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Can Repelling Magnets Replace the Spring in a Pogo Stick?

kjmagnetics.com

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Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#41

Post by jgibson »

darkerside wrote: post #35
weberc2 wrote: post #28

Earlier quoted context omitted.

Pretty much every critical system in a vanilla Toyota is already software-controlled, not to mention the legion of critical systems involved in air travel, elevators, medical equipment (e.g., pacemakers), etc. Not sure that this should bring comfort, but at least you need not be particularly frightened by your Tesla. :)

Aren't brakes and steering mostly manual? I don't think it's the right advice to tell people to trust Autopilot when it's failed in several egregious ways.

They are manual in the sense that there is a physical connection: the steering wheel is usually mechanically coupled with the steering rack, brakes usually through through hydraulics.

That said there are probably 5-20 systems in a car that can completely control these systems without any human input. Think of automatic emergency braking, traction control, vehicle stability control for the brakes, and autopark + powered steering for the steering.

Most of these systems have multiple redundancy and isolated monitors (eg, if autopark is on and the vehicle speed is > 10mph, the monitor will intervene) but there are still probably some theoretical situations where this could occur

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#43

Post by jgibson »

TylerE wrote: post #40
darkerside wrote: post #35

Earlier quoted context omitted.

Aren't brakes and steering mostly manual? I don't think it's the right advice to tell people to trust Autopilot when it's failed in several egregious ways.

Steering is electronic.

Electronically assisted, but still mechanically coupled for 99% of consumer cars. I've completely lost 12V on a car before and still managed to bring it safely to the side of the road.

Inifinity tried steer-by-wire but ended up retrofitting traditional hydraulic steering back.[1]

[1] https://en.wikipedia.org/wiki/Drive_by_wire

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#45

Post by stiglitz »

dsfyu404ed wrote: post #13
jtms wrote: post #9

Earlier quoted context omitted.

Coil spring + magnets = success?

You're fundamentally going to be limited by the fact that magnetic force is roughly exponential with regard to distance whereas coil springs are roughly linear. By stacking a bunch of magnets in the article they reduce the travel of any one magnet pair so it's closer to linear. If you look at short enough segment of a graph of an exponential equation it will look linear, this is basically what they're doing.

You mean quadratic, not exponential.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#46

Post by hinkley »

jaytaylor wrote: post #12
rrggrr wrote: post #2

Fully compressed I believe the opposite poles fields begin to attract each other, counteracting the matching poles repelling one another, and explaining the alternating pull force.

This is easily solved by including a minimal height spacer between the two magnets to prevent them from getting too close.

Strong magnets are fragile. There are warnings about letting them hit each other (managed to break one of the HDD magnets I extracted that way).

Elastomer bumper should do the trick.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#47

Post by croon »

mhh__ wrote: post #34
azhenley wrote: post #19

Earlier quoted context omitted.

About as scary as my Tesla on autopilot going around a curve at 75mph. Every time I ask myself, what if there is a bug or if it turns off...

You let it go round a curve at 75mph, or is this hypothetical?

I think he's referring to a curved piece of highway, not a turn.

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#48

Post by Retric »

weberc2 wrote: post #28
azhenley wrote: post #19

Earlier quoted context omitted.

About as scary as my Tesla on autopilot going around a curve at 75mph. Every time I ask myself, what if there is a bug or if it turns off...

Pretty much every critical system in a vanilla Toyota is already software-controlled, not to mention the legion of critical systems involved in air travel, elevators, medical equipment (e.g., pacemakers), etc. Not sure that this should bring comfort, but at least you need not be particularly frightened by your Tesla. :)

Elevators use simple physical safety systems.

Which is why you see headlines like: "Skyscraper elevator plunges 84 floors — and everyone survives" https://www.cbc.ca/news/world/elevator-plunge-chicago-1.4913...

Re: Can Repelling Magnets Replace the Spring in a Pogo Stick?

#50

Post by notacoward »

madengr wrote: post #42

Where does the heat go? The spring will have a much larger surface area to dissipate the heat. Maybe surrounding the magnets with a copper tube will conduct some eddy currents.

A lot of science museums have a display showing how magnets and copper pipes interact. In short, because of Lenz's Law, the magnet's motion induces an opposing magnetic field in the pipe ... which suggests another possible way to make a pogo stick with the right kind of resistance curve as well as addressing the heat issue.
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