Rocker Bogie-ish using rotors

[Curveball Anders]

As a long time Lego(tm) builder I esp like a 6 or 8 wheel rover/crawler design that more or less acts like a proper Rocker-Bogie (of Mars rovers fame).

It's a passive self balancing setup that keeps all wheels on the ground while keeping the body balanced.

I call it Slinky because what it feels like holding a small Lego one in your hand

I made a demo using freely rotating rotors.

Top and side view.

and in action it works like this:

 

My problem is that I can't find any way to limit the travel of the rotors, which creates a challenge on low gravity worlds.

It's very easy to leave the ground and then the rotors move freely and might (or rather will) land upside down, which is bad ...

Anyone having any ideas on how to limit the rotation or add some (weak) force keep the rotors back to center when the wheels are off the ground?

 

[sundog]

 Try adding physical stops then turning on same vessel interaction.

[BigFatStupidHead]

Can you use servos instead? They can have their maximum rotations set, and should work as well as rotors otherwise.

[AHHans]

10 hours ago, BigFatStupidHead said:

Can you use servos instead? They can have their maximum rotations set, and should work as well as rotors otherwise.

Well, the maximum range of the servos is not a hard stop, it only limits the range to which you can set the target angle.

But, yes, this is IMHO an application for servos, not rotors. If you set the target angle of the servo to the "neutral" (or default) position then you can use the maximum torque setting to set the "spring strength" that will return it to that position. I.e. if you set that to a low but not zero value, then it will return to that position if no other forces are present, but move fairly freely when there is an external force. Or if you set the maximum torque to a higher value then you'll have some kind of spring. (That will keep draining electricity, but well...)

[BigFatStupidHead]

I quite liked your design, and this is my quick take on it.

[GluttonyReaper]

Perhaps you could enable collisions on the moving legs, amd then create some kind of physical blocking buffers with cubic struts?

[Curveball Anders]

On 9/6/2019 at 2:56 AM, BigFatStupidHead said:

Can you use servos instead? They can have their maximum rotations set, and should work as well as rotors otherwise.

Did a rebuild with servos, limiting traverse to +/- 45, target 0, damping 1 and engine 1.

Worked beautifully.

Tonight I'll build a more functional and do some hi speed  testing on Minmus

 

 

Edited September 8, 2019 by Curveball Anders