Analysis of Independent Control in Tilt-Rotor Quadrotors

The underactuation of conventional aerial vehicles limits their ability to independently control position and attitude, motivating the use of overactuated designs such as tilt-rotor quadrotors. Existing works on tilt-rotor quadrotors primar- ily focus on determining the minimum thrust-to-weight ratio required for hovering at arbitrary orientations. However, they do not address the maximum allowable attitude range within which independent control is feasible given specific thrust constraints. In this work, we investigate the feasible attitude range within which a tilt-rotor quadrotor can maintain independent control, given rotor thrust limits. First, we formulate the thrust constraints as convex functions and solve them using convex optimization techniques to identify feasible sets. To determine the maximum attitude that allows for independent control under thrust con- straints, we pose a nonconvex optimization problem and employ a successive convex approximation (SCA) technique to compute a optimal solution, which corresponds to the optimal solution of the original nonconvex problem. Given the maximum attitude limits, we then compute the minimum thrust required per rotor to achieve independent control. Furthermore, we determine the maximum allowable disturbance magnitude that the tilt-rotor quadrotor can handle while retaining independent control. The study results are verified through processor-in-the-loop (PIL) simulations and outdoor hardware experiments on a tilt-rotor quadrotor. An illustrative video showing both the PIL simulation and hardware experimental results can be found at: https:// youtu.be/6qjc9_KtACM Note to Practitioners—This paper is motivated by the potential application of tilt-quadrotors in inspection, search and rescue, and aerial manipulation, owing to their ability to perform agile maneuvers in confined environments. However, ensuring independent control of both position and attitude across all orientations remains a practical challenge, primarily due to limitations in rotor thrust capabilities. This work presents a practical framework to determine the range of attitudes over which independent control can be maintained, based on the available thrust from each rotor. Using convex optimization techniques, the proposed method evaluates whether the thrust capacity of the vehicle is sufficient for the desired operational envelope. If not, it also identifies the minimum thrust required per rotor to enable full-range control. Additionally, the framework assesses the maximum disturbance magnitude the system can tolerate while retaining independent control. The findings are Received 24 April 2025; revised 15 September 2025 and 10 Novem- ber 2025; accepted 9 December 2025. Date of publication 15 December 2025; date of current version 12 January 2026. This article was rec- ommended for publication by Associate Editor R. Carli and Editor M. Dotoli upon evaluation of the reviewers’ comments. (Corresponding author: Sathyanarayanan Seshasayanan.) Sathyanarayanan Seshasayanan is with the Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, 971 87 Luleå, Sweden (e-mail: satses@associated.ltu.se). Sanjay Chaturvedi and Soumya Ranjan Sahoo are with the Electrical Engineering Department, Indian Institute of Technology Kanpur, Kanpur 208016, India (e-mail: sanjayc@iitk.ac.in; srsahoo@iitk.ac.in). Digital Object Identifier 10.1109/TASE.2025.3644498 validated through simulations and outdoor experiments on a custom-built tilt-rotor quadrotor platform, offering actionable insights for system design and mission planning.