Page 381 - Robot Builder's Bonanza

350 EXPERIMENTING WITH ROBOTIC ARMS

Build a Robotic Arm from a Kit

The revolute coordinate arm described in the preceding section is designed around simple
components that can be constructed using ordinary tools and limited precision. If you want
something more elaborate but don’t want to build it from scratch, you can choose from
among a number of specialty robotic arm kits or use custom construction set parts

ARMS FROM ROBOTICS CONSTRUCTION SET PARTS
Think of these as Erector Sets for grown- ups— they’re parts of various shapes and sizes, with
holes already drilled in them for attaching to R/C servos, motors, and other robotic compo-
nents. One popular robotics construction set, the TETRIX Robotic Design System from online
educational outlet Pitsco. Several sets are available, each with a different assortment of parts.
You can also purchase individual parts as needed. Most construction sets are made with
stamped aluminum, though they may also contain plastic pieces.
Even with the variety of parts that come in the typical robotics construction set, you’re not
limited to using just those components. Unless there’s a restriction otherwise (you’re building
a robot for a school competition, for example), you should feel free to add your own bits and
pieces.
For example, you can combine a TETRIX U- channel with your own homebrew servo
mounts to make two of the joints (shoulder, elbow) of a robot arm. The TETRIX U- channels
measure 1- 1/4″ in each of the three faces and are available in different lengths. I’ve used the
160mm (about 6- 1/4″) channel in the upper arm mechanism shown in Figure 28- 12.

ARMS FROM SPECIALTY KITS
Thanks to the popularity of amateur and educational robotics, there are plenty of specialty kits
that are constructed just for the purpose of building a robot arm. Some are low- cost and
meant for casual experimentation using manual switch control, but others, like the arm in
Figure 28- 13 from Lynxmotion, use R/C servo motors and microcontrollers to precisely posi-

Figure 28- 12 Two servo motors, with homebrew
mounts, attached to a TETRIX U- channel beam. Use a
combination of ready- made and home- built parts for Figure 28- 13 Robot arm kit, shown with control
constructing arm arms. electronics and gripper. (Photo courtesy Lynxmotion.)

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