Sensorless Field Oriented Control of BLDC Motors for MAVs

To achieve longer flight duration of the microaerial vehicles (MAVs) it is needed to optimize theirpropulsion system. A typical propulsion system of VTOL(vertical take-off and landing) MAV consist of the propellerBLDC (brushless DC) motor, motor controller and battery(typically Lithium based chemistry). All these parts of thepropulsion system can be optimized in a specific way. In thecase of the propeller, this can be done by the optimization ofstatic and dynamic thrust performance. The motorconstruction can be optimized by using lighter materials orstronger rotor magnets. As for the battery - alternativepower sources like solar panels, hydrogen fuel cells etc. maybe used. We are focusing on the optimization of the motorcontrol part. In this paper, we are presenting synthesis ofthe BLDC controller using the field oriented controlstrategy which promises better performance in thedynamical response of the propulsion system, lower powerconsumption and generally higher efficiency in comparisonwith the traditional six step commutation techniques

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements