Propeller impact detection and force reduction

Abstract

In various embodiments, a motor controller includes a rotor strike detector and a drive and control unit. The motor controller generates a plurality of phase-shifted sinusoidal signals. The rotor strike detector detects a rotor strike including by comparing a commanded control signal and an adaptive control signal. The adaptive control signal is associated with controlling the rotor and includes the phase-shifted sinusoidal signals. A rotor strike is detected based on a change in a plurality of sinusoidal signals. The drive and control unit, in response to detecting that the aircraft is above a threshold altitude and detecting the rotor strike, sets a value of the adaptive control signal to keep the aircraft airborne, and reduces a striking force applied to an object being struck by the rotor including by prioritizing the keeping the aircraft airborne over the reducing the striking force applied to the object being struck by the rotor.