PC Controlled Laser Turret / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

PC Controlled Laser Turret

1 2 next

Move Thread

LAN_403

uzzors2k

Tue Apr 07 2009, 07:47PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

As a side project I've been working on a PC controlled laser turret the last few weeks. The idea was to cheaply and quickly whip up some kind of turret with a laser mounted on it, so if I ever wanted to, I could experiment with laser tracking. I didn't succeed in doing it quickly, but it was done cheaply. The mechanical part was the most difficult for me, so I put the least effort in it.

Rotational movement is provided by two sets of gear assemblies taken from old CD-ROM drives, which are simply glued together. The laser was taken from an old laser pen, which also had a LED flashlight. The laser/LED assembly was glued to one of the gears. That constitutes the basic hardware, which now only needs some means of being controlled.

Given my conversion to AVR I chose to use the ATTiny2313 for this project. In terms of PC control I could use the parallel or serial port, but parallel is newb, and the AVR has a USART module built in, so serial it is. Some circuitry was made. More specifically I used a MAX232 to convert RS-232 level to TTL for the ÂµC, some gatedrivers for motorcontrol, and otherwise there's just support circuitry for the AVR chip. The firmware for the AVR does nothing but receive an incoming serial byte, do some rudimentary error check, and write it to portb. I used MikroC Pro to make the firmware, but given the code's simplicity it could have been done just as easily in assembly.

To ease steering the turret I also decided to make a dedicated windows application which could send the correct codes at the punch of a button. This was a first for me, and I made the mistake of starting with Visual C++, which blew me away. I now see why Visual Basic is more popular. After three days of work I churned out a simple little program far beyond what I had expected to achieve. It even gives error messages instead of crashing!

1239133003 95 FT0 Turret Software Screenshot

All in all it's a fun little gadget, but the gear reduction is too low so it's very jerky. I know servos are meant for this sort of thing, but I didn't have any. I'm not good at writing about projects after they're done, so do ask! Here's the firmware, schematic and software.
]firm_and_soft-ware__schemmie.zip[/file]

hotcrazyfruit

Wed Apr 08 2009, 01:52AM

banned on 5/26/2009
Registered Member #1877 Joined: Mon Dec 22 2008, 02:03AM
Location:
Posts: 147

what you should do is get an astronomy laser pointer and get rid of the current limiting resistor i it. then set stuff on fire. that would be impressive.

Dr. H.

Wed Apr 08 2009, 03:40AM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day guys

hotcrazyfruit wrote ...

what you should do is get an astronomy laser pointer and get rid of the current limiting resistor i it. then set stuff on fire. that would be impressive.

But be shure that the turret won't go crazy and set your house on fire hee hee

Are those DC motors that you are using for positioning ?

Cheers

...

Wed Apr 08 2009, 05:41AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

That is quite awesome! I agree though, you should steel a diode out of a fast (20x or so) dvd-burner and get a housing for it (you can get them on ebay pretty cheep, check out

for a ton of info on such projects) and increase the laser power.

As to the motors, it seems like you have enough gear reduction, you just need to slow the motors down. you could probably rig something with a resistor and a few diodes from the output of the avr, so that one pin gives default full speed and another gives ex 1/10 speed, and have 2 buttons on your program large step or small step.

uzzors2k

Wed Apr 08 2009, 06:13PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

I'm using 5V DC motors for positioning. With the voltage drop from the gate drivers the motors only see 2.5V. I've thought about different ways to get better precision, but as is the motors have very little torque. To the point that any further decrease in power would make them too weak to overcome the mechanical resistance from the signal wires!

I just purchased and received a PHR-803-T module on ebay, so we'll see about the laser upgrade.

Dr. H.

Wed Apr 08 2009, 06:42PM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Why don't you consider upgrading to steppers ? There are some very cheap half-step drivers that will give you very good positioning with some gear reduction, and you will be able to exactly point it where you want. Also you only need direction and clock signal for every stepper.

Cheers

Renesis

Wed Apr 08 2009, 08:20PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

Nice project, that is not something you see everyday.

You could use a couple of servo motors like those used on rc cars. They are both cheap and powerful.

Wouldnt it be neat if you could steer the turret with your mouse, like a first person shooter game?

ConKbot of Doom

Wed Apr 08 2009, 09:52PM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

Renesis wrote ...

Nice project, that is not something you see everyday.

You could use a couple of servo motors like those used on rc cars. They are both cheap and powerful.

Wouldnt it be neat if you could steer the turret with your mouse, like a first person shooter game?

and with a laser you could use the main laser itself with a few photodiodes as a home position setup... have it look up till the laser hits a photodiode directly above it to home elevation, and then rotate down 30 degrees and rotate till you hit one to home azimuth

hotcrazyfruit

Thu Apr 09 2009, 04:00AM

banned on 5/26/2009
Registered Member #1877 Joined: Mon Dec 22 2008, 02:03AM
Location:
Posts: 147

i just remembered of another way, you could use the same technology old ball mice use. having a perforated wheel, then a photo transistor and led . then mounting the wheel to the axel of the part that rotates and elevates the laser. probably use an IRED so it doesent glow) and have a circuit count the number of times the photo transistor receives a pulse of light. this could be used to calculate the angle of the laser, as long as you know how many perforations there are in the wheel. take apart an old mouse and see for your self, its actually quite a far fetched idea, and i was surprised when i took one apart to see that.

Ryan Parle

Thu Apr 09 2009, 01:37PM

Registered Member #2038 Joined: Fri Mar 20 2009, 03:39PM
Location: Bristol Uk
Posts: 60

One of my other hobbies is AstroPhotoraphy, and i have been helping a friend develop his own system for a motor driven encoded mount for his telescope.

We have actually used an old serial ball mouse to alow confirmation of the mount being in the correct position, we drive the mount using stepper motors ripped out of an old printer and the driver board is an Omnima driver board.

others have used the ardunio (SP) board to controll their mounts, in order to supply the current needed by the motors a seperate driver baord was made, i dont know the specs, but i would imagine for somthing as small as this project the it might be possible to drive the motors directly.

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob