JPH07119610B2 - Direction display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an azimuth display device that displays the traveling direction of a vehicle or the like based on geomagnetism, and particularly the traveling direction frequently changes near the boundary of the azimuth display area. Even so, it relates to an azimuth display device capable of preventing display flicker without impairing the response speed.

[Prior Art] FIG. 6 is a block diagram showing a conventional azimuth display device described in, for example, JP-A-59-99309. In the figure, (1) is a geomagnetic sensor provided on a moving object such as a vehicle, which independently detects two geomagnetic components corresponding to the front and rear and left and right of the vehicle body, and separates them as electric signals e _x and e _y , respectively. Is being output. (2) is an amplifier circuit that amplifies the electric signals e _x and e _y and outputs the DC electric signals V _x and V _y .

(3) is the DC electrical signal V _x output from the amplifier circuit (2)
And V _y for appropriately delaying them and absorbing frequent fluctuations of the respective DC electric signals V _x and V _y .

(6) is an azimuth determination circuit that determines the azimuth based on the output signals X and Y delayed by the delay circuit (3), and (8) has a plurality of azimuth display areas P _{1 to} P ₈ indicating the traveling direction. It is an indicator. The azimuth display areas P _{1 to} P ₈ are east, northeast,
…, Southeast respectively.

Since the conventional azimuth display device is configured as described above, for example, when the vehicle travels in a place where the magnetic environment is bad, such as an elevated road where seams made of iron are exposed, it is output from the geomagnetic sensor (1). Even if the electric signals e _x and e _y fluctuate little by little, if the delay time of the delay circuit (3) is set appropriately, the fluctuation of each electric signal e _x and e _y is absorbed, and the azimuth display area P ₁ ~P ₈ will not be frequently flickers.

[Problems to be Solved by the Invention] As described above, the conventional azimuth display device delays the DC electrical signals V _x and V _y based on the geomagnetism and uses them for the azimuth display. However, if the delay time is reduced and the delay time is decreased, the display flickers when the traveling direction changes near the boundary of the azimuth display area.

The present invention has been made to solve the above problems. A predetermined angle hysteresis is provided centering on the boundary of the azimuth display area, and the traveling vector turns into a boundary vector (corresponding to the azimuth display area. It is an object of the present invention to provide an azimuth display device in which the flicker of the display is prevented without impairing the response speed by making the angle hysteresis effective in the case where the azimuth is frequently passed in different directions. Further, when the traveling vector passes through the boundary vector in the same direction, it is another object to obtain an azimuth display device in which the angle hysteresis is invalidated and the accuracy of the display angle is prioritized.

[Means for Solving Problems] An azimuth display device according to the present invention includes an azimuth detector mounted on a traveling object to detect a traveling azimuth of the traveling object, and a plane formed by each azimuth boundary vector. A direction determination based on a display having a plurality of azimuth display areas divided by and a traveling azimuth vector corresponding to the traveling azimuth of a traveling object, and driving the display to display the azimuth on the display In the azimuth display device including a circuit, the azimuth determination circuit includes a turning direction memory that stores a turning direction when the traveling azimuth vector passes the boundary vector, and when the traveling azimuth vector turns and passes the boundary vector. When the previous turning direction stored in the turning direction memory and the present turning direction do not match, a predetermined amount of angle hysteresis is provided to determine the azimuth and display the indicator. When it is driven and the previous turning direction and the present turning direction match, the azimuth is determined and the display is driven without setting the angle hysteresis.

[Operation] In the present invention, even if the electric signal corresponding to the traveling direction frequently fluctuates near the boundary of the azimuth display area, the azimuth display area is not changed until the angle hysteresis is exceeded.
Further, when the electric signal corresponding to the traveling direction passes through the boundary of the azimuth display area in the same direction, the angle hysteresis is invalidated and the accuracy of the display angle is prioritized.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing position vectors (hereinafter referred to as boundary vectors) A _{1 to} A ₈ with respect to boundary coordinates, and FIG. 3 is a digital coordinate signal representing a traveling direction. Is an explanatory view showing a position (advancing direction) vector (hereinafter referred to as an advancing vector) Q with respect to, and FIG.

In FIG. 1, (6A) corresponds to the azimuth determination circuit (6), and (1), (2) and (8) are the same as those described above. (4) is a sensitivity correction circuit for associating (normalizing) the electric signals e _x and e _y with the coordinates on the first circle, for example, the circle C (see FIG. 3) having a predetermined radius A, The DC electrical signals V _x and V _y from the amplifier circuit (2) are multiplied by an appropriate coefficient to obtain (V _x ′) ² + (V _y ′) ² = A ² satisfying electrical signals V _x ′ and V _y ′. It is designed to be converted.

(5) is an AD conversion circuit for converting the electric signals V _x ′ and V _y ′ whose sensitivity has been corrected into digital coordinate signals x and y. The digital coordinate signals x and y represent the traveling direction of the vehicle, and as shown in FIG. 3, in the orthogonal coordinate plane XY whose origin O is 1/2 of the binary full scale of the AD conversion circuit (5), It is represented by a point on the circumference C of a predetermined radius A centered on the origin O, and the traveling vector for this point (x, y) is Q.
In FIG. 3, the vertical axis X corresponds to the digital coordinate signal x proportional to the north-south direction component of the geomagnetic sensor (1), and the horizontal axis Y corresponds to the digital coordinate signal y proportional to the east-west direction component. .

(7) is a point (X ₁ , Y ₁ ) on the second circle (for example, the circle C having the predetermined radius A) that has a plurality of boundary coordinates corresponding to the boundaries of the azimuth display areas P _{1 to} P _8. ~ (X _8, Y ₈₎ a boundary memory for storing normalized (second see figure), these boundary coordinates (X _1, Y ₁₎ boundary vectors for ~ (X _8, Y ₈₎ is a ₁ ~ It is represented by A ₈ .

In FIG. 2, the boundary vector A ₁ is a vector rotated 22.5 ° counterclockwise from the X axis. Also, the other boundary vectors A _{2 to} A ₈ are sequentially arranged from the boundary vector A ₁ to 45, respectively.
It is a vector rotated by each degree, and its scalar amount (absolute value) is equal to 1/2 of the full scale of the AD conversion circuit (5), that is, the radius A of the circumference C.

(61) is an outer product arithmetic circuit that sequentially and repeatedly selects two adjacent boundary coordinates from the boundary memory (7) and calculates the outer product of the boundary vector and the progress vector Q for these boundary coordinates, and (62) is the outer product arithmetic circuit. A turning direction memory that temporarily stores the previous turning direction of the vehicle based on the selection direction of the boundary vector sequentially selected in (61), and (63) is the relationship between the previous turning direction and the present turning direction and two The azimuth display area output circuit determines the azimuth display area based on the smaller one of the outer products. That is, the turning direction memory (62) stores the turning direction when the traveling vector passes through the boundary vector as the previous turning direction.

The above (61) to (63) are provided in the azimuth determination circuit (6A), and the two boundary coordinates (X _N , Y _N ) and (X _{N + 1} , Y _{N +} ) that are adjacent and are sequentially selected are selected. ₁ ) and digital coordinate signal (x,
y) is compared with the fluctuation of the digital coordinate signal based on the fluctuation of the traveling direction with a predetermined amount of angle hysteresis,
A display area selecting means for selecting the azimuth display areas P _{1 to} P ₈ is configured. The angle hysteresis is determined by the predetermined value ε shown in FIG.

The operation of the embodiment of the present invention shown in FIGS. 1 to 4 will now be described with reference to the flowchart of FIG. 5 showing the operation of the azimuth determination circuit (6A).

First, when the power is turned on, initialization is performed in step (601). As a result, the outer product calculation circuit (61)
Selects the boundary coordinates (X ₁ , Y ₁ ) and (X ₈ , Y ₈ ) to be used for the first outer product operation from the boundary memory (7), and the boundary vector A ₁
And read A ₂ .

Next, in step (602), the advancing vector Q for the digital coordinate signals x and y is read from the AD conversion circuit (5), and in step (603), the two boundary vectors A ₁ and A ₂ already read are read. Of these, the coordinates (X ₂ , Y ₂ ) of the boundary vector A ₂ that advances in the counterclockwise direction are read.
In FIG. 5, two boundary vectors are generally A _N (X _N ,
Y _N ) and A _{N + 1} (X _{N + 1} , Y _{N + 1} ).

Next, in step (604), an outer product S ₁ of the boundary vector A ₂ traveling in the counterclockwise direction and the traveling vector Q is calculated. As shown in FIG. 3, the progress vector Q and the boundary vector
If the angles formed by A _{2 and the} X axis are θ ₁ and θ ₂ , respectively, the outer product S ₁ is S ₁ = A ₂ × Q = | A ₂ | · | Q | · sin (θ ₂ −θ ₁ ). It is represented by. Here, although it is not easy to find the angle θ ₁ formed between the traveling vector Q and the X axis, the boundary coordinates (X ₂ ,
Y ₂ ), and the digital coordinate signal (x, y) are on the same circumference C. When the formula is expanded, S ₁ = | A ₂ | ・ | Q | ・ (sin θ ₂ cos θ ₁ − sin θ ₁ cos θ ₂ ) = | A ₂ | · sin θ ₂ · | Q | · cos θ ₁ − | A ₂ | · cos θ ₂ · | Q | · sin θ ₁ = Y ₂ x−X ₂ y. That is, the outer product S ₁ is represented by the digital coordinate signal (x, y) and the boundary coordinate (X ₂ , Y ₂ ), and is represented by an equation that does not include the angles θ ₁ and θ ₂ . Generally, as shown in FIG. 5, the formula is S ₁ = Y _{N + 1} · x−X _{N + 1} · y.

Next, in step (605), the azimuth display area selection circuit (63) determines the polarity of the calculated outer product S ₁ . For example, as shown in FIG. 3, the progress vector Q is the azimuth display area P ₃
In the case of, the outer product S ₁ is negative because sin (θ ₂ −θ ₁ ) in the equation is negative. This indicates that the traveling vector Q of the digital coordinate signal (x, y) corresponding to the earth's magnetism is in a position near the counterclockwise direction with respect to the boundary vector A ₂ .

If it is determined that S ₁ ≦ 0 in step (605), step (61
0), and it is determined whether the previous turning direction is counterclockwise. If it is initially set to "counterclockwise" in step (601), the process proceeds to step (612) and the bearing display area P _N
To the azimuth display area P _{N + 1} moved one counterclockwise from. Then, the combination of the boundary vectors to be adopted at the time of the next display update is A ₂ and A ₃ which are moved one counterclockwise, and “counterclockwise” is stored as the previous turning direction in the turning direction memory (62).

In this way, the azimuth determination circuit (6A) drives the azimuth display area P ₃ of the display (8) for display, and waits at step (616) until the next display update time comes.

The above steps (602) to (612) can be processed in an extremely short time as compared with the speed at which the vehicle turns, so in step (612) the boundary vectors A ₂ and A ₃ are selected, and Even if the progress vector Q is read again in step (602) at the display update time, it does not significantly change from the previous progress vector Q. For example, step (61
Including the waiting time of 6), if the cycle of executing the repeating step (602) is set to 16 msec, it has sufficient display followability.

At the next display update time, the progress vector Q is read in step (602), and the boundary vector A is read in step (603).
_When the boundary coordinates (X ₃ , Y ₃ ) of ₃ are read and the outer product S ₁ is calculated in step (604), as is clear from FIG. 3, the progress vector Q is closer to the clockwise than the boundary vector A ₃ . The position.

Therefore, from the equation, the outer product S ₁ is positive, and the step (60
The procedure proceeds from step 5) to step (606), and the boundary coordinates (X ₂ , Y ₂ ) of the boundary vector A _{2 that has} returned by one clockwise is read. Then, in step (607), the outer product S ₂ of the boundary vector A ₂ and the progress vector Q is calculated from the equation. This cross product S
₂ , the progress vector Q is the boundary vector A ₂ as described above.
On the other hand, it is always counterclockwise, so it will always be negative.

Therefore, in step (608), it is determined that S ₂ <0, the process proceeds to step (609), and the previous azimuth display area P _N (= P ₃ ) corresponding to the value of N is driven to light.

That is, in the azimuth display area output circuit (63), the outer product S _{1 of the} boundary vector A ₃ that has advanced counterclockwise and the traveling vector Q of the two boundary vectors A ₂ and A ₃ that are the azimuth determination boundaries is positive, Boundary vector A ₂ and progression vector Q delayed clockwise
Since the outer product S ₂ of and becomes negative, it is determined that the traveling direction of the vehicle at this time is the azimuth display area P ₃ sandwiched by the boundary vectors A ₂ and A ₃ at an acute angle.

This determination is made by the fact that the cross product of two vectors, whose absolute values are each normalized, indicates whether one vector serving as a reference is closer to the other, clockwise or counterclockwise. That is, the latest traveling direction of the vehicle is determined by sequentially searching for boundary vectors that sandwich the normalized traveling vector Q at an angle narrower than the display resolution.

Next, the vehicle runs in a place where the magnetic environment is bad, and as shown in FIG. 4, the progress vector Q changes from time Q1 → Q2 →
A case will be described in which the distance fluctuates little by little with Q3 and the two azimuth display areas P ₁ and P ₂ are alternately moved.

Now, the progress vector Q originally in the bearing display area P _2
It is assumed that ₁ is displaced to the traveling vector Q ₂ in the azimuth display area P _{1 at} the next moment. At this time, the progress vector Q after displacement
_2, due to the clockwise position as viewed from the boundary vectors A ₁ and A _2, which was selected when it was in the first orientation the display region P _2, traveling vector Q ₂ for each boundary vectors A ₁ and A ₂
The outer products S ₁ and S _{2 of} are both positive. Therefore, step (60
In step 8), S ₂ ≧ 0 is determined, and the process proceeds to step (613).

Here, if the previous turning direction of the vehicle was clockwise, the process proceeds from step (613) to step (615), and the boundary vector for the traveling vector Q _{2 at the} next moment is:
A ₁ and A ₈ indicating the azimuth display area P ₁ that has moved one clockwise are selected, and the azimuth display area P _{1 of the} display (8) is driven to light. At the same time, the previous turning direction is stored in the turning direction memory (62) as right.

Further, at the next moment, it is assumed that the traveling vector Q ₂ is displaced counterclockwise to the traveling vector Q ₃ in the azimuth display area P ₁ . At this time, the outer product S ₁ calculated in step (604) is negative because the progress vector Q ₃ is closer to the left than the boundary vector A ₁ . Therefore, in step (605), S ₁ ≦ 0 is determined, and the process proceeds to step (610) to determine whether the previous turning direction is counterclockwise. Since the previous turning direction is stored as right, it is determined that the turning direction is different from the current turning direction, and the process proceeds to step (611). Then, the absolute value of the outer product S ₁ is compared with a preset value E.

Here, the predetermined value E is an expression including the angle hysteresis ε shown in FIG. 4, E = | A _N × Q _M | = | A _N | ・ | Q _M | ・ sin ε (where 0 ° ≦ ε ≦ 90 °), the absolute value of the outer product S ₁ of the boundary vector A ₁ and the progression vector Q ₃ is | S ₁ | ＝ | A ₁ × Q ₃ | ＝ | A _N × Q _M | ＝ | A _N | ・ | Q _M | ・ | sin θ ｜ ……. Therefore, the processing in step (611) is to compare the expressions. Here, since the boundary vector A _N and the traveling vector Q _M are both position vectors on the same circle C, each absolute value of the boundary vector A _N and the traveling vector Q _M is the radius A (constant) of the circle C. Comparing the equations and the magnitudes of the equations is comparing sin θ and sin ε. That is, the angle θ formed by the boundary vector A _N and the traveling vector Q _M may be compared with the angle hysteresis ε.

As shown in FIG. 4, if θ <ε, that is, if the absolute value | S ₁ | of the outer product S ₁ is | S ₁ | <E, then | S ₁ | ≦ E is determined in step (611). Then, the process proceeds to step (616) and holds the azimuth display area P ₁ indicating the previous traveling direction of the vehicle.

In the case of FIG. 4, the turning direction is changed from right to left, but when the turning direction is reversed from left to right, the same processing is performed by step (614).

In this way, the vehicle has made one or more turns past the boundaries of the azimuth display areas P _{1 to} P ₈ , and the digital coordinate signal (x, y) for reversing the turning direction by one boundary is input next. In this case, if the angle θ formed by the boundary vector A _N and the traveling vector Q _M exceeds a preset angle hysteresis ε (for example, 3 °), the orientation display area P where the traveling vector Q _M after inversion exists ₁ is set as the traveling direction of the vehicle, and if the angle hysteresis ε is not exceeded, the azimuth display area P _{j in} which the traveling vector Q _M-1 before reversal exists is processed as the traveling direction of the vehicle.

As a result, the azimuth display area output circuit (63) indicates that the previous turning direction and the present turning direction stored in the turning direction memory (62) are opposite to each other, and the absolute value of the _two outer products S ₁ and S _{2 is} the absolute value. If the smaller value of is smaller than the predetermined value E, the azimuth display area P _j is not moved. On the other hand, if it is determined in step (610) or step (613) that it is in the same direction as the previous turning direction (that is, YES), it is not related to the display flicker, so step (611) or (6
Skip step 14) to disable the angle hysteresis and improve the angle accuracy of the direction display.

In the above embodiment, the display (8) has eight azimuth display areas.
Although the case of having P _{1 to} P ₈ has been described, the same effect can be obtained even in the case of having an arbitrary number of azimuth display areas.

Further, although the first and second circles C for normalizing the progress vector Q and the boundary vectors A _{1 to} A ₈ are made to coincide with each other, the circles may have different radii.

Also, as an azimuth detector that detects the traveling azimuth of a traveling object,
Although the geomagnetic sensor (1) that detects the geomagnetic components in the two directions is used, another direction detector may be used as long as it can detect the traveling direction.

[Effects of the Invention] As described above, according to the present invention, an azimuth detector mounted on a traveling object to detect a traveling azimuth of the traveling object, and a plurality of planes formed by the respective azimuths are divided by a plurality of boundary vectors. And an azimuth determination circuit for driving the display to display the azimuth on the display while determining the azimuth based on the traveling azimuth vector corresponding to the traveling azimuth of the traveling object. In the azimuth display device, the azimuth determination circuit includes a turning direction memory that stores a turning direction when the traveling azimuth vector passes through the boundary vector,
When the traveling direction vector turns and passes through the boundary vector, if the previous turning direction stored in the turning direction memory and the current turning direction do not match, a certain amount of angle hysteresis is provided to determine the direction. In order to drive the display and match the previous turning direction with the current turning direction, the azimuth is judged and the display is driven without setting the angle hysteresis, so it is possible to prevent display flicker. ,
With respect to the turning direction irrelevant to the display flicker, it is possible to obtain the azimuth display device in which the angle accuracy of the azimuth display is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing normalized boundary coordinates, FIG. 3 is an explanatory diagram showing normalized digital coordinate signals, and FIG. FIG. 5 is an explanatory view showing the angle hysteresis, FIG. 5 is a flow chart for explaining the operation of one embodiment of the present invention, and FIG. 6 is a block diagram showing a conventional azimuth display device. (1) ...... Geomagnetic sensor, (4) ...... Sensitivity correction circuit (5) ...... AD conversion circuit, (6A) ...... Direction determination circuit (61) ...... Outer product calculation circuit, (62) ...... Turning direction memory (63) ... Direction display area output circuit (7) ... Boundary memory, (8) ... Display e _x , e _y , V _x ', V _y ' ... Electrical signal x, y ... Digital coordinate signal P _{1 to} P ₈ …… Direction display area A _{1 to} A ₈ …… Boundary vector Q, Q _{1 to} Q ₃ …… Progression vector S ₁ , S ₂ …… Outer product ε …… Hysteresis A …… Predetermined radius, C… ... Circumference In the drawings, the same reference numerals indicate the same or corresponding portions.

Claims (1)

[Claims] 1. An azimuth detector mounted on a traveling object to detect a traveling azimuth of the traveling object, and a display having a plurality of azimuth display areas in which a plane formed by each azimuth is divided by a plurality of boundary vectors. In an azimuth display device including an azimuth determination circuit that determines the azimuth based on a traveling azimuth vector corresponding to the traveling azimuth of the traveling object, and drives the display to display the azimuth on the display. The azimuth determination circuit includes a turning direction memory that stores a turning direction when the traveling direction vector passes the boundary vector, and when the traveling direction vector turns and passes the boundary vector, the turning direction When the previous turning direction stored in the memory and the present turning direction do not match, a predetermined amount of angle hysteresis is provided to determine the azimuth and the display is displayed. Driven, when the turning direction and the current turning direction of the previous match, azimuth display device and drives the indicator to determine the orientation without setting the angle hysteresis.