Modeling and Control of an Aerial Manipulator with a Gravity Center Adjusting Mechanism

To eliminate the gravity center deviation of the aerial manipulator in grasping and transporting tasks, an aerial manipulator with a gravity center adjusting mechanism is designed and a control strategy for adjusting the gravity center is proposed. The strategy dynamically calculates the offset of gravity center of the combined system when the robotic arm moving by kinematic derivation of the robotic arm in manipulation system, and rotates the adjusting mechanism by the angles calculated according to the moment equilibrium equations to adjust the gravity center of the combined system. In order to validate the effectiveness of the proposed control strategy, simulations are performed in Matlab environment to study the influence of the robotic arm movement on the curve of gravity center of the combined system and the hovering pose with and without the gravity center adjusting control. Outdoor flights are performed to test the effectiveness of the adjusting mechanism for stabilizing the system when hovering with the payload. Experimental results demonstrate that the gravity center adjusting mechanism can adjust the offset of gravity center in real time when the aerial manipulator performs tasks with the proposed control strategy, and the effectiveness of the control strategy is validated.