Stowaways 3DOF Project

At the moment its all very much a dream.

I am copying Aldoz's design with a few tweaks.

As the center Strut I am using a Falcon Suspension Strut, the spring's tension is way to tight at the moment, so we are going to adjust it and plan to make it adjustable so we can adjust the tension to get the perfect amount of spring.
Im guessing i need the spring to be stonrg enough to hold it up but only just, so the motors dont have to do too much work to pull it down.. That will be a bit of guess work.

I bought a Uni Joint which is a bit smaller than Aldoz so im hoping that it can hold the weight and I dont fall off on my ass.. We have made up some connections (as seen on the picture) so it will unscrew off be removable.

I am planning on everything being able to be unscrewed for transport or storage.

its still a long way off because I'm relying on a friend to do all the welding work.

As far as eletronics go, This is the part that im really starting to enjoy. I have never had anything to do with embedded MCU's before but I'm learning specifically for this.

My plan is to program using the Arudino board but directly to the AVR chip (just using WINAVR). I actually dont know how to do PWM yet, Ive just learnt how to receive the signals from serial in binary format, I think I have a good method for PID but we shall see, I'm building Tronics H-Bridge and starting to research PWM, then I'll put it all to the test.

Ive got the fall back to use the JRK boards if I fail miserably, But If I dont, I will be sure to post al my source on here.

I'm also planning to use 3 of these as my motors,
just trying to get a better deal by haggling for 3.

If anyone needs any in Brisbane or GC wants to buy some too we can try and use buying power for a cheaper deal

http://www.princess-trade.com.au/cart/1 ... winch.html

Another aussie built sim project.....good to see... :clap:

Excellent you seem to be well organised and moving quickly, cant wait to see another 3DoF theres not many.

Hello! In first really good luck for your project!

Watching your spring I think this is really rigid! I haven't your spring specs but I think that when your platform position will go to minimum height position so your motor will suffer very much! and they will ask a lot of amps to beat the spring resistance!!

For let you understand well what I mean :
If I mount your spring in my 3dof so I will obtain my motors suffering really bad to make my platform going to minimum height position and the motors would ask too many amps for jrk12v12.

Just speculating, looking this spring and thinking about the calcs about my spring, I can say that probably your spring need a value from 2000N to 3000N or over to be pressed of 30 centimeters.
This mean your motors (the sum of your 3 motors)must to develop a value from 200kg to 300kg to push this spring to 30cm. I think from 30 to 60 amps (or far over)to do that.
Using jrk12v12 this configuration will be impossible but I think I already read you are NOT using jrk12v12.
I must to do a lot of calculations about spring because jrk12v12 it's a weak little motor controller, born to give 12amps continuus. So I (and all people using it) must have a lot of attenction to avoid to burn or warm too much this little motor controller.

If to reach a point you need 50amps so you need to know If your motor controller and your motors can handle these amps. IF your motor controller or your motors can't handle that you must to change spring to one more soft.
If your motors can handle these amps you need to check too if they suffer too much and warming too much.. in this case too you need to change spring into one more soft.

Sure I haven't your spring specs, just looking and speculating from the photo of your spring.
Can you say me the free lenght and the diameter of the wire of your spring? (the diameter seems to be 10mm minimum..)

For now again compliments for the accepted challenge of build a 3dof!! :clap:

A pneumatic spring would be much better. A reservoir to hold a larger volume of air, and a pneumatic cylinder to hold the platform up, would make the lift force nearly constant throughout the whole range, while a coil metal spring will become harder and harder to compress the more it is compressed. The servo could be completely unloaded throughout the whole range.

Hi. The spring is for a car and currently it would take about 500kg + to push it down.... it does not move at all when i am pushing it.
But we are going to cut the spring, so it has more play. and I am hoping to get it so it just holds 100kg up, but 110 kg will pull it down. So the motors will only need to be pulling 10, or 20kgs to get it down... This is all guess work, and if I need to replace the spring I can..

I dont have any spring specs as its just from the suspension that it came with it So its designed to go with a 2 ton car.

Yeah, I ahve thought about this. Except this will ad more expense to the project.

Can a Pneamtic spring lift 100+Kg up and down easily? Perhapes this could be a way to get a very large movement up and down. .except at the moment the expense is too much for me.

If the piston is large enough it can easilly lift 100 kg at low pressures, and can be calibrated for any weight you like. I don't mean to use it as actuator, just to replace the spring that relieves the actuator. If my calcs are correct, a 50 mm piston will lift 100 kg at ~5 kg/cm2 pressure (~71 psi). It'd need a reservoir for the force to be constant though, or the air will compress too much in the cylinder. I'm thinking of using pneumatic cylinders to relieve the vertical axis on my rig if I add vertical lift.

Hopefully I should make some progress on building tomorrow, if I can convince my friend to put in some hours.

I'm just working out a few issues with my programming and I will post the source soon.
I'm hoping for it to be a cheap and easy solution for anyone to use. Hopefully solderless too, but I'm not against a bit of solder.

Here is an update of how my electronics is going to work. I have 0 pins left to play with.. The H-Bridges I am sourcing on Ebay seem to only have 1 direction pin not 2.. I only need the push buttons during a setup section of my program so I Can use these pins if need be.

Should I have any capacitors to smooth out the Pots or can they connect directly to the Adudino board?

Hi Guys,

Just a Project Update. I have got my Volvo Speedo Working with an AVR chip.. have a look at the video here:

http://www.youtube.com/watch?v=hLpAxpFm ... e=youtu.be

How many Speeds/tachos etc can i make use of (i have 7) I also want to change the skin of the speedo, I need some sort of Dark Plastic that I can either print on or stick a speedo picture on.. I wnat it to be slightly transperent because I am going to put LEDS under it.. any ideas what I can use?

Just updating my progress, hopefully to receive some opinions.

My progress has been very slow because Ive been waiting for parts.

So far I have just finihsed the middle piston. I have a Gas Struct that screws into a tubing at the top and down the bottom. The Gas struct can apparntly hold more than 300kgs except I was worried that it was too thin to handle the movement and would bend. So we made a casing for it.

The Uni joint screws into the connection on the casing. The Gas strut is in the middle of it so I am hoping it will have a fast enough reaction time so the motors do not struggle (we shall see).

I finally got my bucket seat today, so the frame and everything should be made within a week, and then its just upto my own circuit design.

hi stowaway, I understand your feel while you are waiting parts to be assembled.. you need to have patience and you will face a lot of work but if you continue to work and work so you will get great results! Avoid to have hurry.. it's a bad enemy!! (Tomorrow I will touch 1 year of work!!!... )