JPH0476480A - Pulse ranging device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring device that transmits and receives pulse signals.

[Conventional technology]

In a pulse distance measuring device that measures the delay time between sending out a transmission pulse and detecting the transmission pulse reflected by a target as a reception pulse, if you try to calculate the delay time by counting only with the reference clock, The existing counter is 1
This is enough to count clocks with a frequency of about 0.00 MHz. However, the resolution that can be counted with a clock of 100 MI (z) is about 10 ns, and in the case of a device using light waves, assuming the speed of light is 300,000 ri per second, the resolution that can be counted is about 10 ns.
It is only possible to decompose distances of about m. 10+a+n
Just trying to have a distance resolution of about 1/(
10÷(30X10”)l =3Xl O”l:7]
This shows that unless a frequency of 30 Gllz is used as a clock, it is not possible to measure a distance of even about 10 mm. Here, a frequency that is easy to handle economically and technically is used as the counting clock of the counter, and a rough delay time can be determined by integrating the count number obtained here and the counting clock, and one clock of the clock is used. A device has appeared that can calculate even the smallest delay time by calculating the fraction within.

In other words, the fraction within one clock is determined by the charging circuit that starts charging by the received pulse on the next clock pulse.
- It is determined from the charging voltage value at that time.

[Problems to be solved by the invention] However, in pulse distance measurement, high-output pulses and
Because lasers and electromagnetic pulses with strong electric fields are used, due to energy density, it is necessary to take a long time interval from one pulse transmission to the next. There is a problem in that it is necessary to increase the number of measurements in order to stabilize the elements themselves, such as capacitors, used in the charging circuit that generates the analog quantity to be converted.

Therefore, an object of the present invention is to improve measurement accuracy by improving the stability of circuit elements that perform time-voltage conversion.

[Means for solving problems]

The present invention transmits a transmission pulse toward a target object, receives the transmission pulse reflected by the target object as a reception pulse, and calculates the A pulse distance measuring device for determining the distance to a target includes a clock oscillator (1) that outputs a reference clock, a clock oscillator (1) that is synchronized with the reference clock, and
A stationary oscillation wave generator (
11), a transmission pulse starting means (2, 3, 4) for emitting a transmission pulse in synchronization with the reference clock, a receiving means (8, 9, 10) for receiving a reception pulse, and a transmission pulse generator for emitting the transmission pulse. counter means (50,
5), reading means (2.6) for reading the level of the steady oscillation wave signal when the receiving means (8, 9, 10) receives the received pulse; phase shift means (6, 2) for providing a phase shift between the transmitted pulse and the stationary oscillation wave signal so that the phase shift occurs in a portion where the level of the wave signal changes continuously; and the counter means (5, 2); 5O) and the reading means (12
, 6) and a calculation means (6) for calculating the distance to the target based on the amount of phase shift of the phase shift means (6, 2). It is a pulse distance measuring device.

[Effect]

In the present invention, since a circuit that performs time-to-voltage conversion is configured using a steady-state oscillation generator, the circuit elements constituting the circuit are in a normal operating state, so it is possible to improve the stability of the circuit elements.

Therefore, the measurement accuracy of pulse distance measurement can be improved.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a flowchart of a control section used in FIG. 1, and FIG. 3 is a timing chart for explaining the operation of FIG. 1.

The reference clock oscillator 1 outputs a temperature compensated reference clock. The reference clock 1 includes a pulse generation circuit 2,
A frequency divider 50, a control section 6 composed of a microcomputer, and a steady oscillation wave generator 11 are connected, and each circuit 2, 6, 11, and 50 operates in synchronization with a reference clock.

The pulse generation circuit 2 outputs pulses synchronized with the reference clock according to instructions from the control section 6.

A transmission drive unit 3 is connected to the pulse generation circuit 2, and the transmission drive unit 3 causes the transmitter 4 to emit a transmission pulse in response to a pulse input from the pulse generation circuit 2 to the transmission drive unit 3.

The frequency divider 50 divides the reference clock to create an approximate counter clock and inputs it to the approximate counter 5.
For example, the period of the approximate counter clock is four times the period of the reference clock. The control section 6 operates according to the flowchart shown in FIG. 2, and inputs the detection signal from the received signal detection section, the count value of the rough counter 5, and the A/D conversion signal of the A/D conversion section 12 in addition to the reference clock. On the other hand, the approximate counter 5
, a display command to the display unit 7 , a pulse generation command to the pulse generation circuit 2 , a control command to the stationary oscillation wave generator 11 , and a conversion start command to the A/D conversion unit 12 .

The stationary oscillation wave generator 11 is, for example, a charging/discharging circuit using a capacitor, and has a charging switch and a short-circuiting switch, and when the charging switch is turned on, the voltage between the terminals of the capacitor changes to a plurality of reference clocks. It is configured so that the voltage between the terminals of the capacitor becomes zero when the charging switch is turned off and the shorting switch is then turned on. The on/off state is controlled by a control command from the control section 6. Therefore, the output signal of the stationary oscillation wave generator 11, which is the voltage between the terminals of the capacitor, is, for example, as shown in FIG. This will be repeated. The period of the clock for the approximate counter 5 and the charging/discharging period of the stationary oscillation wave generator 11 are shown in FIG. 3(d) and (
It corresponds as shown in e).

The receiver 8 receives a received pulse that is a transmitted pulse transmitted from the transmitter 4 and reflected by a target object. When the transmitted pulse is pulsed light, a photoelectric conversion element with a fast response speed, such as a photodiode, is used.

The received pulse converted into an electrical signal by the reception unit 1B is amplified by the amplification unit 9 and then input to the received signal detection unit 10. When the received signal detection unit 10 receives the amplified received pulse, A signal indicating that a received pulse has been input is input to the section 6.

With such a configuration, the operation of the apparatus will be explained with reference to FIG. 2, which is a flowchart of the control unit 6. When measurement starts, the control unit 6 determines whether a mode for correcting environmental factors such as temperature is selected or not. Determine whether or not (step 61)
, if the correction mode is selected, both the charging switch and the short-circuit switch of the stationary oscillation wave generator 11 are turned off at a predetermined first phase position of the stationary oscillation wave signal (step 62). ), sample and hold the voltage value at a predetermined first phase position,
The A/D converted data is read by the A/D converter 12 (step 63).

After reading the data, turn on/off the charging switch and shorting switch again to sample and hold the charging voltage value at the predetermined second phase position (
Steps 64.65.62.63).

Taking the data of two points, y=ax+b(y;
1st and 2nd phase positions (expressed in time within the period), X; charging voltage values at the 1st and 2nd phase positions, a
, b indicate correction coefficients), the correction coefficients a and b are determined (step 66).

Then, reset the approximate calculation number 5 (Step 67)
, instructs the pulse generation circuit 2 to generate a pulse (step 6). As a result, the approximation counter 5 counts the approximation count clock after being reset, and the pulse generation circuit 2 outputs a pulse. Therefore, a transmission pulse is output from the transmitter 4 via the transmission driver 3. Note that this transmission pulse is sent out in the form of radio waves, light waves, or the like.

After issuing a pulse generation command to the pulse generation circuit 2, the control unit 6 monitors a signal from the reception signal detection unit 10 indicating whether or not a reception pulse is detected, and when a reception pulse is detected (
In step 69), the approximation counter 5 stops counting the clocks and digits, and both the charging switch and the discharging switch of the stationary oscillation wave generator 11 are turned off to stop charging and discharging the capacitor, and the sample hold is stopped. (step 70).

Thereafter, in step 71), it is determined whether the steady oscillation wave signal is in the charging period when the received pulse is detected, that is, whether the received pulse is generated at an appropriate phase of the steady oscillation wave signal. If it is not generated at the phase, the stationary oscillation wave generator 11 starts on/off control of the charging switch and the discharging switch so that a stationary oscillation wave signal is output, and the estimation counter 5 is reset. Step 72), the pulse generation circuit 2 is controlled so that the timing of generation of the transmission pulse is shifted by one period of the reference clock (step 73), and the transmission pulse is sent out (step 68). Then, step 69.70. until the received pulse reaches the proper phase of the stationary oscillation wave signal.
71, 72, 73, 67, 68 are repeated, and when a received pulse is generated at the appropriate phase, the stationary oscillation wave generator 1
1 sample hold voltage (voltage between capacitor terminals)
is subjected to A/D conversion by the A/D converter 12, and the resulting value is read in, as well as the count value of the approximate counter 5 (step 74).

Then, it is determined whether a certain number of distance measurement data have been read (step 75), and if they have not been read, the process returns to step 67; if they have been read, arithmetic processing is performed in step 76 to obtain a distance measurement value.

In other words, the count value of the approximate counter 67 is #! The approximate time Y obtained by multiplying the period of the clock for the calculation counter and the time Y obtained by adding y obtained from the formula y=ax+b obtained in step 66 to the time Y+Y is used to calculate the time from when the transmit pulse is sent to when the receive pulse is received. The time is determined, and the distance M(Y1y)·C/2 to the target is determined from this time y+y and the moving speed of the pulse (for example, the speed of light C).

The obtained distance is then displayed on the display section 7 (step 77).

The above operation can be further explained using the timing chart of FIG. 3 as follows.

That is, a transmission pulse (Fig. 3 (b)) synchronized with the reference clock (Fig. 3 (a)) is generated, and then a reception pulse (Fig. 3 (b)) is generated.
Figure 3(C)) is produced.

The approximation counter 5 counts the rise of the approximation counter clock (for example, FIG. 3(d)) that is synchronized with the reference clock, but if the frequency of the reference clock is slower than the counter's counting speed, You may count the rise.

The stationary oscillation wave generator 11 performs charging and discharging in synchronization with a reference clock such as the third [11(e)], but when a received pulse occurs in a charging period (equivalent to three cycles of the reference clock),
The charging voltage is held.

However, as shown in FIG. 3(f), the stationary oscillation wave generator 1
If the distance is such that a received pulse occurs in the discharge section of the output signal 1 (Figure 3 (e)), the transmitted pulse is generated with a shift of one period of the reference clock (Figure 3 (g)). As a result, the generation timing of the received pulse is shifted by one cycle of the reference clock, that is, the output signal of the stationary oscillation wave generator r&11... is within the charging period of the stationary oscillation wave signal (Fig. 3 (e)). (Fig. 3 (h)).

Note that the control unit 6 controls the charging and discharging of the capacitor by controlling the on/off of the charging switch and the short-circuit switch used in the stationary oscillation wave generator 11, so that the stationary oscillation wave is generated. Since it is known whether the output signal of I11 (steady oscillation wave signal) is in the charging section or the discharging section, it is possible to identify whether the received pulse occurs in the charging section or the discharging section of the output signal. .

In addition, in the above embodiment, the generation timing of the transmission pulse was adjusted so that the reception pulse occurred during the charging period of the stationary oscillation wave signal, but as shown in FIG. 4, the phase of the stationary oscillation wave signal It is also possible to cause the received pulse to occur during the charging period of the stationary oscillation wave signal by shifting the reference clock from the reference clock (by shifting the on/off timing of the charging switch and the discharging switch). Furthermore, a stationary oscillation wave signal that repeats charging and discharging at each predetermined period of the reference clock is prepared by sequentially shifting the signal by one period of the reference clock (for example, charging for three periods of the reference clock mentioned above,
In the case of a stationary oscillation wave signal that discharges for one cycle of the reference counter, a maximum of four stationary oscillation waves are sufficient. You can also do it.

According to the embodiment of the present invention described above, (]), since the steady oscillation wave is used as the interpolation data to find the fraction within one period of the IQ calculation counter clock, the interpolation data can be stabilized. Improvement can be measured.

(2), timing not suitable as interpolation data (third
In the figure, this corresponds to the discharge interval), and can be operated so that the received pulse falls within a specific range obtained by phase-dividing the interpolation data, so interpolation data can be obtained at appropriate timing.

(3), steps 62.63.64.6 shown in FIG.
5.6G makes it easy to correct changes in the conversion ratio due to environmental changes such as temperature with respect to time-voltage conversion of interpolation data.

Note that, as described in (2) above, since the received pulse can be made to fall within a specific range obtained by phase-dividing the interpolation data, the following secondary effects occur.

(1) By using an approximate counter clock which is a reference clock multiplied by multiple times as shown in FIG. 3, the received pulse can be made to arrive at a timing that will not cause a counting error in the approximate count.

(ii) As the input range for A/D conversion, the minimum system is one clock of the reference counter corresponding to a specific range obtained by phase-dividing the interpolation data, and the analog amount (interpolated data) of the faint part before and after that. It would be good if it could be converted into a digital quantity. This shows that the demerit of obtaining a large Guinaminck range of A/D conversion and generating an analog quantity that is multiple times the reference black signal is not particularly large.

In addition, if a configuration is adopted in which multiple pieces of interpolation data are sequentially shifted by one period of the reference clock, the circuit becomes larger, but if the interpolation data cannot be obtained at an appropriate timing, the above (2) It is also possible to obtain one measurement value by sending out a single pulse without having to carry out distance measurement operations multiple times by sequentially shifting received pulses.

〔Effect of the invention〕

As described above, according to the present invention, by configuring a circuit that performs time-voltage conversion using a stationary oscillation wave generator, it is possible to improve the stability of the circuit elements that constitute the circuit.
The measurement accuracy of pulse distance measurement can be improved.

[Explanation of symbols of main parts]

1... Clock oscillator, 2...Pulse generation circuit, 4...Transmitter, 50... Frequency divider, 5...Approximate counter, 6...control unit, 8...Receiver, 10... Received signal detection section, 11...Stationary oscillation wave generator.

Claims (1)

[Claims] A transmission pulse is transmitted toward a target object, a transmission pulse reflected by the target object is received as a reception pulse, and the transmission pulse is determined based on the time from transmitting the transmission pulse to receiving the reception pulse. , a pulse distance measuring device for determining the distance to the target object, comprising: a clock oscillator that outputs a reference clock; and a stationary clock oscillator that is synchronized with the reference clock and whose level changes continuously within a cycle that is multiple times the reference clock. a stationary oscillation wave generator that outputs an oscillation wave signal; a transmission pulse generation means that emits a transmission pulse in synchronization with the reference clock; a reception means that receives a reception pulse; counter means that starts counting a clock synchronized with a reference clock and ends counting of the reference clock upon reception of the received pulse; and counter means that measures the level of the steady oscillation wave signal when the receiving means receives the received pulse. reading means for reading; and phase shifting means for providing a phase shift between the transmitted pulse and the stationary oscillation wave signal such that the received pulse occurs in a continuously changing portion of the level of the stationary oscillation wave signal. and calculating means for calculating the distance to the target object based on the counted value of the counter means, the read value by the reading means, and the phase shift amount of the phase shifting means. Pulse ranging device.