Propeller impact detection and force reduction

Patent metadata

Field	Value
Publication number	US-10507908-B2
Application number	US-201916249645-A
Country	US
Kind code	B2
Filing date	Jan 16, 2019
Priority date	Dec 7, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A commanded control signal is compared against an adaptive control signal in order to detect a rotor strike by a rotor included in an aircraft, wherein the adaptive control signal is associated with controlling the rotor and the adaptive control signal varies based at least in part on the commanded control signal and state information associated with the rotor. In response to detecting the rotor strike, a control signal to the rotor is adjusted in order to reduce a striking force associated with the rotor.

First claim

What is claimed is:

1. A system, comprising:
a processor; and
a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to:
detect a rotor strike of an object striking an aircraft rotor, the detection including comparing a commanded control signal against an adaptive control signal including by:
determining a degree to which the adaptive control signal deviates from a reference signal;
comparing the degree of deviation against a detection threshold; and
in response to the degree exceeding the detection threshold, declaring that the rotor strike has been detected,
wherein the adaptive control signal is associated with controlling the rotor and the adaptive control signal varies based at least in part on the commanded control signal and state information associated with the rotor; and
in response to detecting the rotor strike, adjust a control signal to the rotor to reduce a striking force applied to the object being struck by the rotor and mitigate damage to at least one of the object being struck and the rotor.

2. The system recited in claim 1 , wherein the instructions for comparing the commanded is control signal against the adaptive control signal in order to detect the rotor strike include instructions for determining a reference signal based at least in part on the commanded control signal and the adaptive control signal includes a sinusoidal signal.

3. The system recited in claim 1 , wherein the instructions for comparing the commanded control signal against the adaptive control signal in order to detect the rotor strike include instructions for determining a reference signal based at least in part on the commanded control signal, wherein the reference signal includes a measurement threshold.

4. The system recited in claim 1 , wherein the instructions for comparing the commanded control signal against the adaptive control signal in order to detect the rotor strike include instructions for determining a reference signal based at least in part on the commanded control signal, wherein the reference signal includes a sinusoidal reference signal.

5. The system recited in claim 1 , wherein the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, using an electrical connector to electrically disconnect the adaptive control signal from a rotor input signal; and
in response to electrically disconnecting the adaptive control signal from the rotor input signal, using a pull resistor to set the rotor input signal to a known value associated with reducing the striking force associated with the rotor.

6. The system recited in claim 1 , wherein the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, opening a power switch in a switched converter, wherein the power switch is connected to a power supply at one end and the adaptive control signal at the other end such that opening the power switch electrically disconnects the adaptive control signal from the power supply; and
in response to detecting the rotor strike, closing a ground switch in the switched converter, wherein the ground switch is connected to ground at one end and the adaptive control signal at the other end such that closing the power switch electrically connects the adaptive control signal to ground.

7. The system recited in claim 1 , wherein the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, opening a power switch in a switched converter, wherein the power switch is connected to a power supply at one end and the adaptive control signal at the other end such that opening the power switch electrically disconnects the adaptive control signal from the power supply; and
in response to detecting the rotor strike, opening a ground switch in the switched converter, wherein the ground switch is connected to ground at one end and the adaptive control signal at the other end such that opening the power switch electrically disconnects the adaptive control signal from ground.

8. The system recited in claim 1 , wherein the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, obtaining an altitude associated with the aircraft;
comparing the altitude against an altitude threshold;
in response to the altitude exceeding the altitude threshold, at least temporarily adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor; and
in response to the altitude not exceeding the altitude threshold, adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor, at least until one or more of the following occurs: a reset or a part replacement.

9. The system recited in claim 1 , wherein the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, obtaining an altitude associated with the aircraft;
comparing the altitude against an altitude threshold;
in response to the altitude exceeding the altitude threshold, at least temporarily adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor, wherein the rotor is permitted to restart in response to a pilot restart instruction without a reset prior to the pilot restart instruction or a part replacement prior to the pilot restart instruction; and
in response to the altitude not exceeding the altitude threshold, adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor, at least until one or more of the following occurs: a reset or a part replacement.

10. The system recited in claim 1 , wherein:
the aircraft includes a parachute system; and
the instructions for adjusting the control signal to the rotor in order to reduce the striking force include instructions for:
in response to detecting the rotor strike, obtaining an altitude associated with the aircraft;
comparing the altitude against a higher altitude threshold and a lower altitude threshold;
in response to the altitude not exceeding the lower altitude threshold, adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor; and
in response to the altitude exceeding the higher altitude threshold, adjusting the control signal to the rotor in order to reduce the striking force associated with the rotor, wherein in response to the altitude exceeding the lower altitude threshold and not exceeding the higher altitude threshold, the striking force associated with the rotor is not reduced.

11. A method, comprising:
detecting a rotor strike of an object striking an aircraft rotor, the detection including comparing a commanded control signal against an adaptive control signal including by: determining a degree to which the adaptive control signal deviates from a reference signal; comparing the degree of deviation against a detection threshold; and in response to the degree exceeding the detection threshold, declaring that the rotor strike has been detected, wherein the adaptive control signal is associated with controlling the rotor and the adaptive control signal varies based at least in part on the commanded control signal and state information associated with the r

Assignees

• Kitty Hawk Corp

Inventors

• Saunders Christopher Scott

Classifications

• B64U2201/00

  UAVs characterised by their flight controls · CPC title

• B64D45/00

  Aircraft indicators or protectors not otherwise provided for · CPC title

• B64C27/006 Primary

  Safety devices · CPC title

• B64D31/10

  for preventing asymmetric thrust · CPC title

• B64D17/80

  in association with aircraft, e.g. for braking thereof · CPC title