I'm experimenting with a couple of servo driven grippers for my AR3.
The first is an open source project. It uses a Dynamixel MX-28AR servo and 3D printed parts. https://ieeexplore.ieee.org/document/7109102?arnumber=7109102 https://www.alaris.kz/research/open-source-3d-printed-underactuated-robotic-gripper/
The next is very basic. It also uses a Dynamixel MX-28AR, a couple frame parts from Robotis and 3D printed parts.
I'm using a Dynamixel Shield for Arduino to drive the servos. I'm currently using this with an Arduino Due because the shield takes over the uart, and the second uart of the Due makes debugging the code easier. The Uno might work as well. I'll need to add a 12v source for the shield. https://www.robotis.us/dynamixel-shield/ Programming is fairly straight forward so far. I believe there are other Robotis servos that might be better suited for this application, but this is what I started with from the Alaris project. They are a bit pricey, but they are intellegent devices. I'm currently adding wiring to the AR3 to support these grippers. The AR3 has been such a rewarding project to learn from. I knew nothing about robotics before starting, and this has been a blast! Thanks so much to Chris for making this possible.