JP2020001692A - Rack shaft force estimation device - Google Patents

Abstract

To apply assist torque or reaction force torque with less discomfort for a driver.SOLUTION: An ECU (600) includes a rack shaft force estimation unit (620) for estimating rack shaft force by referring to a roll rate of a vehicle body.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rack axial force estimation device.

  2. Description of the Related Art A steering device that applies an assist torque or a reaction torque to a steering member is known. Further, in a steering device, a technique of estimating a rack axial force at the time of turning a tire from a steering angle and a vehicle speed is known (Patent Document 1).

JP 2010-100799 A (published May 6, 2010)

  In the control device that applies the assist torque or the reaction torque to the steering member, it is preferable to apply the assist torque or the reaction torque that is less uncomfortable for the driver of the vehicle to the steering member.

  For this purpose, it is preferable to appropriately identify a roll change in a transient state of the vehicle body. An object of the present invention is to appropriately identify a roll change in a transient state of a vehicle body in a control device that applies an assist torque or a reaction torque to a steering member.

  For this purpose, the present invention is a rack axial force estimating apparatus that calculates an estimated value of a suspension damping force with reference to a roll rate of a vehicle body and estimates a rack axial force from the estimated value of the suspension damping force. .

  According to the present invention, a roll change in a transient state of a vehicle body can be suitably identified.

FIG. 1 is a diagram illustrating a schematic configuration of a vehicle according to a first embodiment of the present invention. FIG. 1 is a block diagram illustrating a schematic configuration of an ECU according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration example of a steering control unit according to the first embodiment of the present invention. It is a figure which shows the mechanism regarding the change of the vehicle motion at the time of roll motion generation, (a) shows the vehicle state at the time of going straight, (b) shows the vehicle state at the time of turning roll, (c) is the roll angle And the relationship between the suspension stroke. It is a figure which shows the mechanism regarding the change of the force at the time of roll movement generation, (a) shows the relationship between a cornering force and a tire lateral force, (b) shows the relationship of a rack axial force. FIG. 2 is a block diagram illustrating a configuration example of a suspension control unit according to the first embodiment of the present invention. It is a block diagram showing an example of composition of a steering control part concerning Embodiment 2 of the present invention. It is a block diagram showing an example of composition of a steering control part concerning Embodiment 3 of the present invention.

[Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described in detail.

(Configuration of Vehicle 900)
FIG. 1 is a diagram illustrating a schematic configuration of a vehicle 900 according to the present embodiment. As shown in FIG. 1, a vehicle 900 includes a 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 application unit 460, and a rack. It includes a pinion mechanism 470, a rack shaft 480, an engine 500, an ECU (Electronic Control Unit) (control device) 600, a power generator 700, and a battery 800.

  The wheel 300 on which the tire 310 is mounted is suspended on the vehicle body 200 by the suspension device 100. Since the vehicle 900 is a four-wheeled vehicle, four suspension devices 100, four wheels 300, and three tires 310 are provided.

  The tires and wheels of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are referred to as a tire 310A and a wheel 300A, a tire 310B and a wheel 300B, a tire 310C and a wheel 300C, and a tire 310D and a wheel, respectively. Also referred to as 300D. Hereinafter, similarly, the configurations attached to the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are denoted by reference numerals “A”, “B”, “C”, and “D”. There is.

  The suspension device 100 includes a hydraulic shock absorber, an upper arm, and a lower arm. In addition, the hydraulic shock absorber includes a solenoid valve that is an electromagnetic valve that adjusts a damping force generated by the hydraulic shock absorber. However, this does not limit the present embodiment, and the hydraulic shock absorber may use an electromagnetic valve other than the solenoid valve as the electromagnetic valve for adjusting the damping force. For example, the electromagnetic valve may be configured to include an electromagnetic valve using an electromagnetic fluid (magnetic fluid).

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

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

  The rack and pinion mechanism 470 is a mechanism for converting rotation around the axis of the steering shaft 420 into displacement along 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.

  Torque sensor 430 detects a steering torque applied to steering shaft 420, in other words, a 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 provided inside steering shaft 420, and outputs the detection result as a torque sensor signal. As the torque sensor 430, a well-known sensor such as a Hall IC, an MR element, and a magnetostrictive torque sensor may be used.

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

  Torque application section 460 applies an assist torque or a reaction torque according to a steering control amount supplied from ECU 600 to steering shaft 420. The torque applying unit 460 includes a motor that generates an assist torque or a reaction torque according to the steering control amount, and a torque transmission mechanism that transmits the torque generated by the motor to the steering shaft 420.

  Note that specific examples of the “control amount” in this specification include a current value, a duty ratio, an attenuation rate, an attenuation ratio, and the like.

  The steering member 410, the steering shaft 420, the torque sensor 430, the steering angle sensor 440, the torque applying unit 460, the rack and pinion mechanism 470, the rack shaft 480, and the ECU 600 constitute a steering device according to the present embodiment.

  In the above description, “connected to transmit torque” refers to connection in which rotation of one member causes rotation of the other member to occur, for example, one member and the other member are connected to each other. Are integrally formed, one member is directly or indirectly fixed to one member, and one member and the other member are interlocked via a joint member or the like. This includes at least the case where the connection is made.

  Further, in the above example, the steering device in which the steering member 410 to the rack shaft 480 are always mechanically connected has been described as an example. However, this is not limited to the present embodiment, and the steering device according to the present embodiment is not limited thereto. The device may be, for example, a steer-by-wire steering device. The matters described below can also be applied to the steering device of the steer-by-wire system.

  The ECU 600 controls various electronic devices included in the vehicle 900. More specifically, ECU 600 controls the amount of assist torque or reaction torque applied to steering shaft 420 by adjusting the steering control amount supplied to torque application section 460.

  The ECU 600 controls the opening and closing of the solenoid valve by supplying a suspension control amount to a solenoid valve provided in the hydraulic shock absorber included in the suspension device 100. In order to enable this control, a power line for supplying drive power from the ECU 600 to the solenoid valve is provided.

  The vehicle 900 has a wheel speed sensor 320 that is provided for each wheel 300 and detects a wheel speed of each wheel 300, a lateral G sensor 330 that detects lateral acceleration of the vehicle 900, and detects a longitudinal acceleration of the vehicle 900. G sensor 340 for detecting the yaw rate of the vehicle 900, an engine torque sensor 510 for detecting the torque generated by the engine 500, an engine speed sensor 520 for detecting the rotation speed of the engine 500, and a brake device. A brake pressure sensor 530 for detecting the pressure applied to the brake fluid is provided. The detection results of these various sensors are supplied to the ECU 600.

  Note that vehicle 900 may further include a roll rate sensor that detects a roll rate of vehicle body 200 and a stroke sensor that detects a stroke of each suspension.

  Although not shown, the vehicle 900 includes an ABS (Antilock Brake System) which is a system for preventing wheel lock during braking, a TCS (Traction Control System) for suppressing wheel idling at the time of acceleration or the like, and The vehicle is provided with a brake device capable of controlling a vehicle stability (VSA), which is a vehicle behavior stabilization control system having an automatic braking function for turning yaw moment control and a brake assist function.

  Here, the ABS, TCS, and VSA compare the wheel speed determined according to the estimated vehicle speed with the wheel speed detected by the wheel speed sensor 320, and these two wheel speed values are set to predetermined values. If there is a difference, it is determined that the vehicle is in the slip state. The ABS, TCS, and VSA stabilize the behavior of the vehicle 900 by performing optimal brake control and traction control according to the running state of the vehicle 900 through such processing.

  The supply of the detection results by the various sensors described above to the ECU 600 and the transmission of control signals from the ECU 600 to each unit are performed via a CAN (Controller Area Network) 370.

(ECU 600)
Hereinafter, the ECU 600 will be specifically described with reference to different drawings. FIG. 2 is a diagram showing a schematic configuration of the ECU 600.

  The steering control unit 610 refers to various sensor detection results included in the CAN 370 and determines the magnitude of the steering control amount to be supplied to the torque application unit 460.

  In this specification, the expression “with reference to” may include meanings such as “using”, “considering”, and “dependent on”.

  The suspension control unit 650 refers to various sensor detection results included in the CAN 370 and determines the magnitude of the suspension control amount to be supplied to the solenoid valve included in the hydraulic shock absorber included in the suspension device 100.

  Further, as shown in FIG. 2, in the ECU 600, the suspension control amount calculated by the suspension control unit 650 is supplied to the steering control unit 610, and is referred to for determining the magnitude of the steering control amount.

  Note that the roll rate value may be configured to take “0” as a reference value when the inclination of the vehicle 900 does not change for a predetermined minute time, and the roll rate may be represented as a deviation from the reference value. .

  The process of “determining the magnitude of the control amount” includes the case where the magnitude of the control amount is set to zero, that is, the case where the control amount is not supplied.

  Further, the steering control unit 610 and the suspension control unit 650 may be configured as separate ECUs. In the case of such a configuration, the control described in this specification is realized by the steering control unit 610 and the suspension control unit 650 communicating with each other using a communication unit.

(Steering control unit)
Subsequently, the steering control unit 610 will be described more specifically with reference to FIG. FIG. 3 is a block diagram illustrating a configuration example of the steering control unit 610.

  As shown in FIG. 3, the steering control unit 610 includes a base control amount calculation unit 611, an axial force correction current calculation unit 612, a control amount correction unit 613, and a rack axial force estimation unit 620.

  The base control amount calculation unit 611 refers to a steering torque supplied from the torque sensor 430 and a vehicle speed determined according to the wheel speed detected by the wheel speed sensor 320, and controls the magnitude of the assist torque or the reaction torque. Control amount is calculated. The control amount calculated by the base control amount calculation unit 611 is corrected by the control amount correction unit 613 and then supplied to the torque application unit 460 as a steering control amount.

(Rack axial force estimator)
The rack axial force estimating unit 620 estimates the rack axial force with reference to the roll rate supplied from the roll rate sensor. The rack axial force estimating unit 620 includes a roll rate-related suspension damping force estimating unit 621 and a first constant gain applying unit 627 as shown in FIG. The roll rate-related suspension damping force estimating unit 621 and the first constant gain applying unit 627 are combined with the roll rate-related rack axial force estimating unit 628 (first rack axial force estimating unit in the claims). , Sometimes called.

The roll rate related suspension damping force estimating unit 621 estimates the damping force of the suspension according to the roll rate with reference to the roll rate map shown in FIG. This roll rate map is a map in which the roll rate is input and the estimated value of the suspension damping force according to the roll rate is output. In this roll rate map, the horizontal axis shows the roll rate, and the vertical axis shows the estimated value of the suspension damping force. In FIG. 3, Df _{1 to} Df ₃ indicate values of suspension control current as suspension control amounts. Df _{1 to} Df ₃ can be said to be values related to the attenuation coefficient.

  Here, the damping coefficient is a numerical value of a damping characteristic, which is a characteristic indicating a relationship between the stroke speed of the damper and the damping force, and the damping force is a resistance force when the hydraulic shock absorber is pushed and pulled. is there.

  As described above, the roll rate-related suspension damping force estimation unit 621 refers to a different roll rate map according to the value of the suspension control amount. The roll rate-related suspension damping force estimating unit 621 calculates an estimated value of the suspension damping force according to the roll rate based on the roll rate by referring to the roll rate map, and calculates the estimated value of the calculated suspension damping force. Output to the first constant gain application section 627. The first constant gain application unit 627 calculates and outputs an estimated rack axial force from the estimated value of the suspension damping force according to the roll rate.

  The first constant gain application section 627 applies a gain according to the vehicle 900 to the estimated value of the suspension damping force according to the roll rate. More specifically, the suspension estimation value supplied from the roll rate-related suspension damping force estimation unit 621 is multiplied by a correction coefficient corresponding to the vehicle 900. Examples of the correction coefficient according to the vehicle 900 include a gain according to the caster angle β, the knuckle length Lkn, the tread width TW, the center of gravity height Hg, and the like.

  Further, the rack axial force estimating unit 620 may further estimate the rack axial force according to the roll rate by further referring to the suspension control current. In this case, the roll rate map referred to by the roll rate-related suspension damping force estimating unit 621 is a map in which the roll rate and the suspension control current are input and the estimated value of the suspension damping force according to the roll rate is output. The roll rate-related suspension damping force estimating unit 621 refers to this roll rate map, and based on the roll rate supplied from the roll rate sensor and the suspension control current supplied from the suspension control unit 650, responds to the roll rate. The estimated value of the suspension damping force is calculated and output to the first constant gain applying unit 627. The first constant gain application unit 627 calculates and outputs an estimated rack axial force from the estimated value of the suspension damping force according to the roll rate.

  Here, the roll rate-related suspension damping force estimating unit 621 calculates and outputs a suspension damping force estimated value that is larger as the control current of the suspension is larger.

  That is, the rack axial force estimating unit 620 can calculate and output the estimated rack axial force as the control current of the suspension increases.

  The axial force correction current calculation unit 612 calculates the value of the correction current according to the rack axial force estimated by the rack axial force estimation unit 620.

  The control amount correction unit 613 generates a steering control amount by correcting the control amount calculated by the base control amount calculation unit 611 with the correction current supplied from the axial force correction current calculation unit 612. In other words, the control amount correction unit 613 corrects the control amount calculated by the base control amount calculation unit 611 with reference to the rack axial force estimated by the rack axial force estimation unit 620.

  As described above, the control amount correcting unit 613 corrects the control amount calculated by the base control amount calculating unit 611 with reference to the rack axial force estimated by the rack axial force estimating unit 620, so that the driver feels uncomfortable. It is possible to apply the assist torque or the reaction torque with less force to the steering member 410.

  Further, the steering control unit 610 according to the present embodiment can estimate the rolling direction of the vehicle body 200 by estimating the rack axial force with reference to the roll rate of the vehicle body 200. Roll changes during transients can be identified. As described above, the control amount correction unit 613 corrects the control amount calculated by the base control amount calculation unit 611 in accordance with the roll change in the transient state of the vehicle body 200, so that the assist torque or the counter torque with little discomfort for the driver is provided. A force torque can be applied to the steering member 410.

(Calculation method of estimated rack axial force)
Subsequently, a method of calculating the estimated rack axial force will be described more specifically with reference to FIGS. First, with reference to FIG. 4, a mechanism from the viewpoint of a change in vehicle motion when a roll motion occurs will be described.

  4A and 4B are diagrams illustrating a mechanism relating to a change in vehicle motion when a roll motion occurs, wherein FIG. 4A illustrates a vehicle condition when traveling straight, FIG. 4B illustrates a vehicle condition when turning and turning, and FIG. The relationship between the roll angle and the suspension stroke is shown.

As shown in FIG. 4, in the vehicle state at the time of the turning roll, in other words, in the vehicle state of the vehicle 900 in which the driver operates the steering member 410, the tire cornering force, the lateral G, the centrifugal force, the roll moment, and the load movement are different. appear. Here, in FIG. 4, the height of the center of gravity of the vehicle 900 is Hg [m], the tread width of the vehicle 900 is TW [m], the total cornering force of the four wheels of the vehicle 900 is CF [kgf], and the inner ring side cornering of the vehicle 900 The force is CF _in [kgf], the outer ring side cornering force of the vehicle 900 is CF _out [kgf], the centrifugal force is F _cnt [kgf], the lateral G is Gy [G '], and the roll moment is M _roll [kgf · m]. The load movement is represented by ΔW [kgf], the roll angle is represented by θ _roll [deg], the inner wheel side stroke amount is represented by D _in [m], and the outer wheel side stroke amount is represented by D _out [m].

  As shown in FIG. 4 (b), the centrifugal force of the turning vehicle 900 and the tire cornering force are balanced, and are represented by the following equation (1).

  The roll moment is represented by the following equations (2) and (3).

By formulating the above equations (2) and (3) for M _roll , the following equation (4) is obtained.

  When the load distribution between the front wheel and the rear wheel is a: b, the load applied to each wheel is as follows.

W _car indicates the weight of the vehicle 900, _×× a × W _car and _×× a × W _car indicate the load in the 1G state, and -a × ΔW, -b × ΔW, a × ΔW and b × ΔW indicate the amount of load movement.

  As shown in FIG. 4C, the roll angle according to the stroke of the suspension 100 on the inner and outer wheels is represented by the following equation (5).

  The relational expression between the load movement and the stroke amount is represented by the following expression (6). Expression (6) below represents a relational expression between the load movement on the front wheel side and the stroke amount.

DF _fr represents a front wheel damping coefficient [kgfs / m], and K _fr represents a front wheel spring coefficient [kgf / m].

  When the stroke amount of the expansion and the stroke amount of the contraction of the suspension 100 in the inner and outer wheels are equivalent to the left and right, it is expressed as the following equation (7).

Note that _Deq represents an equivalent stroke amount [m].

  The following equation (8) is obtained by applying the above equation (7) to the above equation (5) and approximating the trigonometric function to a straight line.

  Also, by applying the above equation (7) to the above equation (6), the following equation (9) is obtained.

In addition,

Indicates a roll rate.

Here, since the damping coefficient DF _fr is determined by the stroke speed and the current according to the damper characteristics, in the above equation (9),

To

Replace with In the above equation (9),

And rearranging the equations, the following equation (10) is obtained.

  By substituting the above equation (4) into the above equation (10), the following equation (11), which is a relational equation relating to a change in vehicle motion, can be obtained.

Next, with reference to FIG. 5, a mechanism from the viewpoint of a change in force when a roll motion occurs will be described. FIGS. 5A and 5B are diagrams showing a mechanism relating to a change in force when a roll motion occurs, wherein FIG. 5A shows a relationship between a cornering force and a tire lateral force, and FIG. 5B shows a relationship between a rack axial force. Here, in FIG. 5, the cornering force is CF [kgf], the tire lateral force _TF y [kgf], is slip angle alpha [°], the tire rolling resistance _TF x [kgf], pneumatic trail is _t p [ m], caster rail is t _c [m], caster angle is β [°], SAT moment (moment due to tire lateral force) is M _SAT [kgf · m], rack axial force is RF _SAT [kgf], knuckle length Is represented as L _kn [m]. Incidentally, pneumatic trail t _p decreases with slip angle α is larger than a predetermined value. This decrease in pneumatic trail _{t p,} SAT moment _{M SAT} is reduced.

  The relational expression of the cornering force, the tire lateral force, and the rolling resistance is represented by the following expression (12).

  Further, the SAT moment due to the tire lateral force around the kingpin axis is expressed by the following equation (13).

  Further, the rack axial force is represented by the following equation (14).

  The above equation (13) is substituted into the above equation (14). Here, the sideslip angle is small,

If it is,

The following equation (15), which is a relational equation relating to a change in force, can be obtained.

  The following equation (16) can be obtained by simultaneously rearranging the relational expressions of the above equation (11) and the above equation (15) for CF.

  By using the above equation (16), the rack axial force estimating unit 620 can input a roll rate, a roll angle, and a coefficient corresponding to the vehicle 900, and can output an estimated rack axial force. The estimated rack axial force related to the roll rate (the estimated rack axial force related to the roll rate, the first rack axial force in the claims) estimated by the roll rate related rack axial force estimating unit 628 is calculated by the above equation (16). At

Corresponding to Further, an estimated rack axial force related to the roll angle (a roll angle-related estimated rack axis) estimated by a roll angle-related rack axial force estimating unit 622 (a second rack axial force estimating unit in claims) described later in the second embodiment. Force, the first rack axial force in the claims) is the following equation (16):

Corresponding to Further, the correction coefficient determined by the trail map application unit 624 described later in the third embodiment is represented by the following equation (16).

Corresponding to Further, a correction coefficient determined by a second constant gain application unit 626 described later is calculated by using the above equation (16).

Corresponding to

(Suspension control unit)
Subsequently, the suspension control unit will be described with reference to FIG. FIG. 6 is a block diagram illustrating a configuration example of the suspension control unit 650.

  As shown in FIG. 6, 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.

  The CAN input unit 660 acquires various signals via the CAN 370. As shown in FIG. 6, the CAN input unit 660 acquires the following signals (parentheses indicate acquisition sources).

・ Four wheel speeds (wheel speed sensors 320A to 320D)
・ Yaw rate (Yaw rate sensor 350)
-Front and back G (front and back G sensor 340)
・ Horizontal G (horizontal G sensor 330)
・ Brake pressure (brake pressure sensor 530)
-Engine torque (engine torque sensor 510)
-Engine speed (engine speed sensor 520)
-Steering angle (steering angle sensor 440)
The vehicle state estimating unit 670 estimates the state of the vehicle 900 with reference to various signals acquired by the CAN input unit 660. The vehicle state estimating 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 turning, and the pitch rate during acceleration / deceleration as the estimation result.

  As shown in FIG. 6, the vehicle state estimating 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 one-wheel model application unit 674. It has.

  The acceleration / deceleration / steering correction amount calculation unit 671 refers to the yaw rate, the front / rear G, the wheel speeds of the four wheels, the brake pressure, the engine torque, and the engine speed, and refers to the vehicle front / rear speed, inner / outer wheel difference ratio, and adjustment. The gain is calculated, and the calculation result is supplied to the state estimation one-wheel model application unit 674.

  The acceleration / deceleration / steering pitch / roll rate calculation unit 673 refers to the longitudinal G and the lateral G, and calculates the turning roll rate and the acceleration / deceleration pitch rate. The calculation result is supplied to the state estimation one-wheel model application unit 674.

  In addition, the acceleration / deceleration / steering-time pitch / roll rate calculation unit 673 supplies the calculated steering-time roll rate to the steering control unit 610 as a roll rate value. The acceleration / deceleration / steering-time pitch / roll rate calculation unit 673 may be configured to further refer to the suspension control amount output from the control amount selection unit 690. Details of the acceleration / deceleration / steering-time pitch / roll rate calculation unit 673 will be described later with reference to another drawing.

  As described above, the acceleration / deceleration / steering-time pitch / roll rate calculating unit 673 supplies the steering-time roll rate calculated with reference to the longitudinal G and the lateral G to the steering control unit 610 as a roll rate value, and performs steering. The control unit 610 refers to the roll rate value and corrects the control amount for controlling the magnitude of the assist torque or the reaction torque, so that the steering control unit 610 more suitably adjusts the assist torque or the reaction torque. The size can be corrected.

  Further, as described above, if the acceleration / deceleration / steering-time pitch / roll rate calculation unit 673 is configured to further refer to the suspension control amount output from the control amount selection unit 690, the steering control unit 610 is more preferably used. The magnitude of the assist torque or the reaction torque can be corrected.

  The state estimation one-wheel model application unit 674 applies the state estimation one-wheel model to each wheel with reference to the calculation result by the acceleration / deceleration / steering correction amount calculation unit 671, and calculates the four-wheel sprung speed, The stroke speed, pitch rate, and roll rate of the four wheels are calculated. The calculation result is supplied to the steering stability / ride comfort control unit 680.

  The steering stability / ride comfort control unit 680 includes a skyhook control unit 681, a roll posture control unit 682, a pitch posture control unit 683, and an unsprung control unit 684.

  The skyhook control unit 681 performs ride comfort control (vibration suppression control) that suppresses the vehicle sway when overcoming road surface irregularities and enhances ride comfort. The skyhook control unit 681 determines the skyhook target control amount with reference to, for example, the sprung speed of the four wheels, the stroke speed, the pitch rate, and the roll rate of the four wheels, and uses the result as a control amount selection unit. 690.

  As a more specific example, the skyhook control unit 681 sets the damping force base value by referring to the sprung-damping force map based on the sprung speed. Further, the skyhook control unit 681 calculates the skyhook target damping force by multiplying the set damping force base value by the skyhook gain. Then, a skyhook target control amount is determined based on the skyhook target damping force and the stroke speed.

  The roll attitude control unit 682 performs roll attitude control with reference to the roll rate during steering and the steering angle, and controls the steering angle proportional target control amount, which is the target control amount according to the steering angle, and the target control according to the steering angular velocity. The control unit selects the steering angular velocity proportional target control amount as the amount and the roll rate proportional target control amount as the target control amount according to the roll rate, and supplies the result to the control amount selection unit 690.

  Further, the roll attitude control unit 682 may be configured to calculate the various target control amounts with reference to a steering torque signal indicating the steering torque. Here, the steering control unit 610 may supply a steering torque signal to the suspension control unit 650, and the steering control unit 610 may refer to the steering torque signal. It should be noted that the steering torque signal may be configured to use a phase-compensated signal. As a result, it is expected that a more comfortable ride can be realized.

  As described above, since the roll posture control unit 682 performs the roll posture control with reference to the turning roll rate calculated by the acceleration / deceleration / steering pitch / roll rate calculating unit 673, it is preferable to perform a suitable posture control. Can be. The turning roll rate calculated by the acceleration / deceleration / steering pitch / roll rate calculating unit 673 is not only the roll posture control by the roll posture control unit 682 but also the assist torque by the steering control unit 610 as described above. Alternatively, since it is also used for correcting the magnitude of the reaction torque, it is possible to provide an appropriate attitude control and a steering feeling without a sense of incongruity while suppressing an increase in the number of components.

  The pitch attitude control unit 683 performs pitch control with reference to the pitch rate during acceleration / deceleration, determines a pitch target control amount, and supplies the result to the control amount selection unit 690.

  The unsprung control section 684 performs unsprung vibration suppression control of the vehicle 900 with reference to the wheel speeds of the four wheels, and determines the unsprung vibration suppression control target control amount. The determination result is supplied to the control amount selection unit 690.

  The control amount selection unit 690 includes a skyhook target control amount, a steering angle proportional target control amount, a steering angular velocity proportional target control amount, a roll rate proportional target control amount, a pitch target control amount, and an unsprung vibration suppression control target control amount. The target control amount having the largest value is output as the suspension control amount.

  The damping characteristic of the hydraulic shock absorber changes based on the suspension control amount, and the damping force of the suspension is controlled.

(Modification)
The rack axial force estimating unit 620 according to the present embodiment replaces the roll rate supplied from the roll rate sensor with the roll rate output by the vehicle state estimating unit 670 of the suspension control unit 650, in other words, the damping force of the suspension. May be used as an input to the roll rate-related rack axial force estimating unit 628 as an estimated value referred to for calculating a control amount for controlling the roll rate.

  Further, the rack axial force estimating unit 620 according to the present embodiment sends the sensor value supplied from the stroke sensor to the roll rate related rack axial force estimating unit 628 instead of the suspension control current supplied from the suspension control unit 650. It may be used as an input. Here, in this specification, a value related to the damping coefficient, such as the suspension control current and the sensor value of the stroke sensor, is expressed as a damping coefficient related value.

  As described above, the rack axial force estimating unit 620 according to the present embodiment is configured to estimate the rack axial force using the roll rate and the damping coefficient related value. Since the rack axial force estimating unit 620 according to the present embodiment estimates the rack axial force using the roll rate and the damping coefficient related value, the rack axial force can be appropriately estimated.

[Embodiment 2]
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG.

  FIG. 7 is a block diagram illustrating a configuration example of the steering control unit according to the present embodiment. The steering control unit according to the present embodiment is configured such that the rack axial force estimating unit 620 further includes a roll angle related rack axial force estimating unit 622 and an adding unit 623 in the steering control unit 610 according to the first embodiment. In the following description, the same members as those already described are denoted by the same reference numerals, and description thereof will be omitted.

  Similar to the first embodiment, the roll rate-related rack axial force estimating unit 628 estimates the rack axial force with reference to the roll rate supplied from the roll rate sensor or the vehicle state estimating unit 670, and estimates the estimated rack axial force. Is supplied to the adding unit 623.

The roll angle-related rack axial force estimating unit 622 estimates the rack axial force with reference to the roll angle, and supplies the estimated roll angle-related estimated rack axial force to the adding unit 623. As a method of acquiring the roll angle, for example,
Integrating the roll rate supplied from the roll rate sensor and acquiring the integrated value as a roll angle;
Integrating the roll rate output by the vehicle state estimating unit 670, and acquiring the integrated value as the roll angle; and
-The vehicle 900 is provided with a roll angle sensor, and the roll angle is acquired from the roll angle sensor. The roll angle-related rack axial force estimating unit 622 includes, for example, a roll angle-related damping force estimating unit that estimates a damping force from a roll angle, and a gain corresponding to the estimated roll angle-related damping force estimated value according to the vehicle 900. And a third constant gain applying unit that multiplies the roll angle-related rack axial force estimating unit 622 according to the present embodiment. An example of the third constant gain application unit is an amplifier.

  The adding unit 623 adds the roll rate-related estimated rack axial force supplied from the roll rate-related rack axial force estimating unit 628 and the roll angle-related estimated rack axial force supplied from the roll angle-related rack axial force estimating unit 622. Then, a roll-related estimated rack axial force is calculated. The adding unit 623 adds the roll rate-related estimated rack axial force, which is the estimated rack axial force, and the roll angle-related estimated rack axial force, and calculates the estimated rack axial force. Therefore, it can be referred to as a roll-related rack axial force estimating unit (third rack axial force estimating unit in claims).

  As described above, the rack axial force estimating unit 620 according to the present embodiment further refers to the roll angle in addition to the roll rate and the damping coefficient-related value described above, and refers to the rack axial force related to the roll (the fourth embodiment). 3 rack axial force) can be estimated.

  The control amount correction unit 613 generates a steering control amount by correcting the control amount calculated by the base control amount calculation unit 611 with the correction current supplied from the axial force correction current calculation unit 612. In other words, the control amount correction unit 613 compares the control amount calculated by the base control amount calculation unit 611 with the roll-related estimated rack axial force (roll-rate-related estimated rack axial force and roll The estimated rack axial force obtained by adding the angle-related estimated rack axial force is corrected with reference to the estimated rack axial force.

  As described above, the control amount correcting unit 613 corrects the control amount calculated by the base control amount calculating unit 611 with reference to the roll-related estimated rack axial force calculated by the rack axial force estimating unit 620. It is possible to apply assist torque or reaction torque with less discomfort to the steering member 410 for the user.

[Embodiment 3]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.

FIG. 8 is a block diagram illustrating a configuration example of a steering control unit according to the present embodiment. In the steering control unit according to the present embodiment, in the steering control unit 610 according to the second embodiment, the rack axial force estimation unit 620 further includes a trail map application unit 624, a multiplication unit 625, and a second constant gain application unit 626. It is a configuration provided. Further, in the steering control unit 610 according to the second embodiment, the third constant gain applying unit in the roll angle related rack axial force estimating unit 622 is removed from the roll rate related rack axial force estimating unit 628 except for the first constant gain applying unit 627. (Amplifier) is excluded.
In the following description, the same members as those already described are denoted by the same reference numerals, and description thereof will be omitted.

  The trail map application unit 624 determines a correction coefficient with reference to the trail map as shown in FIG. Note that the trail map used in the trail map application unit 624 may be estimated from the side slip angle of the tire 310 or may be estimated using a conventional technique.

  The multiplication unit 625 applies a trail map to the roll-related estimated damping force (the estimated damping force obtained by adding the roll rate-related estimated damping force and the roll angle-related estimated damping force) supplied from the adding unit 623. The correction coefficient supplied from the unit 624 is multiplied.

  The second constant gain applying unit 626 calculates the estimated damping force supplied from the multiplying unit 625 (the estimated rack axial force obtained by multiplying the roll-related estimated rack axial force by the correction coefficient supplied from the trail map applying unit 624). Then, a gain according to the vehicle 900 is applied. More specifically, the estimated damping force supplied from multiplication unit 625 (the estimated damping force obtained by multiplying the roll-related estimated damping force by the correction coefficient supplied from trail map application unit 624) is applied to vehicle 900. The estimated rack axial force is calculated by multiplying by the corresponding correction coefficient. Examples of the correction coefficient according to the vehicle 900 include a gain according to the caster angle β, the knuckle length Lkn, the tread width TW, the height of the center of gravity Hg, and the like.

  In the present embodiment, the first constant gain applying unit 627 in the roll rate related rack axial force estimating unit 628 and the third constant gain applying unit in the roll angle related rack axial force estimating unit 622 according to the second embodiment are configured as a second unit. It is replaced by a constant gain application unit 626.

  Therefore, in the present embodiment, the roll rate-related rack damping force estimating section 621 and the second constant gain applying section 626 in the roll rate-related rack axial force estimating section 628 are combined to provide the roll rate-related rack axial force estimating section 628. In the roll angle-related rack axial force estimating unit 622, the roll angle-related damping force estimating unit and the second constant gain applying unit 626 are regarded as a roll angle-related rack axial force estimating unit 622. be able to.

  Therefore, this embodiment can be said to be a configuration for estimating the roll-related rack axial force from the roll rate-related rack axial force and the roll angle-related rack axial force.

  Here, the multiplying unit 625 and the second constant gain applying unit 626 are configured to multiply the estimated rack axial force supplied from the adding unit 623 by a correction coefficient according to the vehicle 900. , And / or the second constant gain application unit 626 is also referred to as a vehicle state coefficient multiplication unit.

  As described above, the rack axial force estimating unit 620 according to the present embodiment refers to the correction coefficient according to the vehicle 900 in addition to the above-described roll rate, the damping coefficient related value, and the roll angle, and calculates the rack axial force. Can be estimated.

  The control amount correction unit 613 generates a steering control amount by correcting the control amount calculated by the base control amount calculation unit 611 with the correction current supplied from the axial force correction current calculation unit 612. In other words, the control amount correction unit 613 compares the control amount calculated by the base control amount calculation unit 611 with the roll-related estimated rack axial force (roll-rate-related estimated rack axial force and roll The estimated rack axial force obtained by adding the angle-related estimated rack axial force) is corrected with reference to a correction coefficient corresponding to the vehicle 900.

  As described above, the control amount correction unit 613 compares the control amount calculated by the base control amount calculation unit 611 with the roll-related estimated rack axial force calculated by the rack axial force estimation unit 620 (the roll rate-related estimated rack axial force and the roll amount). The assist torque or the reaction torque with less discomfort for the driver by correcting with reference to the estimated rack axial force obtained by adding the angle-related estimated rack axial force) and the correction coefficient according to the vehicle 900. Can be applied to the steering member 410.

[Example of software implementation]
The control blocks (the steering control unit 610 and the suspension control unit 650) of the ECU 600 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or by using a CPU (Central Processing Unit). May be realized by software.

  In the latter case, the ECU 600 includes a CPU that executes instructions of a program that is software for realizing each function, a ROM (Read Only Memory) or a storage device in which the program and various data are recorded so as to be readable by a computer (or CPU). (These are referred to as “recording media”), and a RAM (Random Access Memory) for expanding the above program is provided. Then, the object of the present invention is achieved when the computer (or CPU) reads the program from the recording medium and executes the program. As the recording medium, a “temporary tangible medium”, for example, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, the program may be supplied to the computer via an arbitrary transmission medium (a communication network, a broadcast wave, or the like) capable of transmitting the program. Note that the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above-described program is embodied by electronic transmission.

  The present invention is not limited to the above embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

200 Body 600 ECU (control device)
610 Steering control unit 611 Base control amount calculating unit 612 Axial force correction current calculating unit 613 Control amount correcting unit 620 Rack axial force estimating unit 621 Roll rate related suspension damping force estimating unit 622 Roll angle related rack axial force estimating unit (second Rack axial force estimator)
623 Roll-related rack axial force estimator (adder, third rack axial force estimator)
624 Trail map application unit (vehicle state coefficient multiplication unit)
625 Multiplication unit (vehicle state coefficient multiplication unit)
626 Second constant gain application unit (vehicle state coefficient multiplication unit)
627 First constant gain application section (vehicle state coefficient multiplication section)
628 Roll rate related rack axial force estimating unit (first rack axial force estimating unit)
900 vehicle

Claims (5)

  A rack axial force estimating device for calculating an estimated value of a suspension damping force with reference to a roll rate of a vehicle body and estimating a rack axial force from the estimated value of the suspension damping force.   The rack axial force estimating device according to claim 1, wherein the rack axial force is estimated with further reference to a damping coefficient related value.   The rack axial force estimating device according to claim 2, wherein the rack axial force is estimated with further reference to the roll angle. A first rack axial force estimating unit that estimates a first rack axial force based on the roll rate and the damping coefficient related value;
A second rack axial force estimator for estimating a second rack axial force from the roll angle;
A third rack axial force estimating unit that estimates a third rack axial force by using the first rack axial force and the second rack axial force. 3. The rack axial force estimating device according to 3.   The rack axial force estimating device according to any one of claims 2 to 4, wherein the damping coefficient related value is a control amount for controlling a damping force of a suspension.

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