JPH0476611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an integral angle detection method that detects an angle by integrating an angular velocity signal from an angular velocity sensor.

[Problems to be solved by conventional technology and invention]

Such an integral angle detection method informs the current position of a moving object such as a vehicle by displaying the trajectory of the moving object overlaid on a map, and provides information for determining the subsequent direction of movement of the moving object. An example of its use can be seen in navigation devices.

The navigation device is generally configured as shown in FIG. The control processing circuit 3 calculates the position of the moving object after the movement based on the angle signal obtained by the integration and the position information of the moving object before the movement, and sequentially stores the calculated position in the memory. Based on the position information stored in the memory 4, the locus of movement of the moving object is drawn on the screen of a display device 5 such as a CRT. At this time, map information of the area where the moving object is currently located is selected from the memory 4 and displayed simultaneously on the display device 5 overlapping the movement trajectory. In addition, 6 in the figure is a keyboard, and in addition to selecting map information, there are keys used for performing operations such as aligning the current position of the mobile object on the map displayed on the display device 5. There is.

The principle by which the control processing circuit 3 detects an angle based on the angular velocity signal from the angular velocity sensor 2 is generally as follows.

Now, suppose that the moving object turns to the right in its direction of travel for a time t ₁ , then goes straight, and then turns to the left for a time t _2.The output of the angular velocity sensor 2 is an angular velocity signal f as shown in FIG. ₁ (T) and f ₂ (T) are generated. In order to detect the angle based on this angular velocity signal, the control processing circuit 3 calculates _{the areas} S ₁ and
Find S ₂ respectively. That is, the right turning angle A _R
and the left turning angle A _L are obtained by performing the calculations A _R = S ₁ = ∫ ^t1 ₀ f ₁ (T)dT A _L = S ₂ = ∫ ^t2 ₀ f ₂ (T)dT.

Although the output waveform of the angular velocity sensor 2 shown in FIG. 4 is depicted as an ideal waveform with no drift,
In reality, drift is superimposed on the output of the angular velocity sensor 2 due to various disturbances, and the angular velocity signal shown in FIG. 4 comes to be output in the form shown in FIG. 5, for example. Note that in FIG. 5, the output drift V ₀ (T) of the angular velocity sensor 2 is approximately shown by a straight line αT for simplicity.

When the angle is determined by integrating the angular velocity signal on which the drift is superimposed as shown in FIG. 5, the area of the dotted portion in the diagram becomes an error. That is,
The area S ₁ in Figure 4 becomes S ₁ ' in Figure 5,
The area with points up to the point where the waveform intersects with the 0 point is added as an error. On the other hand, the area S ₂ in FIG. 4 becomes S ₂ ' in FIG. 5, which is smaller by the area of the point surrounded by the output waveform and the drift curve.

Therefore, in the case of FIG. 5, the position calculated based on the angle signal and distance signal obtained as described above is to the right of the actual direction of travel. If this is repeated, as shown in Figure 6,
The movement trajectory A drawn by calculation quickly deviates from the predetermined tolerance range C defined around the actual movement trajectory B in a short time D. If this happens, if you do not immediately correct the movement trajectory A to the corresponding position on the map, the current position cannot be read from the movement trajectory drawn on the map. become unable to do so.

That is, if there is an output drift of the angular velocity sensor, it becomes necessary to perform alignment operations frequently, which is not very desirable in practice.

Although such problems can be solved to some extent by using a high-precision angular velocity sensor, a high-precision angular velocity sensor is very expensive and is a major obstacle to commercialization.

Therefore, the present invention aims to provide an integral angle detection method that can relatively accurately determine the angle even if the accuracy of the angular velocity sensor is not so good and even if drift is superimposed.

[Means and actions for solving problems]

In order to solve the above-mentioned problems, the angle detection method according to the present invention provides a judgment level with a constant width of positive and negative, and a point in time when the angular velocity signal falls within the judgment level from a certain period of time before the point when the angular velocity signal exceeds the judgment level. The angular velocity signal is integrated until after a certain period of time, and no integration is performed outside of this period.

As described above, the level of the angular velocity signal is judged based on the judgment level with a constant width of positive and negative, and the time when the judgment level is exceeded and the constant value before and after the time when the judgment level is exceeded and the time when the judgment level is entered are determined. Since the angular velocity signal is integrated only during the period including the time, and other periods are regarded as drift components and are not integrated, it is possible to reduce errors when calculating the angle.

〔Example〕

Embodiments of the integral angle detection method according to the present invention will be described below with reference to the drawings.

FIGS. 1a and 1b are diagrams for explaining an embodiment of the integral type angle detection method according to the present invention.

In FIG. 1a, f ₁ (T) and f ₂ (T) are angular velocity signals obtained from the output of the angular velocity sensor, and the signal f ₁
(T) and f ₂ (T) are drift components V ₀ (T) due to disturbances, etc.
= αT is included. +V _c and -V _c are predetermined voltage levels for level determination, and are used to determine whether the angular velocity signal exceeds the voltage level |V _c |.

Then, with reference to the voltage level |V _c |, the point in time when the angular velocity signals f ₁ (T) and f ₂ (T) exceed the level |V _c | and the point in time when they fall within the level |V _c | are determined, respectively. By detection, times t ₁ ′ and t ₂ ′ at which f ₁ (T) and f ₂ (T) exceed |V _c | are determined, respectively. After that _, the angular _velocity signals _{f 1 ( T )} and _{f 2} (T) to obtain areas S ₁ '' and S ₂ '' as shown in FIG. 1b, and these are detected as angles.

In Figure 1b, the area of the dotted area is the error, which becomes clear if you compare it with the error (area of the dotted area) of the conventional method shown in Figure 5. In addition, the angle detected by the method of the present invention has less error due to the influence of the output drift of the angular velocity sensor by the shaded area in the figure.

This is because signals that are equal to or less than |V _c | and that are not within time t _c are forcibly regarded as 0, and an angle with less error due to output drift can be detected.

Therefore, by enabling the angle detection method of the present invention described above to detect an angle with a small error, the navigation device can detect the angle shown in FIG.
It becomes possible to draw a movement trajectory E as shown by the dotted chain line. That is, it becomes possible to draw a movement locus within the predetermined range C without long-term correction, and the number of troublesome correction operations for position alignment can be reduced.

FIG. 2 is a block diagram showing an example of the configuration of an integral angle detection device that implements the method according to the present invention described above. The A/D converter 10 outputs an angular velocity signal obtained by sampling the angular velocity signal at an appropriate sampling frequency, quantizing it, and converting it into a digital signal. A shift register 11 sequentially receives the digitized angular velocity signal from the A/D converter 10, and the shift register 11 functions as a delay means for delaying the input angular velocity signal by a time _tc .

12 is a level setting unit that sets the voltage level |V _c | for determining the level of the angular velocity signal; 13 is the voltage level |V _c | inputted to one input, and the angular velocity signal from the angular velocity sensor 2 inputted to the other input. For example, it is a comparator consisting of a window comparator. The output of the comparator 13 is at H level when the angular velocity signal exceeds the voltage level |V _c |;
At other times, it is at L level. The output of comparator 13 is the set input S of R-S flip-flop 14.
It is also connected to the reset input R of the R-S flip-flop 14 via an inverter 15 and a delay circuit 16 with a delay time of _2tc .

17 is an integrator, and when the Q output of the flip-flop 14 is at H level, the shift register 1
Integration is performed by sequentially integrating the digitized angular velocity signals delayed by the time t _c from 1, and an angular signal is sent as the output.

With the above configuration, the angular velocity signal from the angular velocity sensor 2 is digitized by the A-D converter 10, inputted to the shift register 11, sequentially shifted within the shift register 11, and outputted after being delayed by a time _tc . Sent out. When the level of the angular velocity signal exceeds |V _c |, the output of the comparator 13 rises from the L level to the H level, thereby setting the R-S flip-flop 14, and its output Q changes from the L level to the H level. As a result, the integrator 17 starts integrating the digitized angular velocity signal from the shift register 11. The angular velocity signal integrated by the integrator 17 is the one obtained before time _tc .

On the other hand, when the angular velocity signal becomes smaller than |V _c |,
The output of the comparator 13 goes from H to L level, and the output of the inverter 15 goes from L to H level. In response to this, the output of the delay circuit 16 rises from L to H level after 2t _c time. As a result, the R-S flip-flop 14 is reset, its Q output changes from H to L level, and the integration operation of the integrator 17 is stopped. In other words, _the period of the angular velocity signal accumulated by the integrator 17 is from t c time before the angular velocity signal exceeds |V _c | to t _c time when the angular velocity signal becomes below |V _c |
Until hours later.

Note that in the above embodiment, the entire dotted area of the area S ₂ ″ is included as a drift error, but the polarity of the angular velocity at the time when |V _c | is exceeded and t _c at that time If the polarity of the angular velocity signal is different from that of the previous time, as shown by the dotted line in Figure 1b, if the angular velocity signal is shifted and integrated by the level of the previous time _tc , the drift error will be equal to this shift. can be made smaller.

〔effect〕

As described above, according to the present invention, components in the angular velocity signal that do not satisfy specific conditions are regarded as drift and are not integrated.
Angle detection with less drift error can now be performed, and when this is applied to a vehicle navigation device, it becomes possible to drive for a long time without correction using an inexpensive angular velocity sensor.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the principle of the integral angle detection method according to the present invention, FIG. 2 is a block diagram showing an example of a device for implementing the method of the present invention, and FIG. 3 is a vehicle navigation system. 4 is an explanatory diagram showing the general principle of the integral angle detection method, FIG. 5 is an explanatory diagram illustrating the problems of the conventional method, and FIG. 6 is an explanatory diagram showing the conventional method. It is an explanatory view explaining a problem of a navigation device using the method. 2...Angular velocity sensor, 12...Level setting section,
13...Comparator, 17...Integrator.

Claims (1)

[Scope of Claims] 1. In a method of detecting an angle by integrating an angular velocity signal from an angular velocity sensor, a determination level with a constant width of positive and negative is provided, and the angular velocity signal exceeds the determination level for a certain period of time. An integral type angular velocity detection method, characterized in that the angular velocity signal is integrated until a certain period of time after the angular velocity signal has entered a determination level, and no integration is performed outside the period.