Simulation device

Abstract

A simulation device (1) simulates, by means of rays, a path of radio waves when the radio waves are emitted from a radar R. In the device (1), when rays are emitted from the radar R and collide with an object, the reception power of radio waves at the collision position is calculated in accordance with attenuation of the radio waves occurring in a normal path from the radar R to the collision position with the object. The reception power of the radio waves on the normal path corresponds to the reception power of the radio waves on the returning route, and, since the radio waves travel in the reverse direction on the same path, the degree of attenuation midway on path is the same. Therefore, the reception power of the radio waves on the returning path is obtained on the basis of the reception power of the radio waves on the normal route.

Description

Simulation device Cross-reference to related applications

[0001] This international application claims the benefit of Japanese Patent Application No. 2024-232484, filed with the Japan Patent Office on December 27, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to the technology of simulating in-vehicle sensors and the like.

[0003] As a device (i.e., simulator) for performing virtual simulation of in-vehicle sensors such as radar, it is known to include a processing block that emits radio waves, ultrasonic waves, etc. into the outside world and performs propagation calculations to reproduce the reflected waves, and a processing block that inputs the reflected waves and calculates the output as a sensor.

[0004] In the propagation calculation, a 3D shape that reproduces the external environment is input, and the power reflected from these shapes to the sensor is calculated. In this propagation calculation, mainly the ray tracing method is used, which is a method of calculating by replacing radio waves, ultrasonic waves, etc. emitted from the sensor with light rays flying in all directions (see, for example, Patent Document 1).

[0005] As sensors, sensors such as radar, ultrasonic sensors (i.e., sonars), and LiDAR are known.

[0006] U.S. Patent Application Publication No. 2023 / 0099845

[0007] The following problems have been found with the above-mentioned conventional technology.

[0008] For example, since radar observes the time difference, power, and the speed of the target of radio wave reflection, accurate distance calculation by ray tracing is required. Also, it reflects in various directions, resulting in various reflections and a wide distance range, so the calculation load is high. That is, simulating all reflection patterns requires a processing capacity at an unrealistic level. Furthermore, since the processing of the sensor may change depending on whether there is reflection or not, there is a desire to reproduce this phenomenon in the simulation.

[0009] Furthermore, LiDAR requires accurate distance calculations using ray tracing to observe the time difference and power of laser light reflection. Similarly, sonar requires accurate distance calculations using ray tracing to observe the time difference and power of ultrasonic wave reflection.

[0010] Of these, radar, for example, has a particularly high level of demand for simulation-based reproduction, and simulations using ray tracing are not easy.

[0011] Conventional ray tracing techniques can reproduce some multipath paths that pass through road surfaces, but they cannot handle other paths. In other words, it is desirable for a simulator to be able to calculate multipath paths for general-purpose objects regardless of the object type, but no solution has been disclosed.

[0012] One aspect of this disclosure is the desire to provide a highly versatile and computationally intensive technology for simulation devices.

[0013] (1) One embodiment of the present disclosure relates to a simulation device that simulates the path of a sensor wave when a sensor wave is emitted from a sensor, using a pseudo-ray that simulates the sensor wave. The simulation device comprises a normal direction processing unit and a reverse direction processing unit.

[0014] The normal direction processing unit is configured to determine the power corresponding to the energy of the sensor wave at the collision point when the pseudo-ray is emitted from the sensor and collides with an object, in accordance with the attenuation of the energy of the sensor wave generated in the normal path from the sensor to the collision point of the object.

[0015] The reverse direction processing unit is configured to determine the reverse path when the pseudo-ray is reflected once or more times before reaching the collision position of the object, by switching the incident direction of the sensor wave at the collision position of the pseudo-ray to a direction that returns to the sensor, and to determine the power corresponding to the energy of the sensor wave in the reverse path.

[0016] This configuration provides the simulation device with the advantages of high versatility and low computational load, as described in this disclosure.

[0017] This disclosure makes it possible to determine the power corresponding to the energy of the sensor wave at the collision site in accordance with the attenuation of the energy of the sensor wave corresponding to the ray in the normal path. Furthermore, it is possible to determine the power corresponding to the energy of the sensor wave in the reverse path of the ray. Of these, the power corresponding to the energy of the sensor wave in the reverse path can be determined from the power corresponding to the energy of the sensor wave in the normal path, thus reducing the computational load in the simulation. In other words, the processing of one ray can effectively be used to process two rays.

[0018] Furthermore, this disclosure has the advantage of being highly versatile because it can perform calculations without being limited by the state of the object to which the pseudo-ray is irradiated (for example, the type of object that the pseudo-ray collides with or the position of the object).

[0019] (2) Another embodiment of the present disclosure relates to a simulation apparatus that simulates the path of a sensor wave when a sensor wave is emitted from a sensor, using a pseudo-ray that simulates the sensor wave. The simulation apparatus comprises a normal direction processing unit and a path addition processing unit.

[0020] The normal direction processing unit is configured to determine the power corresponding to the energy of the sensor wave incident on the sensor when the pseudo-ray is emitted from the sensor and reflected by the object and incident on the sensor, according to the attenuation of the energy of the sensor wave generated in the normal path of the pseudo-ray from the sensor to the sensor.

[0021] The path addition processing unit is configured to add an inverted path, which is the reverse of the transmission path, which is the normal path of the pseudo-ray from emission to incidence.

[0022] This configuration provides the simulation device with the advantages of high versatility and low computational load, as described in this disclosure.

[0023] This disclosure makes it possible to determine the power corresponding to the energy of the sensor wave when a ray is incident on a sensor, based on the attenuation of the energy of the sensor wave corresponding to the ray in the normal path. Furthermore, an inverted path can be added by reversing the transmission path. Therefore, the power corresponding to the energy of the sensor wave in this inverted path can be determined. Of these, the power corresponding to the energy of the sensor wave in the inverted path can be determined from the power corresponding to the energy of the sensor wave in the transmission path, thus reducing the computational load in the simulation. In other words, the processing of one ray can effectively be used to process two rays.

[0024] Furthermore, this disclosure has the advantage of being highly versatile because it can perform calculations without being limited by the state of the object to which the pseudo-ray is irradiated (for example, the type of object that the pseudo-ray collides with or the position of the object).

[0025] Examples of sensor waves include radio waves (i.e., radar waves), ultrasound, and laser light.

[0026] This is a block diagram showing the configuration of the simulation device of the first embodiment. This is an explanatory diagram illustrating a basic ray tracing method. This is a flowchart showing the processing in basic ray tracing. This is a plan view explanatory diagram showing the characteristic path of a ray. This is a plan view explanatory diagram showing an example of the reflection state of a ray emitted from a radar. Figure 6A is a plan view explanatory diagram showing the reflection state of a ray in Example 1, and Figure 6B is a flowchart showing the processing per ray in Example 1. Figure 7A is a plan view explanatory diagram showing the reflection state of a ray in Example 2, and Figure 7B is a flowchart showing the processing per ray in Example 2. This is a flowchart showing the processing per ray in Example 3. Figure 9A is a flowchart showing the process of calculating the power to change the path from the collision position to the reverse path in Example 3, and Figure 9B is a flowchart showing the process of creating data with the transmission direction and reception direction of the ray reversed in Example 3. Figure 10A is a plan view explanatory diagram showing the case where the reflection direction and the direction of the reverse path are close in Example 3, and Figure 10B is a plan view explanatory diagram showing the case where the reflection direction and the reception direction are close in Example 3. This is an explanatory diagram showing the manually operable operation section on the display screen of the display device. This is an explanatory diagram showing the main parts of the simulation device of the second embodiment. This is a flowchart showing the processing per ray in the second embodiment. This is a flowchart showing the overall ray tracing process in the second embodiment.

[0027] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0028] [1. First Embodiment] [1-1. Overall Configuration] As shown in Figure 1, the simulation device 1 of this first embodiment is a simulator that simulates the operation of sensors (e.g., active sensors) mounted on vehicles such as automobiles. Here, we will explain using a simulation device 1 that simulates the operation of radar (i.e., a radar simulator) as an example.

[0029] The simulation apparatus 1 of this first embodiment is an electronic processing device that uses well-known ray tracing technology, and comprises a display unit 3, an operation input unit 5, a data storage unit 7, a data input / output unit 9, and a control unit 11.

[0030] The display unit 3 comprises a display device 13 and a display control unit 15 that controls the operation of the display device 13, and displays various images and the like on the display screen of the display device 13. For example, it displays simulated rays and various operation screens, which will be described later. The display unit 3 also has so-called GUI functionality. GUI stands for Graphical User Interface.

[0031] The operation input unit 5 outputs input operation information to identify the input operations performed by the user via a keyboard and mouse (not shown). Alternatively, the display device 13 may be equipped with touch panel functionality and serve as the operation input unit 5.

[0032] The data storage unit 7 is a memory device for storing various types of data.

[0033] The data input / output unit 9 performs data input and output with external devices connected via wired or wireless connection.

[0034] The control unit 11 is primarily composed of a microcomputer equipped with a CPU 21, ROM 23, RAM 25, etc. The various functions of the microcomputer are realized by the CPU 21 executing a program stored in a non-transitional physical recording medium. In this example, the ROM 23 corresponds to the non-transitional physical recording medium that stores the program. Furthermore, the execution of this program executes a method corresponding to the program. Note that some or all of the functions executed by the CPU 21 may be configured in hardware using one or more ICs, etc. Also, the number of microcomputers constituting the control unit 11 may be one or more.

[0035] ROM23 stores the simulation program. The simulation program may be pre-installed on the simulation device 1, or it may be installed via a recording medium or network. Examples of recording media include optical discs, magnetic discs, and semiconductor memory.

[0036] In this example, a CPU 21 is used to represent the configuration for the calculations performed by the control unit 11, but a GPU capable of parallel execution of calculations such as pseudo-ray calculations may also be used. Furthermore, both a CPU 21 and a GPU may be provided. In that case, both the CPU 21 and the GPU may be equipped with ROM and RAM, respectively. GPU stands for Graphics Processing Unit.

[0037] [1-2. Basic Configuration of Ray Tracing] <Outline of Ray Tracing> In this first embodiment, the ray tracing method (i.e., ray tracing method) is used to simulate the path of radio waves, power, etc., so first, the basic configuration will be explained.

[0038] As is well known, ray tracing uses a geometric optics approximation to treat radio waves as light, that is, it uses pseudo-rays (hereinafter referred to as "rays") that mimic radio waves to simulate the propagation path of radio waves and to determine the received power of the radio waves.

[0039] In particular, in the case of radar, the simulation device 1 emits rays from the radar that simulate radar waves, and estimates the paths of reflected waves when these rays hit walls, other vehicles, etc. Furthermore, it calculates the received power of the radio waves received by the radar (i.e., the radio waves corresponding to the rays) when the reflected waves, which are formed when the rays emitted from the radar hit walls, other vehicles, etc., are incident on the radar. In particular, since the power of radio waves is attenuated along the propagation path and at reflection points, the power of the radio waves received by the radar can be calculated by taking this attenuated power into consideration.

[0040] That is, in the simulation device 1, the ray emitted from the radar can hit a 3D-shaped object arranged in a three-dimensional space (i.e., 3D space), repeat reflections, and simulate the ray returning from the reflection point to the radar. Therefore, the power of the radio wave (i.e., the received power) corresponding to the ray from the time it is emitted from the radar until it returns to the radar can be calculated.

[0041] Hereinafter, the basic procedure of ray tracing will be specifically described with reference to the configuration shown in FIG. 2.

[0042] Here, consider a case where a plurality of rays simulated as radar waves are emitted from the radar R of a certain vehicle (for example, the host vehicle) C1 in a predetermined direction (for example, the front of the host vehicle C1).

[0043] In FIG. 2, the direction and path of the ray are represented by solid lines and broken lines with arrows. Also, the reflection point, which is the collision point of the ray, is indicated by a round mark at the bent portion of the ray. Here, the transmission direction is the direction in which the ray is emitted from the radar R (i.e., the projection direction), and the reception direction is the direction in which the ray enters the radar R.

[0044] For example, when a ray is emitted in a certain transmission direction, the ray is reflected at the reflection point P1 on the ground and changes its direction, and then is reflected at the reflection point P2 of the vehicle in front (for example, another vehicle) C2. The ray reflected at the reflection point P2 is reflected in a predetermined direction according to the direction of the surface (i.e., the reflection surface) where the reflection point P2 collides. For example, it may be reflected in the direction of entering the radar R or in the reflection direction shown in FIG. 2.

[0045] <Ray-by-Ray Processing> Next, the ray-by-ray processing performed by the simulation device 1 will be described.

[0046] As shown in the flowchart of FIG. 3, first, in step (hereinafter, 100), the initial direction of emitting the ray is determined.

[0047] In the subsequent S110, it is determined whether the ray has been reflected a predetermined number of times (that is, whether the reflection a predetermined number of times has been repeated). If an affirmative determination is made here, this process is terminated once, while if a negative determination is made, the process proceeds to S120. Note that the number of reflections is defined in consideration of suppressing the calculation load and the accuracy of the calculation result.

[0048] In S120, the ray is emitted in the determined direction (that is, the ray is projected in a predetermined direction).

[0049] In the subsequent S130, it is determined whether the emitted ray collides. If an affirmative determination is made here, the process proceeds to S140, while if a negative determination is made, this process is terminated once.

[0050] In S140, the power of the radio wave (for example, received power) corresponding to the ray at the collision position (for example, the position of the reflection point P1 in FIG. 2) is calculated.

[0051] For example, the power of the radio wave (that is, radar wave) attenuates according to the distance of the path from the radar R to the collision position (that is, propagation distance), and the power of the radio wave also attenuates depending on the material of the collision surface at the collision position. That is, since the power of the radio wave emitted from the radar R attenuates according to the path and the collision surface, the received power of the radio wave at the collision position is calculated in consideration of the attenuation amount of the power of the radio wave. That is, the received power of the radio wave at the collision position is the power of the radio wave at the time of emission reduced by the attenuation amount.

[0052] In the subsequent S150, the received power of the radio wave calculated in S140 is written into an output memory (for example, RAM 25) used when outputting data.

[0053] In the subsequent S160, the reflection direction of the ray reflected at the collision position (for example, P1 in FIG. 2) is determined, and the process returns to the above S110. For example, when the ray specularly reflects on the ground, that direction is taken as the reflection direction.

[0054] <Characteristic Ray Path> Next, based on FIG. 4, the characteristic ray path will be described. Note that the direction of the ray is indicated by an arrow with a solid line.

[0055] Figure 4A shows the path (i.e., the direct wave path) of a ray emitted from the radar R of vehicle C1, reflected by another vehicle C2 in front of it, and returning directly to the radar R of vehicle C1.

[0056] Figure 4B shows the path of a ray emitted from the radar R of vehicle C1, which strikes the side of the adjacent truck C3, reflects off another vehicle C2, and returns to the radar R of vehicle C1. Such polygonal (e.g., triangular) ray paths may be referred to as polygonal wave paths below.

[0057] Figure 4C shows a path that is the reverse of the polygonal wave path shown in Figure 4B. Specifically, it shows the path (i.e., the reverse path of the polygonal wave) in which a ray emitted from the radar R of vehicle C1 hits another vehicle C2 in front and is reflected, and the reflected wave hits the side of truck C3 to the side and is reflected back to the radar R of vehicle C1.

[0058] Figure 4D shows an example of the path through which reflected objects become visible, the so-called ghost wave path. For example, consider a path in which a ray emitted from the radar R of vehicle C1 hits the side of truck C3 to the side and is reflected, that reflected wave is reflected by another vehicle C2, and then that reflected wave hits the side of truck C3 again and is reflected back to the radar R of vehicle C1.

[0059] In this case, the reflected wave from the other vehicle C2 returns from the truck C3 to the own vehicle C1. Therefore, the radar R sees the reflected wave from the other vehicle C2 returning via the dashed line path K2, which is an extension of the ray path K1 returning from the truck C3 to the own vehicle C1. Consequently, in this case, the other vehicle C2g shown by the dashed line in Figure 4D becomes a ghost that does not actually exist.

[0060] <Challenges in calculations when rays reflect> Next, we will explain the challenges in calculations when rays reflect, based on Figure 5.

[0061] In ray tracing, the path of a ray is followed, and the direction of the ray is updated to the direction of reflection each time a reflection occurs. However, processes that add a ray when a reflection occurs (for example, adding a ray at reflection point P3) are usually not performed because the computational complexity would explode.

[0062] For example, ray tracing often determines the direction of ray reflection based on the shape of the object. Normally, rays are reflected in a direction where the angle of incidence to the surface is equal to the angle of reflection, but depending on the shape of the object, a path like the one shown in Figure 4 may not be generated.

[0063] In reality, since radio waves are waves, they reflect in directions other than the angle of incidence and the angle of reflection. However, reflecting radio waves in multiple directions is computationally intensive and undesirable.

[0064] For example, if two rays are generated for each reflection, then after five reflections, the number of rays generated would be 2 to the power of 5. Moreover, in general, ray tracing takes time for collision detection, which calculates whether a ray collides with an object. Therefore, simply calculating all possible paths would increase the processing load, leading to increased memory usage and computation time.

[0065] Therefore, as will be described later, it is preferable to devise ways to reduce the processing burden of the calculations.

[0066] [1-3. Example 1] <Processing related to ghost waves> Next, the simulation using ray tracing in Example 1 will be described based on Figure 6. Here, the processing related to ghost waves will be described.

[0067] In this embodiment 1, as shown in Figure 6B, the initial direction of the ray is determined in S200, similar to the basic process shown in Figure 3.

[0068] In the following step S210, it is determined whether the number of reflections of the ray has reached a predetermined number of reflections. If the determination is positive, this process is terminated; however, if the determination is negative, the process proceeds to S220.

[0069] In S220, the ray is fired in a predetermined direction.

[0070] In step 230, it is determined whether the ray collides and reflects. If the result is positive, the process proceeds to S240; however, if the result is negative, this process is temporarily terminated.

[0071] In S240, the amount of attenuation of the radio wave power is calculated from the material of the object the ray collides with and the propagation distance of the ray, and stored in memory as ray information. In addition, information such as the incident direction and reflection direction of the ray may also be stored as ray information. The propagation distance of the ray can be the distance from the ray emission position of radar R (i.e., the starting point of ray transmission) to the point where it hits the object (i.e., the destination of the ray), or the distance from the point where the ray is reflected by the object (i.e., the starting point of ray transmission) to the point where it hits the next object (i.e., the destination of the ray).

[0072] Here, similar to the processing in S140 in Figure 3, the received power of the radio waves corresponding to the ray at the collision site can be calculated. In other words, since the power of the radio waves emitted from radar R is attenuated according to the path and collision surface, the received power of the radio waves at the collision site can be calculated by subtracting the amount of attenuation from the power of the radio waves at the time of emission.

[0073] Furthermore, since the reflection of the ray is repeated a predetermined number of times, the amount of attenuation of the radio wave power can be calculated for each collision location (i.e., depending on the material of the collision location and the propagation distance to the collision). In other words, the received power of the radio wave gradually decreases each time the ray travels along each path and makes repeated collisions. Therefore, using the amount of attenuation of the radio wave power at each collision location, the received power of the radio wave at each collision location and the received power at radar R can be calculated sequentially.

[0074] The processes in S250 and S260 are performed when certain conditions are met, and will be explained later.

[0075] In S270, for example, the received power of the radio waves at the collision position (i.e., the reflection point), and the power calculated in S250 and S260 are written to the output memory.

[0076] In the subsequent S280, the direction of the reflected ray is determined, and the process returns to S210.

[0077] Now, let's explain the process in S250.

[0078] This process is performed, for example, after the process of a ray entering the radar R of vehicle C1 from the collision point (reflection point P5) of another vehicle C2 is completed.

[0079] Specifically, as shown in Figure 6A, this process is performed when a ray is incident directly on the radar R of the own vehicle C1 from the collision point (reflection point P5) of another vehicle C2.

[0080] Here, we calculate the power returned directly from the collision site to radar R. That is, we calculate the received power of the radio wave when the ray is incident on radar R from the collision site via path K5 (i.e., the path shown by the thick arrow L1). In Figure 6, the part related to this process is indicated by (L1).

[0081] Next, the processing in S260 will be explained.

[0082] This process is performed, for example, after the processing of the ray from radar R to the collision point (reflection point P5) is complete.

[0083] This process calculates the received power of the radio waves (i.e., the power returning from the collision point in the reverse direction) when the ray's path is changed from the collision point (reflection point P5) to the reverse path direction. In other words, as shown in Figure 6A, this process concerns the reverse path of the ray, i.e., the path that includes the radar R of vehicle C1, path K3, reflection point P4 of truck C3, and path K4 (i.e., the process concerning L2).

[0084] Specifically, we calculate the power of the radio waves when the ray's path is changed from the collision point (reflection point P5) of another vehicle C2 to a reverse path such as path K4, reflection point P4, and path K3. The thick line L2 in Figure 6A shows the ray traveling in the reverse direction from the collision point.

[0085] To calculate the power of the radio waves in the reverse direction, the power of the radio waves corresponding to the ray emitted from the vehicle C1, reflected by track C3, and reaching the collision point (reflection point P5) is determined in advance. In other words, this process is performed after the power of the radio waves corresponding to the ray that reaches the collision point via paths K3 and K4 from radar R has been calculated.

[0086] The power attenuation (i.e., radio wave attenuation) of the radio waves corresponding to the ray along its normal path from radar R to the collision site via paths K3 and K4 is equal to the radio wave attenuation of the ray along its reverse path. Therefore, if the radio wave attenuation along the ray's normal path is known, the radio wave attenuation along the ray's reverse path can be determined.

[0087] However, if a ray collides at the collision point (reflection point P5), attenuation of the radio wave occurs at that collision point. Therefore, it is necessary to consider this attenuation when determining the attenuation of the radio wave in the reverse path of the ray. In other words, the power of the radio wave reflected from the collision point in the direction of path K4 (i.e., reflected and projected in a predetermined direction) is attenuated by the material at the collision point, etc., so this attenuated power of the radio wave becomes the power of the radio wave projected from the collision point to path K4.

[0088] Therefore, in the reverse path, the power of the radio waves incident on radar R from the collision point can be calculated by subtracting the previously calculated attenuations of the radio waves in path K4, the attenuation of the radio waves at the reflection point P4, and the attenuation of the radio waves in path K3 from the power of the radio waves projected from the collision point to path K4 (i.e., the power attenuated at the collision point).

[0089] In this embodiment 1, the path extending to the upper left of path K3 in Figure 6A becomes the path of the ghost wave, so that the non-existent ghost vehicle C2g is recognized in the direction of the extension of path K3.

[0090] As described above, in this embodiment 1, the power of the radio waves along the normal path to the ray collision site can be determined. Furthermore, based on the power of the radio waves along the normal path, the power of the radio waves along the reverse path (i.e., the reverse path) can be determined by retracing the normal path from the ray collision site.

[0091] [1-4. Example 2] <Processing related to polygonal waves> Next, the simulation using ray tracing in Example 2 will be described based on Figure 7. Here, processing related to polygonal waves will be described.

[0092] In this embodiment 2, as shown in Figure 7B, the initial direction of the ray is first determined in S300, similar to the process shown in Figure 6B.

[0093] In the following step S310, it is determined whether the number of reflections of the ray has reached a predetermined number of reflections. If the determination is positive, this process is terminated; however, if the determination is negative, the process proceeds to S320.

[0094] In S320, the ray is fired in a predetermined direction.

[0095] In step 330, it is determined whether the ray collides and reflects. If the result is positive, the process proceeds to S340; however, if the result is negative, this process is temporarily terminated.

[0096] In S340, the same process as in S240 of Embodiment 1 is performed.

[0097] Specifically, the attenuation of the radio wave power is calculated from the material of the object the ray collides with and the propagation distance of the ray, and this is stored in memory as ray information. Here, similar to the processing in S140 in Figure 3, the received power of the radio wave corresponding to the ray at the collision site can be calculated.

[0098] Furthermore, since the ray reflection is repeated a predetermined number of times, the received power of the radio waves at each collision location can be sequentially determined using the attenuation of the radio wave power at each collision location. In addition, the received power of the radio waves returning to radar R from the last collision location can be calculated.

[0099] The processes in S350 and S360 are performed when predetermined conditions are met, similar to those in Example 1, and will be explained later.

[0100] In S370, the received power of the radio waves at the collision position (i.e., the reflection point), and the power calculated in S350 and S360 are written to the output memory.

[0101] In the subsequent S380, the direction of the reflected ray is determined, and the process returns to S310.

[0102] Now, let's explain the process in S350.

[0103] This process is the same as the process in S250 of Example 1 and is performed when a ray is directly incident on the radar R of the own vehicle C1 from the collision position (reflection point P5) of the other vehicle C2. Specifically, it calculates the power that is returned directly to the radar R from the collision position.

[0104] Next, we will explain the processing in S360 (i.e., the process of creating data with the transmission and reception directions reversed).

[0105] This process is performed after the ray has completed the process from being emitted from radar R, to being reflected at each collision location (reflection points P4 and P5 in Figure 7A), and returning to radar R.

[0106] This process, as shown in Figure 7A, is a process for the reverse path (i.e., the inverted path) of the ray, as opposed to the process for the normal path (i.e., the process for the clockwise path L3 in Figure 7A).

[0107] Here, Ray's normal clockwise path is the path from the radar R of vehicle C1, through path K3, the reflection point P4 of truck C3, path K4, the reflection point P5 of other vehicle C2, and path K5, to reach radar R.

[0108] On the other hand, Ray's counter-clockwise path (i.e., the reverse path) is the path that returns to radar R from the radar R of vehicle C1, via path K5, reflection point P5 of other vehicle C2, path K4, reflection point P4 of truck C3, and path K3.

[0109] As described above, in this embodiment 2, the power of the radio waves incident on radar R in the normal path of the ray can be determined. Furthermore, based on the power of the radio waves in the normal path, the power of the radio waves in the inverted path of the ray can be determined.

[0110] In other words, since the attenuation of radio waves at each path and reflection point of the ray can be determined, the received power of radio waves incident on radar R via the normal path can be determined from the normal path of the ray. Furthermore, since the attenuation of radio waves in the normal path and the attenuation of radio waves in the inverted path are the same, the received power of radio waves incident on radar R via the normal path can be used as the received power of radio waves returning to radar R in the inverted path. That is, using the information of the ray in the normal path (i.e., using the information when the ray is inverted), the received power of radio waves incident on radar R in the inverted path of the ray can be determined.

[0111] [1-4. Example 3] Next, the simulation of Example 3 will be described based on Figures 8 and 9. Here, the processing is performed by combining the processes of Example 1 and Example 2, so similar content will be explained briefly.

[0112] As shown in Figure 8, in this embodiment 3, in S400, the initial direction of the ray is determined in the same way as in S300 of embodiment 2.

[0113] In the subsequent S410, similar to S310, it is determined whether the number of ray reflections has reached a predetermined number of reflections. If the determination is positive, this process is terminated; however, if the determination is negative, the process proceeds to S320.

[0114] In S420, a ray is fired in a predetermined direction, similar to S320.

[0115] In the subsequent step 430, similar to step S330, it is determined whether the ray collides and reflects. If the result is positive, the process proceeds to step S440; however, if the result is negative, this process is temporarily terminated.

[0116] In S440, similar to S340, the amount of attenuation of the radio wave power is calculated from the material of the object the ray collides with and the propagation distance of the ray, and stored in memory as ray information.

[0117] Furthermore, since the ray reflection is repeated a predetermined number of times, the received power of the radio waves at each collision location can be sequentially determined using the attenuation of the radio wave power at each collision location. In addition, the received power of the radio waves returning to radar R from the last collision location (reflection point P5) can be calculated.

[0118] In S450, similar to S350, the power returned directly to radar R from the collision point is calculated. This process is performed when a ray is directly incident on radar R of vehicle C1 from the collision point (reflection point P5) of another vehicle C2. Specifically, the power returned directly to radar R from the collision point is calculated.

[0119] In S460, similar to S260 in Embodiment 1, the power of the radio waves when the ray's path is changed from the collision position to the reverse path direction (i.e., the power returning from the collision position to the reverse path direction) is calculated. In other words, as shown in Figure 6A, this process calculates the power of the radio waves when the ray's path is changed to the reverse of its normal path, that is, when the ray returns to radar R from the collision position of other vehicle C2 (reflection point P5) via path K4, reflection point P4, and path K3.

[0120] In S470, similar to S360 in Embodiment 2, a process is performed to create data with the transmission and reception directions reversed. Here, as described above, the power of the radio waves incident on the radar R can be calculated for the reversed path (see L4 in Figure 7A), which is obtained by reversing the clockwise path of the normal path (see L3 in Figure 7A) to a counterclockwise direction.

[0121] In S490, the received power of the radio waves at the collision position (i.e., the reflection point) and the power calculated in S450 to S470 are written to the output memory.

[0122] In the following step S495, the direction of the reflected ray is determined, and the process returns to step S410.

[0123] <Example of processing in S460> Next, based on Figures 9A and 10A, an example of the processing performed in S460, that is, the processing to calculate the power of radio waves when the ray path is changed to return from the collision position in the reverse direction, will be explained.

[0124] First, let me explain the general outline of this process.

[0125] When a ray collides with an object, the amount of attenuation due to the material and distance from the time of transmission from radar R to the time of collision is stored in memory as ray information.

[0126] For the power in the reverse path, the power is calculated for the direction of the ray's incidence on the collision surface and its return, and the attenuation due to the material and distance until it is received by radar R is reflected in the ray information stored in memory.

[0127] If the normal reflection direction (for example, the direction when specular reflection occurs as usual at reflection point P6 on the collision surface in Figure 10A) and the direction of the reverse path coincide, the radar R will receive twice the power. Therefore, as shown in Figure 10A, if these directions are close, for example, the attenuation amount of the ray information stored in memory is increased to reduce the power in the normal reflection direction.

[0128] In addition to reducing the power of the radio waves in the normal reflection direction, the power of the radio waves in the reverse path direction may also be reduced, or the power of both radio waves may be reduced. Furthermore, the power of the radio waves in the normal reflection direction may be eliminated, or the power of the radio waves in the reverse path direction may be eliminated.

[0129] Next, we will explain the specific steps of this process.

[0130] As shown in Figure 9A, in S500, the power of the radio wave corresponding to the case where the ray is emitted in the reverse direction is calculated from the shape of the ray path and the incident direction at the collision position (see Figure 6A).

[0131] In S510, the attenuation of radio waves up to the point of collision is reflected, and the attenuation continues until it is received by radar R.

[0132] In S520, as shown in Figure 10A, it is determined whether the normal reflection direction and the direction of the reverse path are close, that is, whether the angle between the normal reflection direction and the direction of the reverse path is less than or equal to a predetermined value. If the determination is positive, the process proceeds to S530; on the other hand, if the determination is negative, this process is terminated.

[0133] To determine the angle between the normal reflection direction and the direction of the reverse path, the dot product of the direction vector of the reflection direction and the direction vector of the reverse direction may be used. In other words, the determination may be made by checking whether the dot product is less than or equal to a predetermined value. The absolute value of both direction vectors is set to 1.

[0134] In S530, the attenuation is adjusted according to the degree of agreement between the normal reflection direction and the direction of the reverse path, and the process is terminated. For example, if the degree of agreement between the two directions is large (i.e., the angle between the two directions is small), the power of the radio waves in at least one direction is reduced, as described above.

[0135] <Example of processing in S470> Next, based on Figures 9B and 10B, an example of the processing performed in S470, that is, the processing that creates data with the transmission direction and reception direction reversed, will be explained.

[0136] First, let me explain the general outline of this process.

[0137] When generating polygonal waves, after calculating the power of the radio waves along the normal path for a given ray, the information for that ray is duplicated and the transmission and reception directions are reversed.

[0138] Furthermore, another ray may calculate a similar path, and if they coincide, twice the radio wave power will be received. While the data of another ray cannot be referenced in general ray tracing, it can be generated in a normal path using the rule that the angle of incidence and the angle of reflection are equal. Therefore, if the direction of reflection and the direction of reception to radar R are close (see, for example, Figure 10B), it may reduce its own duplicated power (i.e., the power of the radio wave in the direction of reception).

[0139] In addition to reducing the power of the radio waves in the receiving direction, the power of the radio waves in the normal reflection direction may also be reduced, or the power of both radio waves may be reduced. Furthermore, the power of the radio waves in the receiving direction may be eliminated, or the power of the radio waves in the normal reflection direction may be eliminated.

[0140] Next, we will explain the specific steps of this process.

[0141] As shown in Figure 9B, in S600, the ray data is duplicated and the transmission direction and reception direction are reversed. As mentioned above, the received power of the radio waves in the transmission direction can be calculated based on the ray data in the transmission direction (i.e., the direction of the normal path). Furthermore, the received power of the radio waves in the reception direction can be calculated based on the ray data in the reception direction (i.e., the direction of the reversed path) which is the reversed transmission direction.

[0142] In S610, as shown in Figure 10B, it is determined whether, for example, the reflection direction at reflection point P6 is close to the reception direction to radar R, that is, whether the angle between the reflection direction and the reception direction is less than or equal to a predetermined value. If the determination is positive, the process proceeds to S620; on the other hand, if the determination is negative, this process is terminated.

[0143] To determine the angle between the reflection direction and the reception direction, the dot product of the direction vector of the reflection direction and the direction vector of the reception direction may be used, similar to S520.

[0144] In S620, the attenuation is adjusted according to the degree of agreement between the reflection direction and the reception direction, and the process is terminated. For example, if the degree of agreement between both directions is high (i.e., the angle between the two directions is small), the power of the radio waves in at least one direction is reduced, as described above.

[0145] [1-5. Effects, etc.] According to this first embodiment, the following effects can be obtained.

[0146] (1a) In this first embodiment (for example, Examples 1 and 3), the power of the radio waves along the normal path to the ray collision site can be determined. Furthermore, based on the power of the radio waves along the normal path, the power of the radio waves along the reverse path from the ray collision site can be determined.

[0147] With this configuration, in this first embodiment, the simulation device 1 offers the advantages of high versatility and low computational load.

[0148] In other words, the power of the radio waves in the reverse path can be determined from the power of the radio waves in the normal path, thus reducing the computational load in the simulation. Furthermore, in this first embodiment, calculations can be performed without being limited by the state of the object to which the ray is projected (for example, the type of object the ray collides with or the position of the object), which has the advantage of being highly versatile.

[0149] (1b) In this first embodiment, when determining the power of the radio waves along the reverse path, the calculation can be made by taking into account the decrease in power at the starting point of the reverse path. That is, the power when the radio waves are emitted from the starting point of the reverse path can be used, and thereafter the propagation distance of the radio waves and the attenuation of the radio waves at the collision position can be subtracted to determine the power of the radio waves incident on the radar R (i.e., the received power).

[0150] (1c) In this first embodiment, the degree of agreement between the direction of the normal path and the direction of the reverse path may be determined, and if the degree of agreement is higher than a predetermined value, power may be removed from one of the paths, or power may be reduced from at least one of the paths.

[0151] For example, the degree of agreement can be determined based on the angle between the direction of the normal path and the direction of the reverse path. Alternatively, the degree of agreement may be determined based on the dot product of the vectors of the direction of the normal path and the direction of the reverse path.

[0152] (1d) In this first embodiment, when processing is performed on a path in the reverse direction, the number of reflections may be set for the ray that is to be processed.

[0153] For example, as shown in Figure 11, the display screen 14 of the display device 13 may be provided with an operation unit 13a that allows the number of reflections to be set manually or by other means. The number of reflections can be set by operating this operation unit 13a with a mouse or the like.

[0154] (1e) In this first embodiment, the function for processing the reverse path may be switched to either perform or stop.

[0155] For example, as shown in Figure 11, the display screen 14 of the display device 13 may be provided with an operation unit 13b that can be set to be executed or stopped manually. By operating this operation unit 13b with a mouse or the like, the function that processes the reverse path can be executed or stopped.

[0156] (1f) In this first embodiment, when processing is performed on a reverse path, the path generated by the processing (i.e., the reverse path) may be displayed on the display device 13 in a manner that distinguishes it from other paths (for example, the normal path described above). The display screen of the display device 13 may display only the normal path, only the reverse path, or both the normal path and the reverse path, distinguished by, for example, color. The display switching may be performed manually using the operation unit 13c of the display screen 14 as shown in Figure 11.

[0157] (1g) In this first embodiment (for example, Examples 2 and 3), the power of the radio waves in the normal path from when a ray is emitted from radar R until it returns to radar R can be determined. Furthermore, based on the power of the radio waves in the normal path, the power of the radio waves in the inverted path of the ray can be determined.

[0158] With this configuration, in this first embodiment, the simulation device 1 offers the advantages of high versatility and low computational load.

[0159] More specifically, since the direction of the paths is reversed between the normal path and the inverted path, the power of the radio waves in the inverted path can be determined based on the ray data when the normal path is inverted. In other words, the power of the radio waves in the inverted path can be determined from the power of the radio waves in the normal path (for example, the received power at radar R). That is, the power of the radio waves in the normal path can be used as the power of the radio waves in the inverted path, thus reducing the computational load in the simulation.

[0160] Furthermore, this first embodiment has the advantage of being highly versatile because it can perform calculations without being limited by the state of the object to which the ray is projected (for example, the type of object the ray collides with or the position of the object).

[0161] (1h) In this first embodiment, the degree of agreement between the direction of the normal path and the direction of the reverse path may be determined, and if the degree of agreement is higher than a predetermined value, power may be removed from one of the paths, or power may be reduced from at least one of the paths.

[0162] For example, the degree of agreement can be determined based on the angle between the direction of the normal path and the direction of the reversed path. Alternatively, the degree of agreement may be determined based on the dot product of the vectors of the direction of the normal path and the direction of the reversed path.

[0163] (1i) In this first embodiment, when processing is performed on a path in the reverse direction, the number of reflections may be set for the ray that is to be processed.

[0164] For example, as shown in Figure 11, the display screen 14 of the display device 13 may be provided with an operation unit 13d that allows the number of reflections to be set manually or by other means. The number of reflections can be set by operating this operation unit 13d with a mouse or the like.

[0165] (1j) In this first embodiment, the function that performs processing related to the reverse path may be switched to perform or stop.

[0166] For example, as shown in Figure 11, the display screen 14 of the display device 13 may be provided with an operation unit 13e that can be set to be executed or stopped manually. By operating this operation unit 13e with a mouse or the like, the function that performs processing related to the inversion path can be executed or stopped.

[0167] (1k) In this first embodiment, when processing is performed on the inverted path, the path generated by the processing (i.e., the inverted path) may be displayed on the display device 13 in a manner that distinguishes it from other paths (for example, the normal path described above). The display screen of the display device 13 may display only the normal path, only the inverted path, or both the normal path and the inverted path, distinguished by, for example, color. The display switching may be performed manually using the operation unit 13f of the display screen 14 as shown in Figure 11.

[0168] [1-6. Correspondence] Next, the relationship between this disclosure and this first embodiment will be explained.

[0169] The sensor corresponds to radar R, the simulation device corresponds to simulation device 1, the normal direction processing unit corresponds to control unit 11 and the processing in control unit 11 (for example, processing S100 to S160), the reverse direction processing unit corresponds to control unit 11 and the processing in control unit 11 (for example, processing S260), the route addition processing unit corresponds to control unit 11 and the processing in control unit 11 (for example, processing S360), and the display device corresponds to display device 13.

[0170] [2. Second Embodiment] The second embodiment has the same basic configuration as the first embodiment, so the differences from the first embodiment will be described below. The same reference numerals as in the first embodiment indicate the same components, and refer to the preceding description.

[0171] In this second embodiment, as shown in Figure 13, the simulation device 31 includes a first processing unit 33 and a second processing unit 35. The first processing unit 33 includes a GPU 37, a ROM 39, and a RAM 41. The second processing unit 35 includes a CPU 43, a ROM 45, and a RAM 47.

[0172] As is well known, the GPU 37 is a processing unit capable of executing operations related to each ray in parallel at high speed. Note that only the essential parts of the simulation device 31 are shown in Figure 13.

[0173] In this second embodiment, processing is performed on each ray in the same manner as in the second embodiment shown in Figure 7B.

[0174] In other words, in this second embodiment, the processes S700 to S780 in the flowchart shown in Figure 12 are performed. Note that the processing content of S700 to S780 is the same as the processing content of S300 to S380 in Figure 7B, so its explanation is omitted.

[0175] Next, we will explain the essential parts of the overall ray tracing process based on the flowchart in Figure 14.

[0176] First, in the S800, the direction of the ray is determined.

[0177] In the subsequent S810, output memory is allocated for GPU33.

[0178] In the subsequent S820, output memory is allocated for CPU 43.

[0179] In the subsequent S830, toy tracing is performed using GPU33, and the results are written to GPU memory (for example, RAM41).

[0180] In the subsequent S840, data from the GPU memory (e.g., RAM41) is sent to the CPU memory (e.g., RAM47).

[0181] In the subsequent S850, data related to polygonal waves is extracted from the CPU memory data.

[0182] In the subsequent S860, the data related to the polygonal wave is duplicated, the transmission direction and reception direction are reversed, and this process is temporarily terminated.

[0183] This second embodiment provides the same effects as the first embodiment. Furthermore, since this second embodiment includes a first processing unit 33 and a second processing unit 35, it has the advantage of being able to perform calculations in ray tracing at high speed.

[0184] [3. Other Embodiments] Although embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the embodiments described above and can take various forms.

[0185] (3a) The present disclosure is not limited to simulation devices that perform ray tracing of radar radio waves (i.e., radar waves), but is also applicable to simulation devices that perform ray tracing of ultrasonic waves emitted from sonar (i.e., ultrasonic sensors).

[0186] In other words, the energy of the ultrasonic waves emitted from the sonar (for example, the intensity of the ultrasonic waves) is attenuated along the path of a ray simulating those ultrasonic waves, depending on the propagation distance of the ultrasonic waves and the material of the object they collide with. Therefore, the power corresponding to the energy of the ultrasonic waves that hit the object and return to the sonar may be determined by taking this attenuation into account.

[0187] (3b) The present disclosure can be applied to a simulation device that performs ray tracing of laser light emitted from a LiDAR. LiDAR is an abbreviation for Light Detection And Ranging, and as is well known, it is a device that uses laser light to measure the distance and shape of an object.

[0188] In other words, the energy of the laser beam emitted from the LiDAR (for example, the intensity of the laser beam) is attenuated along the path of a ray simulating that laser beam, depending on the propagation distance of the laser beam and the material of the object it collides with. Therefore, the power corresponding to the energy of the laser beam that hits the object and returns to the LiDAR may be calculated by taking this attenuation into account.

[0189] (3c) The processing and methods in the simulation apparatus described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program.

[0190] Alternatively, the processing and methods in the simulation apparatus described herein may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits.

[0191] Alternatively, the processing and methods in the simulation apparatus described herein may be implemented by one or more dedicated computers, each comprising a processor and memory programmed to perform one or more functions, and a processor comprising one or more hardware logic circuits.

[0192] Furthermore, the computer program may be stored on a computer-readable, non-transitional tangible recording medium as instructions to be executed by the computer. The method for realizing the functions of each part included in the simulation device does not necessarily have to include software; all of its functions may be realized using one or more hardware components.

[0193] (3d) The above-mentioned simulation apparatus can also be realized in various forms, including a configuration that includes the simulation apparatus as a component, a program for making the computer of the simulation apparatus function, a non-transition tangible recording medium such as a semiconductor memory on which this program is recorded, and a control method.

[0194] (3e) Multiple functions of one component in each of the above embodiments may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configurations of each of the above embodiments may be omitted. Furthermore, at least some of the configurations of each of the above embodiments may be added to or replaced with the configurations of other embodiments. [Technical Concept Disclosed in This Specification] [Item 1] A simulation device (1) that simulates the path of a sensor wave when a sensor (R) is emitted from a sensor, using a pseudo-ray that simulates the sensor wave, comprising: a normal direction processing unit (11, S100 to S160) configured to determine the power corresponding to the energy of the sensor wave at the collision position in accordance with the attenuation of the energy of the sensor wave generated in the normal path from the sensor to the collision position of the object when the pseudo-ray is emitted from the sensor and the pseudo-ray collides with an object; and a reverse direction processing unit (11, S260) configured to determine the power corresponding to the energy of the sensor wave in the reverse path when the pseudo-ray is reflected once or more times before reaching the collision position of the object, by switching the incident direction of the sensor wave at the collision position of the pseudo-ray to a direction that returns to the sensor, and determining the power corresponding to the energy of the sensor wave in the reverse path.

[0195] [Item 2] A simulation device as described in Item 1, wherein, when determining the power corresponding to the energy of the sensor wave in the reverse path, the device is configured to calculate by subtracting the amount of power decrease at the starting point of the reverse path.

[0196] [Item 3] A simulation device according to Item 1 or Item 2, wherein the device is configured to determine the degree of agreement between the direction of the normal path and the direction of the reverse path, and, if the degree of agreement is higher than a predetermined value, to eliminate the power in one of the paths or reduce the power in at least one of the paths.

[0197] [Item 4] A simulation device as described in Item 3, wherein the degree of agreement is determined based on the angle between the direction of the normal path and the direction of the reverse path.

[0198] [Item 5] A simulation device as described in Item 4, wherein the degree of agreement is determined based on the dot product of the vectors of the direction of the normal path and the direction of the reverse path.

[0199] [Item 6] A simulation device according to any one of items 1 to 5, wherein, when processing is performed in the reverse direction processing unit, the number of reflections of the pseudo-ray being processed can be set.

[0200] [Item 7] A simulation device according to any one of items 1 to 6, wherein the function of performing the processing in the reverse processing unit is configured to be able to be performed or stopped.

[0201] [Item 8] A simulation device according to any one of items 1 to 7, wherein when processing is performed in the reverse processing unit, the device is configured to have a function to display the path generated by the processing on a display device (13) in a manner that distinguishes it from other paths.

[0202] [Item 9] A simulation device (1) that simulates the path of a sensor wave when a sensor (R) emits a sensor wave using a pseudo-ray that simulates the sensor wave, comprising: a normal direction processing unit (11, S100 to S160) configured to determine the power corresponding to the energy of the sensor wave incident on the sensor in accordance with the attenuation of the energy of the sensor wave generated in the normal path of the pseudo-ray from the sensor until it is emitted and incident on the sensor, when the pseudo-ray is reflected by an object and incident on the sensor; and a path addition processing unit (11, S360) configured to add a reversed path which is the transmission path that is the normal path of the pseudo-ray from emission to incidence.

[0203] [Item 10] A simulation device as described in Item 9, configured to determine the power corresponding to the energy of the sensor wave in the inverted path based on the power corresponding to the energy of the sensor wave in the normal path.

[0204] [Item 11] A simulation device according to Item 9 or Item 10, wherein the device is configured to determine the degree of agreement between the direction of the normal path and the direction of the reversed path, and, if the degree of agreement is higher than a predetermined value, to eliminate the power in one of the paths or reduce the power in at least one of the paths.

[0205] [Item 12] A simulation apparatus as described in Item 11, wherein the degree of agreement is determined based on the angle between the direction of the normal path and the direction of the reversed path.

[0206] [Item 13] A simulation device as described in Item 12, wherein the degree of agreement is determined based on the dot product of the vectors of the direction of the normal path and the direction of the reversed path.

[0207] [Item 14] A simulation device according to any one of items 9 to 13, wherein, when processing is performed in the path addition processing unit, the simulation device is configured to set the number of reflections for the pseudo-ray being processed.

[0208] [Item 15] A simulation device according to any one of items 9 to 14, wherein the function of performing the processing in the route addition processing unit is configured to be able to be performed or stopped.

[0209] [Item 16] A simulation device according to any one of items 9 to 15, wherein when processing is performed in the route addition processing unit, the device is configured to have a function to display the route generated by the processing on a display device (13) in a manner that distinguishes it from other routes.

Claims

1. A simulation device (1) that simulates the path of a sensor wave emitted from a sensor (R) using a pseudo-ray that simulates the sensor wave, comprising: a normal direction processing unit (11, S100 to S160) configured to determine the power corresponding to the energy of the sensor wave at the collision position in accordance with the attenuation of the energy of the sensor wave generated in the normal path from the sensor to the collision position of the object when the pseudo-ray is emitted from the sensor and the pseudo-ray collides with an object; and a reverse direction processing unit (11, S260) configured to determine the power corresponding to the energy of the sensor wave in the reverse path when the pseudo-ray is reflected once or more times before reaching the collision position of the object.

2. A simulation apparatus according to claim 1, wherein, when determining the power corresponding to the energy of the sensor wave in the reverse path, the simulation apparatus is configured to calculate by subtracting the amount of power decrease at the starting point of the reverse path.

3. A simulation apparatus according to claim 1, wherein the apparatus is configured to determine the degree of agreement between the direction of the normal path and the direction of the reverse path, and, if the degree of agreement is higher than a predetermined value, to remove the power in one of the paths or reduce the power in at least one of the paths.

4. A simulation apparatus according to claim 3, wherein the degree of agreement is determined based on the angle between the direction of the normal path and the direction of the reverse path.

5. A simulation apparatus according to claim 4, wherein the degree of agreement is determined based on the dot product of the vectors of the direction of the normal path and the direction of the reverse path.

6. A simulation apparatus according to claim 1, wherein, when processing is performed in the reverse direction processing unit, the number of reflections of the pseudo-ray being processed can be set.

7. A simulation apparatus according to claim 1, wherein the function of performing processing in the reverse processing unit is configured to be able to be performed or stopped.

8. A simulation apparatus according to claim 1, wherein, when processing is performed in the reverse processing unit, the simulation apparatus is configured to have a function to display on a display device (13) the path generated by the processing in a manner that distinguishes it from other paths.

9. A simulation device (1) that simulates the path of a sensor wave when a sensor (R) is emitted from the sensor, using a pseudo-ray that simulates the sensor wave, comprising: a normal direction processing unit (11, S100 to S160) configured to determine the power corresponding to the energy of the sensor wave incident on the sensor in accordance with the attenuation of the energy of the sensor wave generated in the normal path of the pseudo-ray from the sensor until it is emitted from the sensor and incident on the sensor; and a path addition processing unit (11, S360) configured to add a reversed path which is the transmission path that is the normal path of the pseudo-ray from emission to incidence.

10. A simulation apparatus according to claim 9, configured to determine the power corresponding to the energy of the sensor wave in the inverted path based on the power corresponding to the energy of the sensor wave in the normal path.

11. A simulation apparatus according to claim 9, wherein the apparatus is configured to determine the degree of agreement between the direction of the normal path and the direction of the reversed path, and, if the degree of agreement is higher than a predetermined value, to remove the power in one of the paths or reduce the power in at least one of the paths.

12. A simulation apparatus according to claim 11, wherein the degree of agreement is determined based on the angle between the direction of the normal path and the direction of the reversed path.

13. A simulation apparatus according to claim 12, wherein the degree of agreement is determined based on the dot product of the vectors of the direction of the normal path and the direction of the reversed path.

14. A simulation apparatus according to claim 9, wherein, when processing is performed in the path addition processing unit, the simulation apparatus is configured to set the number of reflections for the pseudo-ray being processed.

15. A simulation apparatus according to claim 9, wherein the function of performing the processing in the route addition processing unit is configured to be able to be performed or stopped.

16. A simulation apparatus according to claim 9, wherein when processing is performed in the route addition processing unit, the simulation apparatus is configured to have a function to display on a display device (13) the route generated by the processing in a manner that distinguishes it from other routes.

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