I had created many drafts and sketches to make the system work. One of the methods I had considered was using servos, however I didn’t know if I wanted to use the conventional 180 degree servos or use a linear actuated servo. In the first sketch, I outline the two halves of styrene that sandwich my arm. I initially decided to have 3 points of actuation for the opening and closing mechanism as seen in the 3 dotted squares, however after thinking about the footprint a single servo takes up, I decided to have just 2 points of actuation. I knew that whatever mechanism I had, I would need multiple points of effectiveness since the gauntlet is so long
The next sketch shows my first idea that I had in mind: using the servos’ linear actuation to ‘push’ each halves apart. I began to understand after thinking about it that the amount of separation that can be achieved is limited to the length of the servo arm (from the point of rotation to the end of the arm where the actuation is hinged on). So I logically thought that if I wanted a servo to give the most linear ‘push’, I would need to use the longest servo arms that I can use for the separation distance that I wanted. However, since the servo arm must also rotate rotationally, the length of the servo arm will also have to stick out of the gauntlet while going through the opening and closing motions. Therefore, I decided to use 2 servos for each location of actuation to double the separation distance of a single servo. By using the standard servo arm lengths, I can achieve a separation distance that I wanted as well as keeping the mechanism profile to a minimum.
After conceptually understanding the workings of my opening/closing mechanism, I began to research the parts I would need to mechanically make it work. I obviously would need 2 pairs of servos and I decided to get 9 gram size since I’m already familiar with them.
I then had to determine how I would be connecting the servos to each other. I’ve had previous experience using piano wire and linkage stoppers from when I used to make RC Plane (future segment in this blog). So I ended up buying a set of linkage stoppers which enable me to attach piano wire from each servo arm while still allowing rotation of the wire to occur.
On my gauntlet, I roughly located all of the spots I wanted to attach my servos and I marked them. I had too keep in mind that half of the servos will have to mirror the other half. This is important to understand for the coding aspect of this function since the degree of location that the servo uses will be coded. I simply used a blob of hot glue to attach the servos after scuffing up their surface for a bit.
I then attached my servo arms and added my linkage stoppers. These linkage stoppers have a nut at the bottom of the servo arm so I used some locktite to secure it in place. I then cut my piano wire (1mm) into lengths that would be appropriate for the closed position of the servo mechanism. I then tightened the linkage stoppers using the grub screw and secured the piano wire into place. This conluded the mechanical aspect of my mechanism.