Aircraft and method for flight control of an aircraft during flight

Patent metadata

Field	Value
Publication number	US-12468312-B2
Application number	US-202418421286-A
Country	US
Kind code	B2
Filing date	Jan 24, 2024
Priority date	Mar 14, 2023
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

Abstract

A method for flight control of an aircraft with multiple actuators during flight is disclosed. For each actuator, a control command is computed according to at least one predetermined control law and based on pilot inputs and sensor measurements in relation to a physical state of the aircraft. The respective control commands are provided to the actuators. The control commands are independently monitored by estimating or measuring a current physical state of the aircraft and comparing it with the control commands. This comparison includes checking whether the control commands stabilize the aircraft in a stable state in the absence of both disturbances and pilot inputs according to at least one predefined criterion. If the monitoring indicates a lack of stability, transmission of the control commands is prevented and a backup control command is computed for each actuator.

First claim

What is claimed is:

1 . A method for flight control of an aircraft during flight, the aircraft including a plurality of N,N∈N actuators for operating movable flight surfaces or propulsion units of the aircraft via pilot inputs (w), the method comprising:
computing, for each actuator, a control command (u,u∈RN) established according to at least one predetermined control law (K) for control of a movable flight surface or a propulsion unit operated by a respective actuator and based on the pilot inputs (w) and sensor measurements in relation to a physical state (x) of the aircraft and providing respective control commands (u) to the actuators;
independently monitoring the control commands (u) by estimating or measuring a current physical state (x) of the aircraft and comparing the current physical state (x) to the control commands (u), the comparing including checking whether the control commands (u) stabilize the aircraft in a stable state x for time t→∞ in an absence of both disturbances (d) and pilot inputs (w) according to at least one predefined criterion; and
in response to the monitoring indicating a lack of stability, preventing transmission of the control commands (u) to the actuators and independently computing, for each actuator, a backup control command (udissimilar) established according to at least one predetermined backup control law (Kdissimilar) for control of the flight surface or the propulsion unit operated by a given actuator and providing respective backup control commands (udissimilar) to the actuators,
wherein the control commands (u) are calculated based on a relation: u=w−K(x), according to which the pilot inputs (w) are augmented with a control law (K(x)), the control law (K(x)) being non-linear and devised to asymptotically stabilize undisturbed error dynamics in absence of pilot inputs: t→∞:x→x0 for d=w=0, wherein x0 denotes an equilibrium condition.

2 . The method of claim 1 , wherein:
the at least one predefined criterion is met if:

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x′=f(x, u,d) denotes a temporal evolution or time derivative (x′) of the physical state (x) of the aircraft expressed as a mathematical function (f) dependent on the physical state (x) of the aircraft, the state (x) being defined by one or more of attitude angles, angular rates, position, or translational velocity, the mathematical function (f) being further dependent on the control commands (u) and further dependent on unknown disturbances (d), the disturbances including one or more of atmospheric disturbances, a system degradation, a mass distribution differing from a nominal configuration, or other disturbances that affect a motion of the aircraft; and
V=xT·P·x denotes a quadratic Lyapunov function with P=PT>0, so that the relation: V>0:x>0 holds and e denotes a numerical parameter >0.

3 . The method of claim 2 , wherein the parameter e is used as a criterion to pause the monitoring if the physical state (x) is close to an equilibrium condition x=0, i.e., for x≤ϵ.

4 . The method of claim 2 , wherein for x≤ϵ comparison is paused and the respective control commands (u,u∈RN) are provided to the actuators.

5 . The method of claim 4 , wherein the method further comprises, in response to a disturbance (d≠0) or pilot input (w=0), causing an excitement of the aircraft such that x>ϵ and the monitoring resumes.

6 . The method of claim 1 , wherein:
the at least one predefined criterion is met if:

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Assignees

• Volocopter Gmbh

Inventors

• Stephan Johannes

Classifications

• B64C13/18

  using automatic pilot · CPC title

• G05D2109/254

  Flying platforms, e.g. multicopters · CPC title

• G05D1/87

  using redundant control arrangements · CPC title

• G05D1/495 Primary

  to ensure stability · CPC title

• G05D2105/22

  of humans · CPC title