LiDAR device and its control method

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 rider device and a control method thereof. More specifically, when generating a histogram of a received signal to measure the distance to an object by transmitting and receiving a laser, the number of measurements is set differently according to the distance interval 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. The present invention relates to a rider device and a control method thereof.

Background Art

[0002] Generally, a lidar sensor irradiates light, receives a signal reflected by the irradiated light from an object to detect the object, and measures the time between the transmitted signal and the received signal to calculate the distance to the object.

[0003] Such lidar sensors have recently tended to be applied to various devices such as automobiles, drones, and robot vacuum cleaners.

[0004] In a lidar sensor, a transmitting unit that irradiates laser light and a receiving unit that receives the reflected light form a two-dimensional array. Since the transmitting and receiving units that transmit and receive light operate continuously using the entire array, power is wasted regardless of the object to be detected.

[0005] The lidar sensor has a problem that heat is generated by continuously using the entire array constituting the transmitting and receiving units.

[0006] When the entire array of the lidar sensor continues to operate continuously, problems such as acceleration of the deterioration of the lidar sensor itself and generation of noise may occur.

[0007] In addition, a 2D lidar sensor that forms a two-dimensional array is effective for object detection and distance calculation using a SPAD (Single Photon Avalanche Diode), but has problems of high light sensitivity, intense internal noise, and noise interference against outdoor light.

[0008] To address these issues, a strategy has been proposed in which the received data is measured dozens to hundreds of times to generate a histogram, and then peak values ​​are detected to determine the valid values.

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

[0010] [Patent Document 1] Korean Published Patent Publication No. 2023-0105834 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] After accumulating numerous measurements in this way to generate a histogram, the distance to the object is measured by detecting the peak value and calculating the Time of Flight (ToF).

[0012] In this case, if the number of measurements between frames is fixed at a high value to measure distant objects, measuring nearby objects will cause the histogram's peak value to saturate, making it difficult to accurately measure distances.

[0013] However, if the number of measurements between frames is fixed at a low value to allow for the measurement of nearby objects, then when measuring distant objects, there is a problem in that 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 where the number of measurements between frames is fixed, there is a problem in that the distance accuracy decreases in a specific distance range, resulting in reduced performance.

[0015] The present invention has been made to improve upon the above-mentioned problems, and in one embodiment, an object of the present invention is to provide a lidar device and a control method thereof that, when transmitting and receiving a laser to generate a histogram of a received signal in order to measure the distance to an object, sets the number of measurements to be different depending on the distance interval to the object, or sets the number of measurements by comparing the peak value of the histogram with a limit value while measuring the distance. [Means for solving the problem]

[0016] A lidar device according to one aspect of the present invention includes a transmitting / receiving module that transmits a laser signal and receives a reflected signal reflected from an object, an output module that outputs the calculated object distance, a memory that stores the number of measurements allocated for each distance interval, and a processor that is operationally coupled to the transmitting / receiving module, the output module, and the memory, wherein the processor In frame 1, The process of accumulating reflected signals received via the transmit / receive module over a set number of measurements to generate a histogram is repeated. Then, the object distance is calculated based on the peak value of the histogram and output via the output module. depending on Based on the number of measurements allocated to each distance interval, the set number of measurements is changed. Then, in the next frame, the process of generating a histogram using the changed number of measurements is repeated, Calculate object distance output via the output module. This method is characterized by repeatedly performing the process described above.

[0017] In a lidar device according to one aspect of the present invention, the number of measurements allocated to each distance interval is optimized according to the output strength of the transmitting and receiving modules, and the number of measurements increases as the distance increases.

[0018] In a lidar device according to one aspect of the present invention, the memory stores the limit peak value of the histogram, and the processor, If the cumulative number of reflected signals exceeds the set number of measurements, the peak value of the histogram is compared with the limit peak value. The system is characterized by calculating the object distance based on the histogram's peak value and outputting it via an output module if the histogram's peak value is greater than or equal to a limit peak value.

[0019] The processor compares the peak value of the histogram with the limit peak value, and if the peak value is less than the limit peak value, repeats the process of generating the histogram. vinegar It is characterized by this.

[0021] A control method for a lidar device according to an aspect of the present invention is characterized in that a processor In one frame, the process of accumulating reflected signals received via the transmit / receive module over a set number of measurements to generate a histogram is repeated for a set number of measurements. After that, the object distance is calculated based on the peak value of the histogram and output via the output module. Based on the number of measurements allocated to each distance interval according to the object distance, the set number of measurements is changed, and in the next frame, the process of generating a histogram using the changed number of measurements is repeated, after which the process of calculating the object distance and outputting it via the output module is repeated. It is characterized by this.

[0022] In a control method for a lidar device according to an aspect of the present invention, the number of measurements assigned for each distance interval is an optimized number of measurements according to the output intensity of the transmission / reception module, and the number of measurements increases as the distance gets farther. It is characterized by this.

[0023] In a control method for a lidar device according to an aspect of the present invention, the processor If the number of times the reflected signal has been accumulated exceeds the set number of measurements, the histogram will compares the peak value with the limit peak value, and if the peak value is greater than or equal to the limit peak value, calculates the object distance based on the peak value of the histogram and outputs it via the output module. It is characterized by this.

[0024] In a control method for a lidar device according to an aspect of the present invention, as a result of comparing the peak value with the limit peak value, if the peak value is less than the limit peak value, the processor repeats the process of generating the histogram. vinegar It is characterized by this.

Advantages of the Invention

[0026] A lidar device and its control method according to an aspect of the present invention, when generating a histogram of received signals to measure the distance to an object by transmitting and receiving a laser, can set the number of measurements differently according to the distance interval to the object, or set the number of measurements by comparing the peak value of the histogram with a limit value while measuring the distance, thereby not only preventing distance errors and improving performance, but also having the advantage of reducing unnecessary heat generation and power consumption of the transmission / reception module.

Brief Description of the Drawings

[0027] [Figure 1]This is a block diagram showing a lidar device according to one embodiment of the present invention. [Figure 2] This is an illustrative diagram showing a histogram generated by a lidar device according to one embodiment of the present invention. [Figure 3] This is a flowchart illustrating the control method of a lidar device according to the first embodiment of the present invention. [Figure 4] This is a flowchart illustrating a control method for a lidar device according to a second embodiment of the present invention. [Figure 5] This is a flowchart illustrating a control method for a lidar device according to a third embodiment of the present invention. [Modes for carrying out the invention]

[0028] The LiDAR device and its control method according to the present invention will be described below with reference to the attached drawings. In this process, the thickness of the lines and the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described later are defined in consideration of the function in the present invention, and these may differ depending on the intent or convention of the user or operator. Therefore, the definitions of such terms must be based on the content throughout this specification.

[0029] Figure 1 is a block diagram showing a lidar device according to one embodiment of the present invention, and Figure 2 is an illustrative diagram showing a histogram generated by the lidar device according to one embodiment of the present invention.

[0030] As shown in Figure 1, a lidar device according to one embodiment of the present invention may include a transmit / receive module 40, an output module 10, a memory 20, and a processor 30.

[0031] The transmitting / receiving module 40 can transmit a laser signal and then receive a reflected signal that is reflected off the object 50.

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

[0033] Memory 20 stores various types of software and data generated during the execution of the operating system and applications (programs or applets) for driving the LiDAR device. Memory 20 is a non-volatile memory device that retains stored information even without power, and a volatile memory device that requires power to retain stored information. Furthermore, memory 20 can temporarily or permanently store data processed by the processor 30.

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

[0035] In particular, memory 20 can store the number of measurements allocated for each distance interval, and the limit peak value of the histogram.

[0036] Here, the number of measurements allocated to each distance interval is optimized according to the output strength of the transmit / receive module 40, and the number of measurements can increase as the distance increases. At this time, the number and interval of distance intervals 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 the histogram, or it may be set arbitrarily by the user.

[0038] The processor 30 is configured to be operationally coupled to the transmit / receive module 40 and the memory 10 to control the overall operation of the lidar device, and this can be implemented as an integrated circuit or a system.

[0039] In other words, the processor 30 operates the transmit / receive module 40 frame by frame to measure the distance to the object, generates a laser signal and transmits it to the object 50, and then receives the reflected signal reflected from the object 50 via the transmit / receive module 40. This process is repeated, and the object distance can be calculated using the Time of Flight (TF) value, which is the difference between the transmission time of the laser signal and the reception time of the reflected signal, and output via the output module 10.

[0040] To explain this in more detail, firstly, as a first method, the processor 30 can accumulate the reflected signals received via the transmit / receive module 40 over a set number of measurement intervals per frame, and repeat the process of generating a histogram as shown in Figure 2.

[0041] Based on the peak values ​​of the histogram accumulated over the number of measurements set in this frame-by-frame manner, the processor 30 can calculate the object distance and output it via the output module 10.

[0042] Subsequently, the processor 30 can change the set number of measurements based on the number of measurements allocated to each distance interval stored in the memory 20 based on the calculated object distance, and then in the next frame, generate a histogram based on the changed number of measurements and calculate the object distance.

[0043] By varying the number of measurements set in this way for each distance interval 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 transmit / receive module 40 on a frame-by-frame basis and repeats the histogram generation process. If the peak value of the histogram is greater than or equal to a limit peak value, the processor 30 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 is reached, the difficulty in distance measurement that arises when the peak value saturates or is not sufficiently maintained can be eliminated.

[0046] On the other hand, as a third method, the processor 30 can repeatedly accumulate the reflected signals received via the transmit / receive module 40 over a set number of measurement intervals per frame, thereby generating a histogram as shown in Figure 2.

[0047] Subsequently, the processor compares the peak value of the generated histogram with the limit peak value. If the peak value is less than the limit peak value, it repeats the histogram generation process to accumulate additional reflected signals and ensure a sufficient peak value for the histogram. After comparing the peak value with the limit peak value, if the peak value is greater than or equal to the limit peak value, the processor can calculate and output the object distance based on the peak value of the histogram.

[0048] Subsequently, the processor 30 can change the set number of measurements based on the number of measurements allocated to each distance interval stored in the memory 20 based on the calculated object distance, and then in the next frame, generate a histogram based on the changed number of measurements and calculate the object distance.

[0049] By varying the number of measurements set in this way for each distance interval according to the object distance, it is possible not only to solve the problem of reduced distance accuracy in a particular distance range, but also to improve the accuracy of distance measurement by repeatedly generating a histogram during the set number of measurements, and then taking additional measurements if the peak value is insufficient.

[0050] As described above, the LiDAR device according to the embodiment of the present invention has the advantage of not only preventing distance errors and improving performance when generating a histogram of the received signal to measure the distance to an object by transmitting and receiving a laser, by setting the number of measurements to be different depending on the distance interval to the object, or by setting the number of measurements by comparing the peak value of the histogram with a limit value while measuring the distance, but also by reducing unnecessary heat generation and power consumption of the transmitting and receiving module.

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

[0052] As shown in Figure 3, in the control method of the lidar device according to the first embodiment of the present invention, first, the processor 30 activates the transmitting and receiving 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 object 50 in step S310, the processor 30 receives the reflected signal from object 50 via the transmit / receive module 40, accumulates it, and generates a histogram as shown in Figure 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 the set number of measurements (S330).

[0055] In step S330, the number of measurements is compared with the set number of measurements. If the number of measurements does not exceed the set number of measurements, the processor 30 returns to step S310 and repeats the process of generating the histogram.

[0056] In response to this, in step S330, the number of measurements is compared with the set number of measurements. If the number of measurements exceeds the set number of measurements, the processor 30 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 allocated to each distance interval stored in the memory 20 based on the calculated object distance (S350).

[0058] Here, the number of measurements allocated to each distance interval is optimized according to the output strength of the transmit / receive module 40, and the number of measurements can increase as the distance increases. At this time, the number and interval of distance intervals can be set differently according to user definition.

[0059] By varying the number of measurements set in this way for each distance interval 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] Figure 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 Figure 4, in the control method for the lidar device according to the second embodiment of the present invention, first, the processor 30 activates the transmitting / receiving 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 object 50 in step S410, the processor 30 receives the reflected signal from object 50 via the transmit / receive module 40, accumulates it, and generates a histogram as shown in Figure 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 the histogram, or it may be set arbitrarily by the user.

[0065] In step S430, the peak value of the histogram is compared with the limit peak value. If the peak value of the histogram is less than the limit peak value, the processor 30 returns to step S410 and repeats the process of generating the histogram.

[0066] In response to this, if the peak value of the histogram in step S430 is greater than or equal to the limit peak value, 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] By calculating the object distance based on the peak values ​​of the histogram generated in this way, once the set peak limit is reached, the difficulty in distance measurement that arises when peak values ​​saturate or are not sufficiently secured can be overcome.

[0068] Figure 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 Figure 5, in the control method for the lidar device according to the third embodiment of the present invention, first, the processor 30 activates the transmitting / receiving 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 object 50 in step S510, the processor 30 receives the reflected signal from object 50 via the transmit / receive module 40, accumulates it, and generates a histogram as shown in Figure 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 the set number of measurements (S530).

[0072] In step S530, the number of measurements is compared with the set number of measurements. If the number of measurements does not exceed the set number of measurements, the processor 30 returns to step S510 and repeats the process of generating the histogram.

[0073] In response to this, in step S530, the number of measurements is compared with the set number of measurements. 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 the histogram, or it may be set arbitrarily by the user.

[0075] In step S540, the peak value of the histogram is compared with the limit peak value. If the peak value of the histogram is less than the limit peak value, the processor 30 returns to step S510 and repeats the process of generating the histogram.

[0076] In response to this, if the peak value of the histogram in step S540 is greater than or equal to the limit peak value, 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 allocated to each distance interval stored in the memory 20 based on the calculated object distance (S560).

[0078] By varying the number of measurements set in this way for each distance interval according to the object distance, it is possible not only to solve the problem of reduced distance accuracy in a particular distance range, but also to improve the accuracy of distance measurement by repeatedly generating a histogram during the set number of measurements, and then taking additional measurements if the peak value is insufficient.

[0079] As described above, the control method for a lidar device according to an embodiment of the present invention has the advantage of not only preventing distance errors and improving performance when generating a histogram of the received signal to measure the distance to an object by transmitting and receiving a laser, by setting the number of measurements to be different depending on the distance interval to the object, or by setting the number of measurements by comparing the peak value of the histogram with a limit value while measuring the distance, but also by reducing unnecessary heat generation and power consumption of the transmitting and receiving module.

[0080] The realizations described herein can be realized, for example, by method or process, apparatus, software program, data stream or signal. Even if discussed only in the context of a single form of realization (e.g., discussed only in the context of a method), the realization of the discussed feature can also be realized in other forms (e.g., apparatus or program). Apparatus can be realized by appropriate hardware, software and firmware, etc. Methods may be realized by apparatus such as a processor, which is a processing device generally referred to as a computer, microprocessor, integrated circuit or programmable logic device, etc. Processors also include communication devices such as computers, mobile phones, portable / personal information terminals (PDAs: Personal Digital Assistants) and other devices that facilitate the communication of information between end users.

[0081] The present invention has been described with reference to the embodiments shown in the drawings, which are merely illustrative, and a person with ordinary skill in the art will understand that a variety of modifications and equivalent other embodiments are possible therefrom.

[0082] Therefore, the true scope of technical protection of the present invention must be defined by the claims. [Explanation of Symbols]

[0083] 10: Output Module 20: Memory 30: Processor 40: Transceiver module 50:Object

Claims

1. A transmitting and receiving module that transmits a laser signal and then receives the reflected signal reflected from an object, An output module that outputs the calculated object distance, A memory that stores the number of measurements allocated for each distance interval, The system includes a processor operationally coupled to the aforementioned transmitting / receiving module, the output module, and the memory, The LiDAR device is characterized in that, in one frame, the processor repeatedly performs the process of accumulating the reflected signals received via the transmitting / receiving module during a set number of measurements to generate a histogram, then calculates the object distance based on the peak value of the histogram and outputs it via the output module, changes the set number of measurements based on the number of measurements allocated to each distance interval according to the object distance, and in the next frame, repeats the process of generating the histogram using the changed number of measurements, then calculates the object distance and outputs it via the output module.

2. The LiDAR device according to claim 1, characterized in that the number of measurements allocated to each distance interval is optimized according to the output strength of the transmitting and receiving module, and the number of measurements increases as the distance increases.

3. The memory stores the limit peak value of the histogram, The LiDAR device according to claim 1, characterized in that, if the number of times the reflected signal has been accumulated exceeds the set number of measurements, the processor compares the peak value of the histogram with the limit peak value, and if the peak value of the histogram is equal to or greater than the limit peak value, calculates the object distance based on the peak value of the histogram and outputs it via the output module.

4. The lidar device according to claim 3, characterized in that the processor compares the peak value of the histogram with the limit peak value, and if the peak value is less than the limit peak value, repeats the process of generating the histogram.

5. A control method for a lidar device, characterized in that the processor, in one frame, repeats the process of accumulating reflected signals received via a transmit / receive module during a set number of measurement intervals to generate a histogram for a set number of measurement intervals, calculates the object distance based on the peak value of the histogram and outputs it via an output module, changes the set number of measurement intervals based on the number of measurement intervals allocated to each distance interval according to the object distance, and in the next frame, repeats the process of generating the histogram using the changed number of measurement intervals, calculates the object distance and outputs it via the output module, and repeats this process.

6. The control method for a lidar device according to claim 5, characterized in that the number of measurements allocated to each distance interval is optimized according to the output strength of the transmitting and receiving module, and the number of measurements increases as the distance increases.

7. The control method for a lidar device according to claim 5, characterized in that, if the number of times the reflected signal has been accumulated exceeds the set number of measurements, the processor compares the peak value of the histogram with the limit peak value, and if the peak value is equal to or greater than the limit peak value, calculates the object distance based on the peak value of the histogram and outputs it via the output module.

8. The control method for a lidar device according to claim 7, characterized in that the processor, as a result of comparing the peak value with the limit peak value, repeats the process of generating the histogram if the peak value is less than the limit peak value.

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