System and method for aircraft landing guidance during GNSS denial environments

Abstract

A system includes a GNSS sensor onboard an aircraft; a monitoring warning system (MWS) that determines whether the aircraft is in a GNSS denial environment; and a flight management system including a landing guidance module and a database having position coordinates of landing points. An onboard vision sensor and a radar velocity system (RVS) are in communication with the guidance module. When the MWS determines that the aircraft is in a GNSS denial environment, the guidance module calculates an optimal flight path by: receiving image data from the vision sensor; receiving location, velocity, and altitude data from the RVS; receiving position coordinates of a landing point; processing the image data and the position, speed and altitude data to determine the position of the aircraft and provide 3D imaging of the route to the landing point; and calculating a flight path angle to the landing point using the aircraft and the landing point coordinates.

Description

Background Art

[0001] The landing phase of an aircraft is a critical phase of flight, and controlling the attitude during the landing phase is crucial for a successful landing. For the manual flight of an aircraft, a pilot uses manual control to control the attitude. During the automatic landing of an aircraft, an on-board autopilot system controls the attitude.

[0002] Global Navigation Satellite System (GNSS) sensors on an aircraft, such as Global Positioning System (GPS) sensors, provide landing guidance in the form of the aircraft's landing distance, direction, and position, etc., for the automatic landing or pilot-driven landing of the aircraft. When the aircraft is in a GNSS denied environment, it is difficult to land the aircraft safely at the landing point due to the lack of various parameters such as distance, direction, position, and other parameters. Summary of the Invention

[0003] A system includes a Global Navigation Satellite System (GNSS) sensor on-board an aircraft; a monitoring and warning system operatively communicating with the GNSS sensor, the monitoring and warning system operating to determine whether the aircraft is in a GNSS denied environment; and a flight management system on-board the aircraft, the flight management system including at least one processor hosting a landing guidance module and a navigation database including position coordinates of one or more landing points. One or more visual sensors mounted on the aircraft operatively communicate with the landing guidance module. A Radar Velocity System (RVS) on-board the aircraft operatively communicates with the landing guidance module. An Inertial Navigation System on-board the aircraft operatively communicates with the RVS. When the monitoring and warning system determines that the aircraft is located in a GNSS denied environment, the landing guidance module is activated and operates to calculate an optimal flight path through a process including the steps of: receiving image data from the one or more visual sensors, the image data corresponding to one or more terrain images over which the aircraft is traveling; receiving the position, velocity, and altitude data of the aircraft from the RVS; receiving the position coordinates of a landing point selected by a user from the navigation database; processing the image data and the position, velocity, and altitude data to determine the real-time position of the aircraft and provide a three-dimensional imaging of the route to the landing point; and using the current position coordinates of the aircraft and the position coordinates of the landing point, calculating a landing flight path angle relative to the landing point when the aircraft reaches the landing point. Description of the Drawings

[0004] Aspects of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings. It should be understood that the drawings only show typical embodiments and should not be considered as limiting the scope of the present invention. The present invention will be described with additional features and details by using the drawings, wherein:

[0005] Figure 1 is a block diagram of a system for landing guidance in a GNSS-denied environment according to one embodiment;

[0006] Figure 2 is a flowchart of a method of operation performed by a landing guidance module for an aircraft according to an exemplary embodiment;

[0007] Figure 3 is a schematic diagram of an exemplary landing flight path angle and distance calculation of an aircraft relative to a vertical takeoff and landing airport;

[0008] Figure 4 is a block diagram of a system for generating standard and optimal flight path angle calculations for landing guidance in a GNSS-denied environment according to an exemplary embodiment;

[0009] Figure 5 is a block diagram of a system for aircraft landing guidance in a GPS-denied environment according to an example of an autoland scenario;

[0010] Figure 6 is a flowchart of a method for aircraft landing guidance in a GPS-denied environment according to an example of an autoland scenario;

[0011] Figure 7 is a block diagram of a system for aircraft landing guidance in a GPS-denied environment according to an example of a manual landing scenario;

[0012] Figure 8 is a flowchart of a method for aircraft landing guidance in a GPS-denied environment according to an example of a manual landing scenario;

[0013] Figure 9 is a block diagram of a sensor fusion system for providing landing guidance to an aircraft in a GNSS-denied environment according to an exemplary embodiment; and

[0014] Figure 10 is a block diagram of an aided navigation system for providing landing guidance to an aircraft in a GNSS-denied environment according to an exemplary embodiment. Detailed Description

[0015] In the following detailed description, embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that other embodiments may be utilized without departing from the scope of the invention. Thus, the following detailed description should not be considered limiting.

[0016] Systems and methods for aircraft landing guidance during flight in a GNSS-denied environment are described herein.

[0017] This system generally includes a GNSS sensor on board the aircraft and a monitoring and warning system that communicates with the GNSS sensor, where the monitoring and warning system operates to determine whether the aircraft is in a GNSS-denied environment. The flight management system on board the aircraft includes a landing guidance module and a navigation database that has position coordinates for one or more landing points such as a vertical takeoff and landing (VTOL) airport. The vision system and the radar speed system on the aircraft communicate with the landing guidance module, and the inertial navigation system (INS) on the aircraft communicates with the radar speed system. When the monitoring and warning system determines that the aircraft is flying in a GNSS-denied environment, the landing guidance module is activated and calculates the optimal flight path for the aircraft to land safely.

[0018] For example, when a GNSS interruption is detected, the radar speed system is employed to assist the INS in correcting navigation errors so that the INS continues to provide accurate aircraft position, altitude, and relative speed. Based on these parameters, the landing guidance module calculates the optimal flight path angle, such as the optimal flight path angle to the selected VTOL airport. The optimal flight path angle is used to provide guidance to the pilot or the autopilot system so that the landing of the aircraft is as safe as possible. A vision system such as a camera system can provide more accurate guidance and situational awareness to the pilot. The pilot can use the display system to receive the guidance.

[0019] The selection of the VTOL airport can be done by the pilot or can be done automatically based on the predetermined mission and health condition of the aircraft. For example, the system can run a nearest VTOL airport search algorithm, and the position of the nearest VTOL airport can be provided to the pilot to make the pilot selection process easier. The system then provides the selected VTOL airport position to the landing guidance module for further processing.

[0020] This system can be automatically activated during a GNSS signal interruption and can automatically identify the nearest landing position based on a navigation database (such as a predefined VTOL airport database). The system uses a set of parameters from the INS assisted by the radar speed system (RVS) to calculate a standard flight path angle and a dynamic flight path angle (based on environmental conditions and aircraft configuration) to automatically calculate the optimal flight path angle to a landing area such as the VTOL airport position.

[0021] In addition, the outputs from the radar speed system and the vision system can be integrated to provide the pilot with better situational awareness and obstacle detection capabilities. If the aircraft is far from the VTOL airport position, the system relies on range and speed parameters derived from the INS, the radar speed system, and the vision system to guide and navigate to the selected VTOL airport position in real time. The system can calculate the landing flight path angle by using the latitude and longitude coordinates of the VTOL airport from the navigation database.

[0022] In one scenario, the method enables automatic landing of an aircraft in a GNSS-denied environment by providing an optimal flight path angle to a guidance and navigation control system (such as an autopilot flight control system (AFCS) on board an aircraft). In another scenario, the optimal flight path angle can be used to effectively guide a pilot when navigating an aircraft in a GNSS-denied environment by providing landing guidance to the pilot for manual landing of the aircraft. The pilot can use the optimal flight path angle along with camera guidance for increased situational awareness to perform a safe landing of the aircraft.

[0023] The system and method can be used to provide safe landings of various vehicles in a GNSS-denied environment. Examples of such vehicles include manned aircraft, unmanned aircraft, vertical takeoff and landing (VTOL) aircraft, urban air mobility (UAM) vehicles, and the like.

[0024] Additional details of various embodiments are described below and with reference to the drawings.

[0025] Figure 1 A system 100 for landing guidance in a GNSS-denied environment according to one embodiment is shown. System 100 is implemented on an aircraft 102 such as a UAM vehicle, a UAS vehicle, and the like. System 100 generally includes a GNSS sensor 110 on board the aircraft 102, and a monitoring and warning system 114 operatively communicating with the GNSS sensor 110. The monitoring and warning system 114 operates to determine whether the aircraft 102 is in a GNSS-denied environment. System 100 also includes a flight management system 120 on board the aircraft 102 and operatively communicating with the monitoring and warning system 114.

[0026] The flight management system 120 includes at least one processor 122 hosting a landing guidance module 124 and a navigation database 126 including position coordinates of one or more landing points. System 100 also includes one or more vision sensors 130 mounted on the aircraft 102 and operatively communicating with the landing guidance module 124, such as one or more IR cameras. An on-board radar velocity system (RVS) 134 also operatively communicates with the landing guidance module 124, and an on-board inertial navigation system (INS) 138 communicates with the radar velocity system 134.

[0027] During operation of the system 100, when the monitoring and warning system 114 determines that the aircraft 102 is located in a GNSS-denied environment, the landing guidance module 124 is activated. As further described below, the landing guidance module 124 then calculates an optimal landing flight path angle for the aircraft 102 relative to a landing point based on various inputs received from the sensors employed in the system 100. For example, the landing guidance module may receive depth and velocity estimates from the radar velocity system 134 to calculate the optimal landing flight path angle.

[0028] In some embodiments, the on-board display system 140 operates communicatively with the landing guidance module 124 and the vision sensor 130. The display system 140 is configured to receive various inputs, such as a three-dimensional (3D) view from the vision sensor 130, to provide more accurate guidance to the pilot for situational awareness. Additionally, the display system 140 may show a guidance path based on the optimal landing flight path angle calculated by the landing guidance module 124, and may announce a message when the landing guidance module is activated.

[0029] In some embodiments, the flight management system 120 may also include a nearest landing point algorithm on the navigation database 126. The nearest landing point algorithm operates to provide an optimal landing point based on the state of the aircraft 102 and the availability of the landing location.

[0030] In some embodiments, the landing guidance module operates to send a guidance path based on the optimal landing flight path angle to an automatic flight control system (AFCS) on the aircraft 102. The AFCS is configured to follow the guidance path to perform a safe automatic landing of the aircraft 102 at the landing point.

[0031] In some embodiments, the landing guidance module operates to provide a guidance path based on the optimal landing flight path angle to the pilot of the aircraft, such that the pilot may follow the guidance path to perform a safe landing of the aircraft 102 at the landing point.

[0032] Figure 2 is a flowchart of an operating method 200 performed by a landing guidance module of an aircraft (such as landing guidance module 124) according to an exemplary embodiment. Method 200 includes receiving image data from one or more vision sensors on-board the aircraft (e.g., IR cameras), where the image data corresponds to one or more terrain images of the terrain over which the aircraft is traveling captured by the one or more vision sensors (block 210). Method 200 also includes receiving the position, speed, and altitude data of the aircraft from a radar speed system such as RVS 134 (block 220); and receiving the position coordinates of a user-selected landing point from a navigation database such as navigation database 126 (block 230). Method 200 then includes processing the image data and the position, speed, and altitude data to determine the real-time position of the aircraft, and providing a 3D imaging of the route to the landing point (block 240). Method 200 also includes calculating a landing flight path angle relative to the landing point when the aircraft approaches the landing point using the current position coordinates of the aircraft and the position coordinates of the landing point (block 250).

[0033] The various subsystems used in this method are described in further detail below.

[0034] Sensor system

[0035] Inputs from multiple sensor systems are implemented by this method. These inputs include inputs from GNSS sensors such as GPS sensors, radar speed systems, and vision systems such as camera systems.

[0036] When a GNSS denied environment is detected, GNSS sensor parameters from the GNSS sensors are used to initiate the landing guidance function. For example, when the GNSS signal value is below a user-selected threshold level, the monitoring warning system activates the landing guidance module.

[0037] The RVS can be provided as a small size, weight, and power (SWaP), radar-based navigation aid system. The RVS uses millimeter wave (mm wave) sensing technology (e.g., approximately 60 GHz - 64 GHz or approximately 76 GHz - 81 GHz) and outputs the range, speed, and angle of an object. The RVS can provide centimeter (cm)-level radar accuracy and is not affected by environmental conditions such as rain, fog, dust, or snow.

[0038] The RVS is installed on the aircraft together with the INS to provide various parameters such as the current position coordinates, altitude of the aircraft, depth (range) to land, relative speed, etc. The RVS can act as a speed aid while providing altitude measurement, depth mapping, and ground avoidance. The RVS can be used for depth sensing to provide an accurate measurement of the path between the aircraft and the landing point. For example, the RVS can transmit radio waves to a vertical takeoff and landing airport, and based on the reflection of these radio waves from the vertical takeoff and landing airport in a GNSS denied environment, it can provide different parameters required to calculate the landing path. The RVS together with the INS provides the current position coordinates (latitude / longitude), which are used to calculate the landing path angle in the landing guidance module for calculating the landing path.

[0039] The vision system can include one or more cameras installed on the aircraft to provide a 360-degree view of the environment around the aircraft during flight. The one or more cameras can include infrared (IR) cameras for low visibility conditions. Image data from the cameras can be fused together to produce a 3D rendering of the landing point, thus providing guidance and navigation for the safe landing of the aircraft in a GPS denied environment.

[0040] The RVS and INS provide safe landing navigation during continuous GNSS outages. When the input from the vision system is paired with the input from the RVS, through the use of sensor fusion technology, the pilot can have a higher level of situational awareness, thus allowing for a more accurate landing of the aircraft.

[0041] Monitoring warning system and display system

[0042] A monitoring and warning system installed on an aircraft is configured to detect weak GNSS signals to identify GNSS-denied environments. The monitoring and warning system receives the position of the nearest vertical takeoff and landing (VTOL) airport selected by the pilot and receives GNSS signals for detecting the GNSS signal strength. When the aircraft is near the VTOL airport and the GNSS signal is weak or lost, the monitoring and warning system uses the VTOL airport position to activate the landing guidance system. As further described below, the VTOL airport position is also used by the landing guidance system to calculate the landing flight path of the aircraft.

[0043] The display system is configured to receive various inputs from different subsystems. For example, the display system can show a camera view to improve pilot situational awareness, such as a 3D view of the camera to provide more accurate guidance to the pilot. Additionally, the display system can show the optimal flight path of the aircraft and can announce a message based on the activation of the landing guidance system.

[0044] Flight management system

[0045] The flight management system (FMS) is configured to receive various inputs from the sensor system, the monitoring and warning system, and the display system. As previously mentioned, the flight management system includes a landing guidance module and a navigation database that has position coordinates of landing points such as VTOL airports. The landing guidance module receives the VTOL airport position from the display system and receives the current position, altitude, and speed of the aircraft from the RVS. The landing guidance module also receives image data from the vision system. The landing guidance module can use the image data and RVS data to determine the real-time position in space using visual simultaneous localization and mapping (VSLAM) for 3D imaging of the route to the nearest VTOL airport position. The landing guidance module also provides outputs to the display system and / or the AFCS.

[0046] The flight management system is configured to run a nearest VTOL airport search algorithm on the navigation database to provide the nearest VTOL airport information to the display for VTOL airport position selection. When the aircraft is in a GNSS-denied environment, the selected VTOL airport position is sent to the monitoring and warning system for activating the landing guidance module. Once the VTOL airport position is selected and the landing guidance module is activated, the VTOL airport position is also shared with the landing guidance module for calculating the optimal flight path.

[0047] When the aircraft approaches near the selected VTOL airport, if the VTOL airport is in the line of sight (LOS) of the aircraft, the landing guidance module uses the current aircraft position coordinates and the VTOL airport position coordinates to calculate the landing flight path angle relative to the VTOL airport.

[0048] Figure 3It is a schematic diagram of an exemplary landing flight path angle and distance calculation 300 for an aircraft. As Figure 3 shown in, if the UAM vehicle 310 is at position A with the first latitude and longitude coordinates (Lat1, Lon1), and the vertical takeoff and landing airport 320 is at position B with the second latitude and longitude coordinates (Lat2, Lon2), the following formula can be applied to obtain the landing flight path angle (FPA) 330 at the current altitude (height):

[0049] Current landing FPA (radians) = atan2(Lon2 - Lon1, Lat2 - Lat1) (1)

[0050] Current landing FPA (degrees) = atan2(Lon2 - Lon1, Lat2 - Lat1) * 180 / Pi (2)

[0051] Formulas (1) and (2) can be used to continuously calculate the current landing flight path angle at different altitudes, where altitude information and the latest coordinates are provided by the RVS together with the INS.

[0052] The required optimal (Opt) flight path angle can be based on the standard landing flight path angle, the optimal landing flight path angle for a specific aircraft configuration (A / C config), or the flight path angle based on environmental conditions (e.g., wind, meteorological information from the weather radar, obstacles detected by the RVS system, etc.). The formula for calculating the required optimal flight path angle is as follows:

[0053] Required landing FPA (Opt) = Function(landing FPA(Std), Dyn FPA(Env, A / C

[0054] config))(3)

[0055] where landing FPA(Std) is the standardized landing flight path angle for an effective landing, and Dyn FPA(Env) is the dynamic flight path angle calculated by the flight management system based on external environmental conditions (e.g., wind, meteorology, obstacles, etc.).

[0056] Using the current landing FPA calculated in formula (2) and the required landing FPA(Opt) in formula (3), the optimal flight path angle can be calculated at different altitudes as follows:

[0057] Optimal flight path angle = Function(required landing FPA(Opt), landing

[0058] FPA(current altitude, speed)(4)

[0059] The optimal flight path angle calculated in Equation 4 can be used to align the aircraft with the flight angle required for a safe landing. The algorithms represented by Equations (1)-(4) can run continuously until the aircraft has executed a safe landing. Additionally, the optimal flight path angle can be used to obtain landing distance information using the following formula:

[0060] Distance = Height / tan(Landing Angle) (5)

[0061] Figure 4 FIG. 7 is a block diagram of a system 400 for generating standards and optimal flight path angle calculations for the landing guidance of an aircraft 402 in a GNSS-denied environment, in accordance with an exemplary embodiment. The system 400 generally includes a landing guidance module 410 located in the flight management system (FMS) of the aircraft 402 and a vertical takeoff and landing (VTOL) airport database 420 that is also part of the FMS. Additionally, various on-board sensor systems communicate with the landing guidance module 410, including a camera 432 and a radar velocity system (RVS) 434. An inertial navigation system (not shown) on-board the aircraft 402 operates in communication with the RVS 434.

[0062] The landing guidance module 410 is configured to receive the current latitude and longitude coordinates of the aircraft from the RVS 434 (block 412). The landing guidance module 410 uses the current latitude and longitude coordinates of the aircraft (from block 412) and the selected VTOL airport location (with latitude and longitude coordinates) provided by the VTOL airport database 420 to calculate the landing FPA(Std) according to Equations (1) and (2) (block 414).

[0063] The landing guidance module 410 also provides the FPA required for a safe landing (based on wind, environmental conditions, landing procedure) (block 416). The landing guidance module 410 calculates the optimal required FPA (block 418) based on the landing FPA(Std) (from block 414), the required FPA (from block 416), the image data from the camera 432, and the speed and depth estimates from the RVS 434. The calculated optimal required FPA is then output as part of a guidance command for use by an automatic flight control system (AFCS) or a pilot (block 440) to assist in providing a safe landing of the aircraft 402 at the VTOL airport.

[0064] Aircraft landing scenario

[0065] Figure 5It is a functional block diagram of a system 500 for aircraft landing guidance in a GPS-denied environment according to an example of an automatic landing scenario. The system 500 generally includes a GPS sensor 510 on board the aircraft, a flight management system 520 on board the aircraft, and various on-board sensor systems 530 that communicate with the flight management system 520. The flight management system 520 includes a landing guidance system 522 for flight path calculation, and a navigation database 524 that includes a vertical takeoff and landing (VTOL) airport search algorithm and VTOL airport position coordinates. The sensor system 530 includes a vision system (camera) 532, a radar velocity system (RVS) 534, and an inertial navigation system (INS) 536 that operates in communication with the RVS 534. Additionally, a display system can operate in communication with the landing guidance system 522, the navigation database 524, and the vision system 532. An automatic flight control system (AFCS) 540 on board the aircraft operates in communication with the landing guidance system 522.

[0066] During the operation of the system 500 for automatic landing, the VTOL airport search algorithm on the navigation database 524 provides a list of the nearest VTOL airports to the display system for the pilot's selection of a VTOL airport (block 542). The GPS sensor 510 sends a GPS signal to a monitoring and warning system (MWS) at 514, which determines whether to activate the landing guidance system 522. Additionally, the VTOL airport position selected by the pilot is sent to the MWS at 514 and is sent to the landing guidance system 522. If the MWS determines that there is a good GPS signal, the landing guidance system 522 is not activated, and the aircraft follows the original flight plan using the good GPS signal (block 516). If the MWS determines that the aircraft is in a GPS-denied environment, the landing guidance system 522 is activated.

[0067] The landing guidance system 522 calculates an optimal flight path relative to the selected VTOL airport position based on various inputs received from the sensor system 530. For example, the landing guidance system 522 can receive current position, depth, and speed data from the RVS 534, and can receive 3D imaging of the route to the nearest VTOL airport from the vision system 532. The calculated optimal flight path is sent to the display system, which shows the optimal flight path together with the camera view Figure 1 (block 544). The camera view is sent to the display system through the vision system 532 to provide the pilot with more accurate guidance and situational awareness. The optimal flight path is also sent to the AFCS 540, which provides automatic landing of the aircraft based on the optimal path loaded on the flight management system (FMS) (block 550).

[0068] Figure 6It is a flowchart of a method 600 for aircraft landing guidance in a GPS-denied environment according to an example of an automatic landing scenario. First, the method 600 starts with a pilot-selected automatic landing at 610. A vertical takeoff and landing (VTOL) airport search algorithm (block 612) on a navigation database (DB) including a VTOL airport location database provides a list of the nearest VTOL airports to a display system for the pilot to select a VTOL airport (block 614). The selected VTOL airport location is sent to a monitoring and warning system (MWS) at 616, which is also configured to receive GPS signals 618 to determine whether the aircraft is in a GPS-denied environment. If the MWS determines that the aircraft is not in a GPS-denied environment, the aircraft follows the original flight plan with GPS-based guidance (block 620), and the method 600 ends at 622. If the MWS determines that the aircraft is in a GPS-denied environment, the method 600 activates the landing guidance system through the MWS (block 624).

[0069] The RVS scans the entire area around the aircraft (block 626) and provides various parameters such as the current position, altitude, etc. to the landing guidance system (block 628), and the landing guidance system also receives the selected VTOL airport location. The landing guidance system calculates and outputs the best path for the aircraft. The best path is sent to the display system, which shows it together with the camera view Figure 1 (block 630). The camera view is provided by the guidance of the camera vision system (block 632), so that the guidance of the surrounding area for a safe landing is sent to the display system. The method 600 ends at 634, where the best path is sent to the AFCS, and the AFCS follows the guidance based on the best path to provide an automatic landing for the aircraft.

[0070] Figure 7 It is a functional block diagram of a system 700 for aircraft landing guidance in a GPS-denied environment according to an example of a manual landing scenario. The system 700 generally includes a GPS sensor 710 on board the aircraft, a flight management system 720 on board the aircraft, and various on-board sensor systems 730 communicating with the flight management system 720. The flight management system 720 includes a landing guidance system 722 for flight path calculation, and a navigation database 724 including a VTOL airport search algorithm and VTOL airport location coordinates. The sensor system 730 includes a vision system (camera) 732, a radar velocity system (RVS) 734, and an inertial navigation system (INS) 736 operating in communication with the RVS 734. Additionally, the display system can operate in communication with the landing guidance system 722, the navigation database 724, and the vision system 732.

[0071] During the operation of the system 700 for manual landing, the vertical takeoff and landing (VTOL) airport search algorithm on the navigation database 724 provides a list of the nearest VTOL airports to the display system for the pilot to select a VTOL airport (block 742). The GPS sensor 710 sends a GPS signal to the Monitoring and Warning System (MWS) at 714, which determines whether to activate the landing guidance system 722. Additionally, the VTOL airport position selected by the pilot is sent to the MWS at 714 and is sent to the landing guidance system 722. If the MWS determines that there is a good GPS signal, the landing guidance system 722 is not activated, and the aircraft follows the original flight plan using the good GPS signal (block 716). If the MWS determines that the aircraft is in a GPS denied environment, the landing guidance system 722 is activated.

[0072] The landing guidance system 722 calculates the best flight path relative to the selected VTOL airport position based on various inputs received from the sensor system 730. For example, the landing guidance system 722 may receive current position, altitude, and speed data from the RVS 734 and may receive 3D imaging of the route to the nearest VTOL airport from the vision system 732. The calculated best flight path is sent to the display system, which superimposes the best flight path with the camera view Figure 1 and shows it (block 744). The camera view is sent to the display system through the vision system 732 to provide the pilot with more accurate guidance and situational awareness. The displayed best flight path and camera view allow the pilot to follow the best path based on the guidance (block 750) to safely land the aircraft at the VTOL airport.

[0073] Figure 8 is a flowchart of a method 800 for aircraft landing guidance in a GPS denied environment according to an example of a manual landing scenario. First, the method 800 starts with a manual landing selected by the pilot at 810. The VTOL airport search algorithm (block 812) on the navigation database, which includes a VTOL airport position database, provides a list of the nearest VTOL airports to the display system for the pilot to select a VTOL airport (block 814). The selected VTOL airport position is sent to the Monitoring and Warning System (MWS) at 816, which is also configured to receive a GPS signal 818 to determine whether the aircraft is in a GPS denied environment. If the MWS determines that the aircraft is not in a GPS denied environment, the aircraft follows the original flight plan with GPS-based guidance (block 820), and the method 800 ends at 822. If the MWS determines that the aircraft is in a GPS denied environment, the method 800 activates the landing guidance system (block 824).

[0074] The RVS scans the entire area around the aircraft (block 826) and provides various parameters such as the current position, altitude, etc. to the landing guidance system (block 828), which also receives the selected vertiport location. The landing guidance system calculates and outputs the optimal path of the aircraft. The optimal path is sent to the display system, which presents the optimal path in conjunction with the camera view Figure 1 (block 830). The camera view is provided under the guidance of the camera vision system (block 832), so that the surrounding area guidance for safe landing is sent to the display system. Method 800 ends at 834, where the displayed optimal path and camera view allow the pilot to follow the guidance to safely land the aircraft at the vertiport.

[0075] Sensor fusion system

[0076] Figure 9 is a block diagram of a sensor fusion system 900 for providing landing guidance for an aircraft in a GNSS-denied environment according to an exemplary embodiment. The sensor fusion system 900 operates to process and fuse data provided by various sensor inputs. The sensor fusion system 900 generally includes an input stage 910, a data processing stage 920 operatively communicating with the input stage 910, and a perception stage 930 operatively communicating with the data processing stage 920.

[0077] The input stage 910 includes a camera vision system 912 configured to generate image data 914 and a radar velocity system (RVS) 916 configured to generate radar data 918. The data processing stage 920 is configured to collect data at 922, format data at 923, synchronize camera data at 924, and calibrate data at 925. The perception stage 930 is configured to detect the fused data at 932 and provide an output including a visual image of the aircraft landing area 942 at 940.

[0078] In an exemplary operation of the sensor fusion system 900, a camera unit of the camera vision system 912 captures a 360-degree image of an aircraft landing approach area, and image data 914 corresponding to the captured image is sent to the data processing stage 920. Additionally, the RVS 916 scans the landing approach area, and radar data 918 corresponding to the scanned landing approach area (e.g., the depth of the landing approach area) is sent to the data processing stage 920. The data processing stage 920 operates to collect the received data at 922, format the collected data at 923, synchronize the camera data at 924, and calibrate the data at 925. The processed and fused data is sent from the data processing stage 920 to the perception stage 930, which detects the fused data at 932 to generate a visual image of the landing approach area. The visual image is output at 940, such as to a display system, to show the landing area 942 for the pilot of the aircraft to view.

[0079] RVS assisted navigation system

[0080] Figure 10 is a block diagram of a RVS-aided navigation system 1000 according to an exemplary embodiment for providing landing guidance for an aircraft in a GNSS-denied environment. The aided navigation system 1000 includes an INS 1010 that operates in communication with an inertial measurement unit (IMU) 1012, which operates to generate inertial measurements of the aircraft. The IMU 1012 includes a set of gyroscopes 1014 and accelerometers 1016. The aided navigation system 1000 also includes at least one processor that includes a navigation formula 1020 operating in communication with the INS 1010 and the IMU 1012. The navigation formula 1020 operates to receive angular velocity and specific force data from the IMU 1012. The aided navigation system 1000 also includes an error state Kalman filter 1030 operating in communication with the navigation formula 1020, and a radar velocity system (RVS) 1040 operating in communication with the navigation formula 1020 and the error state Kalman filter 1030.

[0081] During operation, the INS 1010 provides angular velocity and specific force data from the IMU 1012 to the navigation formula 1020, which generates speed, depth, attitude, and horizontal position parameters of the aircraft. Errors in these parameters are corrected by means of the RVS 1040 and the error state Kalman filter 1030. The RVS 1040 helps correct speed and position errors from the initial position and speed provided by the INS 1010. The error correction signal is sent from the error state Kalman filter 1030 to the navigation formula 1020 in the reset feedback loop 1034 to provide updated parameters.

[0082] For example, speed data can be sent from the navigation formula 1020 to the adder / subtractor 1042, which also receives RVS data from the RVS 1040. The combined speed and RVS data are then sent from the adder / subtractor 1042 to the error state Kalman filter 1030 for further processing. Depth data can be sent from the navigation formula 1020 to the adder / subtractor 1044, which also receives RVS data from the RVS 1040. The combined depth and RVS data are then sent from the adder / subtractor 1044 to the error state Kalman filter 1030 for further processing. Attitude data can be sent from the navigation formula 1020 to the adder / subtractor 1046, which also receives RVS data from the RVS 1040. The combined attitude and RVS data are then sent from the adder / subtractor 1046 to the error state Kalman filter 1030 for further processing. Horizontal position data can be sent from the navigation formula 1020 to the adder / subtractor 1048, which also receives RVS data from the RVS 1040. The combined horizontal position and RVS data are then sent from the adder / subtractor 1048 to the error state Kalman filter 1030 for further processing.

[0083] One or more processors and / or other computing devices used in the methods and systems described herein can be implemented using software, firmware, hardware, or a suitable combination thereof. The processor and / or other computing devices can be supplemented or incorporated by a dedicated application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) designed specifically for that purpose. In some specific implementations, the processor and / or other computing devices can communicate with other computing devices external to the navigation system through one or more transceivers, such as computing devices associated with a management system or computing devices associated with other subsystems controlled by the management system. The processor and / or other computing devices can also include software programs, firmware, or other computer-readable instructions or operate with them to perform various processing tasks, calculations, and control functions used in the methods and systems described herein.

[0084] The methods described herein can be implemented by computer-executable instructions (such as program modules or components) executed by at least one processor or processing unit. Generally, program modules include routines, programs, objects, data components, data structures, algorithms, etc. that perform specific tasks or implement specific abstract data types.

[0085] The various process tasks, calculations, and generated instructions for other data used in performing the methods described herein can be implemented in software, firmware, or other computer-readable instructions. These instructions are typically stored on a suitable computer program product, which includes a computer-readable medium for storing computer-readable instructions or data structures. Such computer-readable media can be any available media that can be accessed by a general-purpose or special-purpose computer or processor or any programmable logic device.

[0086] Suitable computer-readable storage media can include, for example, non-volatile memory devices, including semiconductor memory devices such as random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), or flash memory devices; magnetic disks such as internal hard disks or removable disks; optical storage devices such as compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs; or any other medium that can be used to carry or store the desired program code in the form of computer-executable instructions or data structures.

[0087] Example implementation

[0088] Example 1 includes a system that includes: a global navigation satellite system (GNSS) sensor on board an aircraft; a monitoring and warning system operatively communicating with the GNSS sensor, the monitoring and warning system operative to determine whether the aircraft is in a GNSS denied environment; a flight management system on board the aircraft, the flight management system including at least one processor hosting a landing guidance module and a navigation database including position coordinates of one or more landing points; one or more vision sensors mounted on the aircraft and operatively communicating with the landing guidance module; a radar velocity system (RVS) on board the aircraft and operatively communicating with the landing guidance module; and an inertial navigation system on board the aircraft and operatively communicating with the RVS; wherein when the monitoring and warning system determines that the aircraft is located in a GNSS denied environment, the landing guidance module is activated and operative to calculate an optimal flight path by a process including the steps of: receiving image data from the one or more vision sensors, the image data corresponding to one or more terrain images over which the aircraft is traveling; receiving the position, velocity, and altitude data of the aircraft from the RVS; receiving the position coordinates of a user-selected landing point from the navigation database; processing the image data and the position, velocity, and altitude data to determine the real-time position of the aircraft and provide a three-dimensional (3D) imaging of the route to the landing point; and using the current position coordinates of the aircraft and the position coordinates of the landing point, calculating a landing flight path angle relative to the landing point when the aircraft reaches the landing point.

[0089] Example 2 includes the system of Example 1, wherein the flight management system further includes a nearest landing point algorithm that operates to provide an optimal landing point based on the state of the aircraft and the availability of landing positions.

[0090] Example 3 includes the system of any one of Examples 1 to 2, wherein the landing guidance module further operates to receive depth and speed estimates from the RVS to calculate an optimal flight path angle.

[0091] Example 4 includes the system of Example 3, wherein the landing guidance module operates to send a guidance path based on the optimal flight path angle to an automatic flight control system (AFCS) on the aircraft, wherein the AFCS is configured to follow the guidance path to perform a safe landing of the aircraft at the landing point.

[0092] Example 5 includes the system of Example 3, wherein the landing guidance module operates to provide a guidance path based on the optimal flight path angle to the pilot of the aircraft, such that the pilot can follow the guidance path to perform a safe landing of the aircraft at the landing point.

[0093] Example 6 includes the system of any one of Examples 1 to 5, wherein the one or more visual sensors include one or more infrared (IR) cameras.

[0094] Example 7 includes the system of any one of Examples 1 to 6, further including a display system configured to receive a plurality of inputs, including a 3D camera view for providing accurate guidance and situational awareness to the pilot.

[0095] Example 8 includes the system of Example 7, wherein the display system is configured to show a guidance path based on the optimal flight path angle calculated by the landing guidance module and announce a message when the landing guidance module is activated.

[0096] Example 9 includes the system of any one of Examples 1 to 8, wherein the aircraft is a manned aircraft.

[0097] Example 10 includes the system of any one of Examples 1 to 8, wherein the aircraft is an unmanned aircraft.

[0098] Example 11 includes the system of any one of Examples 1 to 10, wherein the aircraft includes a vertical takeoff and landing (VTOL) aircraft or an urban air mobility (UAM) vehicle.

[0099] Example 12 includes a method of generating landing guidance for an aircraft, the method including: sending a list of the nearest vertical takeoff and landing (VTOL) airport positions from a VTOL airport position database to a display system for a user to select a VTOL airport position; sending the selected VTOL airport position to a monitoring and warning system that is also configured to receive Global Navigation Satellite System (GNSS) signals; determining in the monitoring and warning system whether the aircraft is in a GNSS denied environment; wherein if the aircraft is not in a GNSS denied environment, the aircraft continues to follow an original flight plan with GNSS-based guidance; wherein if the aircraft is in a GNSS denied environment, activating a landing guidance system, the method further including: scanning an area around the aircraft with a Radar Velocity System (RVS) to obtain a set of parameters, the set of parameters being sent from the RVS to the landing guidance system; obtaining image data using a camera vision system of the area around the aircraft, the image data being sent from the camera vision system to the landing guidance system; sending the selected VTOL airport position to the landing guidance system; calculating, using the landing guidance system, an optimal path to the selected VTOL airport position based on the set of parameters from the RVS and the image data from the camera vision system; displaying the optimal path on the display system; and displaying a three-dimensional (3D) camera view from the camera vision system on the display system.

[0100] Example 13 includes the method of Example 12, wherein the landing guidance system sends the optimal path to an Automatic Flight Control System (AFCS) on the aircraft such that the AFCS follows the optimal path to perform an automatic landing of the aircraft at the selected VTOL airport position.

[0101] Example 14 includes the method of Example 12, wherein the displayed optimal path and 3D camera view are used by a pilot to perform a manual landing of the aircraft at the selected VTOL airport position.

[0102] Example 15 includes the method of any one of Examples 12 to 14, wherein the set of parameters from the RVS includes position, altitude, depth, and velocity estimates.

[0103] Example 16 includes the method of any one of Examples 12 to 15, wherein the landing guidance system uses the set of parameters from the RVS to calculate an optimal flight path angle relative to the selected VTOL airport position.

[0104] Example 17 includes the method of Example 16, wherein the optimal flight path angle is automatically calculated based on a standard flight path angle and a dynamic flight path angle.

[0105] Example 18 includes the method of Example 17, wherein: the standard flight path angle is calculated based on the current position coordinates of the aircraft and the position coordinates of the selected vertical takeoff and landing airport; and the dynamic flight path angle is calculated based on environmental conditions and the configuration of the aircraft.

[0106] Example 19 includes the method of any one of Examples 12 to 18, wherein the aircraft includes a vertical takeoff and landing (VTOL) aircraft or an urban air mobility (UAM) vehicle.

[0107] Example 20 includes a program product, the program product comprising: a non-transitory computer-readable medium having stored thereon instructions executable by a processor to perform a method for landing guidance of an aircraft, the method comprising: receiving, in the processor, image data from a camera vision system on board the aircraft, the image data corresponding to one or more terrain images along which the aircraft is traveling; receiving, in the processor, radar data including position, speed, and altitude data from a radar speed system on board the aircraft; receiving, in the processor, position coordinates of a vertical takeoff and landing airport from a vertical takeoff and landing airport position database on board the aircraft; processing the image data and the radar data together to determine the real-time position of the aircraft and provide a three-dimensional imaging of a route approaching the vertical takeoff and landing airport; and calculating, using the current position coordinates of the aircraft and the position coordinates of the vertical takeoff and landing airport, a landing flight path angle relative to the vertical takeoff and landing airport when the aircraft approaches the vertical takeoff and landing airport.

[0108] The present invention may be embodied in other specific forms without departing from its basic characteristics. The embodiments are to be considered in all respects only as illustrative and not restrictive. Thus, the scope of the present invention is indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A system, the system comprising: A global navigation satellite system (GNSS) sensor on board an aircraft; A monitoring and warning system operatively communicating with the GNSS sensor, the monitoring and warning system operative to determine whether the aircraft is in a GNSS denied environment; A flight management system on board the aircraft, the flight management system including at least one processor hosting a landing guidance module and a navigation database including position coordinates of one or more landing points; One or more vision sensors mounted on the aircraft and operatively communicating with the landing guidance module; A radar velocity system (RVS) on board the aircraft and operatively communicating with the landing guidance module; and An inertial navigation system on board the aircraft and operatively communicating with the RVS; Wherein when the monitoring and warning system determines that the aircraft is located in a GNSS denied environment, the landing guidance module is activated and operative to calculate an optimal flight path through a process including the steps of: Receiving image data from the one or more vision sensors, the image data corresponding to one or more terrain images over which the aircraft is traveling; Receiving the position, velocity, and altitude data of the aircraft from the RVS; Receiving the position coordinates of a landing point selected by a user from the navigation database; Processing the image data and the position, velocity, and altitude data to determine the real-time position of the aircraft and provide a three-dimensional (3D) imaging of the route to the landing point; And Using the current position coordinates of the aircraft and the position coordinates of the landing point, calculating a landing flight path angle relative to the landing point when the aircraft reaches the landing point.

2. The system according to claim 1, wherein: The flight management system further includes a nearest landing point algorithm, the nearest landing point algorithm operative to provide an optimal landing point based on the state of the aircraft and the availability of landing positions; and The landing guidance module is further operative to receive depth and velocity estimates from the RVS to calculate the optimal flight path angle.

3. A method of generating landing guidance for an aircraft, the method comprising: Sending a list of nearest vertical takeoff and landing airports from a vertical takeoff and landing airport location database to a display system for a user to select a vertical takeoff and landing airport location; Sending the selected vertical takeoff and landing airport location to a monitoring and warning system, the monitoring and warning system further configured to receive global navigation satellite system (GNSS) signals; Determining in the monitoring and warning system whether the aircraft is in a GNSS denied environment; Wherein if the aircraft is not in a GNSS denied environment, the aircraft continues to follow an original flight plan with GNSS-based guidance; Wherein if the aircraft is in a GNSS denied environment, activating a landing guidance system, the method further comprising: Scanning an area around the aircraft with a radar velocity system (RVS) to obtain a set of parameters, the set of parameters being sent from the RVS to the landing guidance system; Obtain image data using a camera vision system in the area around the aircraft, and send the image data from the camera vision system to the landing guidance system; Send the selected vertical takeoff and landing airport location to the landing guidance system; Based on the set of parameters from the RVS and the image data from the camera vision system, use the landing guidance system to calculate the optimal path to the selected vertical takeoff and landing airport location; Display the optimal path on the display system; and Display a three-dimensional (3D) camera view from the camera vision system on the display system.

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