adjustable damping force or an actuator with adjustable thrust force interposed between the vehicle body and the rear wheels, a control device that controls the shock absorber or the actuator, and a vibration information estimation device, where the control device controls the shock absorber or the actuator based on the vibration information estimated by the vibration information estimation device. With a suspension system configured in this manner, the shock absorber or the actuator can be controlled based on the vibration information estimated with high accuracy, thereby effectively suppressing vibration of the vehicle body and improving ride comfort in the vehicle. [Effects of the Invention]

[0016] The vibration information estimating device of the present invention can accurately estimate vibration information on the rear wheel side relative to the vehicle traveling direction. Also, the suspension device of the present invention can improve the ride comfort of the vehicle. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing a suspension device according to an embodiment mounted on a vehicle; [Figure 2] 1 is a diagram illustrating a configuration of a vibration information estimation device according to an embodiment. [Figure 3] FIG. 1 is a diagram illustrating a configuration of a control device in a suspension device according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of a hardware configuration of a vibration information estimation device and a control device according to an embodiment. [Figure 5] FIG. 2 is a diagram showing the configuration of a processing unit that performs processing of the vibration information estimation device and the control device. [Figure 6] FIG. 1 is a diagram showing a one-wheel model of a vehicle. [Figure 7] 1 is a flowchart showing a processing procedure of a vibration information estimation device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figures 1 and 2, a vibration information estimation device 1 includes a roll acceleration detection unit 2 that detects roll acceleration φ, which is the acceleration in the roll direction of a vehicle body B of a vehicle V having front, rear, left, and right wheels Wfl, Wfr, Wrl, and Wrr; a vertical acceleration detection unit 3 that detects vertical accelerations αzrl, αzrr, which are the accelerations in the vertical direction of the vehicle body B directly above the rear wheels Wrl, Wrr in the direction of travel of the vehicle V; a correction unit 4 that corrects the vertical acceleration based on the roll acceleration φ; and an observer 5 that receives the vertical accelerations αzrl, αzrr corrected by the correction unit 4 as input and estimates stroke displacements Xl, Xr as relative vibration information between the vehicle body B and the rear wheels Wrl, Wrr of the vehicle V based on a state equation of a single wheel model. Note that the vibration information may be stroke displacement, which is the relative displacement in the vertical direction between the vehicle body B and the rear wheels Wrl, Wrr, as well as information that can grasp relative vibration between the two, such as the relative speed or relative acceleration between the two. In addition, the front and rear of the vehicle V are defined based on the direction of travel of the vehicle V, with the wheels located in front of the direction of travel of the vehicle V being the front wheels, and the wheels located behind the direction of travel of the vehicle V being the rear wheels.

[0019] Furthermore, as shown in Figures 1 and 3, the suspension device Sd of this embodiment includes a shock absorber D with adjustable damping force interposed between the vehicle body B and the rear wheels Wrl, Wrr, a control device C that controls the shock absorber D, and a vibration information estimation device 1, and the control device C controls the shock absorber D based on the stroke displacement, which is vibration information obtained by the vibration information estimation device 1.

[0020] As shown in FIG. 3, the control device C includes a stroke displacement estimation device 30 that estimates the stroke displacement between the vehicle body B and the front wheels Wfl, Wfr, a target damping force calculation unit 20 that calculates target damping forces Ffl, Ffr, Frl, Frr using the stroke displacement of the front wheels Wfl, Wfr estimated by the stroke displacement estimation device 30 and the stroke displacement of the rear wheels Wrl, Wrr estimated by the vibration information estimation device 1, and a command current determination unit 21 that calculates target currents Ifl, Ifr, Irl, Irr to be supplied from the target damping forces Ffl, Ffr, Frl, Frr to the damping force adjustment units F of the dampers D of each of the four wheels Wfl, Wfr, Wrl, Wrr.

[0021] A vehicle V is equipped with suspension springs S interposed in parallel with shock absorbers D between a vehicle body B and the front, rear, left, and right wheels Wfl, Wfr, Wrl, and Wrr of the vehicle body B, and the vehicle body B is elastically supported by the suspension springs S. Although not shown in detail, the shock absorbers D are equipped with a damping force adjusting unit F therein, and the damping force can be changed in accordance with the current supplied to the damping force adjusting unit F by a control device C. In this manner, the damping force of the shock absorbers D is controlled by the control device C. The damping force adjusting unit F is, for example, a solenoid valve that adjusts the opening area or the valve opening pressure in accordance with the supplied current. Note that the damping force adjusting unit F may also be a valve unit equipped with a damping valve and a solenoid valve that adjusts the back pressure that urges the valve element of the damping valve toward the valve seat.

[0022] 4, the vibration information estimation device 1 includes, as hardware, acceleration sensors 10, 11, and 12 that are provided on a vehicle body B and detect vertical acceleration at installation positions on the vehicle body B, and a processing unit 13 that performs processing to estimate vibration information from the acceleration detected by the acceleration sensors 10, 11, and 12, and each unit of the vibration information estimation device 1 is realized by processing by the processing unit 13. The control device C in the suspension device Sd of this embodiment shares some of its hardware with the vibration information estimation device 1, and includes the acceleration sensors 10, 11, and 12 and the processing unit 13 that performs processing to determine a target damping force to be generated by the shock absorber D, and a drive circuit 14 that supplies current to the damping force adjustment unit F in response to a command from the processing unit 13.

[0023] 5, the arithmetic processing device 13 includes a CPU (Central Processing Unit) 13a, a memory 13b that stores programs for the CPU 13a to perform processes as the vibration information estimation device 1 and the control device C and provides a storage area necessary for the processes of the CPU 13a, an interface 13c that enables signal exchange among the CPU 13a, the memory 13b, the acceleration sensors 10, 11, and 12, and the drive circuit 14, and a bus 13d that communicatively connects these devices to one another. The drive circuit 14 is provided for each of the four shock absorbers D interposed between the vehicle body B and each of the four wheels Wfl, Wfr, Wrl, and Wrr of the vehicle V, and supplies a current of a current value specified by a command from the arithmetic processing device 13 to the damping force adjuster F. The drive circuit 14 may be, for example, a drive circuit other than a drive circuit that performs PWM drive.

[0024] The CPU 13a processes the vertical accelerations α1, α2, and α3 of the vehicle body B detected by the acceleration sensors 10, 11, and 12 by executing an operating system and other programs, and also controls the memory 13b. In addition to a read-only memory (ROM), the memory 13b is equipped with a random access memory (RAM) that provides a storage area necessary for the arithmetic processing of the CPU 13a, and stores programs used in the arithmetic processing of the CPU 13a in the ROM. Note that the programs used in the arithmetic processing of the CPU 13a may be stored in a storage device other than the memory 13b, and may be read into the RAM in the memory 13b at the time of execution and executed on the RAM.

[0025] Each component of the vibration information estimation device 1 will be described in detail below. The roll acceleration detection unit 2 detects roll acceleration φ, which is the acceleration of the vehicle body B in the roll direction. Furthermore, the vertical acceleration detection unit 3 detects vertical accelerations αzrl, αzrr, which are the accelerations of the vehicle body B in the vertical direction directly above the rear wheels Wrl, Wrr in the traveling direction of the vehicle V. The roll acceleration detection unit 2 and the vertical acceleration detection unit 3 include three acceleration sensors 10, 11, and 12 installed on the vehicle body B, and detect the roll acceleration φ and the vertical accelerations αzrl, αzrr, which are the accelerations in the roll direction of the vehicle body B, from the vertical accelerations α1, α2, and α3, which are the accelerations in the vertical direction at three locations on the vehicle body B, detected by these acceleration sensors 10, 11, and 12. More specifically, the processing in the roll acceleration detection unit 2 and the processing in the vertical acceleration detection unit 3 are realized by an arithmetic processing device 13 processing the accelerations α1, α2, and α3.

[0026] The three acceleration sensors 10, 11, and 12 are installed at three arbitrary locations on the vehicle body B that are not on the same line in the front-to-back or left-to-right direction, and detect the vertical accelerations α1, α2, and α3 of the vehicle body B at the respective installation locations.

[0027] The calculation processing device 13 determines the vertical accelerations αzrl, αzrr directly above the rear wheels Wrl, Wrr of the vehicle body B from the accelerations α1, α2, α3 detected by the acceleration sensors 10, 11, 12. Specifically, the calculation processing device 13 regards the vehicle body B as a rigid body and obtains the vertical accelerations of any three locations that are not on the same line in the fore-aft or lateral directions of the vehicle body B, thereby obtaining the accelerations of the vehicle body B in the vertical direction, fore-aft rotation, and lateral rotation. Therefore, from these accelerations, the calculation processing device 13 determines the bounce acceleration, which is the vertical acceleration at the center of gravity of the vehicle body B, the pitch acceleration, which is the angular acceleration of the fore-aft rotation at the center of gravity, and the roll acceleration φ, which is the angular acceleration of the lateral rotation at the center of gravity.

[0028] After determining the bounce acceleration, pitch acceleration, and roll acceleration φ, the calculation processing device 13 determines the vertical accelerations αzrl and αzrr of the vehicle body B immediately above the rear wheels Wrl and Wrr using the tread value Lt of the rear wheels Wrl and Wrr and the wheelbase value Lh. If the roll acceleration in the direction in which the vehicle body B rotates to the left relative to the vehicle's traveling direction is defined as positive, the vertical acceleration αzrl of the vehicle body B immediately above the rear wheel Wrl is determined by adding the bounce acceleration value, the pitch acceleration value multiplied by Lh / 2, and the roll acceleration φ value multiplied by Lt / 2. In addition, the vertical acceleration αzrr of the vehicle body B immediately above the rear wheel Wrr is determined by subtracting the roll acceleration φ value multiplied by Lt / 2 from the sum of the bounce acceleration value and the pitch acceleration value multiplied by Lh / 2.

[0029] In this way, the arithmetic processing device 13 processes the accelerations α1, α2, α3 detected by the acceleration sensors 10, 11, 12, thereby performing processing as the roll acceleration detection unit 2 and the vertical acceleration detection unit 3. The arithmetic processing device 13 detects the roll acceleration φ and the vertical accelerations αzrl, αzrr directly above the rear wheels Wrl, Wrr at a predetermined sampling period. The arithmetic processing device 13 also stores the calculated roll acceleration φ in the memory 13b. The memory 13b is provided with an area for storing the roll acceleration φ calculated within a period of about several seconds, and when the area becomes full, the oldest roll acceleration φ is overwritten with the newest roll acceleration φ. death The value of the roll acceleration φ stored in the memory 13b is updated accordingly.

[0030] When an acceleration sensor is used to detect the vertical acceleration of the vehicle body B directly above the rear wheels Wrl, Wrr, the acceleration detected by the acceleration sensor is the vertical accelerations αzrl, αzrr directly above the rear wheels Wrl, Wrr, and therefore these acceleration sensors may be used to configure the vertical acceleration detection unit 3. Also, when an acceleration sensor is used to directly detect the vertical accelerations αzrl, αzrr directly above the rear wheels Wrl, Wrr, the calculation processing unit 13 may divide the difference between the vertical accelerations αzrl, αzrr by the tread value Lt between the rear wheels Wrl, Wrr to obtain the roll acceleration φ of the vehicle body B, thereby realizing the roll acceleration detection unit 2. Furthermore, as will be described later, the suspension device Sd of this embodiment needs to detect the vertical accelerations αzfl, αzfr, αzrl, αzrr of the vehicle body B directly above the four wheels Wfl, Wfr, Wrl, Wrr in order to control the dampers D of the four wheels Wfl, Wfr, Wrl, Wrr. Therefore, acceleration sensors may be installed at four locations on the vehicle body B directly above the four wheels Wfl, Wfr, Wrl, Wrr, and the four acceleration sensors may be used to detect the vertical accelerations αzfl, αzfr, αzrl, αzrr of the vehicle body B directly above the four wheels Wfl, Wfr, Wrl, Wrr. However, if the accelerations α1, α2, α3 detected by the three acceleration sensors 10, 11, 12 are processed to determine the bounce acceleration, pitch acceleration, and roll acceleration φ, the vertical accelerations αzfl, αzfr, αzrl, αzrr of the vehicle body B directly above the four wheels Wfl, Wfr, Wrl, Wrr can be determined, which means that one fewer acceleration sensor needs to be installed, making the suspension device Sd less expensive.

[0031] In addition, if the vehicle V is equipped with an acceleration sensor that detects the vertical acceleration of the vehicle body B, separate from the vibration information estimation device 1, the vertical accelerations αzfl, αzfr, αzrl, and αzrr of the vehicle body B directly above the front wheels Wfl, Wfr and rear wheels Wrl, Wrr may be obtained from the vehicle V via a CAN (Controller Area Network) bus or an on-board diagnosis (OBD) installed in the vehicle V.

[0032] Next, the correction unit 4 includes a correction value calculation unit 4a that calculates a correction value based on the roll acceleration φ and the speed v of the vehicle V, and an adder-subtractor 4b that calculates corrected vertical accelerations αzrla, αzrra based on the vertical accelerations αzrl, αzrr of the vehicle body B directly above the rear wheels Wrl, Wrr and the correction value calculated by the correction value calculation unit 4a. Note that the speed v of the vehicle V is information that is generally detected by the vehicle V, and therefore may be obtained from the vehicle V via the CAN bus or OBD, but as shown in Figure 2, the speed v may also be obtained by providing a speed sensor 7 that detects the speed v of the vehicle V.

[0033] Specifically, the processing of each part of the correction unit 4 is executed by the arithmetic processing device 13. The arithmetic processing device 13 processes the speed sensor 7 that detects the speed v of the vehicle V, the roll acceleration φ detected by the roll acceleration detection unit 2, and the speed v detected by the speed sensor 7, to correct the vertical acceleration of the vehicle body B immediately above the rear wheels Wrl, Wrr. In this way, the arithmetic processing device 13 realizes the correction unit 4 that corrects the vertical acceleration of the vehicle body B immediately above the rear wheels Wrl, Wrr by executing the above-mentioned processing.

[0034] The correction unit 4 assumes that, while the vehicle V is traveling, the rear wheels Wrl, Wrr will pass over the same road surface as the front wheels Wfl, Wfr have passed over in the traveling direction of the vehicle V, and corrects the vertical accelerations αzrl, αzrr detected when the rear wheels Wrl, Wrr pass over the same road surface, based on the roll acceleration φ obtained when the front wheels Wfl, Wfr passed over the same road surface. In other words, the correction unit 4 performs processing to remove from the vertical accelerations αzrl, αzrr of the rear wheels Wrl, Wrr the influence of the roll acceleration φ of the vehicle body B that will occur when the rear wheels Wrl, Wrr pass over the same road surface as the front wheels Wfl, Wfr.

[0035] When the front wheels Wfl, Wfr reach and pass the road surface at a certain point while the vehicle V is traveling, and the vehicle V then continues straight ahead, the rear wheels Wrl, Wrr, which are located behind the front wheels Wfl, Wfr and on the same line along the fore-and-aft direction of the vehicle V, will pass over the same road surface as the front wheels Wfl, Wfr after a certain number of seconds. If the speed v of the vehicle V is constant, the wheelbase value Lh, which is the distance between the front wheels Wfl, Wfr and the rear wheels Wrl, Wrr of the vehicle V, is known, and therefore the delay time t from when the front wheels Wfl, Wfr pass over a road surface until the rear wheels Wfl, Wfr reach the same road surface, can be found by calculating Lh / v. If the speed v of vehicle V changes after the front wheels Wfl, Wfr pass over a road surface, the speed v is monitored, and the rear wheels Wrl, Wrr reach the same road surface when the integrated value of the speed v after the front wheels Wfl, Wfr pass over the road surface is equal to the wheelbase value Lh. By making the above assumption, it is possible to determine how many seconds before the rear wheels Wrl, Wrr reach the same road surface that the front wheels Wfl, Wfr passed over the same road surface. Furthermore, since the roll acceleration φ of vehicle body B when the rear wheels Wrl, Wrr pass over the same road surface as the front wheels Wfl, Wfr is expected to be similar to the roll acceleration when the front wheels Wfl, Wfr pass over the same road surface, the roll acceleration φ when the front wheels Wfl, Wfr pass over the same road surface can be estimated as the roll acceleration φ when the rear wheels Wrl, Wrr pass over the same road surface.

[0036] From the above, the correction value calculation unit 4a calculates the delay time t from the time when the front wheels Wfl, Wfr pass over a certain road surface to the time when the rear wheels Wrl, Wrr are expected to pass over the same road surface, based on the speed v of the vehicle V and the wheelbase value Lh. As mentioned above, at the time when the rear wheels Wrl, Wrr are expected to pass over the same road surface as the front wheels Wfl, Wfr passed over, the roll acceleration φ obtained at the time before the delay time t can be considered to be the roll acceleration when the rear wheels Wrl, Wrr pass over the same road surface. Therefore, the correction value calculation unit 4a calculates the correction value α by using the roll acceleration φ obtained at the time before the time t to correct the acceleration component due to roll included in the vertical accelerations αzrl, αzrr. φSpecifically, the calculation processing unit 13 calculates the correction value α φ =φ×(Lt / 2) to obtain the acceleration component, thereby implementing the correction value calculation unit 4a. Furthermore, the adder-subtractor 4b calculates the vertical acceleration αzrl of the vehicle body B directly above the left rear wheel Wrl and adds the correction value α φ is added to remove the acceleration component due to roll contained in the vertical acceleration αzrl of the vehicle body B directly above the left rear wheel Wrl, and the correction value α obtained at the time t before is added to the vertical acceleration αzrr of the vehicle body B directly above the right rear wheel Wrr. φ is subtracted to remove the acceleration component due to roll included in the vertical acceleration αzrr of the vehicle body B directly above the right rear wheel Wrr. The processing in the adder / subtractor 4b is also realized by the calculation processing device 13 performing the above-mentioned calculation processing. The correction unit 4 is thus realized by the calculation processing device 13 performing the above-mentioned calculation processing, and inputs the corrected vertical accelerations αzrla, αzrra to the observer 5. However, αzrla=αzrl+α φ , αzrra=αzrr-α φ is.

[0037] Specifically, the calculation processing device 13 calculates the aforementioned time t from the speed v of the vehicle V and the wheelbase value Lh, reads from the memory 13b the value of the roll acceleration φ obtained the time t before the time point at which the corrected vertical accelerations αzrla, αzrra are calculated, and corrects the vertical accelerations αzrl, αzrr. As described above, the correction unit 4 needs the value of the roll acceleration φ obtained the time t before the time point at which the corrected vertical accelerations αzrla, αzrra are calculated. Therefore, the calculation processing device 13 may associate the time at which the roll acceleration φ was detected when storing the roll acceleration φ in the memory 13b. Note that if there is no roll acceleration φ obtained exactly at the time t before the time point at which the corrected vertical accelerations αzrla, αzrra are calculated, the value of the roll acceleration φ obtained at the time closest to that time may be used, or the corrected vertical accelerations αzrla, αzrra may be calculated using the average value of the roll acceleration φ obtained before and after that time point.

[0038] As described above, in the vibration information estimation device 1 of this embodiment, the delay time t is calculated from the values ​​of the speed v and the wheelbase Lh, and the roll acceleration φ obtained at a time preceding the time when the processing of the correction unit 4 is performed by the delay time t is used to calculate the correction value α φ In other words, when the stroke displacement is estimated using the observer 5 from the vertical accelerations αzrl and αzrr, the roll acceleration φ detected only by the delay time t described above has an effect, so the correction unit 4 calculates the correction value α φ As mentioned above, the vertical accelerations αzrl, αzrr and the roll acceleration φ are obtained by processing the accelerations α1, α2, α3 obtained at the same time. The roll acceleration φ obtained simultaneously with the vertical accelerations αzrl, αzrr is directly multiplied by Lt / 2 to obtain the correction value α φ When the roll acceleration φ is calculated, the phase of the roll acceleration φ is delayed, so the stroke displacement cannot be accurately estimated. Therefore, when using the roll acceleration φ obtained simultaneously with the vertical accelerations αzrl and αzrr, the roll acceleration φ can be filtered according to the speed v of the vehicle V to adjust the phase so that it is appropriate for estimating the stroke displacement. Therefore, the correction unit 4 calculates the correction value α φ In addition to calculating the vertical accelerations αzrl and αzrr, the roll acceleration φ obtained at the same time is used to adjust its phase according to the velocity v, and then the correction value α φ From the viewpoint of control stability, in the filtering process of the roll acceleration φ, it is sufficient to perform either phase lag compensation or phase lead compensation as appropriate.

[0039] In this way, the calculation processing device 13 functions as a correction unit 4 that performs processing to remove the influence of roll acceleration φ from the vertical accelerations αzrl, αzrr of the rear wheels Wrl, Wrr based on the speed v of the vehicle V and the wheelbase value Lh of the vehicle V, and calculates the corrected vertical accelerations αzrla, αzrra.

[0040] The observer 5 comprises a single-wheel model 5a that represents characteristics limited to the vertical movement of the rear wheels Wrl, Wrr relative to the vehicle body B that is the object of estimation, a damping coefficient map 5b that determines the damping coefficient of the shock absorber D to be input to the single-wheel model 5a, an observer gain setting unit 5c, and a differentiator 5d, and is realized by the calculation processing unit 13 performing processing of each part of the observer 5.

[0041] As shown in Fig. 6, the one-wheel model 5a is a model including a sprung member U, an unsprung member W, a shock absorber D and a suspension spring S interposed between the sprung member U and the unsprung member W, and a tire Ti between the unsprung member W and the road surface R. The one-wheel model 5a receives the corrected vertical acceleration αzrla (αzrra) and the observer gain G output by the observer gain setting unit 5c, and estimates and outputs the stroke displacement.

[0042] If the mass of the sprung member U is Mu, the mass of the unsprung member W is Mw, the spring constant of the suspension spring S is Ks, the spring constant of the tire Ti is Kt, the displacement of the sprung member U is Xu, the displacement of the unsprung member W is Xw, and the displacement of the road surface R is Xr, the equation of motion of the sprung member U is given by the following equation (1), and the equation of motion of the unsprung member W is given by the following equation (2). In equations (1) and (2), Cd(i) represents the damping coefficient of the shock absorber D, and (i) indicates that the damping coefficient changes depending on the current i applied to the damping force adjustment unit F.

[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049] The damping coefficient map 5b contains a map showing the relationship between the stroke speed of the shock absorber D, the current i supplied to the damping force adjustment unit F, and the damping coefficient Cd(i). A differentiator 5d is provided before the damping coefficient map 5b, and the stroke speed obtained by differentiating the stroke displacement estimated by the one-wheel model 5a by the differentiator 5d is input to the damping coefficient map 5b. The current i supplied to the damping force adjustment unit F uses a current value specified by a command given by the control device C to the drive circuit 14, and the current value specified by the command is input to the damping coefficient map 5b as the current i. Specifically, the calculation processing device 13 differentiates the stroke displacement estimated by the one-wheel model 5a to obtain the stroke speed, and performs map calculations using the stroke speed and the current i as parameters to obtain the damping coefficient Cd(i), thereby realizing the damping coefficient map 5b and the differentiator 5d.

[0050] The observer gain setting unit 5c includes an adder 5c1 that calculates the deviation between the vertical acceleration of the vehicle body B directly above the rear wheel Wrl (Wrr) estimated by the one-wheel model 5a and the corrected vertical acceleration αzrla (αzrra), and a gain calculation unit 5c2 that calculates the observer gain G by inputting the deviation calculated by the adder 5c1 and the damping coefficient Cd(i) output by the damping coefficient map 5b, and inputs the obtained gain G to the one-wheel model 5a.

[0051] Gain calculation unit 5c2 calculates observer gain G so that the deviation calculated by adder 5c1 converges to 0. In vibration information estimation device 1 of the present embodiment, gain calculation unit 5c2 calculates observer gain G from the minimum and maximum values ​​that damping coefficient Cd(i), which is the output value of damping coefficient map 5b, can take, and covariance matrices Q and R. The processing of adder 5c1 and gain calculation unit 5c2 is realized by the arithmetic processing of calculation processing device 13.

[0052] The processing of the observer 5 is performed for each input of the corrected vertical acceleration αzrla of the left rear wheel Wrl and the corrected vertical acceleration αzrra of the right rear wheel Wrr, and the calculation processing device 13 calculates the stroke displacement between the vehicle body B and the left rear wheel Wrl and the stroke displacement between the vehicle body B and the right rear wheel Wrr at a predetermined calculation cycle.

[0053] The stroke displacement between the vehicle body B and the left rear wheel Wrl and the stroke displacement between the vehicle body B and the right rear wheel Wrr thus obtained are input to the target damping force calculation unit 20 in the control device C together with the vertical accelerations αzrl and αzrr of the rear wheels Wrl and Wrr.

[0054] In this embodiment, the control device C is equipped with a vertical acceleration detection unit 31 that detects vertical accelerations αzfl, αzfr of the vehicle body B directly above the front wheels Wfl, Wfr, and a stroke displacement estimation device 30 that estimates a stroke displacement between the vehicle body B and the front wheels Wfl, Wfr, in order to control the damping forces of the shock absorbers D interposed between the vehicle body B and the front wheels Wfl, Wfr of the vehicle V. As described above, in addition to the stroke displacement estimation device 30, the control device C is also equipped with a target damping force calculation unit 20 that calculates target damping forces Ffl, Ffr, Frl, Frr using the stroke displacements of the rear wheels Wrl, Wrr estimated by the vibration information estimation device 1 and the stroke displacements of the front wheels Wfl, Wfr estimated by the stroke displacement estimation device 30, and a command current determination unit 21 that calculates target currents Ifl, Ifr, Irl, Irr to be supplied from the target damping forces Ffl, Ffr, Frl, Frr to the damping force adjustment units F of the dampers D of each of the four wheels Wfl, Wfr, Wrl, Wrr.

[0055] Here, when estimating the stroke displacement between the vehicle body B and the front wheels Wfl, Wfr in the traveling direction of the vehicle V, the phase of the estimated stroke displacement does not lag even if the acceleration component due to roll acceleration is not removed. Therefore, in the process of estimating the stroke displacement between the vehicle body B and the front wheels Wfl, Wfr arranged on the front side in the traveling direction of the vehicle V, the processing of the correction unit 4 in the configuration of the vibration information estimation device 1 is not required. Although not shown, the stroke displacement estimation device 30 for the front wheels has a configuration in which the roll acceleration detection unit 2 and the correction unit 4 are omitted from the configuration of the vibration information estimation device 1, and the detected vertical acceleration is input to the observer 5 without correction to estimate the stroke displacement.

[0056] Therefore, in the stroke displacement estimation device 30, the vertical accelerations αzfl, αzfr of the vehicle body B directly above the front wheels Wfl, Wfr are input without correction to the one-wheel model 5a in the observer 5 to estimate the stroke displacement between the vehicle body B and the front wheels Wfl, Wfr. Note that the vertical accelerations αzfl, αzfr of the vehicle body B directly above the front wheels Wfl, Wfr can be calculated by the calculation processing device 13 using the bounce acceleration, pitch acceleration, and roll acceleration φ calculated as described above, and the tread value Ltf and wheelbase value Lh of the front wheels Wfl, Wfr, and the vertical acceleration detection unit 31 is realized by the processing of this calculation processing device 13.

[0057] The stroke displacement between the vehicle body B and the front wheels Wfl, Wfr estimated by the stroke displacement estimation device 30 in this way and the vertical accelerations αzfl, αzfr of the vehicle body B directly above the front wheels Wfl, Wfr are both input to the target damping force calculation unit 20 of the control device C. In addition, the target damping force calculation unit 20 also receives the stroke displacement at the rear wheels Wrl, Wrr and the vertical accelerations αzrl, αzrr of the vehicle body B directly above the rear wheels Wrl, Wrr estimated by the vibration information estimation device 1.

[0058] The target damping force calculation unit 20 calculates target damping forces Ffl, Ffr, Frl, Frr of the shock absorbers D of the four wheels Wfl, Wfr, Wrl, Wrr (front, rear, left, and right) in order to suppress vibration of the vehicle body B by skyhook control based on Karnop's law. Specifically, the target damping force calculation unit 20 differentiates the stroke displacements at the four wheels Wfl, Wfr, Wrl, Wrr to obtain stroke velocities Szfl, Szfr, Szrl, Szrr, and integrates the respective vertical accelerations αzfl, αzfr, αzrl, αzrr to obtain vertical velocities Vzfl, Vzfr, Vzrl, Vzrr, by multiplying each by a skyhook damping coefficient Cs to obtain the required damping force Ffl * ,Ffr * ,Frl * ,Frr * Ask for.

[0059] The shock absorber D cannot exert a force in a direction that promotes expansion during an expansion operation, and cannot exert a force in a direction that promotes contraction during a contraction operation. * ,Ffr * ,Frl * ,Frr * If the direction of is a direction in which shock absorber D cannot exert force, it is necessary to minimize the damping force of shock absorber D according to Karnop's law so that vehicle body B is not vibrated by the damping force exerted by shock absorber D. For example, the required damping force Ffl for shock absorber D of front wheel Wfl is *Whether the direction of the shock absorber D is in a direction in which it cannot exert force can be determined by the sign of the product of the stroke speed Szfl at the front wheels Wfl and the corresponding up-and-down speed Vzfl. If the direction of the speed of the vehicle body B moving upward is taken as positive, and the stroke speed when the shock absorber D is extended is taken as positive, when both the speed of the vehicle body B and the stroke speed of the shock absorber D are positive values, the shock absorber D is in a situation in which it can exert a damping force that suppresses the rise of the vehicle body B. When both the speed of the vehicle body B and the stroke speed of the shock absorber D are negative values, the shock absorber D is in a situation in which it can exert a damping force that suppresses the descent of the vehicle body B. When the signs of the values ​​of the speed of the vehicle body B and the stroke speed of the shock absorber D are different, the damping force exerted by the shock absorber D will promote the rise or descent of the vehicle body B. Therefore, when the value of the product of the speed of the vehicle body B and the stroke speed of the shock absorber D is positive, the direction in which the damping force of the shock absorber D at the front wheels Wfl is generated is the required damping force Ffl. * The same determination is made for the remaining three wheels Wfr, Wrl, and Wrr, and the shock absorber D determines the required damping force Ffr * ,Frl * ,Frr * It can be determined whether it is possible to generate a damping force in the same direction as the direction of the vehicle.

[0060] The target damping force calculation unit 20 calculates the required damping force Ffl for the shock absorber D of each of the four wheels Wfl, Wfr, Wrl, and Wrr. * ,Ffr * ,Frl * ,Frr * When it is determined that a damping force in the same direction as the required damping force Ffl can be generated, * ,Ffr * ,Frl * ,Frr * are the target damping forces Ffl, Ffr, Frl, and Frr, respectively.

[0061] On the other hand, the target damping force calculation unit 20 calculates the required damping force Ffl for the shock absorber D of each of the four wheels Wfl, Wfr, Wrl, and Wrr. * ,Ffr * ,Frl * ,Frr *If it is determined that the damping forces in the direction that coincides with the direction of the shock absorber D cannot be generated, the target damping forces Ffl, Ffr, Frl, and Frr are set to the minimum values ​​that the shock absorber D can generate.

[0062] The target damping force calculation unit 20 calculates the target damping force using skyhook control, which is intended to suppress vibration of the vehicle body B, but in addition to or instead of the skyhook control, the final target damping force may be calculated based on a control law for suppressing vibration of the wheels Wfl, Wfr, Wrl, and Wrr or a control law for stabilizing the posture of the vehicle body B.

[0063] The target damping forces Ffl, Ffr, Frl, and Frr calculated by the target damping force calculation unit 20 are input to a command current determination unit 21. The command current determination unit 21 calculates target currents Ifl, Ifr, Irl, and Irr to be supplied to the damping force adjustment unit F so that each shock absorber D for each of the four wheels Wfl, Wfr, Wrl, and Wrr exerts a damping force according to the target damping forces Ffl, Ffr, Frl, and Frr. The command current determination unit 21 has, for example, a map or function for calculating a target current using the target damping force as a parameter, and calculates the target currents Ifl, Ifr, Irl, and Irr from the target damping forces Ffl, Ffr, Frl, and Frr using the map or function. Note that in a case where the flow rate passing through the damping force adjustment unit F changes depending on the stroke speed of the shock absorber D and the damping force generated by the shock absorber D changes with respect to the current, the command current determination unit 21 may calculate the target currents Ifl, Ifr, Irl, and Irr using a map or function for calculating a current using the stroke speed and the target damping force as parameters. The processing of each part of the control device C is specifically executed by the arithmetic processing device 13, and therefore the control device C is realized by the processing of the arithmetic processing device 13.

[0064] In this way, the control device C receives inputs of the vertical accelerations αzfl, αzfr, αzrl, αzrr and stroke displacements of the vehicle body B directly above the four wheels Wfl, Wfr, Wrl, Wrr of the vehicle V, calculates the target currents Ifl, Ifr, Irl, Irr, and outputs commands indicative of the currents to each drive circuit 14. The commands indicative of the currents are also input to the damping coefficient map 5b in the observer 5 and used in calculations to calculate the damping coefficients in the damping coefficient map 5b. The drive circuit 14 then supplies a current of the value indicative of the command to the damping force adjuster F. Therefore, the suspension device Sd, which is equipped with the shock absorber D, the vibration information estimation device 1, and the control device C, processes the sequentially detected vertical accelerations αzfl, αzfr, αzrl, αzrr and controls the damping force generated by the shock absorber D, thereby suppressing vibration of the vehicle body B and improving ride comfort in the vehicle V.

[0065] The configurations of the vibration information estimation device 1, the control device C, and the shock absorber D in the suspension device Sd have been described above. Below, the processing in the arithmetic processing device 13 for realizing the vibration information estimation device 1 will be described using the flowchart shown in FIG.

[0066] The calculation processing device 13 repeatedly executes the following steps F1 to F7 at a predetermined calculation cycle. First, the calculation processing device 13 obtains the vertical accelerations αzrl, αzrr and roll acceleration φ of the vehicle body B directly above the rear wheels Wrl, Wrr from the accelerations α1, α2, α3 detected by the acceleration sensors 10, 11, 12 (step F1). Next, the calculation processing device 13 calculates the correction value α based on the values ​​of the speed v of the vehicle V, the roll acceleration φ, the wheel base Lh, and the tread Lt. φ is calculated (Step F2).

[0067] Next, the calculation processing unit 13 calculates the correction value α φ The calculation processing device 13 then calculates the deviation between the corrected vertical accelerations αzrla, αzrra and the estimated values ​​of the vertical accelerations calculated in the previous calculation cycle (step F4).

[0068] Furthermore, the calculation processing device 13 performs map calculations using as parameters a command indicating the current i to be applied to the damping force adjustment section F of the shock absorber D, which is obtained by processing as the control device C, and the stroke speed obtained by differentiating the stroke displacement obtained in the previous calculation cycle, to obtain the damping coefficient Cd(i) (step F5).

[0069] Then, the calculation processing device 13 calculates the observer gain G from the deviation calculated in step F4 and the damping coefficient Cd(i) calculated in step F5 (step F6), sets the observer gain G of the observer 5, and performs the calculations required for processing as the observer 5 using the corrected vertical accelerations αzrla, αzrra to calculate the stroke displacement (step F7).

[0070] The calculation processing device 13 repeatedly executes the processes from step F1 to step F7 at a predetermined calculation cycle to calculate the stroke displacement from the vertical accelerations αzrl, αzrr and the roll acceleration φ. In this way, each part of the vibration information estimation device 1 is realized by the calculation processing device 13 executing the processes from step F1 to step F7.

[0071] As described above, the vibration information estimation device 1 of this embodiment is configured to include a roll acceleration detection unit 2 that detects roll acceleration φ, which is the acceleration in the roll direction of the body B of the vehicle V having wheels Wfl, Wfr, Wrl, and Wrr on the front, rear, left, and right sides; a vertical acceleration detection unit 3 that detects vertical accelerations αzrl, αzrr, which are the acceleration in the vertical direction of the body B directly above the rear wheels Wrl, Wrr in the direction of travel of the vehicle V; a correction unit 4 that corrects the vertical accelerations αzrl, αzrr based on the roll acceleration φ; and an observer 5 that uses the vertical accelerations αzrla, αzrra corrected by the correction unit 4 as input and estimates the relative stroke displacement (vibration information) in the vertical direction between the body B of the vehicle V and the rear wheels Wrl, Wrr based on the state equation of the single-wheel model 5a.

[0072] The vibration information estimation device 1 configured in this manner is provided with a correction unit 4 that corrects the vertical accelerations αzrl, αzrr based on the roll acceleration φ, and therefore can remove from the vertical accelerations αzrl, αzrr the acceleration components due to roll that interfere with the estimation of stroke displacement by the observer 5. Therefore, the vibration information estimation device 1 can remove the acceleration components due to roll from the vertical accelerations αzrl, αzrr, and therefore the phase of the stroke displacement (vibration information) estimated by the observer 5 does not lag behind the actual stroke displacement, and therefore the stroke displacement (vibration information) can be estimated with high accuracy.

[0073] Furthermore, in the vibration information estimation device 1 of this embodiment, the correction unit 4 assumes that the rear wheels Wrl, Wrr pass over the same road surface as the front wheels Wfl, Wfr in the traveling direction of the vehicle V, and corrects the vertical accelerations αzrl, αzrr detected when the rear wheels Wrl, Wrr pass over the same road surface based on the roll acceleration φ obtained when the front wheels Wfl, Wfr pass over the same road surface. According to the vibration information estimation device 1 configured in this manner, when the front wheels Wfr, Wfr and the rear wheels Wrl, Wrr pass over the same road surface, the vertical accelerations αzrl, αzrr can be corrected using the roll angular velocity φ obtained when the front wheels Wfr, Wfr travel on the same road surface, thereby making it possible to estimate the stroke displacement (vibration information) more accurately.

[0074] Furthermore, the suspension device Sd of this embodiment includes a shock absorber D with adjustable damping force interposed between the vehicle body B and the rear wheels Wrl, Wrr, a control device C that controls the shock absorber D, and a vibration information estimation device 1. The control device C controls the shock absorber D based on the stroke displacement (vibration information) estimated by the vibration information estimation device 1. With the suspension device Sd configured in this manner, the shock absorber D is controlled based on the stroke displacement (vibration information) estimated with high accuracy, thereby effectively suppressing vibration of the vehicle body B and improving ride comfort in the vehicle. Note that the suspension device Sd of this embodiment includes the shock absorber D and controls the shock absorber D with the control device C. However, instead of the shock absorber D, an actuator that can adjust the generated thrust force may be provided and controlled by the control device C. Even in this case, the suspension device Sd can control the actuator based on the stroke displacement (vibration information) estimated with high accuracy, thereby effectively suppressing vibration of the vehicle body B and improving ride comfort in the vehicle. Note that when controlling the actuator, a map or function for calculating the thrust force generated by the actuator may be provided instead of the damping coefficient map 5b in the vibration information estimation device 1.

[0075] Furthermore, although the vibration information is assumed to be stroke displacement in the above description, the vibration information estimated by the observer 5 may be stroke speed or stroke acceleration. Furthermore, in addition to stroke displacement and stroke speed, the observer 5 may also estimate the vertical speed or displacement of the vehicle body B, or the acceleration, speed or displacement of the wheels Wfr, Wfr, Wrl, Wrr. The type of vibration information to be selected may be determined depending on the state quantity used in the control of the suspension device Sd.

[0076] In the suspension device Sd of this embodiment, the stroke displacement of the front wheels Wfl, Wfr is estimated by the stroke displacement estimation unit 30, which does not perform processing by the correction unit 4. However, it is possible to configure the vibration information estimation device 1 to be able to process the stroke displacement (vibration information) of both the front wheels Wfl, Wfr and the rear wheels Wrl, Wrr of the vehicle V, and to estimate the stroke displacement (vibration information) of the wheels on the front side in the direction of travel without performing processing by the correction unit 4, and to estimate the stroke displacement (vibration information) of the wheels on the rear side in the direction of travel by performing processing by the correction unit 4.

[0077] Furthermore, in the suspension device Sd of this embodiment, each part of the vibration information estimation device 1 and the control device C is realized by processing by the arithmetic processing device 13, but the vibration information estimation device 1 and the control device C may be separate and independent hardware, or each part of the vibration information estimation device 1 and the control device C may be configured by different hardware.

[0078] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0079] 1 Vibration information estimation device, 2 Roll acceleration detection unit, 3 Vertical acceleration detection unit, 4 Correction unit, 5 Observer, 5a Single-wheel model B···Vehicle body, C···Control device, D···Shock absorber, Sd···Suspension device, V···Vehicle, Wfl, Wfr···Front wheels, Wrl, Wrr···Rear wheels,

Claims

1. a roll acceleration detection unit that detects roll acceleration, which is acceleration in the roll direction of a vehicle body of a vehicle having wheels on the front, rear, left, and right sides; a vertical acceleration detection unit that detects vertical acceleration, which is acceleration of the vehicle body in the vertical direction directly above the rear wheels in the traveling direction of the vehicle; a correction unit that corrects the vertical acceleration based on the roll acceleration of a front wheel in a traveling direction of the vehicle; an observer that receives the vertical acceleration corrected by the correction unit as an input and estimates relative vibration information in the vertical direction between the body and the rear wheel of the vehicle based on a state equation of a one-wheel model; A vibration information estimation device characterized by:

2. The correction unit corrects the vertical acceleration detected when the rear wheels pass over the same road surface as the road surface passed over by the front wheels in the traveling direction of the vehicle, based on the roll acceleration acquired when the front wheels pass over the same road surface.

2. The vibration information estimation device according to claim 1.

3. a shock absorber with adjustable damping force or an actuator with adjustable thrust force interposed between the vehicle body and the rear wheel; a control device for controlling the shock absorber or the actuator; The vibration information estimation device according to claim 1 or 2, The control device controls the shock absorber or the actuator based on the vibration information estimated by the vibration information estimation device. A suspension device characterized by:

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