JPS6378019A - Integral type angle detecting method - Google Patents

Abstract

PURPOSE:To execute an angle detection for scarcely causing a drift error, by executing an integration extending from before a prescribed time of the time point when an angular velocity signal exceeds a decision level, to after a prescribed time of the time point when said signal has entered within the decision level, and executing no integration in other period than said period. CONSTITUTION:A shift register 11 operates as a delay means for delaying by a time (tc) portion an angular velocity signal from an angular velocity sensor 2, which has been inputted through an A/D converter 10. A level setting part 12 sets a voltage level ¦Vc¦, and to a comparator 13, the voltage level ¦Vc¦ and the angular velocity signal are inputted, respectively. An output of the comparator 13 becomes an H level and an L level, when the angular velocity signal exceeds the voltage level ¦Vc¦, and at other time, respectively, connected to a set input S of an FF 14, and also, connected to a reset input R of the FF 14 through an inverter 15 and a delaying circuit 16 of a delay time 2tc. When a Q output of the FF 14 is at an H level, an integrator 17 executes an integration by integrating successively the digitized angular velocity signal which has been delayed by the time (tc), from the shift register 11, and sends out an angle signal to its output.

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 the prior art and the invention] Such an integral angle detection method informs the current position of a moving object such as a vehicle by superimposing its movement trajectory on a map, and then An example of its use can be found in navigation devices that provide information for determining the direction of movement of a mobile object.

A navigation device is generally configured as shown in FIG. 3, in which a distance signal from a distance sensor 1 mounted on a moving object and an angular velocity signal from an angular velocity sensor 2 also mounted on a moving object are integrated in a control processing circuit 3. The control processing circuit 3 calculates the position of the moving body after the movement based on the angle signal obtained from the angle signal and the position information before the movement of the moving body, and sequentially stores the calculated position in the memory. Based on the positional information stored in 4, the locus of movement of the moving body 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, the display device 5
Keys are provided that are used to perform operations such as aligning the current position of the mobile object on the map displayed on the map.

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 briefly as follows.

Now, the moving object changes its direction of movement at time 1. Assuming that the angular velocity sensor 2 makes a right turn for a while and then goes straight, and then makes an open turn at a time t2, the angular velocity sensor 2 outputs an angular velocity signal f+ as shown in FIG.
('r) and f2 (T) are generated. In order to detect the angle based on this angular velocity signal, the control processing circuit 3 calculates the areas S and S of the angular velocity signals B (T) and fz (T).
Find each of 2. That is, the right turning angle AR and the left turning angle A are obtained by performing the following calculations.

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

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 S1 in FIG. 4 becomes SI' in FIG. 5, and the area to which the waveform intersects the zero point is added as an error. On the other hand, the area S2 in FIG. 4 becomes 82' in FIG. 5, which is smaller by the area of the point surrounded by the output waveform and the Drift 1-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 will quickly deviate from the predetermined tolerance range C defined around the actual movement trajectory B in a short period of time. become. If this happens, if you do not immediately correct the drawn movement trajectory A to the corresponding position on the map, the current position will be read from the movement trajectory drawn on the map. I won't be able to do that.

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 eliminated to some extent by using a high-precision angular velocity sensor, a high-precision angular velocity sensor is very expensive and becomes a major bottleneck in 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 operations for solving the problem] In order to solve the above problem, the angle detection method according to the present invention provides a judgment level with a constant range of positive and negative, and detects the point at which the angular velocity signal exceeds the judgment level. The angular velocity signal is integrated from a predetermined time period until a predetermined time period after the angular velocity signal enters the determination level, and no integration is performed outside the 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 angle detection method according to the present invention.

Figure 1 (in al, fl (T) and f2 (T
) is the angular velocity signal obtained from the output of the angular velocity sensor,
The signals f, (T) and fz(T) include a drift component (2) due to external disturbances. (T)=αT is included. IVC and -vc are voltage levels for predetermined level determination, and are used to determine whether the angular velocity signal exceeds the voltage level IV,l.

Then, based on the voltage level IVc l, an angular velocity signal f
By detecting the point in time when l (T) and fz (T) exceed the level IVC+ and the point in time when they enter the level IVc1, respectively, the time 1 when fl (T) and f2 (T) exceed IVC+ is determined. ．． Find / and 12/, respectively. Then time 1. / and 1, the time obtained by adding a predetermined time tc before and after / (tl ' + 2 tC)
and (2'+2tc), the angular velocity signals f, (T) and r2 (T) are integrated, respectively, and the area 3. as shown in FIG. tt and S2// are determined and detected as an angle.

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

This is because signals with M/, 1 or less and not within time tC are forcibly treated 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 draw a movement trajectory E as shown by the dashed line in FIG. Become. That is, it becomes possible to draw a movement locus within the predetermined range C without long-term correction, and it is possible to reduce the number of troublesome correction operations for position alignment.

FIG. 2 is a block diagram showing an example of the configuration of an integral type angle detection device that implements the method according to the present invention described above. and the A-D converter 1
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 is sent to the zero output. 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 voltage level IVc for determining the level of the angular velocity signal.
The level setting unit 13 for setting l is a comparator made of, for example, a window comparator, to which the voltage level 1 vcl is input to one input, and the angular velocity signal from the angular velocity sensor 2 is input to the other input. The output of the comparator 13 becomes H level when the angular velocity signal exceeds the voltage level lVcl, and becomes L level otherwise. Comparator 1
The output of 3 is the cent human power S of the R-S flip-flop 14.
is connected to the inverter 15 and the delay time 2t.
R-S flip-flop 14 via delay circuit 16 of
is connected to the reset human power R.

17 is an integrator, and when the Q output of the flip-flop 14 is at H level, the time t from the shift register 11 is
, the delayed digitized angular velocity signals are sequentially integrated to perform integration, 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 1, sequentially shifted in the shift register 11, delayed by time tc, and outputted. Sent out. When the level of the angular velocity signal exceeds lVCl, comparator 1
The output of 3 rises from L to H level, which causes R-S
Flip-flop 14 is set, and its output Q changes from L to 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 1Vcl, the output of the comparator 13 goes from H to L level, and the output of impark 15 goes from L to H level. In response, the output of the delay circuit 16 rises from L to the it level after 2tc time. As a result, the R-S flip-flop 14 is reset and its Q output changes from H level to L level, and the integrator 1
7 is stopped. That is, the period of the angular velocity signal accumulated by the integrator 17 is from tc time before the angular velocity signal exceeds +Vcl to 1c time after the angular velocity signal becomes 1 or less.

In addition, in the above-mentioned example, regarding the area S, tt, the entire dotted part is included as a drift error, but the polarity of the angular velocity at the time when M7C3 is exceeded and the angular velocity at the time tc before that time If the polarity of the signal is different,
As shown by the dotted line in FIG. 1(b), if the angular velocity signal is shifted and integrated by the level before time tc, the drift error can be reduced by this shift.

〔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, making it possible to perform angle detection with less drift error. When this is applied to a vehicle navigation system, it becomes possible to drive for a long time without any modification using an inexpensive angular velocity sensor.

[Brief explanation of the drawing]

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 device. 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. FIG. 2... Angular velocity sensor, 12... Level setting section, 13
...Comparator, 17...Integrator. Patent applicant Yazaki Sogyo Co., Ltd. Figure 3

Claims (1)

[Claims] In a method of detecting an angle by integrating an angular velocity signal from an angular velocity sensor, a determination level having a constant width of positive and negative is provided, and the determination is performed from a certain period of time before the time when the angular velocity signal exceeds the determination level. 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 enters a level, and no integration is performed outside the period.