Progresses in sensor technology, data processing and integrated actuators has made the development of miniature flying robots fully possible. Micro VTOL systems represent a useful class of flying robots because of their strong capabilities for small-area monitoring and building exploration. In this paper we describe the approach that our lab has taken to micro VTOL evolving towards full autonomy, and present the mechanical design, dynamic modelling, sensing, and control of our indoor VTOL autonomous robot OS4.

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Design and control of an indoor micro quadrotor

In this paper, we present two novel algorithms to realize a finite dimensional, linear time-invariant state-space model from input-output data. The algorithms have a number of common features. They are classified as one of the subspace model identification schemes, in that a major part of the identification problem consists of calculating specially structured subspaces of spaces defined by the input-output data. This structure is then exploited in the calculation of a realization. Another common feature is their algorithmic organization: an RQ factorization followed by a singular value decomposition and the solution of an overdetermined set (or sets) of equations. The schemes assume that the underlying system has an output-error structure and that a measurable input sequence is available. The latter characteristic indicates that both schemes are versions of the MIMO Output-Error State Space model identification (MOESP) approach. The first algorithm is denoted in particular as the (elementary MOESP scheme)...

Subspace model identification-Part 1. The output-error state-space model identification class of algorithms

Robotic systems are increasingly being utilized as fundamental data-gathering tools by scientists, allowing new perspectives and a greater understanding of the planet and its environmental processes. Today's robots are already exploring our deep oceans, tracking harmful algal blooms and pollution spread, monitoring climate variables, and even studying remote volcanoes. This article collates and discusses the significant advancements and applications of marine, terrestrial, and airborne robotic systems developed for environmental monitoring during the last two decades. Emerging research trends for achieving large-scale environmental monitoring are also reviewed, including cooperative robotic teams, robot and wireless sensor network (WSN) interaction, adaptive sampling and model-aided path planning. These trends offer efficient and precise measurement of environmental processes at unprecedented scales that will push the frontiers of robotic and natural sciences.

Robots for Environmental Monitoring: Significant Advancements and Applications

In the past decade Unmanned Aerial Vehicles (UAVs) have become a topic of interest in many research organizations. UAVs are finding applications in various areas ranging from military applications to traffic surveillance. This paper is a survey for a certain kind of UAV called quadrotor or quadcopter. Researchers are frequently choosing quadrotors for their research because a quadrotor can accurately and efficiently perform tasks that would be of high risk for a human pilot to perform. This paper encompasses the dynamic models of a quadrotor and the different model-dependent and model-independent control techniques and their comparison. Recently, focus has shifted to designing autonomous quadrotors. A summary of the various localization and navigation techniques has been given. Lastly, the paper investigates the potential applications of quadrotors and their role in multi-agent systems.

A survey of quadrotor Unmanned Aerial Vehicles

This thesis is about modelling, design and control of Miniature Flying Robots (MFR) with a focus on Vertical Take-Off and Landing (VTOL) systems and specifically, micro quadrotors. It introduces a mathematical model for simulation and control of such systems. It then describes a design methodology for a miniature rotorcraft. The methodology is subsequently applied to design an autonomous quadrotor named OS4. Based on the mathematical model, linear and nonlinear control techniques are used to design and simulate various controllers along this work. The dynamic model and the simulator evolved from a simple set of equations, valid only for hovering, to a complex mathematical model with more realistic aerodynamic coefficients and sensor and actuator models. Two platforms were developed during this thesis. The first one is a quadrotorlike test-bench with off-board data processing and power supply. It was used to safely and easily test control strategies. The second one, OS4, is a highly integrated quadrotor with on-board data processing and power supply. It has all the necessary sensors for autonomous operation. Five different controllers were developed. The first one, based on Lyapunov theory, was applied for attitude control. The second and the third controllers are based on PID and LQ techniques. These were compared for attitude control. The fourth and the fifth approaches use backstepping and sliding-mode concepts. They are applied to control attitude. Finally, backstepping is augmented with integral action and proposed as a single tool to design attitude, altitude and position controllers. This approach is validated through various flight experiments conducted on the OS4.

design and control of quadrotors with application to autonomous flying

This paper discusses Project AURORA (autonomous unmanned remote monitoring robotic airship) which focuses on the development of the control, navigation, sensing, and inference technologies required for substantially autonomous robotic airships. Our target application areas include the use of robotic airships for environmental, biodiversity, and climate research and monitoring. Based on typical mission requirements, we present arguments that favour airships over airplanes and helicopters as the ideal platforms for such missions. We outline the overall system architecture of the AURORA robotic airship, discuss its main subsystems, and mention the research and development issues involved.

A semi-autonomous robotic airship for environmental monitoring missions

Robotic unmanned aerial vehicles have great potential as surveying and instrument deployment platforms in the exploration of planets and moons with an atmosphere. Among the various types of planetary aerovehicles proposed, lighter-than-atmosphere (LTA) systems are of particular interest because of their extended mission duration and long traverse capabilities. In this paper, we argue that the unique characteristics of robotic airships make them ideal candidates for exploration of planetary bodies with an atmosphere. Robotic airships extend the capabilities of balloons through their flight controllability, allowing (1) precise flight path execution for surveying purposes, (2) long-range as well as close-up ground observations, (3) station-keeping for long-term monitoring of high science value sites, (4) transportation and deployment of scientific instruments and in situ laboratory facilities across vast distances, and (5) opportunistic flight path replanning in response to the detection of relevant sensor signatures. Implementation of these capabilities requires achieving a high degree of vehicle autonomy across a broad spectrum of operational scenarios. The paper outlines some of the core autonomy technologies required to implement the capabilities listed above, drawing on work and results obtained in the context of AURORA (Autonomous Unmanned Remote Monitoring Robotic Airship), a research effort that focuses on the development of the technologies required for substantially autonomous robotic airships. We discuss airship modeling and control, autonomous navigation, and sensor-based flight control. We also outline an approach to airborne perception and monitoring which includes mission-specific target acquisition, discrimination and identification, and present experimental results obtained with AURORA.

Robotic Airships for Exploration of Planetary Bodies with an Atmosphere: Autonomy Challenges

A new formulation of the equations of motion of an airship is derived to allow the analysis of the wind ine uence on the airship dynamics. Initially, theequations of motion arewritten via the Lagragian approach, considering the three kinetic energy terms associated with 1 ) the energy of the vehicle motion itself, 2 ) the energy of the air around the airship due to the relative velocities, and 3 ) the energy added to the buoyancy air. After that, the equations of motion are translated into Newton’ s second law formulation, yielding a new term, wind-induced force and torque. When the airship geometry approximated by an ellipsoid of revolution is considered the wind-induced terms are then explicitly derived, and their contribution on the longitudinal and lateral dynamics of the airship motion is analyzed. The results are illustrated using the model of a real airship, considering a given range of wind speed and a constant low airspeed.

Influence of Wind Speed on Airship Dynamics

Development of reliable control systems for semi-autonomous unmanned aerial vehicles require the use of extensive simulation data provided by an accurate six-degrees-of-freedom dynamic model. In this article we describe a Simulink-based control system development environment for Project AURORA's unmanned robotic airship, as well as the control algorithms and supervisory level of AURORA's control system. A complete take-off to landing mission illustrates the utilization of this environment.

A control system development environment for AURORA's semi-autonomous robotic airship

Addresses the issue of automatic hovering of an outdoor autonomous airship using image-based visual servoing. The hovering controller is designed using a full dynamic model of the airship, in a PD error feedback scheme, taking the visual signals as output and extracted from an on-board camera. The behavior and stability of the airship motion during the task execution and subjected to the wind disturbance is studied. The approach is finally validated in simulation using an accurate airship model.

S.S. Bueno

Papers

A semi-autonomous robotic airship for environmental monitoring missions

Robotic Airships for Exploration of Planetary Bodies with an Atmosphere: Autonomy Challenges

Influence of Wind Speed on Airship Dynamics

A control system development environment for AURORA's semi-autonomous robotic airship

Visual servo control for the hovering of all outdoor robotic airship