Up — and So
Do Its Makers
by Alan Downing, Matthew Downing, and Frank Ou
You can discuss this topic at
PRLite was first featured on the cover of the
December 2011 SERVO Magazine (Figure 1). In
that article, we described how four high school
students and their mentor fathers prototyped their
own PR2. PRLite had its own tilting LiDAR, a Kinect,
a 12" torso lift, two Bioloid arms, a Neato LiDAR on
its base, four partially pivoting Parallax motors and
wheels, and more. However, PRLite had a short
wooden frame with arms positioned at the bottom
of the front torso. It didn't look much like Willow
Much has changed over the last two years. First, three of the builders are now in universities and make only occasional appearances at our weekend meetings.
Similarly, our robot has grown up to look and act more like a
PR2. Now made of machine-cut PVC, PR2Lite is between 40”
and 52” high at the shoulders, and has LiDARs and a Kinect
placed similarly to their PR2 counterparts. Plus, PR2Lite sports
new upper arms powered by linear actuators, a new CHR-UM6
IMU, and a lot of new ROS-compatible software.
Our PR2Lite team now mostly consists of Alan (software),
Frank (hardware, networking, firmware), and Matthew (builder,
designer, high school robot club president-elect). Figure 2
contrasts the old wooden prototype with the revised PR2Lite.
Design of the Body
Matthew designed and built PR2Lite’s body. He used
Autodesk Inventor to model the pieces which were then
machine-cut from quarter and half inch PVC by Mr. Plastics in
Oakland, CA. Like PR2, our robot is the appropriate height to
manipulate objects on tables and do other human interactions.
The Autodesk Inventor screenshots show the design of the arms
and upper torso when lowered and raised (Figure 3).
The upper arms are lifted by 4” linear actuators and rotated
at the shoulders by two AX- 12 servos. The linear actuators are
34 SERVO 08.2013