PID Control Challenges • Hacker News Board

Re: PID Control Challenges

#121

Post by NooneAtAll3 » Wed, Sep 27, 2023, 3:21 AM UTC

v9v wrote: post #56

NooneAtAll3 wrote: post #36

Earlier quoted context omitted.

best solutions will be "Insane value to instantly teleport to the point. Insane anti-value to instantly stop."

I think what you are suggesting is similar to the "dead-beat controller" in discrete-time control literature. While a controller designed with this method can get the position error measured at the sampling times to zero very quickly, it gives no guarantees that the error stays zero between the samples. This means the block could be wildly oscillating around the arrow in reality, but oscillating in such a way that it…

what I'm suggesting is "abuse of total reproducibility of the system" or "premonition"

nothing about real-life controllers

Re: PID Control Challenges

#122

Post by nullc » Wed, Sep 27, 2023, 5:52 AM UTC

kavouras wrote: post #109

nullc wrote: post #41

Earlier quoted context omitted.

it's pretty trivial! erghea -400 oybpx.k-40 oybpx.qk; (not that rot13 really obscures anything here!) The rest of the puzzles get pretty interesting, I shouldn't have just stopped on the first and spent all the time optimizing it. If the author sees this thread it would be fun if you could disturb the dynamics with the mouse after completing one. I wanna watch the ball catching piston right the ball if I poke it.

I just spent too much time messing around with this, so here's the results. The simulation has a limit on the maximum magnitude of the force of your controller, which in this example is 50. The system is described by x'' = -1.00204*x + u (by experimenting with console.log). The theoretical solution to minimize time to the origin on a system like this is a bang-bang strategy: go full actuation and at some point slam t…

Indeed, the optimal trajectory is to accelerate as hard as possible then decelerate as hard as possible so you land at 0 with dx=0.

It's more exciting to calculate the dynamics if you need to be jerk limited.

Re: PID Control Challenges

#123

Post by raducu » Wed, Sep 27, 2023, 6:36 AM UTC

yetihehe wrote: post #108

raducu wrote: post #104

Earlier quoted context omitted.

When does a syringe become a piston?

When you remove outer wall?

my bad, the piston is indeed just the inner moving part, my point was that we think of syringe as easy because it is not under pressure, but if you think in terms of car piston/cylinder you appreciate more why this can't work in a rocket fuel tank.