Attitude control of a swashplate-less rotorcraft based on DI (Formula presented) -synthesis: Parameter identification and experimental validation

Rotary-wing aircraft possess vertical take-off and landing (VTOL) and hovering capabilities, enabling high-resolution exploration of complex Martian terrains such as cliffs and caves. The directly coil-actuated rotorcraft, as a swashplate-less configuration, simplifies the control mechanism and enhances response speed. However, in coil-driven cyclic pitch control, the response of blade pitch angle exhibits amplitude attenuation and phase lag relative to the desired cyclic pitch input. Meanwhile, deviations in calculating the blade pitch angle using magnetic induction intensity lead to errors in the cyclic pitch response. In addition, inflow interference between coaxial rotors and blade flapping dynamics introduce coupled disturbances to attitude control moments. To address these challenges, this paper employs frequency-sweep identification to obtain the actuator dynamic model and identify the rotorcraft dynamics parameters and uncertainty bounds. A composite attitude controller combining dynamic inversion (DI) and μ[jls-end-space/]-synthesis is then implemented: the inner loop employs dynamic inversion, based on feedback-linearization principles, to achieve system decoupling, while the outer loop adopts μ[jls-end-space/]-synthesis to ensure robust stability and performance under structured uncertainties. Experimental results demonstrate that, compared with standalone PI state-feedback control and μ[jls-end-space/]-synthesis control, the proposed composite controller achieves shorter rising time, higher steady-state tracking accuracy, and stronger suppression of coupling-induced disturbances.