because your code will eventually have
a bug, and the robot might damage
itself or the things around it.
Maxwell's arm consists of a five
degree of freedom (DOF) manipulator
with a two-servo gripper. The arm
and gripper use four Dynamixel
MX- 64 servos and three AX- 12 servos.
The lowest four joints of the arm are
MX-64s for extra strength. A lower
cost AX- 12 is used for the wrist
rotation joint, and for both of the
fingers on the gripper.
While a five DOF arm is not
capable of as many varied grasps as a
seven DOF arm (as found on the PR2),
it is quite a bit less expensive to build
since the arm itself weighs much less,
and you have several fewer joints.
The most recent addition to the
arm is the linear actuator which allows
it to move up and down about 20".
This allows Maxwell to reach things
located on the floor, as well as greatly
improving the overall workspace of
what the gripper can reach. The linear
actuator was purchased from Firgelli
Automation, and has a speed of
about 2"/sec. Unfortunately, it lacked
any sort of positional feedback and
I had to hack on an optical encoder.
I hope to eventually replace the linear
actuator with something more
compact and quieter when in
This article laid out the
mechanical and electrical design, and
evolution of my robot, Maxwell. Next
month, we will delve into the software
used to control Maxwell. While
building Maxwell, I documented many
of the smaller iterations on my blog
which can be found at http://show
Discuss this article in the
SERVO Magazine forums at
Need high-quality audio in
a miniature package? The
A8520 Anaren Integrated
Radio (AIR) module offers:
> Uncompressed wireless
digital audio/full CD quality
( 44.1/48KHz/16 bits)
> Robust RF protocol – with
virtually no RF engineering
> Tiny 11 x 19 x 2.5mm
> Integral antenna
FCC, IC, ETSI (pending)
To learn more, write AIR@
anaren.com, visit www.anaren.
com/air, or scan the QR code
with your smart phone.
In Europe, call +44-2392-232392
SERVO 05.2012 51