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338 BUILD ROBOTS WITH LEGS

Figure 27- 24 Completed Hex12Bot,
a hexapod robot with six individually
manipulated legs. Each leg uses two servos,
and therefore has 2 DOF.

the servo to the horn on the solid plate. See the section “Build a 12- Servo Hexapod” later in
this chapter that uses these joints for legs.

USING AS A SENSOR TURRET

Turrets use motors to scan a sensor, or a group of sensors, back and forth. A single turret
made with a standard R/C servo can provide near- 180° coverage, sweeping back and forth
looking for objects nearby and far. An X- Y joint allows you to sweep the sensor(s) horizontally,
as well as tilt up and down. Mount a servo pointing upward on the robot chassis, and attach
it to the horn on the solid plate. This provides the side- to- side motion of the turret.
Then attach a bracket of your own design to the other servo. This provides the up- and- down
tilt motion. Sensors tend to be very lightweight, so they don’t need a heavy- duty turret struc-
ture. That saves on expense and weight.

USING AS PART OF A WRIST

By stringing X and Y segments together you can create a 3- DOF robotic wrist, similar to the
joints of the human wrist and forearm, which can be used with a variety of grippers. See
Chapter 29 for ideas on making robotic grippers.

Bonus Project: Build a 12- Servo Hexapod

Using the X- Y joints described in the previous section you can construct a hexapod with
2- DOF legs. The robot uses 12 servos, 2 per leg. Besides the X- Y joints already discussed, and
the servos (of course), you need only six simple leg pieces and a base to mount everything on.
Figure 27- 24 shows a completed 12- servo hexapod, the Hex12Bot, constructed with six
X- Y joints. The robot measures 11- 1/2″ by 7″, and stands over 6″. Full construction plans,
with cutting and drilling templates, programming examples, and parts lists and sources, is
provided as a free bonus project on the RBB Online Support site.

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