JP6589428B2 - Center of gravity height estimation device - Google Patents

Description

  The present invention relates to a center-of-gravity height estimation device that estimates the center-of-gravity height during travel of a vehicle.

  Conventionally, the height of the center of gravity during travel of the vehicle is estimated, and various alarms, control of the vehicle, and the like are performed based on the estimated height of the center of gravity. As a method for estimating the height of the center of gravity of the vehicle, for example, a method of estimating using the motion of the vehicle in the pitch direction, a method of estimating using a static balance in the roll direction, and the like are known.

  As a method of estimating using the motion in the pitch direction, for example, a method of estimating the distance between the pitch center and the center of gravity from the maximum value of the pitch angle is known (for example, see Patent Document 1).

Special table 2008-522886

  In the technique disclosed in Patent Document 1, it is necessary to specify the maximum value of the pitch angle. For this reason, it is necessary to grasp the pitch angle and the pitch angular velocity. For example, when the pitch angular velocity can be obtained by the gyro sensor, the pitch angular velocity can be integrated to obtain the pitch angle, but noise may be superimposed and the pitch angle accuracy may not be good. Also, when the pitch angle can be calculated by a vehicle suspension height sensor or the like, the pitch angle speed can be obtained by differentiating the pitch angle, but the accuracy of the pitch angular speed may be poor due to the influence of noise.

  On the other hand, when using a static balance in the roll direction, there is a problem that the height of the center of gravity cannot be estimated unless the vehicle turns.

  An object of this invention is to provide the technique which can estimate the gravity center height during driving | running | working of a vehicle easily and appropriately.

  In order to achieve the above-described object, a center-of-gravity height estimation device according to an aspect of the present invention includes a longitudinal acceleration detection unit that detects acceleration in the longitudinal direction of a vehicle, and pitch information detection that detects a pitch angle or a pitch angular velocity of the vehicle. Parameter estimation that estimates the values of the parameters of the state equation by inputting the longitudinal acceleration and pitch angle or pitch angular velocity and applying a nonlinear Kalman filter to the state equation corresponding to the means and the pitch motion model of the vehicle And means for estimating the height of the center of gravity of the vehicle on the basis of the value of the parameter, the rigidity or viscosity damping coefficient in the pitch direction of the vehicle, and the sprung mass of the vehicle.

  In the center-of-gravity height estimation apparatus, the state equation includes the first parameter including the rigidity or viscous damping coefficient in the pitch direction of the vehicle and the inertia moment in the pitch direction, the sprung mass of the vehicle, the height of the center of gravity, and the inertia moment in the pitch direction. The parameter estimation means estimates the value of the first parameter and the second parameter, and the center of gravity height estimation means determines the value of the first parameter and the known stiffness or viscosity in the pitch direction. Based on the damping coefficient, the value of the moment of inertia in the pitch direction is specified, and the height of the center of gravity is estimated based on the value of the second parameter, the value of the moment of inertia in the pitch direction, and the sprung mass of the vehicle. It may be.

  The center-of-gravity height estimation device may further include mass detection means for measuring the sprung mass of the vehicle, and the center-of-gravity height estimation means may estimate the center of gravity height based on the measured sprung mass.

  In the center-of-gravity height estimation apparatus, the mass detection means may detect a sprung mass of a vehicle including a load loaded on the vehicle.

  In the center-of-gravity height estimation device, the mass detection means may detect the sprung mass of the vehicle before the vehicle travels.

  According to the present invention, the height of the center of gravity while the vehicle is traveling can be estimated easily and appropriately.

1 is a schematic overall configuration diagram showing a vehicle according to an embodiment of the present invention. It is a functional block diagram which shows the electronic control unit which comprises the gravity center height estimation apparatus which concerns on one Embodiment of this invention, and a related component.

  Hereinafter, based on an accompanying drawing, a vehicle in which a center-of-gravity height estimation device according to an embodiment of the present invention is mounted will be described. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a schematic overall configuration diagram showing a vehicle according to an embodiment of the present invention. An input shaft (not shown) of the transmission 12 is connected to a crankshaft (not shown) of the engine 10 via a clutch 11 so as to be connected and disconnected. Drive wheels (left and right rear wheels) 16L and 16R are connected to an output shaft (not shown) of the transmission 12 via a propeller shaft 13, a differential 14 and left and right drive shafts 15L and 15R. The vehicle 1 has left and right front wheels (steering wheels) 22L and 22R.

  The vehicle 1 also includes a pair of left and right air springs 18L and 18R provided corresponding to the left and right drive wheels 16L and 16R, and a pair of left and right internal pressure sensors 19L provided corresponding to the air springs 18L and 18R, respectively. , 19R. The internal pressure sensors 19L and 19R constitute a part of the mass detection means.

  The air springs 18L and 18R are interposed between the drive shafts 15L and 15R and a frame (not shown). Air is supplied to the left and right air springs 18L and 18R from an air supply source (not shown).

  The internal pressure sensor 19L is provided in the air piping upstream of the air spring 18L, and detects the internal pressure (air spring pressure) of the air spring 18L. The internal pressure sensor 19R is provided in the air piping upstream of the air spring 18R, and detects the internal pressure (air spring pressure) of the air spring 18R. The air spring pressures detected by the internal pressure sensors 19L and 19R are transmitted to the electrically connected ECU 50, respectively. Since each air spring pressure changes according to the mass of the main body on the spring of the vehicle 1 and the load loaded on the vehicle 1, according to the air spring pressure, the mass of the main body of the vehicle 1 and the load on the load is changed. Can be identified.

  The vehicle 1 includes a gyro sensor 21 as an example of pitch information detection means, a longitudinal acceleration sensor 22 as an example of longitudinal acceleration detection means, a vehicle speed sensor 23, a display device 24, and an electronic control unit (hereinafter referred to as ECU). 50.

The gyro sensor 21 detects an angular velocity (pitch angular velocity) in the pitch direction in the vehicle 1. The longitudinal acceleration sensor 22 is, for example, a pendulum type or a strain gauge type acceleration sensor, and detects the longitudinal acceleration (longitudinal acceleration a _x ) of the vehicle 1 based on the force applied to itself. The vehicle speed sensor 23 detects the traveling speed (vehicle speed) of the vehicle 1 from the rotational speed of the propeller shaft 13. The display device 24 is arranged at a position where the driver can visually recognize, for example, and displays various types of information. The sensor values of these various sensors 20 to 23 are transmitted to the electrically connected ECU 50. In addition, information is displayed on the display device 24 based on data transmitted from the electrically connected ECU 50.

  The ECU 50 performs various controls of the engine 10, the clutch 11, the transmission 12, and the like, and includes a known CPU, ROM, RAM, input port, output port, and the like.

  FIG. 2 is a functional block diagram showing an electronic control unit and related components constituting the center-of-gravity height estimation apparatus according to an embodiment of the present invention.

  The center-of-gravity height estimation device 5 includes a gyro sensor 21, a longitudinal acceleration sensor 22, internal pressure sensors 19L and 19R, a vehicle speed sensor 23, an ECU 50, and a display device 24. The ECU 50 includes a parameter estimation unit 51 as an example of a parameter estimation unit, a mass detection unit 52 that constitutes a part of the mass detection unit, a storage unit 53, and a centroid height estimation unit 54 as an example of a centroid height estimation unit. The speed alarm unit 55 is included as a part of functional elements. In the present embodiment, these functional elements are described as being included in the ECU 50, which is an integral piece of hardware. However, any one of these functional elements may be provided in separate hardware.

The storage unit 53 stores the stiffness K _p (N / rad) in the pitch direction of the vehicle 1 or the viscous damping coefficient C _p (Ns / m) in the pitch direction of the vehicle 1. The stiffness K _p and the viscous damping coefficient C _p may be design values of the vehicle 1 or values detected experimentally using the vehicle 1.

  The parameter estimation unit 51 applies a nonlinear Kalman filter (EKF (extended Kalman filter), UKF (anne) to a state space model (state equation) derived based on a motion equation of a motion model (pitch motion model) in the vehicle pitch direction. By applying an algorithm such as a sent Kalman filter), the value of the parameter of the state equation is sequentially estimated and passed to the centroid height estimation unit 54.

  Next, the equation of motion related to the pitch motion in the vehicle 1 and the state equation derived based on the equation of motion related to the processing of the parameter estimation unit 51 will be described in detail.

  Since the pitch motion of the vehicle 1 is a change in the posture of the vehicle body, it can be approximated by a model that considers the vehicle body (sprung), and the motion equation of the pitch motion model is as shown in Equation (1).

Here, J _p represents the moment of inertia in the pitch direction, C _p represents the viscous damping coefficient in the pitch direction, K _p represents the rigidity in the pitch direction, θ _p represents the pitch angle, θ ^· _p (in equation (1), dot (•) above θ, for convenience in the description, this is indicated for convenience) indicates the pitch angular velocity, and θ ^·· _p (in equation (1) above θ Two dots (...) (Denoted in this way for convenience in the description) indicate pitch angular acceleration. W _f indicates a load (N) acting on the front wheel of the vehicle 1 when stationary, W _r indicates a load (N) acting on the rear wheel of the vehicle 1 when stationary, and L _f indicates stationary It indicates the length of the horizontal direction from the center of gravity position to the front wheel (m) when, L _r represents the horizontal length to the rear wheel (m) to the center of gravity of the stationary state. Further, m represents the vehicle body sprung mass (kg), _{a x} denotes the longitudinal acceleration _{^{(m / s 2), h}} CG represents the center of gravity height.

  The first and second terms on the right side of the equation of motion of this pitch motion model represent moments at rest and are zero because they are balanced at rest.

  When a state equation for applying the nonlinear Kalman filter is derived from the motion equation of the pitch motion model shown in Equation (1), the state equation becomes as shown in Equation (2).

  Here, the matrices A, B, and C and the variables x and u in the state equation shown in Expression (2) are as shown below Expression (2). In this example, the value of the matrix C is an example when the gyro sensor 21 that detects the pitch angular velocity is used. The value of the matrix C differs depending on the type of sensor that detects information about pitch (pitch information). The matrices w and v are system noise and observation noise, respectively.

The parameter estimation unit 51 sequentially receives inputs of u (= a _x : longitudinal acceleration) and y (θ ^· _p (pitch angular velocity) in the example of Expression (2)) and applies a nonlinear Kalman filter ( That is, the parameters in the state equation are estimated sequentially using a nonlinear Kalman filter algorithm. Note that only the pitch angle may be input as y, or the pitch angle and the pitch angular velocity may be input.

In the present embodiment, the parameter estimation unit 51, as shown in Expression (3), Expression (4), and Expression (5), −K _p / J _p (an example of the first parameter), −C _p / J _p (An example of the first parameter), -ma _x h _CG (an example of the second parameter) values a ₁ , a ₂ , and b ₁ (in this description, for convenience, they are expressed in this way), respectively. To do. The parameter estimation unit 51 notifies the estimated parameter values a ₁ , a ₂ , and b ₁ to the center of gravity height estimation unit 54.

  For example, when the vehicle 1 is stopped, the mass detector 52 calculates the total of the main body of the vehicle 1 and the load loaded on the vehicle 1 based on the air spring pressure detected by the internal pressure sensors 19L and 19R. The sprung mass m is detected and notified to the center-of-gravity height estimation unit 54.

The center-of-gravity height estimation unit 54 includes the values a ₁ , a ₂ , b _{1 of the} parameters notified from the parameter estimation unit 51, the sprung mass m notified from the mass detection unit 52, and the pitch direction stored in the storage unit 53. Based on the stiffness K _p (or the viscous damping coefficient C _p in the pitch direction), the center of gravity height h _CG of the vehicle 1 is sequentially estimated, and the result is notified to the speed warning unit 55.

Here, the estimation method of the center-of-gravity height _hCG of the center-of-gravity height estimation unit 54 will be specifically described.

When Expression (5) including the center of gravity height h _CG is modified, Expression (6) is obtained.

In Expression (6), since the values of the sprung mass m and the parameter value b ₁ are already specified, the center-of-gravity height h _CG can be obtained if the moment of inertia J _{p in the} pitch direction is determined.

Here, the moment of inertia J _p is as shown in Equation (7) when the stiffness K _p is used. When this equation (7) is substituted into equation (6), the center-of-gravity height h _CG is expressed using the stiffness K _p as shown in equation (8). In Expression (8), since the values of the sprung mass m and the parameter values a ₁ and b ₁ are already specified, when the stiffness K _p is stored in the storage unit 53, the values are used. it is possible to estimate the height of the center of gravity h _CG Te. Therefore, when the stiffness K _p is stored in the storage unit 53, the center-of-gravity height estimation unit 54 estimates the center-of-gravity height h _CG using Equation (8).

On the other hand, the moment of inertia J _p is represented by the equation (9) when the viscous damping coefficient C _p is used. When this equation (9) is substituted into equation (6), the center-of-gravity height h _CG is expressed using the viscous damping coefficient C _p as shown in equation (10). In Expression (10), since the values of the sprung mass m and the parameter values a ₂ and b ₁ have already been specified, when the viscosity damping coefficient C _p is stored in the storage unit 53, the values thereof are used. it is possible to estimate the height of the center of gravity h _CG used. Therefore, when the viscosity damping coefficient C _p is stored in the storage unit 53, the center-of-gravity height estimation unit 54 estimates the center-of-gravity height h _CG using Equation (10). Note that the center of gravity height h _CG can be estimated from one of the stiffness K _{p and the} viscosity damping coefficient C _p , so only one of them may be stored in the storage unit 53, but the value can be easily specified. In a certain point, it is preferable to store the stiffness K _p in the storage unit 53.

Based on the vehicle speed from the vehicle speed sensor 23 and the center-of-gravity height h _CG notified from the center-of-gravity height estimation unit 54, the speed warning unit 55 has a high risk of occurrence of rollover when the vehicle 1 turns. If it is determined that the speed is high in danger, an alarm indicating that the speed is high in danger such as rollover is displayed on the display device 24.

  As described above, according to the center-of-gravity height estimation apparatus 5 according to the present embodiment, the center-of-gravity height can be estimated using only at least one of the pitch angle and the pitch angular velocity, and thus a plurality of sensors for detecting them are prepared. When there is no need, and there is only one sensor, it is not necessary to calculate the pitch angular velocity based on the pitch angle or calculate the pitch angle based on the pitch angular velocity, and noise is mixed at the time of calculation Can be appropriately prevented, and the height of the center of gravity can be estimated with high accuracy.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably and can implement.

For example, in the above-described embodiment, an example in which the speed alarm is performed using the estimated center-of-gravity height h _CG has been described. However, the present invention is not limited to this, for example, the vehicle 1 based on the estimated center-of-gravity height h _CG The vibration in pitching of the vehicle 1 may be suppressed by controlling the height position of at least one suspension on the front wheel side or the rear wheel side.

  In the above embodiment, the pitch angular velocity is measured by the gyro sensor 21, and the parameters are estimated using the pitch angular velocity. For example, the heights of the suspensions on the front wheel side and the rear wheel side are measured. It is also possible to provide a height sensor that detects the pitch angle of the vehicle 1 based on the detection values of the height sensors on the front wheel side and the rear wheel side, and estimate the parameters using the pitch angle.

  In the above embodiment, the mass of the main body on the spring of the vehicle 1 and the load loaded on the vehicle 1 is detected based on the air spring pressure detected by the internal pressure sensors 19L and 19R. However, the present invention is not limited to this, and a sensor for detecting the displacement amount of the suspension is provided, and the mass of the main body on the spring of the vehicle 1 and the load loaded on the vehicle 1 is detected based on the displacement amount. You may make it do.

  Further, in the above embodiment, the traveling speed (vehicle speed) of the vehicle 1 is detected from the rotational speed of the propeller shaft 13, but the present invention is not limited to this, for example, the output shaft or the wheel of the transmission 12. It is also possible to provide a sensor for detecting the rotational speed such as the vehicle speed and detect the vehicle speed from the detected rotational speed.

DESCRIPTION OF SYMBOLS 1 Vehicle 5 Center of gravity height estimation apparatus 10 Engine 11 Clutch 12 Transmission 13 Propeller shaft 14 Differential device 15L, R Drive shaft 16L, R Drive wheel 18L, R Air spring 19L, R Internal pressure sensor 21 Gyro sensor 22 Longitudinal acceleration sensor 23 Vehicle speed Sensor 24 Display device 50 ECU
51 Parameter Estimation Unit 52 Mass Detection Unit 53 Storage Unit 54 Center of Gravity Height Estimation Unit

Claims (4)

Longitudinal acceleration detection means for detecting the longitudinal acceleration of the vehicle;
Pitch information detection means for detecting the pitch angle or pitch angular velocity of the vehicle;
A parameter that estimates the value of the parameter of the state equation by inputting the acceleration in the front-rear direction and the pitch angle or the pitch angular velocity and applying a nonlinear Kalman filter to the state equation corresponding to the pitch motion model of the vehicle An estimation means;
The value of the parameter, a rigid or viscous damping coefficient of the pitch direction of the vehicle, on the basis of the sprung mass of the vehicle, have a center of gravity height estimation means for estimating the height of the center of gravity of the vehicle,
The equation of state includes a first parameter including a stiffness or viscous damping coefficient in the pitch direction of the vehicle and a moment of inertia in the pitch direction, and a second parameter including a sprung mass of the vehicle, a height of the center of gravity, and a moment of inertia in the pitch direction. Parameters
The parameter estimating means estimates values of the first parameter and the second parameter;
The center-of-gravity height estimation means specifies the value of the moment of inertia in the pitch direction based on the value of the first parameter and the known stiffness or viscosity damping coefficient in the pitch direction, the value of the second parameter, The center-of-gravity height estimation device that estimates the center-of-gravity height based on the value of the moment of inertia in the pitch direction and the sprung mass of the vehicle . Further comprising mass detection means for measuring the sprung mass of the vehicle;
The center-of-gravity height estimation device according to claim 1, wherein the center-of-gravity height estimation means estimates the center of gravity height based on the sprung mass . The center-of-gravity height estimation device according to claim 2 , wherein the mass detection means detects a sprung mass of the vehicle including a load loaded on the vehicle . The center-of-gravity height estimation device according to claim 3 , wherein the mass detection means detects a sprung mass of the vehicle before the vehicle travels .

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