Control of a multirotor outdoor aerial manipulator

Abstract

This paper presents the design and control of a multirotor-based aerial manipulator developed for outdoor operation. The multi-rotor has eight rotors and large payload to integrate a 7-degrees of freedom arm and to carry sensors and processing hardware needed for outdoor positioning. The arm can also carry an end-effector and sensors to perform different missions. The paper focuses on the control design and implementation aspects. A stable backstepping-based controller for the multirotor that uses the coupled full dynamic model is proposed, and an admittance controller for the manipulator arm is outlined. Several experimental tests with the aerial manipulator are also presented. In one of the experiments, the performance of the pitch attitude controller is compared to a PID controller. Other experiments of the arm controller following an object with the camera are also presented.

Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control

“…Figure 3 shows the results of two of them, which correspond to two multirotors of different size. The first one is the PQUAD quadrotor with four rotors of 12 cm radius and a total weight of 1,4 Kg, and the second one is the AMUSE multirotor [6], which has eight rotors of 20,5 cm radius and a total weight of 12 Kg. The ground plane has been placed at different distances from the rotor and a set of nine tests have been performed for each distance.…”

“…So, the four rotors and four images will be modelled, placing three dimensional sources in the same way as the previous section. For the case of a quadrotor with four coplanar rotors with a separation d from each rotor axis to its adjacent rotor axes, the sources of the rotors and its images will be 1,5 : (0, 0, ± ), 2,6 : (0, , ± ), 3,7 : ( , 0, ± ), and 4,8 : ( , , ± ), where , +4 represents the velocity potentials of the rotor and its rotor image ( + 4). Thus, the resultant expression of the increment in thrust due to the ground effect is the following: Figure 4 shows the increment in thrust for a quadrotor due to the ground effect with a dashed line and for a single rotor with a solid line for comparison.…”

“…These aerial manipulators [4][5][6], as they are usually known, extend the range of possible applications of UAVs. For instance, aerial manipulators can be used for the inspection and maintenance of industrial plants and infrastructures [7], aerial power lines, and moving objects [8] and taking samples of material from areas that are difficult to access.…”

Nonlinear Dynamics and Control of Aerial Robots

“…Moreover, the motion of arm induces disturbances to the quadcopter dynamics so the linear controllers lose their effectiveness during operation and sometime the closed loop system becomes unstable. In order to accomplish complex missions in presence of uncertainties in the environment, to achieve better maneuverability and precise 3D position and attitude control, nonlinear control techniques have been found effective [20][21][22][23][24][25][26][27], In Ref. [20] a set of nonlinear control laws have been proposed for aerial manipulator that provide asymptotic attitude and position tracking.…”

“…Backstepping-based nonlinear control scheme for automatic trajectory tracking for aerial manipulators has been proposed in Refs. [22,24].…”