THMMY.gr

Hi every body, sorry for writing in English, my Greek is pretty bad.

I am building now prototype for my robotic modular arm, https://www.youtube.com/watch?v=kesImjNqyN0

I finished to build it and its work now manually with up-down switch for each piston. I would like to connect it now to computer and i need a student to help me with this.

(i will pay of course the expenses and some small amount for every work hour)
So, if somebody interesting, please let me know.

(my place is in Ippokratio)

I am available in the email, skype (elisom) or on mobile 6948036444

Thanks a lot
Eli

If you got plain switches to handle, you will need extra hardware, e.g. a microcontroller that connects to PC.
You have to figure out the response time that you need the arm to have. It is affected by communication to PC.
Depending on how many switches and how fast communications you need, the microcontroller will be chosen.

After that, you have to decide where you will close the control loop of the arm. That is, how will you know where the arm, or its end, is? Will there be a controlling algorithm written in microcotroller's embedded code or will you write a driver on the PC? That design choice is affected by the communications in a recursive style.

Anyway, my guess is you will be carefully ok with an arduino and even better with a raspberry pi.

Thank you very much.
I guess the code will be on the PC and i will buy all the hardware that needed.

Until now i finished only the hardware and the base electronics.
(http://armaxy.com/armaxy/IMG_20160919_174234.jpg)

Whoa, it's big :)
Congrats for building it.

So, you have 8 switches. That means you need 8 pins of the microcontroller. These output pins drive the switches with the help of transistors in a switching circuit.
Set the arduino at 1Mbaud, and talk to it via USB with a script on your PC (virtual buttons or commands) and you are set.

If you don't mind me asking, why do you need this?

Right now i have 8 switch with up/down/neutral.

I am doing it as prototype for my patent.

Check the YouTube up

 

Oh, so the switches can go up, neutral or down... This means you need 16 pins. Not really a problem.

I am not sure that 16 is enough but i don't have any experience. right now every switch have 6 connections so it is 48, but i guess it can be done also with 16

6 probably means 3 pairs of short-circuited contacts
1-up
2-Vcc or Gnd
3-down
You need to control 1 and 3.
So, 2 pins per switch, total 2*8=16 pins to be controlled.

The pistons works with DC, up - when + connected to + and - to -, and down when the opposite, so i think need 24 switchers to control, but i am not sure. 

Anyway i still looking for somebody that wants a bit work...

Then you don't need plain switches but h bridge ICs to control the motor direction.
If you use only switches you'll burn them.

Yes. i using 6AMp  dc so simple switch will not work.

maybe something like this (http://i.ebayimg.com/00/s/NjAwWDgwMA==/z/IBkAAOSw7FRWXPNz/$_12.JPG?set_id=880000500F)

i guess this one is good
http://denkovi.com/usb-16-relay-board

I don't like relays... Too slow, too much space and too much power consumption...
You built a robotic arm, not a crane, right?


Well, it depends on what the use is...

There is no use for it... It's just an ProtoType.

What else can i use?

personally I like darlington resistors (ULN2003 and such) for such operations.
if the pistons require lots of amperes to operate (darlington operate well up to 1.5A and 50VDC typically), then you might consider other, more potent, power switching transistors

It just came to me, do you have a power supply beefy enough for all those 8 heavy duty motors? If it's enough only for 1 you have to make a controller to operate them sequentially... It is going to cost a lot.

If you choose the relays and usb, make sure to operate the motors one ar a time or you'll fry the PS.

Really big stuff for a prototype...

The DC power strong enough for all the 8 together.

What is the ULN2003 ?

What's the model of the actuator? Just to check its current consumption.

I have 8 actuators
http://www.ebay.com/itm/Multi-function-Linear-Actuator-Motor-DC12V-150mm-Stroke-Heavy-Duty-500N-HG-/121910665213?hash=item1c62711ffd

ok, here
https://www.aliexpress.com/item/Multi-function-Linear-Actuator-Motor-DC12V-150mm-Stroke-Heavy-Duty-500N-load-mini-electric-linear-actuator/32610427135.html?spm=2114.40010308.4.9.vbmWrL
is the same motor but with its characteristics written.

Those
-Continuous Current(A):3A(max)
-Voltage(V):12v
mean that for 8 of them you need a power supply of 12V and 3*8=24A, do you have one such?

Also, now that we know the motor's characteristics and the fact that there are no electronics present whatsoever , the problem is fully defined and people can think of solutions.



PS If the idea is to have it work as modular, it is imperative that the design of the actuators driver/controller is to consider sequential driving of the actuators

Right now i am using 6A and it works well. however, i will put separate DC supplier to each module (each 4 actuators).

the stage now is to connect them first to the computer, but no idea yet exactly how.