This paper proposes a Negative-buoyancy Quad Tilt-rotor Autonomous Underwater Vehicle (NQTAUV). for which an attitude-tracking controller is designed for the hover and transition modes based on a disturbance-rejection control scheme. First. the structure of NQTAUV is illustrated. https://www.ivoryjinelle.com/amazing-offer-Ohio-University-Ohio-Bobcats-iPhone-13-Pro-Max-Impact-Case-p22134-limited-grab/