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Subject: 
Re: Gripper and lift arm with single motor
Newsgroups: 
lugnet.robotics
Date: 
Mon, 9 Aug 1999 18:38:57 GMT
Original-From: 
Paul Speed <pspeed@augustschell^NoMoreSpam^.com>
Viewed: 
908 times
  
Hello,

Ok, I haven't actually done this but I have given it some
thought.

First, imagine that you just want to lift the arm.  A classic
way would be to put a gear into the pivot point that was fixed to the
arm.  Another gear in the platform could turn this gear to make it go
up and down.

Now, imagine that instead of being fixed to the arm that the
gear in the pivot is free to move.  Connect it to drive the gripper.

So, when the arm is hanging limp then turning the gear will
open and close the gripper.  However, when the gripper is completely
closed, ie: can no longer move, the pivot gear now acts as in the
first example and lifts the arm.

Hopefully, this will be enough of a hint.
-Paul (pspeed@progeeks.com, http://www.progeeks.com/)


David Walton wrote:

I hope someone can help me with this

I tried most of the weekend to try and build a mechanism to grab an item
(49.6x28 VR wheel) and lift it using one new type motor (the ones in the
RIS). All my attempts seem to either self destruct or just didn't work.

Basically my designs were based upon fixing an axle at the lift pivot point
and using a pair of bevel gears to produce rotation to drive a gripper.

What I would like to be able to do is drive the jaw once it is closed the
lift mechanism would engage. I just couldn't get it right and its getting
me a bit frustrated.

NO I can't just use another motor and some touch sensors, I need the motors
for drive adder/subtractor based tracked vehicle and the sensor inputs for
navigation and object detection

Anybody give me any pointers to designs on the web which actually work - I
know Ben Willamson had a design but that doesn't give enough movement of
the gripper jaws for my project

TIA

David Walton

Email: d.walton@ndirect.co.uk

Take a look at my homepage (still under construction though)
http://www.walton.ndirect.co.uk/

Now on ICQ: 44277445

"If it  ain't broke don't fix it !!"
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics



Message has 1 Reply:
  Re: Gripper and lift arm with single motor
 
(...) I have built a one-motor, grasp-then-lift arm as part of my (incomplete) solution to Joel Shafer's soda can challenge. I will try to post some pictures of it soon. The idea is based on the "directional transmission" idea that I first saw at (...) (25 years ago, 9-Aug-99, to lugnet.robotics)

Message is in Reply To:
  Gripper and lift arm with single motor
 
I hope someone can help me with this I tried most of the weekend to try and build a mechanism to grab an item (49.6x28 VR wheel) and lift it using one new type motor (the ones in the RIS). All my attempts seem to either self destruct or just didn't (...) (25 years ago, 9-Aug-99, to lugnet.robotics)

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