GEERHEAD
A student from Hiram Johnson High School is testing code for
the minesweeper Mobot configuration.
Replacing the
batteries in a
minesweeper
configuration.
The platform supports Windows XP, Vista, and
Windows 7, and also the Mac OS X, a Graphical User
Interface (GUI) robot controller, and a C/C++ interpreter
channel for processing and motion control.
“The Mobots are useful in teaching pre-algebra, algebra
I, geometry, physics, physical science, computer science,
and really anything where abstract concepts can be
realized in the physical world to create a greater
understanding for students,” according to UC Davis. Each
unit is individually useful since there is no minimum
assembly/setup that needs to occur to get started in the
classroom.
Engineering Professor
Harry H. Cheng of UC
Davis with one of his
Mobot modules.
Engineering the Mobot's Wheels
— a Lesson in Design vs. Cost
The engineers at Borabo Robotics decided the Mobots
needed their own special wheel accessory to make the
robots mobile. The eventual design included rounded
edges, cut-outs, and extrusions to make sure the wheels
had good tread and traction, and remained in contact
with surfaces in a way that enabled the robots to continue
to be locomotive — even when the module’s joints were
bent at an angle.
One approach the engineers considered
was a two-sided shell design with dead space
inside which could be plastic injection molded
with snap connection joints to connect it to
the Mobot’s rotating interfaces. However, the
Borabo design engineers found the injection
molding approach challenging since the molds
required to create the snap-on features were
pricey. Even a less expensive bump-off process
that adds the overhang features during
removal from the mold could not be applied
to the entire wheel, so another approach had
to be found.
A single-sided design approach was then
considered. This led to several iterations
including a treaded wheel with a central rib,
enabling even rolling. The design could be
easily molded in an inexpensive fashion with
no overhang or special procedures. Still, the
engineers had to reduce the width of the
wheel in an attempt to come in under
budget. This helped but was not enough.
14 SERVO 01.2013