JP2009288018A - Radiowave sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiowave sensor capable of appropriately setting an integration time for a pulse width, even when there are component variations, and detecting the distance up to an object accurately by using a radio signal having pulses generated at prescribed intervals. <P>SOLUTION: The radiowave sensor includes: a transmitting part 1 for transmitting the radio signal having pulses at the prescribed intervals via an antenna 2; the antenna 2 for receiving the radio signal; a detection block 3 for performing envelope detection of the received signal and outputting a detection signal; an integrator circuit 5 for integrating the detection signal in an integration period; a phase controller 8 for causing the integration period to a pulse contained in the output of the detection block 3, to synchronize with the pulse; an A/D converter 6 for converting the integrated value into a digital signal, a signal processing part 7 for calculating, based on the output of the A/D converter 6 at a distance up to the object, based on the difference, in the phases between a transmitted pulses and their received reflected wave pulses, and an integration time controller 9 for changeably setting the integration time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio wave sensor.

  Conventionally, there is a radio wave sensor that detects the distance to an object using radio waves, the radio wave is transmitted from the transmission means, the reflected wave that hits the object is received by the reception means, and the phase difference between the transmission radio wave and the reception radio wave is detected. Based on this, the distance to the object is detected (see, for example, Patent Document 1).

Also, there are radio waves that use radio signals that generate pulses at a predetermined period as radio waves to be transmitted. The reflected radio waves that are reflected when the transmitted radio signals hit an object are received, and the received signals are detected by envelope detection to generate detection signals. Then, the pulse part of this detection signal is integrated over a predetermined integration period, and based on this integration value, the phase difference between the transmitted pulse and the received pulse is detected, and the distance from the phase difference to the object is calculated. is doing.
JP2007-15596A

  As described above, an integration circuit or an amplification circuit is used for a radio wave sensor that uses a radio signal that generates a pulse at a predetermined cycle. Since an IC or the like to be used varies depending on lots, an integration gain or an amplification gain is used. In addition, the rising characteristics of received pulses are different. Therefore, if a state in which the length of the integration period with respect to the pulse width (integration time) is not set appropriately occurs, the sensor sensitivity is lowered, and the accurate distance to the object cannot be detected. Specifically, when the integration time is long with respect to the pulse width, sensitivity decreases due to the influence of noise in the integration process, and when the integration time is short with respect to the pulse width, the time for accumulating charge in the integration process is reduced. Sensitivity decreases because of insufficientness.

  The present invention has been made in view of the above-described reasons, and the object thereof is to use a radio signal that can appropriately set an integration time with respect to a pulse width even when there are component variations, and generates a pulse at a predetermined cycle. An object of the present invention is to provide a radio wave sensor that can detect an accurate distance to an object.

  The invention of claim 1 transmits a radio signal composed of pulses generated at a predetermined period, receives a reflected wave reflected by the transmitted radio signal hitting an object, and transmits the transmitted radio signal and the received reflected wave. In a radio wave sensor that detects a distance to an object based on a phase difference, a transmission unit that transmits a radio signal composed of pulses of a predetermined cycle, a reception unit that receives a radio signal transmitted by the transmission unit, and a reception unit The detection means for detecting the received signal by envelope detection and outputting the detection signal; the integration means for integrating the output of the detection means in the integration period and outputting the integrated value; and the integration period for the pulse included in the output of the detection means A phase control means for setting the phase to be variable and synchronizing the integration period with the pulse; an A / D conversion means for outputting a signal intensity obtained by converting the output of the integration means into a digital signal; A signal for detecting a phase difference between one or more transmitted pulses and one or more pulses of a received reflected wave based on the output of the / D conversion means, and calculating a distance to the object based on the phase difference It is characterized by comprising processing means and integration time control means for variably setting the integration time which is the length of the integration period.

  According to the present invention, even when there is a variation in the characteristics of the integration means due to the variation in parts in each IC or the like used, the integration time of the integration means is adjusted for each individual radio wave sensor to obtain the pulse width of the received pulse. Since they are matched, individual differences in distance measurement accuracy can be suppressed, and a decrease in distance measurement accuracy can be prevented. Therefore, even when there are component variations, the integration time with respect to the pulse width can be set appropriately, and the accurate distance to the object can be detected using a radio signal that generates pulses at a predetermined period.

  According to a second aspect of the present invention, in the first aspect, the receiving unit is disposed at a predetermined distance from the transmitting unit, receives a radio signal transmitted by the transmitting unit, and the phase control unit determines the integration period. The phase is set to a first phase that does not include a pulse in the integration period and a first signal intensity is measured, and then the phase of the integration period is set to a second phase that includes the entire pulse in the integration period. A second signal strength obtained by subtracting the first signal strength from the measured signal strength is derived, and then the phase of the integration period is obtained as a third signal strength that is half of the second signal strength. And a controller for setting the integration time based on the difference between the second phase and the third phase by the integration time control means.

  According to the present invention, since the controller automatically sets the integration time, the setting work can be simplified and the production efficiency can be improved.

  As described above, in the present invention, even when there are component variations, the integration time with respect to the pulse width can be set appropriately, and an accurate distance to the object is detected using a radio signal that generates pulses at a predetermined period. There is an effect that can be.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The radio wave sensor of the present invention detects a distance to an object using a radio signal that generates a pulse at a predetermined cycle. FIG. 1 shows the basic configuration of the pulse sensor that generates a pulse at a predetermined cycle. The transmitting unit 1 that converts the pulse signal output from the transmitting unit 1 into a radio signal, transmits the reflected signal, receives the reflected wave, and envelopes the signal received by the antenna 2 to detect the detected signal K1. Detection block (detection means) 3 to be output, switching unit 4 that connects the antenna 2 to the transmission unit 1 or the detection block 3 so as to be switchable, and an integration that integrates the output of the detection block 3 in an integration period and outputs an integration value A circuit (integration means) 5, an A / D converter (A / D conversion means) 6 that converts the output of the integration circuit 5 into a digital signal, and the transmitted 1 to 1 based on the output of the A / D converter 6 Multiple pals And a signal processing unit (signal processing means) 7 for calculating a distance from the phase difference to the object, and a phase of an integration period with respect to the received pulse can be freely changed. A phase control unit (phase control unit) 8 for setting and an integration time control unit (integration time control unit) 9 for setting the length of the integration period (integration time) to be variable are provided. The antenna 2 constitutes reception means for receiving a reflected wave of a radio signal, and the transmission unit 1 and the antenna 2 constitute transmission means for transmitting a radio signal that generates a pulse at a predetermined period.

  Here, the radio signal will be described with reference to FIG. FIG. 2A is a diagram showing a waveform of a pulse signal transmitted / received via the antenna 2, and the pulse signal has a pulse P1 generated in a predetermined cycle, and each pulse P1 is a super It consists of short pulses. FIG. 2B is an enlarged view of the detection signal K1 in which the pulse signal in the range A in FIG.

  Next, the operation of the radio wave sensor will be described. The switching unit 4 is controlled by the signal processing unit 7. First, the transmission unit 1 outputs a pulse signal in a state where the switching unit 4 connects the output of the transmission unit 1 to the antenna 2. A radio signal is transmitted from the antenna 2 via 4. Next, the signal processing unit 7 switches the switching unit 4 to connect the antenna 2 to the detection block 3, and receives the reflected wave reflected by the transmitted radio signal hitting the object by the antenna 2. The detection block 3 shown in FIG. 1 includes an amplifying unit 30 that amplifies a reception signal received by the antenna 2, and a filter (band filter) 31 that extracts a component of a use frequency band of a radio signal from an output signal of the amplifying unit 30. And an detector 32 for detecting the output signal of the filter 31 as an envelope and outputting the detected signal as a detected signal K1, and the detected signal K1 is an envelope of the pulse P1 of the pulse signal as shown in FIG. The detected reception pulse P2 is generated at a predetermined period. By the detection block 3, for example, a reception signal in a band of 3.8 GHz received by the antenna 2 is frequency-converted to about 500 MHz, and the detection signal K 1 is output from the detector 32 to the integration circuit 5.

  The integration circuit 5 outputs an analog integration signal obtained by integrating the detection signal K1 in the integration period, and the A / D converter 6 outputs a signal intensity obtained by converting the integration signal into a digital value. The integration process of the integration circuit 5 is to integrate the power of the detection signal K1, and more specifically, the charge of the detection signal K1 is accumulated in a capacitor, and the charging voltage of the capacitor is output as an integration result. Yes.

  The signal processing unit 7 determines the timing of the integration period based on the digital signal intensity output from the A / D converter 6 so as to be synchronized with the timing of the reception pulse P2 of the detection signal K1, and the phase control unit 8 The integration circuit 5 outputs an integration on / off signal Sg that maintains a high level (hereinafter referred to as the H level) over the integration period, and is at a low level (hereinafter referred to as the L level) during the integration period. When the integration on / off signal Sg is at the H level, the integration process is performed to synchronize the phase of the integration period with the timing of the reception pulse P2. Then, the signal processing unit 7 determines the generation timing of the reception pulse P2 based on the signal strength after synchronization, the pulse P1 of the transmitted pulse signal (that is, the transmitted radio signal), and the detection signal K1 (that is, the received reflection). The distance to the object is calculated from the phase difference (wave phase) with respect to the received pulse P2 (the phase difference for one pulse or the average of the phase differences for a plurality of pulses), and is output as distance information.

  In such a radio wave sensor, the integration time of the integration circuit 5 varies depending on the individual even if the product is the same due to the variation in parts such as ICs used. For example, when the pulse width of the reception pulse P2 of the detection signal K1 is 3 ns and the integration time of the integration circuit 5 is 6 ns, the integration circuit 5 integrates even during the time 3 ns without the reception pulse P2. If noise is mixed in 3 ns for integrating the power other than P2, loss of signal components is caused, and the ranging accuracy is lowered. In addition, when the pulse width of the reception pulse P2 of the detection signal K1 is 3 ns and the integration time of the integration circuit 5 is 2 ns, there is a possibility that sufficient charges may not be accumulated due to the delay of the integration operation of the integration circuit 5, etc. In this case, the signal component is lost, and the ranging accuracy is lowered.

  Therefore, in the present invention, an integration time control unit 9 that adjusts the integration time of the integration circuit 5 is provided, and the phase control unit 8 maintains the H level over the integration period set by the integration time control unit 9. An integration on / off signal Sg is output. Specifically, when the radio wave sensor is shipped, an object having a predetermined size and shape is disposed at a position a predetermined distance from the antenna 2 and a reflected wave from the object is received. Then, as shown in FIGS. 3A and 3B, the inspector observes the waveforms of the detection signal K1 and the integration on / off signal Sg, and manually operates the integration time control unit 9 to perform integration on / off. The time length (integration time) Tg of the H level of the off signal Sg is made to coincide with the pulse width Tp of the reception pulse P2.

  Therefore, even if there is a variation in the characteristics of the integration circuit 5 due to a variation in parts for each lot in the IC to be used, the integration time of the integration circuit 5 is adjusted for each individual radio wave sensor to match the pulse width of the reception pulse P2. As a result, individual differences in distance measurement accuracy can be suppressed, and a decrease in distance measurement accuracy can be prevented. Further, individual differences in distance measurement accuracy due to characteristic variations of the transmission unit 1 and the detection block 3 can be similarly suppressed.

(Embodiment 2)
As shown in FIG. 4, the radio wave sensor of this embodiment is provided with an antenna 10 and a switching unit 11 in the configuration of Embodiment 1 (see FIG. 1), and the same configuration as that of Embodiment 1 is the same. Reference numerals are assigned and description is omitted.

  The switching unit 11 connects the output of the transmission unit 1 to the switching unit 4 or the antenna 10 so as to be switchable, and switching control is performed by the signal processing unit 7. And at the time of normal distance detection, the output of the transmission part 1 is connected to the switch part 4, and the distance measurement operation | movement is performed by using the antenna 2 as transmission / reception common use.

  On the other hand, when adjusting the integration time, the output of the transmitter 1 is connected to the antenna 10, and the antenna 10 is used exclusively for transmission and the antenna 2 is used exclusively for reception. The antenna 10 and the antenna 2 are arranged at a predetermined distance X, and a radio signal transmitted from the antenna 10 is received by the antenna 2 with a phase difference corresponding to the distance X.

  In the present embodiment, the phase control of the integration period by the phase control unit 8 and the integration time control by the integration time control unit 9 can be manually adjusted. First, the inspector performs the steps shown in FIGS. As shown in FIG. 4, the waveforms of the detection signal K1 and the integration on / off signal Sg are observed, and the integration time control unit 9 is manually operated to set the time length (integration time) of the integration on / off signal Sg at the H level. Tg is set to 10 ns, which is sufficiently longer than the pulse width Tp (= 3 ns) of the reception pulse P2, and then the phase controller 8 is manually operated to receive the H level period of the integration on / off signal Sg. The pulse P2 is not overlapped (that is, the phase of the integration period is set to the first phase that does not include the reception pulse P2 in the integration period). At this time, as shown in FIG. 5C, the integration circuit 5 outputs an analog integration signal K2 obtained by integrating components other than the reception pulse P2 of the detection signal K1, and the integration value L1 is the background noise intensity. Represents. Then, the A / D converter 6 outputs a signal intensity obtained by converting the integral value L1 into a digital value, and the inspector monitors this signal intensity. The inspector obtains the background noise intensity (first signal intensity) of the detection signal K1 from the output of the A / D converter 6 by deriving an average obtained by performing the above process once or a plurality of times.

  Next, as shown in FIGS. 6A and 6B, the examiner observes each waveform of the detection signal K1 and the integration on / off signal Sg, and the time length of the integration on / off signal Sg at the H level. While maintaining Tg at 10 ns, the phase controller 8 is then manually operated so that the H level period of the integration ON / OFF signal Sg overlaps the entire period of the reception pulse P2 (that is, the phase of the integration period). Is set to the second phase including the entire reception pulse P2 in the integration period). At this time, as shown in FIG. 6C, the integration circuit 5 outputs an analog integration signal K2 obtained by integrating components including the entire period of the reception pulse P2 of the detection signal K1, and the integration value L2 is It represents the signal intensity including the entire period of the received pulse P2 and the background noise. Then, the A / D converter 6 outputs a signal intensity obtained by converting the integral value L2 into a digital value, and the inspector monitors this signal intensity. The inspector obtains, as a second signal strength, a difference obtained by subtracting the background noise strength of the detection signal K1 from the signal strength derived by performing the above processing once or the signal strength derived from the average of a plurality of repetitions. .

  Next, as shown in FIGS. 7A and 7B, the inspector observes each waveform of the detection signal K1 and the integration on / off signal Sg, and the time length of the H level of the integration on / off signal Sg. While maintaining Tg at 10 ns, the phase controller 8 is then manually operated to change the H level period of the integration on / off signal Sg from the state shown in FIGS. 6A and 6B with respect to the received pulse P2. The signal intensity output from the A / D converter 6 is monitored while shifting in the delay direction (that is, while shifting the phase of the integration period from the second phase toward the delay direction). Then, the inspector integrates the third signal intensity L3 = L2 / 2 at the time when the monitored signal intensity becomes half of the second signal intensity (FIG. 7C). When the period is set), the difference between the second phase and the third phase is detected as the phase shift amount W1 in the integration period.

  Then, the inspector manually operates the integration time control unit 9 to set the time twice as long as the shift amount W1 as the time length Tg of the H level of the integration on / off signal Sg at the time of normal distance detection (that is, Integration time), the integration time matches the pulse width Tp of the reception pulse P2.

  Therefore, even if there is a variation in the characteristics of the integration circuit 5 due to a variation in parts for each lot in the IC to be used, the integration time of the integration circuit 5 is adjusted for each individual radio wave sensor to match the pulse width of the reception pulse P2. As a result, individual differences in distance measurement accuracy can be suppressed, and a decrease in distance measurement accuracy can be prevented. Further, individual differences in distance measurement accuracy due to characteristic variations of the transmission unit 1 and the detection block 3 can be similarly suppressed.

  In the present embodiment, the time twice as long as the shift amount W1 is set as the integration time as described above. However, an appropriate integration time corresponding to the communication environment may be set based on the shift amount W1, For example, by multiplying the shift amount W1 by a predetermined value (1.5 times, 2.5 times, etc.), adding a predetermined value to the shift amount W1, adding a predetermined value to or subtracting the predetermined value from the shift amount W1, etc. An appropriate integration time can be set.

(Embodiment 3)
As shown in FIG. 8, the radio wave sensor of this embodiment is provided with a controller 20 in the configuration of the second embodiment (see FIG. 4). The same components as those of the second embodiment are denoted by the same reference numerals. Description is omitted.

  The controller 20 is connected to the signal control unit 7 and automatically sets the integration time that was manually performed by the inspector in the second embodiment.

  First, as shown in FIGS. 5 (a) and 5 (b), the controller 20 observes each waveform of the detection signal K1 and the integration on / off signal Sg, and remotely operates the integration time control unit 9 to perform integration on. The time length (integration time) Tg of the H level of the / off signal Sg is set to 10 ns, which is sufficiently longer than the pulse width Tp (= 3 ns) of the reception pulse P2, and then the phase controller 8 is remotely operated. Therefore, the H level period of the integration on / off signal Sg is not overlapped with the reception pulse P2 (that is, the phase of the integration period is set to the first phase that does not include the reception pulse P2 in the integration period). . At this time, as shown in FIG. 5C, the integration circuit 5 outputs an analog integration signal K2 obtained by integrating components other than the reception pulse P2 of the detection signal K1, and the integration value L1 is the background noise intensity. Represents. Then, the A / D converter 6 outputs a signal strength obtained by converting the integral value L1 into a digital value, and the controller 20 monitors this signal strength. The controller 20 performs the above process once to derive the signal intensity, or repeats the above process a plurality of times to derive the average of the signal intensity, thereby obtaining the background noise of the detection signal K1 from the output of the A / D converter 6. The intensity (first signal intensity) is acquired.

  Next, as shown in FIGS. 6A and 6B, the controller 20 observes the waveforms of the detection signal K1 and the integration on / off signal Sg, and the time length of the integration on / off signal Sg at the H level. While maintaining Tg at 10 ns, the phase controller 8 is then remotely operated so that the H level period of the integration ON / OFF signal Sg overlaps the entire period of the reception pulse P2 (that is, the phase of the integration period). Is set to the second phase including the entire reception pulse P2 in the integration period). At this time, as shown in FIG. 6C, the integration circuit 5 outputs an analog integration signal K2 obtained by integrating components including the entire period of the reception pulse P2 of the detection signal K1, and the integration value L2 is It represents the signal intensity including the entire period of the received pulse P2 and the background noise. Then, the A / D converter 6 outputs a signal intensity obtained by converting the integral value L2 into a digital value, and the controller 20 monitors this digital value. The controller 20 obtains, as a second signal strength, a difference obtained by subtracting the background noise strength of the detection signal K1 from the signal strength derived by performing the above processing once, or the average value of the derived signal strength repeated a plurality of times. To do.

  Next, as shown in FIGS. 7A and 7B, the controller 20 observes each waveform of the detection signal K1 and the integration on / off signal Sg, and the time length of the H level of the integration on / off signal Sg. With the Tg maintained at 10 ns, the phase control unit 8 is then remotely operated, and the H level period of the integration ON / OFF signal Sg is changed with respect to the reception pulse P2 from the states of FIGS. The signal intensity output from the A / D converter 6 is monitored while shifting in the delay direction (that is, while shifting the phase of the integration period from the second phase toward the delay direction). Then, the controller 20 sets the integration period to the third phase where the third signal intensity L3 = L2 / 2 at the time when the monitor value becomes half the second signal intensity (FIG. 7C). The difference between the second phase and the third phase is detected as the phase shift amount W1 in the integration period.

  Then, the integration time control unit 9 uses the period twice as long as the shift amount W1 as the time length Tg of the H level of the integration on / off signal Sg at the time of normal distance detection (that is, the integration time). Are stored in a non-volatile memory (not shown).

  When the output of the transmission unit 1 is connected to the switching unit 4 and the distance measurement operation is performed with the antenna 2 being used for both transmission and reception, the signal processing unit 7 reads the integration time from the non-volatile memory of the controller 20 and performs the distance measurement. By setting the integration time at the time of operation, the integration time coincides with the pulse width Tp of the reception pulse P2, and high ranging accuracy is realized.

  Therefore, even if there is a variation in the characteristics of the integration circuit 5 due to a variation in parts for each lot in the IC to be used, the integration time of the integration circuit 5 is adjusted for each individual radio wave sensor to match the pulse width of the reception pulse P2. As a result, individual differences in distance measurement accuracy can be suppressed, and a decrease in distance measurement accuracy can be prevented. Further, individual differences in distance measurement accuracy due to characteristic variations of the transmission unit 1 and the detection block 3 can be similarly suppressed. Furthermore, since the controller 20 automatically sets the integration time, the setting work can be simplified and the production efficiency can be improved.

  In the present embodiment, the time twice as long as the shift amount W1 is set as the integration time as described above. However, an appropriate integration time corresponding to the communication environment may be set based on the shift amount W1, For example, by multiplying the shift amount W1 by a predetermined value (1.5 times, 2.5 times, etc.), adding a predetermined value to the shift amount W1, adding a predetermined value to or subtracting the predetermined value from the shift amount W1, etc. An appropriate integration time can be set.

It is a figure which shows the structure of the electromagnetic wave sensor of Embodiment 1. (A) (b) It is a figure which shows a radio signal and a detection signal same as the above. (A) (b) It is a figure which shows the radio signal and integration on / off signal same as the above. It is a figure which shows the structure of the electromagnetic wave sensor of Embodiment 2. (A)-(c) It is a figure which shows the operation | movement at the time of background noise intensity | strength acquisition same as the above. (A)-(c) It is a figure which shows the operation | movement at the time of signal intensity acquisition same as the above. (A)-(c) It is a figure which shows the operation | movement at the time of the integration time setting same as the above. It is a figure which shows the structure of the electromagnetic wave sensor of Embodiment 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Antenna 3 Detection block 4 Switching part 5 Integration circuit 6 A / D converter 7 Signal processing part 8 Phase control part 9 Integration time control part

Claims (2)

Transmits a radio signal composed of pulses generated at a predetermined period, receives a reflected wave reflected when the transmitted radio signal hits an object, and reaches the object based on a phase difference between the transmitted radio signal and the received reflected wave In the radio wave sensor that detects the distance of
Transmitting means for transmitting a radio signal composed of pulses of a predetermined period;
Receiving means for receiving a radio signal transmitted by the transmitting means;
Detecting means for detecting an envelope of the signal received by the receiving means and outputting a detection signal;
Integrating means for integrating the output of the detection means in the integration period and outputting the integrated value;
A phase control means for setting the phase of the integration period relative to the pulse included in the output of the detection means to be variable, and synchronizing the integration period with the pulse;
A / D conversion means for outputting the signal intensity obtained by converting the output of the integration means into a digital signal;
Based on the output of the A / D conversion means, a phase difference between one or more transmitted pulses and one or more pulses of the received reflected wave is detected, and a distance to the object is calculated based on the phase difference. Signal processing means;
An electromagnetic wave sensor comprising: an integration time control means for variably setting an integration time which is the length of an integration period. The receiving means is arranged at a predetermined distance from the transmitting means, receives a radio signal transmitted by the transmitting means,
The phase control means sets the phase of the integration period to a first phase that does not include a pulse in the integration period and measures the first signal intensity, and then sets the phase of the integration period to the entire pulse in the integration period. A second signal strength obtained by subtracting the first signal strength from the measured signal strength set to the second phase including the second phase, and then the phase of the integration period is half of the second signal strength. A controller is provided which sets the third phase at which the third signal intensity is obtained, and then sets the integration time based on the difference between the second phase and the third phase by the integration time control means. The radio wave sensor according to claim 1.

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