Robust Control for Unmanned Aerial Manipulator Under Disturbances

Yanjie Chen,Bingwei He,Yaonan Wang,Zhiqiang Miao,Xiaofang Yuan,Lixiong Lin,Weiwei Zhan

doi:10.1109/access.2020.3008971

Abstract

Unmanned aerial manipulator (UAM) is usually a combination of a quadrotor and a robotic arm that can exert active influences on the environments. The control problems of the UAM system include model uncertainty caused by its center of gravity shift and external disturbances from the environments. To handle these two disturbances, a tracking control strategy is proposed for position and attitude control of the UAM in this paper. In particular, the model of the UAM is established considering with center of gravity shift and disturbances from environments. In the position control, both internal disturbances and external disturbances are compensated by using a sliding mode controller. In the attitude control, an adaptive law is designed to estimate internal disturbances, and a disturbance observer is designed to estimate external disturbances. The stability analysis of the proposed controller is provided and the effectiveness of the proposed method is verified in simulation.

Highlights

Unmanned aerial robot systems have been substantially attracted researchers’ attention all over the world due to their hovering and aggressive maneuvering ability [1]
The internal disturbances created by the center of gravity shift will affect the stability of the unmanned aerial manipulator (UAM)
To illustrate the performance clearly, the compared results in two scenarios based on the Root Mean Squared Error (RMSE) criterion are provided in Table 3 and Table 4 respectively

Summary

INTRODUCTION

Unmanned aerial robot systems have been substantially attracted researchers’ attention all over the world due to their hovering and aggressive maneuvering ability [1]. The center of gravity (CoG) is different from its modeling value when the robotic arm moves or grasps objects This error can be regarded as an internal disturbance, which has been investigated by much previous research. The contributions of this paper are listed as follows: 1) Considering to internal and external disturbances, the position controller is designed to ensure the tracking performance of the UAM under both these disturbances. Based on the sliding mode controller, the traditional symbolic function is replaced by a saturation function, and a robust term is adopted to ensure that the intermediate variable is smooth In this way, the problem of position deviation caused by the internal and external disturbances can be solved.

PRELIMINARIES

CONTROLLER DESIGN

SIMULATION VERIFICATION

RESULTS AND ANALYSIS

CONCLUSION