Tell A Friend

  • Friend's email:
 

Self-moving robotic arm
This is an attempt to construct robotic arm according to the current challenge. Construction of claws and the chassis are taken from my previous 'bottle grabber'

My goal was to create arm similar to human one, that can catch things from the top. That means one wrist with 1DoF, one shoulder with 2DoF (up/down and left/right) and claws (1DoF - open/close). If I count right it is 4DoF.

Using tracked chasis with independent control of each tack allowed me turn whole device left/right at the place, while still having possibility of moving whole device forward/backward. It seems I've got yeat another DoF here (fwd/back) - so 5 in total :).

chassis is powered by two simple motors, NOT the XXL. As they are relatively weak, I had to add a set of gears to increase torque. Now it is sufficient to move and turn whole arm. Motors are RC controlled with Lego Buldozer IR set. I want to make them controlled by NXT brick with IR Link sensor, unfortunately (I must complain at this place) Lego company is discriminating customers in Slovakia by not shiping items from ishop to Slovakia and also, by not supplying non-common items to resellers in Slovakia (yes, I have official letter from Lego to one of the resellers). I feel handicaped in this challenge. Anyway. For now it is operating in demo mode with motion controlled temporary out of NXT, I hope Lego will reevaluate their business policy soon and I will be able to buy IR link sensor.

Elbows of the arm are powered by NXT motors. I tried to move as much mass out of the arm as possible (claw motor is on the chassis for example), however the arm is still very heavy. I had to use really big set of gears to increase torque of NXT motor to be able to rise such heavy arm. Another challenge was the move of the wrist, that has big angle of freedom - the solution is obvious from pictures and video.

Control program is very simple - it only provides functions to test elbows. I will create more complex one with some level of authonomy when getting IR link sensor.
Program reads status of touch sensors and controls the elbows based on that (one sensor to elbow, the second one to wrist). Long press means 'move until pressed', short press means 'change direction of the next move'.
Claws are controlled by NXT buttons.

Posted by:

 Martin9912

Created:

 10 February 2010

Rate:

 

Tags:(?):

 roboticarm, video

Comments

3 comments

  • legosteen8000

  • Dont worry about the ir link sensor, i think you can put now some other sensors on it like the coler sensor to identify the object that the claw let fall when the coler isnt right, and let it hold if coler is right.

  • Posted 1189 days and 23 hours ago



  • lijap5

  • Amazing, I am working on my entry now too. :)

  • Posted 1185 days and 17 hours ago


Add A Comment


Please log in or register to add a comment