Suspension controls and suspension

Abstract

The present invention realizes suspension control that enables the roll and pitch of a vehicle to be synchronized. The suspension control device for controlling the suspension damping force includes: a target pitch angle calculation unit (891) that calculates a target pitch angle with reference to a roll angle signal; and a target control amount calculation unit (894) that calculates a roll attitude target control amount referenced for controlling the suspension damping force with reference to a steering torque signal and the target pitch angle.

Description

Technical Field

[0001] The invention relates to a suspension control device and a suspension device. Background Art

[0002] In controlling the running state of a vehicle, from the perspective of enhancing the safety of vehicle running, there is disclosed a method of synchronizing roll and pitch as vehicle motions by using a technique of controlling brakes or suspension (for example, see Patent Document 1).

[0003] Patent Document 1: US2004 / 0024504A

[0004] However, the above patent document does not disclose a specific control method for synchronizing roll and pitch.

[0005] One aspect of the present invention is to achieve a suspension control that is capable of synchronizing the roll and pitch of a vehicle. Summary of the Invention

[0006] In order to solve the above problems, a suspension control device according to one aspect of the present invention controls the damping force of the suspension. The suspension control device includes a target pitch angle calculation unit, which calculates the target pitch angle with reference to the roll angle signal; and a target control amount calculation unit, which calculates the target control amount with reference to the steering torque signal and the target pitch angle, and refers to the target control amount when controlling the damping force of the suspension.

[0007] In order to solve the above problems, a suspension device according to another aspect of the present invention includes a suspension and a control unit for controlling the damping force of the suspension, wherein the control unit includes a target pitch angle calculation unit, which calculates the target pitch angle with reference to the roll angle signal; and a target control quantity calculation unit, which calculates the target control quantity with reference to the steering torque signal and the target pitch angle, and refers to the target control quantity when controlling the damping force of the suspension.

[0008] According to aspects of the present invention, it is possible to synchronize the roll and pitch of a vehicle by controlling the suspension. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a diagram schematically showing an example of the configuration of a vehicle according to the first embodiment of the present invention.

[0010] Figure 2 is a block diagram showing an example of a functional configuration of a suspension control portion according to the first embodiment of the present invention.

[0011] Figure 3 is a block diagram showing an example of a functional configuration of a roll attitude control portion according to the first embodiment of the present invention.

[0012] Figure 4 : is a block diagram showing an example of the functional configuration of the roll posture target control amount according to the first embodiment of the present invention.

[0013] Figure 5 : is a block diagram showing an example of a functional configuration of a target pitch angle calculation section according to the first embodiment of the present invention.

[0014] Figure 6 This is a diagram showing an example in which the time difference between the peak values of the roll angle and the pitch angle of the vehicle is small.

[0015] Figure 7 This is a diagram showing an example in which the time difference between the peak values of the roll angle and the pitch angle of the vehicle is large.

[0016] Figure 8 : is a block diagram showing an example of a functional configuration of a target pitch angle calculation section according to the second embodiment of the present invention.

[0017] Figure 9 : is a block diagram showing an example of a functional configuration of a roll posture target control amount according to the third embodiment of the present invention.

[0018] Reference Mark List

[0019] 81: Steering angle target control amount calculation unit

[0020] 82: Steering angular velocity target control amount calculation unit

[0021] 83: Roll rate target control amount calculation unit

[0022] 84: Steering torque target control amount calculation unit

[0023] 85: Steering torque speed calculation unit

[0024] 86: Steering torque speed target control amount calculation unit

[0025] 87: Steering torque-derived target control amount selection unit

[0026] 88: Roll attitude derived target control amount selection unit

[0027] 89: Roll attitude target control amount calculation unit

[0028] 91: Absolute value calculation unit

[0029] 92, 95: Gain multiplication unit

[0030] 96: Gain setting unit

[0031] 100: Suspension

[0032] 200: Body

[0033] 300, 300A, 300B, 300C, 300D: wheels

[0034] 310, 310A, 310B, 310C, 310D: Tires

[0035] 320, 320A: Wheel speed sensor

[0036] 330: Lateral G sensor

[0037] 340: Front-rear G-sensor

[0038] 350: Yaw angular velocity sensor

[0039] 370: CAN

[0040] 410: Steering components

[0041] 420: Steering shaft

[0042] 430: Torque sensor

[0043] 440: Steering angle sensor

[0044] 460: Torque application unit

[0045] 470: Rack and Pinion Mechanism

[0046] 480: Rack shaft

[0047] 500: Engine

[0048] 510: Engine torque sensor

[0049] 520: Engine speed sensor

[0050] 530: Brake pressure sensor

[0051] 600: ECU

[0052] 650: Suspension control unit

[0053] 660: CAN input unit

[0054] 670: Vehicle State Estimation Unit

[0055] 671: Steering correction amount calculation unit

[0056] 673: Roll rate calculation unit

[0057] 674: State Estimation Single Wheel Model Application

[0058] 680: Ride Comfort Control Department

[0059] 681: Ceiling Control Department

[0060] 682: Roll attitude control unit

[0061] 683: Pitch attitude control unit

[0062] 684: Unsprung parts control unit

[0063] 690: Control quantity selection unit

[0064] 700: Power generation device

[0065] 800: Battery

[0066] 891, 991: Target pitch angle calculation unit

[0067] 892: Subtraction Department

[0068] 893: Pitch moment calculation unit

[0069] 894: Target control amount calculation unit

[0070] 900: Vehicle DETAILED DESCRIPTION

[0071] The inventors of the present invention have diligently studied suspension control that synchronizes the roll and pitch of a vehicle and have discovered that by controlling the suspension to synchronize the roll and pitch of a vehicle, the driver's sense of unity with the vehicle can be enhanced.

[0072] [First embodiment]

[0073] The following describes a first embodiment of the present invention in detail. First, a vehicle employing a suspension device and a suspension control device according to an embodiment of the present invention will be described. Throughout this specification, the term "with reference to" can encompass meanings such as "using," "taking into account," and "based on." Furthermore, specific examples of "controlled variables" in this specification include current values, duty cycles, damping coefficients, and damping ratios.

[0074] [Vehicle Configuration]

[0075] Figure 1 is a diagram schematically showing an example of the configuration of a vehicle 900 according to the present embodiment. Figure 1As shown, vehicle 900 includes a suspension device (suspension) 100, a vehicle body 200, wheels 300, tires 310, a steering member 410, a steering shaft 420, a torque sensor 430, a steering angle sensor 440, a torque applying portion 460, a rack and pinion mechanism 470, a rack shaft 480, an engine 500, an electronic control unit (ECU) (control device, control portion) 600, a power generation device 700, and a battery 800. Here, suspension device 100 and ECU 600 constitute the suspension device according to this embodiment.

[0076] A wheel 300 mounted with a tire 310 is suspended from the vehicle body 200 by a suspension device 100. Since the vehicle 900 is a four-wheeled vehicle, the suspension device 100, the wheel 300, and the tire 310 are provided on each of the four wheels.

[0077] The tires and wheels of the left front wheel, right front wheel, left rear wheel, and right rear wheel are also referred to as tire 310A and wheel 300A, tire 310B and wheel 300B, tire 310C and wheel 300C, and tire 310D and wheel 300D, respectively. Hereinafter, similarly, the configurations attached to the left front wheel, right front wheel, left rear wheel, and right rear wheel may be indicated by adding reference letters "A," "B," "C," and "D."

[0078] The suspension device 100 includes a hydraulic shock absorber (shock absorber), an upper arm, and a lower arm. Furthermore, as an example, the hydraulic shock absorber includes a solenoid valve, which is an electromagnetic valve for adjusting the damping force generated by the hydraulic shock absorber. However, this embodiment is not limited to this, and the hydraulic shock absorber may use an electromagnetic valve other than a solenoid valve as the electromagnetic valve for adjusting the damping force. For example, the hydraulic shock absorber may be configured such that a solenoid valve using electromagnetic fluid (magnetic fluid) is provided as the aforementioned solenoid valve.

[0079] The power generation device 700 is attached to the engine 500 , and the electricity generated by the power generation device 700 is stored in the battery 800 .

[0080] The steering member 410 operated by the driver is connected to one end of the steering shaft 420 so as to be able to transmit torque, and the other end of the steering shaft 420 is connected to the rack and pinion mechanism 470 .

[0081] The rack and pinion mechanism 470 converts the rotation of the steering shaft 420 about the axis into the displacement in the axial direction of the rack shaft 480. When the rack shaft 480 is displaced in the axial direction, the wheels 300A and 300B are steered via the tie rods and the knuckle arms.

[0082] Torque sensor 430 detects the steering torque applied to steering shaft 420, in other words, the steering torque applied to steering member 410, and provides a torque sensor signal indicating the detection result to ECU 600. More specifically, torque sensor 430 detects the torsion of a torsion bar built into steering shaft 420 and outputs the detection result as a torque sensor signal. As torque sensor 430, a well-known sensor such as a Hall effect IC, an MR element, or a magnetostrictive torque sensor can be used.

[0083] The steering angle sensor 440 detects the steering angle of the steering member 410 and provides the detection result to the ECU 600 .

[0084] The torque applying unit 460 applies assist torque or reaction torque to the steering shaft 420 according to the steering control amount supplied from the ECU 600. The torque applying unit 460 includes a motor that generates assist torque or reaction torque according to the steering control amount, and a torque transmitting mechanism that transmits the torque generated by the motor to the steering shaft 420.

[0085] In the above description, "connected so as to be able to transmit torque" means that the components are connected in such a manner that the rotation of one component causes the rotation of the other component. For example, this includes at least cases where one component and another component are integrally molded, where one component is directly or indirectly fixed to another component, and where one component and another component are connected so as to interlock with each other via a joint component or the like.

[0086] Furthermore, in the above example, a steering device in which the steering member 410 and the rack shaft 480 are always mechanically connected is used as an example, but the present embodiment is not limited thereto. For example, the steering device according to the present embodiment may be a steer-by-wire type steering device. The contents described below in this specification may also be applied to steer-by-wire type steering devices.

[0087] The ECU 600 generally controls various electronic devices included in the vehicle 900. For example, the ECU 600 controls the magnitude of the assist torque or the reaction torque applied to the steering shaft 420 by adjusting the steering control amount provided to the torque applying portion 460.

[0088] Furthermore, ECU 600 controls opening and closing of a solenoid valve included in a hydraulic shock absorber included in suspension apparatus 100 by providing a suspension control amount to the solenoid valve. To achieve this control, a power line for supplying driving power from ECU 600 to the solenoid valve is arranged.

[0089] Vehicle 900 also includes a wheel speed sensor 320 installed for each wheel 300 and detecting the wheel speed of each wheel 300; a lateral G sensor 330 detecting the lateral acceleration of vehicle 900; a longitudinal G sensor 340 detecting the longitudinal acceleration of vehicle 900; a yaw rate sensor 350 detecting the yaw rate of vehicle 900; an engine torque sensor 510 detecting the torque generated by engine 500; an engine speed sensor 520 detecting the number of revolutions of engine 500; and a brake pressure sensor 530 detecting the pressure of the brake fluid applied to the brake device. The detection results of these various sensors are provided to ECU 600.

[0090] Although not shown, vehicle 900 includes: an anti-lock braking system (ABS), which is a system that prevents wheel locking during braking; a traction control system (TCS), which suppresses slip of the vehicle wheels during acceleration, etc.; and a vehicle stability assist (VSA) controllable braking device, which is a vehicle behavior stability control system equipped with an automatic braking function or a brake assist function for yaw moment control during cornering.

[0091] Here, the ABS, TCS, and VSA compare the wheel speeds determined based on the estimated vehicle body speed with the wheel speeds detected by wheel speed sensor 320. If the two wheel speeds differ by a predetermined value or more, the ABS, TCS, and VSA determine that the vehicle is in a slipping state. Through this process, the ABS, TCS, and VSA aim to stabilize the behavior of vehicle 900 by executing optimal braking control or traction control based on the vehicle's running state.

[0092] Furthermore, provision of detection results by the above-described various sensors to the ECU 600 and transmission of control signals from the ECU 600 to each portion are performed via a controller area network (CAN) 370 .

[0093] [Suspension control unit]

[0094] Hereinafter, the ECU 600 will be described in detail by changing the drawings. The ECU 600 includes a suspension control portion 650. The ECU 600 is one aspect of the suspension control device of the present embodiment.

[0095] The suspension control portion 650 refers to detection results of various sensors included in the CAN 370 and determines the size of the suspension control amount provided to the solenoid valve included in the hydraulic shock absorber included in the suspension device 100. The process of "determining the size of the control amount" includes a case where the size of the control amount is set to zero, that is, no control amount is provided.

[0096] Next, we will refer to Figure 2 The suspension control portion 650 will be described in more detail. Figure 2 is a block diagram showing an example of the functional configuration of the suspension control section 650 .

[0097] like Figure 2 As shown, the suspension control unit 650 includes a CAN input unit 660 , a vehicle state estimation unit 670 , a steering stability / ride comfort control unit 680 , and a control amount selection unit 690 .

[0098] The CAN input unit 660 obtains various signals via the CAN 370. For example, Figure 2 As shown, the CAN input unit 660 acquires the following signals (brackets indicate acquisition sources).

[0099] Wheel speeds of the four wheels (wheel speed sensors 320A to 320D)

[0100] Yaw angular velocity (yaw angular velocity sensor 350)

[0101] Front and rear G (front and rear G sensor 340)

[0102] Lateral G (lateral G sensor 330)

[0103] Brake pressure (brake pressure sensor 530)

[0104] Engine torque (engine torque sensor 510)

[0105] Engine speed (engine speed sensor 520)

[0106] Steering angle (steering angle sensor 440)

[0107] Steering torque (torque sensor 430)

[0108] The vehicle state estimation unit 670 estimates the state of the vehicle 900 by referring to various signals acquired by the CAN input unit 660. The vehicle state estimation unit 670 outputs the sprung speed of the four wheels, the stroke speed of the four wheels, the pitch rate, the roll rate, the roll rate during cornering, and the pitch rate during acceleration / deceleration as estimation results.

[0109] like Figure 2 As shown, the vehicle state estimation unit 670 includes an acceleration / deceleration / steering correction amount calculation unit 671 , an acceleration / deceleration / steering pitch / roll rate calculation unit 673 , and a state estimation single wheel model application unit 674 .

[0110] The acceleration / deceleration / steering correction amount calculation unit 671 refers to the yaw angular velocity, front and rear G, the wheel speeds of the four wheels, the braking pressure, the engine torque and the engine speed, calculates the front and rear speeds of the vehicle body, the difference ratio between the inner and outer wheels and the adjustment gain, and then the acceleration / deceleration / steering correction amount calculation unit 671 provides the calculation results to the state estimation single wheel model application unit 674.

[0111] The acceleration / deceleration / steering pitch / roll rate calculation unit 673 calculates the roll rate during steering and the pitch rate during acceleration / deceleration with reference to the longitudinal G and the lateral G. The calculation results are provided to the steering stability / ride comfort control unit 680 .

[0112] The acceleration / deceleration / steering pitch / roll rate calculation unit 673 can be configured to further reference the suspension control variable output by the control variable selection unit 690. Furthermore, the roll rate value can be configured to use "0" as a reference value when the inclination of the vehicle 900 does not change within a predetermined minute, and the roll rate can be expressed as a deviation from the reference value. Furthermore, the acceleration / deceleration / steering pitch / roll rate calculation unit 673 can set a deadband of approximately ±0.5 in the roll rate during steering. Here, for example, "+" is marked on the left side of the vehicle 900 and "-" is marked on the right side.

[0113] State estimation single-wheel model application section 674 applies a single-wheel model for state estimation to each wheel, referring to the calculation results of acceleration / deceleration / steering correction amount calculation section 671. The model calculates the sprung speed, stroke velocity, pitch rate, and roll rate of the four wheels. The calculation results are provided to steering stability / ride comfort control section 680.

[0114] The steering stability / ride comfort control section 680 includes a skyhook control section 681 , a roll attitude control section 682 , a pitch attitude control section 683 , and an unsprung component control section 684 .

[0115] Skyhook control unit 681 performs ride comfort control (vibration suppression control) that suppresses vehicle shaking when riding on uneven road surfaces and enhances ride comfort. For example, skyhook control unit 681 determines a skyhook target control variable by referring to the sprung velocities, stroke velocities, pitch rates, and roll rates of the four wheels, and supplies the result to control variable selection unit 690.

[0116] More specifically, the skyhook control unit 681 sets a base damping force value by referring to a sprung damping force map based on sprung velocity. Furthermore, the skyhook control unit 681 calculates a skyhook target damping force by multiplying the set base damping force value by a skyhook gain. The skyhook target control amount is then determined based on the skyhook target damping force and the stroke velocity.

[0117] Roll attitude control unit 682 controls the roll attitude by calculating a roll attitude target control variable based on the roll rate during steering, a steering angle signal indicating the steering angle, and a steering torque signal indicating the steering torque. The calculated roll attitude target control variable is provided to control variable selection unit 690. The specific configuration of roll attitude control unit 682 will be described below.

[0118] The pitch attitude control unit 683 controls the pitch with reference to the pitch rate during acceleration and deceleration, determines a pitch target control amount, and provides the result to the control amount selection unit 690 .

[0119] The unsprung component control unit 684 controls the vibration suppression of the unsprung components of the vehicle 900 with reference to the wheel speeds of the four wheels, and determines the target control amount of the unsprung vibration suppression control. The determination result is provided to the control amount selection unit 690.

[0120] The control amount selection section 690 selects the target control amount having the highest value among the skyhook target control amount, the roll attitude target control amount, the pitch target control amount, and the unsprung vibration suppression control target control amount, and outputs the selected target control amount as the suspension control amount.

[0121] [Roll attitude control unit]

[0122] In the following, reference will be made to Figure 3 The roll attitude control section 682 will be described in more detail. Figure 3 : is a block diagram showing an example of the functional configuration of the roll attitude control section 682 according to the present embodiment. The roll attitude control section 682 calculates a roll attitude target control amount by referring to the roll angle signal, the actual pitch angle signal, the steering angle signal, the steering angular velocity signal, the roll rate signal, and the steering torque signal.

[0123] Here, in the case where the roll attitude control unit 682 refers to the roll angle signal, for example, the vehicle 900 may be configured to include a roll angle sensor, and the output from the roll angle sensor may be used as the roll angle signal, but the present invention is not limited thereto. For example, the roll rate calculated by the vehicle state estimation unit 670 may be configured to be integrated by the vehicle state estimation unit 670, and the roll angle obtained by the integration may be configured to be used as the roll angle signal.

[0124] In addition, when the roll attitude control unit 682 refers to the actual pitch angle signal, for example, the vehicle 900 may be configured to include a pitch angle sensor, and the output from the pitch angle sensor may be configured to be used as the pitch angle signal, but the present invention is not limited thereto. For example, the pitch rate calculated by the vehicle state estimation unit 670 may be configured to be integrated by the vehicle state estimation unit 670, and the pitch angle obtained by the integration may be configured to be used as the actual pitch angle signal.

[0125] In addition, in the case where the roll posture control unit 682 refers to the steering angular velocity signal, the steering angle signal output by the CAN input unit 660 can be configured to be differentiated by, for example, the steering stability / ride comfort control unit 680, and the steering angular velocity obtained by the differentiation can be configured to be used as a steering angular velocity signal.

[0126] Here, the roll attitude target controlled variable can be a target controlled variable that is a candidate for a suspension controlled variable. In other words, it is a target controlled variable that is referenced when controlling the damping force of the suspension. For example, the roll attitude target controlled variable calculated by the roll attitude control unit 682 can be the suspension controlled variable selected by the control variable selection unit 690. Therefore, it can be expressed as the roll attitude control unit 682 calculating the suspension controlled variable.

[0127] like Figure 3 As shown, the roll attitude control unit 682 includes a steering angle target control amount calculation unit 81, a steering angle velocity target control amount calculation unit 82, a roll rate target control amount calculation unit 83, a steering torque target control amount calculation unit 84, a steering torque velocity calculation unit 85, a steering torque velocity target control amount calculation unit 86, a steering torque derived target control amount selection unit 87, a roll attitude derived target control amount selection unit 88 and a roll attitude target control amount calculation unit 89.

[0128] The steering angle target control amount calculation unit 81 calculates the steering angle target control amount by referring to the steering angle indicated by the steering angle signal. The steering angular velocity target control amount calculation unit 82 calculates the steering angular velocity target control amount by referring to the steering angular velocity signal. Both the steering angle target control amount calculation unit 81 and the steering angular velocity target control amount calculation unit 82 refer to the steering angle signal to suppress the roll of the vehicle 900 and calculate the target control amounts so that the posture of the vehicle 900 becomes closer to being flat.

[0129] The roll rate target control amount calculation section 83 calculates the roll rate target control amount with reference to the roll rate at the time of steering supplied from the acceleration / deceleration / steering pitch / roll rate calculation section 673 .

[0130] The steering torque target control amount calculation unit 84 calculates the steering torque target control amount by referring to the steering torque signal indicated by the steering torque signal. The steering torque speed calculation unit 85 calculates the steering torque speed by referring to the time change of the steering torque indicated by the steering torque signal. The steering torque speed target control amount calculation unit 86 calculates the steering torque speed target control amount by referring to the steering torque speed calculated by the steering torque speed calculation unit 85 for each of the four wheels of the vehicle 900.

[0131] In this way, both the steering torque target control amount operation unit 84 and the steering torque speed target control amount calculation unit 86 directly or indirectly refer to the steering torque signal to calculate the target control amount, so that the roll of the vehicle 900 is suppressed and the posture of the vehicle 900 becomes closer to flat.

[0132] The steering torque-derived target controlled variable selection unit 87 selects a target controlled variable having a higher value between the steering torque target controlled variable and the steering torque speed target controlled variable as the steering torque-derived target controlled variable.

[0133] The roll attitude-derived target control variable selection unit 88 selects the target control variable with the highest value among the steering angle target control variable, the steering angular velocity target control variable, the roll rate target control variable, and the steering torque-derived target control variable as the roll attitude-derived target control variable. In this embodiment, the control until the roll attitude-derived target control variable is selected by the roll attitude-derived target control variable selection unit 88 when calculating the suspension control variable is also referred to as "steering torque response control."

[0134] (Roll attitude target control amount calculation unit)

[0135] Figure 4 1 is a block diagram showing an example of the functional configuration of the roll attitude target control amount calculation section 89 according to the present embodiment. Figure 4 As shown, the roll attitude target control amount calculation unit 89 includes a target pitch angle calculation unit 891 , a subtraction unit 892 , a pitch moment calculation unit 893 and a target control amount calculation unit 894 .

[0136] The target pitch angle calculation unit 891 calculates the target pitch angle with reference to the roll angle signal. Figure 5 891 according to the present embodiment. For example, the target pitch angle calculation unit 891 includes an absolute value operation unit 91 and a gain multiplication unit 92. Figure 5 The absolute value operation section 91 calculates the absolute value of the roll angle indicated by the roll angle signal and supplies the calculated absolute value to the gain multiplication section 92. The gain multiplication section 92 calculates the target pitch angle by multiplying the absolute value of the roll angle supplied from the absolute value operation section 91 by a gain.

[0137] like Figure 4 As shown, the roll attitude target control amount calculation unit 89 further calculates the target control amount with reference to the actual pitch angle. More specifically, the roll attitude target control amount calculation unit 89 calculates the target control amount based on the difference between the target pitch angle and the actual pitch angle.

[0138] The subtraction section 892 calculates a difference obtained by subtracting the actual pitch angle from the target pitch angle calculated by the target pitch angle calculation section 891 .

[0139] Pitch moment calculation unit 893 calculates the pitch moment of vehicle 900 based on the pitch angle difference calculated by subtraction unit 892. By calculating the pitch moment of vehicle 900 based on the pitch angle difference, a more appropriate pitch moment can be calculated from the perspective of attitude control, compared to when the pitch moment is calculated without reference to the actual pitch angle.

[0140] The target control amount calculation unit 894 calculates the target control amount by referring to the pitch moment calculated by the pitch moment calculation unit 893 and the roll attitude target control amount selected by the roll attitude target control amount selection unit 88. The target control amount obtained by this calculation serves as the roll attitude target control amount and as the output value of the roll attitude control unit 682.

[0141] Here, when the roll attitude-derived target control quantity is the steering torque-derived target control quantity, for example, the target control quantity calculation unit 894 receives the steering torque-derived target control quantity as the roll attitude-derived target control quantity, and adds the pitch moment to the received steering torque-derived target control quantity to calculate the roll attitude target control quantity.

[0142] As described above, the steering torque-derived target control variable is a control variable obtained by referencing the steering torque signal. Furthermore, the roll attitude target control variable is a target control variable referenced when controlling the suspension damping force. In this manner, the target control variable calculation unit 894 calculates the target control variable by referring to the steering torque signal and the target pitch angle. For example, the target control variable calculation unit 894 can calculate the roll attitude target control variable by referring to the steering torque-derived target control variable and the target pitch angle obtained based on the steering torque signal.

[0143] In this embodiment, the following control is also referred to as "steering torque reference control": the roll attitude derived target control amount is the steering torque derived target control amount, and the roll attitude derived target control amount is calculated with reference to the roll attitude derived target control amount and the pitch moment.

[0144] Here, the suspension control according to the present embodiment will be described more specifically from the perspective of the driver's steering.

[0145] First, when the driver turns the steering member 410, a steering torque is generated, and a steering torque signal is generated by the driver's turning operation of the steering member 410. The wheels 300A and 300B are turned to have a steering angle according to the generated steering torque signal, and the vehicle 900 turns according to the steering angle.

[0146] When vehicle 900 turns, rolling motion generates a damping force based on the displacement velocity of the shock absorbers (front and rear), and a force that pushes the axle downward is generated based on the difference between the damping force on the extension side and the damping force on the contraction side. Furthermore, a pitching moment is generated due to the difference in damping force between the front and rear wheels. Therefore, when vehicle 900 turns, a combination of rolling and pitching motion occurs in vehicle 900. As described above, the motion of vehicle 900 is detected as various state quantities by the various sensors described above. As described above, the detection results are input to CAN input unit 660 and used to control the operation of suspension device 100.

[0147] In this embodiment, control can be performed to further improve the cornering feel by referring to the roll angle and pitch angle. For example, the suspension is controlled so that the time difference between the peak of the roll angle and the peak of the pitch angle in vehicle 900 is small. This control allows the driver of vehicle 900 to experience a good cornering feel.

[0148] More specifically, the target control amount calculation unit 894 refers to the roll angle of the vehicle 900 and the pitch moment calculated by the pitch moment calculation unit 893. The target control amount calculation unit 894 then calculates a roll attitude target control amount that generates a difference between the phase of the roll angle in the vehicle 900 and the phase of the pitch angle obtained from the pitch moment.

[0149] Here, when calculating the roll attitude target control amount by target control amount calculation unit 894, the difference between the roll angle phase and the pitch angle phase can be appropriately set within a sufficiently small range to provide the driver with a good turning feel. From the perspective of ensuring a good turning feel for the driver, a smaller difference is more preferable. For example, it is preferably less than 1 / 4 cycle, more preferably less than 1 / 8 cycle, and most preferably zero. The "cycle" can be either the roll angle cycle or the pitch angle cycle, but from the perspective described above, the "cycle" is preferably the smaller of the roll angle cycle and the pitch angle cycle.

[0150] Figure 6 : is a diagram showing an example in which the time difference between the peak values of the roll angle and the pitch angle of the vehicle 900 is small. Figure 6 The phase difference shown in allows the driver of vehicle 900 to generally experience a good cornering feel. The time difference between the peaks is the time difference between the peaks of the roll angle and the pitch angle, which are closest to each other on the time axis. This time difference is called the phase difference, and when the time difference is zero, the roll angle and pitch angle are said to be synchronized.

[0151] The target control amount calculation unit 894 calculates a roll attitude target control amount sufficient to minimize the phase difference between the roll angle and the pitch angle. Then, with reference to the calculated roll attitude target control amount, the target control amount is calculated based on the roll attitude derived target control amount selected by the roll attitude derived target control amount selection unit 88. For example, the target control amount calculation unit 894 calculates the roll attitude target control amount by adding the aforementioned roll attitude target control amount to the roll attitude derived target control amount selected by the roll attitude derived target control amount selection unit 88. This control method of minimizing the phase difference between the roll angle and the pitch angle based on the pitch moment is also referred to as "phase difference reference control."

[0152] When the time difference between the peak values of the roll angle and the pitch angle of the vehicle 900 is large, the driver of the vehicle 900 generally cannot obtain a good turning feeling. Figure 7 : is a diagram showing an example in which the time difference between the peak values of the roll angle and the pitch angle of the vehicle 900 is large. Figure 7 , the driver of the vehicle 900 may feel some discomfort between, for example, the steering performed by himself or herself and the turning feeling obtained thereby. Even when the roll attitude target control amount calculated based on the difference between the phase of the roll angle and the phase of the pitch angle is added to the roll attitude derived target control amount selected by the roll attitude derived target control amount selection section 88, the driver of the vehicle 900 cannot obtain a good turning feeling.

[0153] (Effect of steering torque response control operation)

[0154] In this embodiment, the steering torque-derived target control variable selection unit 87 selects the target control variable with the higher value from among the steering torque target control variable and the steering torque speed target control variable as the steering torque-derived target control variable. Generally, there is a tendency for the signal to rise earlier at the torque speed, which is the time variation of the torque, than at the torque indicated by the steering torque signal. Similarly, there is a tendency for the signal to rise earlier at the steering angular velocity, which is the time variation of the steering angle, than at the steering angle indicated by the steering angle signal. The roll attitude-derived target control variable selection unit 88 then selects the target control variable with the higher value from among the steering angle target control variable, the steering angular speed target control variable, the roll rate target control variable, and the steering torque-derived target control variable as the roll attitude-derived target control variable. Therefore, according to this embodiment, more appropriate suspension control that responds quickly to changes in steering conditions can be implemented.

[0155] Furthermore, since the roll attitude control unit 682 calculates the roll attitude-derived target control amount as a candidate for the suspension control amount with reference to the steering torque signal and the steering angle signal, the damping force of the suspension can be appropriately controlled according to the steering condition.

[0156] In addition, the roll attitude control unit 682 can calculate the target control amount from the steering torque so that the damping force of the suspension on the side opposite to the steering direction is large. In this case, good ride comfort and stability of the vehicle 900 can be achieved according to the steering conditions.

[0157] (Operational effect of phase difference reference control)

[0158] When vehicle 900 turns, a combination of roll and pitch motion occurs. In this case, the gain characteristics of the pitch angle relative to the roll angle can be adjusted by appropriately setting the damping force differences between the left and right sides, and between the front and rear. Furthermore, by appropriately setting the roll rate and shock absorber displacement speed, the phase difference between the pitch angle and the roll angle can be adjusted. Furthermore, by optimally setting or controlling the phases of these motions, the driver's turning feel can be improved, making it easier to identify the driver's behavior with vehicle 900. Turning feel is the driver's perception of changes in vehicle behavior through their five senses.

[0159] According to this embodiment, the damping characteristics of the front and rear wheel shock absorbers are set to minimize the phase difference between the roll angle cycle and the pitch angle cycle. As a result, the phase of the combined roll and pitch motions in vehicle 900 is optimized, achieving a vehicle behavior that exhibits a sense of consistency between the roll and pitch motions during transient motion. Consequently, the driver's driving burden can be reduced.

[0160] (Operational effect of steering torque reference control)

[0161] As described above, when the driver uses the steering member 410 to steer the vehicle 900, a steering torque is generated at the start of steering, and a steering torque signal is generated. The roll attitude target control amount calculation unit 89 references the generated steering torque signal as the steering torque-derived target control amount. The target control amount calculation unit 894 calculates the roll attitude target control amount by referring to the roll attitude-derived target control amount selected by the roll attitude-derived target control amount selection unit 88 and the pitch moment.

[0162] According to this embodiment, when a steering torque signal is detected, a roll posture target control variable is prepared as a target control variable to improve the driver's turning feel. Therefore, in this embodiment, before the driver actually begins steering with steering member 410 and vehicle 900 performs a turning motion, the roll posture target control variable is prepared and used for suspension control. As the steering amount of steering member 410 increases, the suspension control effect generated by the roll posture target control variable becomes stronger.

[0163] The roll attitude target control amount begins to increase from the time the steering torque is generated. As described above, in this embodiment, the suspension is controlled to improve the driver's turning feel from the moment the steering member 410 is turned. Therefore, the driver's turning feel is improved from the start of the steering operation of the steering member 410, and the driver's sense of alignment with the vehicle 900 is further enhanced.

[0164] When controlling the vehicle 900's state to enhance the driver's turning feel, such as when detecting the occurrence of a roll motion of the vehicle 900 caused by the initiation of a turning motion, suspension control using the roll attitude target control amount substantially takes effect after a predetermined time has elapsed since the driver initiated the steering operation of the steering member 410. Therefore, when controlling the vehicle 900's state to enhance the driver's turning feel, the driver's improved turning feel is enhanced after the rotational motion of the steering member 410 begins to be substantially reflected in the behavior of the vehicle 900. However, the suspension control that enhances the turning feel is not reflected in the period between the rotational motion and the improvement in the turning feel, and during this period, the driver's sense of alignment with the vehicle 900 is not enhanced.

[0165] As is clear from the above description, it can be said that the present embodiment is a manner in which the roll posture target control amount is always calculated and another target control amount derived from the steering torque is always added.

[0166] Typically, after a steering torque is input, a yaw motion is generated in the vehicle, followed by a roll motion and a pitch motion. In this embodiment, the roll attitude target control amount is calculated using the steering torque calculated using the driver's steering, which is faster than the roll-related value or pitch-related value indicating the vehicle's behavior. Therefore, compared to the case where the roll attitude is controlled based on the roll-related value or pitch-related value indicating the vehicle's behavior, control that enhances the driver's turning feel can be reflected more quickly, specifically, almost at the same time that the steering torque input begins to be reflected in the vehicle's behavior. As described above, in this embodiment, the roll and pitch of the vehicle can be synchronized by controlling the suspension, and the driver's sense of unity of vehicle 900 can be enhanced.

[0167] [Second embodiment]

[0168] Another embodiment of the present invention will be described below. For ease of explanation, components having the same functions as those described in the above embodiment are given the same reference numerals, and their description will not be repeated.

[0169] The present embodiment differs from the first embodiment in that a target pitch angle calculation unit 991 is provided instead of the target pitch angle calculation unit 891 . Figure 8 Target pitch angle calculation unit 991 is a block diagram illustrating an example of the functional configuration of target pitch angle calculation unit 991 according to this embodiment. Target pitch angle calculation unit 991 includes a gain multiplication unit 95 instead of gain multiplication unit 92. Target pitch angle calculation unit 991 also includes a gain setting unit 96. In these respects, target pitch angle calculation unit 991 differs from target pitch angle calculation unit 891 in the first embodiment. Gain multiplication unit 92 and gain setting unit 96 form a gain changing unit.

[0170] Gain setting unit 96 sets a gain value by referring to a lateral G signal indicating the lateral acceleration of vehicle 900 and a longitudinal G signal indicating the longitudinal acceleration of vehicle 900. Gain multiplication unit 95 refers to the gain value set by gain setting unit 96 and changes the multiplication gain in accordance with the gain value. Gain multiplication unit 95 then calculates a target pitch angle by multiplying the absolute value of the roll angle calculated by absolute value calculation unit 91 by the changed gain.

[0171] When the road surface is uneven, the unevenness causes the lateral G and the longitudinal G of the vehicle 900 to fluctuate directly or indirectly due to the steering torque, etc. Therefore, from the perspective of performing suspension control that appropriately reflects the road surface conditions, it is advantageous to refer to the lateral G and the longitudinal G of the vehicle 900 to calculate the target pitch angle.

[0172] [Third embodiment]

[0173] For the sake of convenience, components having the same functions as those described in the above embodiments are given the same reference numerals, and their description will not be repeated.

[0174] This embodiment is the same as the above-mentioned first embodiment, except that the roll posture control unit 682 does not include the steering torque target control quantity calculation unit 84, the steering torque speed calculation unit 85, the steering torque speed target control quantity calculation unit 86 and the steering torque derived target control quantity selection unit 87, and the target control quantity calculation unit 894 in the roll posture control quantity calculation unit 89 is configured to reference the steering torque signal. Figure 9 : is a block diagram showing an example of the functional configuration of the roll attitude target control amount calculation section 89 according to the third embodiment of the present invention.

[0175] Target control variable calculation unit 894 references the roll attitude target control variable and pitch moment, and also references the steering torque signal. For example, target control variable calculation unit 894 calculates a first target control variable based on the roll attitude target control variable and pitch moment. Target control variable calculation unit 894 then calculates a second target control variable by correcting the first target control variable with reference to the steering torque signal. Target control variable calculation unit 894 then outputs the calculated second target control variable as the roll attitude target control variable.

[0176] For example, correction of the target control value with reference to the steering torque signal is performed as follows. The target control amount operation unit 894 sets a gain value with reference to the steering torque signal. For example, when the value of the steering torque signal (for example, the amount of displacement per unit time) is large, the gain value also increases accordingly. The target control amount operation unit 894 changes the gain to be multiplied according to the gain value, and multiplies the changed gain by the first target control amount to calculate the second target control amount. The gain can be multiplied by the target control amount derived from the roll attitude before calculating the first target control amount, or it can be multiplied by the pitch moment, or the gain can be multiplied by both the target control amount derived from the roll attitude and the pitch moment.

[0177] Alternatively, in this embodiment, a threshold value for the steering torque signal may be set. For example, when the steering torque signal exceeds the threshold value, the target control amount calculation unit 894 may perform a process of adding the pitch moment to the target control amount derived from the roll attitude, or may perform a process of multiplying the steering torque signal by a gain.

[0178] According to this embodiment, steering torque reference control can be executed according to the driver's steering operation. For example, stronger steering torque reference control can be executed compared to stronger steering operations. This is more effective from the perspective of providing the driver with a sense of alignment with vehicle 900 that matches the driver's turning experience.

[0179] In this embodiment, in addition to referencing the steering torque signal, other state quantities of vehicle 900 may also be referenced. For example, in this embodiment, in addition to the steering torque signal, the lateral G signal and the longitudinal G signal of vehicle 900 may also be referenced. The lateral G signal and the longitudinal G signal may be referenced in calculating the first target control variable or the second target control variable in the same manner as in the second embodiment described above. By further referencing these other state quantities, in addition to the aforementioned effects of this embodiment, the effects of the second embodiment described above can be further demonstrated.

[0180] [Example implemented by software]

[0181] The control blocks of the vehicle 900 (eg, the roll attitude target control amount calculation section 89 ) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

[0182] In the latter case, vehicle 900 is equipped with a computer that executes instructions from a program, which is software that implements each function. The computer includes, for example, one or more processors and a computer-readable recording medium storing the program. The processor in the computer then reads the program from the recording medium and executes it, thereby achieving the objectives of the present invention.

[0183] As a processor, for example, a central processing unit (CPU) can be used. As a recording medium, a "non-transitory tangible medium" such as a read-only memory (ROM), a magnetic tape, a disk, a card, a semiconductor memory, a programmable logic circuit, etc. can be used. A random access memory (RAM) for loading programs can also be provided.

[0184] Furthermore, the above program can be provided to a computer via any transmission medium capable of transmitting the program (communication network, broadcast wave, etc.). One aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave, wherein the above program is implemented by electronic transmission.

[0185] [Additional Notes]

[0186] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. In addition, the technical scope of the present invention includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

[0187] For example, in the above-described embodiment, when referring to the steering torque signal, a threshold value for the steering torque signal can be set. For example, a steering torque signal generated by any amount of movement greater than the set play in steering member 410 can be used as the threshold value. With this configuration, since control in this embodiment is executed when the driver is actually steering steering member 410, the occurrence of excessive control in this embodiment can be suppressed.

[0188] Furthermore, in the above-described embodiment, the ECU 600 may be configured to select a specific target control variable as the roll attitude-derived target control variable based on the type of state variable to be acquired for the vehicle 900. For example, when the ECU 600 receives a steering torque signal, the roll attitude-derived target control variable selection unit 88 may be configured to select the steering torque-derived target control variable as the roll attitude-derived target control variable based on the steering torque signal.

[0189] For example, depending on road conditions, better ride comfort can often be achieved by outputting a target control variable derived from a steering angle signal rather than a steering torque signal. By employing a configuration that selects a specific target control variable as the roll attitude-derived target control variable based on the type of vehicle state variable to be acquired, a more appropriate target control variable can be output based on the road conditions and the driver's intent. Consequently, this configuration achieves better ride comfort.

[0190] In the above-described embodiment, the control for enhancing the turning feel is not limited to reducing the phase difference between the roll angle and the pitch angle. For example, it is known that the driver's turning feel can be enhanced by appropriately controlling the relationship between the roll angle and the pitch angle, in addition to the phase difference. In the above-described embodiment, the roll attitude target control amount can be calculated so as to maintain this relationship between the roll angle and the pitch angle.

[0191] For example, it is known that the driver's cornering experience can be improved by setting the vehicle's front-to-rear tilt during roll to a lowered front position, regardless of cornering acceleration. In this case, the relationship between the roll angle and the pitch angle is expressed by the following equation. In this equation, θ is the pitch angle, and φ is the roll angle. In the following equation, a lowered front pitch angle is considered positive.

[0192] θ ≥ 0 (where φ ≠ 0)

[0193] In addition, it is known that when there is always no phase difference between the roll angle and the pitch angle of the vehicle during rolling, the turning feeling is improved. In this case, the roll angle and the pitch angle are considered to be in a proportional relationship and are expressed by the following formula. In the formula, k rp is the proportionality constant.

[0194] θ=k rp φ

[0195] It is also known that a constant ratio of the roll rate to the pitch rate improves cornering feel. In this case, the ratio of the roll rate to the pitch rate is expressed by the following equation: In the equation, the dotted θ represents the pitch rate, and the dotted φ represents the roll rate.

[0196]

[0197] Furthermore, in the above-described embodiment, the roll attitude target control amount calculation unit 89 can calculate the roll attitude target control amount by referring to the roll angle and the target pitch angle calculated by the target pitch angle calculation unit 891, rather than the actual pitch angle. This configuration can further reduce the control burden for calculating the roll attitude target control amount.

[0198] In the above-described embodiment, the state quantities of the vehicle 900 may be measurement values (actual measurement values) or estimated values of various sensors.

[0199] Furthermore, in the above-described embodiment, as long as the effects of this embodiment can be achieved, other controls for enhancing the driver's turning experience can be executed in parallel. For example, to optimize the phase of the combined roll and pitch motions, the following control can be added to the above-described suspension control: when vehicle 900 rolls, the difference between the extension-side damping force and the contraction-side damping force in the front wheel shock absorber is set to be greater than the difference between the extension-side damping force and the contraction-side damping force in the rear wheel shock absorber.

[0200] Furthermore, in the second embodiment described above, one or both of the lateral G and the front-rear G may be used as the gain changing portion. Furthermore, the gain value may be set based on state quantities other than the lateral G and the front-rear G.

[0201] Alternatively, in the second embodiment described above, specific controls based on the state of vehicle 900 may be executed in parallel as long as the effects of this embodiment can be achieved. For example, in a motion range where comfort regarding roll during cornering is important, such as a motion range where the lateral acceleration is 0.2 G (G represents the acceleration due to gravity) or within a predetermined range including 0.2 G, the damping coefficients of the front and rear wheel shock absorbers relative to the suspension stroke speed may be increased linearly from the contraction side to the extension side. Alternatively, the linear increase may be approximated by a stepwise increase to increase the damping coefficient in the motion range. [Summary of the invention]

[0203] A suspension control device according to an embodiment of the present invention controls the damping force of a suspension. The suspension control device includes: a target pitch angle calculation unit (891) that calculates a target pitch angle with reference to a roll angle signal; and a target control amount calculation unit (e.g., a target control amount calculation unit 894) that calculates a target roll attitude control amount to be used when controlling the damping force of the suspension with reference to a steering torque signal and the target pitch angle. This configuration enables suspension control that synchronizes the roll and pitch of a vehicle. Therefore, the above configuration enhances the driver's sense of alignment with the vehicle.

[0204] The target control variable calculation unit can calculate the roll attitude target control variable by reference to the steering torque-derived target control variable, which is obtained by reference to the steering torque signal and the target pitch angle. This configuration allows the steering torque signal to be used as a reference when calculating the roll attitude target control variable, rather than as a reference to the steering torque signal when calculating the roll attitude target control variable. This prevents duplication of processing related to the reference steering torque signal. Therefore, this configuration is even more effective in terms of implementing suspension control that rapidly responds to changes in steering conditions.

[0205] The target control amount calculation unit can further calculate the target control amount based on the actual pitch angle. This configuration allows the roll attitude target control amount to be calculated based on a pitch angle that does not overlap with the actual pitch angle. Therefore, this configuration is more effective from the perspective of improving the accuracy of controlling the suspension damping force and enhancing the driver's cornering experience. Furthermore, the target control amount calculation unit can calculate the target control amount based on the difference between the target pitch angle and the actual pitch angle. From this perspective, this configuration is even more effective.

[0206] The target pitch angle calculation unit may include a gain multiplication unit that calculates the target pitch angle by multiplying the roll angle signal by a gain. According to this configuration, the target pitch angle can be easily calculated by using the relationship between the roll angle and the pitch angle, which is more effective from the perspective of suppressing an increase in the control burden.

[0207] The target pitch angle calculation unit may include a first gain changing unit that changes the gain value based on lateral acceleration. Alternatively, the target pitch angle calculation unit may include a second gain changing unit that changes the gain value based on longitudinal acceleration. These configurations are even more effective in controlling the suspension from the perspective of appropriately reflecting road conditions.

[0208] A suspension device according to an embodiment of the present invention includes a suspension (suspension device 100) and a control unit (ECU 600) that controls the suspension's damping force. Furthermore, the control unit includes a target pitch angle calculation unit that calculates a target pitch angle based on a roll angle signal, and a target control variable calculation unit that calculates a target control variable used in controlling the suspension's damping force based on a steering torque signal and the target pitch angle. This configuration enables suspension control that synchronizes the roll and pitch of the vehicle, thereby enhancing the driver's sense of alignment with the vehicle.

Claims

1. A suspension control device, configured to control a damping force of a suspension, the suspension control device comprising: a target pitch angle calculation unit configured to calculate a target pitch angle with reference to the roll angle signal; as well as a target control amount calculation unit configured to calculate a target control amount by adding a steering torque-derived target control amount to a pitching moment, the target control amount being a target control amount referenced when controlling the damping force of the suspension, the steering torque-derived target control amount being obtained by referring to a steering torque signal, and the pitching moment being calculated based on a difference between the target pitch angle and an actual pitch angle, wherein The target pitch angle calculation section includes a gain multiplication section configured to calculate the target pitch angle by multiplying the roll angle signal by a gain, and The target pitch angle calculation section includes a first gain changing section configured to change a value of the gain with reference to a lateral acceleration.

2. The suspension control device according to claim 1, wherein: The target control amount calculation section is configured to calculate the target control amount further with reference to the actual pitch angle.

3. The suspension control device according to claim 2, wherein: The target control amount calculation section is configured to calculate the target control amount based on the difference between the target pitch angle and the actual pitch angle.

4. The suspension control device according to claim 1, wherein: The target pitch angle calculation section includes a second gain changing section configured to change a value of the gain with reference to a longitudinal acceleration.

5. The suspension control device according to claim 1, wherein: The target pitch angle calculation section includes a second gain changing section configured to change a value of the gain with reference to a longitudinal acceleration.

6. A suspension device comprising: suspension; and A control unit configured to control the damping force of the suspension, wherein: The control unit includes a target pitch angle calculation unit configured to calculate a target pitch angle with reference to the roll angle signal; as well as a target control amount calculation unit configured to calculate a target control amount by adding a steering torque-derived target control amount to a pitching moment, the target control amount being a target control amount referenced when controlling the damping force of the suspension, the steering torque-derived target control amount being obtained by referring to a steering torque signal, and the pitching moment being calculated based on a difference between the target pitch angle and an actual pitch angle, The target pitch angle calculation section includes a gain multiplication section configured to calculate the target pitch angle by multiplying the roll angle signal by a gain, and The target pitch angle calculation section includes a first gain changing section configured to change a value of the gain with reference to a lateral acceleration.

Images