Visual servoing of quadrotor UAVs for slant targets with autonomous object search

Abstract

In this paper, an enhanced visual servoing method is designed for a quadrotor unmanned aerial vehicle (UAV) based on virtual plane image moments, under underactuation and tight coupling constraints of UAV kinematics. Moreover, in order to make the UAV search visual targets autonomously in target vicinity during flight, a flexible flight system is developed with stages of take-off, target searching, and image-based visual servoing (IBVS). With dual-camera sensor configuration, the UAV system searches targets from given directions while making localization. A virtual image plane is constructed and image moments are adopted to decouple UAV lateral movement. For a non-horizonal target, homography is utilized to construct the target plane and transform it into a horizonal plane. Backstepping techniques are used to derive the nonlinear controller to realize the IBVS strategy. Stability analysis proves global asymptotic performance of the closed-loop system. Experimental verification shows feasibility of the overall flight system and effectiveness of the visual servoing controller.

Vision-based UAV adaptive tracking control for moving targets with velocity observation

“…Flight processes of take-off and target search stages in the work by Shi et al (2023) are combined in experiments for complete implementation, and the proposed method is treated as the IBVS stage. Target poses are recorded by the Jackal odometer, and UAV poses are recorded by VINS-Mono (Tong et al, 2018).…”

“…T are linear and angular velocities of the UAV under F r , respectively; mg is UAV gravity; J is the UAV inertial matrix; e 3 : = ½0, 0, 1 T represents a unit vector; F(t) 2 R 3 is a force input vector along F r axes; and U (t) is total thrust of four propellers (Shi et al, 2023). By utilizing small angle approximation principle, Jacobian relationship between w(t) and h(t) variation is obtained as _ h(t) = w(t) in UAV actual flight (Shi et al, 2023).…”

“…Figure 1 shows configuration of UAV-vision object tracking, and detailed kinematics and dynamics models of a UAV are described in the work by Shi et al (2023). The world frame F w is fixed at initial centroid of the visual target with directions of east-north-up, and the body frame F r is located at the mass center of the UAV with directions of front-left-up.…”

“…The pixel coordinate of bold-italicP v ( t ) on the virtual image plane is denoted as ( u v ( t ) , n v ( t ) ) , and its time derivative is (Shi et al, 2023)…”