Friday, 14 February 2014

Elbow Mod update ver 3

After a some testing I found the version 2 of the elbow mod to be lacking
when power was removed to joint sagged when power was applied the joint would snap into position after a few day trying to control the joint the plastic started to fail. The arm was tearing it self to pieces the solution would be motor breaking and velocity control. Another idea is to use a worm screw gearbox but the original Inmoov gearbox is not suitable but the  Hector   robot has a gearbox that would work with some modification I had some parts laying around from a previous idea
they wern't of good quality and  I didn't have enough filament to reprint or the bearings required so i made some PLA bushes. Not wanting to use a motor and controller I opted for the standard servo with feed back. The good news is it works
and I have nearly 160 degrees of rotation the servo handles the load fine but the feedback is a little jittery later I will change the servo with a motor and the feedback will be solved. the elbow pivot is a little high. I want to do some testing with the complete arm before i reprint the parts. What i really need to know is if the arm can reach and pick up objects for a table. The original hand is very limited
so I replaced the hand with a claw, the arm now has 6 DOF  and a gripper all with feedback and controlled through action servers. Of course that brings in it's own problems as the joints have to get to there goal with a high degree of accuracy before moving on to the next goal.

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