Vehicle body position control device

Abstract

Vehicle body position control device for controlling the position of a vehicle body, the device comprising: a target pitch rate calculation unit (16, 17, 18; 50) configured to calculate a target pitch rate as a target value of a pitch rate of the vehicle body according to a roll rate of the vehicle body; and a pitch moment generation unit (19, 21, 22, 23, 24, 6, 9; 51, 52, 53-56, 61-54, 6, 9; 19, 21, 22, 72, 73, 74) configured to generate a pitch moment applied to the vehicle body so that the pitch rate of the vehicle body approaches the target pitch rate.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a vehicle body attitude control apparatus for use in preferably a vehicle, such as a four-wheeled vehicle.

[0002] In general, a vehicle body position control device is known which is designed to reduce a roll rate by calculating a lateral acceleration from a steering angle and a vehicle speed, by obtaining the lateral jerk by deriving the lateral acceleration, and by switching the damping forces of the respective suspensions of the front, rear, left, and right wheels according to the lateral jerk (see, for example, Japanese patent application publication no. 2007-290650).

[0003] Furthermore, a device is also known which is capable of achieving a target behavior of a vehicle body in order to stabilize the position of the vehicle body by obtaining a target roll angle from the lateral acceleration while the vehicle is moving, calculating a target pitch angle according to the target roll angle, and performing feedback control (FB control) by obtaining a difference between an actual roll angle and an actual pitch angle (see, for example, the Japanese patent application publication no. 2007-170590).

[0004] On the other hand, a driver's perception during a vehicle steering maneuver has been studied in various research projects to date, as indicated by Non-Patent Documents 1, 2, and 3, which are listed in the "List of Non-Patent Documents" below. Non-Patent Document 1 focuses on the relationship between roll and pitch angles while the vehicle is in motion and discusses how reducing the phase difference between roll and pitch angles can improve a driver's perception, such as ride comfort and steering stability. Non-Patent Document 2 discusses how a driver may experience a positive perception of roll behavior accompanied by a forward head-down pitching sensation when the driver turns the steering wheel.Non-patent document 3 discusses that a driver may feel good if the axis of rotation hardly wobbles, provided that the roll and pitch behavior of the vehicle are in harmony.

[0005] The contents of these non-patent documents 1 to 3 can generally be divided into two points, as indicated by points (1) and (2) below. (1) The phase difference between a roll angle and a pitch angle is small. → The phase difference between a roll rate and a pitch rate is small. → The roll rate and the pitch rate are proportionally related. → The rotation axis of a roll and pitch movement is stabilized, and in particular, non-patent documents 1 and 3 indicate that the rotation axes of roll and pitch hardly wobble. (2) Non-patent document 2 indicates that a swaying behavior is accompanied by a forward nodding. [LIST OF NON-PATENT DOCUMENTS][NON-PATENT DOCUMENT 1]

[0006] “Improvement of roll perception based on visual sensitivity”, written by Hideki Sakai and 5 others, published in the TOYOTA Technical Review Vol. 55 No. 1 (November 2006) pages 20 to 24. [NON-PATENT DOCUMENT 2]

[0007] “A Study of Vehicle Roll Behavior (Suspension Technology to Improve Roll Sensation)”, written by Kenji Kawagoe, published in the Journal of the Society of Japanese Automotive Engineers (Automotive Technology) Vol. 51 No. 11 (1997) Pages 20 to 24. [NON-PATENT DOCUMENT 3]

[0008] “Vehicle Position Measurement Method with GPS”, written by Hitoshi Fukuba and 2 others, published in the Technical Overview by Matsuda No. 20 (2002) pages 130 to 138.

[0009] However, the related technology discussed in the aforementioned Japanese patent application publication No. 2007-290650 discusses a logic that only aims to reduce roll rate and therefore may not be able to solve a bad feeling during transitional cornering if roll rate and pitch rate are not closely related or an unwanted pitch rate is generated.

[0010] Additionally, the two other related technologies also present a problem in that they are supposed to control a vehicle's position even during normal cornering, in order to generate a pitch angle corresponding to a roll angle while the vehicle is moving. However, controlling dampers with variable damping force could compromise ride comfort, while controlling the brakes cannot prevent excessive deceleration of the vehicle. SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to provide a vehicle body position control device that is capable of providing an improvement in cornering stability and driving comfort while the vehicle is in motion.

[0012] To achieve the above-mentioned and further objectives, the present invention is a vehicle body attitude control device for controlling the attitude of a vehicle body. The vehicle body attitude control device comprises a target pitch rate calculation unit configured to calculate a target pitch rate as a target value for the pitch rate of the vehicle body, such that the pitch rate is increased according to a degree of roll rate of the vehicle body, and a pitch moment generation unit configured to generate a pitch moment that is applied to the vehicle body so that the pitch rate of the vehicle body approaches the target pitch rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Fig. Figure 1 shows a perspective view of a four-wheeled automobile on which a vehicle body position control device according to a first embodiment or a second embodiment of the present invention is applied;

[0014] Fig. 2 is a control block diagram representing the vehicle body position control device according to the first embodiment;

[0015] Fig. Figure 3 represents a characteristic curve showing the relationship between a roll angle and a pitch angle of the vehicle in which the present invention is applied;

[0016] Fig. Figure 4 represents a characteristic curve that shows the relationship between a roll rate and a pitch rate of the vehicle in which the present invention is applied;

[0017] Fig. Figure 5 represents characteristic curves that show the relationship between a frequency and a gain in a transfer function for calculating a pitching moment from a target pitch rate;

[0018] Fig. Figure 6 represents characteristic curves that show the relationship between a frequency and a phase in the transfer function for calculating a pitching moment from a target pitch rate;

[0019] Fig. Figure 7 is a control block diagram representing the processing that uses a target damping force calculation unit, which is in Fig. 2 is shown, in order to calculate target damping forces of the respective wheels from a pitching moment;

[0020] Fig. Figure 8 is a top view that schematically illustrates how a vehicle travels while cornering;

[0021] Fig. Figure 9 represents characteristic curves that show the relationship between a steering angle, lateral acceleration, roll angle, pitch angle, roll rate and pitch rate while the vehicle is cornering;

[0022] Fig. Figure 10 represents a characteristic curve that shows the relationship between the roll angle and the pitch angle, which is in Fig. 9 is shown, indicates;

[0023] Fig. 11 represents a characteristic curve that illustrates the relationship between a roll angle and a pitch angle in a comparative example;

[0024] Fig. 12 is a control block diagram illustrating the vehicle body position control device according to the second embodiment; and

[0025] Fig. Figure 13 is a control block diagram representing a vehicle body position control device according to the third embodiment.

[0026] Fig. Figure 14 is a control block diagram representing a vehicle body position control device according to the fourth embodiment. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0027] In the following, a vehicle body position control device according to embodiments of the present invention is described in detail with reference to the accompanying drawings, based on an example in which this device is used, for example a four-wheeled vehicle.

[0028] Fig. 1 to Fig. Figure 10 represents a first embodiment of the present invention. In the drawings, reference numerals denote 1 A vehicle body, which represents the main structure of the vehicle. The vehicle body includes, for example, front left and right wheels. 2 (only one of them is shown) and rear left and right wheels 3(only one of them is shown), which are located on the underside of the vehicle body.

[0029] Reference sign 4 refers to front wheel side suspension devices that are located between the front left and right wheels 2 and the vehicle body 1 are arranged. The front-wheel suspension devices 4 each includes a left or right suspension spring 5 (hereinafter referred to as “feather”) 5 (designated as “), and a left or right adjustable damping force shock absorber 6 (hereinafter referred to as “variable damping force damper”) 6 (designated) between the left or right wheel 2 and the vehicle body 1 parallel to the left or right spring 5 is arranged. The variable damping force damper 6represents part of a pitching moment generation unit, which is a forming element of the present invention.

[0030] Reference sign 7 refers to rear-side suspension devices located between the left and right wheels 3 and the vehicle body 1 are arranged. The rear-side suspension devices 7 each includes a left or right suspension spring 8 (hereinafter referred to as “feather”) 8 (designated) and a left or right adjustable damping force shock absorber 9 (hereinafter referred to as “variable damping force damper”) 9 (designated) between the rear left or right wheel 3 and the vehicle body 1 parallel to the left or right spring 8 is arranged. The variable damping force damper 9 represents part of the pitching moment generation unit.

[0031] The variable damping force dampers 6 and 9 the respective suspension devices 4 and 7 Each is designed using a hydraulic shock absorber capable of adjusting its damping force. These are variable damping force shock absorbers. 6 and 9 Each is attached to an actuator (not shown), which is formed, for example, by a damping force adjustment valve and a coil, to continuously adjust its damping force characteristic from a hard characteristic curve (hardness) to a soft characteristic curve (softness). However, the actuator for adjusting the damping force does not necessarily have to be designed to continuously change the damping force characteristic curve, but can be designed to adjust the damping force characteristic curve in a stepped manner comprising two, three, or more steps. Furthermore, the variable damping force damper can 6 and 9be embodied by any damper capable of changing the damping force, such as a pneumatic damper or an electromagnetic damper.

[0032] Reference sign 10 refers to a roll rate sensor, which is, for example, a gyroscope, as a roll state determination unit (roll rate determination unit) that is attached to the vehicle body 1 is arranged, is formed. The roll rate sensor 10 It determines a lateral acceleration from side to side, which can be generated, for example, when the vehicle is driving in a curve according to a steering input, and sends the determined signal to a control unit. 13from which, which will be described later. The roll rate determination unit can be embodied by any sensor capable of determining a roll rate by, for example, integrating a difference between two vertical acceleration sensors arranged in a spaced-apart relationship in the transverse direction.

[0033] Reference sign 11 refers to a pitch rate sensor, which is, for example, a gyroscope, as a pitch state detection unit (pitch rate detection unit) that is attached to the vehicle body 1 is arranged, is formed. The pitch rate sensor 11 It detects a vibration in the longitudinal direction, which can be generated during, for example, acceleration or deceleration of the vehicle, and sends the detected signal to the control unit. 13 from which, which will be described later. A single three-dimensional gyroscope can function as both the roll sensor mentioned above. 10as well as this nautical rate sensor 11 Furthermore, the pitch rate determination unit can be embodied by any sensor capable of determining a pitch rate, for example, by integrating the difference between two vertical acceleration sensors arranged in a spaced-apart relationship along the longitudinal axis. Alternatively, a pitch rate (estimated value) can be obtained by estimating a braking force resulting from driver input or an automatic braking system input, and an acceleration value resulting from accelerator pedal input.

[0034] Reference sign 12 refers to a lateral acceleration sensor that is integrated into the vehicle structure 1 is arranged. The lateral acceleration sensor 12It determines the lateral acceleration that can be generated in the side direction of the vehicle, for example, while the vehicle is cornering, and sends the determined signal to the control unit. 13 from which will be described later.

[0035] Reference sign 13 A control unit is defined as a control unit formed by, for example, a microcomputer. As in Fig. Shown in section 2 is the input side of the control unit. 13 for example, the roll rate sensor 10 , the pitch rate sensor 11 and the lateral acceleration sensor 12 connected. The output side of the control unit 13 is with, for example, the actuators (not shown) of the variable damping force damper 6 and 9 connected. A signal 14 , which indicates a roll angle, which in Fig. As shown in 2, a lateral acceleration signal is generated from the lateral acceleration sensor. 12 is determined, calculated. Furthermore, a signal can 15 , which displays a relative speed, using a signal from a vehicle height sensor (not shown) designed to measure the height of the vehicle body 1 to determine, be determined, or can be obtained based on signals from a spring-loaded accelerometer and an unspring-loaded accelerometer (not shown).

[0036] As in Fig. The control unit shown in section 2 includes... 13 an enhancement 16 , an investigative unit 17 , a multiplication unit 18 , an FF control unit 19 , a difference calculation unit 20 , an FB calculation unit 21 , an average value calculation unit 22 , a target damping force calculation unit 23and a damper instruction value calculation unit 24 .

[0037] One in Fig. 3 characteristic curve shown 25 It represents an ideal relationship (characteristic curve) between a roll angle and a pitch angle as a proportional characteristic curve. A characteristic curve segment 25A corresponds to positive values ​​of a tilt angle and a characteristic curve segment 25B This corresponds to negative values ​​of a roll angle. A characteristic curve 26 , which in Fig. Figure 4 shows an ideal relationship (characteristic curve) between roll rate and pitch rate when the vehicle performs a lane change, as a proportional characteristic curve. The characteristic curve 26 includes characteristic curve segments 26A and 26B , which intersect at the zero position, and a characteristic curve segment 26C , which extends parallel to the vertical axis to the ends of the characteristic curve segments 26A and 26B to connect.

[0038] The relationship between the characteristic curve 25 , which in Fig. 3 is shown, and the characteristic curve 26 , which in Fig. Figure 4 shows a related characteristic curve encompassing corresponding events designated by the letters (a), (b), (c), (d), (e), (f), and (g). Assuming, for example, that the starting point is letter (a), representing the vehicle traveling straight ahead when a driver initiates a lane change by turning a steering wheel, the roll angle begins, as indicated by the arrow along letter (b), as shown in Figure 4. Fig. 3 shown, to increase. At this point, since the pitch angle also increases, both the roll rate and the pitch rate, which are shown in Fig. As shown in Figure 4, positive values ​​(+) are displayed. When the increasing rate of the roll angle reaches its peak, the roll rate and pitch rate reach their respective maximum values ​​at the position marked (b), as shown in Figure 4. Fig. 4 shown.

[0039] Subsequently, when the roll angle and pitch angle reach their respective maximum values ​​at the position marked with the letter (c), as in Fig. 3 shown, denoted, both the roll rate and the pitch rate approach zero, as indicated by the letter (c), as in Fig. As shown in Figure 4, the driver then begins to return the steering wheel to neutral, and subsequently the roll rate reaches its maximum value in the negative (minus) direction at the position marked (d), when the roll angle approaches zero. At the same time, the pitch rate, which indicates a rotation in the opposite direction, changes along the characteristic curve segment. 26C , which in Fig. 4 is shown. Furthermore, when the relationship between the roll angle and the pitch angle changes, as with the letters (d), (e), (f) and (g), as in Fig. As shown in section 3, the relationship between the roll rate and the pitch rate changes, as indicated by the letters (d), (e), (f) and (g), as in Fig. Figure 4 shows, denoted. Alternatively, instead of generating the perfectly proportional relationship as mentioned above, a non-linear relationship between the roll angle and the pitch angle and between the roll rate and the pitch rate can be generated under the condition that the increases and decreases of the roll angle and the pitch angle are related as shown in Fig. 3 shown, and the increases and decreases in roll rate and pitch rate are related as shown in Fig. 4 shown.

[0040] The reinforcement 16 of the control unit 13 multiplies a roll rate signal that comes from the roll rate sensor 10 was determined with a gain that was predetermined for each vehicle, that is, a gain based on the characteristic curve 26 , which in Fig. 4 is shown, and calculates a pitch rate that corresponds to the roll rate at that time from the characteristic curve. 26as a target nick rate.

[0041] The investigation unit 17 determines the sign of the roll rate signal 14 exhibits, that is, whether the roll angle signal 14 a positive value or a negative value, based on a lateral acceleration signal from the lateral acceleration sensor 12 was determined. The multiplication unit 18 calculates a corrected target nick rate value by multiplying the signal (target nick rate) by the gain 16 with the determined sign, so that the vehicle is set into a nosedive state (a pitching motion where the front of the vehicle is lowered further than the rear). The amplification 16 , the investigation unit 17 and the multiplication unit 18form a target pitch rate calculation unit, which is an integral part of the present invention.

[0042] The FF control unit 19 The following equations (1) to (3) are calculated at the input of the corrected target pitch rate value, resulting in a target pitch moment achievable by the feedforward control. The differential calculation unit 20 calculates a difference between a signal of an actual pitch rate, which is provided by the pitch rate sensor 11 was determined, and the corrected value of the target pitch rate as an error that deviates from the target value. The FB control unit 21 calculates a target pitching moment that the feedback control is to achieve according to the signal error (error deviation from the target value) from the differential calculation unit. 20 The FB control unit 21is trained to output the target pitching moment according to the aforementioned error as a PID control unit.

[0043] The FF control unit 19 This is a control unit that sets a model characteristic curve of a pitching moment to a pitching rate as a secondary vibration model, calculates a transfer function, and uses the inverse function of the transfer function. In particular, the equation of motion of a pitching motion can be obtained as the following equation 1. In this equation, Q represents a pitch angle, Ix a pitching inertia, Kx a pitching stiffness, Cx a pitching damping coefficient, and Mx a pitching moment. [EQUAL 1] Ix Q.. = –Kx Q – Cx Q. + Mx

[0044] The transfer equation from a pitching moment to a pitching rate is obtained from equation 1 in the form of the following equation 2, based on which the transfer function from a pitching rate to a pitching moment can be obtained as the following equation 3. [EQUAL 2] Q / Mx = S / (Ix·S 2 + Cx·S + Kx) [EQUAL 3] Mx / Q = (Ix·S 2 + Cx·S + Kx) / S

[0045] Fig. 5 and Fig. Figure 6 shows Bode plots that represent this transfer function. In particular, in Fig. 5 a characteristic curve 27 a gain characteristic curve and a characteristic curve 28 represents an integration characteristic curve. In Fig. 6 represents a characteristic curve 29 a phase characteristic curve of the transfer function and a characteristic curve 30 represents an integration characteristic curve.

[0046] The average value calculation unit 22 , which are in the control unit 13 The target pitching moment, which is trained by the FF control unit, is added. 19 was calculated and the target pitching moment, which is determined by the FB control unit 21 was calculated, and this value is given as the target pitching moment Ma to the target damping force calculation unit. 23 , which is intended as a subsequent stage.

[0047] As in Fig. Figure 7 shows how the target damping force calculation unit is calculated when the target pitching moment Ma is input. 23 the target damping forces of the respective wheels (i.e., the front left and right wheels) 2 and the rear left and right wheels 3 ) according to the target pitching moment Ma in a distributive manner. In particular, a block divides 23A the target damping force calculation unit 23The target pitching moment Ma is divided into four moments to distribute them evenly across the respective wheels. A next block 23B calculates a target damping force F FR of the front right wheel 2 by dividing the uniformly distributed moment (Ma / 4) by a distance lf of the front right wheel 2 to the weighted center on the front wheel side 2 A block 23C calculates a target damping force F FL of the front left wheel 2 by dividing the uniformly distributed moment (ma / 4) by the distance lf of the front left wheel 2 to the weighted center of the front wheel side 2 .

[0048] Furthermore, a block multiplies 23D the target damping force calculation unit 23 the moment Ma / 4 with “–1”, so that the front wheels 2 and the rear wheels 3The target damping forces exhibit opposing directions. Next, Block calculates 23E a target damping force F RR of the rear right wheel 3 , by replacing the moment (–Ma / 4), i.e., the uniformly distributed moment (Ma / 4) multiplied by –1, with a distance lr from the rear right wheel 3 to the weighted center on the rear wheel side 3 is shared. A block 23F calculates a target damping force F FL of the rear left wheel 3 by dividing the moment (–Ma / 4), that is, the uniformly distributed moment (Ma / 4) multiplied by –1, by the distance lr from the rear left wheel 3 to the weighted center on the rear wheel side 3 .

[0049] The damping value calculation unit 24applies computational processing (especially calculation based on a momentary characteristic map) by dividing the target damping forces F FR , F FL , F RR , F RL the respective wheels, which are controlled by the target damping force calculation unit 23 output by the relative velocity signal 15 and calculates the damper instruction values ​​that are sent to the actuators (not shown) of the respective variable damping force dampers. 6 and 9 The values ​​are output as electrical current values. Subsequently, the damping force characteristics of the respective variable damping force dampers are calculated. 6 and 9 on the respective wheels (the front left and right wheels) 2 and the rear left and right wheels 3) variable in a continuous or stepped manner, comprising a multitude of stages, controlled between the hard side and the soft side according to the electrical current values ​​(damper instruction values) supplied to the actuators.

[0050] The variable damping force dampers 6 and 9 on the respective wheels (the front left and right wheel) 2 and the rear left and right wheels 3 ) form the pitching moment generation unit, which is an integral component of the present invention, together with the FF control unit 19 , the FB control unit 21 , the average value calculation unit 22 , the target damping force calculation unit 23 and the damper instruction calculation unit 24 , which, for example, in Fig. 2 is shown, off.

[0051] The vehicle body position control device according to the present embodiment is designed as described above. Next, the processing that the control unit performs will be described. 13 carries out to determine the position of the vehicle body 1 to control, as described.

[0052] If the vehicle enters a curve in a road 31 Once reached and the curve begins to turn, it is activated as in Fig. Figure 8 shows a driver operating the steering wheel according to the phases straight-ahead driving, transition cornering, normal cornering, transition cornering, and straight-ahead driving in that sequence. At this point, the driver of the vehicle operates the steering wheel to adjust the steering angle according to the characteristic curve. 32 , as in Fig. 9 shown, to change.

[0053] When the vehicle is traveling straight ahead, the steering angle is approximately zero and is held in a neutral position. As the vehicle enters the transition curve, the steering angle is increased by the required amount. When the vehicle begins the normal turn, the steering angle is held at essentially a constant angle to maintain the required angle. Subsequently, as the vehicle enters the transition curve, the driver steers to return the steering angle to its normal position. When the vehicle returns to straight ahead, the steering angle is approximately zero and is held in the neutral position. This is similar to a characteristic curve. 33 indicated, which in Fig. As shown in 9, the lateral acceleration that is present in the vehicle structure 1 is generated according to the change in the characteristic curve 32The steering angle is changed and is essentially increased and decreased proportionally to it, similar to a characteristic curve. 34 , which in Fig. Figure 9 shows, indicating, the roll angle of the vehicle body. 1 also according to the changes in the characteristic curve 32 of the steering angle and the characteristic curve 33 the lateral acceleration is changed and essentially increased and decreased proportionally.

[0054] Characteristic curves 35 , 36 and 37 in Fig. Figure 9 shows the characteristic curves of the pitch angle, roll rate and pitch rate of the vehicle body. 1 each one. 36 the roll rate is referred to as the characteristic curve, which is obtained by differentiating the characteristic curve 34 the roll angle arises. Furthermore, the characteristic curves describe 35' and 37' , which are indicated by double-dashed lines in Fig. Figure 9 shows characteristic curves of the pitch angle and pitch rate in a comparative example (for example, the related technique discussed in Japanese patent application publication no. 2007-170590).

[0055] In the present embodiment, relative to the characteristic curve 34 of the roll angle, which in Fig. The characteristic curve is shown in section 9. 35 The pitch angle, for example, is controlled to be reduced during normal cornering and to exhibit a negative value during transition cornering. In other words, the relationship between the roll angle and the pitch angle is set as a proportional relationship that exhibits hysteresis, as shown by the characteristic curve. 38 depicted, which in Fig. 10 is shown.

[0056] Furthermore, the comparison example is designed to increase the pitch angle according to the roll angle, as with the characteristic curve.39 , which in Fig. Figure 11 indicates this. Therefore, the characteristic curve should 35' The pitch angle of the comparison example can generate a pitch angle of one degree according to the roll angle even during normal cornering, as shown by the two-dashed line in Fig. Figure 9 illustrates what can cause the driver to have an uncomfortable ride in the vehicle.

[0057] Therefore, the first embodiment of the present invention is designed to obtain a target pitch rate proportional to a roll rate, for example, as with the characteristic curve 26 in Fig. Figure 4 shows the damping force characteristics of the variable damping force dampers. 6 and 9 to control, which are arranged on the respective wheels (the front left and right wheel) 2 and the rear left and right wheels 3) in order to achieve the target pitch rate, thereby generating a corresponding pitching moment on the vehicle body.

[0058] In this way, adjusting the pitch rate and roll rate while the vehicle is cornering, in order to obtain a proportional relationship between them, can control the rotational axis of the vehicle body. 1 to prevent wobbling in order to improve steering feel. Furthermore, the first embodiment calculates a target pitch rate according to a roll state and controls the dampers to generate a pitching moment on the vehicle body in order to obtain the target pitch rate. Therefore, the roll rate and the pitch rate are set in a proportional relationship, and the vehicle is kept in a constant downward pitching state by reversing the sign of the roll rate, thereby controlling the rotational axis of the vehicle body. 1 It stabilizes the body and improves the feeling of instability.

[0059] Next we will show Fig. 1 and Fig. 12. A second embodiment of the present invention. The second embodiment is characterized in that it is designed to calculate a target pitching moment from a steering angle and a vehicle speed using a vehicle model and to control the position of the vehicle body without using a roll rate sensor and a pitch rate sensor. Furthermore, the second embodiment was designed not only to generate a pitching motion to stabilize the axis of rotation, but also to prevent roll behavior. In the following description of the second embodiment, similar components are designated with the same reference numerals as those in the first embodiment described above and are not described again.

[0060] Reference symbols used in the drawings 41a steering angle sensor that is attached to the vehicle body 1 is arranged. The steering angle sensor 41 determines a steering angle (which corresponds to a front wheel steering angle δ). f (corresponds to which will be described later), when a driver of the vehicle operates the steering wheel, for example while cornering, and sends the detected signal to a control unit. 43 from which will be described later.

[0061] Reference sign 42 refers to a vehicle speed sensor that is attached to the vehicle body 1 is arranged. The vehicle speed sensor 42 For example, it determines the vehicle's speed (which corresponds to the vehicle speed V, described later) and sends the determined signal to the control unit. 43 from which will be described later.

[0062] Reference sign 43A control unit is a control device, such as a microcomputer. The input side of the control unit 43 for example, with the steering angle sensor 41 and the vehicle speed sensor 42 connected. The output side of the control unit 43 is with, for example, actuators (not shown) of an FR damper (the variable damping force damper). 6 of the front right wheel), an FL damper (the variable damping force damper) 6 of the front left wheel), an RR damper (the variable damping force damper) 9 of the rear right wheel) and an RL damper (the variable damping force damper). 9 connected to the rear right wheel.

[0063] As in Fig. The control unit is shown in section 12. 43 a vehicle model unit 44 , a differentiation unit 45, Target damping force calculation units 46 and 47 for roll control, sign reversal units 48 and 49 , an absolute value calculation unit 50 , a target pitching moment calculation unit 51 , a unit of calculation for uniform distribution 52 , Target damping force calculation units 53 , 54 , 55 and 56 the respective wheels, adding units 57 and 58 , subtraction units 59 and 60 , damper instruction value calculation units 61 , 62 , 63 and 64 for the respective wheels, a phase adjustment filter 100 and a relative velocity estimation unit 101 .

[0064] In the present embodiment, the control unit calculates 43 the vehicle model unit 44the lateral acceleration by estimating the lateral acceleration based on a steering angle signal from the steering angle sensor 41 was determined, and a vehicle speed signal provided by the vehicle speed sensor 42 determined according to the procedure described below. The control unit then calculates 43 The target pitching moment is achieved by performing feedforward control (FF control) based on the estimated lateral acceleration, thereby improving the roll feel.

[0065] First, the vehicle modeling unit estimates 44 the lateral acceleration ay from a steering angle (the front wheel steering angle δ) f) and a vehicle speed V using the vehicle model expressed by the following equation (4). The lateral acceleration ay can, for example, be obtained from equation (4), assuming a linear model of the vehicle without the dynamic properties reflected therein. In equation (4), V represents a vehicle speed (m / s), A represents a stability factor (S). 2 / m 2 ) dar, δ f represents a front wheel steering angle (rad) and L represents a wheel base (m). [EQUAL 4] Ay = {1 / (1 + AV 2 )} × (V 2 / L) × δ f

[0066] The dynamics are then adjusted using an input of a steering angle to generate lateral acceleration and a roll angle using the phase adjustment filter. 100 compensated. Next, the differentiation unit differentiates. 45The lateral acceleration is used to calculate the lateral jerk. Since the lateral jerk essentially corresponds to a roll state, the target damping force calculation unit is multiplied in the next stage. 46 and 47 The program calculates the lateral jerk, which correlates with the roll rate, with an Fr amplification of the front right wheel and an Rr amplification of the rear right wheel, and outputs the calculated values ​​as target damping forces for roll prevention of the front right and rear right wheels. The sign reversal units 48 and 49 multiply the target damping forces for roll prevention by “–1”, so that the target damping forces of the front left wheel and the rear left wheel have the opposite sign to the wheels on the right side.

[0067] The relative velocity estimation unit 101estimates the relative speed of the respective wheels using the lateral jerk provided by the differential unit 45 It is calculated from. The absolute value calculation unit. 50 It calculates an absolute value |u| of the lateral jerk. The target pitching moment calculation unit. 51A target pitching moment My is calculated by multiplying the absolute value |u| of the lateral jerk by a gain “Kroll2r”. It should be noted that the target pitching moment Ma is calculated proportionally to the lateral acceleration, since the transfer function of a pitch rate to a pitching moment, used in the first embodiment, can be adjusted to be proportional to a roll angle obtained by integrating a roll rate, as the phase characteristic of the transfer function is -90 degrees below a control input frequency of 1 Hz or less, which is a target range for this processing, and the target pitching moment Ma can be proportional to the lateral acceleration, since the roll angle is correlated with the lateral acceleration.

[0068] Next, after receiving the target pitching moment Ma, the calculation unit divides for an even distribution. 52The target pitching moment Ma is divided into four moments and distributed evenly to the respective wheels in order to provide target damping forces at the respective wheels accordingly (i.e., the front left and right wheel and the rear left and right wheel). 2 The following units are the target damping force calculation units. 53 and 54 , calculate the damping forces for the front right wheel 2 and the front left wheel 2 , which will correspond to the pitch generation by applying the uniformly distributed moment (Ma / 4) through the distance lf to the weighted center of the front wheel side 2 Divide. Furthermore, calculate the target damping force calculation units. 55 and 56 the target damping forces for the rear right wheel 3 and the rear left wheel 3 by dividing the evenly distributed moment (Ma / 4) by the distance lr to the weighted center of the rear wheel side3 .

[0069] Next, the adding units add 57 and 58 the target damping forces for roll prevention, which are determined by the target damping force calculation units 46 are output and the target damping forces for pitch generation, which are determined by the target damping force units. 53 and 54 to be output to determine the total damping forces as the target damping force for the front right wheel and the target damping force for the front left wheel. 2 to calculate. Furthermore, since the front wheels 2 and the rear wheels 3 Subtraction units should have nodding components with opposite signs. 59 and 60 the target damping forces for pitch generation, which are determined by the target damping force calculation units 55 and 56output from the target damping forces for roll prevention, which are determined by the target damping force calculation unit 47 The resulting damping forces are output to be used as the target damping force for the rear right wheel. 3 and the target damping force for the rear left wheel 3 to calculate.

[0070] Subsequently, the target damping forces for the respective wheels are calculated by adding and subtracting between the target damping forces calculated for roll prevention and the target damping forces calculated for pitch generation in this way, the damping instruction value calculation units. 61 , 62 , 63 and 64 output the required electrical current values ​​from a pre-stored damper characteristic map, based on these target damping forces and the relative velocities specified in the relative velocity estimation unit.101 were estimated. In particular, the damping instruction value calculation units calculate 61 , 62 , 63 and 64 Damper instruction values, as electrical values, which are sent to the actuators (not shown) of the FR damper (the variable damping force damper). 6 of the front right wheel), of the FL damper (the variable damping force damper) 6 of the front left wheel), of the RR damper (the variable damping force damper) 9 of the rear right wheel) and the RL damper (the variable damping force damper) 9 to be spent.

[0071] Next, the variable damping force dampers are installed. 6 and 9 the respective wheels (front left and right wheel) 2 and rear left and right wheel 3) variably controlled, so that the damping force characteristics vary continuously or in a stepped manner, encompassing a multitude of steps between the hard side and the soft side according to the electrical current values ​​(damper instruction values) supplied to the actuators. The variable damping force dampers 6 and 9 the respective wheels (the front left and right wheel) 2 and the rear left and right wheels 3 ) form the pitching moment generation mechanism of the pitching moment generation unit, which is a defining moment of the present invention. Furthermore, they form the absolute value calculation unit. 50 and the target pitching moment calculation unit 51 of the in Fig. 12 control units shown 43 the target pitch rate calculation unit or the target pitch moment calculation unit.

[0072] Therefore, the second embodiment designed in this way can also generate an ideal relationship between pitch and roll behavior, thereby improving the feeling a driver has while driving. In particular, the second embodiment can control the attitude of the vehicle body. 1 based on only one steering angle and one vehicle speed without using a roll rate sensor and a pitch rate sensor.

[0073] As a result, it is possible to reduce the number of sensors required, leading to cost reduction and system simplification. Furthermore, it is possible to control the vehicle body's position, not only to generate pitching motion for stabilizing the axis of rotation, but also to prevent roll, thereby improving the perceived roll.

[0074] Next, Fig. Figure 13 represents a third embodiment of the present invention. This third embodiment is characterized in that the actuator for controlling the position of the vehicle body is embodied by an active suspension capable of generating a thrust force itself, instead of a semi-active actuator. In the following description of the third embodiment, similar components are designated by the same reference numerals as those in the first embodiment described above and are not described again.

[0075] Referring to Fig. 13, designates reference mark 71 a control unit such as a control device that uses the present embodiment. The control unit 71 is essentially the same as the control unit 13 designed in the first embodiment. The input side of the control unit. 71 is equipped with, for example, the roll rate sensor 10, the pitch rate sensor 11 and the lateral acceleration sensor 12 connected. The roll angle signal 14 , which in Fig. Figure 13 is shown and is calculated from a lateral acceleration signal provided by the lateral acceleration sensor. 12 was determined.

[0076] However, the control unit differs. 71 in the present embodiment, from the first embodiment in view of its output side, which is equipped with, for example, an active suspension (an electromagnetic damper). 74 (which will be described later) is connected to a device capable of generating thrust independently. Furthermore, the control unit includes 71 the reinforcement 16 , the investigation unit 17 , the multiplication unit 18 , the FF control unit 19 , the difference calculation unit 20 , the FB control unit 21 , the average value calculation unit22 , a target pitching moment calculation unit 72 and an electromagnetic damper control amount calculation unit 73 for each wheel. The target pitching moment calculation unit differs among these units. 72 and the electromagnetic damper control amount calculation unit for each wheel 73 from the units of the first embodiment.

[0077] Reference sign 74 This refers to a set of electromagnetic dampers (four dampers) located at each of the vehicle's wheels. The electromagnetic dampers 74 are achieved through active suspensions, each located on, for example, the front left and right wheels. 2 and the rear left and right wheels 3 are arranged, designed and act to generate thrust forces for vertical raising and lowering of the vehicle body 1at the respective wheels according to control signals from each electromagnetic damper control unit - amount calculation unit for each wheel 73 to produce.

[0078] After the average value calculation unit 22 a target pitching moment, which is controlled by the FF control unit 19 was calculated, and a target pitching moment, which is determined by the FB control unit. 21 The calculated values, added to obtain an average, are used to calculate the target pitching moment calculation unit. 72 of the control unit 71 a calculation to determine the target pitching moment at the respective wheels (i.e., the front left and right wheels) 2 and the rear left and right wheels 3 ) to distribute according to the calculated average value. The electromagnetic attenuation control amount calculation unit then calculates 73 electromagnetic damper control amounts for each wheel, so that the electromagnetic dampers 74can generate thrust forces at the respective wheels that correspond to the target pitching moments distributed to the respective wheels, and individually outputs the control signals indicating the calculated control amounts to the respective electromagnetic dampers.

[0079] Therefore, the third embodiment, designed as described above, can also establish an ideal relationship between pitch and roll behavior, thereby improving the driver's experience. Specifically, the third embodiment can generate a pitch rate proportional to a roll rate by calculating target thrust forces for the respective wheels and generating thrust forces at the active suspensions according to these target values. This makes it possible to control the rotational axis of the vehicle body. 1 to stabilize and improve roll behavior.

[0080] Furthermore, it shows Fig. 14 A fourth embodiment of the present invention. The fourth embodiment is characterized in that, compared to the first embodiment which uses feedback control at a pitch rate, feedforward control is used at a pitch rate. In the following description of the fourth embodiment, similar components are designated with the same reference numerals as those in the first embodiment described above and are not described again.

[0081] In Fig. 14 designates reference numeral 111A longitudinal acceleration determination unit (longitudinal acceleration state determination unit) for determining longitudinal acceleration. The longitudinal acceleration determination unit can be embodied, for example, by a longitudinal acceleration sensor or a unit for measuring the difference value of a reading from a vehicle speed sensor. Alternatively, the longitudinal acceleration determination unit can be embodied by a unit for estimating longitudinal acceleration based on, for example, the amount of pressure applied to a driver's brake pedal or the pressure in a wheel cylinder of a braking system.

[0082] Reference sign 112 This refers to a pitch rate estimation unit (pitch state estimation unit) used to estimate a generated pitch rate. The pitch rate estimation unit 112 estimates a generated pitch rate based on the determination result of the aforementioned longitudinal acceleration determination unit.

[0083] The pitch rate generated due to longitudinal acceleration is then subtracted from a target pitch rate determined by the multiplier unit. 18 The output is displayed, and the difference to the target pitch rate is sent to the FF control unit. 19 issued to determine the damping forces of the variable damping force dampers 6 ( 9 ) using a target damping force calculation unit 23 and a damper instruction value calculation unit 24 to adjust in order to obtain the target damping rate.

[0084] As a result, similar effects to those in the first embodiment can be achieved with the fourth embodiment. Furthermore, pitching generated by brake application or the like is taken into account by the feedforward control unit, and an excess or deficiency of the pitch rate is controlled by the variable damping force dampers. This can reduce the pitch control amount that relies on the variable damping force dampers, thereby correspondingly increasing the roll control amount.

[0085] It should be noted that, while a longitudinal acceleration determination unit is used as the longitudinal acceleration state determination unit in the embodiment described above, the longitudinal acceleration state determination unit can be embodied by a unit for determining a longitudinal acceleration state using a rate of change of longitudinal acceleration.

[0086] Although the above embodiment has been further described, assuming that a roll rate and roll angle can be determined, a roll rate and roll angle can be estimated based on a lateral acceleration calculated from a steering angle and a vehicle speed, or from a signal value output by a lateral acceleration sensor.

[0087] The first and third embodiments were described based on an example that determines a roll rate and a pitch rate using appropriate sensors. However, the present invention is not limited to this. For example, a roll rate and a pitch rate can be calculated using three or more vertical acceleration sensors arranged in the vehicle body.

[0088] Furthermore, the relative velocity for the first, second, and third embodiments can be obtained by differentiating a reading from the vehicle height sensor, or by calculating a relative acceleration from readings from, for example, the unsprung acceleration sensor and the sprung acceleration sensor, and then integrating these values. Alternatively, since the movement of the unsprung side is nearly zero when the vehicle is traveling on a flat road surface, the relative velocity can be a velocity on the sprung side, calculated by integrating a reading from the acceleration sensor on the sprung side. The second embodiment also uses a lateral acceleration estimated from a steering angle and a vehicle speed; however, the lateral acceleration can be determined by a lateral acceleration sensor.Furthermore, the other signals can also be obtained through any calculation method.

[0089] Furthermore, the first embodiment was described based on an example which includes a roll state signal from the roll rate sensor. 10 was determined using the gain specified for each vehicle (for example, the gain determined by the characteristic curve). 26 in Fig. 4 is shown) multiplied and a pitch rate corresponding to the roll rate at that time, according to the characteristic curve 26 as a target pitch rate. However, the present invention is not limited to this. For example, a non-linear characteristic curve defined by a curve can be used as the characteristic curve. 26 in Fig.4. A target pitch rate can be determined, and a target roll rate can be calculated so that it does not increase linearly with the degree of roll. The above also applies to the second and third embodiments.

[0090] Next, advantageous effects provided by the embodiments described above will be described. That is, according to one embodiment of the present invention, the target pitch rate calculation unit calculates a target pitch rate proportional to a roll rate, and the pitch moment generation unit controls the dampers to generate a pitch moment on the vehicle body in order to achieve the target pitch rate. Setting a pitch rate and a roll rate to achieve a proportional relationship between them in this way can prevent the rotational axis of the vehicle body from wobbling, thereby improving steering feel.

[0091] Furthermore, according to one embodiment of the present invention, the target pitch rate calculation unit is configured to calculate a target pitch rate, such that the degree of forward dive of the vehicle body at the front is increased according to the degree of roll rate of the vehicle body. As a result, the front wheel side is lowered when the vehicle is, for example, cornering, in order to implement roll behavior accompanied by forward pitch, thus improving the feeling a driver has while cornering.

[0092] According to one embodiment of the present invention, the pitching moment generation unit comprises the target pitching moment calculation unit (for example, a quadric model and a differentiator) for calculating a target pitching moment from a target pitch rate using the vehicle model and the target pitching moment mechanism (for example, a semi-active suspension or an active suspension) for generating a pitching moment such that the pitching moment of the vehicle body reaches the target pitching moment.

[0093] As a result, it is possible to obtain lateral acceleration readings when the vehicle is cornering, using only the steering angle sensor and the vehicle speed sensor, without the need for, for example, a roll rate sensor and a pitch rate sensor. This reduces the number of sensors required, lowers costs, and simplifies the system. Furthermore, it is possible to control the vehicle's body position, not only to generate pitch for stabilizing the axis of rotation but also to prevent roll, thus achieving improved roll feedback.

[0094] Furthermore, according to one embodiment of the present invention, the system comprises the pitch rate detection unit for determining the pitch rate of the vehicle body and the pitch moment generation unit for generating a pitch moment on the vehicle body in order to reduce the difference between the determined pitch rate and the target pitch rate. As a result, it is possible to generate a pitch moment on the vehicle body using the pitch moment generation unit to reduce the difference between the actual pitch rate of the vehicle body, as determined by the pitch rate detection unit, and the target pitch rate.

[0095] Furthermore, according to the present embodiment, the vehicle comprises at least four wheels, and the pitching moment generation unit includes adjustable damping shock absorbers arranged at the respective wheels and capable of adjusting the damping characteristics. Therefore, the pitching moment generation unit is designed to adjust the pitching moment of the vehicle body by adjusting the damping characteristics.

[0096] Furthermore, according to one embodiment of the present invention, the vehicle comprises at least four wheels. The pitching moment generation unit includes active suspensions arranged at the respective wheels to apply vertical thrust forces to the vehicle body and the wheels, and is configured to apply a pitching moment to the vehicle body by adjusting the vertical forces. As a result, target thrust forces of the respective wheels are calculated, and thrust forces of the active suspensions are generated according to the target values ​​to enable the generation of a pitch rate proportional to the roll rate, thereby stabilizing the rotational axis of the vehicle body and improving roll feedback.

[0097] Furthermore, according to one embodiment of the present invention, the front of the vehicle is lowered, generating a pitch angle which reduces the roll rate. The reason is as follows: If no pitch angle is generated, the roll rate is the difference between a pure roll angle (an angle relative to the horizontal direction of travel). On the other hand, if a pitch angle is generated, the roll rate is the result of subtracting the difference between a roll angle and an angular velocity (generated by a yaw angle, an angular velocity in the vertical direction). This results in the pitch angle and the roll rate being in a compensating relationship, thus reducing the roll rate in accordance with the generation of the pitch angle.

[0098] The roll rate can be approximately calculated using the following equation: (Roll rate) = (Difference in roll angle) – (Yaw rate) × (Pitch angle).

[0099] The embodiments described above perform calculations using various values ​​such as roll angle, roll rate, and pitch rate. However, the control unit does not need to receive these values ​​during the calculations and can use an approximate or estimated value. Furthermore, for example, when determining the sign of a roll angle, the control unit can use another value that has only one sign, which changes in the same way as the roll angle. Alternatively, a map can be used instead of calculations.

[0100] The embodiments described above control roll; however, in practical use of the present invention, roll control can be combined with bouncing control, such as a skyhook control. In this case, for example, control can be achieved by averaging a target damping force from the bouncing control and a target damping force of the present invention. Alternatively, priority can be determined based on a steering angle; in particular, the target damping force of the bouncing control can be prioritized when the steering angle is small, while the control of the present invention can be prioritized when the steering angle is large.

[0101] Furthermore, in the embodiments described above, the roll state detection unit determines a roll rate; however, this does not limit the present invention. The roll state detection unit can determine a roll angle or a rate of change of a roll angular velocity. The embodiments described above also use a pitch rate as a pitch state or a target pitch state; however, this does not limit the present invention. Instead, a pitch angle or a rate of change of a pitch rate can be used as a pitch state and a target pitch state.

[0102] As mentioned above, according to the embodiments of the present invention, it becomes possible to obtain an ideal coupling relationship between pitching behavior and roll behavior, thereby improving the feeling that a driver has while driving.

[0103] Although only some exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily recognize that many modifications to these exemplary embodiments are possible without substantially departing from the new teaching and advantages of this invention. Accordingly, it is intended that all such modifications be included within the scope of protection of this invention.

[0104] The present invention claims priority from Japanese patent application No. 2010-170247, filed on July 29, 2010. The entire disclosure of Japanese patent application No. 2010-170247, filed on July 29, 2010, comprising description, claims, drawings, and abstract, is incorporated herein by reference.

[0105] The entire disclosure of the Japanese patent application publications numbered 2007-290650 and 2007-170590, including the description, claims, drawings and abstract, is incorporated herein by reference in its entirety. QUOTES INCLUDED IN THE DESCRIPTION

[0106] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0107] JP 2007-290650 [0002, 0009, 0105] JP 2007-170590 [0003, 0054, 0105] JP 2010-170247 [0104, 0104] Cited non-patent literature

[0108] “Improved roll perception based on visual sensitivity”, written by Hideki Sakai and 5 others, published in the TOYOTA Technical Review Vol. 55 No. 1 (November 2006) pages 20 to 24

[0006] “A Study of Vehicle Roll Behavior (Suspension Technology to Improve Roll Sensation)”, written by Kenji Kawagoe, published in the Journal of the Society of Japanese Automotive Engineers (Automotive Technology) Vol. 51 No. 11 (1997) Pages 20 to 24

[0007] “Vehicle Position Measurement Method with GPS”, written by Hitoshi Fukuba and 2 others, published in the Technical Overview by Matsuda No. 20 (2002) pages 130 to 138

[0008]

Claims

[1] Vehicle body position control device for controlling the position of a vehicle body of a vehicle, the device comprising: a target pitch state calculation unit ( 16 , 17 , 18 ; 50 ), which is designed to calculate a target pitch state as a target value of a pitch state of the vehicle body according to a roll state of the vehicle body; and a pitching moment generation unit ( 19 , 21 , 22 , 23 , 24 , 6 , 9 ; 51 , 52 , 53 – 56 , 61 – 54 , 6 , 9 ; 19 , 21 , 22 , 72 , 73 , 74 ), which is designed to generate a pitching moment applied to the vehicle body so that the pitching state of the vehicle body approaches the target pitching state. [2] Vehicle body position control device according to claim 1, wherein The pitch state is a pitch rate and the roll state is a roll rate, and where the target pitch state calculation unit calculates the target pitch rate, so that a forward dive of the vehicle body is increased according to the degree of the roll rate of the vehicle body. [3] Vehicle body position control device according to claim 1 or 2, wherein the pitching moment generation unit is a target pitching moment calculation unit ( 51 ), which is designed to calculate a target pitching moment from the target pitching state using a vehicle model, and a pitching moment generation mechanism ( 6 , 9 ), which is designed to generate a pitching moment so that the pitching moment of the vehicle body approaches the target pitching moment. [4] Vehicle body position control device according to claim 1 or 2, further comprising a pitch state detection unit (11 ), which is trained to determine the pitching state of the vehicle body, wherein the pitching moment generation unit generates a pitching moment which is to be applied to the vehicle body in order to reduce a difference between the determined pitching state and the target pitching state. [5] Vehicle body position control device according to any one of claims 1 to 4, wherein the vehicle comprises at least four wheels, wherein the pitching moment generating unit includes an adjustable damping force shock absorber ( 6 , 9 ) includes a system capable of adjusting a damping force characteristic curve, with the shock absorber being arranged at each of the wheels, and wherein the pitching moment generation units adjust the pitching moment to be applied to the vehicle body by adjusting the damping force characteristic. [6] Vehicle body position control device according to any one of claims 1 to 4, wherein the vehicle comprises at least four wheels, wherein the pitching moment generation unit is an active suspension ( 74 ) comprising, which is designed to apply a vertical force to the vehicle body and the wheel, with the active suspension being arranged at each of the wheels, and the pitching moment generation unit applies the pitching moment to the vehicle body by adjusting the vertical force. [7] Vehicle body position control device according to claim 1, wherein the roll state of the vehicle body and the pitch state of the vehicle body are obtained from a steering angle and a vehicle speed. [8] Vehicle body position control device according to claim 1, wherein pitch state is a pitch rate. [9] Vehicle body position control device according to claim 1, wherein the pitching state is a pitching angle.

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