JP3177708B2 - Distance measurement method with lightwave distance meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring method using a lightwave distance meter.

[0002]

2. Description of the Related Art Distance measurement by a conventional lightwave distance meter is performed according to a control flow shown in FIG. That is, in Step 10, after switching to a certain modulation signal, radiating the light beam whose amplitude is modulated by the modulation signal toward the reflector, and making the reflected light from the reflector enter the light receiving element to obtain the ranging signal The reference signal is obtained by switching the shutter or the like so that the amplitude-modulated light beam directly enters the light receiving element.

[0003] In step 11, the operation time of the shutter or the like plus a margin time is delayed by, for example, 200 milliseconds. In step 12, the count of the wave number of the reference signal corresponding to the phase difference between the ranging signal and the reference signal is counted. Start. When the count value is obtained in step 13, 1 is added to the count number thus far in step 14, and in step 15, whether the number of times necessary to obtain the distance measurement value (conventionally, about 50 or 100 times) has been reached. And Y
If it is ES, the process ends. If it is NO, step 12 is executed.
Return to and repeat the count.

[0004]

According to the conventional distance measuring method using an optical distance meter, the delay time until the wave number is counted is considered the worst state, so that the time is wasted in the best state. Will do. That is, when the modulation frequency is 3
In order to switch between the ranging signal and the reference signal at each modulation frequency, the delay time in step 11 is accumulated to be 200 ms × 6 (ranging signals f ₁ , f ₂ ,
reference signal and the three f ₃ f _1, f _2, a total of six times in three f ₃₎ of the time delays. An object of the present invention is to provide a conventional distance measuring method using a lightwave distance meter that can eliminate such a useless time delay and reduce the measurement time.

[0005]

In order to achieve the above object, a modulation signal of a plurality of frequencies is selectively switched, a light beam whose amplitude is modulated by the modulation signal is radiated toward a reflector, and the light is reflected by the reflector. The reflected light from is converted to a ranging signal by a light receiving element, a light beam whose amplitude is modulated by switching a shutter or the like is directly emitted to the light receiving element, converted to a reference signal by the light receiving element, and then converted to a reference signal. Counting the wave number of the reference signal corresponding to the phase difference with the reference signal, in a distance measuring method by an optical distance meter that measures the distance from the count value to the reflecting mirror, when switching the modulation signal and the distance measuring signal Immediately upon switching to the reference signal, the wave number counting is started and the counting is repeated, and it is determined whether or not each count value is within a predetermined error range. value And calculates the distance fetches the required number.

[0006]

The counting of the wave number of the reference signal corresponding to the distance measurement value is started immediately when the modulation signals of a plurality of frequencies are selectively switched and when the reflected light and the reference light incident on the light receiving element are switched. It is determined whether each count value obtained by repeating is within a predetermined error range, and when the count value falls within the predetermined error range, the count value is taken in a necessary number of times and the distance to the reflecting mirror is calculated. . Therefore, counting can be started from the time when the state at the time of the switching becomes normal, and the measurement time can be shortened.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
FIG. 1 is a block diagram showing a main part of an electro-optical distance meter used for carrying out the present invention. In the figure, 1 is a distance measuring circuit, 2 ₁ , 2 ₂
Is an input selection circuit, 3 is a counter, and 4 is a CPU. The distance measuring circuit 1 includes a light emitting element, a light receiving element, and three types of frequencies f ₁ , f ₂ , and f ₃ for modulating a light beam emitted from the light emitting element.
And a gate circuit for selectively outputting the three types of modulation signals, and an energizing circuit such as a shutter for selectively inputting the reference light and the distance measuring light to the light receiving element. There, the input selection circuit 2 _2, the frequency f ₁ selection signal (input 1), selects the output frequency f ₂ selection signal (input 2) and the frequency f ₃₎ selection signal (input 3) with the input selection signal from the CPU4 Input selection circuit 2 ₂
Is to selectively output a ranging light selection signal (input 4) and a reference light selection signal (input 5) by an input selection signal from the CPU 4. Frequency f ₁ ~f ₃ to be output from the input selection circuit 2 ₁
The selection signal selectively opens and closes the gate circuit of the distance measuring circuit 1, outputs a modulation signal having a frequency corresponding to the selection signal, and amplitude-modulates a light beam output from the light emitting element with the modulation signal.
Distance measuring light selection signal or the reference light selection signal output from the input selection circuit 2 ₂ for selectively receiving element distance measuring light or the reference light biasing circuit such as a shutter of the distance measuring circuit 1 selectively actuated to Make it incident. The CPU 4 outputs the two types of input selection signals and the count start signal and the end signal of the counter 3 according to a control flow described later, and adds the count value from the counter 3 a required number of times to obtain a distance measurement value. .

[0008] The present invention will be described how along the control flow chart shown in FIG. 2, in step 20, CPU 4 outputs a switching signal such as a shutter, the signal of the frequency f ₁ based on the signal is selected and output and, first type at a frequency f ₁ to the distance measuring light receiving element which is amplitude-modulated, then the shutter as the reference light enters the light receiving element is switched. In the switching of the shutter (step 20), a delay of about 10 milliseconds is provided. Since this is about 1/20 of the conventional 200 milliseconds, the flow of the delay is omitted in the flow of FIG. And not shown. Step 2
At 1, a count start signal is output to the counter 3,
In step 22, the counter 3 counts the number of pulses of the reference signal corresponding to the phase difference between the ranging signal and the reference signal to obtain a count value. In step 23, 1 is added to the number of counts so far, and in step 24, it is determined whether this count is equal to 3, less than 3, or 3 or more. If it is less than 3, the process returns to step 21 and the counter 3 starts counting again. In the present invention, a delay time of 200 milliseconds in step 11 is about 100 milliseconds if a determination time of three times is added to 10 milliseconds in the present invention. This is a half of the conventional 200 milliseconds delay time. When the number of counts reaches three from the beginning in step 24, the process proceeds to step 25, where the three count values are compared with each other to determine whether or not each count value is within a predetermined error range. If it has exceeded, the process proceeds to step 26, subtracts 1 from the count, returns to step 21, and starts counting again. Step 24
Then, the oldest count value is discarded and the latest count value is fetched, and the three count values are compared again at step 25. If the three count values do not exceed the predetermined error range, in step 27, the three count values are fetched and the process returns to step 21 to obtain the count values again. This count value is sequentially added in step 28, and the process is terminated when the number of counts necessary for taking in the count value is reached in step 29. obtain. Therefore, the present invention can be used as follows. If the conventional method shown in FIG. 3 is combined with the present invention shown in FIG. 2 to select any one of the methods at the time of measurement, positioning such as staking at the time of surveying can be performed in half of the conventional measurement time. Further, since the measurement time is about half and the accuracy is about the same as the conventional one in the configuration of the present invention, a single distance meter can be used.

[0009]

According to the present invention having the above-described configuration, an advantage is obtained that the distance measurement time by the lightwave distance meter can be reduced without increasing the error as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a lightwave distance meter used for carrying out the method of the present invention

FIG. 2 is a control flow chart of an example of the method of the present invention.

FIG. 3 is a control flow chart of a conventional method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Distance measuring circuit 2 ₁ , 2 ₂ input selection circuit 3 Counter 4 CPU

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-242187 (JP, A) JP-A-54-91362 (JP, A) JP-A-56-132580 (JP, A) 162674 (JP, U) Actually open sho 59-253 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /48-7/51 G01S 17/00-17/95

Claims (1)

(57) [Claims] 1. A modulation signal of a plurality of frequencies is selectively switched, a light beam whose amplitude is modulated by the modulation signal is emitted toward a reflecting mirror, and the reflected light from the reflecting mirror is converted into a ranging signal by a light receiving element. A light beam whose amplitude is modulated by switching a shutter or the like is directly emitted to the light receiving element, converted into a reference signal by the light receiving element, and then a reference corresponding to a phase difference between the distance measurement signal and the reference signal. In a distance measuring method using an optical distance meter that counts the number of waves of a signal and measures the distance from the count value to a reflecting mirror, the counting of the number of waves is started immediately when a modulation signal is switched or when a ranging signal and a reference signal are switched. Then, the count is repeated, it is determined whether each count value is within a predetermined error range, and when the count value is within the predetermined error range, the count value is taken in a necessary number of times to calculate the distance. Characteristic distance measurement method using lightwave distance meter.