Method for determining a take-off / landing state of a VTOL aircraft and VTOL aircraft

Abstract

Aircraft (200), preferably eVTOL aircraft (200), said aircraft (200) comprising: an inertial measurement device (1) configured to provide a first indicator signal (102a) corresponding to the kinematics of the VTOL aircraft (200), an indication device (4) which is different from the inertial measuring device (1) and in particular independent of the inertial measuring device (1), and which is configured to provide a second indicator signal (4b, 5b, 6a, 7a) which is different from the first indicator signal (102a), and a determination device (101) which is configured to process the first indicator signal (102a) and the second indicator signal (4b, 5b, 6a, 7a), in particular to combine them logically, in order to provide a status signal (101a) which correlates with a take-off / landing state of the VTOL aircraft (200), wherein the indication device (4) is a Baro-Altimeter (4) and the Baro-Altimeter (4) is configured to provide the second indicator signal (4b) indicating a take-off state of the VTOL aircraft (200) when the ambient air pressure measured by the Baro-Altimeter (4) increases or the altitude measured by the Baro-Altimeter (4) decreases.

Description

[0001] Method for determining a take-off / landing state of a VTOL aircraft and

[0002] VTOL aircraft

[0003] Technical field

[0004] The invention relates to a method for determining a take-off / landing state of an aircraft configured for vertical take-off and landing (VTOL aircraft).

[0005] The invention also relates to a VTOL aircraft, in particular an electrically powered eVTOL aircraft, in which the method according to the invention can be used.

[0006] Background

[0007] Typically, aircraft, especially VTOL aircraft, i.e. aircraft with vertical take-off and landing capability, have functions that require input information as to whether the aircraft is on the ground or in the air. Traditionally, this information is obtained with the help of so-called weight-on-wheel (WoW) sensors, such as a so-called squat switch. A common application for fixed-wing aircraft involves combining this information with a landing gear mechanism or thrust reverser actuation. For rotorcraft, it is also known to provide special pressure detectors on the landing gear in order to determine the pressure in the landing gear caused by the weight of the aircraft on the ground.

[0008] An incorrect determination of the take-off / landing status of an aircraft can have catastrophic consequences. It is therefore common practice to install several weight-on-wheel sensors in order to fulfil the redundancy requirements of the certification regulations. The problem of a possible common-mode error of the sensors must also be solved, for example through design differences of different sensors. This further increases the complexity of the architecture, the overall weight of the aircraft and, last but not least, the costs. In principle, a disadvantage of the afore-mentioned prior art is that additional sensors are used in order to determine the aforementioned information, i.e. whether the aircraft is in a so-called "ground mode" (i.e. on the ground) or in "flight mode" (i.e. in the air), which means additional constructive effort and, in particular, increases the weight of the aircraft. However, weight reduction is a decisive factor, particularly in the case of the electrically powered (e)VTOL aircraft provided by the applicant.

[0009] Summary of the invention

[0010] It is therefore an object of the present invention to satisfy the aforementioned requirements and / or to eliminate the disadvantages associated with the prior art. In particular, the invention is based on the object of providing a method by which the said information can be determined with sufficient safety but without additional sensor technology and correspondingly without additional (cost) effort during manufacture and without additional weight.

[0011] This problem is solved by a method according to claim 1. Advantageous further embodiments of the method according to the invention are the subject-matter of the dependent claims and / or are explained in the following description.

[0012] According to the invention, a method for determining a take-off / landing state of a VTOL aircraft is proposed, according to which a first indicator signal is provided by an inertial measurement unit (IMU), wherein said first indicator signal corresponds to a kinematic of the VTOL aircraft.

[0013] For the purposes of this invention, the term "kinematics" refers to the field of mechanics in which the movement of objects is described purely geometrically using the variables of location, time, speed and acceleration. In other words, it describes how a object moves, which is why kinematics can also be referred to as the theory of motion.

[0014] Advantageously, the inertial measurement device is configured to detect vibrations of the aircraft on the ground, in particular an increase of vibrations on the ground. This detection can be an information within the first indicator signal. This can have the advantage that, for example, the vibrations in the aircraft caused by the increase in thrust by the aircraft's propulsion devices can be used as an indicator for a possible take-off procedure. Conversely, a weakening vibration in the aircraft can be used as an indicator for a possible landing process.

[0015] An indication device that is different, in particular independent, from the inertial measurement device provides a second indicator signal. The second indicator signal is preferably an indicator signal that is independent of, in particular different from, the first indicator signal. The second indicator signal is preferably a type of confirmation signal of the first indicator signal. Furthermore, according to the invention, the first indicator signal and the second indicator signal are processed, in particular logically combined, by a determination device in order to provide a status signal which corresponds to the take- off / landing state of the VTOL aircraft.

[0016] The determination device can be configured as a separate unit, for example as a flight control computer (FCC). However, the determination device can also be part of the inertial measurement device or the indication device. In particular, the determination device can comprise a (micro) processor which is configured and set up in terms of software, firmware and / or hardware in such a way that it can fulfil its intended function.

[0017] Advantageously, once the status signal has been determined, the status signal is outputted, in particular to a (higher-level) flight control unit of the VTOL aircraft, in order to activate / deactivate certain functions depending on the status signal or its signal status. The determination device correspondingly can be configured to output the status signal. For example, the VTOL aircraft can have different displays in flight mode (take-off state) than in the landing state. Conversely, certain maintenance functions or the like that are not available in flight mode may be active or accessible in landing mode, for example.

[0018] The step of providing the status signal can preferably include further sub steps, for which the determination device can be configured accordingly. For example, the determination device can be configured to perform a pre-processing and / or a processing of the first indicator signal and / or the second indicator signal. The pre-processing and / or a processing of the first indicator signal and / or the second indicator signal can be performed during or after receiving the first indicator signal and / or the second indicator signal by the determination device. Reference to the possible output of the status signal has already been made above.

[0019] The approach presented is advantageously based on the use of at least one inertial measurement unit (IMU) with inertial sensors, which are indispensable for (e)VTOL aircraft anyway and are therefore already regularly integrated into the aircraft architecture. They can therefore be used for providing the status signal without additional cost and / or weight. In addition, other signals, such as pilot inputs, for example flight control commands from the pilot, are preferably integrated in order to achieve further protection against incorrect output of the status signal.

[0020] In principle, a weight-on-ground / weight-on-wheels determination process (hereinafter referred to as "WoW determination process"), which may be implemented in the aforementioned determination device, generates a WoW signal (the status signal) that indicates or represents a status of the aircraft (corresponding to a take-off / landing state of the aircraft, i.e. flying or resting on the ground). For example, the WoW signal can read "True" or "Ground" when the aircraft is resting on the ground. In contrast, the WoW signal can be "False" or "INAIR" when the aircraft is flying.

[0021] The terms "aircraft" and "aeroplane" are used here and in the following as synonyms.

[0022] The WoW determination process requires as input at least the first indicator signal, for example a primary vertical velocity, an acceleration and / or a vibration signal, which is determined by means of the inertial measurement device. The first indicator signal correlates with the vertical speed, acceleration and / or vibration of the aircraft. In a preferred embodiment, the first indicator signal is generated by a pre-processing process. The preprocessing process can be implemented in the inertial measurement device.

[0023] In a preferred embodiment, the pre-processing process receives at least two inputs from an inertial measurement unit (i.e. the inertial measurement device), namely an aircraft rotation signal, which may correspond to a rotation of the aircraft in space, and an aircraft acceleration signal, which may correspond to an acceleration, in particular a vertical acceleration of the aircraft in space. Preferably, a vibration of the aircraft can be detected by the pre-processing process.

[0024] In order to adequately take into account a possible drift of these inputs or the corresponding input signals, a change in the barometric altitude and / or the distance to the ground is preferably also taken into account. For example, a barometric and / or a radar altimeter can provide a corresponding (correction) signal for the measured vertical speed. A change in position (i.e. altitude) can also be taken into account via a GPS / GNSS input signal provided by a suitable GPS / GNSS device.

[0025] The pre-processing process can be configured to determine whether a start is imminent. This can be determined, for example, on the basis of rising and / or increased vibrations. Alternatively or additionally, the pre-processing process may include a Kalman filter in order to determine whether the aircraft is ascending. The output of this vertical speed determination process may serve as the input to the WoW determination process, i.e. the primary vertical speed signal (first indicator signal).

[0026] The second indicator signal preferably functions as a confirmation signal and in this context can be a signal for indicating a vertical speed and / or acceleration of the aircraft. The second indicator signal may be provided in the form of a GPS / GNSS signal from the aforementioned GPS / GNSS device. Additionally or alternatively, the second indicator signal may be a signal for indicating a vertical speed and / or acceleration of the aircraft provided by the aforementioned altimeter.

[0027] The second indicator signal can also be a flight control signal. The flight control signal can, for example, be derived from a control input from a pilot and / or an autopilot. The flight control signal may, for example, correspond to an increase in thrust and / or an altitude control signal.

[0028] Additionally or alternatively, the second indicator signal may be a flight phase confirmation signal generated by a respective input means - for example a pilot's flight phase button, i.e. a button or the like used by the pilot to confirm a flight phase (for example "take-off or "landed").

[0029] If the first indicator signal exceeds a predefined threshold value, for example a predefined acceleration and / or vibration threshold value, and at least the second indicator signal also confirms the take-off, for example if a vertical speed is detected and / or a change in altitude is measured, the WoW determination process outputs the status signal or WoW signal "False" or "INAIR", respectively. This indicates that the aircraft has taken off. Conversely, the WoW determination process outputs the WoW signal "True" or "Ground" if the first indicator signal falls below a predefined threshold value, for example a predefined acceleration and / or vibration threshold value, and at least the second indicator signal also indicates that the aircraft has landed. For example, if no vertical speed and / or acceleration is detected and / or a constant altitude is continuously measured, the WoW determination process can output the WoW signal "True" or "Ground".

[0030] In an advantageous embodiment, the second indicator signal is provided by a barometric altimeter - i.e. a Baro-Altimeter - wherein the second indicator signal indicates a change in status. In particular, the second indicator signal can indicate a change in status when the measured ambient air pressure increases or the measured altitude decreases, respectively. This allows to utilise the ground effect that occurs with VTOL aircraft, in particular with eVTOL aircraft, in a particularly advantageous way. The ground effect occurs, for example, when the pilot increases the thrust during take-off. The resulting downwash of the aircraft's propulsion devices, in particular the aircraft's rotors, temporarily increases the local ambient air pressure in the area of the airframe. This temporary increase in ambient air pressure causes the altitude measured by the barometric altimeter to decrease (although the aircraft is still on the ground) before the altitude increases again after take-off in line with the actual altitude.

[0031] The method can also be described mathematically as shown below.

[0032] Yet another further embodiment of the method according to the invention provides that, based on measurement results from n inertial measurement channels of the correspondingly configured inertial measurement device, with n E M, a median solution i is selected from n and used as the output or as one of the outputs of the inertial measurement device in order to provide the first indicator signal. Thereby, n is in particular an odd number in order to enhance the median selection. Each inertial measurement channel i can comprise a three- axis gyroscope with corresponding sensors for measuring rotation rates and a three-axis acceleration sensor with corresponding sensors for measuring a specific force or acceleration. Preferably, for each sensor m,m E [1; 3]in the selected channel i a standard deviation ak mof the last N measured values Xj for a time interval k is calculated, wherein pmis an expected value corresponding to an average sensor signal over the last N measurements or time periods:

[0033] According to the applicant's findings, good results can already be achieved with this procedure, in particular if the aforementioned standard deviation is taken into account when comparing the vertical speed and / or the vibration state with a corresponding, predefined threshold value. In particular, it is possible to compare the determined vertical speed or the determined vibration state with a corresponding threshold value, while at the same time comparing the standard deviation with a separate acceleration threshold value. Both comparisons must preferably provide compatible results such that a valid status signal can be generated.

[0034] In another embodiment of the method according to the invention, a state estimator algorithm, in particular in the form of the optional Kalman filter, can be used in order to estimate the vertical velocity vz of the VTOL aircraft from a state vector X of the VTOL aircraft:

[0035] Here, an acceleration sensor deviation bzalong a vertical plumb line is taken into account as a disturbance variable, wherein this deviation changes slowly over time, for example due to vibrations and temperature hzdenotes a height (in space). The vzis preferably the first time derivative or the rate of change of the height hzmathematically formulated: — = vz. The mentioned disturbance variable along the vertical plumb line (z-axis) should preferably be estimated, as the local gravity is not exactly known and also the accelerometer or sensor (as part of the inertial measurement device) is usually not perfectly calibrated or has a residual bias even after a proper calibration. It is important to emphasise that this deviation occurs in the local navigation reference system and not in the vehicle reference system. It is therefore a deviation along the vertical plumb line. It can be assumed that this deviation changes slowly over time, for example due to vibrations and temperature fluctuations. The real-time estimation of this deviation during the runtime of the method is therefore a positive aspect of this approach and makes the algorithm more robust. Note that the state estimation includes the altitude hzin the navigation reference system, which is also required to determine the vertical speed.

[0036] By taking these interferences into account, the accuracy of the determination and thus the reliability of the method is considerably increased in addition to the robustness.

[0037] In yet another embodiment of the method according to the invention, a temporal change of the state vector X from one time interval k to a time interval k + 1 can be taken into account as follows:

[0038] Whereby AT is a time elapsed since the last discrete change of state, preferably in the range between 1 and 20 ms; azis a specific force measurement of a corresponding acceleration sensor of the inertial measurement device, which has been transformed from an aircraft reference system into a navigation reference system; g is the local gravity from a model or in the form of a constant, for example 9.80665 m / s2.

[0039] The time or time interval AT is typically between 1 and 20 ms and depends on the dynamics of the aircraft and the available computing time or computing power. The specific force measurement must be transformed from the IMU measurement azin the reference system of the aircraft (so-called "body frame b") into the navigation reference system (n) according to the relation az= R ■ af , wherein the matrix R transforms from the current orientation of the aircraft to the navigation reference system.

[0040] The terms nhz, nVz, nbzare noise terms that are preferably modelled and / or empirically adjusted and are specific to the sensors used and the VTOL aircraft.

[0041] In yet another embodiment of the method according to the invention, the height hzcan be measured periodically for each time interval k and fed into the state estimation algorithm in order to prevent a drift of the inertial measurement during the state change. The following applies:

[0042] Here hzis the current height measurement, and nsis an error in the height measurement. The value hzcan be determined in various ways, in particular by means of GNSS, radar or LIDAR, or it can be derived from static air pressure measurements (in millibars) and an assumed standard atmospheric model, in particular according to : wherein p indicates a measured air pressure.

[0043] If several sensors are used for the calculation of hzare used, the different altitude levels are preferably taken into account. For example, an ellipsoidal height from GPS / GNSS measurements should be corrected by an offset if it is used together with the barometric height measurements.

[0044] All of these refinements in turn help to further improve the accuracy of determination. The task mentioned at the beginning is also solved with an aircraft, in particular a VTOL aircraft and most preferably an eVTOL aircraft, according to claim 8. Advantageous further embodiments of the aircraft according to the invention are the subject of the dependent claims and / or are explained in the following description. The above-mentioned features and / or advantages of the method - even if they are disclosed as method features - can be combined with the aircraft or transferred to the aircraft. Vis-versa, the device features disclosed below can also be combined with the method described above.

[0045] The aircraft comprises an inertial measurement unit (IMU) which is configured to provide a first indicator signal which corresponds to the kinematics of the aircraft. The aircraft further comprises an indication device which is different from the inertial measurement device, in particular independent of the inertial measurement device, and which is configured to provide a second indicator signal which is different from the first indicator signal. In addition, the VTOL aircraft according to the invention comprises a determination device which is configured to process the first indicator signal and the second indicator signal, in particular to combine them logically, in order to provide a status signal which corresponds to a take-off / landing state of the VTOL aircraft.

[0046] In an advantageous embodiment of the aircraft according to the invention, the first indicator signal is provided by determining inertial accelerations of the aircraft by the inertial measurement device and subsequently analysing them in order to determine a vertical speed and / or a vibration state of the aircraft and to obtain the first indicator signal therefrom. This is done in particular by comparing the vertical speed and / or the vibration state with a corresponding, predetermined threshold value.

[0047] In a further advantageous embodiment of the aircraft according to the invention, it may accordingly be provided that the inertial measurement device and / or the determination device are configured to determine a vertical speed and / or to determine a vibration state of the VTOL aircraft in order to obtain the first indicator signal therefrom. In particular, the determination can be carried out by comparing the vertical speed and / or the vibration state with a corresponding, predetermined threshold value. The measured inertial accelerations of the aircraft can be used to very accurately detect vibrations in particular, which indicate an imminent take-off of the aircraft.

[0048] In an advantageous further development of the aircraft, the inertial measurement device and / or the determination device are configured to preprocess the first indicator signal in a preprocessing process, in particular to check and / or smooth it. The preprocessing process preferably comprises an iterative processing method, in particular in the form of a Kalman filter.

[0049] In a corresponding, advantageous embodiment of the VTOL aircraft according to the invention, it is provided that the inertial measurement device is connected to a GNSS device and / or to an altimeter, in particular a barometric altimeter, in a signal-communicating manner. The inertial measuring device can be configured to correct a deviation or drift of the inertial measuring device by additionally analysing GNSS data and / or data from the altimeter. It may be provided that the GNSS data and / or the data of an altimeter, in particular of a barometric altimeter, are used as input data for the pre-processing method. This can further increase the accuracy of the evaluation and the certainty of generating the "correct" status signal.

[0050] The term "altimeter" here is used as a synonym for "height measuring device". The abbreviation "GNSS device" also specifically includes "GPS devices".

[0051] The indication device can be configured as at least one device from a group of devices. The group of devices preferably comprises a GNSS device, an altimeter, in particular a barometric altimeter, a device (for example a control stick) for providing the second indicator signal in the form of a flight control signal by a pilot and / or autopilot, and / or a device for providing the second indicator signal in the form of a confirmation signal by a pilot and / or autopilot (for example in the form of a switch, button or push button).

[0052] Preferably, the aircraft comprises at least one further (third) indicator device. The further (third) indication device may be configured to generate a third indicator signal, which is different, preferably independent, from the first indicator signal and the second indicator signal. Additionally or alternatively, the further indicator device may be configured as a device from the above-mentioned group of devices but different from the second indicator device. The allocation of a third, preferably independent, indicator signal, which is generated by the third indication device, can again considerably increase the reliability of the determination.

[0053] The inertial measurement device and / or the determination device can be configured to determine the take-off / landing state of the VTOL aircraft by combining, in particular logically combining, the first indicator signal, the second indicator signal and the third indicator signal. Preferably, in order to reliably determine the take-off / landing status of the VTOL aircraft, it is necessary for all three indicator signals to indicate the same status. This further increases the reliability of the determination.

[0054] Preferably, in a further development of the VTOL aircraft according to the invention, the status signal has an effect on a control system of the VTOL aircraft, i.e. has a direct control effect, as described above. This can include, for example, the activation / deactivation of certain functions, such as a maintenance function or a display configuration.

[0055] Brief description of the drawing

[0056] The different and exemplary features described above can be combined with each other insofar as this is technically sensible and suitable. This applies irrespective of whether the features are described as process features or as device features. Further combinable features, advantages and embodiments of the invention can be seen from the following description of examples of embodiments and with reference to the figures. The figures show

[0057] Figure 1 a schematic representation of an example of a method sequence by means of a block diagram; and

[0058] Figure 2 an example of a VTOL aircraft.

[0059] Embodiments of the invention Figure 1 shows a possible sequence of the procedure using a schematic block diagram. The diagram also includes the means (devices) used to carry out the mehtode.

[0060] The entire arrangement required for carrying out the method is referenced by the reference sign 100; it is a component of an example of an (e)VTOL aircraft 200 according to the invention as shown in Figure 2.

[0061] The arrangement 100 comprises an inertial measurement unit 1 (in short: IMU). Preferably, the inertial measurement unit 1 comprises a plurality of inertial sensors (not shown individually) for measuring accelerations and rotation rates in / around the three spatial directions or in a reference system of the aircraft 200 (see Figure 2).

[0062] In the embodiment shown, the IMU 1 provides two input signals for a downstream preprocessing process 102, namely an aircraft rotation signal 2, which corresponds to a rotation of the aircraft, and an aircraft acceleration signal 3, which corresponds to the acceleration, in particular the vertical acceleration, of the aircraft 200.

[0063] In this way, an inertial measurement unit (IMU) 1 provides at least a first indicator signal that corresponds to the kinematics of the VTOL aircraft.

[0064] In order to adequately take into account a possible drift of these input signals 2, 3, the arrangement 100 shown, initially comprises a (in particular barometric or radar-based) altimeter 4, whereby a change in the barometric altitude and / or the distance to the ground can be taken into account as part of the pre-processing process 102. The altimeter 4 provides a corresponding signal 4a for the vertical speed to the process 102. A change in position can also be indicated additionally or alternatively via a GPS / GNSS device 5 present in the arrangement 100, which GPS / GNSS device 5 provides a corresponding further input signal 5a for the pre-processing method 102.

[0065] In the embodiment shown, the pre-processing process 102 thus generates a first indicator signal 102a corrected in accordance with the signals 4a and / or 5a. The first indicator signal 102a corresponds to a kinematics of the VTOL aircraft, in which in particular the drifting of the input signals 2, 3 has been appropriately taken into account. The pre-processing process 102 can be implemented in the IMU 1 itself (in terms of hardware, software and / or firmware), or it can be set up and executed on a separate, dedicated hardware component.

[0066] The pre-processing process 102 may include a Kalman filter to determine whether the aircraft is climbing or at least vibrating sufficiently to indicate that take-off is imminent. Accordingly, the invention is not limited to determining a vertical speed or acceleration of the aircraft; a (strong) vibration indicating an imminent take-off of the aircraft is also sufficient to generate a corresponding first indicator signal.

[0067] The output respectively the output signal 102a of the pre-processing process 102, namely the first indicator signal 102a, serves as input for a downstream WoW determination process 101.

[0068] In principle, it is also possible to use a vertical speed of the aircraft derived from the position signal of the GPS / GNSS device 5 and / or the altitude measurement signal of the altimeter 4 as a primary vertical speed input signal, i.e. as a first indicator signal - without the preprocessing process 102 or in addition to the pre-processing process 102. This corresponds to the signals 4b or 5b in Figure 1 - in addition to or instead of the signal 102a.

[0069] The method 100 also uses a second indicator signal 4b, 5b, 6a, 7a, which is different from and preferably independent of the first indicator signal 102a, i.e. it was generated by a different device and / or in a different way or is based on different physical conditions. This second indicator signal 4b, 5b, 6a, 7a also serves as input for the WoW determination process 101.

[0070] The WoW determination process 101 can be implemented in a determination device and / or the IMU 1 itself (hardware, software and / or firmware). Alternatively, the WoW determination process 101 can be set up and executed on a separate, dedicated hardware component.

[0071] The WoW determination process 101 evaluates the first indicator signal 102a and the second indicator signal 4b, 5b, 6a, 7a. Based on the evaluation, the WoW determination process 101 generates a status signal 101a (hereinafter also referred to as "WoW signal"), which indicates the take-off / landing state of the aircraft.

[0072] The second indicator signal 4b, 5b, 6a, 7a (hereinafter also referred to as "confirmation signal" 4b, 5b, 6a, 7a) may be a vertical velocity indication provided as a GPS / GNSS signal 5b by the GPS / GNSS device 5. Additionally or alternatively, the confirmation signal 4b, 5b, 6a, 7a may be a vertical velocity indication 4b or a corresponding signal 4b provided by the altimeter 4.

[0073] Alternatively or additionally, the confirmation signal 4b, 5b, 6a, 7a can be generated by a pilot (or autopilot) 8 of the aircraft via further devices 6, 7. The reference symbol 6 denotes a control stick, thrust lever or the like, by means of which the pilot 8 controls a movement of the aircraft and generates a flight control signal 6a for this purpose. The flight control signal 6a may, for example, correspond to an increase in thrust and / or an upward movement of the aircraft. Additionally or alternatively, the confirmation signal is a flight phase confirmation signal 7a, which is generated by an input means 7 (for example, a flight phase button actuated by the pilot 8). Accordingly, the control stick 6 respectively the input means 7 represents a device for providing the second indicator signal in the form of a confirmation signal which is actively generated by a pilot (or autopilot) as such. When the aircraft takes off, the pilot 8 can actuate the input means 7 to indicate that the aircraft has taken off. This applies accordingly to an autopilot or a remote operator.

[0074] Preferably, each of the devices 4-7 can thus function as an indication device in the sense of the present invention and can accordingly provide the second indicator signal 4b, 5b, 6a, 7a.

[0075] If the first indicator signal 102a exceeds a predefined threshold and at least one second indicator signal 4b, 5b, 6a, 7a confirms the take-off of the aircraft, the WoW determination process 101 outputs the WoW signal 101a "False" or "IN AIR". Conversely, the WoW determination process 101 outputs the WoW signal 101a "True" or "Ground" if the first indicator signal 102a falls below a predetermined threshold and at least one second indicator signal 4b, 5b, 6a, 7a confirms the landing of the aircraft. Figure 2 shows an example of an (e)VTOL aircraft 200, in which the method described in Figure 1 can be used in particular.

[0076] The designation "(e)VTOL" stands for an aircraft that can take off and land vertically and is preferably exclusively electrically powered.

[0077] In particular, the (e)VTOL aircraft 200 comprises the arrangement 100 described in detail above with reference to Figure 1 and is thus configured to perform the method 100 described with reference to Figure 1.

[0078] The (e)VTOL aircraft 200 has a plurality of propeller-motor units (only one is explicitly designated by the reference sign 201), which are individually controlled by a flight control or flight control unit 202 of the (e)VTOL aircraft 200 in order to realise a desired flight state of the (e)VTOL aircraft 200.

[0079] The flight control unit 202 receives the status signal 101a as one input signal (among many others), see Figure 1. Thus, the specific status of the (e)VTOL aircraft 200 can have a direct effect on the control system. For example, depending on a state of the status signal 101a, the flight control unit 202 can cause certain functions of the aircraft (maintenance options, display configuration, etc.) to be activated or deactivated.

[0080] In particular, the status signal 101a may be used solely for the purpose of an indication to the pilot or an operator (for example, as an indication to inform the pilot on board or a remote operator and others involved in the flight, whether the aircraft is on the ground, in the air or has landed).

[0081] The status signal 101a may also be used for logging purposes, whereby a specific event prior to take-off or landing may be used to identify relevant flight log data or to correlate different flight log data with each other.

[0082] The status signal 101a can be actively used as an input for the flight control logic (in the flight control unit 202), for example to activate and deactivate parts of the flight controller that behave in an integrating manner (control integrators, reference model integrators, sensor fusion integrators, etc.), or to reset relevant measurements or internal states before take-off and after landing.

[0083] Finally, the status signal 101a can also be used in algorithms at a higher level, for example for automatic take-off and landing or for carrying out various logic processes that must take place before take-off from the ground, after take-off in the air and after landing on the ground as soon as the aircraft has landed again.

Claims

Patent Claims1. Method (100) for determining a takc-off / landing state of a VTOL aircraft (200), according to which(a) a first indicator signal (102a) corresponding to a kinematic of the VTOL aircraft (200) is provided by an inertial measuring device (1);(b) a second indicator signal (4b) different from the first indicator signal (102a) is provided by an indication device (4) different from the inertial measuring device (1); and(c) a determining device (101) processes, in particular logically combines, the first indicator signal (102a) and the second indicator signal (4b, 5b, 6a, 7a), to provide a status signal (101a), which correlates with the take-off / landing state of the VTOL aircraft (200), wherein(d) the second indicator signal (4b) is provided by a Baro-Altimeter (4), and the second indicator signal (4b) indicates a take-off state of the VTOL aircraft (200) when the ambient air pressure measured by the Baro-Altimeter (4) increases or the altitude measured by the Baro-Altimeter (4) decreases.

2. Method (100) according to claim 1, wherein the first indicator signal (102a) is provided by determining inertial accelerations of the VTOL aircraft (200) by the inertial measurement device (1) and subsequently analysing them to determine a vertical acceleration and / or a vibration state of the VTOL aircraft (200) to obtain the first indicator signal (102a) therefrom, in particular by comparing the vertical acceleration and / or the vibration state with a corresponding predetermined threshold value.

3. Method (100) according to one of the preceding claims, wherein a pre-processing process (102) is configured to determine the first indicator signal (102a) on the basis of rising and / or increased vibrations of the VTOL aircraft (200).

4. Method (100) according to one of the preceding claims, in which a deviation or drift of the inertial measurement device (1) is corrected on the basis of GNSS data and / or data from an altimeter (4), in particular a Baro-Altimeter (4).

5. Method (100) according to one of the preceding claims, wherein a third indicator signal (4b, 5b, 6a, 7a) different from the first indicator signal (102a) and different from the second indicator signal (4b, 5b, 6a, 7a), preferably independent from the first indicator signal (102a) and independent from the second indicator signal (4b, 5b, 6a, 7a), is provided by a second indication device (4, 5, 6, 7) different from the inertial measuring device (1) and different from the first indication device (4, 5, 6, 7).

6. Methode (100) according to claim 5, wherein the third indicator signal (6a) is a flight control signal (6a) derived from a control input from a pilot (8) and / or an autopilot, in particular an increase in a thrust and / or an altitude control signal (6a).

7. Methode (100) according to claim 5, wherein the third indicator signal (7a) is a flight phase confirmation signal (7a) generated by a respective input device (7), in particular a pilot's flight phase button (7).

8. Aircraft (200), preferably eVTOL aircraft (200), said aircraft (200) comprising:(a) an inertial measurement device (1) configured to provide a first indicator signal (102a) corresponding to the kinematics of the VTOL aircraft (200),(b) an indication device (4) which is different from the inertial measuring device ( 1 ) and in particular independent of the inertial measuring device (1), and which is configured to provide a second indicator signal (4b, 5b, 6a, 7a) which is different from the first indicator signal (102a), and(c) a determination device (101) which is configured to process the first indicator signal (102a) and the second indicator signal (4b, 5b, 6a, 7a), in particular to combine them logically, in order to provide a status signal (101a) which correlates with a take-off / landing state of the VTOL aircraft (200), wherein(d) the indication device (4) is a Baro-Altimeter (4) and the Baro- Altimeter (4) is configured to provide the second indicator signal (4b) indicating a take-off state of the VTOL aircraft (200) when the ambient air pressure measured by the BaroAltimeter (4) increases or the altitude measured by the Baro-Altimeter (4) decreases.

9. Aircraft (200) according to claim 8, wherein the indicator device (4) is a first indicator device (4) and the aircraft comprises a second indicator device (5-7) different from the first indicator device (4) and different from the inertial measurement device (1), wherein the second indicator device (5-7) is configured to generate a third indicator signal (5b, 6a, 7a) different from the first indicator signal (102b) and different from the second indicator signal (4b), preferably independent from the first indicator signal (102b) and independent from the second indicator signal (4b).

10. Aircraft (200) according to claim 9, wherein the second indication device (5-7) is configured as:(a) a GNSS device (5),(b) a device (6) for providing the second indicator signal (4b, 5b, 6a, 7a) in the form of a flight control signal (6a) by a pilot (8) and / or autopilot, and / or(c) a device (7) for providing the second indicator signal (4b, 5b, 6a, 7a) in the form of a confirmation signal by a pilot (8) and / or autopilot.

11. Aircraft (200) according to one of the claims 8 to 10, wherein the inertial measurement device (1) is connected to a GNSS device (5) and / or to an altimeter (4), in particular a Baro-Altimeter (4), in a signal-communicating manner, and is configured to correct a deviation or a drift of the inertial measurement device (1) by additional evaluation of GNSS data and / or of data of the altimeter (4).

12. Aircraft (200) according to claim 11, wherein the inertial measurement device (1) and / or the determination device (101) are configured to determine the take-off / landing state of the aircraft (200) by combining, in particular logically combining, the firstindicator signal , the second indicator signal (4b, 5b, 6a, 7a) and the third indicator signal (4b, 5b, 6a, 7a) and to provide the corresponding status signal (101a).

13. Aircraft (200) according to one of the claims 8 to 12, wherein the aircraft comprises a flight controller (202) configured to receive the status signal (101a) and to change, in particular to limit, the control capabilities of the aircraft (200) based on the status signal (101a).

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