Moving on from our previous efforts to put the whole structure of the exoskeleton together, we changed the rings that were used to secure the ring to the fingers, which were previously too weak to hold the parts down and allow them to function well.
Improved ring design #1: Using Velcro
Figure 1: Velcro Ring Design
Pros: Strong enough to hold ring down
Cons: Unable to secure the rings on just via snapping the rings in
Improved ring design #2: Using neodymium magnets
Figure 2: Magnet Ring Design
Pros: The rings can be secured just by snapping the ring into the finger since the magnets can automatically attach.
Cons: It may snap to neighbouring magnets as well. Sometimes, the ring would not snap shut for a secure grip.
Improved ring design #3: Using steel to make rings that are of the same shape as our initial silicon ring design
Figure 3: Finger piece with Steel Ring Design
Pros: The steel can expand slightly to allow the finger to enter, but is also able to keep is shape after being snapped onto the fingers.
Cons: May be uncomfortable to squeeze in, necessary to coat the edges with something soft. At the prototype stage, we used a hot glue gun to coat the edges but it comes off after a few uses. This will be an area of improvement.
We decided to go ahead with the steel ring design to secure our finger parts down! Initially, we tried using one ring to hold down the entire part, gluing the ring down to the back portion of the proximal finger piece. This was to ensure that the ring would be in the middle of our proximal phalanges. However, we realised that the single point of attachment would not hold down the front part of the finger piece well enough, and decided to add another point of attachment on the proximal finger piece. If this is confusing, Figure 5 shows the palm view of the rings, and shows how the additional ring provides a better grip on the fingers!
Figure 5: Palm view of the ring attachments