JP2017096779A - Uwb measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultra wide band (UWB) measuring system capable of accurately measuring distance by removing an impact of difference in waveform characteristics.SOLUTION: A UWB measuring system for receiving an impulse UWB signal T to calculate distance performs envelope detection of the received UWB signal T to detect the waveform characteristic of a detection waveform S obtained by the envelope detection, checks a correction value database Z including a correction value corresponding to the waveform characteristic with the detected waveform characteristic to extract a correction value, and takes the extracted correction value into consideration to calculate distance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a UWB measurement system.

Conventionally, a measurement system that calculates a distance by transmitting and receiving a UWB (Ultra Wide Band) signal is known (see, for example, Patent Document 1 and Patent Document 2).
Such a measurement system calculates a distance by measuring a radio wave propagation time between UWB transmission and reception. As a specific circuit operation, as shown in FIG. 5, the received impulse UWB signal T is envelope-detected by an envelope detector 91, and pulse conversion is performed by a comparator 92 set to a predetermined threshold value. . The arrival time of the obtained pulse was measured with a digital circuit, and the distance was calculated based on the result.

JP 2011-80946 A JP 2014-65566 A

First, problems of the prior art will be described. In FIG. 6, the detection level (reference detection waveform) Sa obtained by envelope detection of the ideal UWB signal T and the signal level is weaker than the reference detection waveform Sa due to the influence of obstacles, radio wave propagation distances, and the like ( A detection waveform Sb in which the wave height H is reduced is shown in an overlapping manner.
In FIG. 7, the waveform changes due to the influence of the reflected wave, etc., and the rising waveform slope (slope) until reaching the threshold value becomes gentler than the reference detection waveform Sa. The waveform Sc and the reference detection waveform Sa are shown in an overlapping manner.

Originally, the radio wave propagation time is proportional to the distance and does not depend on the waveform characteristics such as the signal strength of the received signal and the rising waveform slope, but as shown in FIGS. 6 and 7, the waveform characteristics such as the signal level and the rising waveform slope are shown. Because of this, there is a difference in the time to reach the predetermined threshold value. Therefore, the rise timing (rise timing) Ea of the conversion pulse of the detection waveform Sa that is not affected by the detection waveform Sb, A time error ε occurs between the rising timings Eb and Ec of the conversion pulse of Sc. The pulse arrival time measured based on the pulse signal having such a time error ε includes an error.
That is, the prior art has a problem that an error occurs between the actual distance and the distance measurement value due to the influence of the difference in waveform characteristics such as the received signal strength and the waveform slope.

  Therefore, an object of the present invention is to provide a UWB measurement system capable of measuring a distance with high accuracy by eliminating the influence of a difference in waveform characteristics such as received signal strength and waveform slope.

In order to achieve the above object, the present invention provides an envelope detection of the received UWB signal in an UWB measurement system that receives an impulse UWB signal and calculates a distance, and obtained by the envelope detection. Detects the waveform characteristics of the detected waveform, compares the correction value database having a correction value according to the waveform characteristics and the detected waveform characteristics, extracts the correction value, and takes the extracted correction value into account for the distance It is a system that calculates
The waveform characteristic is the height of the detection waveform.
Alternatively, the waveform characteristic is a waveform slope of the rising edge of the detection waveform.

  According to the present invention, it is possible to perform high-precision distance measurement and positioning that do not include distance measurement errors due to the influence of differences in waveform characteristics such as received signal strength and waveform slope. With a relatively simple configuration, highly accurate ranging / positioning results can be obtained.

It is a block diagram which shows one Embodiment of the UWB measuring system of this invention. It is a circuit diagram which shows an example of a wave height detection circuit part. It is a circuit diagram which shows an example of a waveform slope detection circuit part. It is an action explanatory view, (a) is an action explanatory view for explaining a detection waveform with a gentle waveform slope, (b) is an action explanatory view for explaining an example of a waveform slope pulse. (c) is an operation explanatory diagram for explaining the charge amount of the capacitor. It is a circuit diagram which shows an example of a prior art. It is explanatory drawing for demonstrating the problem of a prior art, Comprising: (a) is explanatory drawing for demonstrating an example of a detection waveform, (b) is explanatory drawing which shows an example of the conversion pulse of a reference | standard detection waveform. (C) is an explanatory view showing an example of a converted pulse of a detection waveform having a weak signal level. It is explanatory drawing for demonstrating the problem of a prior art, (a) is explanatory drawing for demonstrating the other example of a detection waveform, (b) shows the other example of the conversion pulse of a reference | standard detection waveform. It is explanatory drawing, (c) is explanatory drawing which shows the other example of the conversion pulse of a detection waveform with a gentle waveform slope.

Hereinafter, the UWB measurement system of the present invention will be described in detail based on the illustrated embodiment.
The present invention is a UWB measurement system that receives an impulse UWB signal and calculates a distance. As shown in FIG. 1, the antenna unit 11 for receiving the UWB signal T and the received UWB signal T are amplified. A first amplifying unit 12 for detecting the envelope of the received UWB signal T and detecting it as a detected waveform S, and a first detecting unit for amplifying the detected waveform S from the envelope detecting unit 13 2 and a pulse converter 15 for converting the detected waveform S into a pulse signal at a predetermined threshold value (predetermined threshold value).

  Furthermore, a waveform characteristic detection circuit unit 17 that detects the waveform characteristic of the detected waveform S input from the second amplification unit 14 and outputs the detected waveform characteristic (waveform characteristic data I), and a correction value corresponding to the waveform characteristic And a storage unit 18 in which a correction value database Z is stored in advance.

  The correction value database Z has a plurality of waveform characteristic data I and correction value data Q associated with each waveform characteristic data I.

  Reference numeral 20 denotes a distance calculation processing unit. The distance calculation processing unit 20 collates the waveform characteristic detected by the waveform characteristic detection circuit unit 17 with the correction value database Z, and corresponding correction values (correction value data). Q) is extracted in the correction value determination process when the distance is calculated based on the arrival time obtained by measuring the pulse from the pulse converter 15 with a digital circuit. A distance calculation process is performed in which the calculated correction value is taken into account (corrected with the correction value).

  That is, the distance calculation processing unit 20 compares the input waveform characteristic data I with the waveform characteristic data I in the correction value database Z, and extracts the correction value data Q associated with the matched waveform characteristic data I. To do. The distance is calculated based on the extracted correction value data Q and the pulse arrival time (arrival time data) and is output as distance measurement value data L.

  For example, the correction value data Q is set to a positive / negative distance value (correction distance value), and the distance calculation processing unit 20 does not first add the correction value (as in the prior art) based on the pulse arrival time (temporary). Distance measurement value) is calculated, and then the distance (range measurement value) is obtained by adding or subtracting the correction distance value to the temporary distance measurement value.

  Alternatively, the correction value data Q is set to a positive / negative time value (correction time value), and the distance calculation processing unit 20 adds / subtracts the correction time value to / from the pulse arrival time, and then obtains the distance.

  The correction value data Q may be a coefficient (correction coefficient). Then, the distance is obtained by multiplying the provisional distance value by a correction value coefficient. Alternatively, the distance may be calculated after the pulse arrival time is multiplied by a correction coefficient.

In the first embodiment shown in FIG. 2, the waveform characteristic detection circuit unit 17 is configured with a wave height detection circuit unit 17A that detects the wave height H (see FIG. 6) of the detected waveform S as the waveform characteristic.
A detection amplifying unit (AMP) 31 to which the detection waveform S is input, and a peak value for rectifying the detection waveform S from the detection amplifying unit 31 and detecting the wave height H as a peak value of a voltage value (or current value). A detection circuit unit 32 and an AD conversion unit 33 that converts the detected peak value into digital data and outputs the data as wave height data Ia (waveform characteristic data I) are provided.
That is, it is a circuit for grasping the intensity of the signal level actually detected, converting the height H of the detected waveform S into the magnitude of the voltage value, and digitally outputting it.

The correction value database Z has a plurality of wave height data Ia and wave height distance correction value data Qa associated with each wave height data Ia.
For example, the wave height data Ia, which means that the wave height is smaller than the reference detection waveform Sa in FIG. 6, includes a negative correction distance value or a wave height correction value that means a positive correction arrival time value. Data Qa is associated.

Next, in the second embodiment shown in FIG. 3, the waveform characteristic detection circuit unit 17 includes a waveform slope detection circuit unit 17B that detects the waveform slope of the detection waveform S as the waveform characteristic.
A detection amplifying unit (AMP) 51 to which the detection waveform S is input, and a binary comparator unit 52 having high and low binary values (a high threshold and a low threshold) to which the detection waveform S from the detection amplifying unit 51 is input, , A waveform slope pulse generator 53 for outputting a pulse based on the two pulse signals from the binary comparator unit 52, and a voltage value for detecting the pulse signal output from the waveform slope pulse generator 53 as a voltage value A detection circuit unit 54, a detection voltage amplification unit (AMP) 55 for amplifying the detected voltage value, and converting the detected and amplified voltage value into digital data as waveform slope data Ib (waveform characteristic data I) And an AD converter 56 for outputting.
This is a circuit for converting the slope of the waveform slope of the detection waveform S into a voltage value and outputting it digitally.

  The binary comparator section 52 has a high value comparator 52a that performs pulse conversion on the detection waveform S with a high threshold (high threshold value), and a low value comparator 52b that performs pulse conversion on the detection waveform S with a low threshold (low threshold value). And have.

The waveform slope pulse creating unit 53 has an XOR circuit unit for outputting a pulse obtained by synthesizing the output pulse of the high value comparator 52a and the output pulse of the low value comparator 52b.
As shown in FIG. 4A, when the detection waveform S (detection waveform Sc having a gentle waveform slope) is input to the binary comparator unit 52, the threshold value is reached at the rising edge of the detection waveform S (for the low value). The detection result (by the comparator 52b) is input to one input section of the XOR circuit section, and the detection result that has reached the high threshold at the rising edge of the detection waveform S (by the high value comparator 52a) is input to the other input section of the XOR circuit. Entered.

Therefore, as shown in FIG. 4B, a pulse signal having a pulse width W with the rising time when the low threshold value is reached and the falling time when the high threshold value is reached is obtained.
The waveform slope pulse creation unit 53 is configured to output this pulse signal as a waveform slope pulse signal (creation result) of the rising edge of the detection waveform S.

As the waveform slope becomes steep, the time for the rising edge of the detection waveform S to reach the high threshold from the low threshold becomes shorter, and the pulse width W becomes shorter. Further, as the waveform slope becomes gentle, the time for the rising edge of the detection waveform S to reach the high threshold from the low threshold becomes longer, and the pulse width W becomes longer. The slowness of the waveform slope is converted into the length of the pulse width W.
The high threshold and the low threshold are preferably set so that the rising slope of the predetermined threshold value is detected in a range until the detection waveform S reaches the predetermined threshold value in the pulse converter 15 of FIG.

As shown in FIGS. 3 and 4, the voltage value detection circuit unit 54 has a capacitor C for charging for a time corresponding to the pulse width W of the pulse output from the waveform slope pulse creation unit 53.
The shorter the pulse width W, the smaller the amount of charge, and the smaller the voltage value Va of the capacitor C. The longer the pulse width W, the larger the amount of charge and the larger the voltage value Va of the capacitor C.
That is, the voltage value Va is small when the waveform slope is steep, and the voltage value Va is large when the waveform slope is gentle. The slope of the waveform slope is converted to the magnitude of the voltage value.

  The voltage value Va obtained by the voltage value detection circuit unit 54 is input to the AD conversion unit 56 via the detection voltage amplification unit 55 and converted into digital data. The converted voltage value Va is output as waveform slope data Ib).

The correction value database Z has a plurality of waveform slope data Ib and waveform slope distance correction value data Qb associated with each waveform slope data Ib.
For example, waveform slope correction value data Qb meaning a negative correction distance value or positive correction time value is added to the waveform slope data Ib meaning that the waveform slope is gentler than the reference detection waveform Sa of FIG. It corresponds.

  The distance calculation processing unit 20 collates the input waveform slope data Ib with the waveform slope data Ib in the correction value database Z, and the waveform slope distance correction value data Qb associated with the matched waveform slope data Ib. To extract.

In addition, the waveform slope detection circuit unit 17B has the subsequent pulses output from the waveform slope pulse generation unit 53 until the pulse output from the waveform slope pulse generation unit 53 is captured (read) by the AD conversion unit 56. The charge masking signal is output so as to prevent the capacitor C from being charged (charge), and the charge masking process for turning off the switch SW is performed (the control circuit unit for charge masking is provided).
When the AD conversion unit 56 finishes capturing, the reset signal is output to discharge the capacitor C, and the output of the charge masking signal is stopped and the switch SW is turned ON to charge the capacitor C. Is configured to be possible.

  In FIG. 1, an antenna unit 11 is an antenna member having an antenna element, a first amplifier unit 12 is a high frequency amplifier (LNA), and an envelope detector unit 13 is a detector (envelope). The second amplifying unit 14 is an amplifier (AMP), the pulse converting unit 15 is a comparator (comparator) set to a predetermined threshold (predetermined threshold value), and a distance calculation processing unit Reference numeral 20 denotes an arithmetic processing unit such as a CPU or an integrated circuit, or a baseband circuit unit or a digital processing circuit. A storage unit 18 stores a storage unit such as an integrated circuit, RAM, ROM, HD (hard disk), flash memory, or the like. It is a vessel.

  The present invention can be applied to a system that calculates the distance by transmitting and receiving an impulse UWB signal and measuring a radio wave arrival time between transmission and reception. For example, a UWB signal is transmitted from a fixed transmitter to a mobile receiver and a UWB signal is received. The distance between the mobile receiver and the fixed transmitter can be measured, and the position of the mobile receiver can be applied to the detection system. For example, a fixed transmitter / receiver is provided in a warehouse, and a moving tag with a transmitter / receiver is provided on a moving body such as a forklift or a transported object, so that it can be applied as a system for ranging and positioning a forklift or transported object. In addition, the UWB signal is transmitted from the transceiver, the response signal from the measurement object is received by the transceiver, the distance to the measurement object is measured, and a plurality of transceivers fixed at predetermined positions In this system, the distance to the measurement object is calculated and the position of the measurement object is detected (positioned) three-dimensionally based on the distance measurement value of each transceiver. Further, the present invention can be applied to a ranging radar system that applies a UWB signal to a measurement object, receives a reflection signal, and measures a distance.

  In the present invention, the design can be changed, and the wave height detection circuit unit 17A may have a configuration other than the illustrated circuit as long as the difference in the wave height H of the detection waveform S can be converted into digital data. Further, the waveform slope detection circuit unit 17B may have a configuration other than the illustrated circuit as long as the difference in the waveform slope of the detection waveform S can be output as digital data. Further, calculating the distance with the correction value taken into account may obtain the distance measurement value by a combination of four arithmetic operations other than those described above.

  As described above, the UWB measurement system according to the present invention receives the impulse UWB signal T and calculates the distance, and detects the received UWB signal T by envelope detection and obtains it by envelope detection. The detected waveform characteristic of the detected waveform S is detected, the correction value database Z having a correction value corresponding to the waveform characteristic and the detected waveform characteristic are collated to extract a correction value, and the extracted correction value is taken into account Since the distance is calculated, it is possible to eliminate the influence of the difference in waveform characteristics such as the strength of the received signal and the waveform slope, and to perform highly accurate distance measurement and positioning that do not include the distance measurement error.

  Further, since the waveform characteristic is the wave height H of the detection waveform S, an accurate distance that does not include a distance error caused by the signal intensity can be output.

  Alternatively, since the waveform characteristic is the waveform slope of the rising edge of the detection waveform S, an accurate distance that excludes the influence of the rising slope difference of the detection waveform S can be output.

H Wave height S Detection waveform T UWB signal Z Correction value database

Claims (3)

In a UWB measurement system that receives an impulse UWB signal (T) and calculates a distance,
Envelope detection of the received UWB signal (T) to detect the waveform characteristics of the detected waveform (S) obtained by the envelope detection, and a correction value database (Z) having correction values corresponding to the waveform characteristics A UWB measurement system that compares the detected waveform characteristics with each other and extracts a correction value, and calculates the distance in consideration of the extracted correction value.   The UWB measurement system according to claim 1, wherein the waveform characteristic is a wave height (H) of the detection waveform (S).   The UWB measurement system according to claim 1, wherein the waveform characteristic is a waveform slope of a rising edge of the detection waveform (S).

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