I am working on a project in which we are designing a robotic arm that can be mounted to a wheelchair and will pick items up from the floor. We would like to use a three-fingered end effector in our design but would like to purchase one rather than design and build it. I am new to the field of robotics and seem to be having a hard time locating a three-fingered end effector. I was hoping that someone my be able to provide some suggestions.
Here’s what you definitely shouldn’t use…
A gripper from one of those arcade games.
Those things can’t even pick up a stuffed Shrek.
I haven’t seen an affordable (<$200) tri-gripper, but I’ll keep an eye out for ya.
What kind of items will the hand need to pick up? Robots work best with a well-defined problem.
The Robosapien has a three fingered hand, but I suspect you’re looking for something more substantial than that.
BTW, if you end up designing a gripper on your own, a quad-gripper would probably be simpler than a tri.
90 degrees is much more easier to work with, than 120 degrees.
The gripper will be picking up small objects which the wheelchair user may drop such as a pen, a piece of paper, or a book. The max will be about 3 pounds.
Nick, you say that you haven’t seen an affordable tri-gripper but I assume from the context of your reply that you have seen some that may be costly. Where have you seen these?
I’ve been studing the photo of that Robotis 9 DOF hand, it looks as if it uses somethng very similiar to the Lynx ASB11 brackets.
I bet with some better documentation we could come up with something just as good built from Jim’s stuff for much less than $3900!
I’m going to e-mail them and see of I can finagle some sort of assembly guide from them and see what we could make.
Tinman
you might ask what the $3900 is actually buying. If it is just the end effector then you are quite right in going for a home built. If it has sensors built in and control software designed, tested, and validated as an actual ADA approved type thing the $3900 might not be too out of whack. I don’t know that their picture convinced me that is even close to the mark, but I do know that assisted living equipment that will not get your butt sued off the first time it flips out and hurts someone is not built with just $100 of hobby brackets, rc servos, and a stamp board. The company I work for manufactures (among many other odd things) a fly-by-wire driving system for vehicles so I have some experience around this issue. I am not the perrson assigned to the majority of their products though so it is more like I am sitting next to the person living it. Heh.
did you see these -
tribotix.com/Products/Roboti … sories.htm
same site - products - robotis
is $250 in your price range?
28 kg/cm
go here and get the spec’s - link for manual also here
tribotix.com/Products/Roboti … /DX117.htm
ds\
My theory is just to build a custom one from Lynxmotion. That would probably easier and a lot cheaper.
Good point.
Here’s an idea of what you’d need:
3 Servos (I’d say 645’s or 5645’s)
3 ASB-04
3 ASB-09
1 lexxan or alluminum plate to mount onto
And a bit of rubber padding to put on the ASB-04’s, to give them a non-slip grip.
That would only cost 150 to 200 dollars, total.
hey don’t forget your pressure sensors in the fingertips. 
Here is a three servo gripper I threw together last week.
Just an idea, maybe it could work…
jim, is there any end to what u can do?
I imagined the servos themselves being the “fingers”, but this is much nicer.
