In the old days, it was common to excite the sin and cos windings with sinusoidal signals that were 90 degrees out of phase (sin and cos). Then when the shaft rotates, the rotor winding produces a fixed amplitude sine wave, whose phase shifts in proportion to the shaft angle. The control system must then resolve the phase angle of the rotor winding against a reference wave. This was a relatively easy thing to do with analog circuitry. The reference waveform could be the position command signal. The command signal to the actuator is then proportional to the phase error between the resolver rotor and the reference signal.
A middle school team from Rochester, Mich., has again nabbed the grand prize in the annual international Future City Competition, which drew students from 37 regions of the United States, as well as from England and China.
The word “smart” is becoming the dumbest word around. It has been applied to almost every device and system in our homes. In addition to smartphones and smart meters, we now hear about smart clothing and smart shoes, smart lights, smart homes, smart buildings, and every trendy city today has its smart city project. Just because it has a computer inside and is connected to the Web, does not mean it is smart.
Are you being paid enough? Do you want a better job? According to a recent survey Manpower released just before Engineers Week, employers and engineers don't see eye-to-eye about the state of US engineers' skills and experience.
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