Well more seriously, I wanted to experiment some algorithms of stereo vision such as the disparity map, so I decided to buy two cameras and to hack them to install them on the robot arm.
That way I wish I could try some algorithms and maybe go further deep in artificial intelligence experimentations I started a few years ago ! If you want to know more, just have a little break and go to my blog in which I give some more details on what I do... Here is the link : http://aiaddict.wordpress.com/
Before to start collect the stuff and tools you'll need :
- Allen keys
- A flat nose pliers
- A (strong) cutting pliers (yeh, I said a strong one ! Not a nail-clippers ok ?)
- An aluminium hanger (weird, I know but you'll see that's the perfect stuff to do the job !)
- A little flat head screwdriver
- A little cross head screwdriver
- A ruler
- 2 Logitech C525 webcams
About the last point, I chose this webcam because it's an HD webcam featuring auto focus and small form factor, with low mass and also because it's not that expensive for the image quality it gives.
Of course, this hack only makes sense if you also have those same webcams... Ahem...
WARNING : THIS HACK REQUIRES UNMOUNTING AND HACKING THE WEBCAMS. BY FOLLOWING THIS INSTRUCTABLE YOU AGREE THAT THIS WILL VOID THE WEBCAM WARRANTY. YOU AGREE THAT YOU FOLLOW THIS INSTRUCTABLE AT YOUR OWN RISKS AND THAT I CANNOT BE RESPONSIBLE FOR WHAT COULD RESULT FROM THAT. Thank you.
I apology for this sentences but I want anybody who wants to give this a try to be aware of the risks. Let's follow !
Well, talking about the final result, on the top of this page, you can see what the hack will look like once it's been done.
As you can see, the webcams are perfectly installed on the robot arm, on the gripper to be precise.
The most interesting point is that you still keep some camera movement to make some image adjustements (height and orientation).
The other good point : it doesn't reduce the wrist movement amplitude.
Is that what you want ? Ok, let's move on to the first step !
Step 1: Prepare the Aluminium Hanger
The hanger is to extract two little aluminium rod out of it. These are going to be the frame to support the webcams and to attach them to the gripper.
CAUTION : Please first make sure that the rod diameter is in the 1.5-2mm range ! Otherwise it's not going to work with the cameras rotating system...
So take the hanger and cut on each side of the bottom part as shown in the second picture. This gives you an aluminium rod.
Next, cut the rod in approximately two equal parts. It should give you what's shown in the big picture.
Step 2: Bending the Rods
Start first by making a half buckle as shown on the picture.
Now, you can have a preview of what you just did by presenting the bent rod to where it will be placed.
To do so, just unscrew the three (maybe four) screws of the grippers (the ones with black plastic nuts).
Just leave them unscrewed enough to allow the rod to fit as shown in the second picture.
If you did well, it must look like the third picture.
Once it's ok, make a mark on the rod where you'll have to make the second bend.
When doing so, you have to make sure the buckle is clearly well locked by the screw by slightly pulling up on the rod.
Step 3: Second Rod Bend
Now use the flat nose pliers to bend the rod another time as shown in the main picture.
As a hint, if you use the same marking as I did, you'll have to hide the mark with the pliers nose to have a correct bend.
I made the mark a little too low, so it did not fit quite well when put on the robot...
The best thing you could to is to use the main picture as a reference. This one is the final bend I had working perfectly.
It all has to be well done. Everything has to be planar and with good bend angles, which is easier to say than to do...
Note that the angle between the rod tail and the ruler is not 90°. That's to compensate the way we mount the rod on the robot arm.
In the end of this step, you should be able to mount the rod as shown i the last picture without forcing while doing so.
Step 4: Last Rod Bend
So, now bend the rod as shown in the pictures.
As for the other steps, you can try mounting the rod on the robot to see if it fits and make some corrections if it's not.
Ok, now you spent hard time bending the rod, I just let you remember that we don't want our robot to be Cyclops, so that you have to spend another hard time doing a second rod bend !
Eheh ! Don't worry ! You did it once, so you can do it twice !
Step 5: Webcam Stand Hacking
First, start unboxing the webcams ! Now you got it on hands, it might look like the picture above.
Step 6: Removing the Webcam Stand
So well, see this orange strip ? Well remove it by slipping your little flat head screwdriver in the small interval on the right or on the left of the strip. You may be able to obtain what's shown on the second picture.
At this step, be careful not to put your fingers on the strip bottom, the side with glue in it, because you want to put it back afterwards to have a clean fine don't ya ?
Using the same method, remove the second orange strip of the webcam.
Step 7: Removing the Stand Cover
Unscrew both of them.
Then, using the flat head screwdriver, as shown in the image, remove the stand cover.
It may require a little force to do so because as you may have noticed, on each side of the screws, there's a molded plastic lock.
Don't worry, you'll still be able to screw it without a problem.
Now you did it, remove the second cover as shown in the last photo.
Step 8: Unmounting the Stand
Remove the two pieces of plastic which are in between the two branches.
Take a few seconds to give a look to the hinges. They are different and the have to be mounted on a special orientation so to work and fit on the webcam ! Please not this point in somewhere, so you'll mount it on the right side when it'll be time !
Step 9: Hacking the Stand
To do so, using the flat nose pliers break both stand branches as shown.
Try putting on one side the hinges.
Then, pick up your (strong) pliers (that's now it has to be very strong, and you too, "use theee... the fo... the fooorce Luke !!") and cut the rod as shown.
You may now be able to remove the hinges.
Step 10: Reusing the Hinges
Take care of the side ! As I said before, hinges have a right side you should take care of to have your webcams installed perfectly and in the right side !
Once done, install the hand made hinge on the webcam and screw it.
Step 11: Remounting the Webcam
Put back the bottom webcam cover and screw it.
Now you can put the orange strips back on their original place !
Hehe see ? As if it just left the factory ! Professionnal hack !
Step 12: Final Mounting
Mounting the webcams on the robot hand !
Now you can have a preview of what the webcams see with some software and adjust the positions and orientations to you requirements !
You also have to arrange and attach the cables on the robot frame to avoid knots and other issues.
So here we are, I hope you managed to build it and that everything went good ! Hope it helped someone !