Landing of a drone in an emergency scenario

Abstract

The invention relates to landing of a drone in an emergency scenario. An apparatus for causing a drone (UAV) to perform an emergency landing procedure is provided. The apparatus comprises a memory and a processing circuitry configured to cause the apparatus to at least determine candidate safe landing zones (SLZs) within an estimated current range of the UAV. Trajectories for causing the UAV to land in respective candidate SLZs are generated. A risk value is calculated, the risk value quantifying a third party risk associated with operation of the UAV along the respective trajectories to the respective candidate SLZs. A flight termination risk value is calculated, the flight termination risk value quantifying a third party risk associated with the UAV landing immediately at a current location. The lowest risk value is compared with the flight termination risk value, and a sequence is executed to operate the UAV along a trajectory to a selected one of the candidate SLZs, or to cause the UAV to land immediately.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to unmanned aerial vehicles, and in particular, to landing of unmanned aerial vehicles in emergency scenarios. BACKGROUND

[0002] Aircraft, particularly light aircraft and unmanned aerial vehicles (UAVs), often encounter unexpected conditions due to internal malfunctions or unexpected changes in the external environment, which present obstacles to achieving mission objectives. For example, loss of communication link or loss of navigation capability are unexpected conditions that can occur during operation of a UAV, and are scenarios that drive decision making in some emergency situations. Loss of communication link can render a UAV unable to communicate with a ground control station (GCS) that can remotely control the UAV. Loss of navigation capability can render a UAV unable to follow commanded waypoints or trajectories, requiring manual control by a remote pilot at the GCS.

[0003] Emergency scenarios can require a UAV to land at a location other than its intended landing point, but this can present a relatively large challenge for a UAV that has flown over some terrain. Current techniques for UAV landing in emergency scenarios include a simple "Return-To-Home" (RTH) function that causes a UAV to return to its takeoff location along a straight path above a specified height, an alternative landing point for this RTH function that uses the nearest landing point instead of the takeoff location (also known as a "rendezvous point"), or so-called "backtracking" in which a UAV follows its previous flight path or portion thereof to reach the takeoff location or an alternative landing point, following only the previously flown path. However, these solutions do not take into account third-party risks (risks to third parties), such as risks to people, road traffic, aircraft, structures, etc. in the spatial environment of the UAV. Therefore, existing solutions often do not perform as well as desired in certain environments, such as urban and suburban environments.

[0004] Accordingly, it would be desirable to have a system and method that takes into account at least some of the issues discussed above, as well as possibly other issues. SUMMARY

[0005] Example implementations of the present disclosure relate to improved techniques for landing of unmanned aerial vehicles (UAVs) in emergency scenarios. Example implementations provide an emergency management system and procedure for a UAV that can improve operational safety by allowing for automatic landing in emergency situations, while taking into account relative risks to third parties in the air and on the ground.

[0006] The programs in some example implementations can follow a system approach based on a tiered quantitative risk assessment that is performed by analyzing data encompassing factors that affect risk. This can allow for a data-driven risk assessment to be used in handling unexpected situations. As a means of avoiding flight termination or landing in an unsafe area in the event that a planned mission cannot continue, a safe landing zone (SLZ) can be introduced as an optional landing point.

[0007] Accordingly, the present disclosure includes, without limitation, the following example implementations.

[0008] Some example implementations provide a method of performing an emergency landing procedure for an unmanned aerial vehicle (UAV), the method comprising: determining candidate safe landing zones (SLZs) within an estimated current range of the UAV from a current location; generating a trajectory for the UAV to land in a respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ; calculating a risk value quantifying third-party risk associated with operation of the UAV along the respective trajectory to the respective candidate SLZ, a lowest risk value being associated with a trajectory to a selected one of the candidate SLZs from the current location; calculating a flight termination risk value quantifying third-party risk associated with the UAV immediately landing at the current location; performing a comparison of the lowest risk value and the flight termination risk value; and based on the comparison, performing a sequence to operate the UAV to reach the selected one of the candidate SLZs along the trajectory or to cause the UAV to immediately land at the current location.

[0009] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the UAV is part of an unmanned aerial system, the system further comprising a ground control station (GCS), the method being performed on the UAV, the sequence being performed autonomously without input from the GCS.

[0010] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the UAV is part of an unmanned aerial system, the system further comprising a ground control station (GCS), the method being performed at the GCS, the sequence being performed by remotely controlling the UAV from the GCS.

[0011] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the method further comprises: generating or receiving a risk map for a geographic region of operation of the UAV, the risk map comprising risk zones of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV in the risk zones, wherein the trajectory intersects a plurality of the risk zones in the risk map, and the risk value is calculated based on the respective risk weight factors.

[0012] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, generating the trajectory comprises, for the candidate SLZ, interpolating a straight line from the current location to the candidate SLZ, thereby generating the trajectory to the candidate SLZ, and computing the risk value comprises, for the trajectory: separating the trajectory into segments at intersections with the one or more risk zones; and computing the risk value for the candidate SLZ from the segments and risk weight factors for the one or more risk zones.

[0013] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the straight line is of a particular distance and comprises a total number of discrete points over the particular distance, separating the trajectory comprises, for each of the one or more risk zones: determining a ratio of a number of the discrete points on the trajectory that are located within the risk zone to the total number of discrete points of the trajectory; and computing a product of the ratio and the particular distance, thereby computing a cross length of the risk zone.

[0014] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, computing the risk value for the candidate SLZ comprises: computing a risk zone risk value for a respective risk zone of the one or more risk zones, the risk zone risk value for the risk zone being a product of a cross length of the risk zone and a risk weight factor for a risk category of the risk zone; and summing the risk zone risk values to compute the risk value for the candidate SLZ.

[0015] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the sequence is executed to operate the UAV to reach the selected one of the candidate SLZs along the trajectory, and with the updated current location, the method further comprises: generating or receiving an updated risk map for the geographic area in which the UAV is operating, the updated risk map comprising risk zones of respective updated risk categories with respective updated risk weight factors; computing an updated minimum risk value and an updated flight termination risk value based on the respective updated risk weight factors; and interrupting the sequence to cause the UAV to immediately land at the updated current location when the updated minimum risk value is greater than the updated flight termination risk value.

[0016] In some example implementations of the method of any of the preceding example implementations, or any combination of the preceding example implementations, the sequence is executed to operate the UAV to reach the selected one of the candidate SLZs along the trajectory when the minimum risk value is less than or equal to the flight termination risk value, and to cause the UAV to immediately land at the current location when the minimum risk value is greater than the flight termination risk value.

[0017] In some example implementations of the method of any of the preceding example implementations, or any combination of any of the preceding example implementations, the sequence is executed to operate the UAV to reach the selected one of the candidate SLZs along the trajectory, and to utilize the updated current location along the trajectory, the method further comprising: calculating an updated lowest risk value and an updated flight termination risk value; and when the updated lowest risk value is greater than the updated flight termination risk value, interrupting the sequence to cause the UAV to immediately land at the updated current location.

[0018] In some example implementations of the method of any of the preceding example implementations, or any combination of any of the preceding example implementations, the sequence is executed to operate the UAV to reach the selected one of the candidate SLZs along the trajectory, and to utilize the updated current location along the trajectory, the method further comprising: determining updated candidate SLZs within the updated estimated current range of the UAV from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs; generating updated trajectories for the UAV to land in the respective updated candidate SLZs; calculating updated risk values and an updated flight termination risk value, the lowest of the updated risk values being associated with an updated trajectory from the updated current location to the selected one of the updated candidate SLZs; performing a comparison of the lowest updated risk value and the updated flight termination risk value; and based on the comparison, executing an updated sequence to operate the UAV to reach the selected one of the updated candidate SLZs along the updated trajectory, or to cause the UAV to immediately land at the updated current location.

[0019] Some example implementations provide an apparatus for causing a drone (UAV) to perform an emergency landing procedure, the apparatus comprising: a memory configured to store computer-readable program code; and a processing circuit configured to access the memory and execute the computer-readable program code to cause the apparatus to perform at least the method of any of the preceding example implementations, or any combination of any of the preceding example implementations.

[0020] Some example implementations provide a computer-readable storage medium for causing a drone (UAV) to perform an emergency landing procedure, the computer-readable storage medium being non-transitory and storing computer-readable program code that, in response to execution by a processing circuit, causes the apparatus to perform at least the method of any of the preceding example implementations, or any combination of any of the preceding example implementations.

[0021] These and other features, aspects, and advantages of the present disclosure will become evident to those skilled in the art from a reading of the following detailed description, together with the accompanying drawings. The present disclosure includes any combination of two, three, four, or more of the features or elements set forth in the disclosure, whether explicitly described or not, in any of the described example implementations. The present disclosure is intended to be read altogether in its entirety including the claims, and any separable feature or element of the present disclosure should be considered combinable with any other feature or element of the present disclosure, unless the context of the disclosure clearly dictates otherwise.

[0022] It will therefore be appreciated that this summary is merely intended to summarize some example implementations to provide a basic understanding of some aspects of the present disclosure. It will therefore be appreciated that the above-described example implementations are merely examples and should not be construed as narrowing the scope or spirit of the present disclosure in any way. Other example implementations, aspects, and advantages will become apparent from a detailed description, taken in connection with the accompanying drawings, which illustrate by way of example some principles of the described example implementations. BRIEF DESCRIPTION OF DRAWINGS

[0023] Having generally described an example implementation of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, wherein:

[0024] Figure 1A illustrating a system including a drone (UAV) according to example implementations of the present disclosure;

[0025] Figure 1B illustrating a UAV with a trajectory to a corresponding safe landing zone according to example implementations of the present disclosure; Figure 1A

[0026] Figure 2 illustrating a portion of a risk map with multiple risk zones according to example implementations of the present disclosure;

[0027] Figure 3A , Figure 3B , Figure 3C and Figure 3D are flowcharts illustrating various steps in a method of performing an emergency landing procedure for a UAV according to example implementations of the present disclosure;

[0028] Figure 4A and Figure 4B are flowcharts illustrating various steps in a method of performing an emergency landing procedure for a UAV according to more specific example implementations of the present disclosure;

[0029] Figure 5 illustrating an apparatus according to some example implementations of the present disclosure. DETAILED DESCRIPTION ​

[0030] Some implementations of the disclosure will now be described more fully with reference to the accompanying drawings, in which some, and not all, implementations of the disclosure are shown. Indeed, various implementations of the disclosure can be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these example implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. For example, unless otherwise indicated, a reference to something being "first", "second", etc. should not be construed as indicating a particular order. Also, a reference to something being "on" another should not be construed as being directly on, unless otherwise indicated. Similarly, a reference to something being "under" another should not be construed as being directly under, unless otherwise indicated. Similarly, a reference to something being "left" of another should not be construed as being directly left of, unless otherwise indicated. Similarly, a reference to something being "right" of another should not be construed as being directly right of, unless otherwise indicated. Like reference numerals refer to like elements throughout.

[0031] Example implementations of the disclosure relate to unmanned aerial vehicles (UAVs), and in particular, to data-driven, risk-minimizing route finding and landing of a UAV in an emergency scenario. Some example implementations of the disclosure employ discretized trajectories to a user-defined safe landing zone (SLZ) and selected risk weighting factors to compute a risk value based on a risk map of an operating area of the UAV. As described herein, an SLZ is a landing zone (i.e., an area in which a UAV can land) that has been designated as safe (low risk) in the event of an emergency scenario. Computing a risk value can allow for comparison between multiple mission abort options to determine the most desirable response to a particular unexpected condition.

[0032] Figure 1A A system according to example implementations of the disclosure is shown. The system can include any of several different subsystems (individual systems) for performing one or more functions or operations. Although shown as part of the system, it should be understood that any one or more of the subsystems can function or operate as a standalone system. It should also be understood that the system can include Figure 1A one or more additional or alternative subsystems than those shown.

[0033] As Figure 1A In some examples, as shown, the system 100 includes an unmanned aerial system (UAS) 101 having a UAV 110 and a ground control station (GCS) 130 that can remotely control the UAV. In this regard, the UAV and the GCS can communicate via a communication link. Additionally, the UAS includes a device 120 that can be located on the UAV or at the GCS. Alternatively, in some examples, a first device can be located on the UAV and a second device can be located at the GCS.

[0034] According to example implementations of the present disclosure, the device 120 is configured to cause the UAV 110 to perform an emergency landing procedure. In this regard, in some examples, the device is configured to determine candidate SLZs 190 within an estimated current range of the UAV from a current location 112 of the UAV, as shown in FIG. 1. In these examples, the device is configured to generate a trajectory 170 for the UAV to land in a respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ. Figure 1B

[0035] In some examples, the trajectory 170 is or includes one or more straight lines. However, in other examples, the trajectory can be a non-straight or indirect trajectory. In this regard, one or more trajectories can be generated with an algorithm that takes into account internal and external factors such as terrain / landscape, obstacles that the UAV 110 should avoid, current wind direction and speed compared to the performance of the UAV, and the current range of the UAV estimated based on its current power level (power required to reach the SLZ following the generated trajectory). Examples of suitable algorithms include A-star, Voronoi diagrams, and Rapidly-exploring Random Trees.

[0036] The device 120 is configured to calculate a risk value quantifying third-party risk associated with operation of the UAV 110 along the respective trajectory 170 to the respective candidate SLZ 190. Here, the lowest risk value is associated with the trajectory from the current location 112 to the selected one candidate SLZ. The device is also configured to calculate a flight termination risk value quantifying third-party risk associated with causing the UAV to immediately land at the current location.

[0037] The device 120 is configured to perform a comparison of the lowest risk value and the flight termination risk value. And based on the comparison, the device is configured to perform a sequence to operate the UAV 110 along the trajectory to the selected one candidate SLZ 190, or to cause the UAV to immediately land at the current location 112. In some examples where the UAV 110 includes the device 120, the device is configured to autonomously perform the sequence without input from the GCS 130. In other examples where the device is included in the GCS, the device is configured to perform the sequence by remotely controlling the UAV from the GCS.

[0038] In some examples, the device 120 is also configured to generate or receive a risk map of a geographic region in which the UAV 110 operates. The risk map includes risk zones of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV 110 in the risk zones. In these examples, the trajectory 170 intersects a plurality of the risk zones, and the risk value is calculated based on the respective risk weight factors.

[0039] ​Figure 2 A portion of a risk map 200 according to an example implementation of the present disclosure is shown. The risk map 200 includes risk zones 220 (also referred to as risk zone polygons), which can be visually distinguished by various means such as color, pattern, shape, etc. In the example shown, the risk map includes risk zones 220A, 220B, 220C, and 220D (each labeled) of respective risk categories with respective risk weight factors.

[0040] In some further examples in which the trajectory 170 is or includes a straight line, for a candidate SLZ 190, the device 120 is configured to interpolate the straight line from the current location 112 to the candidate SLZ, thereby generating a trajectory to the candidate SLZ. In some of these examples, the device is configured to separate the trajectory into segments at intersection points with one or more risk zones 220 (shown in FIG. 17 as segments 170A and 170B intersecting with risk zones 220C and 220D, respectively), and to compute a risk value for the candidate SLZ from the segments and the risk weight factors of the one or more risk zones. This can be achieved by interpolation of the two-dimensional straight line segment between the current location of the UAV 110 and the SLZ through discretization of the trajectory. The risk value can then be computed from the intersection segments and the risk weight factors using a cost function. Figure 2

[0041] In some further examples, the straight line of the trajectory 170 is of a particular distance and includes a total number of discrete points over the particular distance. In these examples, the separation of the trajectory includes, for each of the one or more risk zones 220, the device 120 being configured to determine a ratio of a number of the discrete points of the trajectory that lie within the risk zone to the total number of discrete points of the trajectory. The device is then configured to compute a product of the ratio and the particular distance, thereby computing a length of intersection of the risk zone.

[0042] In some further examples, the device 120 is configured to compute a risk zone risk value for respective ones of the one or more risk zones 220. In these examples, the risk zone risk value for a risk zone is a product of a length of intersection of the risk zone and a risk weight factor of a risk category of the risk zone. In these further examples, the device 120 is configured to sum the risk zone risk values to compute a risk value for the candidate SLZ 190.

[0043] ​As described above, in some examples, calculation of the risk value associated with each SLZ 190 includes separating the trajectory 170 into segments (e.g., segments 170A and 170B) that intersect the corresponding risk zone 220. This can be achieved by discretizing the trajectory by interpolating two-dimensional straight line segments between the current position of the UAV 110 and the SLZ. In this regard, the trajectory 170 may include a plurality of discrete points along its length, and the risk zone 220 may be formed by edges that are connected at vertices to form a closed polygonal shape. In some examples, based on a crossing number algorithm such as Franklin's PNPOLY algorithm, the device 120 may determine whether a point on the trajectory is located within a given risk zone 220 defined by its vertices. More specifically, the proportion of discrete points on the trajectory that are located within the risk zone relative to all discrete points on the trajectory may be calculated as follows:

[0044]

[0045] In formula 1, f k,j is the proportion of trajectories within the jth risk zone to the kth SLZ, p k,j is the number of discrete points on the trajectory that lie within the risk zone, q k is the total number of discrete points on the trajectory.

[0046] The device 120 may calculate the ratio f k,j and a specific distance s from the current position 112 to the straight line SLZ 190 k The product of , and thus the intersection length of the j-th risk zone for the k-th SLZ is calculated, for example, according to the following formula:

[0047] s k,j =f k,j ·s k (Formula 2)

[0048] where s k,j is the crossing length of the j-th risk zone for the k-th SLZ.

[0049] The device 120 may also use the intersection length s of the risk zone k The risk zone risk value of the risk zone 220 is calculated by multiplying (calculating as a product) the cost function with the risk weight factor of the risk category of the j-th risk zone. This operation can be repeated for other risk zones crossed by the trajectory 170 to the k-th SLZ to calculate the corresponding risk zone risk values ​​of the risk zones, which can then be summed to calculate the risk value of the SLZ.

[0050] In some examples, the risk areas intersecting the trajectory 170 may be grouped by risk category, and the intersection length is calculated for each risk category. More specifically, for example, according to the following formula, i The cross length S of the kth SLZ (among l candidate SLZs)k,i can be calculated as the intersection length s of those risk zones k,j sum:

[0051]

[0052] The cross length S of the i-th risk category can be calculated k,i Its corresponding risk weight factor W i This operation can be repeated for risk areas of other risk categories crossed by the trajectory 170 to the kth SLZ to calculate the corresponding risk values ​​of the risk categories, which can then be summed to calculate the risk value R of the kth SLZ for example for n risk categories according to the following formula: k :

[0053]

[0054] The flight termination risk value can be determined in a similar manner as described above, but recognizing that the UAV 110 may be located within the risk zone 220 at its current location 112, rather than following a trajectory 170 that crosses the risk zone. In some examples, the flight termination risk value then corresponds to a risk weighting factor that quantifies the third-party risk associated with the operation of the UAV in the risk zone at its current location. In some example implementations, a vision-based system can be used in conjunction with or in place of the risk weighting factor.

[0055] In some examples, device 120 is configured to perform calculation of the minimum risk value R according to the following formula: k With flight termination risk R at current position 112 FT Comparison between:

[0056]

[0057] Based on this comparison, the device is caused to execute the sequence with the lowest risk value. Less than or equal to the flight termination risk value R FT The apparatus may be configured to operate the UAV 110 along the trajectory 170 to the selected one of the candidate SLZs 190 and immediately land the UAV at the current location when the minimum risk value is greater than the flight termination risk value. The apparatus may be configured to identify when the minimum risk value and the flight termination risk value are equal and, in response, execute a sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs.

[0058] In some examples of executing a sequence to operate the UAV 110 along the trajectory 170 to a selected one of the candidate SLZs 190, and utilizing the updated current position 112 along the trajectory, the device 120 is further configured to calculate an updated minimum risk value (e.g., ) and updated flight termination risk values ​​(e.g., RFT ) and when the updated minimum risk value is greater than the updated flight termination risk value, the device is configured to interrupt the sequence to cause the UAV to land immediately at the updated current location.

[0059] Similarly, in some examples, the device 120 is also configured to generate or receive an updated risk map of the geographic area in which the UAV 110 is operating. The updated risk map includes risk zones 220 of respective updated risk categories with respective updated risk weight factors. In this regard, one or more of the respective updated risk categories and the respective updated risk weight factors can be different from the respective risk categories and the respective risk weight factors of the (earlier) risk map 200. In these examples, the device is configured to compute an updated minimum risk value and an updated flight termination risk value based on the respective updated risk weight factors. The device is then configured to, when the updated minimum risk value is greater than the updated flight termination risk value, interrupt the sequence to cause the UAV to land immediately at the updated current location.

[0060] Additionally or alternatively, in some examples in which the sequence is executed to operate the UAV 110 along the trajectory 170 to the selected one of the candidate SLZs 190, the device 120 is also configured to determine updated candidate SLZs within the updated estimated current range of the UAV from the updated current location 112. Here, the updated candidate SLZs include the selected one of the candidate SLZs.

[0061] In these examples, the device 120 is configured to generate an updated trajectory 170 for the UAV 110 to land in the respective updated candidate SLZ 190 and to compute an updated risk value (e.g., R k ) and an updated flight termination risk value R FT . Similar to earlier, the minimum updated risk value (e.g., ) is associated with the updated trajectory from the updated current location 112 to the selected one of the updated candidate SLZs. The device is configured to perform a comparison of the minimum updated risk value and the updated flight termination risk value. And based on the comparison, the device is configured to execute an updated sequence to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs or to cause the UAV to land immediately at the updated current location.

[0062] Figure 3A 、 Figure 3B 、 Figure 3C and Figure 3D are flow diagrams illustrating various steps in a method 300 of performing an emergency landing procedure for a UAV 110 in accordance with example implementations of the present disclosure. As Figure 3AAs shown at block 302, the method includes determining candidate SLZs 190 that are within an estimated current range of the UAV from the current location 112. As shown at block 304, the method includes generating a trajectory 170 for causing the UAV to land in a respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ.

[0063] As shown at block 308, the method 300 includes calculating a risk value quantifying third-party risk associated with operation of the UAV 110 along the respective trajectory 170 to the respective candidate SLZ 190, the lowest risk value being associated with the trajectory to the selected one of the candidate SLZs from the current location.

[0064] In some examples, the method 300 further includes generating or receiving a risk map 200 of a geographic region in which the UAV 110 operates, as shown at block 306. The risk map includes risk zones 220 of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV in the risk zones. In these examples, the trajectory 170 intersects a plurality of the risk zones, and the risk value is calculated at block 306 based on the respective risk weight factors.

[0065] As shown at block 310, the method 300 includes calculating a flight termination risk value quantifying third-party risk associated with causing the UAV to land immediately at the current location 112.

[0066] The method 300 further includes performing a comparison of the lowest risk value and the flight termination risk value, as shown at block 312. Based on the comparison, the method includes performing a sequence to operate the UAV 110 along the trajectory 170 to the selected one of the candidate SLZs 190 or to cause the UAV to land immediately at the current location 112, as shown at block 314.

[0067] In some examples, generating the trajectory 170 at block 304 includes, for a candidate SLZ 190, interpolating a straight line from the current location 112 to the candidate SLZ, thereby generating the trajectory to the candidate SLZ. In some of these examples that also include generating or receiving the risk map 200 at block 306, calculating the risk value at block 308 includes, for the trajectory, separating the trajectory into segments 170A, 170B at intersection points with one or more risk zones 220, as shown at block 308A. The risk value for the candidate SLZ is then calculated from the segments and risk weight factors of the one or more risk zones, as shown at block 308B. Figure 3B

[0068] ​In some further examples, the straight line is of a particular distance and includes a total number of discrete points over the particular distance. In these examples, separating the trajectory 170 at block 308A includes, for each risk zone 220 of the one or more risk zones, determining a ratio of a number of discrete points on the trajectory that are located within the risk zone to the total number of discrete points of the trajectory, as indicated by block 308A1. A product of the ratio and the particular distance is then computed, thereby computing a cross length of the risk zone, as indicated by block 308A2.

[0069] Similarly, in some further examples, computing the risk value of the candidate SLZ 190 at block 308B includes computing a risk zone risk value for a respective risk zone of the one or more risk zones 220, as indicated by block 308B1. Here, the risk zone risk value for a risk zone is a product of the cross length of the risk zone and the risk weight factor for the risk category of the risk zone. The risk zone risk values are then summed to compute the risk value of the candidate SLZ, as indicated by block 308B2.

[0070] In some examples in which the sequence is executed to operate the UAV 110 along the trajectory 170 to the selected one of the candidate SLZs 190, and with the updated current location 112, the method 300 further includes computing an updated lowest risk value and an updated flight termination risk value, as indicated by block 318. In these examples, the method further includes interrupting the sequence to cause the UAV to land immediately at the updated current location when the updated lowest risk value is greater than the updated flight termination risk value, as indicated by block 320. Further, in some examples, the method includes generating or receiving an updated risk map 200 for the geographic region in which the UAV 110 is operating, as indicated by block 316. The updated risk map includes risk zones 220 of respective updated risk categories with respective updated risk weight factors. In these further examples, the updated lowest risk value and the updated flight termination risk value are computed based on the respective updated risk weight factors at block 318. Figure 3C

[0071] Additionally or alternatively, in some examples, the method 300 further includes determining updated candidate SLZs 190 that are within an updated estimated current range of the UAV 110 from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs, as indicated by block 322. In these examples, the sequence is executed to operate the UAV 110 along the trajectory 170 to one of the updated candidate SLZs 190, as indicated by block 324. Figure 3D ​The method includes generating, at block 324, updated trajectories 170 for causing the UAV to land in the respective updated candidate SLZs, and computing updated risk values and updated flight termination risk values, the lowest updated risk value being associated with the updated trajectory from the updated current location to the selected one of the updated candidate SLZs, as shown at block 326. The method includes performing a comparison of the lowest updated risk value and the updated flight termination risk value, as shown at block 328. Based on the comparison, an updated sequence is executed to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs, or to cause the UAV to land immediately at the updated current location, as shown at block 330.

[0072] Returning to Figure 1A In some example implementations, the emergency landing procedure can be considered as part of an emergency management system, which can include a pre-flight phase and an in-flight phase. During the pre-flight phase, data related to emergency events can be gathered, and data sets can be prepared for use during the in-flight phase. In some of these examples, the system 100 can also include a data gathering server 140 configured to gather data related to emergency events from various resources, such as one or more databases 160, via the network 150, which can be configured to prepare data sets for use during the in-flight phase. A first data set can be a risk map 200 for an operating (flight) area of the UAV 110, and the risk map can include data gathered from the databases 160. Risk assessment (e.g., a specific operating risk assessment (SORA)) can be performed using automated or semi-automated processing. From this processing, a risk map including risk zones 220 can be generated for the operating area of the UAV. In some examples, the risk map can also include restricted flight zones for the operating area.

[0073] A second data set can include data defining SLZs 190, which can be manually or automatically assigned in third party low risk areas. The first, second, and any other relevant data sets can be uploaded to a flight computer of the UAV 110 so that the data is available even in the event of a loss of communication link between the UAV and the GCS 130.

[0074] During the in-flight phase, internal system health of the UAV 110, as well as external factors such as weather, can be continuously monitored by various sensors on the UAV (compared to system performance limits of the UAV). Upon detection of an emergency event, the event can first be analyzed in depth by assessing the affected subsystems of the UAS 101 and the severity of the situation. Then, an appropriate action can be decided. If there is no communication link between the UAV and the GCS 130, the decision can be made autonomously by the UAV, or the decision can utilize input from a remote pilot-in-command (PiC). Other situations can rely on the PiC to have full control of the UAV, operating in manual mode.

[0075] Figure 4A and Figure 4B A flowchart of a method of executing an emergency landing procedure for a UAV is shown according to a more specific example implementation of an emergency management system. While the UAV is in flight, an emergency event can be detected and announced (e.g., an event report) to one or more stakeholders upon detection, as shown in blocks 401 and 402. The GCS 130 can act as an interface to the PiC and inform the PiC of relevant information. Air traffic control (ATC) and other airspace users in the vicinity of the UAV 110 can be informed in the event that the emergency event affects the airworthiness of the UAV. The ATC can be contacted either directly through a link with the UAV or through the GCS 130. The emergency event can also be transmitted to other aircraft in the vicinity of the UAV via ADS-B or other broadcast systems. Figure 4A

[0076] The detection of the emergency event can involve an assessment of two main capabilities of the UAS 101: the navigation capability (e.g., a geo-positioning and time system such as GPS) of the UAV 110 and the connection of the UAV to the GCS 130 via a communication link, as shown in blocks 404, 406, and 408. The navigation capability (NAVCAP) can be checked in block 404 to determine whether it is fully functional, and the status of the communication link (which can be referred to as a command and control link or C2 link) can also be tested. Both checks can result in a positive (“running” in block 406) or negative (“not running” in block 408) outcome according to platform-specific parameters and thresholds.

[0077] After performing both checks, the system 100 can be determined to be in one of four states, which are related to possible actions that can be taken in response to the emergency event and the determined state, as shown in blocks 414 (CTL), 416 (continue mission), 418 (manual mode), and 420 (FT). Before continuing, the system 100 can first enter a temporary hold mode for a specified amount of time and attempt to restore the communication link and / or the navigation capability that stopped running, in some examples, when either or both of the communication link or the navigation capability stopped running. If successful, the system can return to the state where both are running.

[0078] In some examples, a nested unexpected condition can affect both the communication link and the navigation capability at the same time. As shown in Figure 4A and Table I below, the result of the decision process can be one of four actions: an emergency landing procedure, which can be fully automatic or semi-automatic; a command to continue the mission (selected by the PiC for smaller unexpected conditions); a manual mode (the PiC takes over control of the UAV 110); and a flight termination (FT).

[0079] ​Table I: System States for Decision Making Based on Emergency Events

[0080]

[0081] For a system state 1 example where the navigation capability is operational and the communication link is not operational, the appropriate action is an emergency landing procedure. The emergency landing procedure can result in a controlled landing (sometimes referred to as an immediate landing or flight termination) at one of the defined SLZs 190, or somewhere between the current location 112 where the emergency landing procedure was initiated and one of the SLZs, as described herein.

[0082] In some example implementations, the decision process incorporates a human autonomous teaming (HAT) approach that includes input from the PiC for various functions and / or decisions (e.g., when the communication link is operational, system states 2 and 3), as shown in block 410. When the navigation capability of the UAV 110 is operational (e.g., system state 2), the system can work with the PiC to resolve the emergency event. Consistent with block 410, the PiC can be provided a choice between taking over manual control of the UAV 110 (manual mode), continuing the mission in the case of a minor contingency, or initiating an emergency landing (CTL) procedure, as shown in blocks 414-418.

[0083] For a system state 3 example, when the UAS 101 is unable to navigate, the UAV 110 can attempt to maintain its current location using remaining navigation systems such as inertial and vision-based navigation, as shown in block 412, and can then switch to a manual flight mode with PiC control of the UAV, as shown in block 418. Maintaining the location can include a steady mode of maintaining the UAV’s altitude and position as long as no input is received from the PiC. This can allow the PiC to use camera feeds from the UAV, as well as other available means of gaining situational awareness (e.g., interactive maps or sonar data) to attempt a safe landing (consistent with the “manual mode” shown in block 418).

[0084] When both the navigation capability and the communication link are not operational (e.g., a system state 4 example), the emergency event can pose a significant threat to operational safety. Under system state 4, the remaining flight time of the UAV 110 can be limited to a minimum to minimize the risk in the air. Consistent with blocks 404, 408, and 420, the UAS 101 can immediately enter a flight termination mode, initiating a landing procedure to land the UAV at its current location 112, and triggering a flight termination system in the event that conditions worsen during the landing.

[0085] The emergency landing procedure can be initiated by the emergency management system in order to safely reach and land at one of the predefined SLZs 190 or the takeoff location, abandoning the original mission. Figure 4B An example of a system state 4 is shown from Figure 4Athe procedure that continues from block 414.

[0086] As shown in Table I and Figure 4B The emergency landing procedure can be initiated by the emergency management system when the navigation capability is functional (“running”). The communication link can or can not be functional (e.g., system states 1 and 2). Figure 4B The emergency landing procedure is shown with two branches (full- and semi-automatic modes) that exhibit different levels of automation to calculate risk, as shown in block 426. The branches can occur after the risk value is calculated.

[0087] Figure 4B The full-automatic mode depicted on the left side of Figure 4B The semi-automatic mode shown on the right side of

[0088] In an example using the full-automatic mode, the SLZ 190 with the lowest risk value is identified, and if the risk is acceptable (e.g., less than or equal to the flight termination risk value), the UAV 110 can fly toward and land at that SLZ, as shown in blocks 428 (compare SLZ and FT risk), 430 (select best SLZ), 432 (advance toward SLZ until SLZ is reached), and 446A (land at SLZ). If the risk is not acceptable (e.g., greater than the flight termination risk value), flight termination can be triggered, as shown in block 448A. For the semi-automatic case, the process can include increased complexity due to the inclusion of the PiC in the decision making as part of the HAT method in the emergency management system, and the functional communication link can allow continuous risk data updates, as shown in blocks 434 (display risk, trajectory and factors, options), 436 (PiC selects SLZ), 438 (PiC modifies trajectory), 440 (advance toward SLZ until SLZ is reached), 442 (update risk data), 444 (recompute SLZ and FT risk), and 446B (land at SLZ).

[0089] In some example implementations, the emergency landing procedure filters (e.g., pre-filters) the available SLZs 190 from a database in database 421, which may also include aeronautical data (e.g., data describing terrain, obstacles, and airspace) and a risk map 200 with risk weighting factors, as shown in box 422. The filtering can be based on a reachability assessment that takes into account the direct distance from the UAV 110 to the SLZ and the current range of the UAV based on its estimated residual power level. In a fully automatic mode, for computationally intensive processing tasks involving a potentially large number of SLZs to be considered, the assessment can utilize simple calculations to avoid consuming the residual power level of the UAV. The filtering is to reduce the number of SLZs prepared for the more computationally intensive steps following the reachability assessment. If the total number of SLZs is small (e.g., 10 or less), the reachability assessment can be skipped.

[0090] In the example of using semi-automatic mode, most of the processing can be performed in a similar manner to the fully automatic mode. However, the PiC is able to provide input or override the proposed decision. The ergonomic user interface allows the PiC to view relevant data and provide input for decisions as part of the HAT method.

[0091] In semi-automatic mode, the SLZs 190 that were filtered out at block 422 are still available and displayed to the PiC upon request. As shown in block 424, the trajectory 170 is generated in the same manner as in the fully automatic mode, and the trajectory 170 may use aviation data from the database 421, such as data describing terrain, obstacles, and airspace. Additionally, the PiC has the option of adjusting the risk weighting factors (not shown). The resulting risk values ​​associated with each SLZ 190 are displayed together with the trajectory 170 (e.g., the risk values ​​may be displayed in an ordered, color-coded list, and the trajectory may be displayed on a risk map 200). Figure 2 This visual feedback is consistently provided to the PiC.

[0092] As shown in block 438, the PiC may modify a particular trajectory 170 (e.g., by moving waypoints forming the trajectory and / or by defining additional waypoint parameters). Consistent with block 440, if the PiC does not confirm the selected SLZ 190 and trajectory within a specified time window and does not perform any action, an automatic timeout may be used to confirm the selection of the best SLZ (the SLZ with the lowest risk value) and calculated trajectory.

[0093] Once the trajectory 170 and SLZ 190 are confirmed by the PiC or through an automatic timeout, the risk of the trajectory to the SLZ 190 and the current flight termination risk can be continuously recalculated by updating the risk map, as shown in blocks 442 and 444. If it is safer to terminate flight at any point along the trajectory than to continue to fly to the SLZ, as indicated when the updated minimum risk value is greater than the updated flight termination risk value, then flight termination can be triggered as shown in block 448B. If not, the UAV 110 can continue to fly to the SLZ as shown in block 446B.

[0094] In some example implementations, data that is susceptible to rapid change (e.g., the number of people in an area, real-time traffic conditions, etc.) can be continuously updated throughout the flight, as long as the communication link is functioning. The updating of the data can be done by the GCS 130, in order to prevent the processing, storage, and bandwidth requirements of the computer and bus on the UAV 110 from being used for additional computationally intensive tasks. The updating can include the GCS retrieving aggregated data from the server 140. The retrieved aggregated data can be processed into an update package, which is then transmitted to the UAV computer responsible for replacing old data in the risk map 200 with the updated data.

[0095] According to example implementations of the disclosure, the device 120 can be implemented by various means. The means for implementing the device can include hardware (alone or in combination with one or more computer programs from a computer-readable storage medium). In some examples, one or more devices can be configured to function as or said to implement the device shown and described herein. In examples involving more than one device, the various devices can be connected to or said to communicate with each other in a number of different ways (e.g., directly or indirectly via a wired or wireless network, etc.).

[0096] Figure 5 A device 500 (which can correspond to the device 120) according to some example implementations of the disclosure is shown. Generally, the devices of example implementations of the disclosure can be included in or embodied by one or more fixed or portable electronic apparatuses. Examples of suitable electronic apparatuses include smartphones, tablet computers, laptop computers, desktop computers, workstation computers, server computers, etc. The device can include one or more of a number of components such as a processing circuit 502 (e.g., a processor unit) connected to a memory 504 (e.g., a storage device).

[0097] The processing circuit 502 can include one or more processors (alone or in combination with one or more memories). The processing circuit is generally any computer hardware, capable of processing, such as for example, data, computer programs, and / or other suitable electronic information. The processing circuit includes a collection of electronic circuits, some of which can be packaged together into integrated circuits or multiple interconnected integrated circuits (integrated circuits are sometimes more commonly referred to as "chips"). The processing circuit can be configured to execute a computer program that can be stored on the processing circuit or said to be stored in the memory 504 (of the same or another device).

[0098] According to particular implementations, the processing circuit 502 can be a plurality of processors, a multi-core processor, or some other type of processor. Additionally, the processing circuit can be implemented with a plurality of heterogeneous processor systems, where a main processor exists on a single chip with one or more secondary processors. As another example illustration, the processing circuit can be a symmetric multi-processor system containing a plurality of processors of the same type. In another example, the processing circuit can be embodied as or include one or more ASICs, FPGAs, etc. Thus, although the processing circuit is capable of executing a computer program to perform one or more functions, various example processing circuits are capable of performing the one or more functions without the aid of a computer program. In either case, the processing circuit can be suitably programmed to perform the functions or operations according to example implementations of the present disclosure.

[0099] The memory 504 is generally any computer hardware capable of storing, in a temporary and / or persistent manner, for example, data, computer programs (e.g., computer readable program code 506), and / or other suitable information. The memory can include volatile and / or nonvolatile memory, and can be fixed or removable. Examples of suitable memory include random access memory (RAM), read only memory (ROM), hard drives, flash memory, thumb drives, removable computer disks, optical discs, magnetic tape, or some combination thereof. The optical discs can include compact discs - read only memory (CD-ROM), compact discs - read / write (CD-R / W), DVDs, etc. In various cases, the memory can be referred to as a computer readable storage medium. A computer readable storage medium is a non-transitory device that can store information and is distinguishable from a computer readable transmission medium that can carry information from one location to another, such as an electronic, temporal signal. A computer readable medium as described herein can generally represent a computer readable storage medium or a computer readable transmission medium.

[0100] In addition to the memory 504, the processing circuitry 502 can be connected to one or more interfaces for the display, transmission, and / or reception of information. The interfaces can include a communication interface 508 (e.g., a communication unit) and / or one or more user interfaces. The communication interface can be configured to transmit and / or receive information, e.g., to and / or from other devices, networks, etc. The communication interface can be configured to transmit and / or receive information over physical (wired) and / or wireless communication links. Examples of suitable communication interfaces include network interface controllers (NICs), wireless NICs (WNICs), etc.

[0101] The user interface can include a display 510 and / or one or more user input interfaces 512 (e.g., input / output units). The display can be configured to present or say information to a user, suitable examples of which include liquid crystal displays (LCDs), light emitting diode displays (LEDs), plasma display panels (PDPs), etc. The user input interfaces can be wired or wireless and can be configured to receive information into the device from a user for processing, storage, and / or display, for example. Suitable examples of user input interfaces include microphones, image or video capture devices, keyboards or keypads, joysticks, touch- sensitive surfaces (separate from or integrated into a touchscreen), biometric sensors, etc. The user interface can also include one or more interfaces for communication with peripherals such as printers, scanners, etc.

[0102] As described above, program code instructions can be stored in the memory and executed by processing circuitry programmed thereby to implement the functions of the systems, subsystems, tools, and their respective elements described herein. It will be understood that any suitable program code instructions can be loaded onto the computer or other programmable apparatus from a computer-readable storage medium to produce a particular machine, such that the particular machine becomes a means for implementing the functions specified herein. These program code instructions can also be stored in a computer-readable storage medium that can direct a computer, a processing circuitry, or other programmable apparatus to function in a particular manner, such that the particular machine or particular article of manufacture becomes a means for implementing the functions specified herein. The instructions stored in the computer-readable storage medium can produce an article of manufacture, where the article of manufacture becomes the means for implementing the functions specified herein. The program code instructions can be retrieved from the computer-readable storage medium and loaded into a computer, processing circuitry, or other programmable apparatus to configure the computer, processing circuitry, or other programmable apparatus to execute operations to be performed on or by the computer, processing circuitry, or other programmable apparatus.

[0103] Retrieval, loading, and execution of the program code instructions can be performed by a retrieval circuit, a loading circuit, and an execution circuit, each of which can be, for example, a processor or a portion of a processor, such as for example a processor core, that is configured to carry out the instructions. Retrieval, loading, and / or execution can be performed sequentially, in some example implementations, so that one instruction is retrieved, loaded, and executed at a time. In some example implementations, retrieval, loading, and / or execution can be performed in parallel, so that multiple instructions are retrieved, loaded, and / or executed together. Execution of the program code instructions can generate a computer-implemented process, such that the instructions carried out by the computer, the processing circuit, or other programmable device provide operations for implementing the functions described herein.

[0104] Execution of the instructions by the processing circuit, or storage of the instructions in the computer-readable storage medium, support combinations of operations for performing the specified functions. In this manner, the device 500 can include the processing circuit 502 and a computer-readable storage medium or memory 504 coupled to the processing circuit, wherein the processing circuit is configured to execute computer-readable program code 506 stored in the memory. It will also be appreciated that one or more functions and combinations of functions can be implemented by special purpose hardware-based computer systems which perform some or all of the procedures specified, or combinations of program code and special purpose hardware.

[0105] Further, the present disclosure includes examples according to the following clauses:

[0106] Clause 1. A device for causing a drone (UAV) to perform an emergency landing procedure, the device comprising: a memory configured to store computer-readable program code; and a processing circuit configured to access the memory and execute the computer-readable program code to cause the device to at least: determine candidate safe landing zones within an estimated current range of the UAV from a current location; generate, based on environmental and operational factors affecting flight of the UAV from the current location to respective candidate SLZs, a trajectory for causing the UAV to land in a respective candidate SLZ; calculate a risk value quantifying third party risk associated with operation of the UAV along the respective trajectory to the respective candidate SLZ, a lowest risk value being associated with a trajectory from the current location to a selected one of the candidate SLZs; calculate a flight termination risk value quantifying third party risk associated with the UAV immediately landing at the current location; perform a comparison of the lowest risk value and the flight termination risk value; and based on the comparison, perform a sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs, or to cause the UAV to immediately land at the current location.

[0107] Clause 2. The device of clause 1, wherein the processing circuit is further configured to cause the device, located on the UAV, to autonomously perform the sequence without input from a ground control station (GCS), wherein the GCS and the UAV are part of an unmanned aerial system.

[0108] Clause 3. The device of any of clauses 1-2, wherein the UAV is part of an unmanned aerial system, the unmanned aerial system further comprising a ground control station (GCS), the device is located at the GCS, and the device is caused to perform the sequence by remotely controlling the UAV from the GCS.

[0109] Clause 4. The device of any of clauses 1-3, wherein the processing circuitry is configured to execute the computer-readable program code to further cause the device to: generate or receive a risk map of a geographic area of operation of the UAV, the risk map comprising risk zones of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV in the risk zones, wherein the trajectory intersects a plurality of the risk zones, and compute a risk value based on the respective risk weight factors.

[0110] Clause 5. The device of clause 4, wherein the device being caused to generate the trajectory comprises, for a candidate SLZ, the device being caused to interpolate a straight line from the current location to the candidate SLZ, thereby generating the trajectory to the candidate SLZ, and wherein the device being caused to compute the risk value comprises, for the trajectory, the device being caused to: separate the trajectory into segments at intersection points with one or more risk zones; and compute a risk value for the candidate SLZ from the segments and risk weight factors of the one or more risk zones.

[0111] Clause 6. The device of any of clauses 4-5, wherein the straight line is of a particular distance and comprises a total number of discrete points over the particular distance, and the device being caused to separate the trajectory comprises, for each of the one or more risk zones, the device being caused to: determine a ratio of a number of the discrete points on the trajectory that are located within the risk zone to the total number of discrete points of the trajectory; and compute a product of the ratio and the particular distance, thereby computing a cross-length of the risk zone.

[0112] Clause 7. The device of any of clauses 4-6, wherein the device being caused to compute the risk value for the candidate SLZ comprises the device being caused to: compute a risk zone risk value for respective ones of the one or more risk zones, the risk zone risk value for a risk zone being a product of a cross-length of the risk zone and a risk weight factor of a risk category of the risk zone; and sum the risk zone risk values to compute the risk value for the candidate SLZ.

[0113] Clause 8. The device of clause 4, wherein the device is caused to execute the sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs, and with the updated current location, the processing circuitry is configured to execute the computer-readable program code to cause the device to further: generate or receive an updated risk map of the geographic area of UAV operations, the updated risk map including risk zones of respective updated risk categories with respective updated risk weight factors; compute an updated minimum risk value and an updated flight termination risk value based on the respective updated risk weight factors; and interrupt the sequence to cause the UAV to immediately land at the updated current location when the updated minimum risk value is greater than the updated flight termination risk value.

[0114] Clause 9. The device of any one of clauses 1-8, wherein the device is caused to execute the sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs when the minimum risk value is less than or equal to the flight termination risk value, and to cause the UAV to immediately land at the current location when the minimum risk value is greater than the flight termination risk value.

[0115] Clause 10. The device of any one of clauses 1-9, wherein the device is caused to execute the sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs, and with the updated current location, the processing circuitry is configured to execute the computer-readable program code to cause the device to further: compute an updated minimum risk value and an updated flight termination risk value; and interrupt the sequence to cause the UAV to immediately land at the updated current location when the updated minimum risk value is greater than the updated flight termination risk value.

[0116] Clause 11. The device of any one of clauses 1-10, wherein the device is caused to execute the sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs, and with the updated current location, the processing circuitry is configured to execute the computer-readable program code to cause the device to further: determine updated candidate SLZs within an updated estimated current range of the UAV from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs; generate an updated trajectory for causing the UAV to land in a respective updated candidate SLZ; compute updated risk values and an updated flight termination risk value, the lowest updated risk value being associated with the updated trajectory from the updated current location to the selected one of the updated candidate SLZs; perform a comparison of the lowest updated risk value and the updated flight termination risk value; and based on the comparison, perform an updated sequence to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs, or to cause the UAV to immediately land at the updated current location.

[0117] Clause 12. A method of performing an emergency landing procedure for an unmanned aerial vehicle (UAV), the method comprising: determining candidate safe landing zones (SLZs) within an estimated current range of the UAV from a current location; generating, for each respective candidate SLZ, a trajectory for landing the UAV in the respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ; calculating a risk value quantifying third-party risk associated with operation of the UAV along the respective trajectory to the respective candidate SLZ, a lowest risk value of the risk values being associated with a trajectory to a selected one of the candidate SLZs from the current location; calculating a flight termination risk value quantifying third-party risk associated with immediate landing of the UAV at the current location; performing a comparison of the lowest risk value and the flight termination risk value; and based on the comparison, performing a sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs or to cause the UAV to land immediately at the current location.

[0118] Clause 13. The method of clause 12, wherein the UAV is part of an unmanned aerial system further comprising a ground control station (GCS), the method being performed on the UAV and autonomously performing the sequence without input from the GCS.

[0119] Clause 14. The method of any one of clauses 12-13, wherein the UAV is part of an unmanned aerial system further comprising a ground control station (GCS), the method being performed at the GCS and performing the sequence by remotely controlling the UAV from the GCS.

[0120] Clause 15. The method of any one of clauses 12-14, further comprising: generating or receiving a risk map for a geographic region of operation of the UAV, the risk map comprising risk zones of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV in the risk zones, wherein the trajectory intersects a plurality of the risk zones, and the risk value is calculated based on the respective risk weight factors.

[0121] Clause 16. The method of clause 15, wherein the step of generating the trajectory comprises, for a candidate SLZ, interpolating a straight line from the current location to the candidate SLZ to thereby generate the trajectory to the candidate SLZ, and wherein the step of calculating the risk value comprises, for the trajectory: separating the trajectory into segments at intersection points with one or more risk zones; and calculating the risk value for the candidate SLZ from the segments and risk weight factors of the one or more risk zones.

[0122] Clause 17. The method of clause 16, wherein the straight line is a particular distance and comprises a total number of discrete points over the particular distance, and the step of separating the trajectories comprises, for each of the one or more risk zones: determining a ratio of a number of the discrete points on the trajectory that are located within the risk zone to the total number of discrete points of the trajectory; and calculating a product of the ratio and the particular distance, thereby calculating a cross length of the risk zone.

[0123] Clause 18. The method of any one of clauses 15 to 17, wherein the step of calculating the risk value for the candidate SLZ comprises: calculating a risk zone risk value for a respective risk zone of the one or more risk zones, the risk zone risk value for the risk zone being a product of the cross length of the risk zone and a risk weight factor for the risk category of the risk zone; and summing the risk zone risk values to calculate the risk value for the candidate SLZ.

[0124] Clause 19. The method of clause 15, wherein the sequence is executed to operate the UAV along the trajectory to the selected one of the candidate SLZs, and along the trajectory with an updated current location, the method further comprising: generating or receiving an updated risk map for the geographic area in which the UAV is operated, the updated risk map comprising risk zones of respective updated risk categories with respective updated risk weight factors; calculating an updated minimum risk value and an updated flight termination risk value based on the respective updated risk weight factors; and interrupting the sequence to cause the UAV to immediately land at the updated current location when the updated minimum risk value is greater than the updated flight termination risk value.

[0125] Clause 20. The method of any one of clauses 12 to 19, wherein the sequence is executed to operate the UAV along the trajectory to the selected one of the candidate SLZs when the minimum risk value is less than or equal to the flight termination risk value, and to cause the UAV to immediately land at the current location when the minimum risk value is greater than the flight termination risk value.

[0126] Clause 21. The method of any one of clauses 12 to 20, wherein the sequence is executed to operate the UAV along the trajectory to the selected one of the candidate SLZs, and along the trajectory with an updated current location, the method further comprising: calculating an updated minimum risk value and an updated flight termination risk value; and interrupting the sequence to cause the UAV to immediately land at the updated current location when the updated minimum risk value is greater than the updated flight termination risk value.

[0127] Clause 22. The method of any of clauses 12-21, wherein the sequence is executed to operate the UAV along a trajectory to the selected one of the candidate SLZs, and with the updated current location, the method further comprising: determining updated candidate SLZs within an updated estimated current range of the UAV from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs; generating updated trajectories for causing the UAV to land in the respective updated candidate SLZs; calculating updated risk values and updated flight termination risk values, a lowest updated risk value associated with an updated trajectory from the updated current location to the selected one of the updated candidate SLZs; performing a comparison of the lowest updated risk value and the updated flight termination risk value; and based on the comparison, executing an updated sequence to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs, or causing the UAV to land immediately at the updated current location.

[0128] Many modifications and other implementations will occur to those of ordinary skill in the art upon reading the description and viewing the related drawings that present the disclosure. Therefore, it is to be understood that the disclosure is not to be limited to the particular implementations disclosed, but is intended to cover modifications and other implementations within the scope of the claims. Further, although example implementations are described above in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions can be provided by alternative implementations without departing from the scope of the claims. In this regard, for example, an element specified in the context of a particular example implementation can be implemented in a different example implementation to yield a different result. Each of the elements and / or functions described herein can also be implemented in a different example implementation and / or to result in a different result. Further, it should be appreciated that functions might be embodied in whole or in part in hardware, firmware, software, and / or any combination thereof.

Claims

1. A device (120, 500) for causing an unmanned aerial vehicle, UAV, (110) to perform an emergency landing procedure, the device comprising: a memory (504) configured to store computer-readable program code (506); and a processing circuit (502) configured to access the memory and execute the computer-readable program code to cause the device at least to: determine (302) candidate safe landing zones, SLZs, (190) within an estimated current range of the UAV from a current location (112); generate (304) a trajectory (170) for causing the UAV to land in a respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ; for a candidate SLZ (190), interpolate a straight line from the current location (112) to the candidate SLZ, thereby generating a trajectory to the candidate SLZ, wherein the straight line is of a particular distance and comprises a total number of discrete points at the particular distance; calculate (308) a risk value quantifying a third party risk associated with operation of the UAV along the respective trajectory to the respective candidate SLZ, a lowest risk value of the risk values being associated with a trajectory from the current location to a selected one of the candidate SLZs; generate or receive (306) a risk map (200) of a geographical area in which the UAV (110) operates, the risk map comprising risk zones (220) of respective risk categories with respective risk weight factors quantifying third party risks associated with operation of the UAV in the risk zones, wherein the trajectory (170) intersects a plurality of the risk zones and the risk value is calculated (308) based on the respective risk weight factors; for a trajectory to the candidate SLZ, separate (308A) the trajectory into segments (170A, 170B) at intersection points with one or more risk zones (220) and calculate (308B) the risk value for the candidate SLZ from the segments and risk weight factors of the one or more risk zones; for each risk zone (220) of the one or more risk zones, determine (308Al) a ratio of a number of discrete points of the trajectory that lie within the risk zone to the total number of the discrete points of the trajectory and calculate (308A2) a product of the ratio and the particular distance, thereby calculating a cross length of the risk zone; calculate (310) a flight termination risk value quantifying a third party risk associated with the UAV immediately landing at the current location; perform (312) a comparison of the lowest risk value and the flight termination risk value; and based on the comparison, perform (314) a sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs or cause the UAV to immediately land at the current location.

2. The device (120, 500) according to claim 1, wherein at least one of the following holds: the processing circuit (502) is further configured to cause the device located on the UAV (110) to autonomously perform the sequence without input from a ground control station, GCS (130), wherein the GCS and the UAV are part of an unmanned aerial system (101); and the UAV (110) is part of an unmanned aerial system (101) that also includes a ground control station, GCS (130), the device is located at the GCS, and the device is caused to perform the sequence by remotely controlling the UAV from the GCS.

3. The device (120, 500) according to claim 1, wherein the device being caused to compute (308B) the risk value for the candidate SLZ (190) includes the device being caused to: compute (308B1) a risk zone risk value for a respective risk zone of the one or more risk zones (220), the risk zone risk value for the risk zone being a product of the cross length of the risk zone and a risk weight factor for a risk category of the risk zone; and sum (308B2) the risk zone risk values to compute the risk value for the candidate SLZ.

4. The device (120, 500) according to claim 1, wherein the device being caused to perform (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one candidate SLZ (190) and with an updated current location (112), the processing circuit (502) is configured to execute the computer-readable program code (506) to cause the device to further: generate or receive (316) an updated risk map (200) for the geographic region in which the UAV (110) operates, the updated risk map including the risk zones (220) with respective updated risk categories having respective updated risk weight factors; compute (318) an updated lowest risk value and an updated flight termination risk value based on the respective updated risk weight factors; and when the updated lowest risk value is greater than the updated flight termination risk value, interrupt (320) the sequence to cause the UAV to immediately land at the updated current location.

5. The device (120, 500) according to any one of claims 1 to 4, wherein, at least one of the following is true: the device being caused to perform (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one candidate SLZ (190) when the lowest risk value is less than or equal to the flight termination risk value and to cause the UAV to immediately land at the current location (112) when the lowest risk value is greater than the flight termination risk value; the device is caused to execute (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one of the candidate SLZs (190) and with an updated current location (112), the processing circuitry (502) being configured to execute the computer readable program code (506) to cause the device to further: compute (318) an updated lowest risk value and an updated flight termination risk value; and interrupt (320) the sequence to cause the UAV to land immediately at the updated current location when the updated lowest risk value is greater than the updated flight termination risk value; and the device is caused to execute (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one of the candidate SLZs (190) and with an updated current location (112), the processing circuitry (502) being configured to execute the computer readable program code (506) to cause the device to further: determine (322) updated candidate SLZs within an updated estimated current range of the UAV from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs; generate (324) updated trajectories for causing the UAV to land in the respective updated candidate SLZs; compute (326) updated risk values and an updated flight termination risk value, a lowest one of the updated risk values being associated with an updated trajectory from the updated current location to a selected one of the updated candidate SLZs; perform (328) a comparison of the lowest updated risk value and the updated flight termination risk value; and based on the comparison, perform (330) an updated sequence to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs or to cause the UAV to land immediately at the updated current location.

6. A method (300) of performing an emergency landing procedure for an unmanned aerial vehicle, UAV, (110), the method comprising the steps of: determining (302) candidate safe landing zones, SLZs, (190) within an estimated current range of the UAV from a current location (112); generating (304) a trajectory (170) for causing the UAV to land in a respective candidate SLZ based on environmental and operational factors affecting flight of the UAV from the current location to the respective candidate SLZ, wherein the step of generating (304) the trajectory (170) comprises, for a candidate SLZ (190), interpolating a straight line from the current location (112) to the candidate SLZ to thereby generate a trajectory to the candidate SLZ, wherein the straight line is a particular distance and comprises a total number of discrete points over the particular distance; computing (308) risk values quantifying third-party risk associated with operation of the UAV along respective trajectories to respective candidate SLZs, a lowest one of the risk values being associated with a trajectory from the current location to a selected one of the candidate SLZs; generating or receiving (306) a risk map (200) of a geographical area in which the UAV (110) operates, the risk map comprising risk zones (220) of respective risk categories having respective risk weight factors quantifying third-party risk associated with operation of the UAV in the risk zones, wherein the trajectory (170) intersects a plurality of the risk zones, and the risk values are computed (308) based on the respective risk weight factors; wherein the step of computing (308) the risk values comprises, for the trajectory: separating (308A) the trajectory into segments (170A, 170B) at intersection points with one or more risk zones (220), and computing (308B) the risk values for the candidate SLZs from the segments and risk weight factors of the one or more risk zones; wherein the step of separating (308A) the trajectory (170) comprises, for each risk zone (220) of the one or more risk zones: determining (308Al) a ratio of a number of discrete points of the trajectory that lie within the risk zone to the total number of the discrete points of the trajectory, and computing (308A2) a product of the ratio and the particular distance, thereby computing a cross length of the risk zone; computing (310) a flight termination risk value quantifying third-party risk associated with the UAV immediately landing at the current location; performing (312) a comparison of the lowest risk value and the flight termination risk value; and based on the comparison, performing (314) a sequence to operate the UAV along the trajectory to the selected one of the candidate SLZs, or to cause the UAV to immediately land at the current location.

7. The method (300) of claim 6, wherein at least one of the following holds: the UAV (110) is part of an unmanned aerial system (101) that further comprises a ground control station GCS (130), the method is performed on the UAV, and the sequence is autonomously performed without input from the GCS; and the UAV (110) is part of an unmanned aerial system (101) that further comprises a ground control station GCS (130), the method is performed at the GCS, and the sequence is performed by remotely controlling the UAV from the GCS.

8. The method (300) of claim 6, wherein, the step of computing (308B) the risk values for the candidate SLZs (190) comprises: computing (308Bl) a risk zone risk value for a respective risk zone of the one or more risk zones (220), the risk zone risk value for the risk zone being a product of the cross length of the risk zone and a risk weight factor of a risk category of the risk zone; and the step of computing (308B) the risk values for the candidate SLZs (190) comprises: computing (308Bl) a risk zone risk value for a respective risk zone of the one or more risk zones (220), the risk zone risk value for the risk zone being a product of the cross length of the risk zone and a risk weight factor of a risk category of the risk zone; and summing (308B2) the risk values for the risk zones to compute the risk value for the candidate SLZ.

9. The method (300) according to any one of claims 6 to 8, wherein, at least one of the following is true: performing (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one of the candidate SLZs (190) when the lowest risk value is less than or equal to the flight termination risk value, and to cause the UAV to land immediately at the current location (112) when the lowest risk value is greater than the flight termination risk value; performing (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one of the candidate SLZs (190) and with an updated current location (112) along the trajectory, the method further comprising: computing (318) an updated lowest risk value and an updated flight termination risk value; and interrupting (320) the sequence to cause the UAV to land immediately at the updated current location when the updated lowest risk value is greater than the updated flight termination risk value; and performing (314) the sequence to operate the UAV (110) along the trajectory (170) to the selected one of the candidate SLZs (190) and with an updated current location (112) along the trajectory, the method further comprising: determining (322) updated candidate SLZs within an updated estimated current range of the UAV from the updated current location, the updated candidate SLZs including the selected one of the candidate SLZs; generating (324) updated trajectories for causing the UAV to land in respective updated candidate SLZs; computing (326) updated risk values and an updated flight termination risk value, a lowest of the updated risk values being associated with an updated trajectory to a selected one of the updated candidate SLZs from the updated current location; performing (328) a comparison of the lowest updated risk value to the updated flight termination risk value; and based on the comparison, performing (330) an updated sequence to operate the UAV along the updated trajectory to the selected one of the updated candidate SLZs, or to cause the UAV to land immediately at the updated current location.

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