JP2010112793A - Measurement method of axis line slope of acceleration sensor and detection method of vertical acceleration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply measure an axis line slope of a vertical acceleration sensor, and to accurately detect a vertical acceleration by the vertical acceleration sensor having a slanted axis line. <P>SOLUTION: A vehicle body is positioned in two postures having different pitch and roll quantities, output values of the vertical acceleration sensors 94 are obtained in each of the postures, and the slope quantities ρ<SB>x</SB>, ρ<SB>y</SB>, ρ<SB>z</SB>of the axis line SL of the sensor are calculated based on these obtained output values, and the pitch and roll quantities in each of the postures. In the case where the slope of the sensor axis line is known, the vertical acceleration is calculated so as to correct the output value of the sensor based on the slope, the longitudinal acceleration and the lateral acceleration of the vehicle body. Also, based on the output values of the three vertical acceleration sensors, the slopes of these three sensors, and the pitch and roll quantities of the vehicle body, the vertical acceleration of the sites of the vehicle body where the three sensors are attached is calculated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of measuring the amount of inclination of an axis of an acceleration sensor for detecting the acceleration of the vehicle body, and a method of detecting vertical acceleration of the vehicle body by an acceleration sensor having an inclined axis.

In recent years, vehicles equipped with an electromagnetic shock absorber, that is, vehicles equipped with an electromagnetic suspension system have been studied. In many of the electromagnetic suspension systems under consideration, the operation of each electromagnetic shock absorber corresponding to each wheel is controlled based on the detection value of each of the sprung vertical acceleration sensors provided corresponding to the four wheels. . Therefore, in order to perform appropriate electromagnetic shock absorber control, it is desired that the output value of the vertical acceleration sensor be accurate. Thus, for example, the following patent document describes a technique for correcting the output values of the vertical acceleration sensors in consideration of variations in output values output from a plurality of vertical acceleration sensors attached to the vehicle body.
JP 2000-283996 A

  When the direction of the acceleration that is detected by the acceleration sensor, that is, the direction of the acceleration scheduled to be detected by the acceleration sensor is defined as the “scheduled detection direction” of the sensor, the planned detection direction and the axis of the acceleration sensor The acceleration sensor cannot accurately detect the acceleration in the planned detection direction when it is attached to the vehicle body in a state that does not match the direction of. The inventor of the present application has obtained the knowledge that if the inclination amount of the acceleration sensor can be grasped, the acceleration in the planned detection direction can be accurately detected by correcting the output value of the acceleration sensor based on the inclination amount. The present invention is based on the knowledge, and an object of the present invention is to provide a method for easily measuring the amount of inclination of an acceleration sensor, and the vertical acceleration is calculated based on the grasped amount of inclination of the acceleration sensor. It is an object of the present invention to provide a method for accurate detection.

  The acceleration sensor axis inclination measuring method of the present invention is a method of measuring the axis inclination of an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis, and solves the above problem In order to do this, (a) a vehicle body is set to a first posture, and a first sensor output value acquisition step of acquiring a first sensor output value that is an output value of the acceleration sensor in that posture; And a second sensor output value acquisition step of acquiring a second sensor output value, which is an output value of the acceleration sensor in the attitude, in a second attitude that is different from the first attitude in the roll amount, and (c) the first Based on the 1 sensor output value and the second sensor output value, and the roll amount and the pitch amount in each of the first posture and the second posture, the amount of inclination of the axis of the acceleration sensor is calculated. Characterized in that it comprises a sensor inclination amount calculating step.

  A first vertical acceleration detection method of the present invention is a vertical acceleration detection method using an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis, and solves the above problem. For this purpose, (a) a step of recognizing the amount of inclination of the axis of the acceleration sensor, (b) a step of acquiring longitudinal acceleration and lateral acceleration occurring in the vehicle body, (c) an output value of the acceleration sensor, And a step of calculating vertical acceleration at a site where the acceleration sensor is attached based on the recognized amount of inclination of the axis of the acceleration sensor and the acquired longitudinal acceleration and lateral acceleration.

  Furthermore, in the second vertical acceleration detection method of the present invention, each of the three or more parts is attached to the vehicle body at three or more parts, and each of the three or more parts is detected by three or more acceleration sensors that detect acceleration in the axial direction. In order to solve the above-mentioned problem, (a) a step of recognizing the inclination amount of each of the three or more acceleration sensors, and (b) a pitch amount and a roll amount of the vehicle body And (c) the output value of each of the three or more acceleration sensors, the amount of inclination of the recognized axis of each of the three or more acceleration sensors, and the obtained pitch amount and roll amount of the vehicle body. And calculating a vertical acceleration in at least one of the three or more parts.

  According to the acceleration sensor axis inclination measuring method of the present invention, the vehicle body is set to two different postures in each of the pitch amount and the roll amount, and the vehicle body is obtained by simple means such as acquiring the output value of the acceleration sensor in each posture. It is possible to measure the amount of inclination of the axis of the acceleration sensor attached to the. Further, according to the vertical acceleration detection method of the present invention, even when the axis of the vertical acceleration sensor is inclined and attached to the vehicle, if the amount of inclination of the axis of the acceleration sensor is grasped, the acceleration sensor is attached. It is possible to properly detect the vertical acceleration at the site.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention. Each of the following items (1) to (8) corresponds to each of claims 1 to 8.

(1) A method of measuring the amount of inclination of an axis of an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis,
A first sensor output value acquisition step of acquiring a first sensor output value, which is an output value of the acceleration sensor in the posture, with the vehicle body as a first posture;
A second sensor output value acquisition step of acquiring a second sensor output value, which is an output value of the acceleration sensor in the posture, in a second posture that is different from the first posture in pitch amount and roll amount;
A sensor tilt amount for calculating the tilt amount of the axis of the acceleration sensor based on the first sensor output value and the second sensor output value, and the roll amount and the pitch amount in each of the first posture and the second posture. A method for measuring the amount of tilt of an acceleration sensor axis including a calculation step.

  According to the acceleration sensor axis inclination measuring method of this section, the vehicle body is set to two different postures in each of the pitch amount and the roll amount, and the output value of the acceleration sensor is acquired in each posture. It is possible to measure the amount of inclination of the axis of the acceleration sensor attached to the vehicle body as the vertical acceleration sensor.

  The “acceleration sensor axis” (hereinafter sometimes referred to as “sensor axis”) in this section is a virtual line extending in the direction of acceleration actually detected by the acceleration sensor, in other words, detected by the acceleration sensor. It can be thought of as a line indicating the direction of possible acceleration. For example, when the acceleration sensor is attached to the vehicle body as a vertical acceleration sensor, since the acceleration in the vertical direction is a detection target, the acceleration sensor is attached to the vehicle body in a posture in which the sensor axis is directed in the vertical direction as the scheduled detection direction. .

  The “inclination amount of the axis of the acceleration sensor” in this section means the amount of inclination of the sensor axis with respect to the vehicle body when the acceleration sensor is attached to the vehicle body. For example, when the vehicle is stationary on a horizontal plane (hereinafter sometimes referred to as “standard state”), it can be considered as the amount of inclination of the sensor axis with respect to the planned detection direction of the acceleration sensor. Furthermore, the “inclination amount” can be considered as a concept including the direction of inclination, and the “inclination amount” can employ an index that also indicates the direction of inclination. For example, when the vehicle is in a standard state, the axis of the vehicle body extending in the front-rear direction of the vehicle is the “front-rear axis”, the axis of the vehicle body extending in the left-right direction, that is, the vehicle width direction is the “horizontal axis”, and the axis of the vehicle body extending in the vertical direction Is defined as “vertical axis”, the angle between each of these three axes and the sensor axis (hereinafter referred to as “front-rear axis angle”, “lateral axis angle”, “vertical axis angle”, respectively) In some cases, the inclination amount of the axis of the acceleration sensor can be obtained. According to such a representation, for example, when the acceleration sensor is a vertical acceleration sensor, when the axis is attached to the vehicle body in a direction that matches the vertical axis, the amount of inclination of the axis of the acceleration sensor is The front / rear axis angle and the horizontal axis angle are 90 °, and the vertical axis angle is 0 °. Further, instead of expressing with such three angles, for example, it can also be expressed by an angle formed by the projection line of the axis of the acceleration sensor with respect to the horizontal plane and the longitudinal axis or the horizontal axis, and an angle formed by the vertical axis. That is, the amount of inclination of the axis of the acceleration sensor can be represented by various parameters that can substantially represent the amount of inclination. Note that the amount of inclination of the axis of the acceleration sensor may not be expressed three-dimensionally, and may be expressed two-dimensionally, such as an angle with respect to the vertical axis in a plane perpendicular to the front-rear axis or the horizontal axis.

  “Pitch amount” and “roll amount” in this section can typically be expressed as angles formed by the front and rear axis, the horizontal axis, and the horizontal plane, that is, a roll angle and a pitch angle, respectively. For example, the pitch angle is a value calculated based on the difference between the distance between the front and rear body wheels (distance between the sprung springs) and the wheel base, and the roll angle is the left wheel side, right side A value calculated based on the difference between the distances between the vehicle body wheels on the wheel side (distance between the sprung springs and the unsprung springs) and the tread can be employed. It is not limited to the pitch angle and roll angle, but other parameters such as the difference between the vehicle wheel distances on the front wheel side and the rear wheel side, and the vehicle wheel distances on the left wheel side and the right wheel side. The pitch amount and the roll amount can also be obtained by the difference.

  “First posture” and “second posture” in this section are two postures having different pitch amounts and roll amounts, and one of the first posture and the second posture is at least a pitch and a roll. The posture which does not do one side may be sufficient. That is, the case where at least one of the pitch amount and the roll amount is 0 is included. In addition, as a means to implement | achieve a 1st attitude | position and a 2nd attitude | position, you may utilize apparatuses with which vehicles were equipped, such as the approach / separation force generator mentioned later, and also gives force from the vehicle exterior. A device may be used. For example, the vehicle body may be tilted by a device that places the vehicle on a certain table and tilts the table to tilt the vehicle.

  The method of calculating the tilt amount of the sensor axis is not particularly limited in its specific mode. For example, as described above, when the amount of tilt is represented by the paired longitudinal axis angle, the paired horizontal axis angle, and the paired vertical axis angle, three equations are created with these three angles as variables (unknown numbers). Then, by solving them as simultaneous equations, it is possible to calculate the three angles, that is, the amount of inclination of the sensor axis. More specifically, for example, when the vehicle body is not running, the acceleration acting on the vehicle body can be regarded as only the gravitational acceleration, and therefore the output of the vertical acceleration sensor in each of the first posture and the second posture. It is possible to create two equations for the values. Specifically, it is possible to create two equations that take into account the pitch amount and the roll amount in each posture. By solving the two equations and the equation based on the three-square theorem, that is, the equation in which the sum of the squares of the cosines of the three angles is 1, the three angles, that is, It is possible to calculate the inclination amount of the acceleration sensor.

  When a plurality of acceleration sensors are attached to the vehicle body as vertical acceleration sensors, the amount of inclination of the sensor axis line is calculated for each acceleration sensor by the above-described method. For all, it is possible to detect the amount of inclination of the sensor axis.

  (2) One of the first posture and the second posture is a posture in which the vehicle body is pitched and not rolled, and the other of the first posture and the second posture is a posture in which the vehicle body is rolled and pitched. The method for measuring the amount of tilt of the acceleration sensor axis according to item (1), wherein the posture is not in the position.

  According to the aspect of this section, in the first posture and the second posture, the vehicle body is inclined only in one of the pitch direction and the roll direction, so that the vehicle body can be easily inclined when acquiring the output value of the acceleration sensor. It can be carried out.

(3) A vehicle having the acceleration sensor attached to the vehicle body has four approaching / separating force generators that are provided corresponding to the four front, rear, left, and right wheels and generate a force for approaching and separating the wheels and the vehicle body. And
In the first sensor output value acquisition step and the second sensor output value acquisition step, the vehicle body is tilted by the operation of the four approach / separation force generators, and the first sensor output value and the second sensor output value are obtained. The acceleration sensor axis inclination measuring method according to (1) or (2), which is a step of obtaining.

  According to the aspect of this section, when tilting the vehicle body, no device other than the device mounted on the vehicle is required, so that the method for measuring the amount of inclination of the axis of the acceleration sensor is practical. can do. Specifically, for example, the posture in which the vehicle body is pitched by operating the four approaching / separating force generators so that the distance between the vehicle wheels on the front wheel side and the distance between the vehicle wheels on the rear wheel side are different from each other. In addition, the posture in which the vehicle body is rolled by operating the four approach / separation force generating devices so that the distance between the left and right vehicle body wheels and the distance between the left and right vehicle body wheels are different from each other. It can be. In addition, the specific configuration of the “approaching / separating force generator” in the aspect of this section is not particularly limited. For example, it may be a device mainly composed of a hydraulic suspension cylinder, or a device mainly composed of an actuator operated by electric power, such as an electromagnetic shock absorber described later.

  (4) Each of the four approach / separation force generators is an electromagnetic shock absorber that has an electromagnetic motor and generates resistance force against approach / separation between the wheel and the vehicle body based on the force of the electromagnetic motor. (3) The method for measuring an axial inclination amount of the acceleration sensor according to item (3).

  In suspension systems equipped with electromagnetic shock absorbers currently being studied, each electromagnetic shock absorber is controlled based on the detection value of a sprung vertical acceleration sensor attached to the vehicle body corresponding to each wheel. ing. Therefore, in such a suspension system, since the vehicle body can take the first posture and the second posture by a device already provided in the vehicle, these acceleration sensors can be provided without providing a special device in the vehicle. It is possible to measure the amount of inclination of the axis.

(5) A method for detecting vertical acceleration by an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis,
Recognizing the amount of inclination of the axis of the acceleration sensor;
Obtaining the longitudinal acceleration and lateral acceleration occurring in the vehicle body;
Calculating the vertical acceleration at the site where the acceleration sensor is attached based on the output value of the acceleration sensor, the recognized inclination amount of the axis of the acceleration sensor, and the acquired longitudinal acceleration and lateral acceleration; Vertical acceleration detection method including

  As described above, the vertical acceleration sensor cannot accurately detect the vertical acceleration, which is the planned detection direction, unless it is attached to the vehicle body so that its sensor axis line and the vertical axis line coincide with each other. Further, while the vehicle is running, longitudinal acceleration caused by acceleration / deceleration of the vehicle and lateral acceleration caused by turning of the vehicle also occur. Therefore, when the axis of the vertical acceleration sensor is tilted, these longitudinal acceleration, lateral acceleration are generated. This also affects the detection value of the vertical acceleration sensor. According to the vertical acceleration detection method of this aspect, even if the axis of the vertical acceleration sensor is inclined, if the amount of inclination is known, the amount of inclination, longitudinal acceleration, and vertical acceleration can be used. It becomes possible to accurately detect the vertical acceleration.

  Note that “recognizing the amount of inclination of the axis of the acceleration sensor” referred to in this section is not a narrow concept of measuring the amount of inclination of the sensor axis, but is interpreted broadly. That is, it is a concept that includes making the amount of inclination of the sensor axis that has already been measured available in the calculation of vertical acceleration. In addition, “acquisition of longitudinal acceleration and lateral acceleration” referred to in this section means, for example, detection using a longitudinal acceleration sensor, lateral acceleration sensor, etc., detection of parameters capable of estimating longitudinal acceleration and lateral acceleration, It means that the longitudinal acceleration and lateral acceleration are estimated based on the parameters.

  The specific method for calculating the vertical acceleration in the aspect of this section is not particularly limited. For example, when vertical acceleration is generated at a part of the vehicle body to which the vertical acceleration sensor is attached, longitudinal acceleration and lateral acceleration are generated at the vehicle body, and the acceleration sensor is tilted, the direction in which the axis of the acceleration sensor extends ( Hereinafter, a combination of acceleration components (hereinafter sometimes referred to as “sensor axial direction components”) in “sensor axial direction”) is a detection value of the acceleration sensor. In view of this, the sensor axis direction component of longitudinal acceleration and lateral acceleration generated by tilting the sensor axis is subtracted from the output value of the vertical acceleration sensor, and the value after the subtraction is corrected based on the amount of tilt of the sensor axis. This method can be adopted.

(6) The upper limit acceleration detecting method further includes a step of acquiring a pitch amount and a roll amount of the vehicle body,
The step of calculating the vertical acceleration further calculates the vertical acceleration at the site where the acceleration sensor is attached based on the acquired pitch amount and roll amount of the vehicle body. Acceleration detection method.

  While the vehicle is running, the vehicle body pitches and rolls. If the vehicle body pitches and rolls, the detection value of the vertical acceleration sensor is affected by the inclination of the sensor axis of the acceleration sensor due to the pitch and roll. According to the aspect of this section, since the vertical acceleration is calculated further taking into account the pitch amount and roll amount of the vehicle body, the vertical acceleration can be detected more accurately.

  The specific method for calculating the vertical acceleration in the aspect of this section is not particularly limited. For example, based on the sensor axis direction component of the longitudinal acceleration obtained from the output value of the vertical acceleration sensor based on the tilt amount of the sensor axis and the pitch amount of the vehicle body, and on the basis of the tilt amount of the sensor axis line and the roll amount of the vehicle body A method of subtracting the obtained lateral acceleration component from the sensor axis direction and correcting the subtracted value based on the tilt amount, pitch amount, and roll amount of the sensor axis line can be employed.

(7) A method for detecting vertical acceleration in each of the three or more parts by means of three or more acceleration sensors that are attached to the vehicle body at three or more parts and that detect acceleration in the direction of the axis,
Recognizing the amount of inclination of each axis of the three or more acceleration sensors;
Obtaining the pitch amount and roll amount of the vehicle body;
Based on the output value of each of the three or more acceleration sensors, the recognized amount of inclination of the axis of each of the three or more acceleration sensors, and the acquired pitch amount and roll amount of the vehicle body, Calculating the vertical acceleration in at least one part of the parts.

  The aspect of this section is a method for detecting the vertical acceleration at any one of the three or more parts when the vertical acceleration sensor is attached to each of the three or more parts of the vehicle body. Even if each acceleration sensor is tilted, if the amount of tilt is known, the top and bottom of the body part to which one of the sensors is attached is based on the tilt amount, the pitch amount of the vehicle body, and the roll amount. The acceleration can be accurately detected. Although the specific aspect of the method for calculating the vertical acceleration in the aspect of this section is not particularly limited, for example, the following method can be employed.

  In the vehicle body, there is an acceleration (hereinafter sometimes referred to as “translational motion acceleration”) that attempts to translate it. The components of the translational acceleration in the front-rear direction, the left-right direction, and the up-down direction have the same magnitude at any position regardless of the position of the body part. On the other hand, in each part of the vehicle body, in the case of pitch and roll, acceleration depending on the pitch and force to be rolled (hereinafter sometimes referred to as “pitch / roll dependent acceleration”) occurs. Each component of the acceleration in the longitudinal direction, the lateral direction, and the vertical direction has a magnitude depending on the position of the body part. That is, the translational acceleration and the pitch / roll-dependent acceleration are generated in the part where the vertical acceleration sensor is attached, and the sum of the respective vertical components is detected by the acceleration sensor. It can be considered as a vertical acceleration.

  Based on the above considerations, first, the acquired pitch amount and roll amount, and more specifically, the components in the front-rear direction, left-right direction, and up-down direction of the pitch / roll-dependent acceleration based on changes in the pitch amount and roll amount. Is calculated for each part to which each of the three or more vertical acceleration sensors is attached. Next, the longitudinal component, the lateral component, and the vertical component of the translational motion acceleration are set as variables (unknown numbers), and the sensor axis of each component of the translational motion acceleration and the calculated pitch / roll-dependent acceleration component Three or more equations that the direction component, that is, the sum of the sensor axis direction components derived from the tilt amount, the pitch amount of the vehicle body, and the roll amount from each component is equal to the output value of the vertical acceleration sensor For each vertical acceleration sensor. Then, by solving the three or more equations as simultaneous equations, the vertical component of the translational motion acceleration, which is one of the unknowns, is obtained, and the vertical component of the obtained translational motion acceleration is determined for each part first. By adding up and down components of the calculated pitch / roll-dependent acceleration, the vertical acceleration to be detected at one or more of the parts is calculated. With such a method, the vertical acceleration can be accurately calculated.

  Note that “recognizing the amount of inclination of the axis of the acceleration sensor” referred to in this section is not a narrow concept of measuring the amount of inclination of the sensor axis, as in the previous aspect, but is interpreted broadly. That is, it is a concept that includes making the amount of inclination of the sensor axis that has already been measured available in the calculation of vertical acceleration. Moreover, “acquiring the pitch amount and roll amount of the vehicle body” referred to in this section means, for example, detecting the pitch amount and roll amount using a vehicle inclinometer or the like, the distance between vehicle body wheels for each wheel, etc. This means that a parameter capable of estimating the pitch amount and roll amount is detected, and the pitch amount and roll amount are estimated based on the parameters.

(8) The step of calculating the vertical acceleration includes:
Based on the output value of each of the three or more acceleration sensors, the recognized amount of inclination of the axis of each of the three or more acceleration sensors, and the acquired pitch amount and roll amount of the vehicle body, The method for detecting vertical acceleration according to item (7), which is a step of calculating at least one of longitudinal acceleration and lateral acceleration of the vehicle body along with vertical acceleration at at least one of the regions.

  In this mode, the longitudinal acceleration and lateral acceleration of the vehicle body are also detected using the fact that the axis of the vertical acceleration sensor is inclined. By grasping the amount of inclination of the axis of each vertical acceleration sensor, the longitudinal acceleration and lateral acceleration of the vehicle body can be detected even in a vehicle that does not include the longitudinal acceleration sensor and lateral acceleration sensor according to the aspect of this section. Is possible.

  In the aspect of this section, the specific aspect of the method for calculating the longitudinal acceleration and the lateral acceleration is not particularly limited. For example, when adopting the above-described specific calculation method of vertical acceleration, that is, the calculation method based on translational acceleration and pitch / roll-dependent acceleration, the longitudinal direction of the translational acceleration described above set as an unknown number Since the component and the lateral component correspond to the longitudinal acceleration and lateral acceleration of the vehicle body, respectively, the longitudinal acceleration and lateral acceleration can be calculated by solving the above three or more simultaneous equations.

  Hereinafter, an example in which the claimable invention is applied to a specific vehicle suspension system will be described in detail as an embodiment of the claimable invention with reference to the drawings. In addition to the following embodiments, the claimable invention should be implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Modes of Invention]. Can do.

≪Configuration of vehicle suspension system≫
FIG. 1 schematically shows a vehicle suspension system 10 to which the claimable invention is applied. The suspension system 10 includes four independent suspension type suspension devices corresponding to the front, rear, left, and right wheels 12, each of which is a spring in which a suspension spring and a shock absorber are integrated.・ Has an absorber assembly 20. The wheel 12 and the spring absorber assembly 20 are generic names, and when it is necessary to clarify which of the four wheels corresponds, as shown in FIG. In some cases, FL, FR, RL, and RR are attached to the front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  As shown in FIG. 2, the spring absorber assembly 20 is arranged between a suspension lower arm 22 as a wheel holding member for holding the wheel 12 and a mount portion 24 provided on the vehicle body so as to connect them. And an electromagnetic actuator 26 functioning as an electromagnetic shock absorber, and a coil spring 28 as a suspension spring provided in parallel therewith. The actuator 26, which will be described in detail later, functions as an approaching / separating force generating device because the wheel 12 and the vehicle body can be approached / separated by a force generated by itself.

  The actuator 26 includes an outer tube 30 and an inner tube 32 that fits into the outer tube 30 and protrudes upward from the upper end portion of the outer tube 30. The outer tube 30 is connected to the lower arm 22 via a mounting member 34 provided at the lower end portion thereof, while the inner tube 32 is connected to the mount portion 24 at a flange portion 36 formed at the upper end portion thereof. ing. The outer tube 30 is provided with a pair of guide grooves 38 on the inner wall surface thereof so as to extend in the direction in which the axis of the actuator 26 extends (hereinafter sometimes referred to as “actuator axial direction”). Each of a pair of keys 40 attached to the lower end of the inner tube 32 is fitted in each of the inner tubes 32, and the outer tube 30 and the inner tube 32 are connected by the guide grooves 38 and the keys 40. The relative rotation is impossible and the relative movement is possible in the axial direction.

  The actuator 26 also includes a ball screw mechanism including a screw rod 50 having a thread groove, a nut 52 that holds the bearing ball and is screwed with the screw rod 50, and an electromagnetic motor 54 (3 Phase DC brushless motor, hereinafter simply referred to as "motor 54"). The motor 54 is fixedly accommodated in the motor case 56, and the flange portion of the motor case 56 is fixed to the upper surface side of the mount portion 24, and the flange portion 36 of the inner tube 32 is attached to the flange portion of the motor case 56. By being fixed, the inner tube 32 is connected to the mount portion 24 via the motor case 56. A motor shaft 58 that is a rotation shaft of the motor 54 is integrally connected to the upper end portion of the screw rod 50. That is, the screw rod 50 is disposed in the inner tube 32 with the motor shaft 58 extended, and is rotated by the motor 54. On the other hand, the nut 52 is fixedly supported by the upper end portion of the nut support cylinder 60 attached to the inner bottom portion of the outer tube 30 in a state where the nut 52 is screwed with the screw rod 50. The outer tube 30 is provided with an annular lower retainer 62 on the outer peripheral portion thereof, and the coil spring 28 is interposed between the lower retainer 62 and a vibration isolating rubber 64 attached to the lower surface side of the mount portion 24. It is arrange | positioned in the state pinched | interposed by the cyclic | annular upper retainer 66 provided in this way.

  When the vehicle body and the wheel 12 approach and separate from each other, the outer tube 30 and the inner tube 32 move relative to each other in the actuator axial direction. Along with the relative movement, the screw rod 50 and the nut 52 relatively move in the axial direction, and the screw rod 50 rotates with respect to the nut 52. The motor 54 can apply a rotational torque to the screw rod 50, and the rotational torque can generate a resistance force in a direction that prevents the approach and separation between the vehicle body and the wheel 12. It is possible. This resistance force becomes a damping force that attenuates vibrations of the wheel 12 and the vehicle body in the approaching / separating directions thereof, so that the actuator 26 functions as a shock absorber. In other words, the actuator 26 can cause an actuator force, which is a force generated by the actuator 26, to act as a damping force. The actuator 26 also has a function of moving the vehicle body and the wheel 12 closer to or away from each other by the actuator force. With this function, it is possible to effectively suppress the posture change of the vehicle body due to the roll of the vehicle body when turning the vehicle, the pitch of the vehicle body when the vehicle is accelerated or decelerated, and the like. That is, the actuator force can be exhibited as a posture control force that is a force for controlling the posture of the vehicle body.

  As shown in FIG. 1, the suspension system 10 is provided with an actuator electronic control unit (ECU) 80 as a control device for controlling the operation of the actuator 26, that is, the actuator force. The ECU 80 is a controller 82 (represented as “CONT” in FIG. 1) composed mainly of a computer having a CPU, ROM, RAM, and the like, and a drive circuit for the motor 54 included in each actuator 26. There are four inverters 84 (indicated as “INV” in FIG. 1). Each motor 54 is connected to a battery 86 (represented as “BAT” in FIG. 1) as a power source via a corresponding inverter 84. Further, the controller 82 is connected to each inverter 84, and each actuator 84 controls the energization current of the motor 54 according to the command of the controller 82, so that each actuator 26 has a magnitude corresponding to the energization current of the motor 54. The actuator force is generated.

  The controller 82 includes a vehicle speed sensor 88 for detecting a vehicle traveling speed (hereinafter sometimes abbreviated as “vehicle speed”), an operation angle sensor 90 for detecting an operation angle of the steering wheel, and actually generated in the vehicle body. A lateral acceleration sensor 92 for detecting an actual lateral acceleration, which is a lateral acceleration, four vertical acceleration sensors 94 for detecting vertical acceleration (spring top vertical acceleration) of each mount 24 of the vehicle body corresponding to each wheel 12, A longitudinal acceleration sensor 98 for detecting the actual longitudinal acceleration, which is the longitudinal acceleration actually generated in the vehicle body, and four stroke sensors 100 for measuring the distance between the wheel and the vehicle body in each spring absorber assembly 20 are also connected. Yes. (In FIG. 1, they are represented as “v”, “δ”, “Gy”, “Gz”, “Gx”, and “St”, respectively). Further, a sensor inclination amount side processing start switch 102 (shown as “Sw” in FIG. 1) operated by the driver is provided in the passenger compartment, and this switch 102 is also connected to the controller 82. ing. Note that the ROM included in the computer of the controller 82 stores an actuator control program, a vertical acceleration sensor axis inclination measurement program, various data, and the like, which will be described later.

≪Control of suspension system≫
In the present suspension system 10, the four actuators 26 can be controlled independently. That is, the actuator force is controlled independently to control the vibration of the wheel and the vehicle body (hereinafter, also referred to as “vibration damping control”), the control to suppress the roll of the vehicle body (hereinafter “roll suppression”). Control) (hereinafter sometimes referred to as “pitch suppression control”). The vibration damping control, roll suppression control, and pitch suppression control are executed by causing the actuator force to act as a damping force, a roll suppression force, and a pitch suppression force, respectively. Specifically, the target actuator force is determined by summing the damping actuator force component, the roll suppression actuator force component, and the pitch suppression actuator force component, which are actuator forces for each control of vibration damping control, roll suppression control, and pitch suppression control. The actuator 26 is normally executed in a unified manner by being controlled so as to exert its target actuator force. Hereinafter, each of vibration damping control, roll suppression control, and pitch suppression control will be described in detail focusing on a method for determining an actuator force component in each of them, and operation control of the motor 54 for controlling the actuator force will be described in detail. To do.

i) the vibration damping control vibration damping control, in order to exert the actuator force having a magnitude corresponding to the speed of vibration of the wheel and the vehicle body, the damping actuator force component F _G is determined to damp vibrations of the wheel and the vehicle body . Vertical operating speed of the vehicle body mounting portion 24, so-called sprung speed (sprung absolute speed) based on V _U, according to the following equation, the damping actuator force component F _G is calculated.
F _G = C _U · V _U
Here, _CU is a gain for exerting a damping force according to the vertical movement speed of the mount 24 of the vehicle body, that is, a so-called damping coefficient. As can be seen from the above equation, the vibration damping control is performed based on the skyhook damper theory. The sprung speed V _U is calculated based on the sprung vertical acceleration G _z detected based on the output value of the vertical acceleration sensor 94. The detection of the sprung vertical acceleration _Gz will be described later.

ii) Roll suppression control In roll suppression control, when the vehicle turns, the actuator force in the bounce direction is applied to the actuator 26 on the inner ring side and the actuator 26 on the outer ring side in the rebound direction according to the roll moment resulting from the turn. The actuator force is exhibited as a roll restraining force. Specifically, first, as a lateral acceleration indexing the roll moment received by the vehicle body, an actual lateral acceleration G _yc estimated based on the steering angle δ of the steering wheel and the vehicle traveling speed v is actually generated. Based on the actual lateral acceleration G _yr which is the lateral acceleration of the vehicle body, a control lateral acceleration G _y ^* which is a lateral acceleration used for control is determined according to the following equation:
G _y ^* = K _A · G _yc + K _B · G _yr (K _A and K _B are gains)
Such based on the determined control-use lateral acceleration G _y ^*, the roll restraining actuator force component F _R is determined. The in the controller 82 are stored map data for controlling the lateral acceleration G _y ^* is referred to as parameter roll restraining actuator force component F _R is, by referring to the map data, roll restraining actuator force component F _R is determined . The actual lateral acceleration G _yr may be detected based on the output value of the lateral acceleration sensor 92. As will be described later, the output value of the vertical acceleration sensor 94, the sensor axis line of the sensor, and the like. You may detect by calculating based on the amount of inclinations, the acquired pitch amount, and roll amount.

iii) Pitch suppression control In the pitch suppression control, for the nose dive of the vehicle body that occurs during braking of the vehicle body, the actuator 26FL, FR on the front wheel side in the rebound direction depends on the pitch moment that causes the nose dive. Actuating the actuator force in the bounce direction to the rear wheel side actuators 26RL and RR as the pitch restraining force, the nose dive is restrained, and against the squat of the vehicle body generated during acceleration of the vehicle body, etc. In response to the pitch moment causing the squat, the actuator 26RL, RR on the rear wheel side exerts the actuator force in the rebound direction, and the actuator force on the front wheel side 26FL, FR uses the actuator force in the bound direction as a pitch suppression force. So that squat is suppressed Is done. Specifically, an actual longitudinal acceleration G _x which is an actual longitudinal acceleration of the vehicle body is adopted as the longitudinal acceleration indicating the pitch moment received by the vehicle body, and the pitch suppression actuator force is based on the actual longitudinal acceleration G _x. The component _FP is determined according to the following equation:
F _P = K _C · G _x (K _C is the gain)
The actual longitudinal acceleration _Gx may be detected based on the output value of the longitudinal acceleration sensor 98. As will be described later, the output value of the vertical acceleration sensor 94, the sensor axis line of the sensor, and the like. You may detect by calculating based on the amount of inclinations, the acquired pitch amount, and roll amount.

iv) Actuator force and motor operation control As described above, when the damping actuator force component F _G , the roll suppression actuator force component F _R , and the pitch suppression actuator force component _FP are determined, the target actuator force F _A is calculated according to the following equation. Determined,
F _A = F _G + F _R + F _P
Actuator 26 is controlled so as to exert a determined target actuator force F _A. The operation control of the motor 54 for exerting the target actuator force F _A is performed by the inverter 84. More specifically, a command for the energization current of the motor 54 for generating the determined target actuator force F _A is issued to the inverter 84.

v) Actuator control program As described above, the actuator 26 is controlled by the actuator control program shown in the flowchart of FIG. 3 at a short time interval (for example, several milliseconds) while the ignition switch is in the ON state. This is performed by being repeatedly executed by 82. The control flow will be briefly described below with reference to the flowchart shown in the figure.

  The actuator control program is executed for each actuator 26 of the spring absorber assembly 20 provided on each of the four wheels 12. In the following description, the processing by this program for one actuator 26 will be described in consideration of the simplification of the description. However, when it is necessary to clarify which actuator the processing is for. In some cases, a subscript indicating a wheel position is attached.

In the processing according to this program, first, in step 1 (hereinafter, simply referred to as “S1”, the same applies to other steps), the estimated lateral direction described above is based on the steering angle δ of the steering wheel and the vehicle traveling speed v. The acceleration G _yc is estimated. Next, in S2, the above-described sprung vertical acceleration G _z , actual lateral acceleration G _yr , and actual longitudinal acceleration G _x are detected. These accelerations are detected by executing an acceleration detection subroutine. A method and a specific process regarding detection of each acceleration will be described in detail later.

Next, in order to execute the vibration damping control described above, in S3, based on the vertical acceleration G _z springs detected in S2, sprung speed V _U is calculated, in S4, based on the sprung speed V _U the damping actuator force component F _G is determined Te. Subsequently, in order to execute roll suppression control, in S5, the control lateral acceleration _Gy ^* is calculated based on the estimated lateral acceleration _Gyc estimated in S1 and the actual lateral acceleration _Gyr detected in S2. It is, in S6, on the basis of the calculated control lateral acceleration G _y ^*, the roll restraining actuator force component F _R is determined. Furthermore, in order to perform the pitch restrain control, in S7, on the basis of the actual longitudinal acceleration G _x detected by S2, the pitch reduction actuator force component F _P is determined.

Subsequently, in S8, is damping actuator force component F _G, roll restraining actuator force is determined in S6 component F _R, S7 pitch restrain actuator force component F _P determined in the summed determined S4, the target The actuator force F _A is determined. After the target actuator force F _A is determined, a control signal corresponding to the determined target actuator force F _A is sent to the inverter 84 in S9, and the motor 54 is controlled by the inverter 84. Through these processes, the actuator 26 is controlled to generate the determined target actuator force F _A.

≪Effect of vertical acceleration sensor structure and axis inclination≫
The vertical acceleration sensor 94 used in the present system has an appearance as shown in FIG. 4, and is attached to the vehicle body corresponding to the four front, rear, left and right wheels. The internal structure of the vertical acceleration sensor 94 is schematically shown in FIG. Specifically, the vertical acceleration sensor 94 includes a case body 114 in which a box-shaped upper case 110 having an open lower end and a box-shaped lower case 112 having an open upper end are combined. The case 110 and the lower case 112 can be expanded and contracted by being relatively movable in the vertical direction in the figure. A weight 116 is fixed to the bottom of the lower case 112, and the upper case 110 includes a pair of electrodes 118 and a piezoelectric element 120 sandwiched between them on the ceiling. A piezoelectric element unit 122 is fixed. Inside the case body 114, a pair of tension coil springs 124 are arranged in a state of exerting an elastic force in a direction in which the case body 114 contracts in the vertical direction. 116 is pressed against the piezoelectric element unit 122. The vertical acceleration sensor 94 is attached to the vehicle body with a pair of brackets 126 provided on the upper case 110.

  With such a structure, when the vertical acceleration sensor 94 generates vertical acceleration, the force by which the weight 116 presses the piezoelectric element unit 122 changes according to the magnitude of the acceleration. Due to the change, the deformation of the piezoelectric element 120 changes, and a voltage corresponding to the change is generated between the pair of electrodes 118. This voltage is the output value of the vertical acceleration sensor 94, and the vertical acceleration can be detected based on the voltage. Incidentally, when the vehicle is stationary, the vertical acceleration sensor outputs an output value corresponding to the gravitational acceleration, and the acceleration excluding the gravitational acceleration becomes the vertical acceleration generated depending on the movement of the vehicle body. .

  5 is the axis of the vertical acceleration sensor 94, that is, the sensor axis SL, and extends in the vertical direction of the drawing. The direction in which the sensor axis SL extends is the sensor axis direction, and the vertical acceleration sensor 94 outputs the acceleration in this direction as an output value. However, the vertical acceleration sensor 94 is not necessarily attached in the correct orientation with respect to the vehicle body, and it is inevitable that an attachment error occurs.

For example, as shown in FIG. 4, it is assumed that the vertical acceleration sensor 94 is tilted and attached. The vector shown in the figure is a sensor axis direction vector S indicating the direction in which the sensor axis extends. Here, in order to define the amount of inclination of the vertical acceleration sensor 94, three axes orthogonal to each other, the x axis, the y axis, and the z axis shown in the figure, are defined. By the way, the axes of those axes are axes extending in the front-rear direction, the left-right direction, and the up-down direction of the vehicle, respectively, in the standard state where the vehicle is stationary on a horizontal plane. These are called the axis and vertical axis. In the following description, the amount of inclination of the vertical acceleration sensor 94 is considered based on the x-axis, y-axis, and z-axis, and the angle formed by the sensor direction vector S with respect to each axis, that is, the front-rear axis angle ρ _x , The horizontal axis angle ρ _y , and the vertical axis angle ρ _z .

  The vertical acceleration sensor 94 is a sensor whose purpose is to detect vertical acceleration, in other words, a sensor whose scheduled detection direction is the vertical direction. However, when the sensor axis SL is inclined as shown in FIG. 4, the vertical acceleration sensor 94 does not accurately output the vertical acceleration. More specifically, even when a certain amount of acceleration occurs in the vertical direction, only a component along the sensor axis direction, that is, an output value corresponding to the sensor axis direction component is output. When acceleration occurs in the front-rear direction and the left-right direction, an output having a magnitude corresponding to the sensor axial direction component of the acceleration is output. In such a case, the vibration damping control based on the output value of the vertical acceleration sensor 94 is not appropriately performed.

  When the vehicle body is pitched, the vehicle body rotates about the y-axis, so that the x-axis and the z-axis itself are inclined. When the vehicle body rolls, the vehicle body rotates about the x-axis, so that y The axis and the z axis itself are inclined. In these cases, the sensor axis SL of the vertical acceleration sensor 94 is also inclined, and similarly, an accurate output cannot be obtained for the vertical acceleration. That is, the output value of the vertical acceleration sensor 94 is not only influenced by the inclination of the sensor axis SL with respect to the axis of the vehicle body, but also influenced by the pitch and roll of the vehicle body.

Incidentally, in the following description, as shown in FIG. 4, the pitch amount is the pitch angle θ _p that is the inclination angle of the x-axis with respect to the horizontal plane, and the roll amount is the roll angle θ _r that is the inclination angle of the y-axis with respect to the horizontal plane. Shall be defined respectively.

≪Measurement of vertical inclination of vertical acceleration sensor≫
In the vehicle suspension system 10, the vertical acceleration sensor 94 measures the tilt amount of the vertical acceleration sensor 94 in order to accurately detect the vertical acceleration. The method will be described below.

一方、対前後軸線角ρ_x，対横軸線角ρ_y，対上下軸線角ρ_zは、三平方の定理から、下記式（２）の関係が成立する。

したがって、ピッチ量とロール量との両方において互いに異なる２つの姿勢、つまり、第１姿勢と第２姿勢とのそれぞれについての上記式（１）と、上記式（２）とからなる３つの連立方程式を解けば、対前後軸線角ρ_x，対横軸線角ρ_y，対上下軸線角ρ_zを算出することができるのである。なお、上下加速度センサが上下逆さに取り付けられるような場合はないと考え、対前後軸線角ρ_x，対横軸線角ρ_y，対上下軸線角ρ_zは、それぞれ、０≦ρ_x、ρ_y≦π、０≦ρ_z≦π／２となることを前提として、連立方程式を解けばよい。 When the vehicle is in a stopped state, it can be considered that only gravity acts on the part of the vehicle body to which the vertical acceleration sensor 94 is attached. In that case, the output value G _s of the vertical acceleration sensor 94 (hereinafter, the output value is treated as an acceleration converted) should be the gravitational acceleration g. However, the sensor axis SL of the vertical acceleration sensor 94 is inclined with respect to the three axes of the vehicle body by the longitudinal axis angle ρ _x , the lateral axis angle ρ _y , and the vertical axis angle ρ _z , and the vehicle body is When the posture is inclined so as to be the pitch angle θ _p and the roll angle θ _r , the relationship between the output value G _s and the gravitational acceleration g is expressed by the following equation (1).

On the other hand, the relationship of the following formula (2) holds between the front-rear axis angle ρ _x , the horizontal axis angle ρ _y , and the upper-lower axis angle ρ _z from the three-square theorem.

Therefore, three simultaneous equations comprising the above formula (1) and the above formula (2) for two different postures in both the pitch amount and the roll amount, that is, the first posture and the second posture, respectively. , It is possible to calculate the longitudinal axis angle ρ _x , the lateral axis angle ρ _y , and the vertical axis angle ρ _z . In addition, it is considered that the vertical acceleration sensor is not mounted upside down, and the vertical axis angle ρ _x , the horizontal axis angle ρ _y , and the vertical axis angle ρ _z are 0 ≦ ρ _x and ρ _y , respectively. Assuming that ≦ π and 0 ≦ ρ _z ≦ π / 2, the simultaneous equations may be solved.

When the vehicle body is in a posture with only a pitch, since the roll angle θ _r is 0, the above equation (1) is expressed by the following equation (3), and the vehicle body is only a roll. When the posture is such that the above equation (1) can be simplified as the following equation (4).

  Under such an idea, in the present suspension system 10, from the vehicle body posture when the vehicle is in the standard state, that is, the posture not inclined (hereinafter sometimes referred to as “horizontal posture”), first, FIG. As shown in a), the first posture is a posture in which the vehicle body has only a pitch. In this first posture, the actuator force in the same direction is generated in the two actuators 26 on the front wheel side from the horizontal posture, and the two actuators 26 on the rear wheel side are opposite to the actuator 26 on the front wheel side. This is achieved by generating an actuator force in the direction. By the way, in the figure, the vehicle body is pitched so that the front wheel side bounces and the rear wheel side rebounds.

With the first posture maintained, the output value G _s of each vertical acceleration sensor 94, that is, the first sensor output value G _s1 is acquired. At the same time, from the average of the output values of the two stroke sensors 100 on the front wheel side, the front wheel side displacement amount _Stfr , which is the displacement amount in the vertical direction on the vehicle body front wheel side from the horizontal posture, is obtained. From the difference from the average of the output values of the two stroke sensors 100, the rear wheel side displacement amount S _tre which is the displacement amount in the vertical direction on the vehicle body rear wheel side from the standard state is obtained. And based on the wheelbase L grasped | ascertained previously, it calculates based on following formula (5), and acquires the pitch angle (theta) _p of a vehicle body.

  Next, from the first posture, as shown in FIG. 6B, the second posture is a posture in which the vehicle body only rolls. In this second posture, two right wheel side actuators 26 generate actuator forces in the same direction, and two left wheel side actuators 26 are actuators in opposite directions to the right wheel side actuators 26. Realized by generating force. By the way, in the figure, the vehicle body is rolled such that the right wheel side bounces and the left wheel side rebounds.

In a state where the second posture is maintained, the output value G _s of each vertical acceleration sensor 94, that is, the second sensor output value G _s2 is acquired. At the same time, from the average of the output values of the two right wheel side stroke sensors 100, the right wheel side displacement amount S _tri , which is the vertical displacement amount on the right side of the vehicle body from the standard state, is obtained. From the difference between the average output values of the two stroke sensors 100, a left wheel side displacement amount S _tle that is a displacement amount in the vertical direction on the vehicle body left wheel side from the standard state is acquired. And based on the tread T grasped | ascertained previously, it calculates based on following formula (6), and acquires roll angle (theta) _r of a vehicle body.

Based on the first sensor output value G _s1 and the pitch angle θ _p acquired as described above, the first equation according to the above equation (3) is established, and the second sensor output value G _s2 and the roll angle θ _r are obtained. Based on the above equation (4), the second equation is established, and the simultaneous equations of the two equations and the above equation (2) are solved, so that the vertical axis angle ρ _x , The axis angle ρ _y and the vertical axis angle ρ _z are calculated. In this way, the amount of inclination of the sensor axis SL of each vertical acceleration sensor 94 is measured.

In the present system 10, as described above, the inclination amount of the sensor axis SL of each vertical acceleration sensor 94 is measured. For example, the first posture and the second posture are each applied to the vehicle body a plurality of times. The amount of inclination of the sensor axis SL of each vertical acceleration sensor 94 may be measured by obtaining the output value G _s of each vertical acceleration sensor 94 each time and averaging them. Further, one or more postures different in pitch amount and roll amount from the first posture and the second posture are further taken, and an output value G _s of each vertical acceleration sensor 94 is obtained for each posture, and each vertical acceleration is obtained. The amount of inclination of the sensor axis SL of the sensor 94 may be measured. Thus, if the number of acquisitions of the output value G _s of each vertical acceleration sensor 94 is increased, more accurate measurement can be performed. Further, the first posture and the second posture are postures in which only the pitch and only the roll are used, respectively, but may be postures in which the pitch and the roll are also used.

  In the system 10, the above-described measurement of the vertical acceleration sensor axis inclination amount is triggered by the operation of the sensor inclination amount side processing start switch 102 by the driver, and the controller 82 uses the sensor axis inclination amount measurement program whose flowchart is shown in FIG. Is done by running Hereinafter, processing according to this program will be described.

First, in S21, while monitoring the output values of the four stroke sensors 100, the actuator forces of the four actuators 26 are controlled to bring the vehicle body into a horizontal posture. Next, in S22, by applying a predetermined actuator force to the four actuators 26, the vehicle body is set to the first posture. After the first posture is realized, the pitch angle θ _p is acquired as described above in S23, and in S24, the output value G _s of each vertical acceleration sensor 94 is set as the first sensor output value G _s1. get. Next, in S25, after returning the vehicle body to a horizontal posture, a predetermined actuator force is applied to the four actuators 26, whereby the vehicle body is set to the second posture. After the second attitude is realized, the roll angle θ _r is acquired as described above in S26, and in S27, the output value G _s of each vertical acceleration sensor 94 is set as the second sensor output value G _s2. get. Thereafter, in S28, based on the acquired pitch angle θ _p , roll angle θ _r , first sensor output value G _s1 , second sensor output value G _s2 , the front-rear axis angle ρ _x , The axis angle ρ _y and the vertical axis angle ρ _z are calculated. After the calculation, in S29, the longitudinal axis angle ρ _x , the lateral axis angle ρ _y , and the vertical axis angle ρ _z obtained by measurement are stored in a storage area such as a ROM or RAM of the controller 82. In S30, the actuator force of each actuator 26 is released, and the processing according to this program ends.

  Note that the processing by the execution of the sensor axis inclination amount measurement program is the first in which the processing in S22 and S24 takes the vehicle body as the first posture and acquires the first sensor output value that is the output value of the acceleration sensor in that posture. This corresponds to a sensor output value acquisition step, and the processing in S25 and S27 sets the vehicle body to a second posture that is different from the first posture in the pitch amount and the roll amount, and the second output value that is the output value of the acceleration sensor in that posture. This corresponds to a second sensor output value acquisition step of acquiring a sensor output value, and the processing in S28 includes the first sensor output value and the second sensor output value, and the roll amount and pitch amount in each of the first posture and the second posture. This corresponds to a sensor tilt amount calculation step of calculating the tilt amount of the axis of the acceleration sensor.

≪Detection of sprung vertical acceleration based on tilt amount≫
As described above, in the control of the actuator 26, the sprung vertical acceleration G _z , the actual lateral acceleration G _yr , and the actual longitudinal acceleration G _x are detected, and the actuator force is determined based on them. In the vehicle suspension system 10, the sprung vertical acceleration G _z is calculated based on the output value of the vertical acceleration sensor 94 and the tilt amount of the vertical acceleration sensor 94 measured as described above. As the calculation method, the following three methods can be employed. Below, the detection process based on each method is demonstrated. Since the detection of the sprung vertical acceleration G _z , the actual lateral acceleration G _yr , and the actual longitudinal acceleration G _x is performed in S2 of the actuator control program, the description of the acceleration detection subroutine constituting the S2 is also performed.

上記式に従う算出手法は、簡単に言えば、上下加速度センサ９４のセンサ軸線ＳＬが傾くことによって生じる実前後加速度Ｇ_xのセンサ軸線方向成分，実横加速度Ｇ_yrのセンサ軸線方向成分を、それぞれ、対前後軸線角ρ_x，対横軸線角ρ_yに基づいて認定し、その認定された各センサ軸線方向成分を、上下加速度センサ９４の出力値Ｇ_sから差し引き、その差し引いた後の値を、対上下軸線角ρ_zに基づいて補正するというものである。 i) Vertical acceleration detection processing 1 based on the tilt amount of the sensor axis
In the present detection process, the sprung vertical acceleration G _z (hereinafter sometimes simply referred to as “vertical acceleration G _z ”) is calculated using the acquired actual lateral acceleration G _yr and actual longitudinal acceleration G _x. . Specifically, the vertical acceleration G _{z of the} part to which each vertical acceleration sensor 94 is attached is calculated according to the following formula (7) when the output value of each vertical acceleration sensor 94 is G _s .

In short, the calculation method according to the above equation is obtained by calculating the sensor axial direction component of the actual longitudinal acceleration G _{x and} the sensor axial direction component of the actual lateral acceleration G _yr caused by the inclination of the sensor axis SL of the vertical acceleration sensor 94, respectively. Based on the front-rear axis angle ρ _x and the horizontal axis angle ρ _y , the sensor axial direction component is subtracted from the output value G _s of the vertical acceleration sensor 94, and the subtracted value is is that corrected based on the pair vertical axis angle [rho _z.

This detection process is performed by executing a first acceleration detection subroutine whose flowchart is shown in FIG. In the process according to this subroutine, first, in S41, it is recognized by the pair of front and rear axial angle [rho _x, vs. transverse axis angle [rho _y, versus the vertical axis angle [rho _z is the value stored in the storage area described above is read The Next, in S42, the actual longitudinal acceleration _Gx is acquired based on the output value of the longitudinal acceleration sensor 98, and in S43, the actual lateral acceleration _Gyr is acquired based on the output value of the lateral acceleration sensor 92. Subsequently, in S44, the output value G _s of the vertical acceleration sensor 94 is acquired. In S45, the recognized longitudinal axis angle ρ _x , the transverse axis angle ρ _y , the vertically axis angle ρ _z , the obtained actual longitudinal acceleration G _x , the actual lateral acceleration G _yr , the obtained vertical acceleration sensor on the basis of the output value G _s of 94, according to the above formula, the vertical acceleration G _z sites attached the vertical acceleration sensor 94 is calculated. The process of S45 is executed, and the process according to the first acceleration detection subroutine ends.

上記式に従う算出手法は、簡単に言えば、上下加速度センサ９４のセンサ軸線ＳＬが傾くことによって生じる実前後加速度Ｇ_xのセンサ軸線方向成分，実横加速度Ｇ_yrのセンサ軸線方向成分を、それぞれ、対前後軸線角ρ_x，対横軸線角ρ_y，対上下軸線角ρ_z，ピッチ角θ_p，ロール角θ_rに基づいて認定し、その認定された各センサ軸線方向成分を、上下加速度センサ９４の出力値Ｇ_sから差し引き、その差し引いた後の値を、対前後軸線角ρ_x，対横軸線角ρ_y，対上下軸線角ρ_z，ピッチ角θ_p，ロール角θ_rに基づいて補正するというものである。式としては、複雑になるが、ピッチ角θ_p，ロール角θ_rの影響も加味して算出されるため、上下加速度Ｇ_zをより正確に検出することが可能である。 ii) Vertical acceleration detection process 2 based on the amount of inclination of the sensor axis
In this detection processing, the vertical acceleration G _z is calculated using the acquired actual lateral acceleration G _yr and actual longitudinal acceleration G _x , and further using the vehicle body pitch angle θ _p and roll angle θ _r. The Specifically, the vertical acceleration G _{z of the} part to which each vertical acceleration sensor 94 is attached is calculated according to the following formula (8) when the output value of each vertical acceleration sensor 94 is G _s .

In short, the calculation method according to the above equation is obtained by calculating the sensor axial direction component of the actual longitudinal acceleration G _{x and} the sensor axial direction component of the actual lateral acceleration G _yr caused by the inclination of the sensor axis SL of the vertical acceleration sensor 94, respectively. The vertical axis angle ρ _x , the horizontal axis angle ρ _y , the vertical axis angle ρ _z , the pitch angle θ _p , and the roll angle θ _r are certified, and each certified sensor axial direction component is identified as a vertical acceleration sensor. 94 is subtracted from the output value G _s and the subtracted value is based on the longitudinal axis angle ρ _x , the lateral axis angle ρ _y , the vertical axis angle ρ _z , the pitch angle θ _p , and the roll angle θ _r. It is to correct. Although the expression is complicated, it is calculated in consideration of the influence of the pitch angle θ _p and the roll angle θ _r , so that the vertical acceleration G _z can be detected more accurately.

The pitch angle θ _p is obtained by calculating according to the above equation (5) based on the front wheel side displacement amount S _tfr and the rear wheel side displacement amount S _tre described above. Further, the roll angle theta _r is the right wheel side displacement amount described above S _tri, based on the left wheel side displacement amount S _tle, is obtained by being calculated according to the equation (6).

This detection process is performed by executing the second acceleration detection subroutine shown in the flowchart of FIG. In the process according to this subroutine, first, in S51, it is recognized by the pair of front and rear axial angle [rho _x, vs. transverse axis angle [rho _y, versus the vertical axis angle [rho _z is the value stored in the storage area described above is read The Next, in S52, the actual longitudinal acceleration _Gx is acquired based on the output value of the longitudinal acceleration sensor 98, and in S53, the actual lateral acceleration _Gyr is acquired based on the output value of the lateral acceleration sensor 92. Further, in S54, the pitch angle θ _p is acquired based on the output values of the four stroke sensors 100, and in S55, the roll angle θ _r is acquired based on the output values of the four stroke sensors 100. Subsequently, in S56, the output value G _s of the vertical acceleration sensor 94 is acquired. In S57, the recognized longitudinal axis angle ρ _x , the transverse axis angle ρ _y , the vertically axis angle ρ _z , the obtained actual longitudinal acceleration G _x , the actual lateral acceleration G _yr , the pitch angle θ _p , the roll Based on the angle θ _r and the acquired output value G _s of the vertical acceleration sensor 94, the vertical acceleration G _{z of the} part to which the vertical acceleration sensor 94 is attached is calculated according to the above formula. The process of S57 is executed, and the process according to the second acceleration detection subroutine ends.

また、車体のピッチ，ロール動作時において、上下加速度センサ９４が取り付けられている車体の部位に生じている加速度は、上記式（９）を時間に関して２階微分することによって、下記式（１０）のようなベクトルの形式で表すことができる。ちなみに、「・・」は、時間に関する２階微分を行ったものを表している。

iii) Vertical acceleration detection processing 3 based on the tilt amount of the sensor axis
In the absolute space, the longitudinal axis of the vehicle is the X axis, the horizontal axis is the Y axis, the vertical axis is the Z axis, and the mounting position of the vertical acceleration sensor 94 in the absolute space when the vehicle is in a standard state is u ₀ = When (x ₀ , y ₀ , z ₀ ), when the vehicle body performs a pitch and roll operation by a pitch angle θ _p and a roll angle θ _r , the position of the vertical acceleration sensor 94 is u = (x, y, z). The u can be expressed by the following equation (9) using the transformation matrix R (θ _r , θ _p ). The X axis, Y axis, and Z axis coincide with the x axis, y axis, and z axis of the vehicle body described above when the vehicle is in a standard state. The values of x ₀ , y ₀ , and z ₀ are specifications relating to vehicle design and are known values.

In addition, the acceleration generated in the part of the vehicle body to which the vertical acceleration sensor 94 is attached during the pitch and roll operations of the vehicle body is expressed by the following equation (10) by differentiating the above equation (9) with respect to time. It can be expressed in the form of a vector such as By the way, “··” represents the result of second-order differentiation with respect to time.

なお、ピッチ角θ_p，ロール角θ_rは、上述のように、４つのストロークセンサ１００の出力値に基づいて取得することができ、また、それらピッチ角θ_p，ロール角θ_rは、短い時間間隔をおいて取得されるため、時間に関するそれらの１階微分値つまりピッチ角速度，ロール角速度、２階微分値つまりピッチ角加速度，ロール角加速度も、それらの変動の様子から取得することが可能である。したがって、上記式（１１），（１２），（１３）で示される加速度のＸ軸方向，Ｙ軸方向，Ｚ軸方向の成分は、算出することが可能である。 The components of the acceleration in the X-axis direction, Y-axis direction, and Z-axis direction shown in the above equation (10) can be expressed as the following equations (11), (12), and (13). Incidentally, “·” represents the result of first-order differentiation with respect to time.

Note that the pitch angle θ _p and the roll angle θ _r can be obtained based on the output values of the four stroke sensors 100 as described above, and the pitch angle θ _p and the roll angle θ _r are short. Since they are acquired at time intervals, their first-order differential values, that is, pitch angular velocity, roll angular velocity, second-order differential values, that is, pitch angular acceleration, and roll angular acceleration related to time can also be acquired from their fluctuations. It is. Therefore, the X-axis direction, Y-axis direction, and Z-axis direction components of the acceleration represented by the above formulas (11), (12), and (13) can be calculated.

The acceleration represented by the above equation (10) is an acceleration depending on the force of the vehicle body pitch and roll, and can be considered as a pitch / roll dependent acceleration. On the other hand, in a traveling vehicle, acceleration that causes the vehicle body to move in translation, that is, translational motion acceleration is generated in the vehicle body due to acceleration / deceleration of the vehicle, turning of the vehicle, and the like. Therefore, if the acceleration generated in the vehicle body portion to which the vertical acceleration sensor 94 is attached is G, the acceleration G can be expressed as the following equation (14) as a vector format. Incidentally, G ₀ is the translational acceleration.

ちなみに、Ｇ_X0、Ｇ_Y0、Ｇ_Z0は、それぞれ、並進運動加速度Ｇ₀のＸ軸方向成分，Ｙ軸方向成分，Ｚ軸方向成分である。 Of the acceleration G shown in the above equation (14), if the component that is the output value of the vertical acceleration sensor 94, that is, the sensor axial direction component is G _s , the sensor axial direction component G _s When the tilt amount is the above-mentioned longitudinal axis angle ρ _x , the transverse axis angle ρ _y , and the vertically axis angle ρ _z , it can be expressed as the following formula (15).

Incidentally, G _X0 , G _Y0 , and G _Z0 are the X-axis direction component, Y-axis direction component, and Z-axis direction component of the translational motion acceleration G ₀ , respectively.

Here, four vertical acceleration sensors 94 are attached to the vehicle body corresponding to the front, rear, left and right wheels. Therefore, if the sensor axial direction component G _s is expressed by an equation for three of the four vertical acceleration sensors 94, the sensor axial direction component G _s of each vertical acceleration sensor 94 is expressed by the following equations (16), ( 17) and (18). Incidentally, the subscripts “1”, “2”, and “3” indicate that each of the three vertical acceleration sensors 94 is provided.

Since the sensor axial direction components G _s1 , G _s2 , and G _s3 of each vertical acceleration sensor 94 are the output values of each vertical acceleration sensor 94, therefore, the above equations (16), (17), and (18) are obtained. By solving as simultaneous equations, the X-axis direction component G _X0 , the Y-axis direction component G _Y0 , and the Z-axis direction component G _Z0 of the translational motion acceleration G ₀ can be calculated. By adding the Z-axis direction component G _Z0 among them and the Z-axis direction component of the pitch / roll-dependent acceleration for each vertical acceleration sensor 94 calculated based on the above formula (13), the following formula ( As in 19), (20), and (21), the vertical accelerations G _z1 , G _z2 , and G _z3 of the part of the vehicle body to which each vertical acceleration sensor 94 is attached are calculated.

In the present system 10, four vertical acceleration sensors 94 are provided, and one of the four acceleration sensors 94 is set as a target sensor, and two sensors (sensors not in a diagonal position) located adjacent to the target sensor. , and to detect the vertical acceleration G _z of the portion subject sensor is attached. Then by changing the target sensor is to detect the vertical acceleration G _z all sites where each of the four vertical acceleration sensor 94 is attached.

The X-axis direction component G _X0 and the Y-axis direction component G _Y0 of the translational motion acceleration G ₀ calculated as described above correspond to the actual longitudinal acceleration G _x and the actual lateral acceleration G _yr described above, respectively. Therefore, according to the present detection process, the actual longitudinal acceleration G _x and the actual lateral acceleration G _yr can be detected without using the longitudinal acceleration sensor 98 and the lateral acceleration sensor 92.

This detection process is performed by executing the third acceleration detection subroutine shown in the flowchart of FIG. In the processing according to this subroutine, first in S61, the vertical axis angle ρ _x , the horizontal axis angle ρ _y , the horizontal axis angle ρ _y , and the vertical axis angle ρ _z for the vertical acceleration sensor 94 and the other two vertical acceleration sensors 94 are determined. The value stored in the storage area described above is recognized by reading. Next, in S62, the pitch angle θ _p is acquired based on the output values of the four stroke sensors 100, and in S63, the roll angle θ _r is acquired based on the output values of the four stroke sensors 100. In subsequent S64, the pitch angular velocity, the roll angular velocity, the pitch angular acceleration, and the roll angular acceleration are obtained by being calculated. In S65, output values G _{s of the} vertical acceleration sensor 94 and the other two vertical acceleration sensors 94 to be detected are acquired. In subsequent S66, the recognized longitudinal axis angle ρ _x , transverse axis angle ρ _y , vertical axis angle ρ _z , acquired pitch angle θ _p , roll angle θ _r , pitch angular velocity, roll angular velocity, pitch angular acceleration , Roll angular acceleration, and vertical acceleration G _z of the part of the vehicle body to which the target vertical acceleration sensor 94 is attached according to the above calculation method based on the obtained output value G _s of the vertical acceleration sensor 94, actual longitudinal acceleration G _x and actual lateral acceleration G _yr are calculated, and further, an output value G _s of the vertical acceleration sensor 94 is acquired at θ _p and S56. The process of S66 is executed, and the process according to the third acceleration detection subroutine ends.

≪Functional structure of controller≫
The controller 82 of the present suspension system 10 that functions by executing the above-described actuator control program can be considered to have a functional configuration as shown in FIG. 11, which is a control block diagram, depending on the execution process. As can be seen from the Figure, the controller 82 is a functional portion to execute the processing of S3, S4, i.e., as a functional unit for determining the damping actuator force component F _G, the damping force determination unit 150, the process of S5, S6 functional portion to execute, that is, as a functional portion to determine the roll-reduction actuator force component F _R, the roll-restraining-force determining portion 152, a functional portion to execute the processing in S7, that is, to determine the pitch restrain actuator force component F _P Each of the function suppression units includes a pitch suppression force determination unit 154. The functional portion to execute the processing in S8, that is, a functional portion to determine their damping actuator force component F _G, roll restraining actuator force component F _R, the target actuator force F _A and the total pitch suppressing actuator force component F _P As a target actuator force determination unit 156.

In addition, the controller 82 is a functional unit that executes the processing of S2, that is, the sprung vertical acceleration G _{z of} the body part to which each vertical acceleration sensor 94 is attached, the actual lateral acceleration G _{yr of} the vehicle body, the actual longitudinal direction of the vehicle body It has a function unit which detects an acceleration G _x. This function unit is attached to each vertical acceleration sensor 94 based on the tilt amount of the sensor axis SL of the vertical acceleration sensor 94, that is, the vertical axis angle ρ _x , the horizontal axis angle ρ _y , and the vertical axis angle ρ _z. The controller 82 has a sensor axis inclination amount-dependent vertical acceleration detection unit 158 because it is a functional unit that detects the sprung vertical acceleration G _z of the vehicle body portion. Furthermore, since the controller 82 also executes the above-described sensor inclination amount measurement program, the controller 82 has a sensor axis inclination amount measurement unit 160 as a functional unit that executes processing according to the program.

1 is a schematic diagram showing an overall configuration of a vehicle suspension system to which a claimable invention is applied. FIG. 2 is a front sectional view showing a spring absorber assembly provided in the vehicle suspension system of FIG. 1. It is a flowchart which shows the actuator control program performed in the suspension system for vehicles of FIG. It is a conceptual diagram which shows the external appearance of the vertical acceleration sensor arrange | positioned in the suspension system for vehicles of FIG. 1, and the inclination of the sensor axis line. It is a schematic diagram which shows the internal structure of the vertical acceleration sensor of FIG. FIG. 5 is a schematic diagram showing the posture of the vehicle body when measuring the inclination of the sensor axis of the vertical acceleration sensor of FIG. 4. 5 is a flowchart showing a sensor axis inclination amount measurement program executed to measure the inclination of the sensor axis of the vertical acceleration sensor of FIG. 4 in the vehicle suspension system of FIG. 1. It is a flowchart which shows the 1st acceleration detection subroutine performed in order to detect a vertical acceleration in the actuator control program of FIG. It is a flowchart which shows the 2nd acceleration detection subroutine performed in order to detect a vertical acceleration in the actuator control program of FIG. It is a flowchart which shows the 3rd acceleration detection subroutine performed in order to detect a vertical acceleration in the actuator control program of FIG. It is a block diagram which shows the function of the actuator electronic control apparatus which manages control of the suspension system for vehicles of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Vehicle suspension system 20: Spring absorber assembly 26: Actuator 54: Electromagnetic motor 80: Actuator electronic control unit (ECU) 82: Controller 88: Vehicle speed sensor 90: Operation angle sensor 92: Lateral acceleration sensor 94: Vertical acceleration sensor 98: Longitudinal acceleration sensor 100: Stroke sensor 102: Inclination amount side processing start switch 150: Damping force determination unit 152: Roll suppression force determination unit 154: Pitch suppression force determination unit 156: Target actuator force determination unit 158: Sensor axis inclination amount Reliable vertical acceleration detection unit 160: Sensor axis inclination measurement unit

Claims (8)

A method of measuring the amount of inclination of an axis of an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis,
A first sensor output value acquisition step of acquiring a first sensor output value, which is an output value of the acceleration sensor in the posture, with the vehicle body as a first posture;
A second sensor output value acquisition step of acquiring a second sensor output value, which is an output value of the acceleration sensor in the posture, in a second posture that is different from the first posture in pitch amount and roll amount;
A sensor tilt amount for calculating the tilt amount of the axis of the acceleration sensor based on the first sensor output value and the second sensor output value, and the roll amount and the pitch amount in each of the first posture and the second posture. A method for measuring the amount of tilt of an acceleration sensor axis including a calculation step.   One of the first posture and the second posture is a posture in which the vehicle body is not pitched and rolled, and the other of the first posture and the second posture is in a state where the vehicle body is rolled and not pitched. The acceleration sensor axis inclination measuring method according to claim 1, wherein the acceleration sensor is an attitude. A vehicle in which the acceleration sensor is attached to the vehicle body has four approaching / separating force generators that are provided corresponding to the four wheels on the front, rear, left, and right sides, and generate a force for approaching and separating the wheels and the vehicle body,
In the first sensor output value acquisition step and the second sensor output value acquisition step, the vehicle body is tilted by the operation of the four approach / separation force generators, and the first sensor output value and the second sensor output value are obtained. The acceleration sensor axis inclination measuring method according to claim 1, wherein the method is an acquisition step.   4. Each of the four approaching / separating force generating devices is an electromagnetic shock absorber that has an electromagnetic motor and generates resistance force against approaching / separating between a wheel and a vehicle body based on the force of the electromagnetic motor. 4. A method for measuring an axial inclination amount of the acceleration sensor according to 1. A method for detecting vertical acceleration by an acceleration sensor that is attached to a vehicle body as a vertical acceleration sensor and detects acceleration in the direction of its own axis,
Recognizing the amount of inclination of the axis of the acceleration sensor;
Obtaining the longitudinal acceleration and lateral acceleration occurring in the vehicle body;
Calculating the vertical acceleration at the site where the acceleration sensor is attached based on the output value of the acceleration sensor, the recognized inclination amount of the axis of the acceleration sensor, and the acquired longitudinal acceleration and lateral acceleration; Vertical acceleration detection method including The upper limit acceleration detecting method further includes a step of acquiring a pitch amount and a roll amount of the vehicle body,
6. The vertical acceleration according to claim 5, wherein the step of calculating the vertical acceleration further calculates the vertical acceleration at a portion where the acceleration sensor is attached based on the acquired pitch amount and roll amount of the vehicle body. Detection method. A method of detecting vertical acceleration in each of the three or more parts by means of three or more acceleration sensors that are attached to the vehicle body at three or more parts and that detect acceleration in the direction of the axis,
Recognizing the amount of inclination of each axis of the three or more acceleration sensors;
Obtaining the pitch amount and roll amount of the vehicle body;
Based on the output value of each of the three or more acceleration sensors, the recognized amount of inclination of the axis of each of the three or more acceleration sensors, and the acquired pitch amount and roll amount of the vehicle body, Calculating the vertical acceleration in at least one part of the parts. The step of calculating the vertical acceleration includes
Based on the output value of each of the three or more acceleration sensors, the recognized amount of inclination of the axis of each of the three or more acceleration sensors, and the acquired pitch amount and roll amount of the vehicle body, 8. The method for detecting vertical acceleration according to claim 7, wherein the vertical acceleration is calculated at least one of longitudinal acceleration and lateral acceleration of the vehicle body along with the vertical acceleration in at least one of the regions.

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