Fuzzy Logic based Variable Damping Admittance Control for Multi-UAV Collaborative Transportation

Abstract

This paper implements a variable damper admittance control in a multi UAV system. Two Unmanned Aerial Vehicles (UAVs) are considered in this work for simplicity, to collaboratively transport a common payload. A leader-follower architecture is used. The leader UAV uses a traditional Proportional, Integral and Derivative (PID) control whereas the follower UAV makes control decision by a force feedback admittance controller. The admittance controller simulates a virtual spring mass damper system to implement a force feedback controller for the follower UAV. It ensures effective force compliance via proper choice of admittance parameters, which are stiffness, mass and damping of a virtual spring mass damper system. However, the performance of the controller can be improved by following a variable damping admittance strategy that allows adaptation of the damping coefficient based on the interaction contact forces and their rates, acting on the follower, due to leaders motion. Calculation of variable damping coefficient is proposed to be carried out using Fuzzy Logic (FL) that utilizes heuristic and intuitive knowledge for calculations. The proposed scheme provides effective performance in comparison to a constant damping admittance scheme, which is validated through the results provided in this paper.