4 bar linkage gripper compared to other grippers..advantages/disadvantages

Femme_physics

I'm trying to figure out info about 4 bar linkage.. I've ended up reading some technical info but nothing specific about parameters I need for a project like accuracy, reliability, cost.. etc. compared to other gripper mechanics (like parallel guidance and angular grip)

Does anyone have possibly helpful resource or feedback about it?

I like Serena

I think you need to expand a little...
What 4 bar linkage are you talking about?
Which alternatives are you considering?

Danger

I'm glad that someone else said that. I haven't responded to this because I thought that not grasping the question would make me appear stupid. I know of several different types of 4-link set-ups, and only one of them seemed appropriate to this case. The problem with that is that a 2-link would be moreso.
I prefer a parallel straight-line system for a gripper. Like a carpenter's wood clamp. The problem with a 2 (or more)-link as I see it is that it moves linearly while closing, which then has to be compensated for by the rest of the arm receding. The clamp type just closes on the target with no adjustment.

Femme_physics

The alternatives are parallel guidance (with a double threaded spindle) and angular grip, the most basic one

Lemniscate guidance in the added pic

Yes, so far we got

parallel guidance: more expensive, more accurate, heavier and bigger than angular

Angular: less expensive, less accurate, lighter and smaller than parallel

And the 4 bar linkage is kinda in between-- I think so anyway. We're making lots of educated guesses. I was hoping for some verifications.

There are 2 more aspects though we are considering - credibility and performances. I'm not sure what performances mean -- it probably contains a lot of features like velocity, chances of breaking down...etc

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Danger

That is unnecessarily complicated. I use two guide rods with a single lead screw in between them. It's very cheap and simple.


edit: Hmmm... I should perhaps ensure that you meant what I thought that you did by the term "double threaded spindle". I took it to be parallel jaws with 2 lead screws controlling them. (Nothing in your illustration looks familiar to me.)

Femme_physics

No, Danger, I mean somethiing like this where the motor runs the entire motion directly:



If you're referring to this I don't see how it's "unnecessarily complicated"

Danger

I now understand what you meant by "double threaded". I've used that, but only for scissors mechanisms.
I'll get into Inkscape and draw up what I'm talking about. It's a screwy process, because I have to take a picture of the screen and upload it to ImageShack. There's a strong possibility that what I have in mind is too primitive for your purposes, given the complexity of the one in your post.
Bathroom first, then drawing, then I'll get back to you.

edit: Change of plan. Sleep first, then drawing, then I'll get back to you.
Actually, I probably don't need to draw anything. I might be able to modify your picture with words. Think of your left-hand jaw as an immobile part of the framework. The right-hand jaw is on a single threaded lead-screw. There's no need for the bearing block in the middle.
That's a mighty peculiar pair of jaws in your picture. Ugly as hell, but efficient.

Femme_physics

Ohh..neat. :) Well if you had solidworks I could've loaded the software file ...I like the initiative, at any rate. Keeping a close watch now

Danger

Well, as I said, I have to sleep first. I don't know where you are, but it's 6:45 am my time, and I've been awake for almost an hour only because my cat jumped on me. I went to bed at about 3:00.
Catch you later.

I like Serena

Any news?
Did you already make a selection?
Or better yet, did you draw something in solidworks?