This paper presents a methodology and the experimental validation for collaborative load transportation using two UAVs (Unmanned Aerial Vehicles). The state variables are estimated, based on measurements from motion sensors installed on-board. Control and estimation solutions were required to ensure the stability of the system, while guaranteeing null steady-state position and estimation errors. The vertical velocity is also estimated since there is no sensor on-board the UAVs capable of providing this measure directly. The relative position between the UAVs is estimated using only on-board sensors and images acquired by the UAV front camera. The controllers and estimators resort to linear and optimal control techniques, as the Linear Quadratic Regulators and Kalman filters. The proposed control system is validated both in simulation and experimentally, resorting to a commercially available quadrotor equipped with an Inertial Measurement Unit, an ultrasound height sensor, vertical and frontal cameras.

本文介绍了使用两个无人机（无人飞行器）进行协同负载运输的方法和实验验证。根据安装在板上的运动传感器的测量值估算状态变量。需要控制和估计解决方案以确保系统的稳定性，同时还要保证零稳态位置和估计误差。由于无人机上没有能够直接提供这种测量的传感器，因此也可以估算垂直速度。无人机之间的相对位置仅使用机载传感器和无人机前置摄像头采集的图像进行估算。控制器和估计器采用线性和最优控制技术，例如线性二次调节器和卡尔曼滤波器。