Cascade MIMO P-PID Controllers Applied in an Over-actuated Quadrotor Tilt-Rotor

Abstract

To map the Virtual Control Actions (VCAs) into Real Control Actions (RCAs), over-actuated systems typically require nonlinear control allocation methods. On embedded robotic platforms, computational efforts are not always available. With this in mind, this work presents the design of a Quadrotor Tilt-Rotor (QTR) through a new concept of control allocation with uncoupled RCAs, where a nonlinear system is divided into partially dependent and linear subsystems with fast and robust convergence. The RCAs are divided into smaller and linearized sets and solved sequentially. Then, the cascade Multipe-Input-Multipe-Output (MIMO) Proportional (P)-Proportional, Integral and Derivative (PID) controllers tuning were presented with saturation constants and successive loop closure technique, where some open-field environment tests were conducted to validate the respective tuning. In the end, it showed to be reliable, robust, efficient, and applicable when VCAs are overlapped between the subsystems.