3 ms·
Why can't we just dump massive currents into spring returning solenoids with ~5mm or ~1/4" range of motion, and amplify that motion through tendon systems for w
by numpad0 7mo ago
Why can't we just dump massive currents into spring returning solenoids with ~5mm or ~1/4" range of motion, and amplify that motion through tendon systems for whole joint motion ranges?
- moffkalast 7mo agoCause it'll run three minutes on battery power.
- numpad0 7mo agoJust put a chainsaw power pack in the back. That'll be massively cool anyway.
- cyberax 7mo agoYou can play around with a solenoid calculator like this one: https://www.getzenquery.com/tools/solenoid-force-calculator/ https://www.getzenquery.com/tools/solenoid-force-calculator/ TLDR; is that you need high current, meaning a lot of ohmic heating. With non-negligible back-EMF resulting in even more losses. Rotating motors essentially "lengthen" the travel of the "plunger" compared to linear motors.
- tlb 7mo agoHeat goes up with the square of current, so putting 10x the current to get 10x the force means 100x the heat. Still, I think this idea is under-explored. There are probably applications for robots that move really fast, but only for a second before having to cool down.
- sokka_h2otribe 7mo agoAnother way to look at it, is that bldc motors are sort of like solenoids with the motion between between poles of the motor. There's a limit in both cases to what you can do and how much flux you can push
- jimbooonooo 7mo agoThere is no free lunch: using mechanical amplification results in the same problem as described above, and spring return means that your actuator has to push that much harder to overcome the spring. Net is that a couple of figures of merit limit the performance of electromagnetic systems, and being sneaky won't let you exceed them.