Page 304 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

robotic arm operate as described before, but in addition, each func-
tion and the time elapsed are recorded into a script file. The script
file can contain up to 99 separate functions, including pauses. The
script file itself can be replayed 99 times. Writing different script
files allows one to experiment with computer-controlled automa-
tion and animatronics. The Windows 95/98 program operation is
described in more detail later on. The Windows program is included
in the robotic arm interface kit or may be downloaded at no cost
from the Internet at http://www.imagesco.com.
In addition to the Windows program, the arm can be operated using
BASIC or QBASIC. A DOS-level program is included on the disks that
come with the interface kit. However, the DOS program only allows
interactive function using the computer keyboard (see BASIC listing
on one of the disks). Script file creation is not available in the DOS-
level program. However, if one knows how to program in BASIC,
the arm may be programmed to perform a sequence of motions
similar to the script files created in the Windows program. The mo-
tion sequence may be repeated, as is done in many animatronics.

Robotic arm
283
The robotic arm (see Fig. 15.1) can move freely in three axes of
motion. The elbow joint can move vertically (up or down) through an
arc of approximately 135 degrees. The shoulder joint moves the grip-
per forward and back through a 120 degree arc. The arm can turn
clockwise (CW) or counterclockwise (CCW) from the base approxi-
mately 350 degrees. The gripper portion of the robotic arm can grasp
and release small objects up to 2" in diameter and finally can rotate
the gripper section approximately 340 degrees at the wrist.

The OWI Robotic Arm Trainer uses five small direct current (DC)
motors to produce motion. The motors provide a “wire” control to
the robotic arm. “Wire control” means that each robotic function
(and hence DC motor) is controlled by a wire (electric power). Each
of the five DC motors controls a robotic arm function. The wire con-
trol makes it possible to build a controller unit for the arm that will
respond to electrical signals. This simplifies the task of interfacing
the robotic arm to a PC printer port.
The arm is made from lightweight plastic. Most of the stress-bearing
parts are also made of plastic. The DC motors used in the robotic
arm are small, high revolutions per minute (rpm), low-torque
motors. To increase the motor’s torque, each motor is connected
to a gearbox. The motor-gearbox assemblies are used inside the

Team LRN
Robotic arm and IBM PC interface and speech control