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.
Altair has released an update of its HyperWorks computer-aided engineering simulation suite that includes new features focusing on four key areas of product design: performance optimization, lightweight design, lead-time reduction, and new technologies.
At IMTS last week, Stratasys introduced two new multi-materials PolyJet 3D printers, plus a new UV-resistant material for its FDM production 3D printers. They can be used in making jigs and fixtures, as well as prototypes and small runs of production parts.
In a line of ultra-futuristic projects, DARPA is developing a brain microchip that will help heal the bodies and minds of soldiers. A final product is far off, but preliminary chips are already being tested.
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