We consider a helicopter structure that comprises a double blade coaxial shaft rotor and swash masses to control the orientation and therefore maneuvering the vehicle. It is referred to as a swash mass helicopter (SMH). The SMH is subject to disturbances so that the problem addressed in this paper is the robust control under the presence of matched and unknown disturbances. We first present the dynamical system of the SMH. Then, under the presence of highly-coupled inputs, an interconnection and damping assignment passivity-based Control (IDA-PBC) mechanism is derived. The problem of increasing robustness in the presence of disturbances is addressed. Finally, several numerical results are reported to show the performance of the proposed control design.
