Signal Processing

I came up with the idea of expanding the “PID vs ML” article series to seriously investigate what are the real-world possibilities of augmenting classical PID controllers with self-diagnostics capabilities using FFT (unbalanced motor torque, gearbox damage, bearing faults, etc.). Of course my nature immediately kicked in. Instead of just slapping FFT onto the PID routines, calling it a day and ticking the ‘done’ box like a normal person, I did what I always do - tore the whole thing apart into pieces and started cursing stupid imperfection of the real computer world (as opposed to that beautiful, clean mathematical fantasy we all pretend exists). We’re talking about a finite number of samples, precision butchered by IEEE 754 float/double quirks, rounding errors that sneak in like uninvited guests, and … You think I’m nitpicking again…? Yeah, probably. My nature. But hold my coffee - I’ve got a perfect real-world example coming right up that shows why sometimes being this pedantic actually saves your ass. ...

To kick off our adventure with analog computing systems, let’s start with a bit of history. It all began in 1947 when John Bardeen and Walter Brattain built the first working transistor prototype using germanium at Bell Labs. Sidenote: in reality, many labs around the world were working on the concept, so it’s a collective achievement. The jump from bulky vacuum tubes to tiny transistors was a game-changer - it triggered explosive growth in electronics. The next big milestone came quickly: in 1967 Karl D. Swartzel developed the first operational amplifier - an electronic building block that could perform mathematical operations: ...

Recently, I have been developing a PID controller class for my Qt projects. During implementation, I encountered a very interesting problem from the field of signal theory that I believe is worth sharing. A classic PID controller works in fixed time steps dt. At each step it compares the current process value with the setpoint, considers the previous value and computes the output. And right here the first serious problem shows up - the inertia inherent in real-world measurement system. ...