A comparison between H-infinity/Mu-synthesis control and sliding-mode control for robust control of a small autonomous underwater vehicle

This paper presents a comparison of H_∞/μ-synthesis sliding-mode that was done for heading and depth control of the Draper Laboratory/MIT Sea Grant Sea Squirt autonomous underwater vehicle (AUV). The approximate decoupling of the AUV heading and depth dynamics allowed us to have decoupled heading and depth designs for both the H_∞/μ-synthesis and the sliding-mode methodologies. The H_∞/μ-synthesis based controllers and the sliding-mode based controllers were implemented and tested by using a simulation of the AUV full order nonlinear model (including thruster and sensor dynamics). We analyzed the performance of the controllers (for a simultaneous depth and maneuver) over the approximate range of axial velocities commanded by the AUV. The performance of the controllers in the face of additive sensor noise was also analyzed