TW202242445A - Ranging system - Google Patents

Abstract

A ranging system includes: a source generating a wideband incident wave that is transmitted toward a target and that is reflected by the target to form a reflected wave; a feedback detector to detect the reflected wave to generate a detected signal; an operator configured to perform low-pass filtering on the detected signal at an adjustable filtering bandwidth to generate a filtered signal, and calculate cross-correlation of a feedback signal that originates from the filtered signal and a reference signal that corresponds to the incident wave to generate a cross-correlation result; and a controller calculating a distance to the target based on an operation output that originates from the cross-correlation result.

Description

ranging system

The present invention relates to a ranging technology, in particular to a ranging system.

A lidar system is a system that measures a distance from the lidar system to the target by illuminating a target with laser light and measuring the flight time required for the laser light to return to the lidar system. When the target is within a ranging dynamic range of the lidar system, the lidar system can detect the target.

In lidar systems, a higher sampling frequency results in a better ranging resolution; and a total number of samples is limited by a given power budget, so a higher sampling frequency results in a narrower ranging dynamic range . Thus, given a power budget, the sampling frequency can be reduced to achieve a wider ranging dynamic range for which the ranging resolution is traded off, but this may result in missing targets (i.e., the targets are not detected). Furthermore, fine ranging resolution and wide ranging dynamic range cannot be achieved simultaneously without excessive power consumption.

Therefore, it is an object of the present invention to provide a distance measuring system which can improve at least one of the disadvantages of the prior art when the adjustable parameters of the distance measuring system are properly set.

Therefore, the ranging system of the present invention is suitable for measuring a distance from the ranging system to a target, and includes a source end, a feedback detector, an arithmetic unit and a controller. The source generates an incident wave of broadband. The incident wave travels toward the target and is reflected by the target to form a reflected wave. The feedback detector is used to detect the reflected wave to generate a detection signal. The arithmetic unit is electrically connected to the feedback detector to receive the detection signal therefrom, and is set to perform low-pass filtering on the detection signal under an adjustable preset filter bandwidth, so as to generate a filter signal, and calculate the source A cross-correlation between a feedback signal from the filtered signal and a reference signal corresponding to the incident wave to generate a cross-correlation result. The controller is electrically connected to the computing unit to receive an computing output from the cross-correlation result therefrom, and calculate the distance from the ranging system to the target according to the computing output.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numerals.

Referring to Fig. 1, a first embodiment of the ranging system 1 of the present invention is suitable for measuring a distance from the ranging system to a target 2, and includes a source end 11, a feedback detector 12, and a reference detector 13 , an arithmetic unit 14 and a controller 15 .

The source 11 generates an incident wave (for example, light, electromagnetic wave or sound) of broadband, which can be modulated or not modulated according to application requirements. The incident wave is transmitted to the target 2 and reflected by the target 2 to form a reflected wave.

The feedback detector 12 is used to detect the reflected wave to generate a first detection signal.

The reference detector 13 is used to detect the incident wave to generate a second detection signal.

In this embodiment, the source end 11 is a light source end (for example, a laser) that generates light as the incident wave, and each of the feedback detector 12 and the reference detector 13 is a photoelectric conversion A device (for example, a photodiode) converts a corresponding one of the reflected wave and the incident wave into an electrical signal as a corresponding one of the first detection signal and the second detection signal. However, the present invention is not limited to the above embodiments.

The computing unit 14 is electrically connected to the feedback detector 12 and the reference detector 13 to receive the first detection signal and the second detection signal from the feedback detector 12 and the reference detector 13 respectively, and is used for performing The following actions: perform low-pass filtering on the first detection signal and the second detection signal at an adjustable preset filter bandwidth, so as to generate a first filter signal and a second filter signal respectively; The first filtered signal and the second filtered signal are sampled at a preset sampling frequency so as to generate a round respectively derived from the first filtered signal and the second filtered signal and corresponding to the reflected wave and the incident wave respectively. grant signal and a reference signal; and calculate the cross-correlation between the feedback signal and the reference signal corresponding to a plurality of delay times distributed in a preset time zone to generate a cross-correlation result, wherein the preset time zone is available Optionally adjusted.

The controller 15 is electrically connected to the computing unit 14, controls the adjustable parameters in the computing unit 14 (comprising the preset filter bandwidth, the preset sampling frequency and the preset time zone), and is used to obtain from the computing unit 14 receives an operation output from the cross-correlation result, and calculates the distance from the ranging system 1 to the target 2 according to the operation output.

In this embodiment, both the first detection signal and the second detection signal are analog signals; and the arithmetic unit 14 includes a low-pass filter 141, a sampler 142 and a cross-correlator operating in the analog domain 143, and also includes an analog-to-digital converter 144.

The low-pass filter 141 has an adjustable filter bandwidth, is electrically connected to the controller 15, and is controlled by the controller 15 in such a way that the adjustable filter bandwidth is set to the preset filter bandwidth. The low-pass filter 141 is also electrically connected to the feedback detector 12 and the reference detector 13 to receive the first detection signal and the second detection signal from the feedback detector 12 and the reference detector 13 respectively, and The first detection signal and the second detection signal are low-pass filtered at the preset filter bandwidth to generate the first filter signal and the second filter signal respectively.

The sampler 142 has an adjustable sampling frequency, is electrically connected to the controller 15, and is controlled by the controller 15 in such a way that the adjustable sampling frequency is set as the preset sampling frequency. The sampler 142 is also electrically connected to the low-pass filter 141 to receive the first filtered signal and the second filtered signal from the low-pass filter 141, and the first filtered signal and the second filtered signal at the preset sampling frequency The two filtered signals are sampled to generate the feedback signal and the reference signal respectively.

The cross-correlator 143 has an adjustable time zone, is electrically connected to the controller 15, and is controlled by the controller 15 in such a way that the adjustable time zone is set as the preset time zone. The cross-correlator 143 is also electrically connected to the sampler 142 to receive the feedback signal and the reference signal from the sampler 142, and calculate the feedback signal and the reference signal corresponding to the distribution in the preset time zone. The cross-correlation with equal delay time to generate the cross-correlation result as the output of the operation. Specifically, for each delay time, the cross-correlator 143 delays the reference signal by the delay time to generate a delay signal, and calculates the dot product of the feedback signal and the delay signal. The dot products corresponding to the delay times respectively constitute the cross-correlation result.

The analog-to-digital converter 144 is electrically connected to the cross-correlator 143 to receive the operation output from the cross-correlator 143, and is also electrically connected to the controller 15, and performs analog-to-digital conversion on the operation output to generate a digital representation of the operation output to provide the controller to receive. The controller 15 calculates the distance from the ranging system 1 to the target 2 according to the operation output of the digital representation.

In a first implementation of this embodiment, the controller 15 controls the low-pass filter 141 and the sampler 142 so that the preset filter bandwidth is narrower than a signal bandwidth of the incident wave, and the preset The sampling frequency is higher than the preset filter bandwidth.

Figure 2 illustrates the simulated cross-correlation results of this embodiment under various conditions. Under all conditions, the signal bandwidth of the incident wave is 500MHz and the preset sampling frequency is 5GHz, and the preset filter bandwidth is at Infinity, 100MHz, 50MHz, 25MHz and 10MHz under various conditions. Under each condition, the delay time corresponding to the maximum dot product is the actual delay time from the reflected wave of the ranging system 1 to the incident wave. It can be reasonably determined from FIG. 2 that the lower the preset filtering bandwidth is, the wider is a pulse of the cross-correlation result including the maximum dot product. In addition, as shown in FIG. 3, when the preset sampling frequency is higher than the preset filter bandwidth, the cross-correlation result (that is, the combination of solid points and hollow points) will not lose the above pulse, thus ensuring target detection ( That is, the target 2 has been detected); and when the preset sampling frequency is lower than the preset filtering bandwidth, the cross-correlation result (that is, the solid point) may completely lose the above-mentioned pulse that should have appeared, results in a lost target (ie, the target 2 is not detected). In a first implementation of this embodiment, by making the preset filter bandwidth lower than the preset sampling frequency, even if the preset sampling frequency is lowered in order to widen a ranging dynamic range of the ranging system 1 , the target 2 will still be detected.

Referring to FIG. 1 and FIG. 4 , in a second implementation of the present embodiment, the ranging system 1 operates in the coarse mode and the fine mode in sequence. In coarse mode, the controller 15 controls the low-pass filter 141, the sampler 142 and the cross-correlator 143 so that the preset filter bandwidth, the preset sampling frequency and the preset time zone are respectively equal to one A first filtering bandwidth, a first sampling frequency and a first time zone, the first filtering bandwidth is narrower than the signal bandwidth of the incident electromagnetic signal, the first sampling frequency is higher than the first filtering bandwidth. Furthermore, the controller 15 obtains a rough delay time corresponding to the incident wave from the reflected wave of the ranging system 1 according to the calculation output. In fine mode, the controller 15 controls the low-pass filter 141, the sampler 142 and the cross-correlator 143 so that the preset filter bandwidth, the preset sampling frequency and the preset time zone are respectively equal to one The second filtering bandwidth, a second sampling frequency and a second time zone. The second filtering bandwidth is wider than the first filtering bandwidth. The second sampling frequency is higher than the second filtering bandwidth and the first sampling frequency. As shown in FIG. 4, the second time zone is narrower than the first time zone and approximately equal to the coarse delay time. Moreover, the controller 15 obtains a fine delay time corresponding to the incident wave from the reflected wave of the distance measuring system 1 according to the calculation output, and calculates the distance from the distance measuring system 1 to the target 2 according to the fine delay time distance.

In the second implementation of this embodiment, since the preset sampling frequency in the fine mode is higher than the preset sampling frequency in the coarse mode, and the preset time range in the fine mode is narrower than the The preset time range in the coarse mode, so the ranging system 1 has a wider dynamic range in the coarse mode and a better ranging resolution in the fine mode. In addition, the preset sampling frequency and the preset time region are such that a total number of samples (i.e., the dot products) included in the cross-correlation result do not exceed a predetermined power budget in both coarse and fine modes Therefore, the ranging system 1 can have an overall fine ranging resolution within a wide ranging dynamic range without excessive power consumption.

Referring to FIG. 5, a second embodiment of the ranging system 1 of the present invention is similar to the first embodiment, but differs from the first embodiment in that the cross-correlator 143 operates in the digital domain .

In the second embodiment, the analog-to-digital converter 144 is electrically connected to the sampler 142 to receive the feedback signal and the reference signal from the sampler 142, and perform analog-to-digital conversion on the feedback signal and the reference signal , to generate a digital representation of the feedback signal and a digital representation of the reference signal. The cross-correlator 143 is electrically connected to the analog-to-digital converter 144 to receive the digital representation of the feedback signal and the digital representation of the reference signal from the analog-to-digital converter 144 , and is also electrically connected to the controller 15 . The cross-correlator 143 calculates the cross-correlation between the digital representation of the feedback signal and the digital representation of the reference signal corresponding to the delay times distributed in the preset time region to generate the cross-correlation as the operation output The result is provided to the controller 15 to receive. The controller 15 calculates the distance from the ranging system 1 to the target 2 according to the operation output.

Referring to FIG. 6 , a third embodiment of the distance measuring system 1 of the present invention is similar to the first embodiment, but differs from the first embodiment in that: (a) the reference detector is omitted 13 (see Figure 1); (b) the controller 15 also generates a source signal of an analog signal; (c) the source terminal 11 is electrically connected to the controller 15 to receive the source signal from the controller 15, and according to the source signal to generate the incident wave; and (d) the low-pass filter 141 is used to receive the source signal from the controller 15, and perform low-pass filtering on the source signal under the preset filtering bandwidth to generate the first Two filtered signals.

Referring to Fig. 7, a fourth embodiment of the ranging system 1 of the present invention is similar to the second embodiment, but differs from the second embodiment in that: (a) the reference detector is omitted 13 (see Figure 5); (b) the controller 15 also generates a digital source signal; (c) the source terminal 11 is electrically connected to the controller 15 to receive the source signal from the controller 15, and according to the source signal to generate the incident wave; and (d) the operator 14 also includes another low-pass filter 145 and a decimator 146 operating in the digital domain.

In the fourth embodiment, the second filtered signal is generated by the low-pass filter 145 instead of the low-pass filter 141, and the reference signal is generated by the decimator 146 instead of is not generated by the sampler 142. Specifically, the low-pass filter 145 has an adjustable filtering bandwidth, is electrically connected to the controller 15, and is controlled by the controller 15, so that the adjustable filtering bandwidth is set to the preset filtering bandwidth. The low-pass filter 145 is used for receiving the source signal from the controller 15 and performing low-pass filtering on the source signal under the preset filtering bandwidth to generate the second filtered signal. The decimator 146 has an adjustable sampling frequency, is electrically connected to the controller 15, and is controlled by the controller 15, so that the adjustable sampling frequency is set as the preset sampling frequency. The decimator 146 is also electrically connected to the low-pass filter 145 and the cross-correlator 143, for receiving the second filtered signal from the low-pass filter 145, and down-sampling the second filtered signal to generate a The reference signal with a sampling rate equal to the preset sampling frequency is provided for the cross-correlator 143 to receive. The cross-correlator 143 calculates the cross-correlation between the feedback signal and the digital representation of the reference signal corresponding to the delay times distributed in the preset time region to generate the cross-correlation result.

Referring to FIG. 8, a fifth embodiment of the ranging system 1 of the present invention is similar to the first embodiment, but the difference from the first embodiment is that the computing unit 14 is used to perform the following actions: performing low-pass filtering on the first detection signal and the second detection signal under the preset filtering bandwidth to generate the first filtering signal and the second filtering signal as the feedback signal and the reference signal respectively ; calculating the cross-correlation between the feedback signal and the reference signal corresponding to the delay times distributed within the preset time range to generate the cross-correlation result; and the cross-correlation result at the preset sampling frequency Sampling is performed to generate the output of the operation.

In the fifth embodiment, the cross-correlator 143 is electrically connected to the low-pass filter 141 to receive the feedback signal and the reference signal from the low-pass filter 141, and calculate the feedback signal corresponding to the reference signal The cross-correlation to the delay times distributed in the preset time zone to generate the cross-correlation result. The sampler 142 is electrically connected to the cross-correlator 143 to receive the cross-correlation result from the cross-correlator 143 , and samples the cross-correlation result at the preset sampling frequency to generate the operation output. The analog-to-digital converter 144 is electrically connected to the sampler 142 to receive the operation output from the sampler 142 , and performs analog-to-digital conversion on the operation output to generate a digital representation of the operation output for the controller 15 to receive. The controller 15 calculates the distance from the ranging system 1 to the target 2 according to the digital representation output by the operation.

Referring to Fig. 9, a sixth embodiment of the ranging system 1 of the present invention is similar to the fifth embodiment, but differs from the fifth embodiment in that: (a) the reference detector is omitted 13 (see Figure 8); (b) the controller 15 also generates a source signal of an analog signal; (c) the source terminal 11 is electrically connected to the controller 15 to receive the source signal from the controller 15, and according to the a source signal generates the incident wave; and (d) the low-pass filter 141 is configured to receive the source signal from the controller 15, and perform low-pass filtering on the source signal under the preset filtering bandwidth to generate the reference Signal.

In the description above, for purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that one or more other embodiments may be practiced without these specific details. It should be understood that references to "one embodiment", "an embodiment", an embodiment ordinal, etc. throughout the specification mean that the specific feature, structure or characteristic may be included in the practice of the invention. It should also be understood that in this specification, various features are sometimes grouped together in a single embodiment, drawing, or description thereof, in order to simplify the present invention and to facilitate understanding of various inventive aspects, and that one or more features may be used where appropriate. In some cases, specific details of one embodiment may be practiced with one or more features or specific details of another embodiment in the practice of the invention.

But the above-mentioned ones are only embodiments of the present invention, and should not limit the scope of the present invention. All simple equivalent changes and modifications made according to the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of the present invention.

1: Ranging system 11: source end 12: Feedback detector 13: Reference detector 14: calculator 141: Low-pass filter 142: Sampler 143: Cross-correlator 144:Analog to digital converter 145: Low-pass filter 146:Extractor 15: Controller 2: target

Other features and effects of the present invention will be clearly presented in the implementation manner with reference to the drawings, wherein: Figure 1 is a block diagram illustrating a first embodiment of a ranging system of the present invention; FIG. 2 is a diagram illustrating the simulated cross-correlation results of the first embodiment under different conditions with different preset filter bandwidths; Fig. 3 is a diagram illustrating the cross-correlation results of the first embodiment under different conditions of different preset sampling frequencies; FIG. 4 is a diagram illustrating cross-correlation results of the first embodiment in a coarse mode and a fine mode; Figure 5 is a block diagram illustrating a second embodiment of the ranging system according to the present invention; Figure 6 is a block diagram illustrating a third embodiment of the ranging system according to the present invention; Figure 7 is a block diagram illustrating a fourth embodiment of the ranging system according to the present invention; Figure 8 is a block diagram illustrating a fifth embodiment of the ranging system according to the present invention; and FIG. 9 is a block diagram illustrating a sixth embodiment of the ranging system according to the present invention.

1: Ranging system

11: source end

12: Feedback detector

13: Reference detector

14: calculator

141: Low-pass filter

142: Sampler

143: Cross-correlator

144:Analog to digital converter

15: Controller

2: target

Claims (12)

A ranging system adapted to measure a distance from the ranging system to a target, comprising: a source end for generating an incident wave of broadband, the incident wave is transmitted to the target, and is reflected by the target to form a reflected wave; a feedback detector for detecting the reflected wave to generate a first detection signal; An arithmetic unit is electrically connected to the feedback detector to receive the first detection signal therefrom, and is used for performing low-pass filtering on the first detected signal at an adjustable preset filtering bandwidth to generate a first filtered signal, and calculating a cross-correlation between a feedback signal derived from the first filtered signal and a reference signal corresponding to the incident wave to generate a cross-correlation result; and A controller is used for electrically connecting the computing unit to receive an operation output from the computing unit derived from the cross-correlation result, and calculate the distance from the ranging system to the target according to the operation output. The ranging system as claimed in claim 1, wherein the computing unit calculates the cross-correlation corresponding to a plurality of delay times distributed in an adjustable preset time region. The ranging system as claimed in item 1, wherein: The arithmetic unit is further used to sample the first filtered signal at an adjustable preset sampling frequency so as to generate the feedback signal; and The cross-correlation result is output as the operation. The ranging system as claimed in claim 3, wherein the preset sampling frequency is higher than the preset filtering bandwidth. The ranging system of claim 3, operable in a coarse mode and a fine mode, wherein: In the coarse mode, the controller controls the arithmetic unit in such a manner that the preset filter bandwidth and the preset sampling frequency are respectively equal to a first filter bandwidth and a first sampling frequency; and In the fine mode, the controller controls the computing unit to control the computing unit in such a way that the preset filtering bandwidth and the preset sampling frequency are respectively equal to a second filtering bandwidth and a second sampling frequency, wherein , the second filtering bandwidth is wider than the first filtering bandwidth, and the second sampling frequency is higher than the first sampling frequency. The distance measuring system as claimed in item 5, wherein: the calculator calculates the cross-correlation corresponding to a plurality of delay times distributed in an adjustable preset time zone; In the rough mode, the controller controls the arithmetic unit in such a way that the preset time zone is equal to a first time zone, and according to the calculation output, obtains the reflection wave corresponding to the incident wave in the ranging system a rough delay time; and In the fine mode, the controller controls the arithmetic unit in such a way that the preset time zone is equal to a second time zone, and according to the calculation output, obtains the reflected wave corresponding to the incident wave in the ranging system a fine delay time, and the distance from the ranging system to the target is calculated according to the fine delay time, the second time zone is narrower than the first time zone and is approximately the coarse delay time. The ranging system as claimed in claim 3, further comprising a reference detector for detecting the incident wave so as to generate a second detection signal, wherein: The arithmetic unit is also electrically connected to the reference detector to receive the second detection signal from the reference detector, and is also used for performing low-pass filtering on the second detection signal under the preset filtering bandwidth, so as to generate a second filtering signal, and The second filtered signal is sampled at the preset sampling frequency to generate the reference signal. The ranging system as claimed in claim 3, wherein: The source end is used to receive a source signal, and generate the incident wave according to the source signal; and This operator is also used to receive the source signal, and is also used to performing low-pass filtering on the source signal at the preset filtering bandwidth to generate a second filtered signal, and The second filtered signal is sampled at the preset sampling frequency to generate the reference signal. The ranging system as claimed in claim 3, wherein: The source terminal is used to receive a source signal and generate the incident wave according to the source signal; and The operator is also used to receive the source signal, and is also used to performing low-pass filtering on the source signal at the preset filtering bandwidth to generate a second filtered signal, and The second filtered signal is down-sampled to generate the reference signal corresponding to a sampling frequency equal to the preset sampling frequency. The ranging system as claimed in item 1, wherein: The first filtered signal is used as the feedback signal; and The computing unit is also set to sample the cross-correlation result at an adjustable preset sampling frequency, so as to generate a computing output. The ranging system as described in claim 10, further comprising: a reference detector for detecting the incident wave so as to generate a second detection signal; Wherein, the arithmetic unit is further electrically connected to the reference detector, so as to receive the second detection signal from the reference detector to the reference detector, and is also set to receive the second detection signal under the preset filter bandwidth. Low-pass filtering is performed in order to generate the reference signal. The ranging system as claimed in claim 10, wherein: The source terminal is used to receive a source signal and generate the incident wave according to the source signal; and The arithmetic unit is also used for receiving the source signal, and is also set to perform low-pass filtering on the source signal under the preset filter bandwidth, so as to generate the reference signal.

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