Design Of A Vision-Guided Aerial Manipulator System

Aerial manipulator(AM)is a new type of robot with active operation ability in the air,which is composed of the flying robot(FR)and the operating device.Due to its high flexibility,strong maneuverability,hovering ability and other characteristics,the robot can quickly reach the high-risk complex environment where it is difficult for staff and ground robots to enter to perform tasks such as information acquisition and operations,which greatly expands the application field of the FR.In this paper,aiming at the difficulty of relative positioning between the FR and the grabbed target when the AM performs the tasks of grabbing,dropping,etc.,a design method of vision-guided AM is proposed under the outdoor condition of no motion capture system.This paper introduces the whole mechanism design of the AM and establishes the kinematics model of the FR,the kinematics model of the operating device and the dynamics model of the combined system.The AM is composed of a quadrotor and an operating device,including a 3 degree of freedom(DoF)manipulator and a single DoF gravity balance mechanism,which are mounted symmetrically under the frame of the quadrotor.The essence of the marker-based camera pose estimation is that under the premise that the parameters in the camera have been calibrated and the coordinates of several feature points are known,the coordinates and rotation angles of the camera in the coordinate system of the marker are solved by imaging the feature points in the camera photo.In this paper,the ArUco marker is selected.On the premise that its size is known and the internal parameters of the camera have been calibrated,the ArUco marker on the captured target is detected by the airborne monocular camera,and the camera pose is solved by the perspective-N-point(PNP)algorithm,so as to obtain the pose information of the FR.Then,the control system is divided into two levels: the FR control and operating device control.Based on the pose information of the FR,a visual guided hierarchical control method of the FR and operating device is designed.The method of visual guidance based on the ArUco marker designed above is verified by experiments.Firstly,a set of pose comparison standards and experimental methods for stationary experiments and outdoor hovering experiments are designed.The stationary and outdoor hovering experiments are conducted respectively.The stationary accuracy within 90 cm is within 0.2 cm,and the outdoor hovering accuracy within 50 cm is within 2.5 cm.Finally,the validity and rationality of visual guidance are further verified by independently grabbing a tubular column with a diameter of 2 cm,a length of 30 cm and a mass of 100 g.