Abstract: Systems and methods for sensorless motor control may include a back EMF (electromotive force) observer, an adaptive EMF filter, magnitude compensation, hybrid rotor position and speed determination, rotor position and speed blending, and angle compensation. In order to provide accurate and reliable rotor position and speed estimations for a motor over a wide and varied range of speeds, at low speeds, during speed reversals, and/or in the presence of external forces, loads, or torques, the sensorless motor control may utilize a hybrid rotor position and speed determination that leverages both angle-based and magnitude-based methods. Further, the outputs of the two methods may be blended based on a shaping function to generate a final estimated rotor position and speed. Then, the motor may be more accurately and reliably controlled based on the final estimated rotor position and speed.

Abstract: This disclosure describes example reconfigurable propulsion mechanisms, example multi-rotor aerial vehicle apparatuses, and methods that may be used to alter the yaw torque polarity produced by one or more propulsion mechanisms in response to a detected loss of thrust produced by another propulsion mechanism of the aerial vehicle. For example, each reconfigurable propulsion mechanism may be configured to move between a normal operating position and a reconfigured operating position. When a reconfigurable propulsion mechanism is in a normal operating position, the yaw torque has a first polarity, such as clockwise. In comparison, when the same reconfigurable propulsion mechanism is in the reconfigured operating position, the yaw torque polarity produced by the propulsion mechanism is reversed and has a second polarity, such as counter-clockwise.

Abstract: Described is a sensor-less motor reversal (“SLMR”) apparatus that aids the reversal of motor rotation of a bidirectional motor, such as a brushless DC motor of an aerial vehicle. The SLMR includes an RPM dependent clutch that is rotated by a drive shaft of the motor and that engages an engageable shaft of the SLMR apparatus during a low RPM range of the motor during which indirect measurement of the RPM of the motor through a back-EMF of the motor is unreliable. As the engageable shaft increases in RPM, energy is stored by an energy storage mechanism of the SLMR. As the RPM of the motor decreases as part of a motor reversal, the energy stored by the energy storage mechanism is discharged and aids in the transition of the reversal of the motor from positive to negative, or negative to positive. As described, the SLMR apparatus is stateless.

Abstract: Described is a sensor-less motor reversal (“SLMR”) apparatus that aids the reversal of motor rotation of a bidirectional motor, such as a brushless DC motor of an aerial vehicle. The SLMR includes an RPM dependent clutch that is rotated by a drive shaft of the motor and that engages an engageable shaft of the SLMR apparatus during a low RPM range of the motor during which indirect measurement of the RPM of the motor through a back-EMF of the motor is unreliable. As the engageable shaft increases in RPM, energy is stored by an energy storage mechanism of the SLMR. As the RPM of the motor decreases as part of a motor reversal, the energy stored by the energy storage mechanism is discharged and aids in the transition of the reversal of the motor from positive to negative, or negative to positive. As described, the SLMR apparatus is stateless.

Abstract: Systems and methods to control aerial vehicles in degraded operational states are described. For example, for an aerial vehicle having six propulsion mechanisms arranged around a fuselage, one or more modified control schemes may be implemented to maintain control and navigation of the aerial vehicle responsive to a motor out situation, such as a failure of one propulsion mechanism. The modified control schemes may seek to emulate normal operation of a quadcopter, and/or may seek to utilize all remaining propulsion mechanisms to maintain controllability of the aerial vehicle in all six degrees of freedom of movement.

Abstract: Systems and methods to control aerial vehicles in degraded operational states are described. For example, for an aerial vehicle having six propulsion mechanisms arranged around a fuselage, one or more modified control schemes may be implemented to maintain control and navigation of the aerial vehicle responsive to a motor out situation, such as a failure of one propulsion mechanism. The modified control schemes may seek to emulate normal operation of a quadcopter, and/or may seek to utilize all remaining propulsion mechanisms to maintain controllability of the aerial vehicle in all six degrees of freedom of movement.