Accurate Tracking of Aggressive Quadrotor Trajectories using Incremental Nonlinear Dynamic Inversion and Differential Flatness

Autonomous unmanned aerial vehicles (UAVs) that can execute aggressive (i.e., high-speed and high-acceleration) maneuvers have attracted significant attention in the past few years. This paper focuses on accurate tracking of aggressive quadcopter trajectories. We propose a novel control law for tracking of position and yaw angle and their derivatives of up to fourth order, specifically, velocity, acceleration, jerk, and snap along with yaw rate and yaw acceleration. Jerk and snap are tracked using feedforward inputs for angular rate and angular acceleration based on the differential flatness of the quadcopter dynamics. Snap tracking requires direct control of body torque, which we achieve using closed-loop motor speed control based on measurements from optical encoders attached to the motors. The controller utilizes incremental nonlinear dynamic inversion (INDI) for robust tracking of linear and angular accelerations despite external disturbances, such as aerodynamic drag forces. Hence, prior modeling of aerodynamic effects is not required. We rigorously analyze the proposed control law through response analysis, and we demonstrate it in experiments. The controller enables a quadcopter UAV to track complex 3D trajectories, reaching speeds up to 12.9 m/s and accelerations up to 2.1g, while keeping the root-mean-square tracking error down to 6.6 cm, in a flight volume that is roughly 18 m by 7 m and 3 m tall. We also demonstrate the robustness of the controller by attaching a drag plate to the UAV in flight tests and by pulling on the UAV with a rope during hover.Comment: To be published in IEEE Transactions on Control Systems Technology. Revision: new set of experiments at increased speed (up to 12.9 m/s), updated controller design using quaternion representation, new video available at https://youtu.be/K15lNBAKDC

Master of Science

thesisThis thesis provides details on the development of automatic collision avoidance for manually tele-operated unmanned aerial vehicles. We note that large portions of this work are also reprinted with permission, from 2014 IEEE International Conference on Robotics and Automation, \Automatic Collision Avoidance for Manually Tele-operated Unmanned Aerial Vehicles", by J. Israelsen, M. Beall, D. Bareiss, D. Stuart, E. Keeney, and J. van den Berg c 2014 IEEE. We provide a method to aid the operator of unmanned aerial vehicles. We do this by automatically performing collision avoidance with obstacles in the environment. Our method allows the operator to focus on the overall motion of the vehicle rather than requiring the operator to perform collision avoidance. Where other currently existing systems override the controls of the operator only as a last resort, our approach was developed such that the operator can rely on the automatic collision avoidance for maneuverability. Given the current operator control input, our approach continually determines the future path of the vehicle. If along the future path a collision is predicted, then our algorithm will minimally override the operator's control such that the vehicle will not collide with the obstacles in the environment. Such an approach ensures the safety of the operator's controls while simultaneously maintaining the original intent of the operator. We successfully implemented this approach in a simulated environment, as well as on a physical quadrotor system in a laboratory environment. Our experiments show that, even when intentionally trying to do so, the operator failed to crash the vehicle into environment obstacles

Utilization of a Geodesic Sphere and Quadcopter as Two-Way Field Probe for Electro-Magnetic Field Measurements in an Indoor Radar Cross Section Range

Radar Cross Section (RCS) measurements rely heavily on multiple assumptions. Uncertainty in the final measurement is determined based on these assumptions. One source in particular is the non-homogeneous nature of the transmission path between radar test equipment and a target under test. The following research extends prior research. This thesis intends to provide a unique two-way field probe solution for measuring Electro-magnetic (EM) fluctuations in a test volume. In this thesis, the design, development, and demonstration of a geodesic sphere encased quadcopter two-way probe is explained. The Parrot® Bebop Drone quadcopter was used with a 2v frequency divided geodesic sphere design. Position and pose data was accomplished with a Vicon™ motion capture system. And a Lintek 4000 radar instrumentation system provided RCS measurements. Many major system design considerations were discovered. The geodesic sphere to quadcopter interface should not interfere with flight characteristics. RCS measurements with position and pose data synchronization is important. And the sample points captured must be sufficient to extract any conclusions. This research concluded that a geodesic sphere and quadcopter could be used as a two-way probe to measure general field characteristics of an indoor compact RCS range. In a quadcopter only flight test, using a 2 to 5 GHz frequency sweep at 0.1 GHz increments, there were three instances where a direct correlation in phase measurement to flight path was observed. Further research is required to better understand the quality of the field measurements

Sistema de posicionamento externo multi-câmara

A necessidade de informação externa, de referência, acerca da atitude e posição de um dado robô constitui a motivação da presente dissertação, onde foram desenvolvidos algoritmos para auxílio na navegação, ou simplesmente para aferição e validação da resposta do sistema autónomo ao meio envolvente. O principal contributo passa pelo desenvolvimento de um sistema de posicionamento externo multi-câmara, que determina a localização e atitude de sistemas robóticos ou objetos, com base em marcadores óticos ativos. Através da caracterização dos sistemas robóticos e dos cenários de atuação, percebe-se a necessidade de desenvolver um sistema de visão constituído por multi-câmaras para endereçar as situações de oclusão, aumentar a cobertura espacial e potenciar a qualidade dos resultados de posicionamento. Assim é proposta uma arquitetura para um sistema global dirigido aos vários requisitos identificados. A utilização de múltiplas câmaras e objetos de interesse munidos de um conjunto de marcadores ativos, torna viável o seguimento em tempo real destes objetos, em ambiente terrestre, aéreo ou subaquático. Esta arquitetura do sistema global, é demonstrada através de um sistema composto por três câmaras e uma plataforma de quatro Light-Emitting Diodes (LEDs) para validação de múltiplos módulos de software, nomeadamente: identificação e validação de pontos de interesse em imagens; cálculo da posição tridimensional dos marcadores através da combinação de pares de câmaras stereo e geometria 'multi view'; seleção de resultados mais precisos; cálculo da atitude do alvo. Para validação do sistema implementado, foram realizados ensaios experimentais que demonstram o correto funcionamento dos vários módulos do sistema, para diversas configurações e condicionantes. Simultaneamente, instalaram-se dois dispositivos comerciais (Faro e Pixhawk) para aferição e comparação de resultados. Os resultados experimentais mostraram uma clara vantagem do sistema de posicionamento multi-câmara face ao stereo, quer em qualidade de informação de posicionamento obtida, quer nos aspetos de cobertura espacial e oclusões.This dissertation aims to contribute to development Groundtruth System of Multicamera Vision that is also to determinate the pose of robotic systems or objects based on active optical markers. The focus of this thesis is the absence of external information about the target’s attitude to correct navigation algorithms or simply to validate the answer of autonomous system to the surrounding environment. Through the description of the robotic systems in site, it was noticed there was a need to develop a vision system constituted by multi cameras, to address occlusion situations, increase the floor space and up-level the results accuracy. Highly motivated, it is proposed architecture for a global system facing the multiple identified requirements. By using multiple cameras and objects of interest with several active markers, it has become possible to follow objects in real time different environments such as land, air or underwater. Regarding about of global architecture system, it is presented a contribution through a system composed by three cameras and a platform with four Light-Emitting Diodes (LEDs) to validate the points of interest on images. Through this process, it is also possible to measure the tridimensional position of the markers using stereo cameras pairs with different combinations and multi view triangulation, in order to obtain a precise selection of results and targets attitude measurement. In order to validate the implemented system, it were performed several trials showing that the system multiple modules converge to the ideal results under various conditions. Simultaneously, two commercial devices were set up and used (Faro Focus and Pixhawk) to compare results of position and attitude

Controlled manipulation using autonomous aerial systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 134-135).The main focus of the thesis is to design and control Autonomous Aerial Systems, also referred to as Unmanned Aerial Vehicles (UAVs). UAVs are able to hover and navigate in space using the thrust forces generated by the propellers. One of the simplest such vehicles that is widely used is a Quadrotor. While UAVs have been predominantly used for "fly and sense" applications, very few investigations have focused on using them to perform manipulation by contact. The latter is challenging because of the dual goal of performing manipulation and maintaining stable flight. Because Quadrotors can quickly reach a location, their ability to manipulate can be impactful in many scenarios. While efficient flight control of Quadrotor has been an active research area, using Quadrotor to perform manipulation is novel and challenging. In this thesis, a range of Quadrotor designs and control strategies are proposed in order to carry out autonomous manipulation of objects. We first derive a dynamic model of the Quadrotor that accounts for the presence of contact, object dynamics and kinematics. To improve manipulation performance, a passive light-weight end-effector interface between the Quadrotor and the object is proposed. The complexity of the dynamics is systematically reduced by making certain assumptions. The resulting dynamic model is divided into nonlinear subsystems on the basis of their degrees of freedom, for each of which separate controllers are designed. An efficient docking approach is proposed that permits fast and aggressive docking, even at very high speeds. Because a single Quadrotor UAS is limited in manipulation capability, a multi Quadrotor cooperative manipulation scheme is proposed. Control strategies are proposed to deal with kinematic and parametric uncertainties. A manipulation scheme to open a door with unknown hinge location is proposed. A nonlinear adaptive controller is implemented to perform efficient tracking in the presence of parametric uncertainty. In order to improve robustness to accidental contacts, a novel flexible Quadrotor, denoted as ParaFlex, is designed. The advantages of ParaFlex over a rigid Quadrotor are demonstrated. A Simulation, Test and Validation Environment (STeVE) is developed to facilitate smooth and efficient transition from design process to simulation to experiments.by Manohar B. Srikanth.Ph.D

Молодежь и современные информационные технологии : сборник трудов XVIII Международной научно-практической конференции студентов, аспирантов и молодых учёных, 22-26 марта 2021 г., г. Томск

Сборник содержит доклады, представленные на XVIII Международной научно-практической конференции студентов, аспирантов и молодых ученых «Молодежь и современные информационные технологии», прошедшей в Томском политехническом университете на базе Инженерной школы информационных технологий и робототехники. Материалы сборника отражают доклады студентов, аспирантов и молодых ученых, принятые к обсуждению на секциях: «Искусственный интеллект и машинное обучение», ««Цифровизация, IT и цифровая экономика», «Дизайн и компьютерная графика», «Виртуальная и дополненная реальность», «Технология больших данных в индустрии», «Мехатроника и робототехника», «Автоматизация технологических процессов и производств». Сборник предназначен для специалистов в области информационных технологий, студентов и аспирантов соответствующих специальностей