Wrist Design

The wrist of the robotic arm has two degrees of freedom and the movement of the gripper, utilizing a total of three servos.  The wrist allows the hand to swing horizontally as well as rotate along the vertical access.  The vertical rotation servo is the first servo in the sequence so that the entire remainder of the wrist, and subsequently the hand, can be rotated allowing for the swing of the gripper to be horizontal, vertical, or anywhere in between.  For ease the swing of the gripper is referred to as horizontal rotation, the direction of swing when the vertical rotation servo is in its default position.

Figure P6.1: Annotated Top View of Gripper

This image displays the set up of the wrist.  Each servo is mounted to a standard servo bracket (S.S.B.).  The gripper servo's S.S.B. is connected to the horizontal rotation servo by a "C" bracket, with a ball bearing at the lower connection point with the S.S.B. of that sevo.  the vertical rotation servo is directly connected to the S.S.B. of the horizontal rotation motor.  The vertical rotation bracket will be connected to the forearm of the robot.

Figure P6.2: Alternative View of Wrist

This image shows how the thumb is mounted to its mounting plate, which fits between the S.S.B. and the "C" bracket that connect the horizontal rotation servo to the gripper servo.  The thumb pertrudes over the servo so as to be closer to the pivot (servo disk) of the two fingered gripper, allowing for tighter closing of the hand.