Estimation method, arithmetic device, and mobile body
Patent Information
- Application Number
- PCT/JP2026/012806
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-27
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026012806_01102026_PF_FP_ABST
Abstract
Description
Estimation method, arithmetic device, and moving object
[0001] The present disclosure relates to a method for estimating the position and orientation of a moving object. The present disclosure also relates to an arithmetic device configured to execute the method, and to a moving object equipped with the arithmetic device.
[0002] Japanese Patent Application Publication No. 2024-124767 discloses a system that performs control to cause a drone, which is an example of an aircraft, to reach a target position using a GPS (Global Positioning System) positioning value.
[0003] There is a demand for reducing the arithmetic processing load for improving the accuracy of a moving object reaching a target position.
[0004] A first exemplary aspect that the present disclosure can provide is a method for estimating the position and orientation of a moving object executed by at least one arithmetic device, the method comprising: performing short-range wireless communication conforming to the UWB wireless communication standard with an external communication device using a plurality of communication devices, thereby acquiring a plurality of distance measurement values corresponding to distances of the plurality of communication devices to the external communication device; acquiring a value of at least one first parameter among six parameters capable of specifying the position and orientation using a signal output from at least one sensor mounted on the moving object; acquiring values of a plurality of second parameters different from the first parameter among the six parameters using the plurality of distance measurement values; specifying the position of each of the plurality of communication devices using the six parameters; and estimating the position and orientation of the moving object based on the positions of the plurality of communication devices.
[0005] A second exemplary aspect that the present disclosure can provide is an arithmetic device configured to execute the estimation method according to the first exemplary aspect.
[0006] A third exemplary aspect that the present disclosure can provide is a moving object equipped with the arithmetic device according to the second exemplary aspect.
[0007] By using multiple communication devices to perform short-range wireless communication with an external communication device in accordance with the UWB wireless communication standard, and obtaining multiple distance measurement values corresponding to the distance of the multiple communication devices to the external communication device, the position of each communication device can be determined using a function with six parameters that can identify the position and attitude of a moving object. By referring to these positions, the position and attitude of the moving object can be estimated with high accuracy, thereby increasing the probability of the moving object reaching its target position. These six parameters include, for example, the values of three coordinate axes that form a Cartesian coordinate system and the rotation angles around each of these three coordinate axes.
[0008] According to the configurations described in each of the above examples, the value of at least one of the parameters can be treated as known using the signal output from a sensor mounted on the mobile body that detects a physical quantity corresponding to at least one of the six parameters. This reduces the number of variables in the function used to determine the position of each communication device. Therefore, the computational processing load required to increase the accuracy of the mobile body reaching the target position can be reduced.
[0009] This figure illustrates a drone and landing / takeoff port included in a communication system according to one embodiment. The functional configuration of the drone and landing / takeoff port in Figure 1 is illustrated. An example of the communication flow between the first port-side communication device and the first drone-side communication device in Figure 2 is shown. Another example of the communication flow between the first port-side communication device and the first drone-side communication device in Figure 2 is shown. This figure is a diagram illustrating the processing performed by the drone-side communication device in Figure 2. An example of the processing flow performed by the drone-side communication device in Figure 2 is illustrated.
[0010] The embodiments will be described in detail below with reference to the attached drawings. In the drawings used in the following description, the scale has been appropriately changed to make each element recognizable.
[0011] Figure 1 illustrates the appearance of a drone 2 and a landing / takeoff port 3 included in a communication system 1 according to one embodiment. The communication system 1 is configured to land the drone 2 at a target position 31 at the landing / takeoff port 3 using communication compliant with the UWB (Ultra-Wide Band) wireless communication standard. The drone 2 is an example of an aircraft.
[0012] An example of a UWB wireless communication standard is channel number 9 in IEEE 802.15.4z (center frequency: 7987.2 MHz, frequency bandwidth: 499.2 MHz).
[0013] Drone 2 is equipped with multiple rotors 21. In this example, Drone 2 is equipped with four rotors 21.
[0014] As illustrated in Figure 2, the drone 2 is equipped with multiple drone-side communication devices 22. In this example, the multiple drone-side communication devices 22 include a first drone-side communication device 221, a second drone-side communication device 222, a third drone-side communication device 223, and a fourth drone-side communication device 224.
[0015] On the other hand, the arrival / departure port 3 is equipped with multiple port-side communication devices 32. In this example, the multiple port-side communication devices 32 include a first port-side communication device 321, a second port-side communication device 322, a third port-side communication device 323, and a fourth port-side communication device 324.
[0016] Each of the multiple drone-side communication devices 22 and the multiple port-side communication devices 32 has a well-known configuration that enables bidirectional communication in accordance with the aforementioned UWB wireless communication standard. In other words, each of the multiple drone-side communication devices 22 and the multiple port-side communication devices 32 is equipped with an antenna that has radio wave transmission and reception functions.
[0017] Drone 2 is equipped with a drone-side control device 23. The drone-side control device 23 is configured to control the radio wave transmission operation of each of the multiple drone-side communication devices 22. The drone-side control device 23 is configured to acquire information superimposed on the radio waves received by each of the multiple drone-side communication devices 22.
[0018] The arrival / departure port 3 is equipped with a port-side control device 33. The port-side control device 33 is configured to control the radio wave transmission operation of each of the multiple port-side communication devices 32. The port-side control device 33 is configured to acquire information superimposed on the radio waves received by each of the multiple port-side communication devices 32.
[0019] Referring to Figure 3, the positioning process performed between the first drone-side communication device 221 and the first port-side communication device 321 will be explained.
[0020] The port-side control device 33 causes the first port-side communicator 321 to transmit a first start signal p1 at time t1. The first start signal p1 is received by the first drone-side communicator 221 at time t2.
[0021] The drone-side control device 23, in response to the first start signal p1, causes the first drone-side communicator 221 to transmit a first response signal r1 at time t3. The first response signal r1 is received by the first port-side communicator 321 at time t4.
[0022] The port-side control device 33, in response to the first response signal r1, causes the first port-side communicator 321 to transmit a first completion signal f1 at time t5. The first completion signal f1 is configured to include information that identifies times t1, t4, and t5. The first completion signal f1 is received by the first drone-side communicator 221 at time t6.
[0023] The drone-side control device 23 holds information that identifies time points t2, t3, and t6. Adding the information that identifies time points t1, t4, and t5 provided by the first completion signal f1, the drone-side control device 23 calculates the following equation to obtain the distance d11 between the first port-side communicator 321 and the first drone-side communicator 221. The symbol c is the speed of light. d11 = c[(t4 - t1) - (t3 - t2) + (t6 - t3) - (t5 - t4)] / 4
[0024] Similarly, the drone-side control device 23 acquires the distance d21 between the second port-side communication device 322 and the first drone-side communication device 221, the distance d31 between the third port-side communication device 323 and the first drone-side communication device 221, and the distance d41 between the fourth port-side communication device 324 and the first drone-side communication device 221. The positions of each port-side communication device 32 are examples of reference positions. The acquired distances are examples of distance measurement values.
[0025] In this embodiment, the distance between each of the four port-side communication devices 32 is obtained in the same manner for each of the second drone-side communication device 222, the third drone-side communication device 223, and the fourth drone-side communication device 224. Therefore, a total of 16 distance values are obtained.
[0026] In the above example, the start signal is transmitted from multiple port-side communicators 32 mounted on the arrival / departure port 3. However, as illustrated in Figure 4, the start signal may also be transmitted from multiple drone-side communicators 22 mounted on the drone 2.
[0027] In this case, the acquired distance information is located at the departure / arrival port, so in order for drone 2 to determine its own position, the acquired distance information is transmitted from departure / arrival port 3 to drone 2. For example, the transmission of distance information is performed using communication compliant with the UWB wireless communication standard.
[0028] However, communication compliant with the UWB wireless communication standard has the characteristic that the power consumption burden is greater on the receiving side than on the transmitting side. As an alternative to avoid this problem, distance information can be transmitted using signals that do not comply with the UWB wireless communication standard.
[0029] Specifically, as illustrated in Figure 2, the drone 2 and the landing / takeoff port 3 may be equipped with auxiliary communication devices 24 and 34, respectively. The auxiliary communication devices 24 and 34 are configured to send and receive auxiliary signals AX via short-range wireless communication that does not conform to the UWB wireless communication standard. Examples of such short-range wireless communication include Bluetooth®, Bluetooth Low Energy®, ZigBee®, and Wi-Fi®.
[0030] The drone-side control device 23 is equipped with a computing device. The computing device is configured to perform processing to estimate the position (positioning value) and attitude of the drone 2. As illustrated in Figure 5, the reference position of the drone 2 is specified as coordinates (X, Y, Z) using a world coordinate system consisting of the X, Y, and Z axes. In addition, in order to specify the attitude of the drone 2, a local coordinate system consisting of the x, y, and z axes is defined with the reference position as the origin. The attitude of the drone 2 is specified by the pitch angle, roll angle, and yaw angle. The pitch angle is defined as the rotation angle around the x axis. The roll angle is defined as the rotation angle around the y axis. The yaw angle is defined as the rotation angle around the z axis. Note that the rotation angles are defined with the right-handed system as the positive direction.
[0031] Therefore, in this example, the coordinates P1 of the first drone-side communication device 221, P2 of the second drone-side communication device 222, P3 of the third drone-side communication device 223, and P4 of the fourth drone-side communication device 224 are expressed by the following equations, respectively. Here, Rα, Rβ, and Rγ are rotation matrices, and are expressed by the following equations.
[0032] In the above equation, the distance ax between the drone-side communication devices 22 along the x-axis and the distance ay between the drone-side communication devices 22 along the y-axis are known. Therefore, the coordinates Pn of the nth drone-side communication device 22 can be expressed as a function of six parameters X, Y, Z, α, β, and γ. Pn(X, Y, Z, α, β, γ)
[0033] If the coordinates of the m-th port-side communicator 32 are denoted by Qm, the relationship between the distance measurement value dnm between the n-th drone-side communicator 22 and the m-th port-side communicator 32 is given by the following equation. The value of Qm is known. dnm = |Pn - Qm|
[0034] The position and attitude of drone 2 can be estimated using the least squares method or similar techniques from 16 different equations (d11 to d44) obtained based on 16 distance measurement values.
[0035] As an alternative example, assuming that the reference position and attitude of drone 2 are (Xa, Ya, Za) and (αa, βa, γa), respectively, and that the assumed coordinates of the nth drone-side communicator 22 are Pan, the relationship between the assumed distance measurement value danm between the nth drone-side communicator 22 and the mth port-side communicator 32 is expressed by the following equation: danm = |Pan - Qm|
[0036] Next, the error between the 16 hypothetical distance values (da11 to da44) obtained as described above and the 16 actually obtained distance values (d11 to d44) is calculated. By calculating this error for various hypothetical reference positions and attitudes, a combination of hypothetical reference positions and attitudes that minimizes this error can be identified. This combination can then be estimated as the position and attitude of drone 2.
[0037] Such a computing device can be realized by at least one dedicated integrated circuit equipped with memory elements on which a computer program for performing the above processing is pre-installed. Examples of dedicated integrated circuits include microcontrollers, ASICs, and FPGAs.
[0038] Alternatively, the arithmetic unit may be implemented by at least one general-purpose microprocessor operating in cooperation with at least one general-purpose memory. Examples of general-purpose microprocessors include CPUs, MPUs, and GPUs. Examples of general-purpose memory include ROMs and RAMs. In this case, the ROM may store a computer program for implementing the function. The general-purpose microprocessor selects at least a portion of the program stored in the ROM and loads it into the RAM, and then works with the RAM to execute the above-described process. The arithmetic unit may also be implemented by a combination of a general-purpose microprocessor and a dedicated integrated circuit.
[0039] As illustrated in Figure 2, the drone 2 is equipped with a sensor 25. The sensor 25 is configured to detect a physical quantity corresponding to at least one of the six parameters mentioned above and to output a detection signal corresponding to that physical quantity. The detection signal is received by the arithmetic unit of the drone-side control device 23.
[0040] As an example, the sensor 25 may be an atmospheric pressure sensor. The value of atmospheric pressure detected by the atmospheric pressure sensor can correspond to altitude. Among the six parameters described with reference to Fig. 5, the value of the Z-axis coordinate can correspond to altitude. Alternative examples of the sensor 25 capable of acquiring the Z-axis coordinate value include an ultrasonic sensor, a laser sensor, and the like.
[0041] The arithmetic device acquires the value of Z in response to receiving a detection signal. The Z-axis coordinate value is an example of a first parameter. In this case, the arithmetic device treats the value of Z as a known value among the function Pn(X, Y, Z, α, β, γ) representing the coordinates of each drone-side communication device 22, and estimates the position and attitude of the drone 2 through processing of specifying the values of the remaining five unknown parameters. The five parameters are an example of a second parameter.
[0042] It is not necessary for the physical quantity detected by the sensor 25 and any of the six parameters to have a one-to-one correspondence. As an alternative example, the sensor 25 may include at least one of an orientation sensor, an acceleration sensor, and a gyro sensor. The physical quantity detected by the at least one sensor can correspond to at least one of the pitch angle α, the roll angle β, and the yaw angle γ among the six parameters.
[0043] The arithmetic device acquires at least one value among the pitch angle α, the roll angle β, and the yaw angle γ in response to receiving a detection signal. At least one of the pitch angle α, the roll angle β, and the yaw angle γ is an example of the first parameter. In this case, the arithmetic device treats at least one value among α, β, and γ as a known value among the function Pn(X, Y, Z, α, β, γ) representing the coordinates of each drone-side communication device 22, and estimates the position and attitude of the drone 2 through processing of specifying the values of the remaining at least three unknown parameters. The at least three parameters are an example of the second parameter.
[0044] The above two examples may be combined. That is, in response to receiving a detection signal, at least one value among the pitch angle α, the roll angle β, and the yaw angle γ and the value of the Z-axis coordinate may be acquired.
[0045] By performing short-range wireless communication conforming to the UWB wireless communication standard with a port-side communication device 32 using a plurality of drone-side communication devices 22, if a plurality of distance measurement values corresponding to the distances of the plurality of drone-side communication devices 22 to the port-side communication device 32 can be acquired, the position of each drone-side communication device 22 can be specified using a function that takes six parameters capable of specifying the position and posture of the drone 2 as variables. By referencing the positions, the position and posture of the drone 2 can be estimated with high accuracy, so the accuracy of the drone 2 reaching the target position 31 can be improved. The six parameters include, for example, values of three coordinate axes forming an orthogonal coordinate system and rotation angles about each of the three coordinate axes.
[0046] According to the configuration according to the present embodiment, the value of the at least one parameter can be treated as a known value using a detection signal output from a sensor 25 that is mounted on the drone 2 and detects a physical quantity corresponding to at least one of the six parameters. This makes it possible to reduce the number of variables in the function used to specify the position of each drone-side communication device 22. Therefore, the arithmetic processing load for improving the accuracy of the drone 2 reaching the target position 31 can be reduced.
[0047] In addition, when the sensor 25 is used for purposes other than estimating the position and posture of the drone 2, the detection signal output for the original purpose can be used in combination to estimate the position and posture of the drone 2 with higher accuracy. This makes it possible to improve the versatility of the sensor 25.
[0048] Note that when the flight of the drone 2 is controlled so as to maintain a predetermined altitude and posture, at least one value of the Z-axis coordinate, pitch angle α, roll angle β, and yaw angle γ can be treated as known, and acquisition of the detection signal output from the sensor 25 for the known value can be omitted.
[0049] In the above embodiment, distance measurement processing using short-range wireless communication compliant with the UWB wireless communication standard and acquisition of detection signals output from sensor 25 are performed in parallel. However, the position and attitude of drone 2 may also be estimated based on the output from sensor 25 alone. For example, the position of drone 2 can be estimated by combining the GPS signal and the output from the barometric pressure sensor. Alternatively, the attitude of drone 2 can be estimated by appropriately combining the outputs from a compass sensor, acceleration sensor, gyro sensor, etc. Since these methods are well known, a detailed explanation will be omitted.
[0050] Figure 6 illustrates the processing flow that may be executed by the computing device of the drone-side control device 23 in such a case.
[0051] The computing unit first receives the detection signal output from the sensor 25 (STEP 1). Next, the computing unit determines whether the reliability of the sensor 25 is below a threshold based on the received detection signal (STEP 2). The term "sensor reliability" as used in this disclosure includes not only the reliability of the sensor itself, which depends on whether or not it is faulty, but also the reliability of the detection result, which depends on the operating environment.
[0052] For example, the level or signal-to-noise ratio of the detected signal may be referenced. If its magnitude falls below a threshold, the reliability of the sensor 25 is judged to be below the threshold. Alternatively, the degree of variability of the detected signal may be referenced. If its degree exceeds a threshold, the reliability of the sensor 25 is judged to be below the threshold.
[0053] If the reliability of sensor 25 is determined not to be below the threshold (YES in STEP 2), the computing unit uses the output from sensor 25 to estimate the position and attitude of drone 2 (STEP 3).
[0054] If the reliability of sensor 25 is determined to be below a threshold (NO in STEP 2), the computing unit initiates distance measurement processing using short-range wireless communication compliant with the UWB wireless communication standard (STEP 4). In this case, as explained with reference to Figure 5, the computing unit obtains multiple distance values corresponding to the distances of multiple drone-side communicators 22 to the port-side communicator 32 obtained through the distance measurement processing, and estimates the position and attitude of drone 2 based on the positions of the multiple drone-side communicators 22 identified using these multiple distance values (STEP 3).
[0055] According to the configuration in this example, even if the reliability of the sensor 25, which detects physical quantities for estimating the position and attitude of the drone 2, deteriorates, this deficiency can be compensated for through distance measurement processing using short-range wireless communication compliant with the UWB wireless communication standard. On the other hand, the opportunities for initiating distance measurement processing, which has a relatively high computational load, can be minimized. Therefore, the accuracy of the drone 2 reaching the target position 31 can be increased while suppressing an increase in the computational load.
[0056] The configurations described herein are merely examples to facilitate understanding of this disclosure. Each configuration example may be modified and combined with other configuration examples as appropriate, without departing from the spirit of this disclosure.
[0057] In the above embodiment, the function representing the position coordinates of the multiple drone-side communication devices 22 includes three coordinate values that form a Cartesian coordinate system as parameters. However, three coordinate values that form a polar coordinate system or a cylindrical coordinate system may also be included as parameters.
[0058] The "UWB wireless communication standard" used in the above embodiment example originates from a standardization standard compliant with IEEE 802.15. However, this expression is not intended to limit the scope to that standard. Any short-range wireless communication standard that can determine the relative positions of communication devices with high accuracy and has advantages such as low power consumption and low interference with other communications may be adopted. For example, distance values may be obtained by short-range wireless communication compliant with the Bluetooth Low Energy (registered trademark) standard.
[0059] In the above embodiment, the drone-side control device 23 is equipped with a computing device that performs processing to estimate the position and attitude of the drone 2. However, this computing device may also be equipped in the port-side control device 33. In this case, the data indicating the estimated position and attitude of the drone 2 can be transmitted to the drone 2 using, for example, the auxiliary communication device 34 described above.
[0060] In the above embodiment, the communication system 1 is used to determine the position of the drone 2 relative to the target position. However, the communication system 1 may also be used to determine the position of an aircraft capable of carrying a person. Alternatively, the communication system 1 may be used to determine the position of a mobile body other than the drone 2. Examples of such mobile bodies include vehicles, trains, and ships. Such mobile bodies do not necessarily require a driver.
[0061] The contents of Japanese Patent Application No. 2025-053797, filed on 27 March 2025, are incorporated herein by reference as forming part of this disclosure.
Claims
1. A method for estimating the position and attitude of a moving object, performed by at least one computing device, comprising: using a plurality of communication devices to perform short-range wireless communication with an external communication device in accordance with the UWB wireless communication standard, thereby obtaining a plurality of distance measurement values corresponding to the distance of the plurality of communication devices to the external communication device; using signals output from at least one sensor mounted on the moving object to obtain the value of at least one first parameter among six parameters that can identify the position and attitude; using the plurality of distance measurement values to obtain the values of a plurality of second parameters that are different from the first parameter among the six parameters; using the six parameters to identify the position of each of the plurality of communication devices; and estimating the position and attitude of the moving object based on the positions of the plurality of communication devices.
2. The estimation method according to claim 1, wherein the at least one first parameter includes coordinates corresponding to altitude, and the at least one sensor includes at least one of a barometric pressure sensor, an ultrasonic sensor, and a laser sensor.
3. The estimation method according to claim 1 or 2, wherein the at least one first parameter includes at least one of pitch angle, roll angle, and yaw angle, and the at least one sensor includes at least one of orientation sensor, acceleration sensor, and gyroscope sensor.
4. The estimation method according to any one of claims 1 to 3, wherein the moving body is an aerial vehicle.
5. A computing device configured to perform the estimation method described in any one of claims 1 to 4.
6. A mobile body equipped with the computing device described in claim 5.