corners and a divider in the middle. The designers built in
ample space for components such as batteries and
microcontrollers. From there, they designed the robot to be
able to “bend at the waist” which is between this lower
frame and the upper torso.
To simulate bending at the waist, the team designed
the robot to make a vertical movement of up to six inches
while still supporting the upper torso and mechanics. The
technology used to create the movement was a linear
actuator; specifically a Thompson Electrak Pro Series linear
The team housed the actuator for the waist bending
system in the lower frame using two pieces of aluminum
C4 conducted a fragment from Hungarian Dance #5
by Johannes Brahms.
The C4 robot uses two humanoid robotic arms,
each with three degrees of freedom. The left arm
points to the particular sections of instruments in the
orchestra when it was time for them to take up their
The two arms indicate the beat pattern and tempo.
The robot would raise and lower its left arm and
increase the breadth of the movement of its right arm
to indicate changes in dynamics.
The student roboticists used a software program to
convert a MIDI-based musical score into something the
robot could follow to guide its own movements. The
robot uses a real-time audio processing capability to
listen to the orchestra and respond to its efforts. “If the
orchestra was performing differently than the robot
was conducting, the system sent interrupts to the
microprocessor to change the robotic motion to adjust
the orchestra,” the students said.
The robot’s head was a display with a smiley face
that smiled when the orchestra played well, and took
on a serious or sad face if the orchestra was not
performing at its best.
12 SERVO 10.2010
plating bolted to two pieces of angle iron, secured to the
bottom of the lower frame’s top plate. A bolt running
through both plates beneath the actuator holds it in place.
The team covered the non-moving areas of the actuator
with noise canceling foam to keep sound from spreading
and reverberating in the auditorium.
The robot’s facial expressions consist of six images
taken from the Bosphorus 3D Face Database and display on
the monitor to indicate emotional changes. The team
altered the images for brightness, background consistency
(black), and facial consistency (no blemishes) so the
orchestra could clearly understand and interpret the facial
The robot learned the conducting movements by
analyzing a video sequence of one of the students
conducting the same piece of music. A video tracking
system previously developed by Dr. Salgian's students was
used to extract the locations of the conductor's hands.
From here, the students were able to compute the required
joint locations using inverse kinematics.
This robot — a comparable three degrees of freedom
two arm robot — is half human size and was built using the
VEX robotics kit. It is also controlled by the Arduino
Two-dimensional cartoon faces represent the robot’s
facial expressions. The team selected cartoon faces for their
simplicity, familiarity and because they would not seem too
human for a robot, thus avoiding the uncanny valley
phenomenon ( www.popularmechanics.com/technology
The team covered the arms and body with yellow and
gray foam to beef up the body and ensure its visibility.
Instead of video analysis, this robot used annotated
MIDI files and a set of standard conducting gestures to
learn how to conduct a given musical piece.
C4 is the only one of the three robots that can get
feedback from the orchestra. It uses ChucK — an audio
programming language for real-time performance and
analysis — to verify if the dynamics and tempo of the music
played by the orchestra matches the one conducted.
This conducting robot is decidedly non-human. A
square, black board with a rotating baton in the center and
four consecutively lighting LEDs that move away from and
back to the center of the board comprise this bot.
The robot employs two motors and a circuit board to
actuate the baton and lights. The board is a BASIC Stamp.
A bicycle hub and lever attached to one of the motors
actuates the four levers attached to the LED lights.
The motors are a Parallax standard servo and a