Abstract: Embodiments described herein provide active dampening of flexible modes of a UAV during flight operations. During operation of a UAV having a flexible airframe, the thrust and/or torque of the motor(s) coupled to propellers can induce flexing in the airframe that reduces the flight performance of the UAV. Measurements of a linear acceleration and/or an angular rate at a location proximate to the motor are performed, and flexible modes in the airframe of the UAV are identified based on the measurements. An operation of the motor(s) is modified based on the measurements to dampen the flexible mode.

Abstract: Embodiments described herein provide active dampening of flexible modes of a UAV during flight operations. During operation of a UAV having a flexible airframe, the thrust and/or torque of the motor(s) coupled to propellers can induce flexing in the airframe that reduces the flight performance of the UAV. Measurements of a linear acceleration and/or an angular rate at a location proximate to the motor are performed, and flexible modes in the airframe of the UAV are identified based on the measurements. An operation of the motor(s) is modified based on the measurements to dampen the flexible mode.

Abstract: A method and apparatus for controlling regeneration for a motor. An instantaneous voltage provided by a power supply to the motor is identified using a voltage signal received from a voltage sensor. A new average voltage is computed for the motor using the instantaneous voltage, a previously computed average voltage, and a weight factor for the instantaneous voltage. A difference between the new average voltage and the instantaneous voltage is compared to a selected threshold to determine whether a regeneration condition exists. Operation of the motor is controlled such that a duty cycle of the motor does not decrease in response to a determination that the regeneration condition exists.

Abstract: A method and apparatus for controlling commutation of a motor. A voltage is measured at each of a plurality of windings of a motor using an electric circuit. A controller computes an overall back electromotive force for the motor using the voltage measured at each winding in the plurality of windings. The controller generates a result having either a first value or a second value based on the overall back electromotive force. The controller adjusts the commutation phase and the commutation period of the motor using the result.

Abstract: A system and method of evacuating a downed tactical operator from a hostile environment comprising adding an evacuation belt strap to a PALS grid on a body armor vest by using belt keepers. The evacuation belt strap is made by forming loops at the ends of the strap to function as handles to be grasped by rescuers of the downed operator.

Abstract: A method and apparatus for controlling regeneration for a motor. An instantaneous voltage provided by a power supply to the motor is identified using a voltage signal received from a voltage sensor. A new average voltage is computed for the motor using the instantaneous voltage, a previously computed average voltage, and a weight factor for the instantaneous voltage. A difference between the new average voltage and the instantaneous voltage is compared to a selected threshold to determine whether a regeneration condition exists. Operation of the motor is controlled such that a duty cycle of the motor does not decrease in response to a determination that the regeneration condition exists.

Abstract: A method and apparatus for controlling commutation of a motor. A voltage is measured at each of a plurality of windings of a motor using an electric circuit. A controller computes an overall back electromotive force for the motor using the voltage measured at each winding in the plurality of windings. The controller generates a result having either a first value or a second value based on the overall back electromotive force. The controller adjusts the commutation phase and the commutation period of the motor using the result.

Abstract: A method and apparatus for controlling a brushless direct current motor. An H-bridge is configured to couple a direct current power source to windings of the brushless direct current motor. The H-bridge comprises a plurality of switches. A motor controller is configured to close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings of the motor are short circuited. A desired direction for a current impulse to the windings is identified. The one of the plurality of switches is opened in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings. Another of the plurality of switches is closed in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings.

Abstract: A system and method of evacuating a downed tactical operator from a hostile environment comprising adding an evacuation belt strap to a PALS grid on a body armor vest by using belt keepers. The evacuation belt strap is made by forming loops at the ends of the strap to function as handles to be grasped by rescuers of the downed operator.

Abstract: A system and method of evacuating a downed tactical operator from a hostile environment comprising adding an evacuation belt strap to a PALS grid on a body armor vest by using belt keepers. The evacuation belt strap is made by forming loops at the ends of the strap to function as handles to be grasped by rescuers of the downed operator.

Abstract: A system and method of evacuating a downed tactical operator from a hostile environment comprising adding an evacuation belt strap to a PALS grid on a body armor vest by using belt keepers. The evacuation belt strap is made by forming loops at the ends of the strap to function as handles to be grasped by rescuers of the downed operator.

Abstract: A method and apparatus for controlling a brushless direct current motor. An H-bridge is configured to couple a direct current power source to windings of the brushless direct current motor. The H-bridge comprises a plurality of switches. A motor controller is configured to close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings of the motor are short circuited. A desired direction for a current impulse to the windings is identified. The one of the plurality of switches is opened in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings. Another of the plurality of switches is closed in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings.

Abstract: Methyltin compounds useful as catalysts in high-temperature esterification and polyesterification reactions are described. The esters and polyesters produced by the process possess superior physical/chemical properties such as improved color and thermal stability with less production of undesirable by-products. The greater stability of these catalysts allows their use in multistage polyesterification reactions and leads to lower use levels in some cases.