Method and assistance system for assisting pilot in controlling aircraft, and aircraft

Abstract

A method of assisting a pilot (26) in controlling an aircraft (20) having a plurality of lift-generating propulsion devices (21), the method comprising the following method steps: for each of the following, calculating instantaneous control limits (3, 4): control of the aircraft about its roll axis (x), control of the aircraft about its pitch axis (y), control of the aircraft about its yaw axis (z), and control of the total thrust T of all propulsion devices (21); and displaying the calculated control limits (3, 4) by means of a display device (29).

Description

Technical Field

[0001] The invention relates to a method and an assistance system for assisting a pilot in controlling an aircraft having a plurality of lift-generating propulsion devices, and to an aircraft having such an assistance system. Background Art

[0002] Aircraft with fly-by-wire controls—particularly those with electric propulsion and eVTOL mechanisms—typically do not provide direct tactile feedback that allows the pilot to determine whether a requested control input can be executed with full power or only with partial power (or not at all). Even if a control input can be fully executed, i.e., if the aircraft can achieve the flight state requested by the pilot, it may not be obvious to the pilot how much control margin remains in a given situation. In other words, the pilot may not be aware of whether or how much control margin remains to control the aircraft.

[0003] The use of tactile feedback, in particular tactile feedback via the control stick of an aircraft, is known from the prior art. Here, an actuator causes force feedback that is transmitted from the control stick to the pilot.

[0004] However, in eVTOL aircraft, in particular in aircraft with a multi-rotor design and / or with a large number of propulsion devices with fixed and / or adjustable pitch or angle of attack for each propulsion device, there is no clear independence between the control axes. For example, in hovering mode, a control input related to the roll axis or the pitch axis can significantly reduce the control reserve along the yaw axis than on the roll and pitch axes. This is caused by the fact that such an aircraft can have N propulsion devices in the form of actuators (rotors or propellers and propulsion engines; ), each of the propulsion devices can be controlled by adjusting the corresponding rotor revolutions per minute (RPM). The sum of the thrust and torque generated by these N actuators and available for action on the aircraft fuselage is used to control and stabilize the aircraft. Therefore, no propulsion device can generate unlimited thrust and torque. There is also a lower limitation of control, because it is undesirable to completely shut down individual actuators during flight. Although these limits for the individual actuators are relevant control limits from a control theory point of view, these limits are of low benefit to the pilot in terms of command, especially because saturation of individual actuators does not mean that the control limits of the aircraft as a whole have been reached. This is due to the fact that the required workload can be distributed over all available actuators.

[0005] Finally, the force feedback known from the prior art can be ambiguous and confusing for the pilot of an eVTOL aircraft. In terms of flight safety, this represents an intolerable inconsistency in human-machine interaction.

[0006] Regardless of the above disadvantages, the introduction of active feedback using actuators inevitably increases the weight and complexity of the corresponding aircraft. In addition, the large number of additional components also increases the potential of possible error sources. Summary of the invention

[0007] An object of the present invention is to meet the above needs of the prior art and / or to eliminate the associated disadvantages. In particular, an object of the present invention is to provide a method, an assistance system and an aircraft with which flight safety is improved in the interaction between the pilot and the aircraft without having to increase the total weight of the aircraft.

[0008] This object is solved by a method according to the invention for assisting a pilot in controlling an aircraft having a plurality of lift-generating propulsion devices. The method comprises the following method steps: (a) calculating instantaneous control limits for each of: (a1) the control of the aircraft about its roll axis, (a2) the control of the aircraft about its pitch axis, (a3) ​​the control of the aircraft about its yaw axis, and (a4) the control of the total thrust of all propulsion devices; and (b) displaying the calculated control limits to the pilot by means of a display device. Advantageous further embodiments of the method according to the invention are explained in the following description.

[0009] To solve the above-mentioned purpose, according to the present invention, a method suitable for assisting a pilot in controlling an aircraft having a plurality of lift-generating propulsion devices is proposed. In other words, this method is preferably applicable to an aircraft having a plurality of propulsion devices (in particular a plurality of rotors). The propulsion device is configured to generate lift in such a way that the aircraft can take off and / or land (e.g., vertical take-off and / or vertical landing). Depending on the inclination angle of the propulsion device relative to the aircraft and / or the inclination angle of the aircraft in space, the propulsion device can also be configured to generate forward drive. For example, the aircraft may be a multi-rotor helicopter having several rotors, in particular an eVTOL. Preferably, each of the propulsion devices has an unchangeable inclination angle relative to the aircraft.

[0010] According to the invention, the method comprises the method step of calculating instantaneous control limits of the aircraft.For example, the calculation may be performed by a calculation device.

[0011] For the purposes of the present invention, the term "control limits" refers to physical limits for controlling an aircraft. This means, for example, that control of the aircraft outside the control limits is physically impossible and / or results in a crash of the aircraft. In particular, the control limits may correspond to flight states that are physically achievable by the aircraft. For example, the control limits may be limits on a maximum roll angle about the roll axis of the aircraft, a maximum pitch angle about the pitch axis of the aircraft, a maximum yaw angle about the yaw axis of the aircraft, and / or a maximum total thrust. Alternatively or additionally, the control limits may be configured as limits on a roll rate, a pitch rate, and / or a yaw rate around the corresponding aircraft axis. Other forms of limits, such as limits on a maximum rotational acceleration and / or a maximum torque around the corresponding aircraft axis, are also possible as control limits.

[0012] For the purposes of the present invention, the term "instantaneous" is understood to mean the current state in terms of time. This means, for example, that the result of an instantaneous calculation may deviate from the result of the same calculation in the past and / or in the future (particularly in the past and / or future time steps).

[0013] According to the invention, the instantaneous control limits are calculated in each case for: the control of the aircraft about its roll axis, the control of the aircraft about its pitch axis, the control of the aircraft about its yaw axis and the control of the total thrust of all propulsion means. Thus, the physical fact is taken into account according to which, for an aircraft with several lift-generating propulsion means (in particular an eVTOL, preferably in the form of a multirotor helicopter), all the above-mentioned control parameters influence each other or are dependent on each other. The control of the aircraft about its roll axis, its pitch axis and / or its yaw axis may depend in particular on the arrangement and / or the instantaneous thrust output of the individual propulsion means.

[0014] In a further method step of the method according to the invention, the calculated control limits are displayed by a display device. For example, the display can take the form of a scale. By displaying the calculated control limits, these calculated control limits can be made accessible to the pilot by technical means.

[0015] The technical contribution produced by the present invention improves the human-machine interaction between the pilot and the aircraft in such a way that the pilot is always aware of the physical performance limits of the aircraft to be controlled. The method according to the invention has the following advantageous effect: the pilot is always informed of the current limitations or control limits of the aircraft by the above-mentioned technical measures. This enables the pilot to always control the aircraft within the physical capabilities of the aircraft. In particular, based on the displayed calculated control limits, the pilot is always able to control the aircraft within the physical capabilities of the aircraft. In other words, the method according to the invention avoids operating the aircraft outside the physical capabilities of the aircraft, which at the same time reduces the risk of potential crashes. Therefore, among other things, the method according to the invention has the advantage of improving flight safety without having to increase the total weight of the aircraft through additional components.

[0016] In an exemplary embodiment of the method according to the invention, the control limits are calculated based on the current flight state of the aircraft. Thus, for example, the current position of the aircraft in space and / or the airflow towards the aircraft may be detected by sensors. Alternatively or additionally, the current control limits may be calculated based on the control system of the aircraft.

[0017] In particular, the term "control of the aircraft" may refer to the control of the aircraft about its roll axis, about its pitch axis, about its yaw axis and / or about the control of the total thrust of all propulsion devices. Independently of the above, the instantaneous control limits may be calculated based on the instantaneous control inputs of the pilot and / or based on the instantaneous control signals. For example, the control signal may be a signal from the flight control computer to the propulsion devices. In particular, the target rotation speed of the rotor and / or the control of the propulsion devices corresponding to the target rotation speed of the rotor may be control signals within the meaning of the present invention.

[0018] The above embodiment advantageously has the effect that all current control parameters are taken into account when calculating the current control limits. Among other things, this has the advantage that the physically existing flight state of the aircraft can be recorded particularly accurately by technical means to increase the accuracy of the calculated control limits.

[0019] According to another exemplary embodiment, the calculation of the control limits is performed dynamically. In other words, the calculation of the control limits is performed repeatedly over time. Preferably, the calculation of the control limits is performed periodically, for example repeatedly at predefined time intervals. Preferably, the time intervals between the individual calculation steps are chosen so short that the calculation of the control limits is performed in real time.

[0020] The dynamic (in particular periodic) calculation of the control limits advantageously ensures that the calculated control limits always correspond to the current flight state of the aircraft. This has the advantage that the control limits provided by the method correspond sufficiently accurately to the current maximum physically achievable flight state of the aircraft. As a result, flight safety can be further increased.

[0021] Preferably, each of the calculated control limits is displayed separately. In other words, each of the calculated control limits is displayed separately from the other calculated control limits, in particular separately at a distance from the other calculated control limits. Such a display advantageously has the effect that the pilot can particularly easily identify the individual control limits. This can have the advantage of further increasing flight safety. Alternatively, it is also conceivable that the calculated control limits are displayed at least partially overlapping. This has the advantage that less display area is required for the display of the calculated control limits. In this respect, in addition to the calculated control limits, further information can be displayed.

[0022] In another exemplary embodiment, a neutral control value may be displayed. For the purposes of the present invention, the term "neutral control value" is understood to mean a neutral output value of the corresponding control parameter. For example, a neutral control value for controlling an aircraft about its roll axis is a roll angle of 0°. The same may apply to a neutral control value for controlling an aircraft about its pitch axis and / or yaw axis. Alternatively or additionally, a neutral control value for controlling an aircraft about the corresponding aircraft axis may also be a rotation speed of 0° / s, a speed of 0° / s, a speed of 0° / s, a speed of 0° / s, a speed of 0° / s, a speed of 0° / s, a speed of 0° / s 2 The neutral control value for the total thrust of all propulsion devices may be 0 Newtons (N). In other words, when the neutral control value exists, the propulsion devices generate no lift or negligible lift.

[0023] Preferably, the calculated control limits are each displayed with respect to a corresponding neutral control value. For example, control limits in which the control of the aircraft is not completely limited or is only slightly limited can be displayed further away from the displayed neutral control value than control limits in which the control of the aircraft is strictly limited. Such a display can advantageously ensure that the pilot can identify the individual control limits particularly easily. This can have the advantage of further improving flight safety by providing the pilot with a better overview of the control limits of the aircraft. In other words, the resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in such a way that the pilot is always aware of the physical performance limits with respect to the neutral control value of the aircraft to be controlled.

[0024] In another exemplary embodiment of the method, for at least one control limit, the area within the corresponding control limit can be visually displayed differently from the area outside the corresponding control limit. Preferably, the area within each of the control limits is visually indicated differently with respect to the area outside the corresponding control limit. For example, visual differentiation can be achieved by using different colors and / or different graphic structures. For example, the area within the control limit can be displayed in green color. The area outside the control limit can be displayed in black. The visually differentiated display can advantageously ensure that the pilot can particularly easily identify the control area within the individual control limits. Therefore, this can further improve flight safety by providing the pilot with a better overview of the control limits of the aircraft. In other words, the resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in a way that the pilot can more easily identify the physical performance limitations of the aircraft.

[0025] At least one of the control limits may have an upper control limit and a lower control limit. Preferably, all control limits each comprise an upper control limit and a lower control limit.

[0026] In particular, the upper control limit may be a maximum control value. For example, the upper control limit for controlling an aircraft around its roll axis is the maximum roll angle that the aircraft can achieve. The lower control limit is preferably the maximum roll angle in the opposite direction. The same may also apply to the upper and lower control limits for the pitch axis and / or yaw axis of the aircraft. Alternatively or additionally, the upper control limit for the corresponding aircraft axis may also be the maximum rotational speed in a first rotational direction, the maximum rotational acceleration in a first rotational direction and / or the maximum torque in a first direction. With respect to the corresponding aircraft axis, the lower control limit may be the maximum rotational speed in a second rotational direction opposite to the first rotational direction. It is also conceivable that the lower control limit for the corresponding aircraft axis is the maximum rotational acceleration in a second rotational direction and / or the maximum torque in a second direction. With respect to the total thrust of all propulsion devices, the upper control limit may correspond to the maximum thrust. In other words, the propulsion device generates the maximum possible lift at the upper control limit.

[0027] Preferably, the upper control limit and / or the lower control limit for at least one of the control limits are visually emphasized when displayed. Particularly preferably, for all control limits, the corresponding upper control limit and / or the lower control limit are highlighted. For example, the upper control limit and the lower control limit can be visually highlighted using a signal color such as red and / or a particularly obvious graphic display such as flashing. Alternatively or additionally, the upper control limit and the lower control limit can also be indicated by displaying a numerical value, in particular dynamically changing the numerical value. The visual highlighting can advantageously have the effect that the pilot can particularly easily identify the corresponding control limit. Therefore, this can further improve flight safety by providing the pilot with a better overview of the control limits of the aircraft. In other words, the resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in a way that the pilot is always aware of the physical performance limits of the aircraft.

[0028] Regardless of the above, the upper and lower control limits may be displayed as parallel lines. Alternatively or additionally, the upper and lower control limits may be displayed at a distance relative to the corresponding neutral control value. Preferably, the distance between the control limit and the neutral control value varies according to the calculated instantaneous control limit.

[0029] In another exemplary embodiment of the method, instantaneous control values ​​are displayed for the control of the aircraft about its roll axis, the control of the aircraft about its pitch axis, the control of the aircraft about its yaw axis and / or the control of the total thrust of all propulsion devices. This can advantageously enable the pilot to evaluate his current control input relative to the calculated control limits. In other words, such an embodiment uses technical means to inform the pilot of the relationship between his control input and the physically possible flight control of the aircraft. This can have the advantage of further improving flight safety by providing the pilot with a better overview of the control limits of the aircraft. In other words, the resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in a way that makes the pilot aware of the physical performance limits of the instantaneous control values ​​of the aircraft.

[0030] In an advantageous further development of the above-mentioned embodiment, the display of the instantaneous control value is changed as soon as the corresponding instantaneous control value reaches the calculated control limit. This allows visually signaling to the pilot by technical means that the pilot has exhausted the physically possible control potential of the aircraft with his control inputs. Alternatively or additionally, the technical means can also provide the pilot with tactile and / or acoustic signals.

[0031] Another advantageous further development of the method according to the invention provides for the use of a graphic mark to indicate the instantaneous control value of the control component / control parameter in question (e.g., the control of the aircraft around its roll axis, pitch axis, yaw axis and / or total thrust). The control value of the component can be displayed dynamically and digitally above or below, depending on the position of the graphic mark. The control value of the component can be displayed in conjunction with the upper and lower limits of the displayed control limits. The color of the mark (e.g., an arrow or a triangle) is preferably changed according to the distance of the associated value from the instantaneous control limit. Thus, when the current control limit is reached, the display color of the mark can correspond to the display color of the corresponding control limit, for example, being changed to red, while the display color beyond this is, for example, green. When approaching the control limit, intermediate colors, such as yellow and / or orange, can also be used. Most preferably, when the current control limit is reached, an audible, visual and / or tactile alarm is also triggered. In this case, the mark itself can also be displayed as flashing. This can have the advantage of further improving flight safety by providing the pilot with a better overview of the control limits of the aircraft. In other words, the resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in such a way that the pilot is always aware of the physical performance limits of the aircraft to be controlled. In an exemplary further development of the method, displays for the individual control limits can be arranged around a central display area. The central display area can advantageously be used in a conventional manner to display instruments of the aircraft, etc. In particular, the so-called "basic T" familiar to the pilot - preferably including displays for an artificial horizon, an altimeter, an airspeed indicator and a gyroscope - can be displayed in the central display area in order to (also) provide the pilot with a cockpit design familiar from other aircraft. This can make flying the aircraft even easier.

[0032] In another exemplary embodiment of the method, the control of the aircraft can be described by a vector. In particular, the vector may correspond to the current flight state of the aircraft. Preferably, the vector comprises four components, namely three components of the torque around the corresponding aircraft axis and the total thrust of all propulsion devices. The three components constituting the torque may depend on the arrangement and / or the instantaneous thrust of the individual propulsion devices. In order to calculate the control limits, the instantaneous limit of each of the four components of the vector is specifically determined.

[0033] For an exemplary calculation of the vectors, the three-dimensional torque vector τ (roll, pitch and yaw torques in Newton meters) acting on the aircraft fuselage and the total thrust T (in Newtons) generated by all propulsion devices as a whole in the rotor plane can be mathematically related to the individual actuator speed commands via the so-called motor matrix M:

[0034]

[0035] In the sense of this invention, a "vector" comprises an instantaneous single value for each control parameter for a specific timestamp. For example, at the instantaneous timestamp t0, the vector γ may comprise specific values ​​of control parameters for controlling the aircraft around its roll axis, for controlling the aircraft around its pitch axis, for controlling the aircraft around its yaw axis and for controlling the total thrust of all propulsion devices. A specific value of a control parameter for controlling the aircraft around an axis may have units degrees, degrees / s, degrees / s 2 or radians, radians / s or radians / s 2 A particular value of a control parameter for controlling the total thrust of all propulsion devices may have the unit Newton (N).

[0036] At time stamp t1 , which is subsequent to time stamp t0 , the value of the control parameter within vector γ may be different from the value of the control parameter within vector γ at t0 .

[0037] Vector RPM cmd ——RPM min ≤RPM cmd ≤RPM max - may contain a speed command (e.g. in revolutions per minute) and preferably has dimension N (N = number of propulsion devices), the motor matrix M is a 4×N matrix, and the vector γ has dimension 4 (containing the three-dimensional torque vector τ and the total thrust T). Vector RPM cmd The square of here means squaring element by element. The motor matrix M preferably depends on the position of the individual motors (or the corresponding rotors) in the aircraft and the torque and thrust that can be generated by the motors / rotors. Alternatively or additionally, the motor matrix M can also depend on the health of the individual motors. The health of the individual motors can be represented by weights with values ​​ranging, for example, between [0, 1]. It should be noted that these values ​​can vary depending on a variety of factors such as air density or (electrical) voltage. In general, however, the motor matrix M for a given condition can be approximated by a constant matrix. In the following, it is assumed that a suitable matrix M is given or known.

[0038] As the lower RPM limit RPM min or upper RPM limit RPM maxAs a result, the set of all possible permutations of the vector γ is enclosed by a 4-dimensional convex hull, a so-called 4D polyhedron, which defines the control limits of the aircraft. In other words, the 4D polyhedron defines the control volume of the control limits / parameters. For a stable, controlled aircraft, the control parameters must be within this control volume. If the control parameters (torque in each aircraft axis or total thrust) drop below or exceed the control volume, a degradation in the performance of the aircraft occurs. The display of the control parameters can indicate a stable or unstable operating state of the entire aircraft system or flight control system. This helps the pilot to take the necessary actions to stabilize the aircraft again or to bring the aircraft back within the 4D polyhedron. For example, the pilot can manually recover the aircraft using the pilot control stick and thrust regulator, or the pilot can press a recovery button so that the aircraft can automatically recover its control state. An advantageous embodiment of the present invention now allows this 4D polyhedron to be approximated by a 4D hyperellipsoid with the best possible fit (for example, according to the least squares method). For illustration, reference is made to the following figures (in particular Figure 1 ) description.

[0039] The constraint of the vector γ on this 4D hyperellipsoid can be expressed as a quadratic inequality:

[0040] (γ-γ0) T ·A·(Y-Y0)≤1

[0041] in

[0042]

[0043] γ0=(L0,M0,N0,T0) T

[0044] and a scalar value L specifying the length of the semi-axis of the hyperellipsoid max 、M max 、N max and T max , and the scalar values ​​L0, M0, N0, and T0 that define the center of the hyperellipsoid.

[0045] It is important to note that the maximum and center values ​​of the ellipsoid axes are constant, while the current limits along each axis are highly dynamic and constantly changing, depending on the current commanded (by the pilot) 4D vector γ Cmd A good example is a situation where the maximum thrust command leaves no more room for roll and pitch commands or corresponding maneuvers, because all motors are already running at full speed and there is no more available speed difference for transferring roll or pitch moments to the aircraft body.

[0046] One possible aspect of the invention now consists in calculating the mentioned current control limits (for example on the basis of the hyperellipsoid representation explained above), and using them for display. Basically, the aim is to dynamically display to the pilot the current remaining control margin for each of the four available degrees of freedom (corresponding here to roll, pitch, yaw and lift / total thrust). For a given γ at any period, i.e. within a given time interval, Cmd , control limits for all axes can be calculated epoch by epoch. These dynamically calculated control limits can then be displayed to the pilot.

[0047] Two separate control limits (upper and lower) for each of the axes are obtained by determining Cmd The two intersection points of the line along the control axis with the superellipsoid in the 4-dimensional torque-thrust space.

[0048] Assuming τ = γ - γ0, the intersection of the ellipsoids along the search direction v will be found for a general ratio κ. Then the following applies:

[0049] (τ+αv) T A(τ+αv)=κ.

[0050] This leads to solutions of the following type:

[0051]

[0052] In order to find all solutions, if all unit directions are selected successively for the search direction v (i.e. v = (1, 0, 0, 0) T 、(0,1,0,0) T etc.) and additionally setting κ=1, the calculation is simplified as follows (with a slight abuse of notation):

[0053] Dynamic upper control limits for all four axes and lower control limits That is, the instantaneous control limits of the vector γ with respect to each of the four components (axes of the ellipsoid) can be calculated as follows:

[0054] c=1-(γ-γ0) T A (Y-Y0)∈[0,1],

[0055]

[0056] From this γ max =(L max , M max , N max , T max ) T and(.) 2means that the square is taken element by element, and the square root is also taken element by element. In other words, (.) 2 This involves taking each corresponding pair of elements from the two vectors γ and γ0, computing their difference and then squaring the result of each difference. As described in detail above, the dynamically determined control limits may then be graphically displayed to the pilot.

[0057] The object of the invention formulated at the outset is also solved with an assistance system according to the invention for assisting a pilot in controlling an aircraft. The assistance system comprises (a) a calculation device for calculating instantaneous control limits for each of: (a1) the control of the aircraft about its roll axis, (a2) the control of the aircraft about its pitch axis, (a3) ​​the control of the aircraft about its yaw axis, and (a4) the control of the total thrust of all propulsion devices, and (b) a display device for displaying the calculated control limits to the pilot. Advantageous further developments of the assistance system according to the invention are explained in the following description.

[0058] The auxiliary system according to the invention implements the same inventive concept as one of the above methods. Specifically, the auxiliary system according to the invention is configured to perform one of the above methods. In this regard, all of the above features, combinations of features and advantages may also be combined with or applied to the auxiliary system.

[0059] The assistance system is specifically configured to support the pilot in controlling the aircraft. The assistance system comprises at least one computing device and one display device. The computing device and the display device are preferably connected to each other in a signal communication manner. Independently of the above, the computing device and the display device can be spatially separated from each other or can be formed in a common device.

[0060] According to the invention, the computing device is configured to compute instantaneous control limits for controlling the aircraft about its roll axis, for controlling the aircraft about its pitch axis, for controlling the aircraft about its yaw axis and for controlling the total thrust of all propulsion devices. The computing device may be, for example, a processor and / or a computer.

[0061] The display device is configured to display the calculated control limits, in particular the control limits calculated by the calculation device. The display device may be, for example, a display, in particular a heads-up display (HUD) and / or a touch panel with display functionality.

[0062] In another exemplary development of the assistance system according to the invention, the assistance system comprises an input device. Preferably, the input device is configured as a pilot control stick (PCS). The input device may be directly or indirectly connected and / or connectable to the computing device in a signal communication manner. For example, the input device may be indirectly connected to the computing device via one or more other devices. Regardless of the above, the input device may be directly or indirectly connected and / or connectable to the display device in a signal communication manner. For example, the input device may be indirectly connected to the display device via one or more other devices. Preferably, the input device is connected and / or connectable to the computing device in a signal communication manner. For its part, the computing device may be connected and / or connectable to the display device in a signal communication manner. For example, the input device may be configured to receive a control command of the pilot. Preferably, the control command of the pilot received by the input device is then provided to the computing device as a control input, in particular as a signal corresponding to the control input. The control command of the pilot may be measured from a variety of sensors associated with the pilot control stick (PCS), the sensor being, for example, a force sensor or a position sensor or any other type, wherein these sensor signals are then processed to generate a control input by the computing device.

[0063] The computing device may transmit the control input to the display device in a modified and / or unmodified form. As part of the control method, the computing device may modify, in particular edit and / or process the control input. For example, the control method may have a pseudo-control, such that the control method represents a mapping specification from the control input and the state to the pseudo-control.

[0064] The object of the invention formulated at the outset is also achieved with an aircraft according to the invention having an auxiliary system as described above. The aircraft comprises a plurality of lift-generating propulsion devices. Advantageous further embodiments of the aircraft according to the invention are explained in the following description.

[0065] The aircraft according to the invention implements the same inventive concept as one of the above-described methods and / or one of the above-described auxiliary systems. The aircraft according to the invention preferably comprises one of the above-described auxiliary systems. In this respect, all of the above-described features, combinations of features and advantages may also be implemented / combined with or by the aircraft.

[0066] According to the invention, in addition to one of the above-mentioned auxiliary systems, the aircraft comprises a plurality of lift generating propulsion devices. At least one of the plurality of lift generating propulsion devices comprises a rotor and a motor for driving the rotor. Preferably, each of the plurality of lift generating propulsion devices comprises a rotor and a motor for driving the corresponding rotor.

[0067] In an exemplary embodiment of an aircraft, the propulsion device is arranged and / or configured on the aircraft in a manner such that the propulsion device generates the lift required to maintain the aircraft in a substantially stable hovering position. In other words, the propulsion device is arranged and / or configured on the aircraft in a manner such that the propulsion device can generate vertical lift.

[0068] The invention and advantageous further embodiments of the invention can also be described by way of example in the following aspects. The features listed in these aspects can be combined with the features described above.

[0069] Aspect 1 is a method for assisting a pilot in controlling an aircraft having a plurality of lift generating propulsion devices, the method comprising the following method steps:

[0070] Calculate the instantaneous control limits for each of the following:

[0071] control of said aircraft about its roll axis,

[0072] control of said aircraft about its pitch axis,

[0073] control of the aircraft about its yaw axis, and

[0074] Control of the total thrust T of all propulsion units, and

[0075] The calculated control limits are displayed via a display device.

[0076] Aspect 2 is a method according to Aspect 1, wherein the calculation of the control limits is performed based on the instantaneous flight state of the aircraft and / or the instantaneous control of the aircraft, preferably based on the control of the aircraft around its roll axis, the control of the aircraft around its pitch axis, the control of the aircraft around its yaw axis and the control of the total thrust T of all propulsion devices.

[0077] Aspect 3 A method according to one of the preceding aspects, wherein the calculation of the control limits is performed dynamically, preferably periodically.

[0078] Aspect 4: A method according to one of the preceding aspects, wherein the control limits correspond to physically achievable flight states of the aircraft.

[0079] Aspect 5 A method according to any one of the preceding aspects, wherein each of the calculated control limits is displayed separately from the corresponding other calculated control limits.

[0080] Aspect 6 A method according to any one of the preceding aspects, wherein at least one of the control limits is displayed relative to a neutral control value.

[0081] Aspect 7 A method according to one of the preceding aspects, wherein for at least one control limit, preferably for all control limits, an area within a corresponding control limit is visually displayed differently from an area outside the corresponding control limit.

[0082] Aspect 8 A method according to one of the preceding aspects, wherein at least one of the control limits, preferably all of the control limits, has an upper control limit and a lower control limit.

[0083] Aspect 9. A method according to aspect 8, wherein for at least one control limit, preferably for all control limits, the upper control limit and / or the lower control limit is highlighted in a graphical manner, preferably by a signal color.

[0084] Aspect 10: A method according to one of aspects 8 or 9, wherein the upper control limit and the lower control limit are shown as parallel lines within a display field.

[0085] Aspect 11 A method according to one of the preceding aspects, wherein the instantaneous control value is displayed for control of the aircraft about its roll axis, for control of the aircraft about its pitch axis, for control of the aircraft about its yaw axis and / or for control of the total thrust T of all propulsion devices.

[0086] Aspect 12: A method according to aspect 11, wherein the graphical representation of the instantaneous control value is changed as soon as the instantaneous control value reaches the corresponding control limit.

[0087] Aspect 13 A method according to one of the preceding aspects, wherein the control of the aircraft is described by a vector comprising four components, namely three components of torque about the corresponding aircraft axes and the total thrust, wherein the three components of torque depend on the arrangement of the individual propulsion devices and the instantaneous thrust, and the instantaneous limits of the vector with respect to each of the four components are determined to calculate the control limits.

[0088] Aspect 14 is an auxiliary system for assisting a pilot in controlling an aircraft, the auxiliary system comprising:

[0089] Calculation means for calculating the instantaneous control limit for each of:

[0090] control of said aircraft about its roll axis,

[0091] control of said aircraft about its pitch axis,

[0092] control of the aircraft about its yaw axis, and

[0093] Control of the total thrust T of all propulsion units, and

[0094] A display device is provided for displaying the calculated control limits.

[0095] Aspect 15: The assistance system according to Aspect 14, wherein the assistance system is configured to perform the method according to any one of Aspects 1 to 13.

[0096] Aspect 16: The assistance system according to one of Aspects 14 or 15, wherein the computing device and the display device are connected to each other in a signal communication manner.

[0097] Aspect 17 An assistance system according to any one of Aspects 14 to 16, wherein the assistance system comprises an input device, preferably a joystick, wherein the input device is connected to the computing device in a signaling communication manner, and wherein the input device is configured to receive control commands from the pilot to provide the pilot's control commands to the computing device as control input.

[0098] Aspect 18 comprises an aircraft comprising the auxiliary system according to one of aspects 14 to 17, wherein the aircraft comprises a plurality of lift generating propulsion devices.

[0099] Aspect 19. An aircraft according to aspect 18, wherein each of the plurality of propulsion devices comprises a rotor and an electric motor for driving the corresponding rotor.

[0100] Aspect 20 An aircraft according to either Aspect 18 or 19, wherein the propulsion device is arranged such that the propulsion device generates vertical lift. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] According to the invention, the different and exemplary features described above can be combined with each other as long as this is technically convenient and appropriate. In particular, features disclosed in conjunction with a method can also be combined with device features, and vice versa. Further combinable features, advantages and embodiments of the invention are disclosed in the following description of examples of embodiments and with reference to the accompanying drawings. It shows:

[0102] Figure 1 shows a (super)ellipsoid for an aircraft in pseudo 3D representation in torque-thrust space;

[0103] Figure 2 An embodiment example of a dynamic representation of a control limit as may be generated using an embodiment example of a method for assisting a pilot and / or an embodiment example of an assistance system is shown;

[0104] Figure 3 Shows something like Figure 2 It is used to represent two different time points (periods);

[0105] Figure 4 schematically shows a 2D representation for illustrating an exemplary calculation of control limits; and

[0106] Figure 5 An embodiment of an aircraft is shown. DETAILED DESCRIPTION

[0107] As an example, Figure 1 An ellipsoid E for an aircraft is shown as described above in a pseudo 3D representation in torque-thrust space, with one dimension (in this case the yaw torque) being specified in a fixed manner. The ellipsoid E thus symbolizes the currently available control quantities in the remaining three spatial directions - thrust, pitch torque and roll torque.

[0108] The ellipsoid E describes the flight state vector γ( Figure 1 The instantaneous control limits of the ellipsoid E (not shown) are given by the vector γ, which - starting from the center point of the ellipsoid E - can only be located on its surface or in its interior. The vector γ represents the state of the aircraft at a specific point in time of flight in terms of its pitch, roll, yaw and total thrust, and the vector γ located within the boundaries or limits of the ellipsoid is expected for stable flight conditions. The control parameters located within the ellipsoid will indicate the amount of control that can be operated on the aircraft for achieving stable flight conditions. Outside the interior of the ellipsoid defines unstable and undesirable aircraft areas. The interior of the ellipsoid E indicates the physically achievable range of control over the aircraft, i.e., those flight conditions that the pilot can currently achieve with the aircraft.

[0109] Based on this mathematical-physical fact, it is now possible to obtain a visual representation of the present invention by technical means, preferably using the assistance system 1 and particularly preferably using the display device 29 (see Figure 5 ) - clearly and easily show the pilot the Figure 1 The resulting technical contribution improves the human-machine interaction between the pilot and the aircraft in such a way that the pilot is always aware of the physical performance limits of the aircraft to be controlled. This prevents the pilot from over-manipulating the aircraft, which could result in a crash.

[0110] Figure 2 1 shows how it is possible, for example, to use a method according to the invention (the method essentially comprising the method step of calculating a plurality of instantaneous control limits and the further method step of displaying the calculated control limits by means of a display device) and / or an assistance system 1 (having a calculation device and a display device, wherein the assistance system is preferably configured to implement the above method), in particular a display device 29 (see Figure 5 ) generates the corresponding representation.

[0111] In the process of the present invention and if configured accordingly, the flight state vector γ( Figure 2 The current control limits of the control amount for each component of the auxiliary system (not shown) are dynamically displayed to the pilot. For this purpose, the display 1 of the auxiliary system displays for each component, namely for the aircraft 20 about the roll axis x, the pitch axis y and the yaw axis z (see Figure 5 ), a fixed rectangular display area 2 is provided, only for the rolling moment is a rectangular display area 2 explicitly mentioned. The displays or display areas 2 for the individual components are arranged around a central display area 2a, in which further control-related displays (not shown) can be presented. Within the display area 2, the dynamically calculated control value limits for the relevant components are displayed in red (at 3 and 4), wherein one of these limits indicates a possible lower limit of the relevant component and the other limit indicates the associated upper limit. Reference symbol 5 shows an average value (mean of the lower limit 4 and the upper limit 3). The area 6 between limit 3 and limit 4 is colored green and represents the physically achievable control range of the aircraft (with respect to the component in question).

[0112] Reference symbol 8 denotes (particularly with respect to the upper control limit 3 and the lower control limit 4) an instantaneous control value indicating the current control value of the component of the relevant control limit 3, 4. The instantaneous control value 8 is white, but changes color when it approaches one of the control limits 3, 4 (limited instantaneous control value 9). Figure 2 The control about the pitch axis ("pitch") and the control about the yaw axis ("yaw") are shown symbolically. The instantaneous control value 8 about the pitch axis is still a long way from the control limits 3, 4. The instantaneous control value 9 about the limit of the yaw axis ("yaw") has already reached the left-hand control limit and is therefore shown in a different color.

[0113] In other words, the yaw moment has reached its maximum (or minimum) allowable value; further control input γ in this direction Cmd This is currently no longer possible. Therefore, the instantaneous control value 9 of the relevant limit is colored differently, preferably in red, and is located at or above the relevant control limit.

[0114] The thrust is almost at or near its maximum possible value. Therefore, the instantaneous control value of the thrust is positioned and also displayed differently. In particular, the frame of the instantaneous control value is slightly thicker and the coloring can also be chosen differently. For example, the instantaneous control value can be colored yellow.

[0115] The instantaneous control values ​​of roll and pitch are close to the neutral control value of 5 and are therefore colored white.

[0116] The control limits 3 and 4 as well as the area 6 within the control limits 3, 4 and the neutral control value 5 are dynamically movable within the (fixed) display field 2, depending on the current flight state or pilot control commands. The display within the display field 2 does not have to be symmetrical about the field border (rectangular outline), in particular for thrust.

[0117] Figure 2 The following special cases are also explicitly marked here:

[0118] The instantaneous control value 8 represents the currently commanded pitch torque (element of the 4×1 vector γ; not shown) on the aircraft fuselage or its display, which, like all other components, is provided at a preferably constant update rate, in particular by means of the above-mentioned calculation means (see Figure 5 ), for example, by means of the flight control laws implemented there. As already described, the commanded roll, yaw and thrust values ​​(also elements of the vector γ) are shown in the other three displays or display fields 2 .

[0119] At the limited instantaneous control value 9, none of the four commanded torque / thrust values ​​(elements of vector γ) can exceed the superellipse of the control quantity and therefore cannot exceed the dynamic limits (see also reference symbols 3, 4), as in Figure 2 2 is shown as an example for a yaw value.

[0120] The thick, preferably red bars or lines indicate the current control limits of the thrust according to reference symbol 10. These bars (corresponding to the limits 3, 4 mentioned above) are continuously moved according to the state of the aircraft and the pilot's input, thus increasing and decreasing the control amount on the corresponding axis. This also applies similarly to the display of roll, pitch and yaw.

[0121] This can also be Figure 3 In FIG. 1 , the thick bars of the upper control limit 3 and the lower control limit 4 are dynamically changed between period (time) k and the period (time) k+1 thereafter. It can be seen that, for example, due to large roll and pitch commands, the control amount (especially about the yaw axis) is changed at period k+1 (at Figure 3 is significantly smaller in period k (to the right) than in period k (to the left).

[0122] The available control amount is preferably displayed in green (see Figure 2 The corresponding area (see reference symbol 6 ) for the control about the roll axis of the aircraft changes its size dynamically depending on the position of the limit bars (control limits 3 , 4 ).

[0123] Figure 4 A 2D representation illustrating the calculation of the dynamic limit is shown, as mathematically detailed above.

[0124] Only the thrust (Y-axis) and the pitch moment (X-axis) are shown here as examples. The scalar values ​​N0 and T0 indicate the center of the superellipsoid located at the intersection of the two associated lines. max and T max The corresponding semi-axis lengths are described for the hyperellipsoid E. The same applies to the other axes (roll and pitch) not shown here.

[0125] Depending on the position of the vector γ, there are dynamic upper and lower control limits for the individual components of the vector γ, in Figure 4 Marked as and For each individual component these also depend on the values ​​of the other components, as already described.

[0126] For example, the instantaneous control limit of thrust and It is generated by running from γ parallel to the ordinate to the point of intersection with the ellipsoid E. The same applies to the pitch moment and its instantaneous control limit with respect to the abscissa (and corresponding other components or dimensions; Figure 4 not shown).

[0127] Figure 5 An embodiment of an aircraft 20 in the form of an eVTOL is schematically shown. The aircraft 20 has a plurality of propulsion devices 21. Each of the propulsion devices 21 comprises a propeller or rotor 22 with a fixed pitch and an electric motor 23 for driving the rotor 22. The rotors 22 are all arranged in a common horizontal plane 24 or are all arranged parallel to a common horizontal plane 24, wherein the rotor blades are inclined (fixed pitch angle) relative to the horizontal plane 24 or relative to a supporting structure.

[0128] An aircraft fuselage 25 including a cockpit is located below the horizontal plane 24. A pilot 26 flies or controls the aircraft 20 by using an input device 27 in the form of a joystick 27. The aircraft 20 also includes a computing device 28. The computing device 28 is connected to the input device 27 in a signal communication manner. Reference symbol 29 denotes a display device. Figure 5 In the embodiment example shown in , the display device is configured as a display (screen) 29. The display device 29 is in turn connected to the computing device 28 in a signal communication manner. The computing device 28, the input device 27 and the display device 29 together jointly form the auxiliary system 1.

[0129] If the pilot 26 now moves the control column 27 to control the aircraft 20 , the computing device 28 receives the corresponding control signals and can perform the calculations as part of the method described above. The dynamically calculated instantaneous control limits can then be shown to the pilot 26 via the display 29 .

[0130] Reference Symbols List

[0131] 1. Auxiliary systems

[0132] 2 / 2a Display area

[0133] 3 Upper control limit

[0134] 4 Lower control limits

[0135] 5 Neutral control value

[0136] 6 Areas within control limits

[0137] 7 -

[0138] 8 Instantaneous control value

[0139] 9 Limited instantaneous control value

[0140] 20 Airplane

[0141] 21 Propulsion

[0142] 22 Rotor

[0143] 23 Engine / Motor

[0144] 24 Horizontal plane

[0145] 25 Aircraft fuselage

[0146] 26 Pilot

[0147] 27 Input device / joystick

[0148] 28 Computing Devices

[0149] 29 Display device

[0150] E Ellipsoid

[0151] γ Vector

[0152] T Thrust

[0153] x The roll axis of the aircraft

[0154] y pitch axis of the aircraft

[0155] z The yaw axis of the aircraft

Claims

1. A method for assisting a pilot (26) in controlling an aircraft (20) having a plurality of lift-generating propulsion devices (21), the method comprising the following method steps: (a) For each of the following, calculate the instantaneous control limits (3, 4): (a1) control of the aircraft about its roll axis (x), (a2) control of the aircraft about its pitch axis (y), (a3) control of the aircraft about its yaw axis (z), and (a4) control of the total thrust (T) of all propulsion devices (21); and (b) displaying the calculated control limits (3, 4) to the pilot (26) via a display device (29).

2. A method according to claim 1, wherein the calculation of the control limits (3, 4) is performed based on the instantaneous flight state of the aircraft (20) and / or the instantaneous control of the aircraft (20), preferably based on the control of the aircraft about its roll axis (x), the control of the aircraft about its pitch axis (y), the control of the aircraft about its yaw axis (z) and the control of the total thrust (T) of all propulsion devices (21).

3. Method according to one of the preceding claims, wherein the calculation of the control limits (3, 4) is performed dynamically, preferably periodically.

4. Method according to one of the preceding claims, wherein at least one of the control limits (3, 4) is indicated relative to a neutral control value (5).

5. The method according to one of the preceding claims, wherein at least one of the control limits (3, 4), preferably all of the control limits (3, 4), has an upper control limit (3) and a lower control limit (4).

6. A method according to claim 5, wherein for at least one control limit (3, 4), preferably for all control limits (3, 4), the upper control limit (3) and / or the lower control limit (4) is highlighted in a graphical manner, preferably by a signal color.

7. A method according to one of the preceding claims, wherein instantaneous control values ​​(8) are displayed for controlling the aircraft about its roll axis (x), for controlling the aircraft about its pitch axis (y), for controlling the aircraft about its yaw axis (z) and / or for controlling the total thrust (T) of all propulsion devices (21).

8. A method according to one of the preceding claims, wherein the control of the aircraft is described by a vector (γ) comprising four components, namely three components of a torque (τ) about the respective aircraft axes (x, y, z) and the total thrust (T), wherein the three components of the torque (τ) depend on the arrangement and the instantaneous thrust of the individual propulsion devices (21), and the instantaneous limits of the vector γ with respect to each of the four components are determined to calculate the control limits (3, 4).

9. An assistance system (1) for assisting a pilot (26) in controlling an aircraft (20), the assistance system (1) comprising: (a) Calculation means (28) for calculating the instantaneous control limits (3, 4) for each of: (a1) control of the aircraft about its roll axis (x), (a2) control of the aircraft about its pitch axis (y), (a3) control of the aircraft about its yaw axis (z), and (a4) control of the total thrust (T) of all propulsion devices (21), and (b) Display means (29) for displaying the calculated control limits (3, 4) to the pilot (26).

10. An aircraft (20) having an auxiliary system (1) according to claim 9, wherein the aircraft (20) comprises a plurality of lift-generating propulsion devices (21).

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