Are there alternatives to a Stewart platform that have more lateral motion?

[some bloke]

TL;DR Summary

I am working on a project which currently is being designed around a stewart platform which is itself on an X/Y bed to give greater lateral motion. Before I go sinking time into this, does anyone know of something which behaves similarly to a stewart platform (6 degrees of freedom) but with emphasis on lateral motion instead of vertical?

As per the short description, really!

I'm working on a project which involves a stewart platform:

to give angles and vertical movement, but the main application of my design requires a large degree of lateral movement, about 4 times more than the dimensions of the top platform itself.

Before I start designing this around a stewart platform which is itself on a linear bed to give it increased lateral motion, I am curious whether anyone knows of a similar sort of device which offers greater lateral motion whilst still giving a reasonable amount of tilt, vertical motion, & rotation?

I personally haven't found anything, though I have a design I am considering which could be ironed out to sort of work - but if there is something out there and anyone here knows about it, I'd be grateful to see it!

 

[Baluncore]

Get twice the motion of a Stewart platform by mounting one platform on another.
Most of the combined middle platform is not required.

 

[Lnewqban]

Could the platform be hanging instead?
If not, but height is a limitation, it could be also mounted on an x-y sliding platform.

 

[some bloke]

I have considered hanging the stweart platform, which does help with vertical space as the load it on top and can be withn a ring which suspends the platform. My concern is that I will not be able to get the required lateral motion.

Mounting one atop the other seems like it will not gain me much - surely making one with legs twice as long will achieve the same thing?

I am considering whether I can use a mechanism to increase the lateral motion on the platform, such as adapting the mechanism of a cupboard oor hinge (whch allows the door to pivot around a point which the hinge isn't actually occupying) to mechanically imitate a wider bed without actually having one...

My other consideration is to design a stewart-esque platform which runs on parallel rails, so that the whole platform can slide together whilst the legs can be separated to adjust the height & tilt of the platform. Whilst it would behave differently to a stweart platform, it should be programmable to give the tilts and height adjustment that I am looking for!

 

[Baluncore]

Mounting one atop the other seems like it will not gain me much - surely making one with legs twice as long will achieve the same thing?

At some point a limit to the angle will be reached when the legs and joints are obstructed. You can get twice that angle with a stack. Distance limits depend on the actuator long/short ratio, which has not been identified.

 

[some bloke]

At some point a limit to the angle will be reached when the legs and joints are obstructed. You can get twice that angle with a stack. Distance limits depend on the actuator long/short ratio, which has not been identified.

Ah I see, I was thinking of it as a parallelogram, rather than of tilting the first platform in the intended direction, then tilting the other in the opposite to kink the mechanism in the required direction!

Thanks for the help!

 

[some bloke]

Currently consideing this approach, with the 6 feet driven independantly up and down the rails. This is a crude model, the final one would be designed to drop to near enough just above the rails without the arms clipping into things!

Maximum height will be the triangle formed when the two pairs of arms are positioned parallel and directly below the joint. Maximum working range (when at lowest height) would be the full length of rails less the length of the platform assembly. I will need to do some working out to figure out the maximum range in the direction perpendicular to the rails!

Only concern is that the machine might jam up, but I suspect I can make a very basic prototype with wood & rollers to see how it will work out, and what its limitations will be! Might even be able to make it from lego technic...

 

[Nik_2213]

Tangential:
"... the mechanism of a cupboard door hinge (which allows the door to pivot around a point which the hinge isn't actually occupying) ..."

Due care with the kitchen variety, please, as their multiple hinge lines may give a lot of flexure / lateral play...

I've tried to mount a 1/4 carousel under sink drainer behind what had been a dummy drawer front, but 'wibble' in its two near-adjacent hinges let it sag beyond the limited clearance...

;-( Could not use 'roll-out' as would clash with nearby laundry machine. Junior Cat claimed carousel module while I sought options... )

 

[Tom.G]

Tangential:
"... the mechanism of a cupboard door hinge (which allows the door to pivot around a point which the hinge isn't actually occupying) ..."

Design reference please!

 

[Nik_2213]

https://www.amazon.co.uk/gp/product/B0916VW1YX/

IIRC, many aircraft & spacecraft have similar hinges to swing thick hatches / hatch-covers aside.

 

[boggers]

Hi, first post on these forums, came here searching for more info on circular base Stewart platform, I guess we have similar projects in mind but I've just started, so you're much further along.

I don't know how much lateral motion you are after, but since you were already looking at circular base Stewart platform... have you considered simply mounting the Stewart platform base on 2 drive wheels and a couple of casters, I guess similar to a Roomba? Then your lateral motion would only be limited by room size. You could maybe account for any inaccuracy of the wheels in the motion of the Stewart platform itself. Just a thought.

I would love to hear more about your project, I'm designing a little test thing first with a view to eventually making an "arcade grade" 6DoF motion sim.