JP4211861B2 - Vehicle roll angle estimation method and apparatus - Google Patents

Description

  The present invention relates to a vehicle roll angle estimation method and apparatus, and more particularly to a roll angle estimation method and apparatus suitable for use in an apparatus for determining a rollover risk of a vehicle (hereinafter referred to as a rollover risk determination apparatus). It is.

  A conventional example of the rollover risk determination apparatus as described above will be described below with reference to FIGS.

Conventional example: Figs. 8 to 10
The rollover risk determination device 10 shown in FIG. 8 includes a roll angle / roll angular velocity detection unit 11 that detects the roll angle φ and roll angular velocity ω of the vehicle, and the rollover risk of the vehicle based on the roll angle φ and roll angular velocity ω. A rollover risk determination unit 12 that determines H and calculates a target deceleration G _target from the rollover risk H, and a brake controller 13 that performs brake control according to the target deceleration _Gtarget . .

  Note that, as shown by the dotted line in the figure, the rollover risk determination device 10 outputs the rollover risk degree H to the outside and the rollover risk degree H is replaced with the brake controller 13 described above. It is also possible to provide an alarm device (not shown) that performs alarm control according to the above. In this case as well, the following description applies similarly.

  In operation, as shown in FIG. 9, first, the roll angle / roll angular velocity detection unit 11 detects the roll angle φ and the roll angular velocity ω of the vehicle and gives them to the rollover risk determination unit 12 (step S1).

  Next, the rollover risk determination unit 12 uses a two-dimensional map indicating the relationship between the roll angle φ and the roll angular velocity ω as shown in FIG. 10 and stored in advance in the two-dimensional map. Distances L1 and L2 from each of the boundary lines T1 and T2 to the point S specified by the roll angle φ and the roll angular velocity ω are calculated according to the following equations (1) and (2) (step S2). Here, the boundary lines T1 and T2 are a stable region R1 indicating that there is no risk of the vehicle rolling over, a left rollover risk region R2L indicating that there is a risk of the vehicle rolling over to the left, and a rollover to the right. The right rollover danger area R2R indicating that there is a risk of being struck.

  However, as shown in FIG. 10, A1 and B1 in the above equation (1) are the φ axis intercept and ω axis intercept of the boundary line T1, and A2 and B2 in the above equation (2) are the boundary line T2. φ-axis intercept and ω-axis intercept.

  Here, assuming that the left rollover risk area R2L side and the right rollover risk area R2R side are positive with respect to the boundary lines T1 and T2, and in each case, the stable area R1 side is defined as negative, the distances L1 and L2 The combinations are as follows.

 (A) When L1 ≦ 0 and L2 ≦ 0, there is no risk of rollover.

 (B) If L1> 0 and L2 ≦ 0, there is a risk of rollover to the left.

 (C) When L1 ≦ 0 and L2> 0, there is a risk of rollover to the right.

 (D) System error if L1> 0 and L2> 0.

  Therefore, when the above (A) is established (step S3), the rollover risk determination unit 12 determines that there is no risk of rollover (within the safety region R1) and does not perform any control (step S6).

  On the other hand, when the above (B) is established (step S4), the rollover risk determination unit 12 determines that there is a risk of left rollover (within the left rollover risk area R2L), and sets the distance L1 as the rollover risk H. (Step S7).

  If (C) is satisfied (step S5), the rollover risk determination unit 12 determines that there is a risk of right rollover (within the right rollover risk area R2R), and sets the distance L2 as the rollover risk H. (Step S8).

  As described above, when there is a risk of left rollover, the distance L1 is used as the value of the rollover risk degree H as it is.

Then, the rollover risk determination unit 12 calculates a target deceleration G _target necessary for preventing the vehicle from rolling over from the rollover risk H, and provides the target deceleration G _target to the brake controller 13 (step S9). The target deceleration G _target is not limited to the one calculated by multiplying the rollover risk degree H by the coefficient K as shown in the figure, but may be any one that changes according to the increase or decrease of the rollover risk degree H.

The brake controller 13 performs a brake control by calculating a brake pressure necessary for each wheel so that the target deceleration G _target is obtained (step S10).

  If (D) is established, the rollover risk degree determination unit 12 determines that the system error has occurred, and records an error flag in the rollover risk degree determination device 10 (step S11).

  In this way, it is possible to determine the rollover risk based on the roll angle and roll angular velocity that continuously change according to the running state of the vehicle, and to perform brake control, alarm control, etc. according to the rollover risk, This makes it possible to prevent the vehicle from rolling over (see, for example, Patent Application 2006-099281 by the applicant of the present application).

  In the above conventional example, the risk of rollover is determined based on the roll angle and roll angular velocity of the vehicle, but the vehicle height adjustment function that forcibly adjusts (corrects) the vehicle height on the left and right as in an air suspension equipped vehicle, etc. In the vehicle equipped with, there was a problem that the risk of rollover could not be correctly determined.

  Hereinafter, this problem will be specifically described with reference to FIG. 11 and FIG.

First, assuming that the vehicle is in the horizontal state SA1 when traveling straight as shown in FIG. 11, the loads F _L 0 and F _R 0 due to the vehicle body 2 with respect to suspensions (not shown) mounted near the left wheel 3L and the right wheel 3R, respectively. Since the road surface reaction forces W _L 0 and W _R 0 for the left wheel 3L and the right wheel 3R are equal to each other, there is no risk of rollover. Further, the left and right suspensions are not displaced from the reference position Z0.

When the vehicle turns right from the horizontal state SA1 to the left roll state SB1 shown in the figure, as shown in the figure, the load on the left suspension increases and F _L 1 (> F _L 0) On the other hand, the load on the right suspension is reduced to F _R 1 (<F _R 0). Correspondingly, the road surface reaction force on the left wheel 3L increases to W _L 1 (> W _L 0), and the road surface reaction force on the right wheel 3R decreases to W _R 1 (> W _R 0). That is, the left roll state SB1 indicates that the risk that the vehicle rolls over to the left is higher than that in the horizontal state SA1. Further, with the load variation, the left and right suspension has changed respectively from the reference position Z0 to the displacement Z _L and Z _R.

When the vehicle suddenly turns from the left roll state SB1 to the sudden turn state SB2 shown in the figure, the load on the left suspension further increases as shown in the figure, and F _L 1 _Roll (> F _L 1 ), And the load on the right suspension is further reduced to F _R 1 _Roll (<F _R 1). When the load F _R 1 _Roll finally becomes “0” and the corresponding road surface reaction force W _R 1 _Roll becomes “0”, the vehicle rolls over to the left.

On the other hand, in a vehicle having a vehicle height adjustment function, each suspension is returned to the reference position Z0 in order to correct the difference between the left and right vehicle heights caused by the left and right suspension displacements Z _L and Z _R in the left roll state SB1. As a result, the vehicle body 2 is again in the horizontal state SC1, as shown in FIG.

However, the load on the left and right suspensions hardly changes as shown below between the left roll state SB1 before the vehicle height adjustment and the horizontal state SC1 after the vehicle height adjustment (that is, “load F _L 2≈F _L 1”). and to "load F _R 2 ≒ F _R 1" is satisfied), to which corresponds "road surface reaction force W _L 2 ≒ W _L 1" and "road surface reaction force W _R 2 ≒ W _R 1" is satisfied . That is, the risk of vehicle rollover does not change before and after the vehicle height adjustment.

  This is the risk of rollover in the sudden turn state SB2, and the risk of rollover when the vehicle makes a sudden turn similar to the state between SB1 and SB2 from the horizontal state SC1 to the sudden turn state SC2 shown in the figure. The same applies to the relationship. That is, since the same roll motion occurs in the vehicle body 2 with the states SB1 and SC1 having the same rollover risk as the initial state, the rollover risks in the states SB2 and SC2 are equal to each other.

  The following demonstrates that the load on the left and right suspensions does not change before and after the vehicle height adjustment.

  First, the following formula (3) is established from the balance of forces in the vertical direction in the left roll state SB1 and the horizontal state SA1 before the vehicle height adjustment.

Here, when the load change ΔF is defined as in the following equation (4), the loads F _L 1 and F _R 1 in the left roll state SB1 are expressed by the following equation (5).

Further, when the roll angle in the left roll state SB1 is φ _SB1 (about 10 degrees even at the rollover limit, which is a sufficiently small value) as shown in FIG. 12, the roll center CR is the center. The balanced roll moment is expressed by the following equation (6).

However, m, h, a, g, and trd in the above formula (6) are respectively the mass of the vehicle body 2, the distance between the center of gravity CG and the roll center CR, the centrifugal acceleration, the gravitational acceleration, and the left and right as shown in the figure. The distance between suspensions. Note that “−F _L 1” and “+ F _R 1” in the above formula (6) represent the reaction force (not shown) of the left and right suspensions against the vehicle body 2.

  When the above equation (5) is substituted into the above equation (6) and rearranged, the load change ΔF can be expressed by the following equation (7).

Here, in the above equation (7), since φ _SB1 is a sufficiently small value, “a >> gφ _SB1 ” is established, so the load change ΔF is more influenced by the centrifugal force than the roll angle φ _SB1. It can be seen that it is caused by receiving much larger.

Accordingly, the loads F _L 2 and F _R 2 in the horizontal state SC1 after the vehicle height adjustment (the roll angle is substantially “0”) are the loads F _L 1 and F _L in the left roll state SB1 before the vehicle height adjustment, respectively. Will be approximately equal to _R1 .

By the way, the distances L1 _SB1 and L1 _SC1 in the left roll state SB1 and the horizontal state SC1 calculated by the equation (1) used in the conventional example are as shown in the following equations (8) and (9), respectively. Become.

  However, in the above equations (8) and (9), a common value ω is used as each roll angular velocity in the left roll state SB1 and the horizontal state SC1. This is because even if the vehicle height is adjusted, the turning state of the vehicle is not changed, and the same roll is used in the process of the vehicle transitioning from the left roll state SB1 and the horizontal state SC1 to the sudden turn state SB2 and SC2, respectively. This is to exhibit characteristics.

When the following equation (10) is obtained from the above equations (8) and (9), it can be seen that “distance L1 _SC1 <distance L1 _SB1 ” holds.

  Therefore, in the above conventional example, the rollover risk after adjusting the vehicle height is calculated as a lower value even though the vehicle rollover risk does not change before and after the vehicle height adjustment. Even in the sudden turning states SB2 and SC2 with the same risk of rollover, the risk of rollover in the state SC2 is erroneously determined to be lower than the risk of rollover in the state SB2.

  Even when a load is loaded on the vehicle body 2 when the vehicle is stopped, the vehicle is in the same state as the left roll state SB1, and the vehicle height difference caused by this is corrected by the vehicle height adjustment. Therefore, the risk of rollover is erroneously determined as described above.

  In order to deal with these, it is necessary to use the roll angle before the vehicle height adjustment as a parameter for determining the risk of rollover.

  Accordingly, an object of the present invention is to provide a method and apparatus capable of estimating the roll angle before the vehicle height adjustment.

 [1] In order to achieve the above object, a vehicle roll angle estimation method according to the present invention includes a plurality of preliminarily obtained internal pressure values indicated by left and right suspensions having the same displacement characteristics with respect to a load as parameters. A first step of selecting a displacement characteristic of an internal pressure value corresponding to an average value between the internal pressure values of both suspensions after adjusting the vehicle height as a displacement characteristic of each suspension before adjusting the vehicle height, among the displacement characteristics, and the vehicle height adjustment A second step of calculating a load on each suspension from the internal pressure value of each subsequent suspension, and calculating a displacement of each suspension before adjusting the vehicle height from the selected displacement characteristics and the calculated load, before adjusting the vehicle height. And a third step for obtaining the roll angle.

  That is, as shown in the above equation (3), the sum of the loads on both suspensions is constant (the balance of force in the vertical direction), and the load on each suspension is proportional to the internal pressure value exhibited by each suspension. Focusing on the relationship, the average value between the internal pressure values of the two suspensions after the vehicle height adjustment corresponds to the internal pressure values of the two suspensions that are equal to each other when the vehicle body is in a horizontal state before the vehicle height adjustment. For this reason, in the first step, the internal pressure corresponding to the average value between the internal pressure values of both suspensions after adjusting the vehicle height, among the displacement characteristics common to each suspension with respect to the load determined in advance for each internal pressure value indicated by each suspension. The displacement characteristic of the value is regarded as the displacement characteristic of each suspension before the vehicle height adjustment.

  Also, as explained using Equation (7) above, since the load on the left and right suspensions does not change before and after the vehicle height adjustment, each load calculated in the second step is regarded as the load on each suspension before the vehicle height adjustment. Can be tricked.

  In the third step, the displacement is calculated using the displacement characteristics and load of each suspension before the vehicle height adjustment, and the roll angle before the vehicle height adjustment is estimated from each calculated displacement.

  As a result, the roll angle before the vehicle height adjustment can be used in a rollover risk determination device or the like as in the conventional example.

 [2] In addition, in the above [1], the first step shows a displacement characteristic corresponding to a value obtained by further averaging the internal pressure average value of each suspension within a certain period immediately after the vehicle height adjustment before the vehicle height adjustment. And a step of selecting a displacement characteristic of each suspension, and the second step may include a step of calculating a load on each suspension from each internal pressure average value.

  In other words, since the internal pressure value of each suspension may not be stable immediately after the vehicle height adjustment, the first step corresponds to a value obtained by further averaging the average internal pressure value of each suspension within a certain period immediately after the vehicle height adjustment. The displacement characteristic to be selected is selected as the displacement characteristic of each suspension before the vehicle height adjustment, and the second step calculates the load on each suspension before the vehicle height adjustment from each internal pressure average value.

  Thereby, the roll angle before the vehicle height adjustment can be estimated more accurately.

 [3] In the above [1], at least a fourth step of detecting a roll angle immediately after the vehicle height adjustment, and a roll angle within a predetermined short period after the vehicle height adjustment from the roll angle before the vehicle height adjustment. May be further provided with a fifth step of obtaining a correction roll angle by the vehicle height adjustment.

  That is, the estimated roll angle is obtained by assuming that the vehicle body is in a horizontal state by the vehicle height adjustment (that is, the roll angle is “0”). It may be different from the actually corrected (lost) roll angle.

  However, the corrected roll angle by the vehicle height adjustment is accurately obtained by subtracting the actual roll angle within the predetermined short period after the vehicle height adjustment from the estimated roll angle, and this is used as a rollover risk determination device or the like. Can be used.

 [4] In the above [3], the fourth step includes a step of detecting a roll angle after the vehicle height adjustment, and the correction roll angle is added to the roll angle after the predetermined short period. A step of obtaining a roll angle that may occur in the vehicle when the vehicle height adjustment is not performed may be further provided.

  That is, in this case, since the roll angle to be detected when the vehicle height adjustment is not performed can be directly output, the influence of the change / improvement on the rollover risk determination device or the like can be minimized. it can.

In the present invention, it is possible to provide a program for causing a computer to execute the steps shown in the above [1] to [ 4 ] and a computer-readable recording medium on which the program is recorded.

[ 5 ] In addition, the vehicle roll angle estimation apparatus according to the present invention obtains in advance, as parameters, pressure detection means for detecting the internal pressure of the left and right suspensions having the same displacement characteristics with respect to the load, and the internal pressure value indicated by each suspension. Among the plurality of displacement characteristics, the displacement characteristic of the internal pressure value corresponding to the average value between the internal pressure values of both suspensions after the vehicle height adjustment is selected as the displacement characteristic of each suspension before the vehicle height adjustment, and the vehicle height adjustment A process of calculating a load on each suspension from each subsequent internal pressure value, calculating a displacement of each suspension before adjusting the vehicle height from the selected displacement characteristics and the calculated load, and obtaining a roll angle before adjusting the vehicle height Means.

  That is, a roll angle estimation device for a vehicle is provided that includes processing means for performing the same processing as the first to third steps described in [1] above for the internal pressure of each suspension detected by the pressure detection means. be able to.

[ 6 ] In addition, in the above [ 5 ], the processing means obtains a displacement characteristic corresponding to a value obtained by further averaging the internal pressure average value of each suspension within a certain period immediately after the vehicle height adjustment, before the vehicle height adjustment. Means for selecting the displacement characteristics of each suspension and means for calculating a load on each suspension from each internal pressure average value may be included.

[7] Also, in the above-mentioned [5], and a roll angle detecting unit for detecting a roll angle of at least immediately after該車height adjustment, the roll angle before該車height adjustment within a predetermined short period after該車height adjustment roll You may make it further provide the correction | amendment roll angle calculation means which calculates | requires the correction | amendment roll angle by this vehicle height adjustment by subtracting an angle.

[ 8 ] In addition, in the above [ 7 ], when the roll angle detection unit detects a roll angle after the vehicle height adjustment, the correction roll angle is added to the roll angle after the predetermined period. A means for obtaining a roll angle that may occur in the vehicle when vehicle height adjustment is not performed may be further provided.

That is, as shown in [ 6 ] to [ 8 ] above, to provide a vehicle roll angle estimation device including or having means for performing the same processing as the steps described in [2] to [ 4 ] above Can do.

  According to the present invention, the roll angle before the vehicle height adjustment can be estimated, and therefore even if a rollover risk degree judging device or the like using this is mounted on a vehicle having a vehicle height adjustment function, The risk of rollover can be determined accurately. As a result, vehicle rollover prevention control (brake control, alarm control, etc.) can be performed correctly, and the same effect can be obtained when the roll generated due to the load being biased left and right when the vehicle stops is corrected by adjusting the vehicle height There is.

  Embodiments of a vehicle roll angle estimation method and an apparatus using the same according to the present invention will be described below with reference to FIGS.

[1] Configuration example: Fig. 1 and Fig. 2
A vehicle roll angle estimation device 20 according to the embodiment of the present invention shown in FIG. 1 includes a pressure detection unit 21L that detects internal pressures PL and PR of suspensions 4L and 4R provided near the left wheel 3L and the right wheel 3R of the vehicle 1, respectively. and the 21R, when receiving the vehicle height adjustment end signal SG _F, with estimates the roll angle before based vehicle height adjustment pressure PL and PR, detected roll angle using the roll angle before the vehicle height adjustment estimated φ And a processing unit 22 that outputs the corrected roll angle φ _AMD .

This roll angle estimation device 20 is interconnected with the rollover risk determination device 10 similar to that in FIG. 8, and the detected roll angle φ is input from the roll angle / roll angular velocity detection unit 11, and the corrected roll angle φ _AMD is rolled over. This is output to the risk determination unit 12.

Further, the vehicle height adjusting device 30 includes vehicle height detectors 31L and 31R that detect left and right vehicle height displacements of the vehicle 1 as signals SG _L and SG _R , respectively, and suspension 4L based on the vehicle height displacement signals SG _L and SG _R. And a vehicle height adjusting unit 32 for adjusting the vehicle height by forcibly changing the displacement characteristics of the suspensions 4L and 4R by temporarily increasing or decreasing the internal pressure of 4R (injecting or discharging air AP), respectively. I have.

Here, the operation principle of the vehicle height adjusting device 30 is as follows.
・Operational principle of vehicle height adjustment device 30: Fig. 2
First, as indicated by the solid line in FIG. 2, when the vehicle 1 is at the vehicle height adjusting preceding horizontal state SA1 shown in FIG. 11, the suspension 4L and 4R together exhibit characteristics CF ₀ load F versus displacement Z. At this time, since the loads F _L 0 and F _R 0 for the suspensions 4L and 4R are equal to each other, the displacements of the suspensions 4L and 4R are “0” (reference position Z0) (point Q0).

Thereafter, when the vehicle 1 transitions to the left roll state SB1 shown in FIG. 11, the loads on the suspensions 4L and 4R become F _L 1 (> F _L 0) and F _R 1 (<F _R 0). In this process, the vehicle height adjusting unit 32 in the vehicle height adjusting device 30 does not execute any control, and the displacement characteristics = CF ₀ of the suspensions 4L and 4R are maintained. Therefore, the suspension 4L and 4R varies along the displacement characteristic CF ₀ from the reference position Z0 to the respective displacement Z _L (point QL1) and displacement Z _R (point QR1).

On the other hand, in order to correct the vehicle height difference caused by the displacements Z _L and Z _R , the vehicle height adjusting unit 32 injects air AP into the suspension 4L and temporarily pressurizes it, and the suspension 4L as shown by the dotted line in FIG. displacement characteristic of the varying from CF ₀ to CF _L. At the same time, the vehicle height adjusting unit 32 is temporarily reduced pressure by discharging air AP from the suspension 4R, varying the displacement characteristic of the suspension 4R as indicated by one-dot chain lines in FIG. 2 from CF ₀ to CF _R.

As described above, no load change before and after the vehicle height adjustment _{( "F L 2 ≒ F L} 1" and _{"F R 2 ≒ F R 1} " is satisfied.) Therefore, the suspension 4L is along the displacement characteristics CF _L returning to the reference from the displacement Z _L (point QL1) Te position Z0 (the point QL2), suspension 4R returns to displacement characteristic CF displaced along the _R Z _R (point QR1) from the reference position Z0 (the point QR2). As a result, the vehicle 1 changes to the horizontal state SC1 shown in FIG.

  The roll angle estimation device 20 estimates the roll angle before the vehicle height adjustment using the operation principle of the vehicle height adjustment device 30 described above.

That is, first, as will be described later with reference to FIG. 4, the processing unit 22 in the roll angle estimation device 20 uses the loads F _L 2 and F from the internal pressures PL and PR of the suspensions 4L and 4R in the horizontal state SC1 after the vehicle height adjustment. _R 2 (that is, loads F _L 1 and F _R 1 before the vehicle height adjustment) is calculated.

Based on the internal pressures PL and PR, the processing unit 22 selects a common displacement characteristic CF ₀ for the suspensions 4L and 4R from among a plurality of displacement characteristic candidates obtained in advance by experiments or the like.

Thereafter, the processing unit 22 identifies the points QL1 and QR1 on the displacement characteristic CF ₀ corresponding to the loads F _L 1 and F _R 1 to determine the displacements Z _R and Z _L of the suspensions 4L and 4R in the left roll state SB1. And the roll angle in the state SB1 can be obtained from these displacements Z _R and Z _L.

[2] Example of operation: Fig. 3 to Fig. 7
FIG. 3 shows the mutual operation of the rollover risk degree judging device 10 and the roll angle estimating device 20. As shown in the figure, a roll angle correction process (step S12) by the roll angle estimation apparatus 20 is newly added to the operation flow shown in FIG. Correspondingly, instead of the process of step S2 in the conventional example shown in FIG. 9, the rollover risk determination device 10 uses the corrected roll angle φ _AMD obtained by the roll angle correction process to use the distance L1 And step S2a for calculating L2.

  Thereby, even when the vehicle height adjustment is performed, the rollover risk degree determination device 10 can accurately determine the rollover risk degree H of the vehicle 1.

  The other processes in FIG. 3 (steps S3 to S11) are the same as those in FIG.

Hereinafter, the roll angle correction processing in step S12 will be specifically described with reference to FIGS.
◎ Example of roll angle correction processing: Fig. 4 to Fig. 7
Roll angle correction processing is broadly divided into (1) processing before vehicle height adjustment and (2) processing after vehicle height adjustment. The processing (2) is, (A) a process of estimating a vehicle height adjustment before the roll angle phi _E, (B) the roll angle is corrected by the vehicle height adjustment (hereinafter, the correction roll angle) calculation of phi _ros And (C) the above-described correction roll angle φ _AMD calculation process.

  Hereinafter, these processes will be described in order.

(1) Processing before vehicle height adjustment: Steps S20 to S23 in FIG.
As shown in FIG. 4, the processing unit 22 constituting the roll angle estimation device 20 adjusts the vehicle height every time it receives the detected roll angle φ from the roll angle / roll angular velocity detection unit 11 in the rollover risk determination device 10. is equal to or has been completed (i.e., whether it has received a vehicle height adjustment end signal SG _F from the vehicle height adjusting unit 32 of the level control system 30) (step S20).

When determining that the vehicle height adjustment has not ended, the processing unit 22 sets the correction end flag FLG to “OFF” (step S21), and initializes the correction roll angle φ _ros to “0” (step S21). S22). Here, the flag FLG indicates whether or not a correction roll angle φ _ros calculation process (B) described later has been executed, and is set to “ON” after the correction roll angle φ _ros is calculated. .

Then, the processing unit 22 obtains the corrected roll angle φ _AMD according to the following equation (11), and gives it to the rollover risk determination unit 12 in the rollover risk determination device 10 (step S23). However, since the corrected roll angle φ _ros = “0”, the corrected roll angle φ _AMD is equal to the detected roll angle φ.

  Thus, before the vehicle height adjustment, the detected roll angle φ is given to the rollover risk determination unit 12 as it is, as in steps S1 and S2 of FIG.

(2) Processing after vehicle height adjustment: Steps S24 to S38 and S23 in FIG. 4 and FIGS. 5 to 7
(A) Roll angle estimation process before vehicle height adjustment: Steps S24 to S34 in FIG. 4 and FIGS. 5 to 7
When it is determined in step S20 that the vehicle height adjustment has been completed, the processing unit 22 determines whether or not the correction end flag FLG is “OFF” (step S24).

  Since the correction end flag FLG = “OFF” is now established, the processing unit 22 further determines that the internal pressures PL and PR of the suspensions 4L and 4R and the number of samplings n of the detected roll angle φ have exceeded a predetermined threshold number Th. It is determined whether or not (step S25). Here, it is desirable to set the threshold number Th to a number sufficient to avoid sampling only the internal pressures PL and PR and the detected roll angle φ in an unstable state immediately after the vehicle height adjustment.

When it is determined that the sampling count n does not exceed the threshold count Th, the processing unit 22 calculates the internal pressure cumulative values PL _SUM and PR _SUM of the suspensions 4L and 4R and the cumulative value φ _SUM of the detected roll angle φ by the following formula: Calculation is performed according to (12) and equation (13) (steps S26 and S27).

However, the initial values of the cumulative values PL _SUM , PR _SUM , and φ _SUM are all “0”.

  Then, after incrementing the sampling count n by “1”, the processing unit 22 waits for the next internal pressures PL and PR and the roll angle φ to be input (step S28).

  Thereafter, the processing unit 22 repeatedly executes the above steps S26 to S28 until the sampling count n exceeds the threshold count Th. That is, the processing unit 22 does not perform any output to the rollover risk determination unit 12 until a certain period has passed immediately after the vehicle height adjustment.

As described above, the roll angle φ _E before the vehicle height adjustment is not estimated only from the internal pressures PL and PR in the unstable state immediately after the vehicle height adjustment, thereby preventing the erroneous determination in the rollover risk determination unit 12.

On the other hand, when it is determined in step S25 that the sampling count n has exceeded the threshold count Th, the processing unit 22 determines that the internal pressures of the suspensions 4L and 4R from the internal pressure cumulative values PL _SUM and PR _SUM according to the following equation (14): Average values PL _AVG and PR _AVG are respectively calculated (step S29).

Further, as shown in the following equation (15), the processing unit 22 further averages the internal pressure average values PL _AVG and PR _AVG to obtain an average value P _LR between the internal pressure values of both suspensions 4L and 4R (step S30). ).

Here, the average value P _LR between the internal pressure values calculated by the above equation (15) is the internal pressure value of the suspensions 4L and 4R (equal to each other) when the vehicle 1 is in the horizontal state SA1 shown in FIG. ).

Then, the processing unit 22, among the common plurality of displacement characteristics to the suspension 4L and 4L, executes a process of selecting the displacement characteristic corresponding to the internal pressure mean value P _LR calculated in step S30 above. This corresponds to the process of selecting the displacement characteristics CF ₀ before the vehicle height adjustment shown in FIG.

Here, the displacement characteristics as selection candidates are obtained in advance by experiments or the like as shown in FIG. 5, for example. That is, in the experimental stage, the internal pressure P is first made constant (that is, the internal pressure P is set to P ₁ [MPa], P ₂ [MPa],..., P ₇ [MPa] (P ₁ <P ₂ <... <P ₇ ), The load F applied to the suspension 4 is sequentially changed, and the displacement Z at each time is measured. As a result, actual displacement characteristics CF1 to CF7 indicated by dotted lines in FIG.

  After that, as shown by the solid line in Fig. 1 (1), the displacement characteristics CF1 to CF7 are linearly approximated, and the linear approximation expression EXP1 (load F = first order coefficient a1 · displacement Z + constant b1), EXP2 (F = a2・ Z + b2), EXP3 (F = a3 ・ Z + b3), EXP4 (F = a4 ・ Z + b4), EXP5 (F = a5 ・ Z + b5), EXP6 (F = a6 ・ Z + b6), EXP7 (F = a7 ・ Z + b7) . Although the displacement characteristic is linearly approximated here, it may be nonlinearly approximated by a quadratic expression or the like.

  The table shown in FIG. 2 (2) shows the internal pressure P and primary coefficients a1 to a7 (hereinafter referred to as symbol a) in the above-mentioned linear approximation expressions EXP1 to EXP7 (hereinafter sometimes collectively referred to as symbol EXP). And the values of constants b1 to b7 (hereinafter, sometimes collectively referred to as “b”) are described in association with each other. As shown in the figure, the first order coefficient a and the constant b are proportional to the internal pressure P. 6 (1) and (2) are plotted on the graph, and the first order coefficient a and the constant b are expressed by the following expressions (16) and (17).

Accordingly, the processing unit 22 calculates the first order coefficient a and the constant b from the average value _PLR between the internal pressure values obtained in step S30 using the above formulas (16) and (17). Then, the displacement characteristics of the suspensions 4L and 4R before the vehicle height adjustment are selected (step S31).

The processing unit 22 in accordance with the following equation (18), calculates a load F _L and F _R for suspension 4L and 4R from the calculated pressure average value PL _AVG and PR _AVG at step S29 above (step S32).

Here, the above equation (18) is a linear approximation equation (k and j are coefficients determined by design conditions etc.) indicating the characteristics between the load F and the internal pressure P exhibited by the suspensions 4L and 4R itself, and FIG. as shown, the load F _L and F _R from pressure PL _AVG and PR _AVG is uniquely identified, respectively.

Then, the processing unit 22, the above linear coefficient a and the constant b calculated in step S31, and the load F _L and F _R calculated in step S32 described above, according to the following formula (19), height adjustment before The displacements Z _L and Z _R of the suspensions 4L and 4R are calculated (step S33).

This identifies the load _{F L 2 (≒ F L 1} ) and _{F R 2 (≒ F R 1} ) points QL1 and QR1 on displacement characteristics CF ₀ with that shown in FIG. 2, the displacement Te than Z _L And Z _R. However, the above expression (19) is a comprehensive representation of the linear approximation expression EXP with respect to the displacements Z _L and Z _R using a _I and b _I defined in the following expression (20). .

Then, the processing unit 22 calculates the vehicle-adjustment roll angle φ _E from the displacements Z _L and Z _R calculated in step S33 according to the following equation (21) (step S34).

  However, trd in the above equation (21) is the distance between the suspensions 4L-4R.

  In this way, the roll angle before the vehicle height adjustment can be estimated based on the internal pressure of the left and right suspensions.

(B) Correction roll angle calculation processing: Steps S35 to S38 in FIG.
After the above process (A), the processing unit 22, according to the following formula (22), and calculates the detected roll angle mean value phi _AVG from the roll angle cumulative value phi _SUM calculated in step S27 above (step S35) .

Then, the processing unit 22 calculates a corrected roll angle φ _ros from the vehicle height pre-adjustment roll angle φ _E according to the following equation (23) (step S36).

Since the calculation of the correction roll angle φ _ros based on the internal pressures PL and PR and the detected roll angle φ for the sampling number n has been completed, the processing unit 22 performs the sampling number n, the internal pressure cumulative values PL _SUM and PR _SUM , and the roll angle cumulative value. All _φSUM are set to “0” and initialized (step S37), and the correction end flag FLG is set to “ON” (step S38).

(C) Correction roll angle calculation process: Step S23 in FIG.
After the processing (B), the processing unit 22 calculates the corrected roll angle φ _AMD by adding the corrected roll angle φ _ros calculated in step S36 to the detected roll angle φ, and the rollover risk determination unit (Step S23 and equation (11)).

Thereafter, since the correction end flag FLG = “ON” is established, the processing through the above steps S20, S24, and S23 is repeatedly executed, and the post-correction roll angle φ _AMD is sequentially given to the rollover risk determination unit 12. It becomes.

  As a result, the rollover risk determination unit 12 can accurately determine the rollover risk H as in the case where the vehicle height adjustment is not performed.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that various modifications can be made by those skilled in the art based on the description of the scope of claims.

That is, in the above embodiment, the case where the roll angle estimation device 20 calculates the corrected roll angle φ _AMD and causes the rollover risk determination device 10 to use the vehicle height calculated in the above processing (A). The roll angle before adjustment φ _E or the corrected roll angle φ _ros calculated in the above process (B) may be used by the rollover risk determination device 10.

It is the block diagram which showed the Example of the roll angle estimation method and apparatus of a vehicle which concerns on this invention, and its usage example. It is the graph which showed the operation principle of the vehicle height adjustment apparatus used for the Example of the roll angle estimation method and apparatus of the vehicle which concerns on this invention. It is the flowchart figure which showed the example of mutual operation | movement with the rollover risk degree determination apparatus used for the Example of the roll angle estimation method and apparatus of a vehicle concerning this invention. It is the flowchart figure which showed the roll angle correction process example in the Example of the roll angle estimation method and apparatus of the vehicle which concerns on this invention. It is the figure which showed the example of the suspension displacement characteristic used for the Example of the roll angle estimation method and apparatus of the vehicle which concerns on this invention. It is the graph which showed the relationship between the internal pressure average value of the suspension used for the Example of the roll angle estimation method and apparatus of a vehicle concerning this invention, and a displacement characteristic coefficient. It is the graph which showed the internal pressure-load characteristic used for the Example of the roll angle estimation method and apparatus of a vehicle concerning this invention. It is the block diagram which showed the structural example of the conventional vehicle rollover risk degree determination apparatus. It is the flowchart figure which showed the operation example of the conventional vehicle rollover risk determination apparatus. It is the graph which showed the two-dimensional map used for the conventional vehicle rollover risk determination apparatus. It is the block diagram which showed the running state of the vehicle provided with the vehicle height adjustment function. It is the block diagram which showed the balance of the roll moment in the vehicle in turning driving | running | working.

Explanation of symbols

1 Vehicle
2 Body
3L left wheel
3R right wheel
4L, 4R suspension
10 Rollover risk assessment device
11 Roll angle / roll angular velocity detector
12 Rollover risk assessment section
13 Brake controller
20 Roll angle estimation device
21L, 21R Pressure detector
30 Vehicle height adjustment device
31L, 31R Height detector
32 Height adjustment section φ Detection roll angle ω Roll angular velocity φ _W Roll angle before height adjustment φ _ros correction roll angle φ _AMD correction roll angle φ _AVG roll angle average value
SG _F Vehicle height adjustment end signal
PL, PR Internal pressure
PL _AVG , PR _AVG Internal pressure average value
Average value between P _LR internal pressure values
CF suspension displacement characteristics
EXP linear approximation
a, b coefficients
F _L , F _R load
Z _L , Z _R displacement
Z0 reference position In the figure, the same reference numerals indicate the same or corresponding parts.

Claims (10)

Internal pressure corresponding to the average value between the internal pressure values of both suspensions after adjustment of the vehicle height, out of a plurality of displacement characteristics obtained in advance using the internal pressure values indicated by the left and right suspensions having the same displacement characteristics with respect to the load as parameters. A first step of selecting a displacement characteristic of the value as a displacement characteristic of each suspension before the vehicle height adjustment;
A second step of calculating a load on each suspension from the internal pressure value of each suspension after the vehicle height adjustment;
A third step of calculating a displacement of each suspension before the vehicle height adjustment from the selected displacement characteristic and the calculated load to obtain a roll angle before the vehicle height adjustment;
A roll angle estimation method for a vehicle, comprising: In claim 1,
The first step of selecting a displacement characteristic corresponding to a value obtained by further averaging the average internal pressure value of each suspension within a certain period immediately after the vehicle height adjustment as a displacement characteristic of each suspension before the vehicle height adjustment. Including
The method for estimating a roll angle of a vehicle, wherein the second step includes a step of calculating a load on each suspension from each internal pressure average value. In claim 1,
A fourth step of detecting at least a roll angle immediately after the vehicle height adjustment;
A fifth step of obtaining a corrected roll angle by the vehicle height adjustment by subtracting a roll angle within a predetermined short period after the vehicle height adjustment from the roll angle before the vehicle height adjustment;
A roll angle estimation method for a vehicle, further comprising: In claim 3,
The fourth step includes a step of detecting a roll angle after the vehicle height adjustment,
A vehicle further comprising a step of obtaining a roll angle that can occur in the vehicle when the vehicle height adjustment is not performed by adding the corrected roll angle to the roll angle after the predetermined short period. Roll angle estimation method. The program for making a computer perform each step of the method as described in any one of Claim 1 to 4. A computer-readable recording medium on which the program according to claim 5 is recorded. Pressure detecting means for detecting the internal pressure of the left and right suspensions having the same displacement characteristics with respect to the load;
  Of the plurality of displacement characteristics obtained in advance using the internal pressure value indicated by each suspension as a parameter, the displacement characteristics of the internal pressure value corresponding to the average value between the internal pressure values of both suspensions after the adjustment of the vehicle height are the suspension characteristics before the vehicle height adjustment. And calculating the load on each suspension from each internal pressure value after the vehicle height adjustment, and calculating the displacement of each suspension before the vehicle height adjustment from the selected displacement characteristic and the calculated load. Processing means for determining a roll angle before the vehicle height adjustment;
  An apparatus for estimating a roll angle of a vehicle. In claim 7,
The processing means is
Means for selecting, as a displacement characteristic of each suspension before the vehicle height adjustment, a displacement characteristic corresponding to a value obtained by further averaging the average value of the internal pressure of each suspension within a predetermined period immediately after the vehicle height adjustment;
Means for calculating the load on each suspension from each internal pressure average value;
A roll angle estimation device for a vehicle characterized by comprising: In claim 7 ,
A roll angle detection unit for detecting at least the roll angle immediately after the vehicle height adjustment;
A correction roll angle calculation means for calculating a correction roll angle by the vehicle height adjustment by subtracting a roll angle within a predetermined short period after the vehicle height adjustment from the roll angle before the vehicle height adjustment;
An apparatus for estimating a roll angle of a vehicle , further comprising: In claim 9 ,
The roll angle detection unit detects a roll angle after the vehicle height adjustment,
A vehicle further comprising means for obtaining a roll angle that can occur in the vehicle when the vehicle height adjustment is not performed by adding the corrected roll angle to the roll angle after the predetermined short period. Roll angle estimation device.

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