Design and control of deformable quadrotor with varying length arms

Deformable quadrotors can manipulate their specific structure for specialized tasks or excellent flight performance under diverse conditions. With added deformation mechanism, the quadrotor exhibits higher flexibility; however, this is accompanied by difficulties in modeling analysis and controller design, which are crucial issues. Here, a novel deformable quadrotor that can alter its arm’s length is designed by combining the crank-slider mechanism and cross-configuration. The dynamics, including the attitude and position systems, are analyzed and the former is further described as switched linear parameter varying (SLPV) systems from a control-oriented perspective. In addition, a combined SLPV/proportion-integration-differentiation (PID) attitude controller is developed to handle different deformable quadrotor modes, which guarantees the stability of the closed-loop attitude system during the deformation process and achieves attitude tracking. Furthermore, together with the cascade PID position controller, the entire flight controller is constructed whose feasibility is verified via fixed-point hovering and trajectory tracking experiments.