L'Italia in una immagine
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L'Italia in una immagine.
Avevo scattato la foto diversi anni fa, in un ospedale. Invece di cambiare la serratura guasta un "genio" pensò bene di fare due fori alle ante della porta per metterci catena e catenaccio.
Ci avrei incatenato il responsabile di reparto, a quella porta, con un cartello al collo: sputatemi.
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Gli ultimi otto messaggi ricevuti dalla Federazione
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@mayintoronto @mcc I just got this
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@tshirtman ha!
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But, also have to hand it to my neighbors in this case. This neighborhood is terrible about animal welfare, but when a person is obviously in trouble, several folks showed up to see what was going on and try to help.
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@schwegler this is true, though. Never been happier than when I could walk to two Asian markets, a Mediterranean market, a library, and a dozen restaurants. The large grocery store was a little further away, but an easy bike ride.
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Man, religion really does a number on people. Just met a guy calling himself Man of God who's trying to not eat or drink anything for a week, while walking all day in Texas heat. He was laying on the sidewalk face down. Wouldn't take water. A neighbor called 911, EMTs came, not sure if he left with them or if he walked on. He's no longer on the sidewalk, anyway. I don't know what kind of safety net helps folks like that but we definitely don't have enough of one.
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High Performance Motor Control With FOC From the Ground Up
Testing the FOC-based motor controller. (Credit: Excessive Overkill, YouTube)
Vector Control, also known as Field Oriented Control or FOC is an AC motor control scheme that enables fine-grained control over a connected motor, through the precise control of its phases. In a recent video [Excessive Overkill] goes through the basics and then the finer details of how FOC works, as well as how to implement it. These controllers generally uses a proportional integral (PI) loop, capable of measuring and integrating the position of the connected motor, thus allowing for precise adjustments of the applied vector.If this controller looks familiar, it is because we featured it previously in the context of reviving old industrial robotic arms. Whether you are driving the big motors on an industrial robot, or a much smaller permanent magnet AC (PMAC) motor, FOV is very likely the control mechanism that you want to use for the best results. Of note is that most BLDC motors are actually also PMACs with ESC to provide a DC interface.
The actual driving is done with two MOSFETs per phase, forming a half-bridge, switching between the two rails to create the requisite PWM signal for each phase. Picking the right type of MOSFET was somewhat hard, especially due to the high switching currents and the high frequency at 25 kHz. The latter was picked to prevent audible noise while driving a robot. Ultimately SiC MOSFETs were picked, specially the GeneSiC G3R30MT12K. Of note here are the four legs, with a fourth Kelvin Source pin added. This is to deal with potential gate drive issues that are explained in the video.
With the hardware in place, whether following the [Excessive Overkill] GitHub projects or not, what makes all of it work is the software. This is where the microcontroller aspect is essential, as it has to do all the heavy lifting of calculating the new optimal vector and thus the current levels per phase. In this controller an STM32F413 is used, which generates the PWM signals to drive the half-bridges, while reading the measurements from the motors with its ADC.
As can be seen in the resulting use of this controller with old industrial robots, the FOC controller works quite well, with quiet and smooth operation. This performance is why we’re likely to see FOC and PMAC motors used in applications like 3D printers in the future, though the rule of ‘good enough’ makes the cost of an FOC controller still a tough upsell over a simple open loop stepper-based system.
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@Natasha_Jay
rortfl!
