JP2000028373A - Method for predicting shape of road and method for controlling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent error prediction on the shapes of roads due to errors in road map data. SOLUTION: In a method for predicting the shapes of roads, a link length LN and a crossed axes angle θN are computed on the basis of the coordinates of three nodes NN-1, N, and NN+1 selected from among a plurality of nodes constituting road map data, and the shape of a road is predicted by the amount of turning of a vehicle θN/LN obtained by dividing the cross axes angle θN by the link length LN. In this case, the amount of turning of the vehicle θN/LN corresponding to each node NN present in the same curve is equalized to compute the amount of turning of the vehicle θ/L, and the shape of the road is predicted on the basis of the equalized amount of turning of the vehicle θ/L. Even when errors are present in the individual amount of turning of the vehicle θN/LN due to errors in the road map data, it becomes possible to reduce the effects of the errors and to predict the overall shape of the road accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road shape prediction method for predicting a road shape based on map data comprising a set of a plurality of nodes, and a vehicle control method using the method.

[0002]

2. Description of the Related Art Such a road shape prediction method and a vehicle control method have already been proposed by the present applicant in Japanese Patent Application No. 9-89661. This uses the coordinates of a large number of nodes N _N (N _N = N ₀ , N ₁ , N ₂ , N ₃ ...) Set at predetermined intervals on the road as road map data, as shown in FIG. A link length L _N defined as a distance between adjacent nodes N _N and N _{N + 1,} and a certain link N _N-1 N _N
And a crossing angle θ _N defined as an angle between the node N _N and the link N _N N _{N + 1} located in front of the node N _N
Then, the passing state determination amount (vehicle turning amount) θ _N / L _N is calculated. Then a passable speed of the node N _N calculated based on the passing state determination amount θ _N / L _N, is compared with the estimated passage speed which the vehicle passes through the node N _N, it is determined that passing is difficult In the event of a warning, the driver is alerted or decelerated automatically. The passing state determination amount θ _N
/ L _N corresponds to the amount of change in the azimuth angle of the vehicle with respect to the travel distance of the vehicle. A large value indicates that the road is curved, and a small value indicates that the road is curved. Indicates a straight road.

[0003]

Meanwhile [0008] Since the coordinates of the node N _N constituting the road map data is inevitable to contain certain errors, sequentially node N _N is in constant radius of curvature of the curve even if present, in some cases the variation is generated in the passing state determination amount θ _N / L _N at each node N _N. In such a case, when an alarm or automatic deceleration based on the passing state determination amount θ _N / L _N at each node N _N, it is possible that they alarm or deceleration control discomfort to the driver become incoherent .

The present invention has been made in view of the above circumstances, and has as its object to prevent a road shape from being erroneously predicted due to an error in road map data.

[0005]

In order to achieve the above-mentioned object, the invention described in claim 1 is based on three of the positions of a plurality of nodes constituting road map data and the position of the own vehicle on the road. A position is selected, and an intersection angle formed by a link connecting the first and second positions and a link connecting the second and third positions among the three selected positions is at least between the second and third positions. In a road shape prediction method for predicting a road shape based on a link length, when a plurality of node positions exist on the same curve, a plurality of vehicle turning amounts are calculated based on the selected three positions, and the plurality of vehicle turning amounts are calculated. The road shape is predicted based on the average value or the sum of the vehicle turning amounts.

According to the above configuration, the vehicle turning amount is calculated for a plurality of nodes existing on the same curve, and the road shape is predicted based on the average value or the sum of the plurality of vehicle turning amounts. Even if an error occurs in the turning amount of each vehicle due to an error in the data, the influence of the error can be reduced and the overall road shape can be accurately predicted.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, when the ratio of the vehicle turning amount at two consecutive nodes is out of a predetermined range, the vehicle turning at the two nodes is performed. It is characterized in that the calculation of the average value or the sum of the amounts is stopped.

According to the above configuration, when the ratio of the vehicle turning amount at two consecutive nodes is out of the predetermined range, the calculation of the average value or the sum of the vehicle turning amounts at each node is stopped. If the radius of curvature of a road changes suddenly between two curves or in the middle of a curve,
It is possible to prevent the curvature radii from being meaninglessly averaged, and to correctly predict the actual road shape.

In the embodiment, the predetermined range is 1.6 <.
When A <2.0, the range is set as 1 / A to A, but the range is a design matter that can be changed as appropriate.

According to a third aspect of the present invention, there is provided a vehicle control method using the road shape predicting method according to the first or second aspect, wherein the vehicle can pass a road ahead. The driving state of the vehicle is controlled based on the predicted road shape.

According to the above configuration, since the road shape is accurately predicted by eliminating the error in the road map data, the driving state of the vehicle is controlled so that the vehicle can pass through the road having the predicted shape. It is possible to perform accurate vehicle control according to the shape and to reliably pass the road ahead.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a block diagram showing the entire configuration of a vehicle passability judging device, FIG. 2 is an explanatory diagram of a prefetch section and a search section,
FIG. 3 is a flowchart for explaining the operation, and FIG. 4 is an explanatory diagram of the reference node N, the link length L, and the intersection angle θ.

As shown in FIG. 1, the passability determination device mounted on the vehicle includes a map information output means M1, a vehicle position detection means M2, a curve section determination means M3, and a passage state determination amount calculation means M4. Passable speed calculating means M5, vehicle speed detecting means M6, predicted passing speed calculating means M7, passability determining means M8, and alarm means M as a vehicle control means.
9 and a vehicle speed adjusting means M10 as a vehicle control means. The curve section determination means M3 and the passing state determination amount calculation means M4 together constitute a road shape determination means M11.

The map information output means M1 and the vehicle position detection means M2 are mounted on a well-known automobile navigation system. The map information output means M1 includes an IC card, a CD-ROM, and a rewritable MO. (Magneto-optical disk) reads and outputs road map data in a predetermined range stored in advance, and the vehicle position detecting means M2 superimposes the vehicle position data received from the GPS antenna on the road map data and displays the road map data on the map. Of the own vehicle position P is detected.
The road map data is composed of the coordinates of a number of nodes N _N that are set at predetermined intervals on the road.

The curve section determining unit M3, based on the road map data and the vehicle position P, determines the forward node N _N of the vehicle position P is present or straight path exists on the curve. The passing state determination amount calculation means M4 calculates, for each curve, a passing state determination amount θ / L that is an index for determining whether the vehicle can pass the curve.

The passable speed judging means M5 is based on the pass state judging amount θ / L and a set limit lateral acceleration G (or a set limit yaw rate YR) preset so that the driver can safely pass through the curve. , The vehicle is node N
_Passable speed V which is the maximum vehicle speed that can safely pass _{N
Calculate maxN} .

The vehicle speed detecting means M6 detects the current vehicle speed V of the own vehicle based on the output of a wheel speed sensor provided for each wheel. Estimated passage speed calculating means M7 includes a vehicle speed V, the and the vehicle position P, based on the reference deceleration β of the vehicle which is set in advance to calculate the estimated passage speed V _N of the vehicle passes the node N _N. Passing determination means M8 determines, as compared to the passable speed V _maxN the predicted passing speed V _N, and if V _N ≦ V _maxN vehicle can pass through the node N _N. Also, V
If _N> V _maxN vehicle is determined to be difficult pass through the node N _N, actuates the warning means M9 consisting buzzer or a lamp to prompt deceleration of the vehicle to the driver, the automatic braking in order to automatically decelerate the vehicle The vehicle speed adjusting means M10 comprising means for shifting down the automatic transmission, or means for reducing the engine output, is operated.

As shown in FIG. 2, a look-ahead section and a search section are set on a road in front of the vehicle position P. In the pre-reading section, the own vehicle position P and a node N _{N for} determining whether or not the vehicle can pass are referred to.
It intended to be set between, ensuring a predetermined time t before the vehicle reaches node N _N through the pre-read interval,
Within this predetermined time t, it is determined whether or not the vehicle can pass, and the alarm means M9 and the vehicle speed adjusting means M10 are operated. Exploration period is for performing the determination of passability for the node N _N existing in the exploration period, is avoided to make decisions unnecessary passableness about this by far the far node N _N .

In the pre-reading section, a reference deceleration β which is presumed to be generated by the braking is preliminarily set when it is assumed that the driver has started braking spontaneously at the own vehicle position P so as to pass a curve ahead. The predetermined time t
Is determined by the distance the vehicle travels Vt- (βt ^2/2) within. The start end of the search section is set at the end of the prefetch section, and the end of the search section is set at the position where the vehicle decelerating at the reference deceleration β stops, that is, the position at a distance V ² / 2β from the vehicle position P.

Next, the operation of the embodiment of the present invention will be described with reference to the flowchart of FIG.

[0022] First, read the coordinates of a plurality of nodes N ... within exploration interval _{(N = N 1, N 2} , N 3 ...) at step S1, a plurality in the exploration in the interval in step S2 node N ... of selecting either the reference node N _N. Reference node N _N for all the nodes N in the exploration zone ..., it intended to be sequentially selected from the first node N ₁ to the next node N _2, for each of the selected criteria node N _N A determination is made as to whether or not the vehicle can pass.

As shown in FIG. 4, the the reference node N _N is selected at step S2, the coordinates of the reference node N _N in Step S3, 2 nodes adjacent to its front and rear N
Based on the _{N-1, N N + 1} of coordinate, calculates a link length L _N and crossing angle theta _N at the reference node N _N.

When the first node N ₁ in the search section is selected as the reference node N ₁ , the first node N ₀ behind the search section is selected as the adjacent node behind it. At this time, if the node N ₀ between the vehicle position P and the reference node N ₁ is not present, the vehicle position P is selected in place of the node N _0.

[0025] All the nodes N link length in _N L _N and crossing angle theta _N exploration in section this way is calculated, link length crossing angle theta _N for each of the nodes N _N in step S4 L _N To calculate the passing state determination amount (vehicle turning amount) θ _N / L _N.

In the following step S5, each node N_NPassing
State judgment amount θ_N/ L_NBy monitoring the same curve
Node N on top_NIs estimated. Specifically, no
De N _NPassing state determination amount θ_N/ L_N= S_NAnd next to it
Contacting node N_{N + 1}Passing state determination amount θ_{N + 1}/ L_{N + 1}=
S_{N + 1}Ratio S_{N + 1}/ S_NIs suddenly changing,
Presumed that the changed node is the entrance or exit of the curve
Nodes between the entrance and exit
Can be presumed to exist on the for that reason
, A reference value A (1.6 <A <2.0) is set in advance,
S_{N + 1}/ S_N> A, the difference from a straight road to a curve
S at the starting position_{N + 1}/ S_NIs determined to have increased rapidly
And S_{N + 1}/ S_NIf <1 / A holds, it is a curve
S at a position approaching a straight road_{N + 1}/ S_NAnd suddenly decreased
Can be determined. Also the intersection angle θ_NIs the sign
Node N in the middle of the same curve_NIntersection angle at
θ_NIs reversed, the node N_NBefore and after the car
Is determined to be an S-shaped curve in which the direction of the curve changes.
You. An S-shaped curve is considered as two curves with different directions of curvature.
The first and second half curves are separate
Processing is performed.

When the curve areas in the search section are determined as described above, the passing state determination amount (vehicle turning amount) θ / L averaged in each curve area in step S6.
Is calculated. There are four types of methods for calculating the averaged passing state determination amount θ / L described below.

First Method When N nodes N _{1 to} N _N exist on the same curve,
The passing state determination amount S ₁ (= N) of a total of N nodes N _{1 to} N _N
θ ₁ / L ₁ ), S ₂ (θ ₂ / L ₂ )... _SN (= θ _N / L
_N ) are added, and the sum S ₁ + S ₂ +... + S _N is divided by N to calculate the averaged passing state determination amount θ / L.

Second Method When N nodes N _{1 to} N _N exist on the same curve,
Passage state determination amounts S ₁ ... S of a total of N nodes N _{1 to} N _N
Of the _N , first and second passing state determination amounts S ₁ ,
The average value of S ₂ (S ₁ + S ₂ ) / 2 = Sa is calculated, and then the average value (Sa + S ₃ ) / 2 = Sb of the average value Sa and the third passing state determination amount S ₃ is calculated. , followed by the average value Sb and the average value of the fourth passing state determination amount S ₄ (Sb +
S ₄ ) / 2 = S _C is calculated, and this is repeated N−1 times up to the N-th passage state determination amount _SN to calculate the averaged passage state determination amount θ / L.

Third Method When N nodes N _{1 to} N _N exist on the same curve,
From the 0th and 1st link lengths L ₀ , L ₁ and the intersection angle θ ₁ , the first passing state determination amount S ₁ is calculated as S ₁ = θ ₁ / (L _0/2)
Calculated in + L _1/2), first and second link length L _1, L ₂ and crossing angle theta ₂ Metropolitan from the second passing state determination amount S
₂ was calculated by _{S 2 = θ 2 / (L} 1/2 + L 2/2), a passing state determination amount S _N of the N in the same manner S _N = theta _N /
It is calculated by (L _N-1 / 2 + L _N / 2). The sum of the _N passing state determination amounts S ₁ ... _SN is S ₁ + S ₂ +.
Passing state determination amount θ / L averaged by dividing _SN by N
Is calculated.

[0031]Fourth method N nodes N on the same curve₁~ N_NIf exists,
N intersection angles θ₁~ Θ _NAddition value of Σθ_NN links
Length L₁~ L_NAddition value of L_NAnd the quotient Σθ_N/
ΣL_NCalculates the averaged passing state determination amount θ / L as
I do.

[0032] Incidentally, the node yaw rate YR of the vehicle in the N _N is the crossing angle θ is a variation in the traveling direction of the vehicle
The _N, it is divided by the time taken to generate t theta _N
/ T. Since the time t is given by L _N / V obtained by dividing the link length L _N by the vehicle speed V passing therethrough, the yaw rate YR finally becomes the passing state determination amount θ _N /
It is calculated by the product of _LN and vehicle speed V.

[0033]

(Equation 1)

On the other hand, the lateral acceleration G of the vehicle is the yaw rate YR
And the vehicle speed V.

[0035]

(Equation 2)

In step S7, from the above equations (1) and (2),

[0037]

(Equation 3)

Is calculated. Equation (3) determines the set limit lateral acceleration G allowed when the vehicle passes through a curve, and sets the set limit lateral acceleration G and the passing state determination amount θ _N /
Based on the L _N, the vehicle indicates that the passable speed V _maxN when passing through the curve is obtained. The passable speed V _maxN is the maximum vehicle speed at which the lateral acceleration of the vehicle can pass through the curve without _{exceeding the} set limit lateral acceleration G.

At this time, in this embodiment, each node N
_NPassing state determination amount θ_N/ L _NDon't use
And each node N on the same curve_NAveraging the above
The passing state determination amount θ / L is used. As a result, the road
The specific node N is determined by the error_NCommunication in
Overstate determination amount θ_N/ L_NHas a value far from others
But the warning and automatic deceleration described later are executed
This prevents the driver from feeling uncomfortable. Only
Also, as described above, the adjacent node N_N, N_{N + 1}Passing
State determination amount S_{N + 1}/ S_NIs the predetermined value A or the predetermined value
1 / A, that is, adjacent node N_N, N_{N + 1}
Is not on the same curve,
Determination amount S_N, S_{N + 1}Averaging is stopped.
Node N that does not exist on the node_N, N_{N + 1}Passing status judgment
Quantity S_N, S_{N + 1}Ensures that no meaningless averaging occurs
Can be done.

On the other hand, in step S8, the vehicle is estimated passage speed V _N passing through the node N _N assuming that the decelerated at the reference deceleration β from the vehicle position P is, from the vehicle position P to the node N _N Let S _{N be} the distance of

[0041]

(Equation 4)

Is calculated by

The subsequent comparison of the predicted passing speed V _N and passable velocity V _maxN in step S9, if V _N ≦ V _maxN vehicle is determined to be passing through the node _N N, V N> V _maxN
If judged that the vehicle is difficult passes through the node N _N. If the vehicle is difficult passes through the node N _N is actuates the warning means M9 to prompt deceleration of the vehicle to the driver in step S10, activating the vehicle speed adjusting means M10 so as to automatically decelerate the vehicle. As a result, the driver's spontaneous braking and automatic deceleration are performed, and the vehicle speed decreases,
The vehicle can pass the curve without fail.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the passable speed V _maxN is calculated based on the set limit lateral acceleration G. However, the passable speed V _maxN is calculated based on the set limit yaw rate YR instead of the set limit lateral acceleration G. It is also possible. That is, from the equation (1), the passable speed V _maxN is _calculated as

[0046]

(Equation 5)

May be calculated as follows.

[0048]

As described above, according to the first aspect of the present invention, the vehicle turning amount is calculated for a plurality of nodes existing on the same curve, and the average or the sum of the plurality of vehicle turning amounts is calculated. Since the road shape is predicted based on the
Even if an error occurs in each vehicle turning amount due to an error in the road map data, the influence of the error can be reduced and the overall road shape can be accurately predicted.

According to the second aspect of the present invention,
When the ratio of the vehicle turning amounts at two consecutive nodes is out of the predetermined range, the calculation of the average value or the sum of the vehicle turning amounts at each node is stopped. Therefore, between two discontinuous curves or in the middle of a curve. Thus, when the radius of curvature of the road suddenly changes, the radius of curvature is prevented from being meaninglessly averaged, and the actual road shape can be correctly predicted.

According to the invention described in claim 3,
After accurately predicting the road shape by eliminating errors in the road map data, the driving state of the vehicle is controlled so that the vehicle can pass through the road with the predicted shape, so accurate vehicle control according to the road shape is performed. It is possible to reliably pass the road ahead.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a device for determining whether or not a vehicle can pass;

FIG. 2 is an explanatory diagram of a prefetch section and a search section.

FIG. 3 is a flowchart illustrating an operation.

FIG. 4 is an explanatory diagram of a reference node N, a link length L, and an intersection angle θ.

[Explanation of symbols]

 L Link length N Node P Own vehicle position θ Crossing angle θ / L Vehicle turning amount

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yuji Sakaki 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 2F029 AA02 AB13 AC09 AC14 5H180 AA01 BB04 BB12 BB13 CC12 FF04 FF21 LL02 LL07 LL08 LL09 LL15

Claims (3)

[Claims] 1. A method for selecting three positions among a plurality of nodes constituting the road map data and a vehicle position on a road, and connecting the first and second positions among the three selected positions. A road shape prediction method for predicting a road shape based on an intersection angle (θ) formed by a link and a link connecting the second and third positions, and at least a link length (L) between the second and third positions. When there are a plurality of node positions on the same curve, a plurality of vehicle turning amounts (θ /
L), and predicting the road shape based on the average or the sum of the plurality of vehicle turning amounts (θ / L). 2. When the ratio of the vehicle turning amount (θ / L) at two consecutive nodes is out of a predetermined range, the average value or the sum of the vehicle turning amount (θ / L) at the two nodes is calculated. 2. The road shape prediction method according to claim 1, wherein the road shape is stopped. 3. A vehicle control method using the road shape prediction method according to claim 1 or 2, based on the predicted road shape so that a vehicle can pass a road ahead. A vehicle control method comprising controlling a driving state of a vehicle.