JP6775069B2 - Rack axial force estimation device - Google Patents

Description

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

A steering device that applies an assist torque or a reaction force 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 (Patent Document 1) is known.

Japanese Unexamined Patent Publication No. 2010-100079 (published on May 6, 2010)

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

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

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

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

It is a figure which shows the schematic structure of the vehicle which concerns on Embodiment 1 of this invention. It is a block diagram which shows the schematic structure of the ECU which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structural example of the steering control part which concerns on Embodiment 1 of this invention. It is a figure which shows the mechanism about the change of the vehicle motion at the time of a roll motion, (a) shows the vehicle state at the time of straight running, (b) shows the vehicle state at the time of a turning roll, (c) is a roll angle. The relationship between and suspension stroke is shown. It is a figure which shows the mechanism about the change of the force when a roll motion occurs, (a) shows the relationship between a cornering force and a tire lateral force, and (b) shows the relationship of a rack axial force. It is a block diagram which shows the structural example of the suspension control part which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structural example of the steering control part which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structural example of the steering control part which concerns on Embodiment 3 of this invention.

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

(Structure of vehicle 900)
FIG. 1 is a diagram showing a schematic configuration of a vehicle 900 according to the present embodiment. As shown in FIG. 1, the vehicle 900 includes a suspension device (suspension) 100, a vehicle body 200, wheels 300, tires 310, steering member 410, steering shaft 420, torque sensor 430, steering angle sensor 440, torque application unit 460, and rack. It includes a pinion mechanism 470, a rack shaft 480, an engine 500, an ECU (Electronic Control Unit) (control device) 600, a power generation device 700, and a battery 800.

The wheel 300 on which the tire 310 is mounted is suspended from 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 four 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 the tire 310A and the wheel 300A, the tire 310B and the wheel 300B, the tire 310C and the wheel 300C, and the tire 310D and the wheel, respectively. Also called 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 represented by adding the symbols "A", "B", "C", and "D", respectively. There is.

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

A power generation device 700 is attached to the engine 500, and the electric 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 be able 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 the rotation of the steering shaft 420 around the axis into a displacement of the rack shaft 480 along the axial direction. When the rack shaft 480 is displaced in the axial direction, the wheels 300A and the wheels 300B are steered via the tie rod and the knuckle arm.

The torque sensor 430 detects the steering torque applied to the steering shaft 420, in other words, the steering torque applied to the steering member 410, and provides the ECU 600 with a torque sensor signal indicating the detection result. More specifically, the torque sensor 430 detects the twist of the torsion bar built in the 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, or 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.

The torque application unit 460 applies an assist torque or a reaction force torque according to the steering control amount supplied from the ECU 600 to the steering shaft 420. The torque application unit 460 includes a motor that generates an assist torque or a reaction force 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.

Specific examples of the "control amount" in the present specification include a current value, a duty ratio, an attenuation rate, and an attenuation ratio.

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

In the above description, "connecting so that torque can be transmitted" means that the other member is connected so as to rotate with the rotation of one member, for example, one member and the other member. Is integrally molded, the other 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. At least include cases where it is connected to.

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

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

Further, the ECU 600 controls the opening and closing of the solenoid valve by supplying a suspension control amount to the solenoid valve included 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 arranged.

Further, the vehicle 900 is provided for each wheel 300, has a wheel speed sensor 320 that detects the wheel speed of each wheel 300, a lateral G sensor 330 that detects the lateral acceleration of the vehicle 900, and detects the acceleration in the front-rear direction of the vehicle 900. The front and rear G sensor 340, the yaw rate sensor 350 for detecting the yaw rate of the vehicle 900, the engine torque sensor 510 for detecting the torque generated by the engine 500, the engine rotation speed sensor 520 for detecting the rotation speed of the engine 500, and the braking device. A brake pressure sensor 530 that detects the pressure applied to the brake liquid is provided. The detection results by these various sensors are supplied to the ECU 600.

The vehicle 900 may further include a roll rate sensor that detects the roll rate of the vehicle body 200 and a stroke sensor that detects the 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), which suppresses wheel slippage during acceleration, and the like. It is equipped with a VSA (Vehicle Stability Assist) controllable braking device, which is a vehicle behavior stabilization control system equipped with an automatic braking function for yaw moment control during turning and a brake assist function.

Here, ABS, TCS, and VSA compare the wheel speed determined according to the estimated vehicle body speed with the wheel speed detected by the wheel speed sensor 320, and the values of these two wheel speeds are predetermined values. If the above differences are made, it is determined that the vehicle is in a slipped state. Through such processing, ABS, TCS, and VSA aim to stabilize the behavior of the vehicle 900 by performing optimum brake control and traction control according to the traveling state of the vehicle 900.

Further, the supply of the detection results by the various sensors described above to the ECU 600 and the transmission of the control signal from the ECU 600 to each part are performed via the CAN (Controller Area Network) 370.

(ECU 600)
Hereinafter, the ECU 600 will be specifically described by changing the reference drawing. 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 supplied to the torque application unit 460.

In the present specification, the expression "refer to" may include meanings such as "using", "considering", and "depending on".

The suspension control unit 650 refers to the detection results of various sensors included in the CAN 370, and determines the magnitude of the suspension control amount 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.

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 may represent the roll rate as a deviation from the reference value. ..

Further, 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 control amount is not supplied.

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

(Steering control unit)
Subsequently, the steering control unit 610 will be described more specifically with reference to FIG. FIG. 3 is a block diagram showing 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 controls the magnitude of the assist torque or the reaction force torque with reference to the steering torque supplied from the torque sensor 430 and the vehicle speed determined according to the wheel speed detected by the wheel speed sensor 320. Calculate the control amount for. 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 estimation unit)
The rack axial force estimation unit 620 estimates the rack axial force with reference to the roll rate supplied from the roll rate sensor. As shown in FIG. 3, the rack axial force estimation unit 620 includes a roll rate-related suspension damping force estimation unit 621 and a first constant gain application unit 627. The roll rate-related suspension damping force estimation unit 621 and the first constant gain application unit 627 are combined with the roll rate-related rack axial force estimation unit 628 (first rack axial force estimation unit in the claims). , Sometimes called.

The roll rate-related suspension damping force estimation 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 the value of the suspension control current as the suspension control amount. It can be said that Df _{1 to} Df ₃ are values related to the attenuation coefficient.

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

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

The first constant gain application unit 627 applies the gain corresponding to the vehicle 900 to the estimated value of the damping force of the suspension according to the roll rate. More specifically, the estimated value of the suspension supplied from the roll rate-related suspension damping force estimation unit 621 is multiplied by a correction coefficient according 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 estimation unit 620 may further refer to the suspension control current to estimate the rack axial force according to the roll rate. In this case, the roll rate map referred to by the roll rate-related suspension damping force estimation 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. By referring to this roll rate map, the roll rate-related suspension damping force estimation unit 621 responds to the roll rate based on the roll rate supplied from the roll rate sensor and the suspension control current supplied from the suspension control unit 650. The estimated value of the damping force of the suspension is calculated and output to the first constant gain application unit 627. The first constant gain application unit 627 calculates and outputs the estimated rack axial force from the estimated value of the damping force of the suspension according to the roll rate.

Here, the roll rate-related suspension damping force estimation unit 621 calculates and outputs a larger suspension damping force estimation value as the suspension control current increases.

That is, it can be said that the rack axial force estimation unit 620 calculates and outputs the estimated rack axial force larger 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.

In this way, 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, which makes the driver feel uncomfortable. A small assist torque or reaction force torque can be applied to the steering member 410.

Further, since 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, the vehicle body 200 can be estimated. The roll change in the transient state can be identified. In this way, the control amount correction unit 613 corrects the control amount calculated by the base control amount calculation unit 611 according to the roll change in the transient state of the vehicle body 200, so that the assist torque or anti-torque is less uncomfortable for the driver. Force torque can be applied to the steering member 410.

(Calculation method of estimated rack axial force)
Subsequently, the calculation method of the estimated rack axial force will be described more specifically with reference to FIGS. 4 and 5. 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.

FIG. 4 is a diagram showing a mechanism related to a change in vehicle motion when a roll motion occurs, (a) shows a vehicle state when going straight, (b) shows a vehicle state when turning and rolling, and (c) is a diagram. The relationship between the roll angle and the suspension stroke is shown.

As shown in FIG. 4, in the vehicle state during a 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, lateral G force, centrifugal force, roll moment, and load transfer are present. Occur. 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 cornering on the inner ring side 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 _ct [kgf], the lateral G is Gy [G'], and the roll moment is M _roll [kgf ・ m]. , The load transfer is expressed as ΔW [kgf], the roll angle is expressed as θ _roll [deg], the inner ring side stroke amount is expressed as D _in [m], and the outer ring side stroke amount is expressed as D _out [m].

As shown in FIG. 4B, the centrifugal force of the vehicle 900 during turning and the tire cornering force are in equilibrium, and are expressed by the following equation (1).

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

The following equation (4) can be obtained by _{combining the} above equations (2) and (3) with respect to _Mroll .

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

W _car indicates the weight of the vehicle 900, 1/2 × a × W _car and 1/2 × a × W _car indicate the load in the 1G state, and −a × ΔW, −b × ΔW, a. × ΔW and b × ΔW indicate the load transfer amount.

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

The relational expression between the load transfer and the stroke amount is expressed by the following equation (6). The following equation (6) expresses the relational expression between the load transfer on the front wheel side and the stroke amount.

In addition, DF _fr represents the front wheel damping coefficient [kgfs / m], and K _fr represents the spring coefficient [kgf / m] of the front wheel.

When the extension stroke amount and the contraction stroke amount of the suspension 100 on the inner and outer rings are equivalent on the left and right, it is expressed by the following equation (7).

Note that D _eq represents the equivalent stroke amount [m].

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

Further, by applying the above formula (7) to the above formula (6), the following formula (9) can be obtained.

In addition, it should be noted

Indicates the 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),

,

Replace with. Further, in the above formula (9),

Replace with, rearrange the formula, and obtain the following formula (10).

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

Next, with reference to FIG. 5, the mechanism from the viewpoint of the change in force when the roll motion occurs will be described. 5A and 5B are diagrams showing a mechanism related to a change in force when a roll motion occurs, in which FIG. 5A shows the relationship between the cornering force and the tire lateral force, and FIG. 5B shows the relationship between the rack axial force. Here, in FIG. 5, the cornering force is CF [kgf], the tire lateral force is TF _y [kgf], the skid angle is α [°], the tire rolling resistance is TF _x [kgf], and the 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 expressed 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 expressed by the following equation (12).

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

The rack axial force is expressed by the following equation (14).

Substitute the above equation (13) into the above equation (14). Here, the skid angle is small,

If it is,

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

The following equation (16) can be obtained by arranging the relational expressions of the above equations (11) and the above equations (15) simultaneously with respect to CF.

By using the above equation (16), the rack axial force estimation unit 620 can input coefficients according to the roll rate, roll angle, and vehicle 900, and output the estimated rack axial force. The estimated rack axial force related to the roll rate (roll rate-related estimated rack axial force, first rack axial force within the claims) estimated by the roll rate-related rack axial force estimation unit 628 is the above equation (16). In,

Corresponds to. Further, the estimated rack axial force related to the roll angle (roll angle-related estimated rack axis) estimated by the roll angle-related rack axial force estimation unit 622 (second rack axial force estimation unit in the claims) described later in the second embodiment. The force, the first rack axial force in the claims) is the force in the above equation (16).

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

Corresponds to. The correction coefficient determined by the second constant gain application unit 626, which will be described later, is in the above equation (16).

Corresponds to.

(Suspension control unit)
Subsequently, the suspension control unit will be described with reference to FIG. FIG. 6 is a block diagram showing 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 / riding 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 the acquisition source).

・ Wheel speed of 4 wheels (wheel speed sensor 320A to D)
・ Yaw rate (yaw rate sensor 350)
・ Front and rear G (front and rear 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)
・ Rudder angle (rudder angle sensor 440)
The vehicle state estimation unit 670 estimates the state of the vehicle 900 with reference to various signals acquired by the CAN input unit 660. As an estimation result, the vehicle state estimation unit 670 outputs the spring speed of the four wheels, the stroke speed of the four wheels, the pitch rate, the roll rate, the roll rate during steering, and the pitch rate during acceleration / deceleration.

As shown in FIG. 6, 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. It has.

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

The acceleration / deceleration / steering pitch / roll rate calculation unit 673 calculates the steering roll rate and the acceleration / deceleration pitch rate with reference to the front-rear G and the lateral G. The calculation result is supplied to the state estimation single-wheel model application unit 674.

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

In this way, the acceleration / deceleration / steering pitch / roll rate calculation unit 673 supplies the steering roll rate calculated with reference to the front / rear G and the lateral G as a roll rate value to the steering control unit 610, and steers. Since the control unit 610 corrects the control amount for controlling the magnitude of the assist torque or the reaction force torque with reference to the roll rate value, the steering control unit 610 more preferably controls the assist torque or the reaction force torque. The size can be corrected.

Further, as described above, if the acceleration / deceleration / steering pitch / roll rate calculation unit 673 further refers to the suspension control amount output by the control amount selection unit 690, the steering control unit 610 is more preferable. The magnitude of the assist torque or the reaction force torque can be corrected.

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

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

The skyhook control unit 681 performs ride comfort control (vibration control control) that suppresses the shaking of the vehicle when overcoming the unevenness of the road surface and enhances the ride comfort. As an example, the skyhook control unit 681 determines the skyhook target control amount with reference to the spring speed of the four wheels, the stroke speed of the four wheels, the pitch rate, and the roll rate, and determines the result as the control amount selection unit. Supply to 690.

As a more specific example, the skyhook control unit 681 sets the damping force base value by referring to the spring-damping force map based on the spring 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, the 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 at the time of 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 angle speed. The steering angle speed proportional target control amount, which is an amount, and the roll rate proportional target control amount, which is a target control amount according to the roll rate, are determined, and the results are supplied 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 the steering torque signal indicating the steering torque. Here, the steering control unit 610 may supply the steering torque signal to the suspension control unit 650, and the steering torque signal may be referred to by the steering control unit 610. The steering torque signal may be phase-compensated. As a result, it can be expected that a more comfortable ride will be realized.

In this way, the roll attitude control unit 682 performs roll attitude control with reference to the roll rate at the time of steering calculated by the pitch / roll rate calculation unit 673 at the time of acceleration / deceleration / steering, and thus performs suitable attitude control. Can be done. Further, the roll rate at the time of steering calculated by the pitch / roll rate calculation unit 673 at the time of acceleration / deceleration / steering is not only the roll attitude control by the roll attitude 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 force torque, it is possible to provide suitable attitude control and a comfortable steering feeling while suppressing an increase in the 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 unit 684 controls the unsprung vibration of the vehicle 900 with reference to the wheel speeds of the four wheels, and determines the unsprung vibration control control target control amount. The determination result is supplied to the control amount selection unit 690.

The control amount selection unit 690 sets the skyhook target control amount, the steering angle proportional target control amount, the steering angle speed proportional target control amount, the roll rate proportional target control amount, the pitch target control amount, and the spring-down vibration suppression control target control amount. Among them, 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 example]
The rack axial force estimation unit 620 according to the present embodiment has a roll rate output by the vehicle state estimation unit 670 of the suspension control unit 650 instead of the roll rate supplied from the roll rate sensor, in other words, the damping force of the suspension. The roll rate as an estimated value referred to for calculating the control amount for controlling the roll rate may be used as an input to the roll rate-related rack axial force estimation unit 628.

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

As described above, the rack axial force estimation unit 620 according to the present embodiment has a configuration in which the rack axial force is estimated by using the roll rate and the damping coefficient related value. Since the rack axial force estimation unit 620 according to the present embodiment estimates the rack axial force using the roll rate and the value related to the damping coefficient, the rack axial force can be preferably estimated.

[Embodiment 2]
Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG. 7.

FIG. 7 is a block diagram showing a configuration example of the steering control unit according to the present embodiment. The steering control unit according to the present embodiment has a configuration in which the rack axial force estimation unit 620 further includes a roll angle-related rack axial force estimation unit 622 and an addition unit 623 in the steering control unit 610 according to the first embodiment. In the following description, the same members as those already described will be designated by the same reference numerals and the description thereof will be omitted.

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

The roll angle-related rack axial force estimation 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 addition unit 623. As a method of acquiring the roll angle, for example,
-Integrate the roll rate supplied from the roll rate sensor and acquire the integrated value as the roll angle.
-The roll rate output by the vehicle state estimation unit 670 is integrated, and the integrated value is acquired as the roll angle, and
-The vehicle 900 is configured to include a roll angle sensor, and the roll angle is acquired from the roll angle sensor. Further, as the roll angle-related rack axial force estimation unit 622, for example, a roll angle-related damping force estimation unit that estimates the damping force from the roll angle, and a gain corresponding to the vehicle 900 in the estimated roll angle-related damping force estimation value. A third constant gain application unit for multiplying by is included, but the roll angle-related rack axial force estimation unit 622 according to the present embodiment is not limited to this. As an example of the third constant gain application unit, an amplifier can be mentioned.

The addition unit 623 adds the roll rate-related estimated rack axial force supplied from the roll rate-related rack axial force estimation unit 628 and the roll angle-related estimated rack axial force supplied from the roll angle-related rack axial force estimation unit 622. Then, the roll-related estimated rack axial force is calculated. The addition unit 623 is configured to add the estimated roll rate-related estimated rack axial force, which is the estimated rack axial force, and the estimated roll angle-related estimated rack axial force to calculate the estimated rack axial force. Therefore, it can be paraphrased as a roll-related rack axial force estimation unit (third rack axial force estimation unit within the scope of claims).

As described above, the rack axial force estimation unit 620 according to the present embodiment further refers to the roll angle in addition to the roll rate and damping coefficient related values described above, and the rack axial force related to the roll (the first in the claims). The rack axial force of 3) 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 uses the control amount calculated by the base control amount calculation unit 611 as the roll-related estimated rack axial force (roll rate-related estimated rack axial force and roll) calculated by the rack axial force estimation unit 620. The estimated rack axial force obtained by adding the angle-related estimated rack axial force) is referred to and corrected.

In this way, the control amount correction unit 613 corrects the control amount calculated by the base control amount calculation unit 611 with reference to the roll-related estimated rack axial force calculated by the rack axial force estimation unit 620. It is possible to apply an assist torque or a reaction force torque to the steering member 410, which is less uncomfortable for the person.

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

FIG. 8 is a block diagram showing a configuration example of the 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 to prepare. Further, in the steering control unit 610 according to the second embodiment, the roll rate-related rack axial force estimation unit 628 to the first constant gain application unit 627 are removed, and the roll angle-related rack axial force estimation unit 622 has a third constant gain application unit. It is a configuration excluding (amplifier).
In the following description, the same members as those already described will be designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 8, the trail map application unit 624 determines the correction coefficient with reference to the trail map. 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 the prior art.

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

The second constant gain application unit 626 relates to the estimated damping force supplied from the multiplication unit 625 (estimated rack axial force obtained by multiplying the roll-related estimated rack axial force by the correction coefficient supplied from the trail map application unit 624). Then, the gain corresponding to the vehicle 900 is applied. More specifically, the vehicle 900 is subjected to the estimated damping force supplied from the multiplication unit 625 (the estimated damping force obtained by multiplying the roll-related estimated damping force by the correction coefficient supplied from the trail map application unit 624). Multiply the corresponding correction factors to calculate the estimated rack axial force. 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.

In the present embodiment, the first constant gain application unit 627 in the roll rate-related rack axial force estimation unit 628 and the third constant gain application unit in the roll angle-related rack axial force estimation unit 622 according to the second embodiment are second. It is replaced with the constant gain application unit 626.

Therefore, in the present embodiment, the roll rate-related suspension damping force estimation unit 621 in the roll rate-related rack axial force estimation unit 628 and the second constant gain application unit 626 are combined to form the roll rate-related rack axial force estimation unit 628. In the roll angle-related rack axial force estimation unit 622, the roll angle-related damping force estimation unit and the second constant gain application unit 626 are collectively regarded as the roll angle-related rack axial force estimation unit 622. be able to.

Therefore, it can be said that the present embodiment has a configuration in which the roll-related rack axial force is estimated from the roll rate-related rack axial force and the roll angle-related rack axial force.

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

As described above, the rack axial force estimation unit 620 according to the present embodiment refers to the correction coefficient according to the vehicle 900 in addition to the roll rate, the damping coefficient related value, and the roll angle described above, and obtains 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 uses the control amount calculated by the base control amount calculation unit 611 as the roll-related estimated rack axial force (roll rate-related estimated rack axial force and roll) calculated by the rack axial force estimation unit 620. The estimated rack axial force obtained by adding the angle-related estimated rack axial force) and the correction coefficient according to the vehicle 900 are referred to for correction.

In this way, the control amount correction unit 613 applies the control amount calculated by the base control amount calculation unit 611 to the roll-related estimated rack axial force (roll rate-related estimated rack axial force and roll) calculated by the rack axial force estimation unit 620. Assist torque or reaction torque that does not cause discomfort to the driver by correcting by referring 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 realization by software]
The control block (steering control unit 610, 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 a CPU (Central Processing Unit) is used. It may be realized by software.

In the latter case, the ECU 600 is a CPU that executes instructions of a program that is software that realizes each function, a ROM (Read Only Memory) or a storage device in which the program and various data are readablely recorded by a computer (or CPU). (These are referred to as "recording media"), RAM (Random Access Memory) for developing the above program, and the like are provided. Then, the object of the present invention is achieved by the computer (or CPU) reading the program from the recording medium and executing the program. As the recording medium, a "non-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 (communication network, broadcast wave, etc.) capable of transmitting the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

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

Claims (5)

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

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