JP4744327B2 - Vehicle attitude control device - Google Patents

Description

  The present invention relates to a vehicle attitude control device that controls the running attitude of a vehicle, and relates to a technique for smoothly changing the attitude of a vehicle body during slalom running or when changing lanes.

  In recent years, active suspension systems based on skyhook theory have been developed as suspensions for automobiles. In the active suspension system, the distance between the vehicle body and the road surface (hereinafter referred to as ground clearance) on each wheel is controlled in real time using an actuator in accordance with the road surface condition and the vehicle motion state, etc. A good ride is obtained. For example, when the vehicle turns, the vehicle body rolls to the left and right due to the inertial force (lateral acceleration) that accompanies the lateral movement, but in an automobile equipped with an active suspension system (hereinafter referred to as an active suspension car), Drive the actuator on the outside of the turn to the extension side (the side where the wheel descends relative to the vehicle body), while driving the actuator on the inside of the turn to the contraction side (the side where the wheel rises relative to the vehicle body) Thus, the roll is suppressed (see Patent Document 1).

Some active suspension vehicles perform active control only on the rear wheel side to reduce the uncomfortable feeling during steering, and perform passive control (semi-active control) to increase or decrease the damping force on the front wheel side. In this case, it is inevitable that the vehicle body rolls outside the corner during cornering. Further, in recent active suspension vehicles, there are many settings in which a small amount of the vehicle body is rolled to the outside of the turn during turning, in order to alleviate the uncomfortable feeling experienced by the driver and to reduce the size and output of the actuator.
Japanese Patent Laid-Open No. 10-258628

  In the above-described active suspension vehicle, the posture change of the vehicle body may not be performed smoothly due to the fact that the vehicle body is set to roll outward when turning. During slalom travel or lane change, the turning direction continuously changes between right turn and left turn, and the roll direction is also reversed between right and left. For example, when turning right, the actuator on the left side (outside of the turn) is driven to the extension side, while the actuator on the right side (inside the turn) is driven to the contraction side, and from the moment when the right turn to the left turn is made. The left side (inside of turning) actuator is driven to the contraction side, while the right side (outside of turning) actuator is driven to the extension side. However, if the driving force of the actuator is set so that the vehicle body rolls outside the turn, there will be a slight time lag from when the turn direction changes until the roll direction is reversed, and the passenger feels uncomfortable. It will be.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a vehicle attitude control device that can smoothly change the attitude of a vehicle body during slalom traveling or lane change.

In order to solve the above-described problem, a vehicle attitude control device according to the invention of claim 1 is installed for each of the left and right suspensions, and an actuator for urging a wheel suspended on the suspension upward or downward; A vehicle attitude control device comprising roll suppression control means for driving and controlling the actuator with a predetermined control amount in order to suppress the roll of the vehicle body in the vehicle, further comprising a lateral acceleration detection means for detecting the lateral acceleration of the vehicle body The roll suppression control means for the actuator on the side where the wheel rises relative to the vehicle body when the absolute value of the time differential value of the lateral acceleration detection value output from the lateral acceleration detection means increases. At least a decrease in the control amount and an increase in the control amount for the actuator on the side where the wheel descends relative to the vehicle One and performing.

  According to a second aspect of the present invention, there is provided the vehicle attitude control device according to the first or second aspect of the invention, wherein the roll suppression control means is responsive to a time differential value of the lateral acceleration detection value. The control amount is increased or decreased by multiplying the control amount by the ratio.

  According to the vehicle attitude control device of the present invention, for example, when the time differential value of the lateral acceleration detection value increases when the automobile performs slalom traveling from a right turn to a left turn, the control force of the actuator on the extension side is increased. By increasing and reducing the control force of the actuator on the contraction side, the roll direction is quickly reversed, making it difficult for the occupant to feel uncomfortable.

  Hereinafter, embodiments in which the present invention is applied to a four-wheeled vehicle will be described in detail with reference to the drawings.

<< Configuration of Embodiment >>
1 is a schematic configuration diagram of a four-wheeled vehicle according to the embodiment, FIG. 2 is a block diagram illustrating a schematic configuration of an actuator control device according to the embodiment, and FIG. 3 is a main part of an active control unit according to the embodiment. It is a block diagram.

<Schematic configuration of automobile>
First, a schematic configuration of an automobile according to an embodiment will be described with reference to FIG. In the description, for the four wheels and members arranged for them, that is, tires, suspensions, and the like, suffixes indicating front, rear, left, and right are attached to the reference numerals, for example, wheel 3fl (front left), wheel 3fr (front right), wheel 3rl (rear left), wheel 3rr (rear right) and collectively referred to as wheel 3, for example.

  As shown in FIG. 1, an automobile (vehicle) V includes four wheels 3 on which tires 2 are mounted. Each wheel 3 is suspended from a vehicle body 1 by a suspension 4 including a suspension arm, a spring, a damper, and the like. Has been. Electric passive control actuators 5 are installed on the left and right front wheels, and the damping forces Dfr and Drl of the damper are variably controlled by these passive control actuators 5. Electric active control actuators 6 are installed on the left and right rear wheels, and vertical urging forces (hereinafter referred to as control forces Frl and Frr) are applied from the active control actuators 6 to the suspension 4 (that is, the wheels 3). ) Is given.

  The automobile V includes an ECU (Electronic Control Unit) 7 that is a control body of the suspension system and an EPS (Electric Power Steering) 8. In addition, the vehicle V is provided with a vehicle speed sensor 9 for detecting the vehicle speed, a lateral G sensor (lateral acceleration detection means) 10 for detecting lateral acceleration, a yaw rate sensor 11 for detecting yaw rate, and the like. A stroke sensor 12 for detecting the vertical acceleration and a vertical G sensor 13 for detecting vertical acceleration in the vicinity of the wheel house are provided for each wheel 3.

  The ECU 7 includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like. Both the actuators 5 and 6 are connected via a communication line (CAN (Controller Area Network) in this embodiment). And each sensor 9-13.

  The EPS 8 includes, as main components, a steering gear 21 including a rack and a pinion (not shown), a steering shaft 23 with a steering wheel 22 attached to the rear end, and an EPS motor 24 that applies a steering assist force to the steering shaft 23. A steering angle sensor (steering speed detection means) 25 for detecting the steering angle of the steering wheel 22 is attached to the steering shaft 23, and a detection signal of the steering angle sensor 25 is also output to the ECU 7.

<Schematic configuration of actuator control device>
As shown in FIG. 2, the ECU 7 includes an actuator control device (roll suppression control means) 30 that controls the passive control actuator 5 and the active control actuator 6. The actuator control device 30 includes an input interface 31 to which the various sensors 9 to 13 and 25 described above are connected, a passive control unit 32 that sets a damping force on the front wheel side based on a detection signal input from the input interface 31, An active control unit 33 that sets the control force on the rear wheel side based on the detection signal input from the input interface 31 and a drive signal output unit that outputs a drive signal to the passive control actuator 5 according to the setting result of the passive control unit 32 34 and a drive signal output unit 35 that outputs a drive signal (control amount) to the active control actuator 6 in accordance with the setting result of the active control unit 33.

  As shown in FIG. 3, the active control unit 33 sets the control forces Frl and Frr to be generated by the left and right active control actuators 6rl and 6rr based on detection signals of various sensors including the lateral G sensor 10. A force setting unit 41, a differentiator 42 for differentiating the lateral acceleration GL detected by the lateral G sensor 10 to calculate a lateral G differential value ΔGL, and determining whether the lateral G differential value ΔGL is outside the dead zone. A dead zone determination unit 43, an absolute value generation unit 44 that generates an absolute value | ΔGL | of the lateral G differential value ΔGL, an expansion side ratio map 45 for searching for the expansion side ratio Rr, and a contraction side ratio Rb. A contraction-side ratio map 46 for searching, a positive / negative determination unit 47 that determines whether the lateral G differential value ΔGL is positive or negative, and an expansion-side ratio Rr and a contraction-side ratio R based on the determination results of the positive / negative determination unit 47. The output (control force Frl, Frr) of the control force setting unit 41 is multiplied by a pair of switchers 48, 49 for switching the output destination of b, and the expansion side ratio Rr and the contraction side ratio Rb via the switches 48, 49. A pair of multipliers 50 and 51 are provided.

<< Operation of Embodiment >>
4 is a flowchart showing a procedure of transient ratio setting control according to the embodiment, FIG. 5 is an expansion-side ratio map according to the embodiment, FIG. 6 is a contraction-side ratio map according to the embodiment, and FIG. FIG. 8 is a flowchart showing a procedure of driving posture control according to the embodiment, and FIG. 8 is a graph showing a relationship between lateral acceleration, lateral G differential value, ratio, and control force according to the embodiment.

<Transient ratio setting control>
When the vehicle V starts driving, the ECU 7 executes, at a predetermined processing interval (for example, 10 ms), the transition ratio setting control whose procedure is shown in the flowchart of FIG.

  When the transient ratio setting control is started, the ECU 7 differentiates the lateral acceleration (lateral acceleration detection value) GL input from the lateral G sensor 10 with the differentiator 42 in step S1 of FIG. That is, the time differential value of the lateral acceleration GL) is obtained. Next, the ECU 7 determines whether or not the lateral G differential value ΔGL is outside the dead zone in step S2, and if this determination is No, the lateral G differential value ΔG is set to 0 in step S3 and step S4. If the determination in step S2 is Yes, the process proceeds directly to step S4. The dead zone is set to a value in a relatively small range including positive and negative values so that control hunting does not occur even when the driver turns the steering wheel a small amount when turning or changing lanes. ing.

  Next, after generating an absolute value | ΔGL | from the lateral G differential value ΔGL in step S4, the ECU 7 retrieves an expansion side ratio Rr corresponding to the absolute value | ΔGL | from the expansion side ratio map 45 in step S5. In step S6, the contraction ratio Rb corresponding to the absolute value | ΔGL | is searched from the contraction ratio map 46. As shown in FIG. 5, in the stretch side ratio map 45, the stretch side ratio Rr has an absolute value | ΔGL | that increases linearly from 1.0 within a predetermined range, but the absolute value | ΔGL | Even if it exceeds, it is fixed at the upper limit value (1.1 in this embodiment). Further, as shown in FIG. 6, in the contraction ratio ratio map 46, the contraction ratio Rb decreases linearly from 1.0 within the predetermined range within the absolute value | ΔGL |, but the absolute value | ΔGL | Even if the range is exceeded, it is fixed at the lower limit (0.9 in this embodiment).

  Next, the ECU 7 determines whether or not the lateral G differential value ΔGL is a positive value in step S7, and if this determination is Yes, in step S8, the expansion ratio Rr is changed to the left rear wheel side ratio Rrl. And the contraction side ratio Rb is set to the right rear wheel side ratio Rrr and the process returns to the start. If the determination in step S7 is No, the ECU 7 returns to the start in step S9 with the contraction side ratio Rb as the left rear wheel side ratio Rrl and the expansion side ratio Rr as the right rear wheel side ratio Rrr.

<Driving attitude control>
When the vehicle V starts driving, the ECU 7 executes driving posture control whose procedure is shown in the flowchart of FIG. 6 in parallel with the above-described transition ratio setting control.

  When the driving posture control is started, the ECU 7 reads the detection signals input from the various sensors 9 to 13 and 25 in step S21 in FIG. 7, and then in step S22 the passive control unit 32 controls the left and right front wheels 3fr and 3rl side. The damping forces Dfr and Drl are set, and the control forces Frl and Frr on the left and right rear wheels 3fl and 3rr are set by the active control unit 33 in step S23.

Next, in step S24, the ECU 7 updates the control forces Frl and Frr on the left and right rear wheels 3fr and 3rl using the left and right rear wheel ratios Rrl and Rrr obtained by the transient ratio setting control as shown in the following equation. And
Frl = Rrl · Frl
Frr = Rrr · Frr
In step S25, the damping forces Dfr and Drl and the control forces Frl and Frr are output to the passive control actuator 5 and the active control actuator 6, respectively.

Hereinafter, the relationship between the lateral acceleration GL, the lateral G differential value ΔGL, the ratio Rrl, and the control force Frl during slalom traveling will be described using the left rear wheel 3fl as an example.
As shown in FIG. 8, when the vehicle V runs slalom and the lateral acceleration GL (shown by a solid line ) applied to the vehicle body 1 smoothly changes from the negative direction to the positive direction, the lateral acceleration GL is reduced. The lateral G differential value ΔGL (indicated by a broken line ) increases or decreases in a negative region (indicated by cross hatching in FIG. 8), and when the lateral acceleration GL increases, the lateral G differential value ΔGL increases in a positive region (in FIG. 8). Increase or decrease with hatching).

  Then, the ratio Rrl on the left rear wheel 3fl side changes in the range of 0.9 to 1.1 according to the increase / decrease of the lateral G differential value ΔGL, except when the lateral G differential value ΔGL is in the dead zone. As a result, the control force Frl (shown by a solid line) output to the active control actuator 6 is slightly smaller on the contraction side than the value set by the control force setting unit 41 (shown by a broken line), and the extension side Then, it becomes a little big value. In the present embodiment, the active control actuators 6rl and 6rr are driven within the range of the maximum control force Fmax.

  In the present embodiment, by adopting such a configuration, the time delay of the reversal of the roll direction with respect to the change in the turning direction during slalom traveling, lane change, etc. is reduced, and the passenger's uncomfortable feeling is effectively alleviated. It became so.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, in the above embodiment, the present invention is applied to a four-wheeled vehicle having an active control actuator on the rear wheel side, but the present invention may be applied to a vehicle having an active control actuator on the front wheel side. However, it may be applied to a six-wheeled vehicle or the like. In the above embodiment, the control amount of the extension side actuator and the control amount of the contraction side actuator are both increased or decreased. However, the control amount of the extension side actuator and the control amount of the contraction side actuator are Only one of them may be increased or decreased. In the above embodiment, the ratio of the control amount is changed using the expansion side ratio map or the contraction side ratio map. However, a preset value may be added to or subtracted from the control amount. In addition, the specific configuration of the vehicle, the specific control procedure, and the like can be changed as appropriate without departing from the scope of the present invention.

1 is a schematic configuration diagram of a four-wheeled vehicle according to an embodiment. It is a block diagram which shows schematic structure of the actuator control apparatus which concerns on embodiment. It is a principal part block diagram of the active control part which concerns on embodiment. It is a flowchart which shows the procedure of the ratio setting control at the time of the transition which concerns on embodiment. It is an elongation side ratio map concerning an embodiment. It is a contraction side ratio map which concerns on embodiment. It is a flowchart which shows the procedure of the driving posture control which concerns on embodiment. It is a graph which shows the relationship of the lateral acceleration which concerns on embodiment, a lateral G differential value, a ratio, and control force.

Explanation of symbols

1 Car body 3 Wheel 4 Suspension 6 Active control actuator (actuator)
7 ECU
10 Lateral G sensor (lateral acceleration detection means)
30 Actuator control device (roll suppression control means)
V Automobile (vehicle)

Claims (2)

An actuator that is installed on each of the left and right suspensions and biases the wheel suspended on the suspension upward or downward;
A vehicle attitude control device comprising roll suppression control means for driving and controlling the actuator with a predetermined control amount in order to suppress the roll of the vehicle body during traveling,
A lateral acceleration detecting means for detecting a lateral acceleration of the vehicle body;
When the absolute value of the time differential value of the lateral acceleration detection value output from the lateral acceleration detection means is increased , the roll suppression control means is a control amount for the actuator on the side where the wheel rises relative to the vehicle body. The vehicle attitude control device is characterized in that at least one of the following is decreased and the control amount for the actuator on the side where the wheel descends relative to the vehicle body is increased .   The said roll suppression control means performs the increase or decrease of the said control amount by multiplying the said control amount by the ratio according to the time differential value of the said lateral acceleration detection value, The said control amount is characterized by the above-mentioned. Vehicle attitude control device.

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