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Author Topic: Shoulder Joint: 2 degrees of freedom  (Read 1080 times)

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Offline 40coaplinTopic starter

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Shoulder Joint: 2 degrees of freedom
« on: January 25, 2013, 09:40:01 AM »
I'm designing a robot with three degrees of freedom in the arm, one in the elbow and two in the shoulder. However, I need help conceptualizing an idea for how to orient the motors and design the "joint" In the shoulder I need movement along the sagittal and transverse planes.

I was thinking of using a ball shaped joint with one motor physically attached to the side of the sphere, with the other motor inside the sphere having a part attached to it so that it may move side to side along a path cut into the sphere.

If anyone has any ideas they can communicate I would be very happy to hear them.

Thank you
« Last Edit: January 25, 2013, 09:41:25 AM by 40coaplin »

Offline jwatte

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Re: Shoulder Joint: 2 degrees of freedom
« Reply #1 on: January 25, 2013, 12:38:39 PM »
If you want to drive a universal joint in two degrees of freedom, the typical way to do it is to extend the "+" in the universal joint, and couple them to the horn of a servo. The servo rotating will then push one end and pull the other end of the plus, and it will move. You can mount one servo on each link connecting to the plus.

Note that using a ball joint for a 2-dof arm is less robust than using a universal joint, because you will get torque on the joint which will have to be absorbed only by the control assembly, in directions it is not designed to be strong.

 


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