• To have robust onboard sensory/computation.
From this set of requirements, I developed a fairly
straightforward base and torso, since I generally prefer to
be writing software rather than debugging hardware or
People often ask me "Which version of Maxwell is
this?" The truth is, Maxwell has slowly evolved over the
past year and a half, and has undergone a number of
revisions. The original build of Maxwell occurred in January
2011, with some minor updates over the following month.
The version shown in Figure 2 used a mix of AX- 12 and
RX- 64 servos, and had no vertical movement for the arm.
In late 2011, Maxwell got a new head, replacing the
large Microsoft Kinect with a much smaller Asus Xtion
sensor. This greatly improved the performance of the neck
servos. At this time, I also added a vertical linear actuator
for the arm so that it could reach the floor, as well as
tabletops. Unfortunately, the portability was sacrificed
because Maxwell no longer fits in his handy pelican case
for transport (at some point, I hope to remedy that). In
early 2012, I upgraded the RX- 64 servos to new MX- 64
servos which have a much higher resolution encoder, as
well as being designed for my 12V power system, which
also allows me to use a single bus for all the servos.
Maxwell, as he stands today, is shown in Figure 1.
The entire robot was designed in Autodesk Inventor,
allowing parts to quickly be exported for laser cutting, and
avoiding costly revisions that might have been caused by
parts not fitting together. Figure 3 shows the robot as
rendered in Inventor.
The mobile base is fairly simple but very robust. It has a
16" x 16" footprint and is constructed of mostly 3/16" thick
Frame materials Laser-cut ABS, mostly 1/8" and 3/16" 1"x1" 8020 aluminum framing
( 2) Zagros Robotics REXC motors
( 2) 4-7/8" BaneBots wheels and hubs
(1) 3" caster
Arm ( 4) MX- 64 servos; (1) AX- 12 servo (1) 20" linear actuator
Gripper ( 2) AX- 12 servos; Bioloid brackets for fingers
Battery 12V sealed lead-acid, 8 Ah
(1) Head-mounted ASUS Xtion Pro Live
(similar to Microsoft Kinect) mounted on
a pan-tilt neck.
FIGURE 2. Maxwell,
circa March 2011.
FIGURE 3. Maxwell
as designed in
SERVO 05.2012 49