Underwater Robotics Club (MATE ROV)

I was tasked with helping to designing the arm of an underwater robot that had full rotational and linear motion. 

• Come up with an arm design that can move linearly and rotationally
• Design the arm so that the motors controlling its motion or the opening and closing of the grip's jaws can be stationary
• Ensure that the design will not be too heavy but will be strong enough to lift objects
• Add attachments for the jaws at the end of the grip

• Through numerous meetings the design of the arm was deliberated over and finally a design was settled upon which utilized two sets of rack and pinions, one for rotation and the other for linear motion, each taking up half of the arm's length
• A hole was bored through the center to allow a string through to pull the jaws closed, allowing for the motor winding/unwinding the string to be stationary
• Four supports with pin holes were extruded from the front of the arm for the attachment of the jaws

•  Due to the limited resources of the club, we did not have access to a large 3D printer and the arm could not be printed as one peice
  • We split the arm into two pieces to be printed separately and later attached with a pin
• PLA plastic, which is used in our 3D printers, is not ideal for the design because, while it is light, it is not very strong and not ideal for use in water. Additionally, the rough surface caused by the layering of 3D printing makes it so that the rack and pinion do not slide well
  • We hope to get the funding to machine the arm out of metal
• Attaching the arm to the rest of the robot while still allowing it to slide and rotate is tricky
  • We designed a tube for the arm to fit into with a slot for the linear and rotational gears to interact with the arm

• As of right now, the design has been iteratively tested with the 3D printer and works as intentioned
• The next steps are to finalize the dimensions before hopefully getting the final design machined