Need a compact linear drive for a hexapod table

[some bloke]

TL;DR Summary

I am trying to devise a hexapod table with maximum movement but minimum space, and need an actuator to achieve it.

Hello everyone,

I'm trying to make a hexapod table, in the same style as this:

but I am trying to overcome the main flaw with this design - the minimum height being so high.

My goal is to produce something which someone can stand on, in their home. It needs to become as flat as possible, and also extend to around 1m tall. Essentially it will be the same, but it will need linear actuators which collapse to become much smaller than conventional ones.

I have had a look at Zip-Chain actuators, and thus far they seem the most viable, though they need a linear guide to work properly.

I am trying to find an electric actuator which isn't limited to roughly doubling its length - one like a telescopic piston, where it can achieve several times its own length, with precision in its movements.

Does such a thing exist?

 

[some bloke]

On further investigation I have found this:



It's the same principle but runs on a circular track to give the same effect, but with the added bonus of rotation, which I need to achieve.

I will be mucking around with some calculations and models but the low-profile I was looking for looks achievable with this, where a fixed position linear actuator will ever go so flat.

I might adapt the principle somewhat, but this looks like a good building block for me to work from!

Still appreciating any input if people know of things that I'll have missed!

 

[jim mcnamara]

I must be missing something.

Ladders, platforms, scaffolds, et al, have max load weight. Say 100kg. So the diameter of the platform has to have splay larger than the platform, and as the platform extends upward the mechanical advantage of our human payload of 100kg increases. So the distance from center for the lags has to be larger to start with. I.e., stability looks poor to me without that consideration.. You've seen tall A frame ladders? Theaters have 6-10 m A-frames to allow workers access to lights. The leg spread an splay are large for stability.

FWIW, your innovative approach should be commonplace if it has merit. Don''t you think? "Scissors" and cherry pickers as elevator platforms are common.

 

[berkeman]

Summary:: I am trying to devise a hexapod table with maximum movement but minimum space, and need an actuator to achieve it.

My goal is to produce something which someone can stand on, in their home. It needs to become as flat as possible, and also extend to around 1m tall. Essentially it will be the same, but it will need linear actuators which collapse to become much smaller than conventional ones.

Can you say what the application is, and why a more traditional method like the one below would not work?

 

[anorlunda]

It sounds like you're trying to make a motion simulator.

 

[berkeman]

Sign me up!

 

[phinds]

I've got an idea. How about we all take turns guessing just what it is he is trying to do?

 

[some bloke]

Yes, I am essentially looking to create a motion simulator, as a project to get my teeth into and learn about programming and interfacing real-world and virtual constructs, but also in the confined space of my own home, which is where the issue of the heights and widths involved in using linear actuators becomes an issue - as well as their price!

I am going to be making a small-scale model initially, what with the prices etc, and then once I've got the hang of programming it, I will move onto a larger project - I just need to make sure my small-scale prototype actually reflects the end result I'm aiming for, otherwise it'll be back to the drawing board!

 

[trurle]

Yes, I am essentially looking to create a motion simulator, as a project to get my teeth into and learn about programming and interfacing real-world and virtual constructs, but also in the confined space of my own home, which is where the issue of the heights and widths involved in using linear actuators becomes an issue - as well as their price!

I am going to be making a small-scale model initially, what with the prices etc, and then once I've got the hang of programming it, I will move onto a larger project - I just need to make sure my small-scale prototype actually reflects the end result I'm aiming for, otherwise it'll be back to the drawing board!

Hexapod table use a linear actuators, therefore intrinsically not a compact design. Gimbals (which use rotary actuators only) are intrinsically compact and are foldable to a flat panel when not in use. Disadvantage is what gimbals have only 3 degrees of freedom (rotation), but this may be ok for motion simulator.