US Patent 10569430 Low variability robot

An apparatus including a frame, a first position sensor, a drive and a chamber. The frame has at least three members including at least two links forming a movable arm and an end effector. The end effector and the links are connected by movable joints. The end effector is configured to support a substrate thereon. The first position sensor is on the frame proximate a first one of the joints. The first position sensor is configured to sense a position of two of the members relative to each other. The drive is connected to the frame. The drive is configured to move the movable arm. The frame is located in the chamber, and the drive extends through a wall in the chamber.