US 12,397,908 B1Granted

Sensorless propeller damage detection systems and methods

AssigneeAmazon Technologies, Inc.

InventorsXiaoqi Wang, Lizon Maharjan, Tausif Husain, Sheverria Antony Aikens, Frederic Pierre Lacaux

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Abstract

Sensorless propeller damage detection systems and methods may receive and process motor quadrature-axis currents to extract current ripples and fast average current values. In addition, the current ripples and fast average current values may be further processed to generated normalized rms (root-mean-square) values of the current ripples. Further, the calculated values may be compared to one or more threshold values over a time duration to determine whether a propeller is damaged. In this manner, the sensorless propeller damage detection systems and methods may quickly, reliably, and accurately detect propeller damage without any additional sensors or dedicated hardware and with low computational cost, while also minimizing false positive determinations of propeller damage.

Claims20

Dependent claims

A method to detect damage to a propeller of an aerial vehicle, comprising:

receiving, by a control system, a motor quadrature-axis current associated with a motor and corresponding propeller of an aerial vehicle;
removing, by the control system, high frequency noise from the motor quadrature-axis current;
extracting, by the control system, current ripples from the motor quadrature-axis current;
determining, by the control system, rms (root-mean-square) values associated with the current ripples;
extracting, by the control system, fast average current values from the motor quadrature-axis current;
applying, by the control system, lower and upper limits to the fast average current values to generate average current values;
calculating, by the control system, normalized rms values based on the rms values associated with the current ripples and the average current values;
determining, by the control system, that a first condition is satisfied in response to the normalized rms values being greater than a threshold rms value;
determining, by the control system, that a second condition is satisfied in response to the fast average current values being greater than a threshold average current value;
determining, by the control system, that the propeller is damaged in response to the first and second conditions being satisfied for a time duration that is greater than a threshold time value;
and
instructing, by the control system, operation of the aerial vehicle based at least in part on the determination that the propeller is damaged.

9 more elements

An aerial vehicle, comprising:

a fuselage;
a motor arm coupled to the fuselage;
a motor coupled to the motor arm;
a propeller coupled to and rotated by the motor, at least a portion of the motor arm extending within a volume of thrust generation associated with the motor and propeller;
and
a control system configured to at least:
extract current ripples from a motor quadrature-axis current associated with the motor;
extract fast average current values from the motor quadrature-axis current;
calculate normalized rms values based on the current ripples and the fast average current values;
determine that the propeller is damaged in response to a first condition related to the normalized rms values and a second condition related to the fast average current values being satisfied over a time duration that is greater than a threshold time value;
and
instruct operation of the aerial vehicle based at least in part on the determination that the propeller is damaged.

9 more elements

Dependencies are inferred from the claim text.