LASER SENSOR, OBJECT TRACKING SYSTEM AND OBJECT TRACKING

Abstract

A laser sensor (110) comprises a first main laser (111) for emitting laser light of a first wavelength, a second main laser (112) for emitting laser light of a second wavelength, a dummy laser (113) for emitting laser light of a third wavelength, a first light-receiving element (114) sensitive to light of the first wavelength, and a second light-receiving element that is the light-receiving element sensitive to light of the second wavelength. The first main laser and the second main laser emit the laser light alternately.

Description

Technical field

[0001] The present disclosure relates to object detection using lasers. Background on the state of the art

[0002] The measurement using LiDAR includes the measurement using the ToF principle.

[0003] LiDAR is an abbreviation for Light Detection and Ranging.

[0004] ToF is an abbreviation for Time of Flight.

[0005] Measurement using the ToF principle refers to a method for calculating a distance based on a time interval from the emission of the laser light until the reception of the laser light, which is reflected after striking a subject (reflected light), by a sensor.

[0006] LiDARs primarily use near-infrared light with a wavelength of 903 or 905 nanometers. A LiDAR with a wavelength of 1550 nanometers has also been developed. The longer the wavelength, the farther the measurement can reach.

[0007] In a 900-nanometer LiDAR, silicon (Si) is used as the light receiving element.

[0008] In a 1550-nanometer LiDAR, indium gallium arsenide (InGaAs) is used as the light receiving element.

[0009] A well-known attack on infrared sensors that measure the surrounding environment, such as LiDAR, is a spoofing attack that uses a fake reflection wave. Countermeasures against this spoofing attack include redundancy and sensor fusion.

[0010] However, one known attack against self-driving cars is an attack that deceives the processing of object detection signals of a sensor fusion using a camera and a LiDAR.

[0011] Therefore, it is important to implement not only countermeasures through sensor fusion using multiple sensors, but also countermeasures against attacks on individual sensors.

[0012] Known countermeasures against attacks on sensors include random modulation, the use of multiple wavelengths, and narrowing the light reception angle.

[0013] Although FMCW LiDARs are designed with random modulation, rotation is difficult, resulting in a narrow measurement range. Multiple LiDARs are required to perform a 360-degree measurement, making them unsuitable for compact devices like drones.

[0014] The use of multiple wavelengths enables cost-effective attacks for attackers using multiple wavelengths.

[0015] Narrowing the light reception angle can reduce the scope for attacks. However, this requires installing multiple LiDARs, which is costly. There are use cases where a cost-effective countermeasure against sensor attacks is needed without increasing the number of LiDARs.

[0016] Patent literature 1 discloses a countermeasure against deception attacks on sensors. In this countermeasure, deceptive signals are prepared and an attacker is tricked into mistaking the deceptive signals for genuine measurement signals and attacking them. Reference list patent literature

[0017] Patent Literature 1: JP H9-281397 A Summary of the invention: Technical problem

[0018] Conventional countermeasures against spoofing attacks require multiple LiDARs and cannot be applied to small devices like UAVs. Additionally, they incur financial and technical costs.

[0019] UAV is an abbreviation for unmanned aerial vehicle.

[0020] No countermeasures were proposed against attacks that deceive the signal processing of sensor fusion.

[0021] One objective of the present disclosure is to prevent faulty object detection under the influence of a spoofing attack. Solution to the problem

[0022] A laser sensor of the present disclosure comprises a main laser for emitting laser light of a specific wavelength; a dummy laser for emitting laser light with a wavelength different from the specific wavelength; and a light-receiving element that is sensitive to light of a specific wavelength. Advantageous effects of the invention

[0023] According to the present disclosure, it is possible to prevent faulty object detection under the influence of a spoofing attack. Brief description of the drawings Fig. Figure 1 is a configuration diagram of an object detection system 100 in embodiment 1. Fig. Figure 2 is a configuration diagram of a laser sensor 110 in embodiment 1. Fig. Figure 3 is a configuration diagram of an attack detection device 120 in embodiment 1. Fig. Figure 4 is a configuration diagram of an object detection device 130 in embodiment 1. Fig. Figure 5 is a functional configuration diagram of the object detection system 100 in embodiment 1. Fig. Figure 6 is a flowchart of an object detection method in embodiment 1. Fig. Figure 7 is a flowchart of the object detection method in embodiment 1. Description of embodiments

[0024] In the embodiments and drawings, identical or corresponding elements are designated with the same reference numerals. The description of an element designated with the same reference numeral as an element already described is omitted or simplified as appropriate. Arrows in diagrams primarily indicate signal, data, or processing flows. Design 1.

[0025] An object detection system 100 is based on the Fig. 1 to 7 described. *** Configuration Description ***

[0026] Based on Fig. Section 1 describes a configuration of the object acquisition system 100.

[0027] The object detection system 100 is a system that uses a laser sensor 110 to detect a subject 101.

[0028] Subject 101 is an object to be grasped. In other words: Subject 101 is a target to be recognized.

[0029] The object detection system 100 includes a laser sensor 110, an attack detection device 120 and an object detection device 130.

[0030] The laser sensor 110 is specifically a LiDAR. The LiDAR is an infrared sensor. The attack detection device 120 and the object detection device 130 are computers.

[0031] Based on Fig. Section 2 describes a configuration of the laser sensor 110.

[0032] The laser sensor 110 includes three types of lasers (111, 112, 113).

[0033] A first main laser 111 and a second main laser 112 are measuring lasers and emit laser light with different wavelengths.

[0034] The first main laser 111 emits laser light of a first wavelength. Specifically, the first main laser 111 emits laser light of approximately 900 nanometers.

[0035] The second main laser 112 emits laser light of a second wavelength. Specifically, the second main laser 112 emits laser light of approximately 1550 nanometers.

[0036] A dummy laser 113 emits laser light of a third wavelength. The third wavelength is a wavelength between the first and second wavelengths. Specifically, the dummy laser 113 emits laser light of approximately 1000 nanometers.

[0037] The laser sensor 110 comprises two types of light receiving elements (114, 115).

[0038] A first light-receiving element 114 is a light-receiving element that is sensitive to light of the first wavelength. In particular, the first light-receiving element 114 is a light-receiving element that uses a silicon (Si) semiconductor.

[0039] A second light-receiving element 115 is a light-receiving element that is sensitive to light of the second wavelength. In particular, the second light-receiving element 115 is a light-receiving element that uses a compound semiconductor made of indium gallium arsenide (InGaAs).

[0040] The laser sensor 110 has a mechanism by which all three types of lasers (111, 112, 113) and the two types of light receiving elements (114, 115) can be rotated to perform a measurement in a large environmental area.

[0041] The laser sensor 110, for example, has a rotation mechanism to perform measurements in a 360-degree environment. The rotation mechanism rotates all three lasers and the two light-receiving elements by 360 degrees.

[0042] Based on Fig. Section 3 describes a configuration of the attack detection device 120.

[0043] The attack detection device 120 includes hardware referred to as the processing circuit 129.

[0044] The attack detection device 120 includes an element referred to as the attack detection unit 121.

[0045] The processing circuit 129 is hardware that implements the attack detection unit 121.

[0046] The processing circuit 129 can be special hardware or a processor that executes programs stored in main memory.

[0047] The dedicated hardware might be, for example, a single circuit, a compound circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0048] ASIC is an abbreviation for Application Specific Integrated Circuit.

[0049] FPGA is an abbreviation for Field Programmable Gate Array.

[0050] Based on Fig. Section 4 describes a configuration of the object detection device 130.

[0051] The object detection device 130 includes hardware referred to as the processing circuit 139.

[0052] The object detection device 130 includes an element referred to as object detection unit 131.

[0053] The processing circuit 139 is hardware that implements the object detection unit 131.

[0054] The processing circuit 139 can be special hardware or a processor that executes programs stored in main memory.

[0055] Fig. Figure 5 shows the relationships between the elements of the object acquisition system 100.

[0056] The three types of lasers (111, 112, 113) emit laser light. It should be noted that the two main types of lasers (111, 112) emit laser light alternately.

[0057] The two types of light receiving elements (114, 115) receive (detect) the laser light reflected from the subject 101 and output received light signals.

[0058] Receiving light means receiving light and converting the received light into an electrical signal.

[0059] Acquisition means treating an electrical signal as point cloud data. If the amount of light exceeds a certain threshold, the electrical signal is considered point cloud data. Electrical signals that are not considered point cloud data are discarded as unnecessary data.

[0060] A received light signal is an electrical signal obtained by receiving and capturing light and represents laser light.

[0061] The attack detection unit 121 receives received light signals, detects an attack by the attack device 109 and outputs received light signals that are not under attack.

[0062] The object detection unit 131 processes received light signals that are not attacked in order to detect the subject 101.

[0063] Attack device 109 is a device that performs a spoofing attack.

[0064] The attack device 109 captures the laser light emitted by the three types of lasers and emits laser light for interference. *** Description of a business ***

[0065] A process for operating the object acquisition system 100 corresponds to an object acquisition procedure.

[0066] Based on the Fig. 6 and Fig. Section 7 describes the object acquisition procedure.

[0067] Based on Fig. Section 6 describes the operation of the laser sensor 110 in the object detection method.

[0068] In step S101, the first main laser 111 and the second main laser 112 alternately emit laser light. Additionally, the dummy laser 113 continues to emit laser light.

[0069] The first main laser 111 emits laser light of the first wavelength. The laser light with the first wavelength is referred to as the first laser light.

[0070] The second main laser, 112, emits laser light of the second wavelength. This laser light with the second wavelength is referred to as the second laser light.

[0071] The dummy laser 113 emits laser light of the third wavelength. This laser light with the third wavelength is referred to as dummy laser light.

[0072] Each of the first laser light, the second laser light, and the dummy laser light is reflected upon hitting subject 101.

[0073] When the first laser light, the second laser light, or the third laser light is detected, the attacking device emits 109 laser light for interference. The laser light for interference is referred to as attack laser light.

[0074] In step S102, the first light receiving element 114 and the second light receiving element 115 receive laser light.

[0075] The first light-receiving element 114 detects the first laser light. If the wavelength of the attack laser light is close to the first wavelength, the first light-receiving element 114 detects both the first laser light and the attack laser light. The second laser light and the dummy laser light, however, are not detected by the first light-receiving element 114.

[0076] The second light-receiving element 115 detects the second laser light. If the wavelength of the attack laser light is close to the second wavelength, the second light-receiving element 115 detects both the second laser light and the attack laser light. The first laser light and the dummy laser light, however, are not detected by the second light-receiving element 115.

[0077] In step S103, the first light receiving element 114 and the second light receiving element 115 output received light signals.

[0078] The received light signal emitted by the first light receiving element 114 is referred to as the first received light signal.

[0079] The received light signal emitted by the second light receiving element 115 is referred to as the second received light signal.

[0080] Based on Fig. Section 7 describes the operation of the attack detection device 120 and the object detection device 130 in the object detection procedure.

[0081] In step S111, the attack detection unit 121 receives the received light signals from the first light receiving element 114 and the second light receiving element 115.

[0082] In step S112, the attack detection unit 121 determines a signal-to-noise ratio (S / N ratio) for each of the received light signals. The signal-to-noise ratio of the received light signal is determined as follows.

[0083] First, the attack detection unit 121 calculates the signal-to-noise ratio of the received light signal.

[0084] Then the attack detection unit 121 compares the signal-to-noise ratio with a threshold value.

[0085] If the S / N ratio is equal to or greater than the threshold, the attack detection unit 121 determines that the S / N ratio is good.

[0086] If the S / N ratio is below the threshold, the attack detection unit 121 determines that the S / N ratio is poor.

[0087] If the signal-to-noise ratio is good, the process proceeds to step S113.

[0088] If the signal-to-noise ratio is poor, the received light signal is treated as the dummy laser light signal. Therefore, the received light signal is eliminated as an unnecessary point cloud. That is, the received signal is eliminated as an electrical signal that is not converted into point cloud data. The process then terminates without any object acquisition.

[0089] In step S113, the attack detection unit 121 determines whether the first received light signal from the first light receiving element 114 and the second received light signal from the second light receiving element 115 were received simultaneously.

[0090] If the first and second received light signals are not received simultaneously, the process proceeds to step S114.

[0091] If the first and second received light signals are received simultaneously, one of the received light signals is considered an attack signal. Therefore, the received light signal is processed as a false reflection wave. This means that although the received light signal contains valid point cloud data, it is considered an attack signal, and the point cloud is therefore removed to prevent it from interfering with subsequent applications. Subsequent applications include, for example, processing by processing circuit 139. The process then terminates.

[0092] In step S114, the attack detection unit 121 determines whether both the first received light signal from the first light receiving element 114 and the second received light signal from the second light receiving element 115 have been received.

[0093] Once both the first and second light reception signals have been received, the attack detection unit 121 outputs both the first and second light reception signals. The process then continues with step S121.

[0094] If at least one of the first and second received light signals is not received, the received light signal is considered an attack signal. Therefore, the process ends without object detection.

[0095] In step S121, the object detection unit 131 receives the first received light signal and the second received light signal.

[0096] The object detection unit 131 then performs object detection using at least one of the first received light signals and the second received light signal. The result is that subject 101 is detected. The following processing is carried out during object detection.

[0097] The object detection unit 131 calculates a relative distance at a measurement time based on the flight time of laser light.

[0098] The relative distance is a distance from the laser sensor 110 to the subject 101 and is calculated by multiplying the speed of light by the flight time.

[0099] The flight time is the time from the emission of the laser light until its reception (detection). The flight time is measured, for example, by the number of clock cycles in an internal circuit.

[0100] The measurement time is the time at which the laser light is emitted or the time at which the laser light is received (detected).

[0101] The process ends after step S121. Steps S101 to S121 are repeated.*** Effects of embodiment 1 ***

[0102] Embodiment 1 enables countermeasures against deception attacks on sensors and advanced attacks, such as those that deceive sensor fusion.

[0103] Embodiment 1 makes it possible to significantly reduce an attacker's deception attack capability. The attacker can reconfigure a mechanism for eliminating signals with a poor signal-to-noise ratio. However, an attack that overcomes sensor fusion requires inserting a point cloud at a specific location and is difficult to implement when the attacker's freedom is restricted. Furthermore, since the attacker must add a new mechanism in addition to an existing attack mechanism, the attacker's attack costs are likely to increase. ***Summary of Implementation 1 ***

[0104] In the following description, the elements corresponding to the elements of embodiment 1 are placed in parentheses, and the reference numerals of the elements of embodiment 1 are given in the parentheses.

[0105] An infrared sensor (110) is characterized by its configuration and the detection signal processing.

[0106] A laser (111) of approximately 900 nm and a laser (112) of approximately 1550 nm alternately emit light. It should be noted that at the moment when laser light of approximately 900 nm is emitted, laser light of approximately 1550 nm is received but not processed as a point cloud. Likewise, at the moment when laser light of approximately 1550 nm is emitted, laser light of approximately 900 nm is received but not processed as a point cloud.

[0107] Laser light of approximately 1000 nm is emitted but treated as dummy light, which is not received as actual light. A silicon light receiving element (114) and an InGaAs light receiving element (115) respond to light with a wavelength of approximately 1000 nm, but the signal-to-noise ratio of this signal is poor. For this reason, the signal from light with a wavelength of approximately 1000 nm is eliminated during the point cloud processing phase.

[0108] In signal processing for attack detection, a distinction is made between genuine reflection waves and false reflection waves (signals from an attacker).

[0109] First, if light of the same wavelength arrives from the same position during each of the alternating measurements, the incoming light is considered a false reflection wave. This can prevent laser-emitting attacks using one wavelength of approximately 900 nm and another of approximately 1550 nm.

[0110] Next, if the light from laser (111) at approximately 900 nm and the light from laser (112) at approximately 1550 nm arrive simultaneously, the incoming light is considered a false reflection wave. This is because light at approximately 900 nm and light at approximately 1550 nm are emitted alternately, so normally only one of these two types of light is detected at any given time. Even if the attacker prepares a laser-emitting attack device (109) that supports both wavelengths, an attacker's light-receiving mechanism responds to dummy light at approximately 1000 nm, causing the laser-emitting attack device to emit laser light of both wavelengths. This allows an attack to be detected. This is because the attacker lacks a signal processing mechanism to eliminate signals with a poor signal-to-noise ratio.

[0111] Embodiment 1 is characterized in that dummy light is used for which the light receiving elements (114, 115) have a low measurement sensitivity.

[0112] By using measurable light as dummy light instead of using completely invisible light as dummy light, it is possible to provoke an attack by the attacker and eliminate false signals. *** Supplement to embodiment 1 ***

[0113] The received light signals emitted by the attack detection unit 121 are used for object detection and for mapping the environment based on a collection of point clouds.

[0114] To execute an attack that overcomes sensor fusion, simply emitting light is insufficient; it is necessary to emit light in such a way that a specific location and point clouds appear in a specific pattern. For example, the specific location might be behind an obstacle such as a car. The specific pattern could involve positioning the light so that the point clouds appear to form a cone. Directing light onto a moving object is difficult, and executing a sophisticated attack requires a high degree of freedom (few conditions for success). Reducing the attack's degrees of freedom therefore makes its implementation more difficult.

[0115] Embodiment 1 is an example of a preferred embodiment and is not intended to limit the technical scope of this disclosure. Embodiment 1 can be implemented partially or in combination with another embodiment.

[0116] The laser sensor 110 can be without the first main laser 111 or the second main laser 112.

[0117] The attack detection device 120 and the object detection device 130 can be implemented as separate devices.

[0118] The processes described in the flowcharts or similar documents can be modified as appropriate.

[0119] The order of step S112, step S113 and step S114 can be exchanged.

[0120] The “unit” of the individual elements of the attack detection device 120 and the object detection device 130 can be interpreted as “process”, “step”, “circuit” or “circuit”.

[0121] The programs can be recorded (stored) in a computer-readable format on a non-volatile recording medium, such as an optical disc or flash memory. Reference symbol list

[0122] 100: Object detection system; 101: Subject; 109: Attack device; 110: Laser sensor; 111: First main laser; 112: Second main laser; 113: Dummy laser; 114: First light receiving element; 115: Second light receiving element; 120: Attack detection device; 121: Attack detection unit; 129: Processing circuit; 130: Object detection device; 131: Object detection unit; 139: Processing circuit. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP H9-281397 A

[0017]

Claims

[1] Laser sensor, comprising: a main laser for emitting laser light of a specific wavelength; a dummy laser for emitting laser light with a wavelength different from the specific wavelength; and a light-receiving element that is sensitive to light of a specific wavelength. [2] Laser sensor according to claim 1, comprising: a first main laser, which is the main laser for emitting laser light of a first wavelength; a second main laser, which is the main laser for emitting laser light of a second wavelength; the dummy laser to emit laser light of a third wavelength; a first light-receiving element, which is the light-receiving element sensitive to light of the first wavelength; and a second light-receiving element, which is the light-receiving element sensitive to light of the second wavelength. [3] Laser sensor according to claim 2, wherein the first main laser and the second main laser alternately emit the laser light. [4] Laser sensor according to claim 2 or claim 3, wherein the third wavelength is a wavelength between the first wavelength and the second wavelength. [5] Laser sensor according to any one of claims 2 to 4, wherein the first wavelength is about 900 nanometers, wherein the second wavelength is about 1550 nanometers, and wherein the third wavelength is about 1000 nanometers. [6] Object detection system, comprehensive: a main laser for emitting laser light of a specific wavelength; a dummy laser for emitting laser light with a wavelength different from the specific wavelength; a light receiving element that is sensitive to light of a specific wavelength, wherein the light receiving element detects laser light and outputs a received light signal that is a signal of the detected laser light; an attack detection unit for determining the signal-to-noise ratio of the emitted received light signal; and an object detection unit for performing object detection using the received light signal, whose signal-to-noise ratio is determined to be good. [7] Object acquisition system, including: a first main laser for emitting laser light of a first wavelength and a second main laser for emitting laser light of a second wavelength, wherein the first main laser and the second main laser alternately emit the laser light; a dummy laser for emitting laser light of a third wavelength; a first light receiving element sensitive to light of the first wavelength, wherein the first light receiving element detects laser light and outputs a first received light signal which is a signal of the detected laser light; a second light receiving element sensitive to light of the second wavelength, wherein the second light receiving element detects laser light and outputs a second received light signal which is a signal of the detected laser light; an attack detection unit for receiving the first emitted receive light signal and the second emitted receive light signal, determining a signal-to-noise ratio of each of the first received receive light signal and the second received receive light signal, and determining whether the first receive light signal and the second receive light signal were received simultaneously; and an object detection unit for performing object detection when it is not determined that the first received light signal and the second received light signal were received simultaneously, wherein the object detection is performed using at least one of the first received light signal, whose signal-to-noise ratio is determined to be good, and the second received light signal, whose signal-to-noise ratio is determined to be good. [8] Object detection methods, comprehensive: Emitting laser light of a specific wavelength; Emitting laser light with a wavelength different from the specific wavelength; Exhibiting sensitivity to light of a specific wavelength, detecting laser light and outputting a received light signal that is a signal of the detected laser light; Determining the signal-to-noise ratio of the output received light signal; and Performing object detection using the received light signal, whose signal-to-noise ratio is determined to be good. [9] Object acquisition methods, comprehensive: alternately emitting laser light of a first wavelength and laser light of a second wavelength; Emitting laser light of a third wavelength; Exhibiting sensitivity to light of the first wavelength, detecting laser light and outputting a first received light signal, which is a signal of the detected laser light; Exhibiting sensitivity to light of the second wavelength, detecting laser light and outputting a second received light signal that is a signal of the detected laser light; Receiving the first emitted received light signal and the second emitted received light signal, determining a signal-to-noise ratio of each of the first received received light signal and the second received received light signal, and determining whether the first received light signal and the second received light signal were received simultaneously; and Performing object detection when it is not determined that the first received light signal and the second received light signal were received simultaneously, wherein the object detection is performed using at least one of the first received light signal, whose signal-to-noise ratio is determined to be good, and the second received light signal, whose signal-to-noise ratio is determined to be good.

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