DE102012211222B4 - Target information measuring device with high possible accuracy of measured information - Google Patents

Abstract

A target information measurement device, comprising: a transceiver module (10, 10A, 20, 20A) that transmits a plurality of signal pulses and receives a plurality of echoes based on the plurality of signal pulses every predetermined measurement cycle to obtain a plurality of received signals, each having an intensity of a corresponding one of the plurality of echoes represents;a first measurement module (321, 131) that: for each measurement cycle, measures a first elapsed time between a transmission time of a signal pulse in the plurality of signal pulses and a first time, the first time being a time when a level of a received signal accordingly the one signal pulse passes a predetermined threshold level, the received signal being defined as a signal received from the target; andbased on the first elapsed time,acquiring a first measurement representing distance information to a target from the target information measurement device, the target generating an echo based on the one signal pulse corresponding to the signal received from the target;a second measurement module (322,132) that:samples each of the plurality of received signals at predetermined sampling intervals for each measurement cycle to obtain sampled levels for each of the plurality of received signals;extracts multiple sets of sampled levels, the sampled levels of each of the plurality of sets corresponding to the plurality of received signals, respectively, and the sampling instants of the sampled levels of each of the plurality of sets have an identical elapsed time with respect to the transmission timing of a corresponding one of the plurality of signal pulses;integrating the sampled levels of each of the plurality of sets together to obtain a plurality of integrated sampled levels en to obtain, based on the plurality of integrated sampled levels, a second measurement representing the distance information to the target from the target information measuring device;determining means (40, 40A) determining how the first measurement and/or the second measurement becomes the final determining a distance of the target according to a parameter, the parameter having a correlation with an intensity of at least one of the plurality of echoes; and a velocity calculator (40, 40A, S190 to S220) configured to calculate, for each measurement cycle, a velocity of the target according to the final determined distance of the target,wherein the first measurement module is configured to:a first threshold level greater than is a predetermined noise level, and having as the threshold level a second threshold level that is higher than the first threshold level;for each measurement cycle, measuring the first elapsed time between the transmission instant of the one signal pulse and the first instant using the second threshold level as the threshold level if the level of the signal received from the target is higher than the second threshold level; andfor each measurement cycle, when the level of the signal received from the target is equal to or less than the second threshold level, measuring the first elapsed time between the transmission instant of the one signal pulse and the first instant using the first threshold level as the threshold level, andwherein the determining means is configured to use the first measurement when the level of the signal received from the target representing the parameter is higher than the second threshold level to definitively determine the distance of the target to use the second measurement when the level of the from the target received signal representing the parameter is lower than the first threshold level to definitively determine the distance of the target and to use an average of the first measurement and the second measurement when the level of the signal received from the target is equal to or greater than the first threshold level and equal to or less than the second threshold level is to finally determine the distance of the target.

Description

TECHNICAL AREA

The present invention relates to target information measuring devices that transmit signal pulses, receive echoes generated by reflecting the transmitted signal pulses from targets, and based on the received echoes measure information regarding the targets such as the distances between the targets and the devices and the velocities of goals.

BACKGROUND OF THE INVENTION

Target information measuring devices such as a radar device are often used for automobiles, for example, to improve driving safety of the automobiles. A typical type of target information measuring device is intended to transmit pulsed waves and receive echoes of the transmitted waves from targets. The target information measurement device is also provided to measure time differences between the transmission timing of a pulsed wave and the reception timings of echoes of the transmitted pulsed wave, thereby measuring the distances between the echoes associated with the targets and the target information measurement device. Note that the reception timing of an echo represents the timing at which a received signal such as a voltage signal of the echo reaches a maximum signal level such as a maximum voltage level.

• eine erste Zeitdifferenz zwischen dem Übertragungszeitpunkt einer gepulsten Welle und einem ersten Zeitpunkt, wenn ein empfangenes Signal entsprechend einem Echo der übertragenen gepulsten Welle von einem Ziel einen vorbestimmten Grenzwert überschreitet; und
• eine zweite Zeitdifferenz zwischen dem Übertragungszeitpunkt der gepulsten Welle und einem zweiten Zeitpunkt, wenn das empfangene Signal unterhalb den vorbestimmten Grenzwertpegel fällt. Dann schätzt der erste technische Ansatz basierend auf der ersten Zeitdifferenz und der zweiten Zeitdifferenz eine Zeitdifferenz zwischen dem Übertragungszeitpunkt der gepulsten Welle und einen Empfangszeitpunkt des Echos.

There is a first technical approach to measuring time differences between the time of transmission of a pulsed wave and the time of reception of echoes using the corresponding pulsed wave (compare the JP H09 - 236 661 A ). The first technical approach measures individually:

• a first time difference between the time of transmission of a pulsed wave and a first time when a received signal corresponding to an echo of the transmitted pulsed wave from a target exceeds a predetermined threshold; and
• a second time difference between the time of transmission of the pulsed wave and a second time when the received signal falls below the predetermined threshold level. Then, based on the first time difference and the second time difference, the first technique estimates a time difference between the transmission timing of the pulsed wave and a reception timing of the echo.

There is also a second technical approach for measuring time differences between the transmission timing of a pulsed wave and the reception timings of echoes corresponding to the pulsed wave (compare the JP 2005 - 257 405 A ). The second technique transmits pulsed waves and samples a received signal at predetermined intervals according to an echo of each transmitted pulsed wave. The second technique integrates a predetermined number of sampled values each having the same elapsed time from the transmission timing of a corresponding pulsed wave to calculate an integrated sampled value corresponding to a sampled value of an integrated signal; the integrated signal is obtained by integrating the received signals corresponding to the respective transmitted pulse waves. Then, based on the integrated sampled value, the second technique obtains a reception timing of the echo corresponding to each transmitted pulsed wave.

the JP 2004 - 177 350 A discloses an inventive concept for using both the first technical approach and the second technical approach.

On the other hand, there is a technical approach to measuring the difference between a target associated with an echo and a target information measuring device ( WO 2007 - 004 606 A1 and especially their Japanese translated version). This third technical approach has a feature of sampling a received signal corresponding to an echo of a transmitted pulsed wave by first and second different sampling approaches.

The first sampling approach is level sampling for sampling, that is, latching, a level of a binary-coded received signal for each rising edge of a sampling clock. The second sampling approach is edge sampling for sampling, that is, latching, a level of a binary-coded received signal for each rising edge of the binary-coded signal asynchronously to the sampling clock.

In particular, the third technical approach switches between the first sampling approach and the second sampling approach according to a parameter related to the signal-to-noise ratio of a received signal resulting in an echo of a transmitted pulsed wave is associated. That is, the third technique obtains a time difference between the transmission timing of the transmitted pulsed wave and a detection timing of the received signal associated with an echo of the transmitted pulsed wave based on results of sampling of the switched sampling approach.

It will also refer to the U.S. 2003/0 218 919 A1 and the DE 103 56 797 A1 referenced, which have been identified as prior art.

OVERVIEW OF THE INVENTION

The time-differential estimation accuracy of the first technical approach depends on the level of a received signal, that is, the intensity of a corresponding echo of a transmitted pulse wave. For this reason, it may be difficult to estimate with a high accuracy a time difference between the transmission timing of the pulsed wave and a receiving timing of the echo when the received signal level is low, for example, constantly below the threshold.

This problem is solved by the features of the independent claim.

character list

Further aspects of the present invention will become apparent from the following detailed description of an embodiment with reference to the drawings.

• 1 ein Blockschaltbild, das schematisch ein Beispiel der Gesamtstruktur einer Zielinformationsmessvorrichtung gemäß einer ersten Ausführungsform der vorliegenden Erfindung illustriert;
• 2 ein Zeitablaufsdiagramm, das schematisch ein Beispiel von Betriebszeitpunkten beziehungsweise Zeitgebungen von Komponenten der Zielinformationsmessvorrichtung mit Bezug auf Messzyklen illustriert;
• 3A eine Ansicht, die schematisch im Beispiel von Operationen einer ersten Messschaltung, die in 1 illustriert ist, und ein Beispiel von Operationen einer zweiten Messschaltung illustriert, die in 1 illustriert ist;
• 3B eine Ansicht, die schematisch ein Beispiel illustriert, wie integrierte abgetastete Pegel durch die zweite Messschaltung zu erzeugen sind;
• 3C eine Ansicht, die schematisch ein alternatives Beispiel von Operationen der ersten Messschaltung, die in 1 illustriert ist, und ein alternatives Beispiel von Operationen der zweiten Messschaltung illustriert, die in 1 illustriert ist;
• 4 einen Graphen, der schematisch ein Beispiel von Beziehungen zwischen den Pegeln empfangener Signale und den Genauigkeitspegeln der ersten Messung und der zweiten Messung illustriert, die durch die entsprechende erste Messschaltung und entsprechende zweite Messschaltung erlangt werden;
• 5 eine Ansicht, die schematisch ein Beispiel illustriert, wie der Pegel eines empfangenen Signals unter beziehungsweise zwischen den Bereichen in dem Graphen 4 variiert;
• 6 ein Ablaufdiagramm, das schematisch ein Beispiel spezifischer Operationen eines Signalbearbeitungsmoduls illustriert, das in 1 illustriert ist, um einen Zielerfassungstask beziehungsweise eine Zielerfassungsaufgabe durchzuführen;
• 7 eine Ansicht, die schematisch illustriert, wie eine erste Abstandsmessung und/oder eine zweite Abstandsmessung durch die erste und zweite Messschaltung gemessen werden, und wie Abstandsdaten für jeden Messzyklus gemäß der ersten Ausführungsform berechnet werden;
• 8 eine Ansicht, die schematisch illustriert, dass Echos von unterschiedlichen Zielen sich in ihrer Intensität voneinander abhängig von den Abständen der unterschiedlichen Ziele und ihren Typen unterscheiden;
• 9 eine Ansicht, die schematisch illustriert, dass verstärkte empfangene Signale eine gesättigte Wellenform aufweisen können;
• 10 ein Blockschaltbild, das schematisch ein Beispiel der Gesamtstruktur einer Zielinformationsmessvorrichtung gemäß einer zweiten Ausführungsform der vorliegenden Offenbarung illustriert;
• 11 ein Graph, der schematisch die Zeitlängen der entsprechenden empfangenen Signale, die einen Grenzwertpegel überschreiten, gemäß der zweiten Ausführungsform illustriert;
• 12 ein Ablaufdiagramm, das schematisch ein Beispiel spezifischer Operationen eines Signalverarbeitungsmoduls illustriert, das in 7 illustriert ist, um einen Abstandsinformationsauswahltask beziehungsweise eine Abstandsinformationsauswahlaufgabe durchzuführen;
• 13 ein Blockschaltbild, das schematisch ein Beispiel eines Teils einer Zielinformationsmessvorrichtung gemäß einer dritten Ausführungsform der vorliegenden Erfindung illustriert; und
• 14 einen Graphen, der schematisch die Gradienten entsprechend empfangener Signale gemäß der dritten Ausführungsform illustriert.

Show it:

• 1 12 is a block diagram schematically illustrating an example of the overall structure of a target information measurement device according to a first embodiment of the present invention;
• 2 12 is a timing chart that schematically illustrates an example of operation timings of components of the target information measurement device with respect to measurement cycles;
• 3A a view schematically showing in example operations of a first measurement circuit shown in FIG 1 is illustrated, and illustrates an example of operations of a second measurement circuit shown in FIG 1 is illustrated;
• 3B 12 is a view schematically illustrating an example of how to generate integrated sampled levels by the second measurement circuit;
• 3C a view schematically showing an alternative example of operations of the first measurement circuit shown in FIG 1 is illustrated, and illustrates an alternative example of operations of the second measurement circuit shown in FIG 1 is illustrated;
• 4 12 is a graph that schematically illustrates an example of relationships between the received signal levels and the accuracy levels of the first measurement and the second measurement, which are obtained by the corresponding first measurement section and the corresponding second measurement section;
• 5 12 is a view schematically illustrating an example of how the level of a received signal is between the areas in the graph 4 varies;
• 6 a flowchart schematically illustrating an example of specific operations of a signal processing module included in 1 is illustrated to perform a target acquisition task;
• 7 12 is a view schematically illustrating how a first distance measurement and/or a second distance measurement is measured by the first and second measurement circuits and how distance data is calculated for each measurement cycle according to the first embodiment;
• 8th a view schematically illustrating that echoes from different targets differ in intensity from each other depending on the distances of the different targets and their types;
• 9 a view schematically illustrating that amplified received signals may have a saturated waveform;
• 10 12 is a block diagram schematically illustrating an example of the overall structure of a target information measurement device according to a second embodiment of the present disclosure;
• 11 12 is a graph schematically illustrating time lengths of respective received signals exceeding a threshold level according to the second embodiment;
• 12 a flowchart schematically illustrating an example of specific operations of a signal processing module included in 7 is illustrated to perform a distance information selection task;
• 13 Fig. 12 is a block diagram showing schematically an example of part of a target information meter apparatus according to a third embodiment of the present invention; and
• 14 14 is a graph schematically illustrating gradients of respective received signals according to the third embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT OF THE INVENTION

Embodiments of the invention are explained below with reference to the drawings. In this embodiment and its modifications, like parts assigned like reference numerals are omitted or simplified to avoid redundant description.

First embodiment

A target information measuring device to which the present invention is applied as a first embodiment of the present invention will be explained below. The target information measuring device 1 is installed in a motor vehicle MV. The target information measuring device 1 is provided to detect different targets in front of the motor vehicle MV and generate information associated with the different targets. The information includes the distances between the different targets in relation to the motor vehicle (device 1) and the speeds of the different targets relative to the motor vehicle MV.

In particular, according to 1 the target information measuring device 1 consists of a transmission module 10, a receiving module 20, a distance measuring module 30 and a signal processing module 40.

The transmission module 10 is placed, for example, on the center of the front end (front) of the motor vehicle MV and is provided to transmit laser beams pulsed according to a transmission timing signal ST, that is, laser pulses, to a predetermined target region in front of the motor vehicle MV. For example, the target region has a rectangular shape orthogonal to the traveling direction of the motor vehicle MV.

The receiving module is provided for receiving echoes from targets each of which has reflected a transmitted laser pulse and converting the received echoes into electrical signals as received signals. Each of the electrical signals has a level dependent on the intensity of a corresponding received echo.

The distance measurement module 30 is provided to generate the transmission timing signals ST to provide the transmission timing signals ST to the transmission module 10 and designed to receive the received signals provided by the reception module 20 . The distance measurement module 30 is also provided to measure the distances of the targets with respect to the motor vehicle MV based on the received signals. Each of the targets reflected a corresponding transmitted laser wave.

The signal processing module 40 is provided to detect the targets using the distances of the targets measured by the distance measuring module 30 and generate information related to the targets, such as the distances of the targets to the motor vehicle MV and the relative speeds of the targets to the motor vehicle MV. The information, i.e. target information, generated by the signal processing module 40 is transmitted to at least one ECU installed in the motor vehicle MV, and the target information is used by different application programs or application programs of the at least one ECU for different controls of the motor vehicle MV used.

A structural example of each of the modules 10, 20 and 30 will be explained below.

According to 1 For example, the transmission module 10 consists of a light-emitting element 11 such as a light-emitting diode, and an optical system 12. The light-emitting element 11 emits laser pulses according to the transmission timing signal ST input to the light-emitting element from the measurement module 30. The optical system 12 is designed to expand at least the width of each laser pulse transmitted from the light emitting element 11 . The width is parallel to the width direction (horizontal direction) of the motor vehicle MV. This allows the laser pulses each having a width expanded in the vehicle width direction to scan the target region in front of the vehicle MV.

The reception module 20 consists of a condenser lens 21, a plurality of reception elements 22 and a plurality of amplifiers 23. In this embodiment, four reception elements 22a1 to 22a4 are aligned in a row parallel to the width direction of the motor vehicle MV. That is, the four receiving elements 22a1 to 22a4 are arranged to receive echoes arriving in different directions (azimuths) on a horizontal plane of the target region.

In addition, each receiving element 22 is a well-known image sensor composed of, for example, a photodetector such as a CMOS element or a CCD, and amplifiers 23 are provided for the respective receiving elements 22, so the amplifiers 23 are referred to as amplifiers 23a1 to 23a4.

For example, the condenser lens 21 has a light-receiving surface with a size corresponding to the size of the target region and works to receive echoes incident on the light-receiving surface from the target region and to concentrate the echoes of the respective receiving elements 22a1 to 22a4. For example, a plurality of portions of the target region correspond to the receiving elements 22a1 to 22a4, respectively, and the echoes from the portions of the target region are received by the receiving elements 22a1 to 22a4, respectively.

Each of the receiving elements 22a1 to 22a4 is provided to receive a corresponding echo condensed by the condenser lens 21 and generate a received signal having a voltage level depending on the intensity of a corresponding echo.

Each of the amplifiers 23a1 to 23a4 is provided to amplify a received signal output from a corresponding one of the receiving elements 22a1 to 22a4 and provide the distance measuring module 30 with an amplified received signal.

Hereinafter, a pair of a receiving element 22ai (i = 1, 2, 3 or 4) and a corresponding amplifier 23ai is referred to as a receiving channel CHi (i = 1, 2, 3 or 4). That is, an amplified received signal output from a corresponding receiving channel CHi is provided to the distance measurement module 30 as a received signal Ri.

The distance measuring module 30 consists of a control unit 31 and four distance measuring circuits 32a to 32d provided for the respective receiving channels CH1 to CH4.

The control circuit 31 is provided to generate the transmission timing signal ST. Each of the distance measurement circuits 32a to 32d is arranged to generate, based on a corresponding received signal Ri and the transmission timing signal ST, a first measurement of a distance to a target corresponding to the received signal Ri using a first technical approach explained later. Each of the distance measurement circuits 32a to 32d is also arranged to generate, based on a received signal Ri and the transmission timing signal ST, a second distance measurement to a target corresponding to the received signal Ri using a second technical approach explained later. Note that since the distance measuring circuits 32a to 32d are identical in structure to each other, one of the distance measuring circuits 32a to 32d is referred to as a distance measuring circuit 32 when it is not necessary to distinguish between the distance measuring circuits 32a to 32d.

In particular, according to 2 , the control circuit 31 generates a periodic signal consisting of regular pulses with a constant period, i.e. a constant cycle Tcycl of, for example, 33 milliseconds. The cycle Tcycl of the periodic signal is hereinafter referred to as a measurement cycle Tcycl. The circuit 31 generates a set of a predetermined number of N pulses of the transmission timing signal ST each time a pulse of the periodic signal is generated. In this embodiment, the predetermined number N is set to 100, that is, 100 pulses of the transmission timing signal ST are generated from the control circuit 31 in each measurement cycle Tcycl. A constant interval Tw between each pair of adjacent pulses of the transmission timing signal ST is set to be sufficiently longer than a maximum measurement period required for a laser pulse to propagate to and from a predetermined distance measured by the device 1 is detectable. For example, in this embodiment, the limit of the distance detectable by the device 1 is set to 50 m, the maximum measurement period is set to 0.33 µs, and the constant interval Tw between each pair of adjacent transmission timing signals ST is set to 18 µs. It should be noted that the measurement cycle Tcycl, the number N of pulses of the transmission timing signal ST for each measurement cycle Tcycl, and the constant interval Tw are not limited to the respective values explained above, and can be set to any values as long as the Values satisfy the following comparison equation or inequality: Tcycl > N x Tw.

According to 1 a distance measurement circuit 32 consists of a first measurement circuit (single-scan distance measurement circuit) 321 and a second measurement circuit (integral distance measurement circuit) 322. The first measurement circuit is provided to perform a first distance measurement task according to the first technical approach using one of the N-pulses such as to perform the fiftieth pulse, which is at everyone Measurement cycle Tcycl is entered to generate the first distance measurement to a target according to received signals Ri. The second measurement circuit 322 is arranged to perform a second distance measurement task according to the second technique using all of the N input pulses at each measurement cycle Tcycl to generate the second distance measurement to a target according to a received signal Ri. The first distance measurement to a target corresponding to a received signal Ri is referred to below as the first distance measurement and the second distance measurement to a target corresponding to received signals Ri is referred to below as the second distance measurement.

Each of the first and second measurement circuits 321 and 322 is arranged to activate continuously so that the first distance measurement and the second distance measurement are both output to the signal processing module 40 at each measurement cycle Tcycl.

For example, according to 1 the first measurement circuit 321 composed of a comparator 321a, a timer 321b and a calculator 321c and the components 321a, 321b and 321c are designed to carry out the first distance measurement task cooperatively with each other. This structural example of the first measurement circuit 321 is disclosed in Japanese Patent Application Publication No JP H09 - 236 661 A1 , discussed above, whose assignee is identical to that of this application.

According to 3A the comparator 321a holds a predetermined threshold level, that is, a voltage level and receives a received Ri corresponding to a laser pulse in response to the fiftieth pulse of the transmission timing signal ST and compares the level of the received signal Ri with the threshold level. The comparator 321a generates a first timing when the level of the received signal Ri exceeds the threshold level, that is, passes the threshold level for the first time, and a second timing when the level of the received signal Ri falls below the threshold level, that is, that next time passes the limit level. The comparator 321a outputs both the first timing and the second timing to the timer 321b.

The timer 321b receives each pulse of the transmission timing signal ST as the transmission timing of a corresponding laser pulse and the first timing and the second timing. The timer 321b also measures a first elapsed time Tf1 between the transmission timing of a laser pulse corresponding to the received signal Ri and the first timing, and measures a second elapsed time Tb1 between the transmission timing of the laser pulse corresponding to the received signal Ri and the second timing.

The calculator 321c defines the center of the first timing and the second timing as a received timing at which the received signal Ri peaks. Then, the calculator 321 calculates an average value of the first and second elapsed times Tf1 and Tb1 as an elapsed time Tr1 between the transmission timing and the received timing. The elapsed time Tr1 is given by the following equation: Tr1=(Tf1+Tb1)/2 given. Subsequently, the calculator 321c converts the elapsed time Tr1 into a distance value to a target according to the received signal Ri and outputs the value of the distance or the distance value to the signal processing module 40 as a first distance measurement D1.

As a single structural example of the first measurement circuit 321 according to this embodiment, a first threshold level and a second threshold level higher than the first threshold level are provided as the threshold level, and first to fourth timers 321b1 to 321b4 are provided as the timer 321b . Each of the first to fourth timers 321b1 to 321b4 starts counting up a digital count value from its initial value 0 at each period of an operation clock provided by the control circuit 31, for example. That is, the update period of the LSB (Least Significant Bit) of the digital count of each of the first to fourth timers 321b1 to 321b4 is identical to the period of the operation clock. The update period of the LSB of the digital count value of each of the first to fourth timers is set to 0.125 nanoseconds, for example.

The first timer 321b1 stops counting up the digital count value when the level of a corresponding received signal Ri lower than the first threshold level exceeds the first threshold level. The second timer 321b2 stops counting up the digital count value when the level of a corresponding received signal Ri lower than the second threshold level exceeds the second threshold level. The third timer 321b3 stops counting up the digital count value when the level of a corresponding received signal Ri higher than the second threshold level falls below the second threshold level. The fourth timer 321b4 stops counting up of the digital count when the level of a corresponding received signal Ri higher than the first threshold level falls below the first threshold level.

For example, when the maximum level of a corresponding received signal Ri exceeds the second threshold level, the calculation unit 321c calculates a first distance measurement using the timed digital count of the second timer 321b2 representing the first elapsed time Tf1 and the timed digital count of the third timer 321b3 representing the second elapsed time Tb1.

Otherwise, if the maximum level of a corresponding received signal Ri is higher than the first threshold level and lower than the second threshold level, the calculation unit 321c calculates a first distance measurement D1 using the stopped digital count of the first timer 321b1 representing the elapsed time Tf1 and of the timed digital count of the fourth timer 321b4 representing the second elapsed time Tb1. Furthermore, when the maximum level of a corresponding received signal Ri is equal to or lower than the first threshold level, the calculation unit 321c outputs a first distance measurement D1 of zero.

Note that the calculator 321c may correct the elapsed time Tr1 before conversion into a first distance measurement D1 according to the length of a period during which a received signal Ri exceeds the threshold level. This can determine the elapsed time Tr1 with respect to a disturbance in the waveform of a received signal Ri. The interference is caused in a received signal Ri when the output of a corresponding amplifier saturates.

A structural example of the second measurement circuit 322 for performing the second distance measurement task is disclosed in Japanese Patent Application Publication No. discussed above 2005-257405 disclosed, whose assignee is identical to that of the present application.

For example, the second measurement circuit 322 is designed to sample a received signal Ri corresponding to the respective N pulses of the transmission timing signal ST at predetermined sampling intervals Tsmpl during the lapse of the maximum measurement period from the transmission timing of a corresponding pulse of the transmission timing signal ST. Note that N is an integer equal to or greater than 2. For example, the sampling intervals Tsmpl are set to 25 nanoseconds. Note that the N received signals Ri are hereinafter referred to as a first received signal Ri1, a second received signal Ri2, ... and an Nth received signal RiN.

According to 3B the second measurement section 332 is also designed to extract first to M-th sets of sampled levels in all of the sampled levels. The sampled levels of each of the first through M-th sets correspond to the first through N-th received signals Ri1 through RiN, respectively, and the sampling timings of the sampled levels of each of the first through M-th sets have an identical elapsed time with respect to the transmission timing of a corresponding one pulses of the transmission timing signal ST. In other words, the sampling timings of the sampled levels of each of the first to M-th sets are apparently identical to each other with respect to a reference transmission timing (cf 3B ). Note that M is an integer equal to or greater than 2. In addition, the first through the M-th sets of sampled levels are temporarily aligned at the sampling intervals Tsmpl.

The second measurement circuit 332 is further designed to integrate the sampled levels of each of the first through M-th sets with each other to obtain first through M-th integrated sampled levels for the respective first through M-th sets (cf 3B ).

In addition, the second measurement circuit 332 is designed to determine a threshold level by multiplying the peak level in all of the first to M-th integrated sampled levels by a predetermined coefficient. The coefficient is greater than 0 and less than 1. In this embodiment, the second measurement circuit 332 determines the threshold value by multiplying the peak level in all of the first through Mth integrated sampled levels by 0.5. The threshold level is called the 50% threshold level because the ratio of the threshold level to the peak level can be expressed as 50%.

$$\text{Tb}2=\text{Mb}\times \text{Tsmpl}$$

The second measurement circuit 332 is provided to measure a first timing and a second timing of a discrete received signal Ri composed of the first through M-th integrated sampled levels for the respective first through M-th sets using the threshold level in the same approach as in the case of the first measuring circuit 331 explained above. Then the second measurement circuit 332 is designed to identify which number of the integrated sampled level in the discrete received signal Ri of the first timing and the second timing. An integrated sampled level in the discrete signal corresponding to the first timing is referred to as an Mf-th sampled level, and an integrated sampled level in the discrete received signal Ri corresponding to the second timing is referred to as an Mb-th sampled level (cf 3C ). Then, the second measurement section 332 is provided to calculate a first elapsed time Tf2 between the reference transmission timing and the first timing, and measures a second elapsed time Tb2 between the reference transmission timing and the second timing according to the following equations (1) and (2): $$\text{tf}2=\text{Mf}\times \text{Tsmpl}$$

$$\text{TB}2=\text{mb}\times \text{Tsmpl}$$

Then, the second measuring circuit 332 is provided to calculate an elapsed time Tr2 between the reference transmission timing and the received timing as the middle of the first timing and the second timing using the first and second elapsed times Tf2 and Tb2 with the same approach as the first measuring circuit 331 calculate. Then, the second measurement circuit 332 is provided to convert the elapsed time Tr2 into a distance value to a target according to the received signals Ri1 to RiN, and outputs the distance value to the signal processing module 40 as a second distance measurement D2. In particular, the second measurement circuit 332 is arranged to stop the second distance measurement task as described above if at least one of the received signals Ri1 to RiN exceeds the second threshold level provided in the first measurement circuit 321, resulting in a second distance measurement D2 of zero is issued. This aims to prevent degradation of the accuracy of second distance measurements D2 obtained by the second measurement circuit 332 due to an excess of at least one integrated sampled level over a measurable voltage level range predetermined for the second measurement circuit 332.

• den Pegeln empfangener Signale, das heißt, den Intensitäten entsprechender Echos;
• den Genauigkeitspegeln erster Abstandsmessungen basierend auf den empfangenen Signalen und erlangt durch die erste Messschaltung 321 einer Abstandsmessschaltung;
• den Genauigkeitspegeln zweiter Abstandsmessungen basierend auf den empfangenen Signalen und erlangt durch die zweite Messschaltung 322 einer Abstandsmessschaltung 32;
• dem ersten Grenzwertpegel; und
• dem zweiten Grenzwertpegel illustriert.

4 is a graph that schematically shows relationships between:

• the levels of received signals, that is, the intensities of corresponding echoes;
• the accuracy levels of first distance measurements based on the received signals and obtained by the first measuring circuit 321 of a distance measuring circuit;
• the accuracy levels of second distance measurements based on the received signals and obtained by the second measurement circuit 322 of a distance measurement circuit 32;
• the first threshold level; and
• illustrated at the second threshold level.

Note that in this embodiment, the first threshold level used by the first measurement circuit 321 is fixed at a voltage of 100 mV. The first threshold level of 100 mV can be obtained by adding a predetermined tolerance level to an average noise level of the received signals. In addition, the second threshold level is set at a voltage of 100 mV. The second threshold level of 500 mV can be determined such that the accuracy levels of the first distance measurements obtained by the first measurement circuit 321 are higher than those of the second measurements obtained by the second measurement circuit 322 .

As in 4 1, the first distance measurements are obtained by the first measuring circuit 321 when the levels of the respective received signals, i.e. the intensities of respective echoes, are higher than the first threshold level, and the accuracy levels of the first distance measurements are increased with increasing intensities of respective echoes. Furthermore, the accuracy levels of the second distance measurements obtained by the second measurement circuit 322 become low when the intensities of corresponding echoes are so high that the output of the corresponding amplifier 23 saturates or is so low as to be lower than the average level received signals is.

Hereinafter, in the graph, an area where the intensities of echoes are lower than the average noise level is referred to as an undetected area, and an area where the intensities of echoes are higher than the first threshold level is referred to as a first effective area . Similarly, in the graph, an area where the intensities of echoes are higher than the average noise level and lower than the second threshold level is referred to as a second effective area, and an area where the first effective area and the second effective area overlap is referred to as an intermediate area.

In particular, no first and second distance measurements are obtained when the intensities of echoes are within the undetected range (compare X in 4 ). Second distance measurements are obtained only when the intensities of corresponding echoes are within the second effective range excluding the intermediate range, since the first distance measuring task is stopped in the second effective range (see A in 4 ). The accuracy levels of the first distance measurements are higher than those of the second distance measurements when the intensities of corresponding echoes are within the first effective range excluding the intermediate range (compare C in 4 ). The accuracy levels of the second distance measurements are higher than those of the first distance measurements when the intensities of corresponding echoes are within the intermediate range (compare B in 4 ).

For these reasons, when received signal levels Ri are within the undetected range A equal to or less than the first threshold level, corresponding second distance measurements obtained by the second measurement circuit 322 are only transmitted to the signal processing module 40 as measured data . This situation of the target information measurement device 1 represents that the target information measurement device 1 is in a mode in which the second measurement circuit 322 is used only for distance measurement.

When the received signal levels Ri are within the range C equal to or greater than the second threshold level, corresponding first distance measurements obtained by the first measurement circuit 321 using the second threshold level are only transmitted to the signal processing module 40 as measured data . This situation of the target information measurement device 1 represents that the target information measurement device 1 is in a mode in which the first measurement circuit 321 is used only for distance measurement.

When the received signal levels Ri are within the range B, which is greater than the first threshold level and smaller than the second threshold level, corresponding first distance measurements obtained by the first measurement circuit 321 using the first threshold level and corresponding second distance measurements, obtained by the second measurement circuit 322 to the signal processing module 40 as measured data transmission. This situation of the target information measurement device 1 represents that the target information measurement device 1 is in a mode in which the first and second measurement circuits 321 and 322 are both used for distance measurement.

The mode of the device 1, in which the first measuring circuit 321 is used only for distance measurement, represents an example of the first mode of the device 1. The mode of the device 1, in which the first and second measuring circuits 321 and 322 are both used for distance measurement, represents an example of the second mode of the device 1. The mode in which the second measurement circuit 322 is used only for distance measurement represents an example of the third mode of the device 1.

Furthermore, when the levels of received signals Ri are within the range X such that first and second distance measurements are not obtained, the device 1 is in a mode in which no distances are measured. The mode is referred to as an example of the fourth mode of the device 1. FIG. When the levels of the received signals Ri are within any range except range X such that first and second distance measurements are measurable, i.e. detectable, the device 1 is in a distance-detectable mode. The mode is referred to as an example of the fifth mode of the device 1. FIG.

Note that the level of a received signal Ri, that is, the intensity of a corresponding echo, is not limited to being continuous between adjacent two areas in all of the areas in the graph of FIG 4 to vary.

5 illustrates how the level of a received signal Ri, i.e. the intensity of a corresponding echo, varies between regions A, B, C and X of the graph. In particular, as in 5 1, the level of a received signal Ri varies greatly from area A to area C, that is, the mode of the device 1 is switched from the third mode to the first mode. Similarly, the level of a received signal Ri varies greatly from area C to area A, that is, the mode of the device 1 is switched from the first mode to the third mode.

Why the level of a received signal Ri varies greatly will be explained below.

For example, when the device 1 aims to acquire information about a motor vehicle that is a target, the intensity of an echo varies depending on where a transmitted laser pulse corresponding to the echo is reflected from the motor vehicle. That is, the intensity of an echo when a transmitted laser pulse corresponding to the echo is reflected from the vehicle body differs from that of an echo when a transmitted laser pulse corresponding to the echo is reflected by a reflector attached to the body of the motor vehicle. In addition, the relative spatial relationship between the motor vehicle MV and a target motor vehicle often varies depending on their behaviors such as their speeds, steering operations, vibrations, etc., resulting in frequent variations in the positions of the target motor vehicle that has reflected echoes. For these reasons, there are large variations in the level of a received signal Ri.

According to 1 For example, the signal processing module 40 is provided as an ordinary microcomputer circuit composed of, for example, a CPU 40a, a storage medium 40b including volatile and non-volatile memory, an IO (input and output) interface, etc. The normal microcomputer circuit in this embodiment is defined to include at least a CPU and a main memory such as the storage medium.

The CPU 40a of the signal processing module 40 is designed to carry out at least one target acquisition task using measured data, i.e. a first distance measurement D1 and/or a second distance measurement D2, in accordance with a corresponding program PR1 stored in the storage medium 40b, wherein the measured data are provided from each of the reception channels CHi, thereby detecting a target in front of the motor vehicle MV and information about the detected target such as the distance between the detected target and the motor vehicle MV and the relative speed between them.

6 Figure 12 illustrates schematically specific operations, i.e. steps of the CPU 40a in the target acquisition task are explained in detail below. It should be noted that the CPU 40a activates the program PR1 to start the target detection task every time measured data acquired by the distance measuring circuit 32 is provided to the CPU 40a for each reception channel CHi. In other words, the CPU 40a activates the program PR1 to start the target acquisition task for every measurement cycle Tcycl.

Upon activating the program PR1, the CPU 40a selects a channel CHi (i=1, 2, 3 or 4) from the channels CH1 to CH4. The selected channel CHi has not been subjected to the following operations S120 to S160 and acquires measured data provided from the selected reception channel CHi in step S110.

Next, in step S120, the CPU 40a determines whether the first distance measurement D1 has been calculated as the measured data obtained in step S110, in other words, whether the distance measurement D1 is not zero. If it is determined that the first distance measurement D1 has been calculated as the measured data obtained in step S110 (YES in step S120), the CPU 40a determines in step S130 whether the second distance measurement D2 has been calculated as the measured data obtained in step S110 are obtained is calculated, in other words, whether the second distance measurement D2 in step S130 is non-zero. Similarly, when it is determined that the first distance measurement D1 has not been calculated as the measured data obtained in step S110 (NO in step S120), the CPU 40a determines in step 135 whether the second distance measurement D2 is the measured data , obtained in step S135 have been calculated, in other words, whether the second distance measurement D2 in step S135 is non-zero.

If it is determined that the first distance measurement D1 has been calculated as the measured data obtained in step S110 but the second distance measurement D2 has not been calculated as the measured data (YES in step S120 and NO in step S130), the CPU determines 40a in step S140 that the mode of the device 1 is the first mode. Then, in step S170, the CPU 40a determines that the first distance measurement D1 has been selected as the distance data D for the selected channel CHi in step S140, and then proceeds to step S170.

wobei α eine Richtung des gewichteten Durchschnitts ist.If it is determined that the first distance measurement D1 and the second distance measurement D2 have been calculated as the measured data obtained in step S110 (YES in each of steps S120 and S130), the CPU 40a determines in step S150 that the mode of the device 1 is the second mode. Then, in step S150, the CPU 40a determines distance data D of the selected channel CHi as a weighted average of the measurements D1 and D2 according to the following equation (3): $$\text{D}=\left(1-\mathrm{a}\right)\times \text{<figure-callout id="1" label="D" filenames="DE102012211222B4\_0006.png" state="{{state}}">D</figure-callout>}1+\mathrm{a}\times \text{D}2$$

where α is a weighted average direction.

Thereafter, the CPU 40a proceeds to step S170.

In this embodiment, α is set to 0.3 within a range greater than 0 and less than 1. The weight α can be set to a value dependent on the accuracy levels of the first and second distance measurements D1 and D2 in the intermediate region. at for example, the weight α may be set to a value less than 0.5 if the first distance measurement D1 is greater in accuracy level than the second distance measurement D2, and may be set to a value greater than 0.5 if the second distance measurement D2 is greater than the first distance measurement D1 in terms of its level of accuracy. That is, in this embodiment, the weight α is set to 0.3 when the first distance measurement D1 is two times greater in accuracy level than the second distance measurement D2.

If it is determined that the first distance measurement D1 has not been calculated as the measured data obtained in step S110 but the second distance measurement D2 has been calculated as the measured data (NO in step S120 and YES in step S135), the CPU determines 40a at step S160 that the mode of the device is the third mode. Then, in step S160, the CPU 40a determines that the second distance measurement D2 as the distance data D of the selected channel CHi and proceeds to step S170.

That is, the distance data D is calculated based on the first distance measurement D1 and/or the second distance measurement D2.

On the other hand, when it is determined that the first distance measurement D1 and the second distance measurement D2 are both zero (NO in each of steps S120 and S135), the CPU 40a determines in step S160 that the mode of the device 1 is the fourth mode. Then, without calculating the distance data D, the CPU 40a proceeds to step S170.

In step S170, the CPU 40a stores information indicating the mode of the device 1 in determining the distance data D in the storage unit 40b. Specifically, the CPU 40a stores in the storage unit 40b information indicative of the first mode when the distance data D is determined in step S140, and stores in the storage unit 40b information indicative of the second mode when the distance data D is determined in step S150 . In addition, the CPU 40a stores in the storage unit 40b information indicative of the third mode when the distance data D is determined in step S160, and stores in the storage unit 40b information indicative of the fourth mode when no distance data D in either of the step S140 are calculated up to S160.

Next, at step S180, the CPU 40a determines whether it has performed the operations from step S120 to step S170 for all the reception channels CH1 to CH4. If it is determined that the CPU 40a has not performed the operations from step S120 to S170 for at least one reception channel (NO in step S180), the CPU 40a performs the operations from step S120 to step S170 for the at least one reception channel from the selected channel CHi and executes the determination of step S180.

Thereafter, when it is determined that the CPU 40a has performed the operations from step S120 to step S170 for all reception channels CH1 to CH4 (YES in step S180), the CPU 40a proceeds to step S190.

In step S190, the CPU 40a performs cluster analysis or group analysis of pieces of distance data D determined for the respective channels CH1 to CH4 to group the pieces of distance data into at least one cluster so that when pieces of distance data which are in the same cluster, they are identical to each other.

As a result of the cluster analysis, the CPU 40a determines the at least one cluster as the at least one target to be detected, and determines the distance between the at least one target and the device 1 using at least one piece of distance data D corresponding to the at least one target in step S190. Moreover, in step S190, the CPU 40a determines, as the mode information of the device 1, the information indicating a corresponding one of the first to third modes.

Specifically, when a cluster including a piece of distance data D corresponding to a single receiving channel Ri is detected as a target, the CPU 40a determines as the distance between the target and the device 1 at step S190 the piece of distance data D corresponding to the single receiving channel Ri. Moreover, as the mode information of the device 1, the CPU 40a determines one of the first to fourth modes associated with the piece of distance data D corresponding to the single reception channel Ri in step S190.

On the other hand, when a cluster including pieces of distance data D corresponding to a plurality of reception channels Ri is detected as a same target, the CPU 40a determines as the distance between the same target and the device 1 one of the pieces of distance data D in step S190 according to the following approach.

Especially in this embodiment, the accuracy of distance data D is predetermined depending on which of the first to third mode was used to obtain the distance data D. That is, the accuracy of the distance data D according to the first mode is higher than that of the distance data D according to the second mode, and the accuracy of the distance data D according to the second mode is higher than that of the distance data D according to the first mode.

The CPU 40a compares the accuracies of the pieces of distance data D of a same target corresponding to a plurality of reception channels Ri with each other according to the respective modes corresponding to the pieces of distance data D. As a result of the comparison, the CPU 40a determines at step S190 as the distance between the same target and of the device 1 a piece of distance data D corresponding to the highest accuracy mode among all the modes of the pieces of distance data D. In addition, as the mode information of the device 1, the CPU 40a determines the highest mode and stores the mode information of the device 1 in the storage unit 40b Step S190.

Note that, as described above, the CPU 40a repeatedly performs the target detection task for every measurement cycle Tcycl. For this reason, when the operation in step S190 is completed in a current measurement cycle, the mode information of the device 1 in the previous measurement cycle has been stored in the storage unit 40b (see step S230 explained later). The device 1 mode information stored in a current measurement cycle is referred to as the current device 1 mode, and the device 1 mode information stored in a previous measurement cycle is referred to as the previous device 1 mode.

After step S190, the CPU 40a determines at step S120 whether the mode transition of the device 1 from the previous mode for at least one target to the current mode for the same target is a specific mode transition from the first mode to the third mode or from the third mode to the first mode.

If it is determined that the mode transition of the device 1 from the previous mode for at least one target to the current mode for the same target is not a specific mode transition from the first mode to the third mode or from the third mode to the first mode (NO in step S200), the CPU drives 40a proceeds to step S210. Otherwise, if it is determined that the mode transition of the device 1 from the previous mode for at least one target to the current mode for the same target is a specific mode transition from the first mode to the third mode or from the third mode to the first mode (YES in step S200), the CPU 40a proceeds to step S220.

In step S210, the CPU 40a determines that the distance between a corresponding at least one target and the device 1 measured as an observation in step S190 has a normal reliability level with respect to a reference reliability level. Then, in step S210, the CPU 40a calculates the relative speed of the at least one target of the device 1 using the distance, that is, the observation between the at least one target and the device 1 with the normal reliability level. In contrast, in step S220, the CPU 40a determines that the distance between a corresponding at least one target and the device 1 measured as an observation in step S190 has a lower confidence level than the normal confidence level. Then, at step S220, the CPU 40a calculates the relative speed of the at least one target to the device 1 using the distance, that is, the observation between the at least one target and the device 1 with the low reliability level.

For example, in each of steps S210 and S220, the CPU 40a calculates the relative speed of the at least one target to the device 1 using the distance between the at least one target and the device 1 using a time series filter such as the Kalman filter.

wobei χ_k\k-1 eine a-priori-Zustandsschätzung relativer Geschwindigkeit des mindestens einen Ziels beim k-ten Zyklus gemäß Beobachtungen ist, die vor dem gegenwärtigen Messzyklus gemessen wurden, z̃_k die Innovation oder das Mess-Residuum ist, und K die Kalmanverstärkung repräsentiert.Specifically, assuming that the current measurement cycle is a kth cycle, in each of steps S210 and S220, the CPU 40a calculates an a posteriori estimate χ _k\k relative velocity of the at least one target at the current measurement cycle according to the following Kalman -Filter equation: $$x_{k|k}=x_{k|k-1}+K{\widetilde{\mathrm{e.g}}}_k,$$

where χ _k\k-1 is an a priori relative velocity state estimate of the at least one target at the k th cycle according to observations measured prior to the current measurement cycle, z̃ _k is the innovation or measurement residual, and K is the represents Kalman gain.

That is, in step S210, the CPU 40a calculates an a posteriori estimate χ _k\k relative velocity of the at least one target at the current measurement cycle according to the Kalman fil ter equation such that a value of the Kalman gain K is increased in comparison with a value of the Kalman gain K of the Kalman filter equation used in step S220. On the other hand, in step S220, the CPU 40a calculates an a posteriori estimate χ _k\k relative velocity of the at least one target at the current measurement cycle according to the Kalman filter equation such that a value of the Kalman gain K compared to a value of the Kalman gain K of the Kalman filter equation used in step S210 is reduced.

The operation in step S210 or S220 explained above reduces the reliability level of the observation at the current measurement cycle when the mode transition of the device 1 is a specific mode transition, compared to the reliability level of the observation at the current measurement cycle when the mode transition is the Device 1 is not a specific mode.

Subsequent to step S210 or S220, at step S230, the CPU 40a outputs target information including the distance between the at least one target and the device 1 and the relative speed of the at least one target to the device 1 to the at least one ECU for different control of the motor vehicle MV. The target information is used by different application programs of the at least one ECU for different control of the motor vehicle MV.

Furthermore, in step S230, the CPU 40a updates the current mode of the device 1 stored in step S190 to a previous mode of the device for the next measurement cycle, which terminates the target acquisition task.

7 12 is a view schematically illustrating how a first distance measurement D1 and/or a second distance measurement D2 is measured and how distance data D is calculated for each measurement cycle Tcycl. In 7 NULL represents that a corresponding first or second distance measurement D1 or D2 is zero.

As in 7 1, even if a first or second distance measurement D1 or D2 by the first or second measurement circuit 321 or 322 is zero in a measurement cycle, such as the upper measurement cycle in FIG 7 and the third measurement cycle from the top of the same diagram obtains corresponding distance data by distance measurement circuit 32 without using interpolation or other similar data correction.

Furthermore, when the mode information of the device 1 is switched from the first mode to the third mode directly and not via the second mode or from the third mode directly to the first mode and not via the second mode in one measurement cycle (cf. a first section P1 or a second section P2, which is surrounded by a dash-dotted block in 7 is surrounded), the relative speed of a corresponding target to the device 1 is calculated while reducing the reliability level of a corresponding observation (the distance between the corresponding target and the device 1).

As described above, the target information measurement device 1 according to this embodiment is configured such that the first measurement circuit 321 and the second measurement circuit 322 operate in parallel for each receiving channel CHi to obtain a first distance measurement D1 and a second distance measurement D2. The target information measurement device 1 is also configured to generate, as the distance data D for each receiving channel CHi, the first distance measurement D1 when the level of a corresponding received signal Ri is included in the range C equal to or greater than the second threshold level. The target information measuring device 1 is further configured to generate the second distance measurement D2 as the distance data D for each reception channel CHi when the level of a corresponding received signal Ri is included in the range A equal to or smaller than the first threshold level. In addition, the target measuring device 1 is configured to generate a weighted average of the first and second distance measurements D1 and D2 as distance data D for each reception channel CHi.

This configuration of the device 1 enables distance data to be calculated with the highest accuracy using the second distance measurement D2 every measurement cycle Tcycl even if the first measurement circuit 321 cannot acquire the first distance measurement D1 due to, for example, the intensity of a corresponding echo being low or the accuracy level of the first distance measurement D1 is low. Thereby, the distance of a corresponding target from the device 1 is obtained at each measurement cycle Tcycl based on the measured distance data D, and thereby the relative speed of the corresponding target to the device 1 is obtained with the highest possible accuracy.

In addition, the configuration of the target information measuring device 1 enables distance data D using a weighted average intersection of the first and second distance measurements D1 and D2 each time the first and second measurement circuits 321 and 322 used for the calculation of distance data D are changed. This reduces the frequency of large variations in the distance data D, that is, the occurrence of distance jumps, that is, abrupt changes in the distance.

These technical effects of the target information measuring device 1 result in improvement of various vehicle control performed based on the target information measured by the device 1 . The target information includes the distance of at least one target from device 1 and the relative speed of the at least one target to device 1.

In addition, the target information measuring device 1 is configured to adjust the reliability level of an observation, that is, distance data used for calculating the relative speed of at least one target to the device 1, according to how the mode information of the device 1 is switched. This configuration avoids an unnaturally wide variation of a calculated relative velocity, even if there is a large grid variation in the level of one or more received signals, so that a corresponding observation is suddenly switched from the first distance measurement D1 to the second distance measurement D2 or vice versa. This leads to an improvement in various vehicle controls performed according to the target information measured by the device 1 . The target information includes the distance of at least one target from device 1 and the relative speed of the at least one target to device 1.

Furthermore, the first measurement circuit 321 performs the first distance measurement task using the N pulses of the signal ST transmitted at each measurement cycle Tcycl to generate a first distance measurement D1 corresponding to a received signal Ri. The second measurement circuit 322 also performs the second distance measurement task using all of the N pulses of the signal ST to generate a second distance measurement D2 corresponding to the received signals Ri. Thus it is possible to obtain first and second distance measurements D1 and D2 based on a same received signal Ri within each measurement cycle Tcycl. For this reason, it is possible to obtain target information with a high level of accuracy every measurement cycle Tcycl even if the relative spatial relationship between at least one target and the device 1 varies rapidly.

Second embodiment

A target information measuring device 1a according to a second embodiment of the present invention will be explained below. Usually, when echoes reflected from different targets are returned to a radar device, the echoes differ in intensity depending on the distances of the different targets and the types of the different targets from each other (cf 8th ). In particular, since radar devices for automobiles must detect different targets over a wide range of distances, they can receive returns with differences in intensity, at least one of which can go over a dynamic range of 10 ⁵ . In ordinary radar devices, such echoes are converted into received signals and the received signals are amplified by appropriate amplifiers. However, since no amplifier has such a wide input dynamic range that can receive the received signals when an echo has an intensity level equal to or greater than a certain intensity level, a corresponding received signal amplified by the amplifier can have a saturated have a waveform (cf 9 ).

For this reason, when a received signal amplified by the amplifier is saturated, the radar device may not detect the intensity of a corresponding echo. This can cause the radar device to use which one of a first distance measurement D1 and a second distance measurement D2 as distance information.

The target information measurement device 1a aims to address such a problem.

The structure and/or functions of the target information measuring device 1a according to the second embodiment differ from the target information measuring device 1 according to the first embodiment in the following points. Accordingly, the different points are mainly explained below.

According to 10 the target information measuring device 1a consists of a transmission module 10a, a receiving module 20a, a distance measuring module 30a and a signal processing module 40a according to the same structure as that of the target information measuring device 1.

Specific structures of the modules 10a, 20a, 30a and 40a of the device 1a differ from the modules 10, 20, 30 and 40 of the device 1 according to the first embodiment. Thus, the different structural points of the modules 10a, 20a, 30a and 40a are mainly explained below.

According to 10 For example, the transmission module 10a consists of a light-emitting element 111 such as a light-emitting diode, a first driver 112, a collimating lens 113, a scanner 114, a second driver 115, and a rotary position sensor 116.

The light emitting element is operable to emit laser pulses. The first driver 112 is operable to drive the light emitting element 111 to emit laser pulses according to a transmission timing signal ST input thereto from the signal processing module 40A. The collimating lens 113 operates to adjust the width of a beam of emitted laser pulses.

The scanner 114 is equipped with a polygon mirror 114a having a hexagonal cylindrical shape with six reflecting sides (mirrors). The polygon mirror 114a is provided to rotate around a rotation axis. The polygon mirror 114a is arranged such that: the axis of rotation is parallel to the height direction of the motor vehicle MV; and the path of a beam of laser pulses output by the collimating lens 113 hits at least one reflecting face of the polygon mirror 114a. The scanner 114 is also equipped with a motor (not shown) which rotates the polygon mirror 114a around the rotation axis so that the laser pulses output by the collimating lens 113 are reflected by the reflective sides of the polygon mirror 114a. As a result, the direction of each laser pulse can be changed so that the laser pulses scan a target region in front of the motor vehicle MV.

The second driver 115 operates to drive the motor according to drive signals DR provided from the signal processing module 40a to thereby rotate the polygon mirror 114a explained above. The rotational position sensor 16 is operative to measure a rotational position of the polygon mirror 114a and to output a rotational position signal PO indicative of the measured rotational position of the polygon mirror 114a to the signal processing module 40a.

The receiving module 20a consists of a condenser lens 121, a receiving element 122 and an amplifier 123. The receiving element 122 is a well-known image sensor composed of, for example, a photodetector such as a CMOS element or a CCD.

For example, the condenser lens 121 has a light-receiving surface with a size corresponding to the size of the target region, and operates to receive echoes incident on the light-receiving surface from the target region and condenses the echoes of the received lens 122. The receiving element 122 is provided to receive the echoes which are concentrated by the condenser lens 121 and generate received signals each having a voltage level dependent on the intensity of a corresponding echo. The amplifier is provided to amplify received signals output from the receiving element 122 and provide amplified received signals to the distance measurement module 30a as received signals R.

It should be noted that the amplifier 123 has a gain determined to amplify an echo returned from a section having a long section to the motor vehicle MV such that the level of a corresponding received signal R can be processed as an output of the amplifier 123 by the distance measurement module 30a. This causes the level of a received signal R as an output of the amplifier 123, which corresponds to an echo received from a portion at a relatively short distance from the motor vehicle MV, to be saturated.

In this embodiment, the signal processing module 40A is provided to perform all the functions of the control circuit 31 according to the first embodiment.

In particular, as above regarding 2 , the signal processing module 40A is designed to generate a periodic signal consisting of regular pulses with a measurement cycle Tcycl of, for example, 33 milliseconds. The signal processing module 40A generates a set of a predetermined number of N pulses of the transmission timing signal ST every time a pulse of the periodic signal is generated in the same manner as the control circuit 31 according to the first embodiment. As in the first embodiment, the limitation of the distance detectable by the device 1 is set to 50 m, the maximum measurement period is set to 0.33 µs, and the constant interval Tw between each pair of adjacent transmission timing signals ST is set to 18 µs .

The distance measurement module 30A consists of a first measurement circuit (single-scan distance measurement circuit) 131 and a second measurement circuit (integral distance measurement circuit) 132, which are substantially identical in structure and function to the first measurement circuit 321 and the second measurement circuit 322, respectively.

For example, the first measuring circuit 131 consists of a comparator 131a, a timer 131b and a calculator 131c, which are identical to the associated comparator 321a, timer 321b and calculator 321c.

That is, the first measurement circuit 131 is provided to generate a first timing when the level of a received signal R exceeds the threshold level, i.e., passes the threshold level for the first time, and to generate a second timing when the level of the received signal R falls below the threshold level, that is, the next time the threshold level is passed. The first measurement circuit 131 is provided to measure a first elapsed time Tf1 between the transmission timing of a laser pulse corresponding to the received signal R and the first timing, and a second elapsed time Tb1 between the transmission timing of the laser pulse corresponding to the received signal R and the second timing measure up. The first measurement circuit 131 is also provided to calculate an average of the first and second elapsed times Tf1 and Tb1 as an elapsed time Tr1 between the transmission timing and the reception timing. The elapsed time Tr1 is given by the following equation: Tr1=(Tf1+Tb1)/2. Thereafter, the first measuring circuit 321 is arranged to define the elapsed time Tr1 as a parameter P having a correlation with the intensity of a corresponding echo, and to convert the elapsed time Tr1 into a distance value to a target according to the received signal R and an the signal processing module 40A to output the distance value as a first distance measurement D1. The parameter P is also referred to as an intensity parameter P .

As a specific structural example or a single structural example of the first measurement circuit 131 according to this embodiment, a first timer 131b1 and a second timer 131b2 are provided in the first measurement circuit 131 as the timer 131b. Each of the first and second timers 131b1 and 131b2 starts counting up a digital count value from its initial value 0 every period of an operation clock provided from the signal processing module 40a, for example. That is, the update period of the LSB of the digital count of both the first timer 131b1 and the second timer 131b2 is identical to the period of the operation clock. The update period of the LSB of the digital count of each of the first to fourth timers is set to 0.125 ns.

The first timer 131b stops counting up the digital count value when the level of a corresponding received signal R lower than the threshold level exceeds the threshold level. The second timer 131b2 stops counting up the digital count value when the level of a corresponding received signal higher than the threshold level falls below the threshold level.

For example, when the maximum level of a corresponding received signal Ri exceeds the threshold level, the first measurement circuit 131 calculates a first distance measurement D1 and a value of the intensity parameter P using the timed digital count of the first timer 131b1 and the timed digital count of the second timer 131b2. The timed digital count of the first timer 131b1 represents the first elapsed time Tf1, and the timed digital count of the second timer 131b2 represents the second elapsed time Tb1.

On the other hand, when the maximum level of a corresponding received signal R is equal to or less than the threshold level, the measurement circuit 131 outputs a first distance measurement D1 and a value of the intensity parameter P, each of which is zero.

• Der erste Fall ist, dass der Pegel des empfangenen Signals R nicht gesättigt ist, da die Intensität eines entsprechenden Echos relativ niedrig ist (vergleiche den durchgezogenen Signalverlauf W1 in 11).
• Der zweite Fall ist, dass der Pegel des empfangenen Signals R gesättigt ist, da die Intensität eines entsprechenden Echos relativer Mittelpegel bzw. Zwischenpegel ist (vergleiche den strichpunktierten Signalverlauf W2 in 11).

11 schematically illustrates the signal curves of a received signal R for the following three (first to third) cases:

• The first case is that the level of the received signal R is not saturated because the intensity of a corresponding echo is relatively low (compare the solid waveform W1 in 11 ).
• The second case is that the level of the received signal R is saturated, since the intensity of a corresponding echo is relative intermediate level (compare the dot-dash waveform W2 in 11 ).

The third case is that the level of the received signal R is saturated, since the intensity of a corresponding echo is relatively high, so the saturation of the level of the received signal R for the third case is greater than that of the level of the received signal for the second case (compare the dashed signal curve W3 in 11 ).

As indicated by waveforms W1, W2, and W3 in 11 1, the length of time of a received signal represented as an elapsed time Tr1 increases as the intensity of a corresponding echo increases. Thus, the time length Tr1 of a received signal correlates with the intensity of a corresponding echo. For this reason, the time length Tr1 of a received signal R is used as the intensity parameter P.

With the same paragraph as the second measurement circuit 322, the second measurement circuit 132 is provided to sample N received signals R, i.e. R1, R2, ..., RN corresponding to the respective N pulses of the transmission timing signal ST at predetermined sampling intervals Tsmpl during the lapse of the maximum measurement period based on the transmission timing of a corresponding pulse of the transmission timing signal ST.

Then, the second measuring circuit 132 is provided to extract first through M-th sets of sampled levels from all of the sampled levels and to integrate the sampled levels of each of the first through M-th sets with each other to obtain first through M-th integrated sampled levels for the corresponding first to M-th sentences (compare 3B , in which Ri1 to RiN corresponds to R1 to RN). The second measurement circuit 132 generates a first timing and a second timing of a discrete signal consisting of the first through Mth integrated sampled levels for the corresponding first through Mth sets using the threshold level with the same approach as that explained above first measuring circuit 131. Then, the second measuring circuit 132 is provided to calculate a first elapsed time Tf2 between the reference transmission timing and the first timing, and measures a second elapsed time Tb2 between the reference transmission timing and the second timing according to equations (1) and (2 ).

Then, the second measuring circuit 132 is provided to calculate an elapsed time Tr2 between the reference transmission timing and the received timing as the middle of the first and second timings using the first and second elapsed times Tf2 and Tb2 with the same approach as the first measuring circuit 131. Then, the second measurement circuit 132 is provided to define the elapsed time Tr2 and to convert the elapsed time Tr2 into a value of a distance to a target according to the received signal R and to the signal processing module 40A to output the distance value as a second distance measurement D2 .

According to 10 For example, the signal processing module 40A is provided as an ordinary microcomputer circuit composed of, for example, a CPU 400, a storage medium 401 including volatile and non-volatile memory, and an IO (input/output, input and output) interface, etc.

The normal microcomputer circuit is defined in this embodiment to include at least a CPU and a main memory such as the storage medium.

The CPU 400 of the signal processing module 40A is designed to perform a sampling task. The scanning task controls, based on the rotational position signal PO output from the rotational position sensor 16, the driving signals DR provided to the second driver 115 such that a predetermined angular rotation of the polygon mirror 114a is synchronized with every period of N pulses of the transmission signal. Controlling the drive signal DR causes, for example, laser pulses output from the light emitting element 111 corresponding to N pulses of the transmission timing signal ST to sequentially scan the target region from one end of the target region to the other end of the target region in the width direction of the motor vehicle MV.

The CPU 400 is also configured to perform, according to a corresponding program PR2 stored in the storage medium 401, at least a distance information selection task, that is, a target information determination task using the intensity parameter P during execution of the scanning task. The distance information selection task is for selecting any one of a first distance measurement D1 and a second distance measurement D2 as distance information between a corresponding target and the motor vehicle MV.

12 12 schematically illustrates specific operations, ie steps of the CPU 400 in the distance information selection task will be explained in detail below. It should be noted that the CPU 400 activates the program PR2 to activate the distance information selection task whenever measured data, that is, a first distance measurement D1, a second distance measurement D2, and the intensity parameter P obtained by the distance measurement module 30a of the CPU 400 are provided. In other words, the CPU 400 activates the program PR2 to start the distance information selection task for each measurement cycle Tcycl.

When the program PR2 is activated, the CPU 400 acquires measured data, that is, a first distance measurement D1, a second distance measurement D2, and the intensity parameter P, provided by the distance measurement module 30A at step S310.

Next, at step S320, the CPU 400 determines whether the intensity parameter P representing the time length Tr1 of a corresponding received signal R exceeding the threshold level is greater than a predetermined threshold Pth. It should be noted that the threshold level Pth is determined such that the accuracy level of a first distance measurement D1 is greater than that of a second distance measurement D2 when the intensity parameter P is greater than the threshold Pth. This determination of the threshold value Pth can be easily performed according to, for example, an example of the relationships between the received signal levels and the accuracy levels of the first and second distance measurements made by the respective first and second measurement circuits 131 and 132 (cf 4 ) be performed.

When determining that the intensity parameter P is greater than the threshold value Pth (YES in step S320), the CPU 400 selects the first distance measurement D1 obtained by the first measurement circuit 131 as distance information between a corresponding at least one target and the system 1A in step S330. On the other hand, when it is determined that the intensity parameter P is equal to or smaller than the threshold value Pth (NO in step S320), the CPU 400 selects the second distance measurement D2 obtained by the second measurement circuit 132 as distance information between a corresponding at least one target and the system 1A in step S340.

Thereafter, the CPU 400 can perform the following operations S350, S360 and S370 similarly to the operation in steps S210, S220 and S230 shown in FIG 4 are illustrated.

Specifically, subsequent to step S330, the CPU 400 calculates the relative speed of a corresponding at least one target to the device 1A using the distance information selected in step S330 in step 350. On the other hand, subsequent to step S340, the CPU 400 calculates the relative speed of a corresponding at least one target to the device 1A using the distance information selected in step S330 in step S360.

Following step S350 or step S360, the CPU 400 outputs to the at least one ECU for different control of the motor vehicle MV target information including the distance between the at least one target and the device 1A and the relative speed of the at least one target to the device 1A in step S370 . The target information is used by different application programs of the at least one ECU for different control of the motor vehicle MV. Thereafter, the CPU 400 terminates the distance information selection task.

As described above, the target information measurement device 1A according to this embodiment is configured such that the first measurement section 131 and the second measurement section 132 operate in parallel to obtain a first distance measurement D1 and a second distance measurement D2. The target information measuring device 1A is also configured to determine whether to use the first distance measurement D1 or the second distance measurement D2 as the distance information by using the intensity parameter P. The intensity parameter P has a correlation with the intensity of a corresponding echo and represents the length of time Tr1 of a corresponding received signal R exceeding the threshold level.

This configuration of the device 1A makes it possible to correctly obtain the intensity of an echo even when the level of a corresponding received signal R amplified by the amplifier 123 is saturated, thereby obtaining either a first distance measurement D1 and a second distance measurement D2 according to current environments around the motor vehicle MV is properly selected.

The target information measurement device 1A according to this embodiment is configured to avoid a first distance measurement D1 being selected even when receiving noise of a high level so that a received signal suddenly increases as a signal received from the target. This is because the time length of such noise exceeding the threshold level is clearly smaller than the threshold Pth. Thus, it is possible to avoid selecting a first distance measurement D1 even when there are current circumstances around the motor vehicle.

Note that the target information measurement device 1A according to this embodiment is configured to use the time length Tr1 of a corresponding received signal R exceeding the threshold level measured by the first circuit 131 as the intensity parameter P, but not limited thereto. In particular, the target information measuring device 1A may be configured to use the time length Tr2 of a corresponding received signal R exceeding the threshold level measured by the second measurement circuit 132 as the intensity parameter. In this modification, a threshold value Pth1 is determined such that the accuracy level of a second distance measurement D2 is greater than that of a first distance measurement D1 when the intensity parameter P is smaller than the threshold level Pth1. That is, in this modification, when it is determined that the intensity parameter P is smaller than the threshold value Pth1 (YES in step S320A), the CPU 400 selects the second distance measurement D2 obtained by the second measurement circuit 132 as the distance information in step S320A S340 off. Otherwise, when determining that the intensity parameter P is equal to or greater than the threshold value Pth1 (NO in step S320), the CPU 400 selects the first distance measurement D1 obtained by the first measurement circuit 131 as distance information in step S330.

Third embodiment

A target information measuring device 1B according to a third embodiment of the present invention will be explained below.

The structure and/or functions of the target information measuring device 1B according to the third embodiment differ from the target information measuring device 1A according to the second embodiment in the following points. So mainly the different points are explained below.

According to 13 , which illustrates a single structural example of the first measurement circuit 131 according to the third embodiment, first to third timers 131b1, 131b2, and 131b3 are provided in the first measurement circuit 131 as the timer 131b. The first timer 131b1 and the second timer 131b2 according to the third embodiment are identical in function to the first timer 131b1 and the second timer 131b2 according to the second embodiment, respectively.

The third timer 131b3 starts incrementing a digital count value from its input value 0 at each rising edge of each pulse of the transmission timing signal ST. The third timer 131b stops incrementing the digital count value when the level of a corresponding received signal R lower than a stop threshold level exceeds the stop threshold level. The stop threshold level is determined to be lower than the threshold level and higher than an average noise level of the received signals. The threshold level and the stop threshold levels are denoted by reference characters TH1 and TH2, respectively.

As described above, the first measurement circuit 131 calculates a first distance measurement D1 and a second distance measurement D2 based on the digital count (first elapsed time Tf1) of the first timer 131b1 and the digital count (second elapsed time Tb1) of the second timer 131b2.

wobei Ts den gestoppten digitalen Zählwert des dritten Zeitgebers 131b3 entsprechend einer dritten abgelaufenen Zeit repräsentiert.In addition, the first measurement circuit 131 calculates the gradient K of a rising edge of a corresponding received signal R using the following equation: $$\text{K}=\left(\text{tf}1-\text{ts}\right)/\left(\text{th}1-\text{th}2\right),$$

where Ts represents the stopped digital count of the third timer 131b3 corresponding to a third elapsed time.

The first measurement section 131 calculates the distance value corresponding to the elapsed time Tr1 based on the first elapsed time Tf1 and the second elapsed time Tb1. Then, the first measurement circuit 131 outputs to the signal processing module 40A the distance value as a first distance measurement D1 and the gradient K of a rising edge of a corresponding received signal R as an intensity parameter PA. The gradient K (intensity parameter PA) has a correlation with the intensity of a corresponding echo.

Note that when the maximum level of a corresponding received signal R does not exceed the threshold level TH1, the first timer 131b1 times out, that is, the first timer 131b1 times out when no information is input thereto , the first measurement circuit 131 cannot calculate the first elapsed time Tf1. At this time, the first measurement circuit 131 fixes the gradient K to zero.

• Der erste Fall ist, dass der Pegel des empfangenen Signals R nicht gesättigt ist, da die Intensität eines entsprechenden Echos relativ niedrig ist (vergleiche den durchgezogenen Signalverlauf W11 in 14).
• Der zweite Fall ist, dass der Pegel des empfangenen Signals R gesättigt ist, da die Intensität eines entsprechenden Echos ein relativer Zwischen- bzw. Mittelpegel ist (vergleiche den strichpunktierten Signalverlauf W12 in 14).
• Der dritte Fall ist, dass der Pegel des empfangenen Signals R gesättigt ist, da die Intensität eines entsprechenden Echos relativ hoch ist, so dass die Sättigung des Pegels des empfangenen Signals R für den dritten Fall größer als die des Pegels des empfangenen Signals R für den zweiten Fall ist (vergleiche den gestrichelten Signalverlauf W13 in 14).

14 shows schematically the signal curves of a received signal R for the following three (first to third) cases:

• The first case is that the level of the received signal R is not saturated because the intensity of a corresponding echo is relatively low (compare the solid waveform W11 in 14 ).
• The second case is that the level of the received signal R is saturated, since the intensity of a corresponding echo has a relative intensification mean level (compare the dot-dash signal curve W12 in 14 ).
• The third case is that the level of the received signal R is saturated, since the intensity of a corresponding echo is relatively high, so the saturation of the level of the received signal R for the third case is greater than that of the level of the received signal R for the second case (compare the broken signal curve W13 in 14 ).

As indicated by waveforms W11, W12, and W13 in 14 is illustrated, the gradient K of a rising edge of a received signal R increases with the increasing intensity of a corresponding echo. Thus, the gradient K of a rising edge of a received signal R correlates with the intensity of a corresponding echo. For this reason, the gradient K of a rising edge of a received signal R can be used as the intensity parameter PA.

That is, the CPU 400 of the signal processing module 40A of the target information measurement device 1B according to this embodiment determines whether the intensity parameter P representing the gradient K of a rising edge of a corresponding received signal R is greater than a predetermined threshold value Pth in step S320. It should be noted that the threshold Pth is determined such that the accuracy level of a first distance measurement D1 is higher than that of a second distance measurement D2 when the intensity parameter P is greater than the threshold Pth.

Since other functions of the target information measuring device 1B are substantially identical to those of the target information measuring device 1A, the description thereof is omitted.

As described above, the target information measuring device 1B according to this embodiment is configured to determine whether to select a first distance measurement D1 or a second distance measurement as distance information by using, as the intensity parameter P, the gradient K of a rising edge of a corresponding received signal R is used. The gradient K has a correlation with the intensity of a corresponding echo.

This configuration of the device 1B makes it possible to properly obtain the intensity of an echo even when the level of a corresponding received signal R amplified by the amplifier 123 is saturated, making a first distance measurement D1 or a second distance measurement D2 according to current environments around the motor vehicle is properly selected.

Note that the target information measurement device 1B according to this embodiment is configured to use the gradient K of a rising edge of a corresponding received signal R measured by the first measurement section 131 as the intensity parameter P, but is not limited thereto . In particular, the target information measurement device 1B may be configured to use a rise time of a corresponding received signal R expressed as the subtraction of the first elapsed time Tf1 from the third elapsed time Ts and measured by the first measurement circuit 131 as the intensity parameter P.

The target information measurement device 1B may be configured to use the gradient K of a rising edge of a corresponding received signal R measured by the second measurement section 132 as the intensity parameter P. The target information measurement device 1B may be configured to use a rise time of a corresponding received signal R expressed as the subtraction of the second elapsed time Tf2 from the third elapsed time T and measured by the second measurement section 132 as the intensity parameter P.

In addition, the target information measuring device 1B according to this embodiment is configured to measure the gradient K of a rising edge of a corresponding received signal R using a time (Tf1 - Ts) from when the level of the received signal R exceeds the threshold level until when it exceeds the threshold level , to calculate. However, the target information measurement device 1B is not limited to this configuration.

Specifically, the target information measuring device 1B may be configured to measure the gradient K of a rising edge of a corresponding received signal R using the time from when the level of the received signal R exceeds the threshold level to when it reaches a level at which the level of the received signal R is saturated.

The first to third embodiments of the present invention have been explained in detail above, but the present invention is not limited to these embodiments and can be modified as follows.

The first embodiment, the second embodiment, and the third embodiment can be freely combined with each other.

• Steuern eines Warnbuzzers und eines Monitors eines entsprechenden Kraftfahrzeugs zum Bereitstellen hörbarer und/oder sichtbarer Warnung für einen Fahrer des entsprechenden Kraftfahrzeugs;
• Steuern von Bremsen des entsprechenden Kraftfahrzeugs um eine Vollbremsung auszuüben, und/oder
• Anziehen der Sitzgurte des entsprechenden Kraftfahrzeugs.

It should be noted that a so-called pre-crash safety system is provided in order to based on both the distance from at least one target to a corresponding motor vehicle and the relative speed of the at least one target to the corresponding motor vehicle to carry out the following pre-crash safety task:

• controlling a warning buzzer and monitor of a corresponding motor vehicle to provide audible and/or visual warning to a driver of the corresponding motor vehicle;
• Controlling the brakes of the corresponding motor vehicle in order to apply emergency braking, and/or
• Tightening the seat belts of the relevant motor vehicle.

Thus, as described above, a sensor for a pre-crash safety system installed in a motor vehicle needs to measure the speed of at least one target, such as its relative speed to the corresponding motor vehicle. For this reason it is desirable that such a sensor reliably measures the distance from at least one target to a corresponding motor vehicle for each constant cycle. It is also desirable for such a sensor to measure the distance of the at least one target from a corresponding motor vehicle with the greatest possible accuracy since the measured distance is used for safety control of the corresponding motor vehicle. Accordingly, each of the target information measuring devices 1, 1A and 1B can be preferably applied to such sensors for pre-crash systems.

The target information measurement apparatus 1 according to the first embodiment uses a fixed value of 0.3 for α when obtaining distance data D of a selected channel Chi representing the weighted average of the measurements D1 and D2, but may be configured to use a value as α which is variable depending on the intensity of a corresponding received signal Ri.

The target information measuring device 1 according to the first embodiment uses the first threshold level and the second threshold level as a threshold level used for the first measuring circuit 321, but may use three different threshold levels or a single threshold level as the threshold level used for the first measuring circuit 321 .

• als den Abstand zwischen dem gleichen Ziel und der Vorrichtung 1 eines der Stücke von Abstandsdaten D entsprechend dem höchsten Modus bezüglich Genauigkeit aller Modi der Stücke von Abstandsdaten D zu bestimmen; und
• als Modusinformation der Vorrichtung 1 den höchsten Modus zu bestimmen.

When a cluster including pieces of distance data D corresponding to a plurality of receiving channels Ri is detected as a same target, in step S190 the target information measuring device 1 is configured to:

• to determine, as the distance between the same target and the device 1, one of the pieces of distance data D corresponding to the highest mode in accuracy of all the modes of the pieces of distance data D; and
• to determine the highest mode as the mode information of the device 1 .

However, the target information measurement device 1 is not limited to this configuration.

• als die Abstandsdaten zwischen dem gleichen Ziel und der Vorrichtung 1 ein Stück von Abstandsdaten D entsprechend einem empfangenen Kanal Chi bestimmen, die in der Mitte der mehreren empfangenen Signale Ri platziert sind; und
• als Modusinformation der Vorrichtung 1 den Modus entsprechend dem einen Stück von Abstandsdaten D zu bestimmen.

Specifically, when a cluster including pieces of distance data D corresponding to a plurality of reception channels Ri is detected as a same target, the target information measuring device 1 may be configured in step S190 to:

• as the distance data between the same target and the device 1, determine a piece of distance data D corresponding to a received channel Chi placed at the center of the plurality of received signals Ri; and
• to determine the mode corresponding to the one piece of distance data D as mode information of the device 1 .

The target information measuring device 1 is configured to use a time-series filter in calculating the relative speed of at least one target and the device 1, however, it may be configured to use a derivative of the distance between a corresponding at least one target and the device 1, the is measured in step S190.

The target information measuring device 1 according to the first embodiment is provided to radiate laser pulses as signal pulses to the entirety of the target region and receive echoes reflected from plural portions of the target region corresponding to plural reception channels, thereby scanning the target region. For example, an example of the laser irradiation and the echo receiving method is disclosed in Japanese Patent Application Publication No JP H06 - 305 383 A1 disclosed. However, the target information measuring device 1 according to the first embodiment may be provided to scan the target region in the same manner as the target information measuring device 1A or 1B according to the second or third embodiment.

Similarly, each of the target information measuring devices 1A and 1B according to the second and Third Embodiment may be designed to scan the target region in the same manner as the target information measuring device 1 according to the first embodiment.

In each of the first to third embodiments, a corresponding information measurement device may be configured to electronically scan the target region using laser pulses.

In each of the second and third embodiments, a corresponding target information measurement device is configured such that the distance measurement module 30A acquires the intensity parameter P, but the present invention is not limited thereto. In particular, a corresponding target information measuring device can be configured such that the distance measuring module 30A sends to the signal processing module 40A data necessary to obtain the intensity parameter P, such as a first elapsed time Tf1 and a second elapsed time Tb1, the signal processing module 40A denoting the Intensity parameter P obtained using the data.

In each of the second and third embodiments, the threshold Pth is determined such that the accuracy level of a first distance measurement D1 is higher than that of a second distance measurement D2 when the intensity parameter P is greater than the threshold Pth, but the present invention is not limited thereto . In particular, the threshold Pth may be determined such that the accuracy level of a first distance measurement D1 is equal to or greater than an accuracy level required by each of the application programs using the first distance measurement D1.

Claims (10)

A target information measurement device, comprising: a transceiver module (10, 10A, 20, 20A) that transmits a plurality of signal pulses and receives a plurality of echoes based on the plurality of signal pulses every predetermined measurement cycle to obtain a plurality of received signals, each having an intensity of a corresponding one of the plurality of echoes represents; a first measurement module (321, 131) that: measures, for each measurement cycle, a first elapsed time between a transmission time of a signal pulse in the plurality of signal pulses and a first time, the first time being a time when a level of a received signal corresponding to the one signal pulse passes a predetermined threshold level, the received signal being defined as a signal received from the target; and based on the first elapsed time, obtains a first measurement representing distance information to a target from the target information measuring device, the target generating an echo based on the one signal pulse corresponding to the signal received from the target; a second measurement module (322, 132) that: for each measurement cycle, samples each of the plurality of received signals at predetermined sampling intervals to obtain sampled levels for each of the plurality of received signals; extracting a plurality of sets of sampled levels, the sampled levels of each of the plurality of sets corresponding to the plurality of received signals, respectively, and the sampling timings of the sampled levels of each of the plurality of sets have an identical elapsed time with respect to the transmission timing of a corresponding one of the plurality of signal pulses; integrates the sampled levels of each of the plurality of sets together to obtain a plurality of integrated sampled levels to obtain a second measurement representing the distance information to the target from the target information measuring device based on the plurality of integrated sampled levels; a determiner (40, 40A) determining how to use the first measurement and/or the second measurement to finally determine a distance of the target according to a parameter, the parameter having a correlation with an intensity of at least one of the plurality of echoes ; and a velocity calculator (40, 40A, S190 to S220) configured to calculate, for each measurement cycle, a velocity of the target according to the final determined distance of the target, wherein the first measurement module is configured to: a first threshold level that is higher than a predetermined noise level, and having as the threshold level a second threshold level that is higher than the first threshold level; for each measurement cycle, measure the first elapsed time between the transmission instant of the one signal pulse and the first instant using the second threshold level as the threshold level when the level of the signal received from the target is higher than the second threshold level; and for each measurement cycle, measuring the first elapsed time between the transmission instant of the one signal pulse and the first instant using the first threshold level as the threshold level when the level of the signal received from the target is equal to or less than the second threshold level, and wherein the determining means is configured to use the first measurement when the level of the signal received from the target, which is the parameter is higher than the second threshold level to definitively determine the distance of the target to use the second measurement when the level of the signal received from the target representing the parameter is lower than the first threshold level to definitively determine the distance of the target, and using an average of the first measurement and the second measurement when the level of the signal received from the target is equal to or greater than the first threshold level and equal to or less than the second threshold level to definitively determine the distance to the target determine. Target information measuring device according to claim 1 , wherein the target information measuring device is in a first mode in which the finally determined distance of the target is the first measurement, the target information measuring device is in a second mode in which the finally determined distance of the target is the average of the first measurement and the second measurement, and the target information measuring device is in a third mode in which the finally determined distance of the target is the second measurement, and the speed calculator is configured to calculate the speed of the target using a time series filter such that the calculated speed has a lower reliability level than a reference reliability level when the target information measuring device is directly switched in its mode from one of the first mode and the third mode to the other thereof without going through the second mode. Target information measuring device according to claim 2 , wherein the time series filter is a Kalman filter with a gain, and the velocity calculator is configured to adjust the confidence level of the finally determined range of the target by changing the gain. Target information measuring device according to one of Claims 1 until 3 , wherein the determiner is configured to calculate a weighted average of the first measurement and the second measurement as the average of the first measurement and the second measurement. Target information measuring device according to one of Claims 1 until 4 , characterized in that the first measurement module is configured to measure the first elapsed time in increments of time units, the time unit being shorter than the sampling interval. Target information measuring device according to claim 1 , wherein the parameter increases as the intensity of the at least one of the plurality of echoes increases, wherein the at least one of the plurality of echoes is an echo corresponding to the signal received from the target, and the determiner is configured to select the first measurement to definitively determine the distance to the target using the selected first measurement if a value of the parameter is greater than a threshold, and select the second measurement to finally determine the distance to the target using the selected second measurement if the value of the parameter is equal to or greater than the limit. Target information measuring device according to claim 6 , further comprising: a parameter acquirer (40A, step S310) configured to acquire, as the parameter, a time length of the signal received from the target exceeding the threshold value. Target information measuring device according to claim 6 , further comprising: a parameter obtainr (40A, step S310) configured to obtain from the parameter a gradient of a rising edge of the signal received from the target. Target information measuring device according to one of Claims 6 until 8th , wherein the threshold level is determined such that an accuracy level of the first measurement is equal to or greater than an accuracy level of the second measurement. Target information measuring device according to one of Claims 6 until 8th wherein the finally determined distance of the target is used by an application program of a control unit, and the threshold level is determined such that an accuracy level of the first measurement is equal to or greater than an accuracy level required for the application program.

Images