Lidar apparatus and control method thereof

Abstract

To provide a lidar apparatus and a control method thereof.SOLUTION: The lidar apparatus includes: a transmission and reception module transmitting a laser signal and receiving a reflected signal reflected from an object; an output module outputting a calculated object distance; a memory storing a measurement count allocated to each distance range; and a processor operatively coupled to the transmission and reception module, the output module, and the memory. After repeating a process of generating a histogram by accumulating the reflected signals received through the transmission and reception module for a set measurement count, the processor calculates an object distance based on a peak value of the histogram and outputs it through the output module, and then modifies the set measurement count based on the measurement count allocated to each distance range based on the object distance so as to repeat the process of calculating the object distance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a LIDAR device and a control method thereof, and more particularly to a LIDAR device and a control method thereof, in which, when a histogram of a received signal is generated to transmit and receive a laser and measure a distance to an object, the number of measurements is set differently depending on a distance range to the object, or the number of measurements is set by comparing a peak value of the histogram with a limit value while measuring the distance. [Background technology]

[0002] Generally, a LiDAR sensor detects objects by emitting light and receiving a signal that is reflected from the object, and calculates the distance to the object by measuring the time between the transmitted and received signals.

[0003] Recently, such lidar sensors have been increasingly applied to a variety of devices, such as automobiles, drones, and robot vacuum cleaners.

[0004] In a lidar sensor, a transmitter that emits laser light and a receiver that receives reflected light form a two-dimensional array. Since the transmitter and receiver that transmit and receive light continuously operate using the entire array, the lidar sensor wastes power regardless of the object to be detected.

[0005] A problem with the lidar sensor is that heat is generated due to continuous use of the entire array that constitutes the transmitter / receiver.

[0006] If the entire array of the lidar sensor is continuously operated, the deterioration of the lidar sensor itself may accelerate, and problems such as noise may occur.

[0007] In addition, 2D lidar sensors that form a two-dimensional array are effective in detecting objects and calculating distances using SPADs (Single Photon Avalanche Diodes), but they have problems with high light sensitivity, resulting in severe internal noise and noise interference from outdoor light.

[0008] In order to solve this problem, a method has been proposed in which received data is measured several tens to several hundreds of times to generate a histogram, and then a peak value is detected to determine a valid value.

[0009] The background art of the present invention is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 2023-0105834 Summary of the Invention [Problem to be solved by the invention]

[0011] In this way, a large number of measured values ​​are accumulated to generate a histogram, and the distance to the object is measured by detecting the peak value and calculating the ToF (Time of Flight).

[0012] In this case, if the number of measurements between frames is fixed to a high value in order to measure a distant object, when measuring a close object, the peak value of the histogram becomes saturated, making it difficult to measure the distance accurately.

[0013] However, if the number of measurements between frames is fixed to a low value so that close objects can be measured, when measuring objects at a distance, the peak value of the histogram is not sufficiently secured, making it difficult to measure the distance.

[0014] In the case of a LIDAR device in which the number of measurements between frames is fixed, there is a problem in that the distance accuracy in a specific distance range decreases, resulting in degraded performance.

[0015] The present invention has been made to solve the above problems, and an object of the present invention in one aspect is to provide a LIDAR device and a control method thereof, in which when a histogram of a received signal is generated to transmit and receive laser and measure the distance to an object, the number of measurements is set differently depending on a distance range to the object, or the number of measurements is set by comparing the peak value of the histogram with a limit value while measuring the distance. [Means for solving the problem]

[0016] According to one aspect of the present invention, a LIDAR device includes a transceiver module that transmits a laser signal and receives a reflected signal reflected from an object, an output module that outputs a calculated object distance, a memory that stores a measurement number assigned to each distance interval, and a processor operatively coupled to the transceiver module, the output module, and the memory. The processor repeats a process of accumulating the reflected signals received through the transceiver module for a set measurement number to generate a histogram, calculates the object distance based on a peak value of the histogram and outputs it through the output module, and repeatedly calculates the object distance by changing the set measurement number based on the measurement number assigned to each distance interval based on the object distance.

[0017] In a LIDAR device according to one aspect of the present invention, the number of measurements assigned to each distance section is optimized according to the output strength of the transceiver module, and is characterized in that the number of measurements increases as the distance increases.

[0018] According to another aspect of the present invention, a LIDAR device includes a transceiver module that transmits a laser signal and then receives a reflected signal reflected from an object, an output module that outputs a calculated object distance, a memory that stores a limit peak value of a histogram, and a processor operatively coupled to the transceiver module, the output module, and the memory. The processor accumulates the reflected signals received through the transceiver module to repeat a process of generating a histogram, and if the peak value of the histogram is equal to or greater than the limit peak value, calculates an object distance based on the peak value of the histogram and outputs the calculated object distance through the output module.

[0019] According to yet another aspect of the present invention, there is provided a LIDAR device including: a transceiver module that transmits a laser signal and receives a reflected signal reflected from an object; an output module that outputs a calculated object distance; a memory that stores a measurement number assigned to each distance section and a limit peak value of a histogram; and a processor operatively coupled to the transceiver module, the output module, and the memory. The processor repeats a process of accumulating the reflected signal received through the transceiver module for a set measurement number to generate a histogram, compares a peak value of the histogram with a limit peak value, and if the peak value is less than the limit peak value, repeats the process of generating the histogram, and calculates an object distance based on the peak value of the histogram and outputs the calculated object distance through the output module.

[0020] In a LIDAR device according to still another aspect of the present invention, the processor changes the set number of measurements based on the number of measurements assigned to each distance interval based on the object distance.

[0021] A method for controlling a LIDAR device according to one aspect of the present invention includes the steps of: a processor accumulating reflected signals received via a transceiver module to generate a histogram; a processor repeating the process of generating the histogram for a set number of measurements; a processor repeatedly generating the histogram for the set number of measurements, and then calculating and outputting an object distance based on a peak value of the histogram; and a processor changing the set number of measurements based on the number of measurements assigned to each distance interval based on the object distance.

[0022] In a method for controlling a LIDAR device according to one aspect of the present invention, the number of measurements assigned to each distance section is optimized according to the output strength of the transceiver module, and is characterized in that the number of measurements increases as the distance increases.

[0023] A control method for a LIDAR device according to another aspect of the present invention is characterized in that it includes the steps of: a processor accumulating reflected signals received via a transceiver module and repeating a process of generating a histogram; a processor comparing a peak value of the histogram with a restricted peak value while repeating the process of generating the histogram; and a processor calculating and outputting an object distance based on the peak value of the histogram when the peak value is equal to or greater than the restricted peak value as a result of comparing the peak value with the restricted peak value.

[0024] A method for controlling a LIDAR device according to yet another aspect of the present invention includes the steps of: a processor accumulating reflected signals received via a transceiver module to generate a histogram; a processor repeating the process of generating the histogram for a set number of measurements; a processor comparing a peak value of the histogram with a limited peak value after repeatedly generating the histogram for the set number of measurements; a processor repeating the process of generating the histogram if the peak value is less than the limited peak value as a result of comparing the peak value with the limited peak value; and a processor calculating and outputting an object distance based on the peak value of the histogram if the peak value is equal to or greater than the limited peak value as a result of comparing the peak value with the limited peak value.

[0025] According to yet another aspect of the present invention, a method for controlling a LIDAR device further includes a step of changing a set number of measurements based on a number of measurements assigned to each distance interval based on an object distance by a processor. Effect of the Invention

[0026] In accordance with one aspect of the present invention, when a histogram of a received signal is generated to transmit and receive laser and measure the distance to an object, the LIDAR device and control method thereof can set the number of measurements differently depending on the distance range from the object, or set the number of measurements by comparing the peak value of the histogram with a limit value while measuring the distance. This not only prevents distance errors and improves performance, but also has the advantage of reducing unnecessary heat generation and power consumption in the transceiver module. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a block diagram showing a LIDAR device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exemplary diagram showing a histogram generated by a LIDAR device according to an embodiment of the present invention. [Diagram 3]4 is a flowchart illustrating a control method for a LIDAR device according to the first embodiment of the present invention. [Figure 4] 10 is a flowchart illustrating a control method for a LIDAR device according to a second embodiment of the present invention. [Diagram 5] 13 is a flowchart illustrating a control method for a LIDAR device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a LIDAR device and a control method thereof according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of lines and the size of components shown in the drawings may be exaggerated for clarity and convenience of the description. In addition, the terms used below are defined in consideration of the functions of the present invention, and may differ depending on the intention or practice of a user or operator. Therefore, the definitions of such terms should be based on the contents of this specification as a whole.

[0029] FIG. 1 is a block diagram showing a LIDAR device according to an embodiment of the present invention, and FIG. 2 is an example diagram showing a histogram generated by the LIDAR device according to an embodiment of the present invention.

[0030] As shown in FIG. 1 , a LIDAR device according to one embodiment of the present invention may include a transceiver module 40, an output module 10, a memory 20, and a processor 30.

[0031] The transceiver module 40 can transmit a laser signal and then receive a reflected signal reflected by the object 50 .

[0032] The output module 10 can output a ToF (Time of Flight) value of the object distance calculated by the LIDAR device.

[0033] The memory 20 stores various types of software and data generated during the execution of an operating system and applications (programs or applets) for driving the lidar device. At this time, the memory 20 is generally referred to as a non-volatile storage device that continues to hold stored information even when power is not supplied, and a volatile storage device that requires power to hold stored information. The memory 20 can also function to temporarily or permanently store data processed by the processor 30.

[0034] Here, memory 20 may include a volatile storage device that requires power to retain stored information, as well as a magnetic storage media or a flash storage media, although the scope of the present invention is not limited in this respect.

[0035] In particular, the memory 20 can store the number of measurements assigned to each distance section, or can store the limit peak value of a histogram.

[0036] Here, the number of measurements assigned to each distance section is optimized according to the output strength of the transceiver module 40, and the number of measurements can be increased as the distance increases. At this time, the number and intervals of the distance sections can be set differently according to user definition.

[0037] On the other hand, the limit peak value may be set to a saturation value that can be processed when the processor 30 generates a histogram, or may be arbitrarily set by the user.

[0038] The processor 30 is operatively coupled to the transceiver module 40 and the memory 10 to control the overall operation of the LIDAR device, and can be realized as an integrated circuit or a system.

[0039] That is, the processor 30 operates the transceiver module 40 in frame units to measure the distance to the object, generates a laser signal, transmits it to the object 50, and then repeats the process of receiving the reflected signal reflected by the object 50 via the transceiver module 40, thereby calculating the object distance using a ToF value based on the difference between the transmission time of the laser signal and the reception time of the reflected signal, and outputting the calculated distance via the output module 10.

[0040] To explain this in more detail, first, as a first method, the processor 30 can repeat the process of accumulating the reflected signals received through the transceiver module 40 for a set number of measurements in frame units and generating a histogram as shown in Figure 2.

[0041] Based on the peak value of the histogram accumulated during the number of measurements set in this manner in frame units, the processor 30 can calculate the object distance and output it via the output module 10 .

[0042] Thereafter, the processor 30 changes the set number of measurements based on the number of measurements assigned to each distance section stored in the memory 20 based on the calculated object distance, and then generates a histogram based on the changed number of measurements in the next frame to calculate the object distance.

[0043] By varying the number of measurements set in this way for each distance section according to the object distance, the problem of reduced distance accuracy in a specific distance range can be solved and reliability can be improved.

[0044] Next, as a second method, the processor 30 accumulates the reflected signals received via the transceiver module 40 on a frame-by-frame basis to repeat the process of generating a histogram, and if the peak value of the histogram is greater than or equal to the limited peak value, it can calculate and output the object distance based on the peak value of the histogram.

[0045] In other words, by calculating the object distance based on the peak value of the generated histogram when a set peak limit value is reached, it is possible to eliminate difficulties in distance measurement that arise when the peak value becomes saturated or is not sufficiently secured.

[0046] Meanwhile, as a third method, the processor 30 may repeat the process of accumulating the reflected signals received through the transceiver module 40 for a set number of measurements in frame units and generating a histogram as shown in FIG. 2.

[0047] Thereafter, the processor compares the peak value of the generated histogram with the restricted peak value, and if the peak value is less than the restricted peak value, repeats the process of generating the histogram and accumulates additional reflected signals to ensure a sufficient peak value of the histogram, and if the peak value is equal to or greater than the restricted peak value as a result of comparing the peak value with the restricted peak value, the processor can calculate and output the object distance based on the peak value of the histogram.

[0048] Thereafter, the processor 30 changes the set number of measurements based on the number of measurements assigned to each distance section stored in the memory 20 based on the calculated object distance, and then generates a histogram based on the changed number of measurements in the next frame to calculate the object distance.

[0049] By varying the number of measurements set in this manner for each distance section according to the object distance, not only is it possible to solve the problem of reduced distance accuracy in a specific distance region, but also to increase the accuracy of distance measurement by performing additional measurements if the peak value is not sufficient after repeatedly generating a histogram for the set number of measurements.

[0050] As described above, according to the LIDAR device according to the embodiment of the present invention, when a histogram of a received signal is generated to transmit and receive a laser and measure the distance to an object, the number of measurements is set differently depending on the distance range to the object, or the peak value of the histogram is compared with a limit value while measuring the distance to set the number of measurements, thereby preventing distance errors and improving performance, and having the advantage of reducing unnecessary heat generation and power consumption of the transceiver module.

[0051] FIG. 3 is a flowchart illustrating the control method of the LIDAR device according to the first embodiment of the present invention.

[0052] As shown in FIG. 3, in the control method for a LIDAR device according to the first embodiment of the present invention, first, the processor 30 activates the transceiver module 40 to measure the distance to the object 50 and transmits a laser signal to the object 50 (S310).

[0053] After transmitting a laser signal to the object 50 in step S310, the processor 30 receives the reflected signal reflected by the object 50 via the transceiver module 40, accumulates the received signal, and generates a histogram as shown in FIG. 2 (S320).

[0054] After generating the histogram in step S320, the processor 30 counts the number of measurements and determines whether the number of measurements exceeds a set number of measurements (S330).

[0055] In step S330, the processor 30 compares the number of measurements with the set number of measurements, and if the number of measurements does not exceed the set number of measurements, the processor 30 returns to step S310 to repeat the process of generating a histogram.

[0056] In contrast, in step S330, the processor 30 compares the number of measurements with the set number of measurements, and if the number of measurements exceeds the set number of measurements, calculates the object distance based on the peak value of the histogram and outputs it via the output module 10 (S340).

[0057] After calculating and outputting the object distance on a frame-by-frame basis in step S340, the processor 30 changes the set number of measurements based on the number of measurements assigned to each distance section stored in the memory 20 based on the calculated object distance (S350).

[0058] Here, the number of measurements assigned to each distance section is optimized according to the output strength of the transceiver module 40, and the number of measurements can be increased as the distance increases. At this time, the number and intervals of the distance sections can be set differently according to user definition.

[0059] By varying the number of measurements set in this way for each distance section according to the object distance, the problem of reduced distance accuracy in a specific distance range can be solved and reliability can be improved.

[0060] FIG. 4 is a flowchart illustrating a control method for a LIDAR device according to a second embodiment of the present invention.

[0061] As shown in FIG. 4, in the control method for a LIDAR device according to the second embodiment of the present invention, first, the processor 30 activates the transceiver module 40 to measure the distance to the object 50 and transmits a laser signal to the object 50 (S410).

[0062] After transmitting a laser signal to the object 50 in step S410, the processor 30 receives the reflected signal reflected by the object 50 via the transceiver module 40, accumulates the received signal, and generates a histogram as shown in FIG. 2 (S420).

[0063] After generating the histogram in step S420, the processor 30 compares the peak value of the histogram with the limit peak value (S430).

[0064] Here, the limit peak value may be set to a saturation value that can be processed when the processor 30 generates a histogram, or may be arbitrarily set by the user.

[0065] If the peak value of the histogram is less than the limit peak value as a result of comparing the peak value of the histogram with the limit peak value in step S430, the processor 30 returns to step S410 to repeat the process of generating a histogram.

[0066] On the other hand, if the peak value of the histogram is equal to or greater than the limit peak value in step S430, the processor 30 calculates the object distance based on the peak value of the histogram and outputs it via the output module 10 (S440).

[0067] Based on the peak value of the histogram generated in this manner, if a set peak limit value is reached, the object distance is calculated based on the peak value, thereby eliminating the difficulties in distance measurement that arise when the peak value becomes saturated or is not sufficiently secured.

[0068] FIG. 5 is a flowchart illustrating a control method for a LIDAR device according to a third embodiment of the present invention.

[0069] As shown in FIG. 5, in the control method for a LIDAR device according to the third embodiment of the present invention, first, the processor 30 activates the transceiver module 40 to measure the distance to the object 50 and transmits a laser signal to the object 50 (S510).

[0070] After transmitting a laser signal to the object 50 in step S510, the processor 30 receives the reflected signal reflected by the object 50 via the transceiver module 40, accumulates the received signal, and generates a histogram as shown in FIG. 2 (S520).

[0071] After generating the histogram in step S520, the processor 30 counts the number of measurements and determines whether the number of measurements exceeds a set number of measurements (S530).

[0072] In step S530, the processor 30 compares the number of measurements with the set number of measurements, and if the number of measurements does not exceed the set number of measurements, the processor 30 returns to step S510 to repeat the process of generating a histogram.

[0073] On the other hand, in step S530, the processor 30 compares the number of measurements with the set number of measurements, and if the number of measurements exceeds the set number of measurements, the processor 30 compares the peak value of the histogram with the limit peak value (S540).

[0074] Here, the limit peak value may be set to a saturation value that can be processed when the processor 30 generates a histogram, or may be arbitrarily set by the user.

[0075] If the peak value of the histogram is less than the limit peak value as a result of comparing the peak value of the histogram with the limit peak value in step S540, the processor 30 returns to step S510 to repeat the process of generating a histogram.

[0076] On the other hand, if the peak value of the histogram is equal to or greater than the limit peak value in step S540, the processor 30 calculates the object distance based on the peak value of the histogram and outputs it via the output module 10 (S550).

[0077] After calculating and outputting the object distance on a frame-by-frame basis in step S550, the processor 30 changes the set number of measurements based on the number of measurements assigned to each distance section stored in the memory 20 based on the calculated object distance (S560).

[0078] By varying the number of measurements set in this manner for each distance section according to the object distance, not only is it possible to solve the problem of reduced distance accuracy in a specific distance region, but also to increase the accuracy of distance measurement by performing additional measurements if the peak value is not sufficient after repeatedly generating a histogram for the set number of measurements.

[0079] As described above, according to the control method of a LIDAR device according to an embodiment of the present invention, when a histogram of a received signal is generated to transmit and receive a laser and measure the distance to an object, the number of measurements is set differently depending on a distance range from the object, or the peak value of the histogram is compared with a limit value while measuring the distance to set the number of measurements. This has the advantage of preventing distance errors and improving performance as well as reducing unnecessary heat generation and power consumption of the transceiver module.

[0080] The implementations described herein may be implemented, for example, in a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed only in the context of a single implementation (e.g., discussed only in a method), the implementation of the discussed features may also be implemented in other forms (e.g., an apparatus or a program). An apparatus may be implemented in appropriate hardware, software, firmware, and the like. A method may be implemented in an apparatus such as, for example, a processor, which generally refers to a processing device including a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices such as computers, mobile phones, portable / personal digital assistants (PDAs), and other devices that facilitate communication of information between end users.

[0081] The present invention has been described with reference to the embodiments shown in the drawings, but this is by way of example only, and those skilled in the art will recognize that various modifications and equivalent alternative embodiments are possible.

[0082] Therefore, the true technical scope of the present invention should be defined by the appended claims. [Explanation of symbols]

[0083] 10: Output module 20: Memory 30: Processor 40: Transmitting and receiving module 50:Object

Claims

1. a transceiver module for transmitting a laser signal and then receiving a reflected signal reflected by an object; an output module for outputting the calculated object distance; a memory for storing the number of measurements assigned to each distance section; a processor operatively coupled to the transceiver module, the output module, and the memory; the processor repeats a process of accumulating the reflected signals received through the transceiver module for a set number of measurements to generate a histogram, calculates an object distance based on a peak value of the histogram and outputs the histogram through the output module, and repeats a process of changing the set number of measurements based on the number of measurements assigned to each distance section based on the object distance to calculate the object distance.

2. 2. The LIDAR device of claim 1, wherein the number of measurements assigned to each distance section is optimized according to an output strength of the transceiver module, and the number of measurements increases as the distance increases.

3. a transceiver module for transmitting a laser signal and then receiving a reflected signal reflected by an object; an output module for outputting the calculated object distance; a memory for storing a limit peak value of the histogram; a processor operatively coupled to the transceiver module, the output module, and the memory; the processor accumulates the reflected signals received through the transceiver module and repeats the process of generating the histogram, and if a peak value of the histogram is greater than or equal to the limited peak value, calculates the object distance based on the peak value of the histogram and outputs the calculated object distance through the output module.

4. a transceiver module for transmitting a laser signal and then receiving a reflected signal reflected by an object; an output module for outputting the calculated object distance; a memory for storing the number of measurements and the limit peak value of the histogram assigned to each distance section; a processor operatively coupled to the transceiver module, the output module, and the memory; the processor repeats a process of accumulating the reflected signals received through the transceiver module for a set number of measurements to generate the histogram, and then compares a peak value of the histogram with the limited peak value. If the peak value is less than the limited peak value, the processor repeats the process of generating the histogram. If the peak value is equal to or greater than the limited peak value as a result of comparing the peak value with the limited peak value, the processor calculates the object distance based on the peak value of the histogram and outputs the calculated object distance via the output module.

5. The LIDAR device of claim 4 , wherein the processor changes the set number of measurements based on a number of measurements assigned to each distance interval based on the object distance.

6. A processor accumulates the reflected signals received via the transceiver module to generate a histogram; The processor repeats the process of generating the histogram for a set number of measurements; The processor repeatedly generates the histogram during the set number of measurements, and then calculates an object distance based on a peak value of the histogram and outputs the calculated object distance via an output module; and changing the set number of measurements based on a number of measurements assigned to each distance interval based on the object distance by the processor.

7. 7. The method of claim 6, wherein the number of measurements assigned to each distance section is optimized according to the output strength of the transceiver module, and the number of measurements increases as the distance increases.

8. A processor repeats a process of accumulating the reflected signals received via the transceiver module and generating a histogram; the processor repeats the process of generating the histogram and compares the peak value of the histogram with a limit peak value; and if the processor compares the peak value with the restricted peak value and the peak value is greater than or equal to the restricted peak value, calculating an object distance based on the peak value of the histogram and outputting the calculated object distance via an output module.

9. A processor accumulates the reflected signals received via the transceiver module to generate a histogram; The processor repeats the process of generating the histogram for a set number of measurements; the processor repeatedly generates the histogram for the set number of measurements, and then compares a peak value of the histogram with a limit peak value; repeating the process of generating the histogram when the peak value is less than the limiting peak value as a result of the processor comparing the peak value with the limiting peak value; and if the processor compares the peak value with the restricted peak value and the peak value is greater than or equal to the restricted peak value, calculating an object distance based on the peak value of the histogram and outputting the calculated object distance via an output module.

10. 10. The method of claim 9, further comprising: changing the set number of measurements based on a number of measurements assigned to each distance interval based on the object distance.

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