I'm still waiting to receive the strain gauge that will be placed in the middle of fore arm. It will be used to determine if there is any object suspended on the ExoArm.

So far my idea is as following (it's just the idea and may have big flaws, but until I receive the part I can't be sure)

- There is no weight on the ExoArm:

This one is simple. Strain gauge will deflect when my arm is moved up or down, so controlling this movement shouldn't be so hard.

- An object is suspended on the ExoArm:

The strain gauge sensor will detect a mass of the object, therefore we know the force and also torque. Torque changes with the angle (theta) of the object but if we say that the upper arm is parallel to the body, then the Phi angle is the same as -Theta angle.

So now we have a good estimate of the torque. Here is the part where I lose my "insight" into the mechanics. If an object is suspended on the ExoArm when I try to move my arm up, the torque on the ExoArm changes. And if torque changes, the output of strain gauge also changes, therefore the ExoArm will follow your arm depending whether the strain gauge output it bigger or smaller. So this could maybe be an effective way to control the ExoArm. I'm still thinking and trying to come up with a 100% effective way, but at the moment this is as furthest as I am.

Would love to hear your ideas and suggestions!