Purpose
This paper aims to investigate the distributed formation control problem for a multi-quadrotor unmanned aerial vehicle system without linear velocity feedbacks.
Design/methodology/approach
A nonlinear controller is proposed based on the orthogonal group SE(3) to obviate singularities and ambiguities of the traditional parameterized attitude representations. A cascade structure is applied in the distributed controller design. The inner loop is responsible for attitude control, and the outer loop is responsible for translational dynamics. To ensure a linear-velocity-free characteristic, some auxiliary variables are introduced to construct virtual signals in distributed controller design. The stability analysis of the proposed distributed control method by the Lyapunov function is provided as well.
Findings
A group of four quadrotors with constant reference linear velocity and a group of six quadrotors with varying reference linear velocity are adopted to verify the effectiveness of the proposed strategy.
Originality/value
This is a new innovation for multi-robot formation control method to improve assembly automation.
In this paper, a formation control method of quadrotor Unmanned Aerial Vehicles (UAVs) by vision-based positioning is presented. The relative positions and attitudes of two UAVs with respect to a visual marker attached to the third UAV is estimated by a camera calibration method. Based on the estimated positions and attitudes, two UAVs are controlled to the desired positions to form a given formation with respect to the third UAV. A simplified dynamics model of a quadrotor UAV is utilized to design a controller. The proposed formation control method is validated by an experiment with a motion capture system which provides the ground truth of the position data.