135 research outputs found
Nonlinear adaptive control of an aerial manipulation system
This paper presents the nonlinear adaptive control of a quadrotor endowed with a 2 degrees of freedom (DOF) manipulator. By considering the quadrotor and the robot arm as a combined system, complete modeling of the aerial manipulation system (AMS) has been presented using the Euler-Lagrange method. A hierarchical nonlinear control scheme which consists of outer and inner control loops has been utilized. Model Reference Adaptive Controller (MRAC) is designed for the outer loop where the required command signals are generated to force the quadrotor to move on a reference trajectory in the presence of uncertainties and reaction forces coming from the manipulator. For the inner loop, the attitude dynamics of the quadrotor and the dynamics of the 2-DOF robotic arm are considered as a fully actuated 5-DOF unified part of the AMS. Nonlinear adaptive control has been utilized for the low-level controller where the changes in inertias and the masses have been tackled along with the reaction forces acting on the attitude part of the AMS. The proposed technique has been validated through simulations in two different scenarios
A review of aerial manipulation of small-scale rotorcraft unmanned robotic systems
Small-scale rotorcraft unmanned robotic systems (SRURSs) are a kind of unmanned rotorcraft with manipulating devices. This review aims to provide an overview on aerial manipulation of SRURSs nowadays and promote relative research in the future. In the past decade, aerial manipulation of SRURSs has attracted the interest of researchers globally. This paper provides a literature review of the last 10 years (2008–2017) on SRURSs, and details achievements and challenges. Firstly, the definition, current state, development, classification, and challenges of SRURSs are introduced. Then, related papers are organized into two topical categories: mechanical structure design, and modeling and control. Following this, research groups involved in SRURS research and their major achievements are summarized and classified in the form of tables. The research groups are introduced in detail from seven parts. Finally, trends and challenges are compiled and presented to serve as a resource for researchers interested in aerial manipulation of SRURSs. The problem, trends, and challenges are described from three aspects. Conclusions of the paper are presented, and the future of SRURSs is discussed to enable further research interests
Multimodal Aerial Locomotion:An Approach to Active Tool Handling
The research focus in aerial robotics is shifting from contactless inspection toward interaction and manipulation, with the number of potential applications rapidly increasing [1]. Eventually, aerial manipulators, i.e., unmanned aerial vehicles (UAVs) equipped with manipulators, will likely take on hazardous maintenance tasks now performed by humans. For this to happen, aerial manipulators must be able to perform all the different operations required in these maintenance routines
Missions and Vehicle Concepts for Modern, Propelled, Lighter-Than-Air Vehicles
The results of studies conducted over the last 15 years to assess missions and vehicle concepts for modern, propelled, lighter-than-air vehicles (airships) were surveyed. Rigid and non-rigid airship concepts are considered. The use of airships for ocean patrol and surveillance is discussed along with vertical heavy lift airships. Military and civilian needs for high altitude platforms are addressed. Around 1970 a resurgence of interest about lighter-than-air vehicles (airships) occurred in both the public at large and in certain isolated elements of the aerospace industry. Such renewals of airship enthusiasm are not new and have, in fact, occurred regularly since the days of the Hindenburg and other large rigid airships. However, the interest that developed in the early 1970's has been particularly strong and self-sustaining for a number of good reasons. The first is the rapid increase in fuel prices over the last decade and the common belief (usually true) that airships are the most fuel efficient means of air transportation. Second, a number of new mission needs have arisen, particularly in surveillance and patrol and in vertical heavy-lift, which would seem to be well-suited to airship capabilities. The third reason is the recent proposal of many new and innovative airship concepts. Finally, there is the prospect of adapting to airships the tremendous amount of new aeronautical technology which has been developed in the past few decades thereby obtaining dramatic new airship capabilities. The primary purpose of this volume is to survey the results of studies, conducted over the last 15 years, to assess missions and vehicle concepts for modern propelled lighter-than-air vehicles
Aggressive Aerial Grasping using a Soft Drone with Onboard Perception
Contrary to the stunning feats observed in birds of prey, aerial manipulation
and grasping with flying robots still lack versatility and agility.
Conventional approaches using rigid manipulators require precise positioning
and are subject to large reaction forces at grasp, which limit performance at
high speeds. The few reported examples of aggressive aerial grasping rely on
motion capture systems, or fail to generalize across environments and grasp
targets. We describe the first example of a soft aerial manipulator equipped
with a fully onboard perception pipeline, capable of robustly localizing and
grasping visually and morphologically varied objects. The proposed system
features a novel passively closing tendon-actuated soft gripper that enables
fast closure at grasp, while compensating for position errors, complying to the
target-object morphology, and dampening reaction forces. The system includes an
onboard perception pipeline that combines a neural-network-based semantic
keypoint detector with a state-of-the-art robust 3D object pose estimator,
whose estimate is further refined using a fixed-lag smoother. The resulting
pose estimate is passed to a minimum-snap trajectory planner, tracked by an
adaptive controller that fully compensates for the added mass of the grasped
object. Finally, a finite-element-based controller determines optimal gripper
configurations for grasping. Rigorous experiments confirm that our approach
enables dynamic, aggressive, and versatile grasping. We demonstrate fully
onboard vision-based grasps of a variety of objects, in both indoor and outdoor
environments, and up to speeds of 2.0 m/s -- the fastest vision-based grasp
reported in the literature. Finally, we take a major step in expanding the
utility of our platform beyond stationary targets, by demonstrating
motion-capture-based grasps of targets moving up to 0.3 m/s, with relative
speeds up to 1.5 m/s
Nonlinear Model Predictive Control for the Stabilization of a Wheeled Unmanned Aerial Vehicle on a Pipe
This letter addresses the task of stabilizing a wheeled unmanned aerial vehicle on a pipe, which is an emerging applica- tion in oil and gas facilities for nondestructive measurements. After the derivation of the dynamic model of the system, a discrete-time nonlinear model predictive controller is designed over a finite horizon. The analysis of the asymptotic stability of the designed controller is carried out. Numerical tests show the performance and the robustness of the proposed solution
Robust nonlinear trajectory controllers for a single-rotor UAV with particle swarm optimization tuning
This paper presents the utilization of robust nonlinear control schemes for a single-rotor unmanned aerial vehicle (SR-UAV) mathematical model. The nonlinear dynamics of the vehicle are modeled according to the translational and rotational motions. The general structure is based on a translation controller connected in cascade with a P-PI attitude controller. Three different control approaches (classical PID, Super Twisting, and Adaptive Sliding Mode) are compared for the translation control. The parameters of such controllers are hard to tune by using a trial-and-error procedure, so we use an automated tuning procedure based on the Particle Swarm Optimization (PSO) method. The controllers were simulated in scenarios with wind gust disturbances, and a performance comparison was made between the different controllers with and without optimized gains. The results show a significant improvement in the performance of the PSO-tuned controllers.Peer ReviewedPostprint (published version
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