Ideas for robot "gripper"?

[Haytham01]

Hello everyone.

Would you please suggest some ideas/mechanisms for a gripper?

It's supposed to hold a 0.75 kg box.

I know the 4-bar mechanism,



but I need some other ideas, because the 4bar is tedious to fabricate, and could not be aligned/manufactured easily.

So I really want to explore new ideas, do you have any?

Any help is appreciated.

thanks all

[Haytham01]

Any comment, description of a gripper, photo, link or anything is appreciated. Thanks.

[Cristi_Neagu]

Hi.

I recently completed a gripper design for a school project. If you like, i can post a inventor design of it. I also have an excel spreadsheet to calculate the dimensions of it and the gripping force.

[Haytham01]

Hi Cristi_Neagu,

yes please, I'd like to see others work. This would be so much of a help, pleae post it

[Cristi_Neagu]

Ok, here's the link:
http://laptop.crashboy.operaunite.com/file_sharing/

I'll keep the link up as much as i can. If you haven't been able to download it, let me know and i'll put it up again.

Since this was a school project, it's overly complicated. It uses linear ball guides, but you can use anything that slides on a rail. The guides this design was using stop the bushing form rotating along its axis, so if you use something that doesn't stop it form rotating, just use two of them, one on top of the other.

There is room for simplification, but the main advantage of the design is that the "claws" don't move in a circle, but along a line. That way you don't need to take into consideration the size of the object grabbed when positioning the gripper.

If you are interested in the design, i can also post the excel file used to calculate the geometrical dimensions of it (linkages dimensions, linear actuator ride, things like that). I need to clean it up, and make some better documentation for it.

Good luck.

[Haytham01]

This is a smart design, Cristi_Neagu. Good work. I liked it a lot.

The piston pulls the links, and the links make the jaws move along a linear path.
Very interesting. Thank you for sharing this great work.

I have a question please, does the piston move using 'Hydraulic cylinder' or what ?

[Cristi_Neagu]

Yeah... it was supposed to use a hydraulic cylinder as an actuator, but you can use anything: pneumatic cylinders, electric coils, rack and pinion mechanisms... even a bicycle cable. You can also add a spring for opening the jaws. Do note that it's not recommended to use a spring to hold the gripper closed, because they loose their characteristics in time, and would lead to inconsistent performance.

I think i might write a little tutorial on gripper design and post it on the SoR main site.... Will talk to Admin about that....

Good luck with your work.

[Admin]

The lazy man's gripper, brought to you by yours truely

Custom Robot Arm and Gripper Demo

[Haytham01]

That gripper looks cool, it's simple and effective.
Thank you Admin for sharing this

[Haytham01]

Please advice, everyone ... Is this gripper design good or not ?

It's composed of 2 jaws governed by spur gears, and the joint attached at the end of jaws are hooke's joint to allow the jaw to grip "inclined surfaces.

The grip is made a double-v blocks, so that to be able to grip cylinderical objects.

what do you guys think, advice pleeeeese ... It's for a part of my graduation project.

inventor render :

[Cristi_Neagu]

That griper design will work well with a small variation of object size, because the claws move in a circle. If you've calculated them for an object with a radius of, let's say, 50mm, then you'll have trouble gripping something with a radius of 75mm or 100mm.
But if your application only involves one type of object, and you don't need to plan ahead for other sizes of objects, then it's a good design, mainly because it's simple.

[Admin]

Instead of those complicated things at the end to conform to an object, just use squishy foam.

But I still say my gripper is better

[Haytham01]

Cristi_Neagu and Admin, Please advice on this

The Hook's joint allows the grip to be always along a line, see :





Do you think it's a good design, please tell me what you think.

[Admin]

I don't, because those little end thingies will just wiggle around. Nothing is keeping them aligned.

[corrado33]

I agree.  Now if they were somehow fixed to stay parallel to each other, then I think that'd be a different story.