Center of gravity height estimator

Abstract

Estimation device (10, 20) for the height of the center of mass, comprising: a roll moment calculation unit (122) configured to calculate the roll moment of a sprung part in a vehicle (1) based on the load capacities of left and right suspensions provided on the vehicle (1); a lateral acceleration measuring unit (123) configured to measure lateral acceleration, which is an acceleration in a width direction of the vehicle (1); a mass measuring unit (124) configured to measure the mass of the sprung member; a transfer function calculation unit (201) configured to calculate a transfer function of the roll moment with respect to the lateral acceleration; and a center of mass height calculation unit (125, 126, 202) configured to divide a gain of the transfer function by the mass of the sprung part to calculate a height from a roll center of the vehicle (1) to a center of mass of the sprung part, characterized in that the center of mass height calculation unit (125, 126, 202) divides a transfer function gain corresponding to a frequency equal to or less than a predetermined value among the transfer function gains by the mass of the sprung part to calculate the height from the roll center of the vehicle (1) to the center of mass of the sprung part.

Description

Technical area

[0001] The present disclosure relates to a center of mass height estimating device for estimating a height of a center of mass in a vehicle such as a commercial vehicle. State of the art

[0002] To prevent a vehicle from tipping over, it is important to estimate the height of the vehicle's center of gravity. Since the position of the center of gravity of the entire vehicle changes significantly depending on the loading condition, especially in a commercial vehicle, it is important to estimate the height of the center of gravity when a load is loaded.

[0003] For example, as a method for estimating the height of a center of gravity in a vehicle, the following proposals have been made (referring to Patent Literature 1).

[0004] That is, in Patent Literature 1, a suspension device capable of adjusting the height of a roll center is provided, wherein the rolling behavior is made constant by adjusting a height of a roll center of front and rear wheels in a case where a loading state changes.

[0005] Specifically, a height of a desired roll center of front and rear wheels is achieved, wherein an actuator of the suspension device is controlled so that a height reaches the height of the desired roll center.

[0006] Here, the height of the target rolling center of the front and rear wheels is determined by the following methods (referring to paragraphs

[0016] to

[0017] of Patent Literature 1).

[0007] That is, a height of a center of mass of an occupant in a state where the occupant gets on the vehicle is assumed to be constant, and a height of a center of mass of a suspended vehicle body in the state where the occupant gets on the vehicle is obtained based on a change in the mass of the suspended vehicle body in the state where the occupant gets on the vehicle and a height of a center of mass and the mass of the suspended vehicle body in an empty state. Then, the height of the target roll center required to maintain the roll moment corresponding to the lateral rotational acceleration in a reference state is obtained, and the height of the target roll center is distributed among the front and rear wheels.

[0008] Patent Literature 2 describes a device for estimating the center of gravity position of a vehicle with a computing device that evaluates a pitching movement of the vehicle occurring under the influence of longitudinal acceleration and / or a rolling movement of the vehicle occurring under the influence of lateral acceleration to estimate the center of gravity position. Citation listPatent document Patent literature 1: JP 2007 - 22 287 A Patent literature 2: DE 102005062286A1 Summary of the inventionTechnical problem

[0009] In the method described in Patent Literature 1, the height of the occupant's center of gravity is constant in a state where the occupant gets into the vehicle. However, in a commercial vehicle primarily used for transporting cargo, a cargo location or mass corresponding to the occupant of Patent Literature 1 changes significantly each time the commercial vehicle stops at a distribution point or the like. Thus, the height of the cargo's center of gravity is not constant in an actual commercial vehicle.

[0010] It is an object of the present disclosure to provide a center of gravity height estimating device capable of estimating a center of gravity height of a sprung part of the vehicle with higher accuracy even in a case where an arrangement or mass of a cargo loaded on the sprung part of the vehicle changes variously and a center of gravity height of the cargo changes. Solution to the problem

[0011] A center of gravity height estimation device of the present disclosure includes: a roll moment calculation unit configured to calculate the roll moment of a sprung member in a vehicle based on the load capacities of the left and right suspensions provided on the vehicle; a lateral acceleration measurement unit configured to measure lateral acceleration, which is an acceleration in a width direction of the vehicle; a mass measurement unit configured to measure the mass of the sprung member; a transfer function calculation unit configured to calculate a transfer function of the roll moment with respect to the lateral acceleration;and a mass height calculation unit configured to divide a gain of the transfer function by the mass of the sprung part to calculate a height from a roll center of the vehicle to a center of mass of the sprung part;

[0012] According to the invention, the calculation unit for the height of the center of mass is a transfer function gain corresponding to a frequency equal to or less than a predetermined value among the transfer function gains, divided by the mass of the sprung part to calculate the height from the roll center of the vehicle to the center of mass of the sprung part.

[0013] The center of mass height calculation unit may divide statistics obtained from a plurality of gains of the transfer function corresponding to a frequency equal to or less than the predetermined value by the mass of the sprung part to calculate a height from a roll center of the vehicle to the center of mass of the sprung part.

[0014] Each of the left and right suspensions is an air suspension, and the roll moment calculation unit can calculate the roll moment based on a difference between the displacements of the left and right suspensions and a difference between the pressures in the left and right suspensions. Advantageous effects of the invention

[0015] According to the center of mass height estimating device of the present disclosure, a center of mass height of the sprung part of the vehicle can be estimated with higher accuracy even when an arrangement or mass of a cargo loaded on the sprung part of a vehicle changes variously and a height of a center of mass of the cargo changes. Short description of the drawings [ Fig. 1] Fig. 1 is a schematic diagram of a vehicle provided with a center of gravity height estimating device according to a first embodiment, as viewed from a vehicle rear. [ Fig. 2] Fig. Figure 2 is a graphic representation of the moment around a roll center of the vehicle. [ Fig. 3] Fig. 3 is a block diagram showing a configuration of the center of mass height estimator. [ Fig. 4] Fig. Figure 4 is a flowchart showing the operation of the center of mass height estimator. [ Fig. 5] Fig. Figure 5 is a graph showing an approximate straight line of roll moment / lateral acceleration. [ Fig. 6A] Fig. Figure 6A is a graph schematically showing a relationship between lateral acceleration and roll moment. [ Fig. 6B] Fig. Figure 6B is a graph schematically showing a relationship between lateral acceleration and roll moment. [ Fig. 7] Fig. 7 is a block diagram showing a configuration of a center of gravity height calculation unit according to a second embodiment. [ Fig. 8] Fig. Figure 8 is a graph schematically showing a gain and a phase of a frequency transfer function. [ Fig. 9] Fig. Figure 9 is a flowchart showing the operation of the center of mass height estimator. Description of embodiments[First embodiment]

[0016] In the following, a first embodiment of the present disclosure will be described with reference to the Fig. 1 to 5.

[0017] Fig. 1 is a schematic diagram of a vehicle 1 provided with a center of gravity height estimating device according to a first embodiment of the present disclosure, as viewed from a vehicle rear side.

[0018] The vehicle 1 includes an unsprung part 2, a left rear wheel 3L and a right rear wheel 3R mounted on the unsprung part 2, air springs 4L, 4R as an example of left and right air springs provided on the unsprung part 2, and a sprung part 5 supported by the left and right air springs 4L, 4R. A load 6 is loaded onto the sprung part 5.

[0019] Fig. 2 is a graphic representation of the moment around a roll center (RC) of the vehicle 1. As in Fig. 2, for vehicle 1, the moment about the roll center RC satisfies the following equation (1). In equation (1), M x the rolling moment of the sprung part 5, h sm is a height from the roll center RC to a center of mass Q of the sprung part 5, where F y is a centrifugal force acting on the spring-loaded part 5. In addition, m smthe mass of the sprung part 5, G y the lateral acceleration, which is an acceleration in a width direction of the vehicle 1, and M const an offset amount of the rolling moment of the sprung part 5 due to the load 6 being laterally displaced and loaded. Mx=hsm⋅Fy+Mconst

[0020] The centrifugal force F acting on the resilient part 5 y satisfies the following equation (2). Fy=msm⋅Gy

[0021] Equation (3) is obtained by substituting equation (2) into equation (1). Mx=hsm⋅msm⋅Gy+Mconst

[0022] An equation created at a time a of equation (3) is represented by equation (4) if a symbol that changes with time is given a suffix a. An equation created at a time b different from time a is represented by equation (5) if a symbol that changes with time is given a suffix b. Since it is taken into account here that the arrangement and mass of the load 6 do not change during the journey between the distribution support points, the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung mass 5, the mass m sm the sprung mass 5 and the offset circumference M const the rolling moment of the sprung part 5 is considered constant. Mxa=hsm⋅msm⋅Gya+Mconst Mxb=Hsm⋅msm⋅Gyb+Mconst

[0023] The following equation (6) is obtained by taking a lateral difference of equation (4) and equation (5) and for h sm modified, where the height h sm from the roll center RC to the center of mass Q of the sprung part 5. In equation (6), D is a proportional coefficient determined by a change in the roll moment M x of vehicle 1 with respect to a change in the lateral acceleration G y is shown. hsm=1msm⋅(Mxb−Mxa)(Gyb−Gya)=1msm⋅ΔMxΔGy=1msm⋅D

[0024] In a case where an air suspension is used for a rear axle suspension, the rolling moment M X can also be obtained from a displacement and a pressure of the air suspension of the rear shaft using the following equation (7). In equation (7), K φ13an integrated roll stiffness, which is the sum of the roll stiffness of the front and rear suspensions, excluding the air suspension, and is a constant value unique to the vehicle. In equation (7), M s the roll moment supported by the air suspensions 4L, 4R of the rear wheels 3L, 3R. φ2 is a suspension roll angle obtained from a distance between the left and right air suspensions 4L, 4R and a difference hd between the up and down displacements of the left and right air suspensions 4L, 4R. Mx=Kφ13⋅φ2+Ms

[0025] Here M can s in equation (7) by means of equation (8) based on a distance Trd2 between the left and right air suspensions 4L, 4R and a difference between the load capacities P L , P R of the air suspensions. Ms=Trd22⋅(PL−PR)

[0026] In a case where a mechanical spring such as a leaf spring or a coil spring is used for the front and rear suspension without using the air suspension, M s in equation (7) is set to 0, where the rolling moment M x of the sprung part can be obtained using equation (9). Mx=Kφ13⋅φ2

[0027] In a case where a mechanical spring such as a leaf spring or a coil spring is used for the front and rear suspension without using the air suspension, and displacements of the front, rear, left and right suspensions are known, the rolling moment M x of the sprung part can also be obtained using equation (10).

[0028] Equation (10) applies to a four-wheeled vehicle. In equation (10), F Z1L a load capacity of a left suspension of the front shaft on the sprung part, where FZ1R a load capacity of a right suspension of the front shaft on the sprung part, F Z2L a load capacity of a left suspension of the rear shaft on the sprung part and F Z2R is a load capacity of a right suspension of the rear axle on the sprung part. The load capacities Fz of these suspensions are derived from the displacement of each suspension according to a previously generated map or the like. Mx=Trd12⋅(FZ1L−FZ1R)+Trd22⋅(FZ2L−FZ2R)

[0029] Although it is assumed that the vehicle has four wheels, the load capacity can also be obtained using an equation similar to equation (10) if the vehicle has six or eight wheels.

[0030] The vehicle 1 is provided with a center of mass height estimating device 10 for estimating a height of a center of mass of the sprung part 5.

[0031] Fig. 3 is a block diagram showing a configuration of the center of mass height estimating device 10.

[0032] The center of gravity height estimator 10 includes a storage unit 11 and a control unit 12. The storage unit 11 includes a storage medium such as a read-only memory (ROM), a random access memory (RAM), or a hard disk. The storage unit 11 stores programs to be executed by the control unit 12. The control unit 12 is, for example, a central processing unit (CPU) and functions as a load capacity measuring unit 121, a roll moment calculating unit 122, a lateral acceleration measuring unit 123, a mass measuring unit 124, a center of gravity height calculating unit 125, and a center of gravity height above the ground calculating unit 126 by executing programs stored in the storage unit 11.

[0033] The load capacity measuring unit 121 measures the load capacities P L , PR of the left and right air suspensions 4L, 4R. For example, the load capacities P L , P R of the left and right air suspensions 4L, 4R based on pressures in the left and right suspensions 4L, 4R, respectively. The roll moment calculation unit 122 calculates the roll moment based on a difference between the load capacities P L , P R of the left and right air suspensions 4L, 4R and a difference between the pressures of the left and right suspensions. More specifically, the roll moment calculation unit 122 calculates the roll moment M x of the sprung part 5 based on the load capacities P L , P Rof the left and right air suspensions 4L, 4R, for example, by the above equations (7) and (8). In a case where a mechanical spring such as a leaf spring or a coil spring is used in combination with the air suspension, the roll moment calculation unit 122 obtains a load capacity of the mechanical spring from the displacements of the left and right air suspensions according to a previously prepared map or the like. Further, the roll moment calculation unit 122 calculates the roll moment M x of the sprung part 5 on the basis of the relative load capacities and the distance Trd2 between the left and right air suspensions 4L, 4R, for example, by the above equations (7) to (10).

[0034] The lateral acceleration measuring unit 123 measures the lateral acceleration G y of the vehicle 1. The mass measuring unit 124 measures the mass m sm of the sprung part 5. The mass measuring unit 124 measures the mass msm of the sprung mass 5 based on the displacement of each suspension of the vehicle 1.

[0035] The calculation unit for the height of the center of mass 125 calculates a proportional coefficient D of the rolling moment M x of the sprung part 5 for lateral acceleration G y and calculates a value obtained by dividing the proportional coefficient D by the mass m sm of the sprung part 5 as the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5.

[0036] The calculation unit 126 for the height of the center of mass above the ground adds a height H RC from the ground to the roll center RC to the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5, which is calculated by the center of mass height calculation unit 125, so as to obtain a height H CGfrom the ground to the center of mass Q of the sprung part 5.

[0037] Next, the operations of the center of mass height estimating device 10 will be described with reference to a flowchart of Fig. 4. First, the load capacity measuring unit 121 measures the load capacities P L , P R of the left and right air suspensions 4L, 4R (step S1). Next, the load capacity measuring unit 121 measures the difference h d between the up and down displacements of the left and right air suspensions 4L, 4R (step S2).

[0038] The roll moment calculation unit 122 calculates the roll moment M supported by the air suspensions 4L, 4R s by means of the load-bearing capacities P L , P Rof the left and right air suspensions 4L, 4R (step S3). Furthermore, the roll moment calculation unit 122 calculates the suspension roll angle φ2 using the difference hd between the displacements of the left and right air suspensions 4L, 4R (step S4). The roll moment calculation unit 122 calculates the roll moment M x of the sprung part 5 according to equation (7) (step S5). The lateral acceleration measuring unit 123 measures the lateral acceleration G y of vehicle 1 (step S6).

[0039] Furthermore, the center of mass height calculation unit 125 repeats steps S1 to S6 until a predetermined time period elapses after the load capacity measurement unit 121 starts measuring the load capacities PL, PR (step S7). That is, steps S1 to S6 are performed at times t1, t2, t3... t n carried out while the vehicle is stopped, or driving and rolling moment M x1 , Mx2 , M x3 ... M xn and lateral acceleration G y1 , G y2 , G y3 ... G yn are measured at times t1 to t n The specified time period is a time period for the calculation unit for the height of the center of mass 125, for example, to calculate the load capacities P L , P R which is used to obtain the height h sm from the roll center RC of vehicle 1 to the center of mass Q of the sprung part, with a specified accuracy.

[0040] Fig. 5 is a graph showing an approximately straight line from “roll moment M x / lateral acceleration G y “ shows. As in Fig. As shown in Figure 5, the center of mass height calculation unit 125 generates a graph with the lateral acceleration G y as the horizontal axis and the rolling moment M xas the vertical axis, with the values obtained in steps S5 and S6 plotted on the graph to form an approximately straight line from M x / G y by a least squares method. A slope of the approximate straight line is assumed to be the proportional coefficient D (step S8).

[0041] The mass measuring unit 124 measures the mass m sm of the vehicle 1 (step S9). The center of mass height calculation unit 125 calculates the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part according to equation (3) (step S10). Furthermore, the center of mass height calculation unit 126 calculates the height H CG from the ground to the center of mass Q of the sprung part 5 by means of the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 (step S11). [Effects of the first embodiment]

[0042] As described above, according to the center of mass height estimating device 10 of the present embodiment, the proportional coefficient D of the roll moment M x of the sprung part 5 for lateral acceleration G y where the value obtained by dividing the proportional coefficient D by the mass m sm of the sprung part 5 is obtained as the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5. Even in a case where the vehicle stops at the distribution support points or the like, the arrangement or mass of the load changes differently and the center of mass of the load changes, therefore, the height from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 can be calculated simply by measuring the load capacities P L , P Rof the left and right air suspensions 4L, 4R, the difference hd between the displacements and the lateral acceleration G y can be estimated. The height from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 can be easily estimated during normal driving without the need for special external equipment.

[0043] Since the proportional coefficient D of the rolling moment Mx to the lateral acceleration G y by the least squares method, the height of the center of mass of the sprung part 5 can be estimated with high accuracy, even if the measured values of the lateral acceleration G y and the rolling moment M x vary. [Second embodiment]

[0044] In the first embodiment, an example was described in which the proportional coefficient D of the rolling moment M xwith respect to the lateral acceleration G y by the least squares method. In a second embodiment, however, an example is described in which a gain D' of a frequency transfer function of the rolling moment M x with respect to the lateral acceleration G y is calculated.

[0045] The Fig. are representations that schematically show a relationship between the lateral acceleration G y and the rolling moment M x and variations of the lateral acceleration G y and the rolling moment M x show. Fig. Figure 6A shows that the lateral acceleration G y and the rolling moment M x oscillate in the same phase, whereby Fig. 6B shows that the rolling moment M x with a delay of a phase Δ compared to the lateral acceleration G y swings.

[0046] In the graphics of Fig. 6A and Fig. 6B, the horizontal axis represents time and the vertical axis represents amplitude. In the examples of Fig. 6A and Fig. 6B shows the lateral acceleration G y a sine waveform of amplitude 1, as indicated by a solid line, where the rolling moment M x shows a sine waveform of amplitude 2, as indicated by a dashed line. As in Fig. 6A is when the lateral acceleration G y and the rolling moment M x in phase, the proportional coefficient D, which is determined by a change in the rolling moment M x of vehicle 1 up to a change in lateral acceleration G y represented in equation (6), 2.

[0047] As in Fig. As shown in Figure 6B, the proportional coefficient D varies with time when the rolling moment Mx with a delay of a phase Δ compared to the lateral acceleration G y oscillates. For example, when the center of mass height calculation unit 125 calculates the proportional coefficient D by the least squares method, the proportional coefficient D is smaller compared to a case where the lateral acceleration G y and the rolling moment M x in phase, so that the accuracy of the proportional coefficient D may be lower.

[0048] In a case where the rolling moment M X is affected by noise due to unevenness of a road surface, the accuracy of the proportional coefficient D tends to be lower when the proportional coefficient D is calculated by the least squares method.

[0049] Therefore, the center of mass height estimation system according to the second embodiment calculates the gain D' of the roll moment transfer function M x with respect to the lateral acceleration G y . The gain D' is determined by a phase difference between the lateral acceleration G y and the rolling moment M x not affected. Therefore, it is possible to reduce the calculation accuracy of the height h sm from the roll center RC of vehicle 1 to the center of mass Q of the sprung part, resulting from the phase difference between the lateral acceleration G y and the rolling moment M x results.

[0050] The center of mass height estimation system according to the second embodiment calculates the height h smfrom the roll center of the vehicle 1 to the center of mass Q of the sprung part 5 by means of a low-frequency component of the gain D' of the frequency transfer function. Since the center of mass height estimation system excludes a high-frequency component of the gain D', which is susceptible to noise due to unevenness of a road surface and electrical noise during A / D conversion, by using the low-frequency component of the gain D' of a frequency transfer function F, the height h sm from the roll center RC to the center of mass Q of the sprung part 5 can be calculated with higher accuracy.

[0051] Fig. 7 is a block diagram showing a configuration of a center of gravity height estimating device 20 according to the second embodiment.

[0052] Compared to the estimator for the height of the center of mass 10 in Fig. 3, the center of gravity height estimating device 20 is different in that it further includes a transfer function calculation unit 201 and a center of gravity height calculation unit 202 in the control unit 12, but does not include the center of gravity height calculation unit 125. Hereinafter, in the center of gravity height estimating device 20 according to the second embodiment, the same functional blocks as those in the center of gravity height estimating device 10 according to the first embodiment are denoted by the same reference numerals, and a description thereof is omitted.

[0053] The transfer function calculation unit 201 calculates a frequency transfer function of the rolling moment M x with respect to the lateral acceleration G yHere, a case is described in which the transfer function calculation unit 201 calculates the frequency transfer function using an average periodogram method. A cross spectrum H MG the lateral acceleration G y and the rolling moment M x is expressed by the following equation (11). In equation (11), R(M x ) a Fourier transformation of the rolling moment M x . S(G y ) is based on a Fourier transformation of the lateral acceleration G y and S*(G y ) to a complex conjugate of S(G y ) set. HMG=R(Mx)⋅S*(Gy)

[0054] An automatic performance spectrum HGG of the lateral acceleration G y is expressed by the following equation (12). HGG=S(Gy)⋅S*(Gy)

[0055] In equation (12) S*(G y ) is a complex conjugate of S(Gy ). In this case, the frequency transfer function F of the rolling moment M x with respect to the lateral acceleration G y represented by the following equation (13). F=HMGHGG=R(Mx)S(Gy)

[0056] The calculation unit for the height of the center of mass 202 divides the gain D' of the frequency transfer function F by the mass m sm of the spring-loaded part 5, so as to adjust the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part. The operation of the center of mass height calculation unit 202 is explained with reference to Fig. 8 described.

[0057] Fig. Figure 8 is a graph schematically showing the frequency transfer function F of the rolling moment M x with respect to the lateral acceleration G y shows. An upper graphic in Fig. Figure 8 is a double logarithmic graph showing frequency on the horizontal axis and gain on the vertical axis on a logarithmic scale. A lower graph in Fig. Figure 8 is a single logarithmic graph showing frequency on the logarithmic scale on the horizontal axis and phase on the vertical axis. As shown in the upper graph of Fig. 8, the gain D' of the frequency transfer function F with a maximum value of about 2 at a frequency of 0.01 Hz to 0.3 Hz, indicated by a circle C in Fig. 8, is essentially constant and decreases as the frequency increases. The high-frequency component of the gain D' of the frequency transfer function F exhibits electrical noise during A / D conversion and noise due to uneven road surfaces during straight-line driving.

[0058] Therefore, in order to remove the influence of noise, the center of mass height calculation unit 202 detects a gain D' corresponding to a frequency equal to or less than a predetermined value, as indicated by the circle C in Fig. 8, among the gains D' of the frequency transfer function F. The given value is an upper limit of the gain D' of the frequency transfer function F, which has been experimentally confirmed as usable, for example, to determine the height h smfrom the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5, and is, for example, at most 1 Hz. In a case where there are a plurality of gains D' of the frequency transfer function, each corresponding to a frequency equal to or lower than the predetermined value, the center of mass height calculation unit 202 acquires statistics of the plurality of gains D' of the frequency transfer function. The statistics are, for example, an average value, but may also be a median or a mode.

[0059] The description now returns to Fig. 7. Similar to equation (6), the calculation unit for the height of the center of mass 202 divides the gain D' of the frequency transfer function F by the mass m sm of the spring-loaded part 5, so as to adjust the height h smfrom the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5, as shown in the following equation (14). hsm=1msm⋅D′

[0060] The center of mass height calculation unit 202 reads a permissible range of the gain D' of the frequency transfer function F from the memory 11. The permissible range of the gain D' is, for example, a possible range of the gain D' previously determined by experiments. The center of mass height calculation unit 202 compares the read permissible range with the statistics of the gain D' for each of the times t1, t2, t3...t n calculated frequency transfer function F while the vehicle is stopped or moving. The times t1, t2, t3... t n For example, points in time are determined at predetermined time intervals.

[0061] The calculation unit for the height of the center of mass 202 further calculates an average value over the times t1 to t n for statistics each having a value within the permissible range, among the statistics of the gain D' of the frequency transfer function F, which for each of the times t1, t2, t3... t n The calculation unit for the height of the center of mass 202 divides the average value over the times t1 to t n by the mass m sm of the spring-loaded part 5, so as to adjust the height h sm from the roll center RC of vehicle 1 to the center of mass Q of the sprung part 5.

[0062] The steps S1 to S7, S9 and S11 and the steps S101 to S104 in Fig. 9 form a flowchart showing the operation of the center of mass height estimator 20. Steps S1 to S6 and step S11 are the same as in the flowchart of Fig. 4, the description of which is omitted.

[0063] In step S101, the transfer function calculation unit 201 calculates the frequency transfer function F using the rolling moment M x and the lateral acceleration G yof the air suspensions 4L, 4R by an average periodogram method (step S101). Next, the transfer function calculation unit 201 acquires a gain D' corresponding to a frequency of a low-frequency component among the gains D' of the frequency transfer function F, for example, a gain D' corresponding to a frequency equal to or less than a predetermined value. In a case where there are a plurality of gains D' each corresponding to a frequency equal to or less than the predetermined value, an average value of the gains D' is calculated (step S102).

[0064] The center of mass height calculation unit 202 repeats steps S1 to S6, S101 and S102 until a predetermined period of time elapses since the load capacity measuring unit 121 has started measuring the load capacities P L , P Rbegins (step S7). That is, steps S1 to S6, S101 and S102 are executed at times t1, t2, t3... t n carried out while the vehicle is stopped or moving, with the frequency transfer function F at each of the times t1 to t n is calculated and for each of the times t1, t2, t3... t n an average value of the gains D' of the transfer function F is calculated, each with a frequency equal to or less than a predetermined value. The predetermined time period is a time period for the calculation unit for the height of the center of mass 202 to determine the load capacities P L , P R required to obtain the height of the center of mass with a given accuracy.

[0065] The calculation unit for the height of the center of mass 202 compares the read permissible range with the values for each of the times t1, t2, t3... t ncalculated average values of the gains D' of the frequency transfer function F and records average values each having a value within the permissible range among the average values of the gains D' of the frequency transfer function F corresponding to the times t1, t2, t3... t n The calculation unit for the height of the center of mass 202 averages the recorded average values over the times t1 to t n to calculate an average value over the time points t1 to t n to calculate (step S103).

[0066] Furthermore, the mass measuring unit 124 measures the mass m sm of the vehicle 1 (step S9), wherein the center of mass height calculation unit 202 calculates the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 is calculated according to equation (14) (step S104). [Effects of the second embodiment]

[0067] Since, according to the present embodiment, the calculation unit for the height of the center of mass 202 calculates the height h sm from the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 by means of the gain D' of the frequency transfer function F, the reduction in accuracy in calculating the height of the center of mass Q, which results from the phase difference between lateral acceleration G y and rolling moment M x can be prevented.

[0068] According to the present embodiment, the center of mass height calculation unit 202 divides the gain D' of the transfer function F with a frequency equal to or less than a predetermined value among the gains D' of the frequency transfer function F by the mass m sm of the spring-loaded part 5, so as to adjust the height h smfrom the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5. For this reason, in a case where the roll moment M x affected by noise due to the unevenness of the road surface, removes the high-frequency component of the gain D' which is susceptible to noise, and calculates the height of the center of mass Q with the low-frequency component of the gain D', so that the height of the center of mass Q can be calculated with higher accuracy.

[0069] In the present embodiment, an example has been described in which the transfer function calculation unit 201 calculates the frequency transfer function of the rolling moment M x on the lateral acceleration G ycalculated using the average periodogram method. However, the present disclosure is not limited thereto. For example, the transfer function calculation unit 201 may calculate the frequency transfer function using an autoregressive moving average (ARMA) model. In this case, for the lateral acceleration G y and the rolling moment M x each a power spectrum of the lateral acceleration G y and a power spectrum of the rolling moment M x obtained using the autoregressive moving average model. Furthermore, the gain D' of the frequency transfer function of the rolling moment M x with respect to the lateral acceleration G y using the power spectrum of lateral acceleration G y and the performance spectrum of the rolling moment M x be obtained.

[0070] In the present embodiment, an example has been described in which the center of mass height calculation unit 202 further calculates an average value over the times t1 to t n for statistics each having a value within the permissible range, among the statistics of the gain D' of the for each of the times t1, t2, t3... t n calculated frequency transfer function F and divide the average value by the mass m sm of the sprung part 5. However, the present disclosure is not limited to the configuration in which the average value of the statistics of the gain D' over the times t1 to t n For example, the calculation unit for the height of the center of mass 202 can be the height h smfrom the roll center RC of the vehicle 1 to the center of mass Q of the sprung part 5 by taking any one of the statistics of the gain D' of the for each of the times t1 to t n calculated frequency transfer function F by the mass m sm of the spring-loaded part 5. The height h sm from the roll center RC of the vehicle 1 to the center of gravity Q of the sprung part 5 can be calculated more accurately using the statistics of the gain D' of the frequency transfer function F.

[0071] Although the present disclosure has been described using the first and second embodiments, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various modifications and improvements can be made to the above-described embodiments. It is also clear from the description of the scope of the claims that an embodiment with such modifications or improvements can be included within the technical scope of the present disclosure.

[0072] This application is based on Japanese patent application JP 2018 - 177 070 A filed on April 17, 2017, the contents of which are incorporated herein by reference. Industrial applicability

[0073] The center of mass height estimator of the present disclosure is useful for estimating the height of a center of mass in a vehicle such as a commercial vehicle. List of reference numbers 1 vehicle 2 unsprung part 3L left rear wheel 3R right rear wheel 4L 4R air suspension 5 spring-loaded part 6 load 10 Estimator for the height of the center of mass 11 Storage unit 12 Control unit 20 Estimator for the height of the center of mass 121 Load capacity measuring unit 122 Roll moment calculation unit 123 Lateral acceleration measuring unit 124 Mass measurement unit 125 Calculation unit for the height of the center of mass 126 Calculation unit for the height of the center of mass above the ground 201 Transfer function settlement unit 202 Calculation unit for the height of the center of mass

Claims

[1] Estimation device (10, 20) for the height of the centre of mass, comprising: a roll moment calculation unit (122) configured to calculate the roll moment of a sprung part in a vehicle (1) based on the load capacities of left and right suspensions provided on the vehicle (1); a lateral acceleration measuring unit (123) configured to measure lateral acceleration, which is an acceleration in a width direction of the vehicle (1); a mass measuring unit (124) configured to measure the mass of the sprung member; a transfer function calculation unit (201) configured to calculate a transfer function of the roll moment with respect to the lateral acceleration; and a center of mass height calculation unit (125, 126, 202) configured to divide a gain of the transfer function by the mass of the sprung part to calculate a height from a roll center of the vehicle (1) to a center of mass of the sprung part, characterized by , that the center of mass height calculation unit (125, 126, 202) divides a transfer function gain corresponding to a frequency equal to or less than a predetermined value among the transfer function gains by the mass of the sprung part to calculate the height from the roll center of the vehicle (1) to the center of mass of the sprung part. [2] The height of the center of gravity estimating device (10, 20) according to claim 1, wherein the height of the center of gravity calculating unit (125, 126, 202) divides a statistic obtained from a plurality of gains of the transfer function corresponding to a frequency equal to or less than the predetermined value by the mass of the sprung part to calculate the height from the roll center of the vehicle (1) to the center of gravity of the sprung part. [3] Estimating device (10, 20) for the height of the center of mass according to one of claims 1 or 2, where each of the left and right suspensions is an air suspension (4L 4R) and the roll moment calculation unit (122) calculates the roll moment based on a difference between displacements of the left and right suspensions and a difference between pressures in the left and right suspensions.

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