PR2 Lite

What Is PR2 Lite?
PR2 Lite a home-brewed robot that is meant to have all the capabilities of PR2 from Willow Garage.  We wanted to create a robot that could be used like the PR2, but not cost $400,000 — the price of a PR2.  We use ultra low cost components such as the $150 Kinect, the low-cost lidar used by the Neato robotic vacuum cleaner, servos with feedback such as AX12+ servos.  ROS (Robot Operating System) provides most of the intelligence.  I am part of a team composed of 4 high school roboticists and their mentor fathers.

The first prototype of PR2 Lite called PR Lite was featured in the front page article December 2011 issue of Servo Magazine!

We also have a second article in the August 2013 issue of SERVO Magazine, which I co-authored.  This article deals with PR2Lite rather than PRLite.

PR2 Lite at Robogames 2012 – Photos taken by Tim Craig

Comparison with PR2:
As shown in the table below, the capabilities of PR Lite are analogous to those of PR2, but are lower quality.

PR Lite PR2
head camera Kinect (2 cameras with LED texture projector for 3D vision) 3 cameras with LED texture projector for 3D vision
base lidar Neato Hokuyo UTM-30LX
tilting lidar Hokuyo URG-04LX-UG01 Hokuyo UTM-30LX
arm DOF 6 (shoulder pan & tilt, elbow pan & tilt, wrist flex & rotate, right and left fingers) 7 (includes forearm and upper arm roll)
arm payload 2.5 lbs 4 lbs
number of arms 2 2
drive system forward with differential steering; spin in place; sideways with differential steering holonomic
torso 12″ telescopic 12.3″ telescopic
computer i7 quad-core with hyper-threading, 6 GB memory, 60 GB solid state drive two i7 quad-core, 24 GB memory, 2 TB disk space (all 2x)
network 8 USB ports, I²C EtherCAT
batteries five 12v Lead-Acid; 30 min runtime Lion; 2 hour runtime
software ROS ROS
joystick control yes yes
wireless yes yes
IMU Sparkfun 6 DOF* Microstrain 3DM-GX2
arm cameras webcam* Ethernet camera

* part currently not installed on robot

RoboGames 2011 demo:
This is a previous prototype of PR2 Lite called PR Lite.

Our PR Lite prototype was demoed at RoboGames 2011, occupying the booth next to Willow Garage and PR2! Our demo featured PR Lite’s arms mimicking a person’s arms. A Kinect used the OpenNI library to find the subject’s skeleton. This skeleton was transformed into spherical coordinates (with a radius), and inverse kinematics were used to position PR Lite’s arms. The arms were made from the Bioloid comprehensive kit constructed to be similar to two Crustcrawler arms. ROS packages from the University of Arizona were then used to control the arms.

Contributors:
Matthew Downing (that’s me!): prototype construction, CAD modeling
Andrew Downing: navigation, high-level wheel controller;  his website here
Nathaniel Lewis: arms, Kinect
Robert Ou: low-level wheel controller, firmware;  his blog here
Alan Downing, Frank Ou, and Michael Lewis (fathers): mentors and miscellaneous
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