Abstract
This article develops and experimentally tests a supervisory risk
controller used to increase the safety of drone operations. Its task is
to monitor the state of the drone and environment and to use this
information to automatically change safety-critical parameters in
real-time during operation.
A case study of a tethered industrial inspection drone is considered. A
system theoretic process analysis (STPA) is performed to identify how
the system can fail. A Dynamic Decision Network (DDN), used as an online
risk model, is built based on the results of the STPA. An optimization
approach is used to choose an optimal parameter configuration that
ensures an acceptable risk level.
Through experimental tests, it is demonstrated how the supervisory risk
controller is able to identify the state of the drone and the
environment by combining information from multiple measurements over
time and how it chooses values for the maximum speed, safety distance,
and maximum vertical acceleration that produces an acceptable risk
level. The parameters are updated during flight based on the output from
the supervisory risk controller. When no parameter set can ensure an
acceptable risk level then a recommendation of aborting the mission is
sent to the human operator.
Video of the experimental results can be found at
https://youtu.be/RKhG9bguRJY