Publication
Prioritized Motion Control Robust to Actuator Failure for Hovering-Type AUVs Using INDI-QP
Tom Vincent Slawik; Shubham Vyas; Bilal Wehbe; Leif Christensen; Frank Kirchner
In: IEEE Robotics and Automation Letters (RA-L), Vol. 11, No. 9, Pages 10481-10488, IEEE, 7/2026.
Abstract
INDI-QP extends Incremental Nonlinear Dynamic Inversion (INDI) with a quadratic program to prioritize critical degrees of freedom during actuator failure. While the algorithm has gained significant attention within the aerial vehicle community, it has not yet been studied for underwater systems. In this work, we adapt INDI-QP for the 6-DOF autonomous underwater vehicle ``Cuttlefish'', which is equipped with eight thrusters and evaluate it on a 360-degree inspection trajectory. To generate the inspection motion, a circular motion controller maintains a constant radius and attitude relative to a fixed object while keeping the line of sight aligned with the sensor axis. Our experiments show that, by prioritizing critical degrees of freedom, the proposed INDI-QP controller safely executes the inspection trajectory and maintains a significantly smaller line-of-sight off-axis error than a non-prioritized INDI baseline, even with fewer than six functional thrusters, at the cost of increased positional tracking error. Passive fault-tolerant control is enabled without thruster speed measurements by integrating a parallel thruster model into the control architecture.