Thanks to the posts on this forum I have modified a simple grabber that I want to put onto an NXT line follower robot to grab a soda can (I still need to play with the design to put rubber grips on the inside of the jaws and try to fit a touch sensor in so it knows when it has shut around it). Once it grabs the soda can it needs to lift it approx. 10cm off the ground, locate a red block, move to the red block and sit the soda can down onto the red block. I'm wondering if this grabber can be incorporated into a forklift-like mechanism so it can be lifted vertically without tilting the soda can backwards. I was thinking it would make setting the soda can down on top of the block smoother and more precise than something that lifted it up and down in an arc. If anyone has any good ideas I'd love to hear them.

Thanks in Advance,

Simon

Nice grabber!

Your project reminds me of the old barcode truck that Lego released in 1997; http://www.bricklink.com/catalogItem.asp?S=8479-1

Though this one grabs tires and mostly round objects and tilt them backwards, it should be worth looking into for some inspiration.

There's plenty of ways to elevate a grabber up and down, and I would think that a forklift solution as you say, or some linear actuators would be the most sturdy and accurate way to go.

Hi,

I'm currently working together with Alasdiar on the instructions for such a model using only 3 NXT motors. It is an updated version of this one :

also build by me.

Instructions should be online within a week.

Ramacco

Thanks 'OleBM'... I've been trying to work out how to fit a linear actuator (a D.I.Y. version) to lift it high enough without disengaging the gears on the jaws.

Ramacco, this looks excellent. Do you mind if I look at your instructions and share them with my students (I run the lego robotics class at the school I work at), when you post them online to give the students some extra inspiration? Those Mindsensors look good ... good prices too when compared with Lego sensors. The only 3rd party sensors I've played with are HiTechnic ones. It looks like these can be programmed using NXT-G too... great for us beginners who are just learning about RobotC.

I should also mention that I have height and width parametres to work within. The robot can't be more than 270mm high and wide.

Edited February 26, 201312 yr by TasV

Do you mind if I look at your instructions and share them with my students (I run the lego robotics class at the school I work at), when you post them online to give the students some extra inspiration?

That sounds familiar.....

Edited February 26, 201312 yr by Alasdair Ryan

No problem..

You don't need to spend the money on the mindsensors, i'm only using nxt motors.

Send me an email or PM and I'll send them to you when they are ready.

Ramacco

Thanks 'OleBM'... I've been trying to work out how to fit a linear actuator (a D.I.Y. version) to lift it high enough without disengaging the gears on the jaws.

I should also mention that I have height and width parametres to work within. The robot can't be more than 270mm high and wide.

Linear actuator-speaking; I don't think the Lego standard ones would be the best alternative. If you're looking for actuators with long extension capacity, and don't have the room for the motors driving them, you should look into these: http://store.firgelli.com/SearchResults.asp?Cat=1822

These would come in handy for you, especially if you're gonna use NXT.

I've recently ordered a couple of these myself, not for robotic use though, as my strong side is vehicles :-)

Ahhh.. that's right... the motors have built in rotation/angle sensors don't they... I'll get the PM sent off tonight.

OleBM... I'm either making my own linear actuator (simple one with worm gears) or using a 13M rack to make a rack and pinnion style lifter. Whatever it ends up being needs to be simple for the kids to make so they can take the idea and run with it to make their own vesions of it. I'm just trying to put together a mock-up of a few different mechanisms they can then use when they create their own designs. I've looked at the Firgelli ones before and love the look of them. There are a few youtube videos of grabbers using these as well... they have an extra long reach. My budget won't stretch far enough to buy these for each group of students, unfortunately.

For some reason (maybe cos I'm a newb here) I can't access other member's profiles to send PM's or see email addresses. My work email address is simon.voorwinde@education.tas.edu.au if I can ask the plans be sent there.

Cheers,

Simon

Edited February 26, 201312 yr by TasV

I have made a few LA's from scratch you can see them on my Youtube channel.

Simon, i'll drop you a picture in your mail tonight!

The mindsensor glidewheel does provide encoders for PF motors.

I really appreciate your assistance, thank you!

I was looking at this LA last night actually!

Nice and simple!

Edited February 26, 201312 yr by TasV

Simon, I get a message that your e-mailadress is invalid.

sorry... I typed it wrong... it should have been simon.voorwinde@education.tas.gov.au ...

Edited February 26, 201312 yr by TasV

Email has been sent.

I'll update my EuroBricks posted once everything is finished.

Edited February 26, 201312 yr by Ramacco

Ramacco's grabber is a simpler, much better, design and is lighter on the lift-mechanism. We've made a similar one now and are trying to work out how to attach it to a lifter of some kind: (click for full size. Full LDD here).

I'm kind of stuck on how to attach the motor to the grabber and have resorted to buying a small power functions motor to install directly onto the top of the grabber so that the flexible cable can go up and down with the grabber. Is there a better way to power the grabber so I don't have to install it directly onto the top of the grabber? We used 6M cross-axles at the front so we can add ultrasonic sensors and/or touch sensors to the grabber.

Edited March 2, 201312 yr by TasV

Can pneumatics be used with NXT 2.0?

@ TasV: Yes, Lego Pneumatics can be used with the Lego Mindstorms NXT 2.0 -- see this TechBricks.nl webpage for ideas.

Hi,

I'm currently working together with Alasdiar on the instructions for such a model using only 3 NXT motors. It is an updated version of this one :

also build by me.

Instructions should be online within a week.

Ramacco

Ramacco,

I have been looking at your grabber and still don't quite know how to accomplish what you have done.

Would you be willing to share the instructions?

Thanks