THINKING THROUGH DRAWING: PRACTICE INTO KNOWLEDGE

THINKING THROUGH DRAWING: PRACTICE INTO KNOWLEDGE 105

Patrick Tresset and Frederic Fol Leymarie

large scale drawings. This early robot was perform-
ing live notably at Documenta 6, 1977, Kassel in
Germany. From Cohen’s descriptions we can recog-
nize that the performative quality of the installation
had a strong impact on the audience; an effect that
later Cohen would judge distracting. In contradis-
tinction, we are interested in understanding what
aspects of an artistic creative performance may
elicit emotions of the audience or sitter, as this rep-
resents yet another aspect of the full understanding
of the perception of art.

Paul’s technical description
Paul’s Hardware
Paul is a robotic hand-eye system dedicated to
the drawing activity and conceived to be used as a
performer in gallery installations (see fig.2).
Traditionally RC servos have been used as
actuators in DIY robotics and low cost research
projects, but they present numerous drawbacks,
such as not providing any feedback, or the need to
have one dedicated wire for each servo. An interest-
ing alternative are smart servos such as the Dyna-
mixel AX-12 Servos manufactured by Robotis.^3
Each such servo includes an integrated 8 bit micro
controller. The servos are addressed with an 8 bit
ID that can be networked in a daisy chain. Com-
mands are sent by writing some values in registers.
Servos states (for feedback) are queried by reading
values from registers. Commands include velocity,
position, compliance, maximum load. Feedback
includes position, velocity, load, voltage. Even if the
specifications of these servos are rather impressive,
they remain low cost actuators. As such they pres-
ent some other drawbacks including a relatively low
resolution and low feedback frequency. Further-
more the associated construction kits are very well

designed. For these reasons we have opted for these

servos for Paul’s construction.

Paul’s Software

Contemporary robotic software architecture

is based on communication between concur-

rent distributed processes. In recent years we have

seen the development of open source robotic

software frameworks such as ROS4 and YARP5.

These frameworks help organize communication

between sensors, processors, and actuators. One

of the advantages of these frameworks is that they

facilitate the components’ reuse and have a large

ecosystem of research teams that use these and

Figure 2. Arm and Eye

J1: Shoulder

J2: Elbow

J3: Wrist

J4: Hand

L1: Upper arm: 108mm.

L2: Lower arm: 88mm.

L2: Hand + pen: 110mm.

Figure 3. Paul’s architecture overview