The Snatcher from the Discovery Book
This autonomous robot finds, grabs and lifts objects, and it is featured in Chapter 13 of the Discovery Book. The robot is heavily popular among MINDSTORMS builders. It is especially used frequently in robotics competitions because of its versatile grabber design.
The Snatcher grabs and lifts objects with just one motor
Building and Programming this Robot
Instructions for building and programming this robot are included in The LEGO MINDSTORMS NXT 2.0 Discovery Book. It can be built with just the pieces in the NXT 2.0 kit.
could you please specificate on the stps with the suitcases?
Every programming step comes with illustrations that you can replicate to make it work. If you’re having trouble doing this, you can also download the programs from here.
thanks a lot!!!
Hi i´m from Peru and its hard to buy the discovery book because i don´t know how to shipping it. So my question is if there is another way so see how to build the snatcher because is the only robot that i want to build and i can´t do it by myself. Thanks and excuse my bad english.
in the programming software it does not have closest in the variable.
Wow you did a really nice job! Why don’t you check out my grabber and lifter I built: http://nxtgeek.blogspot.com/2012/06/mobile-skid-steer-arm.html
I’ve seen it on the NXT Step (so no need to post here), and it looks nice. Shouldn’t hurt to list BobBot in the credits though
Thanks! And I wasn’t telling you so you would post it on your website I just wanted you to see it. I actually that was my own mechanism I didn’t even look at how the Bobbot was made before this
Hi Laurens,We followed the instrutions from book and built the snatcher and the program, but it didn’t work as it was supposed, it alwsys trys to grap something else which wasn’t there; finally I loaded your program, it still won’t work, and it did same thing. We couldn’t figure out what went wrong, could you give some directions where to check.
thanks
Use the View menu to see if the sensor on port 4 can detect the object you want it to grab. Also, the object cannot be too far away or the sensor will not see it. That will help you determine whether the problem is in the program or not.
Hello Laurens, I’ve seen The Snatcher a couple of times now around the internet and I want to build a robotic arm out of Lego Technic and Mindstorms. So I think the ‘claw’ of The Snatcher is the most suitable for my project. The problem is, I don’t want to buy the whole book, only for the claw. Is there any way to get the instructions for the claw itself only? Thanks in advance, Bob
hi Laurens valk I like your snatcher but what does the ultrasonic sensor do?
It looks for the Higgs Boson.
what is the higgs boson?
It’s a magic new LEGO piece. It exists in theory, but they’re still trying to figure out how to detect it with an NXT robot.
Nice one.
Oh.
My child snatcher assembled in Chapter 13. Children will not be able to put together a program still small. I do not know what do I enter a number I want to download the program there.
Please tell me how I can understand a child can not be confirmed at this fine eye disease now.
I do not know how do I enter a number or character download site but also Uchikomeru digits can be displayed.
We have created a site in question translation
If you have any problems logging into the site, email me so I can help you.
We will e-mail Thanks
I found the answer to your question
Thank you
Wow its awesome. Pick up the object and lift it perfectly.
maybe you could let people download the program right here, on the website.
That’s already possible
i have the book but i cant make the paper rings.
If you can build robots you can make some simple paper rings
You can also use the cardboard rings from toilet paper, whatever they’re called in English.
Hey, is there a way I can buy only the instructions of The Snatcher? I like it very much, but I can’t buy the whole book. Thanks!
Nope, that’s not possible. But the digital book is only $13.79 on Amazon. That’s less than 5% the price of the $280 NXT.
how did you get a restblcok???? i can not find it!
If you’re having trouble programming the robots, you might want to read the first chapters first and move on to Chapter 13 later
You can also just download the programs (Use the menu at the top of this page).
I tried to log in but it just cleared my work please help
I was making my snatcher with my brother but at the end we had a problem the claw closed when it was down
And opened when it was up we need some help
Check out the illustration on page 224. It’s important that everything is aligned exactly as shown in that sideview. Note that the claws are opened (not grabbing something) in that side view.
I’m 99% sure I programed my snatcher right but it only spins around and dose not move closer or try to grab or ANYTHING
Alternative program for the snatcher:
http://www.box.com/shared/e3o3venu3t6r738u5lat
This version doesn’t use the rotation sensor to get back to the closest object, but actually scans it using the ultrasonic sensor and the previous stored distance.
With some fail safe mechanisms. Works like a charm
Björn
I built the Snatcher (from the NXT 2.0 Discovery Book), and have run into a problem I can’t seem to fix. It goes through the motions of finding the object (a colored paper tube), but never seems to actually recognize it, completing 2 180 rotations and dropping its arm at a random location. Upon cross-referencing my code with the sample your website, I found that both programs were identical, and the official program encountered the same problem. Any ideas from people who have built it would be greatly appreciated.
hi good day im trying to assemble the snatcher out on you tube and
your site is there any possible that i can bet a copy on how to assemble the snatcher thank you and good day