  Gesture-based interfaces are often used to achieve a more natural and
intuitive teleoperation of robots. Yet, sometimes, gesture control requires
postures or movements that cause significant fatigue to the user. In a previous
user study, we demonstrated that na\"ive users can control a fixed-wing drone
with torso movements while their arms are spread out. However, this posture
induced significant arm fatigue. In this work, we present a passive arm support
that compensates the arm weight with a mean torque error smaller than 0.005
N/kg for more than 97% of the range of motion used by subjects to fly,
therefore reducing muscular fatigue in the shoulder of on average 58%. In
addition, this arm support is designed to fit users from the body dimension of
the 1st percentile female to the 99th percentile male. The performance analysis
of the arm support is described with a mechanical model and its implementation
is validated with both a mechanical characterization and a user study, which
measures the flight performance, the shoulder muscle activity and the user
acceptance.
