The PR2, Personal Robot 2, designed by Willow Garage, is a service robot designed to work with people. As a personal robot, the PR2’s main function is to undertake applications that enable people to be more productive at home, at work and at play. The PR2 combines the mobility to navigate human environments, and the dexterity to grasp and manipulate objects in those environments. The robot arms are back-drivable and current controlled so that the robot is able to manipulate objects in unstructured environments; the arms have a passive spring counterbalance system that ensures they are weightless. The PR2’s wrist has two continuous degrees of freedom and sufficient torque for the robot to manipulate everyday objects. The two-pronged gripper can grasp all kinds of everyday objects. The PR2’s head and neck area has numerous sensors including multiple cameras and a Microsoft Kinect sensor. The PR2’s head can pan 350° and tilt 115°.
The PR2 has two 7-DOF arms with a payload of 1.8 kilograms (4.0 lb). Sensors include a 5-megapixel camera, a tilting laser range finder, and an inertial measurement unit. The “texture projector” projects a pattern on the environment to create 3D information for capture by the cameras. Willow Garage calls this “textured light”, but this approach is better known as structured light. The head-mounted laser scanner measures distance by time-of-flight. The two computers located in the base of the robot are 8-core servers, each of which has 24 Gigabytes of RAM, for a total of 48 GB. The battery system consists of 16 laptop batteries.