Abstract-Robots capable of hover flight in constrained indoor environments have many applications, however their range is constrained by the high energetic cost of airborne locomotion. Perching allows flying robots to scan their environment without the need to remain aloft. This paper presents the design of a mechanism that allows indoor flying robots to attach to vertical surfaces. To date, solutions that enable flying robot with perching capabilities either require high precision control of the dynamics of the robot, or a mechanism robust to high energy impacts. In this article, we propose a perching mechanism comprising a compliant deployable pad and a passive selfalignment system, that does not require any active control during the attachment procedure. More specifically, a perching mechanism using fibre-based dry adhesives was implemented on a 300 g flying platform. An adhesive pad was first modeled and optimized in shape for maximum attachment force at the low pre-load forces inherent to hovering platforms. It was then mounted on a deployable mechanism that stays within the structure of the robot during flight and can be deployed when a perching manoeuvre is initiated. Finally, the perching mechanism is integrated onto a real flying robot and successful perching manoeuvres are demonstrated as a proof of concept.

Abstract-This paper addresses the problem of adequately protecting flying robots from damage resulting from collisions that may occur when exploring constrained and cluttered environments. A method for designing protective structures to meet the specific constraints of flying systems is presented and applied to the protection of a small coaxial hovering platform. Protective structures in the form of Euler springs in a tetrahedral configuration are designed and optimised to elastically absorb the energy of an impact while simultaneously minimizing the forces acting on the robot's stiff inner frame. These protective structures are integrated into a 282 g hovering platform and shown to consistently withstand dozens of collisions undamaged.

Abstract-Autonomous navigation in obstacle-dense indoor environments is very challenging for flying robots due to the high risk of collisions, which may lead to mechanical damage of the platform and eventual failure of the mission. While conventional approaches in autonomous navigation favor obstacle avoidance strategies, recent work showed that collisionrobust flying robots could hit obstacles without breaking and even self-recover after a crash to the ground. This approach is particularly interesting for autonomous navigation in complex environments where collisions are unavoidable, or for reducing the sensing and control complexity involved in obstacle avoidance. This paper aims at showing that collision-robust platforms can go a step further and exploit contacts with the environment to achieve useful navigation tasks based on the sense of touch. This approach is typically useful when weight restrictions prevent the use of heavier sensors, or as a low-level detection mechanism supplementing other sensing modalities.In this paper, a solution based on force and inertial sensors used to detect obstacles all around the robot is presented. Eight miniature force sensors, weighting 0.9g each, are integrated in the structure of a collision-robust flying platform without affecting its robustness. A proof-of-concept experiment demonstrates the use of contact sensing for exploring autonomously a room in 3D, showing significant advantages compared to a previous strategy. To our knowledge this is the first fully autonomous flying robot using touch sensors as only exteroceptive sensors.

We aim at developing ultralight autonomous microflyers capable of freely flying within houses or small built environments while avoiding collisions. Our latest prototype is a fixed-wing aircraft weighing a mere 10 g, flying around 1.5 m/s and carrying the necessary electronics for airspeed regulation and lateral collision avoidance. This microflyer is equipped with two tiny camera modules, two rate gyroscopes, an anemometer, a small microcontroller, and a Bluetooth radio module. Inflight tests are carried out in a new experimentation room specifically designed for easy changing of surrounding textures.keywords: indoor flying robot, vision-based navigation, collision avoidance, optic flow.

Abstract-This paper presents a new paradigm in the design of indoor flying robots that replaces collision avoidance with collision robustness. Indoor flying robots must operate within constrained and cluttered environments where even nature's most sophisticated flyers such as insects cannot avoid all obstacles and should thus be able to withstand collisions and recover from them autonomously. A prototype platform specifically designed to withstand collisions and recover without human intervention is presented. Its dimensions are optimized to fulfill the varying constraints of aerodynamics, robustness and self-recovery, and new construction techniques focusing on shock absorption are presented. Finally, the platform is tested both in-flight and during collisions to characterize its collision robustness and self-recovery capability.

Abstract-Research made over the past decade shows the use of increasingly complex methods and heavy platforms to achieve autonomous flight in cluttered environments. However, efficient behaviors can be found in nature where limited sensing is used, such as in insects progressing toward a light at night. Interestingly, their success is based on their ability to recover from the numerous collisions happening along their imperfect flight path. The goal of the AirBurr project is to take inspiration from these insects and develop a new class of flying robots that can recover from collisions and even exploit them. Such robots are designed to be robust to crashes and can take-off again without human intervention. They navigate in a reactive way, bump into obstacles, and unlike conventional approaches, they don't need heavy modeling in order to fly autonomously. We believe that this new paradigm will bring flying robots out of the laboratory and allow them to tackle unstructured, cluttered environments.This paper aims at presenting the vision of the AirBurr project, as well as the latest results in the design of a platform capable of sustaining collisions and self-recovering after crashes.Index Terms-Robust bio-inspired indoor flying robot.

Abstract-We aim at developing ultralight autonomous microflyers capable of navigating within houses or small built environments. Our latest prototype is a fixed-wing aircraft weighing a mere 10 g, flying around 1.5 m/s and carrying the necessary electronics for airspeed regulation and collision avoidance. This microflyer is equipped with two tiny camera modules, two rate gyroscopes, an anemometer, a small microcontroller, and a Bluetooth radio module. In-flight tests are carried out in a new experimentation room specifically designed for easy changing of surrounding textures. I. CHALLENGES AND STATE OF THE ARTThere are currently no autonomous flying robots capable of navigating indoors, within enclosed environments such as offices or houses. Although they could be useful in many applications such as surveillance, hazardous environment exploration, search and rescue, etc., the challenges engineers are facing to develop such robots are numerous. In order to be able to fly at very low speed (below 2 m/s) such flying systems must be ultra-lightweight (usually well below 50 g), which implies tremendous constraints in terms of embedded computational power, sensor simplicity, and airframe architecture. Moreover, controlling such systems is quite different from controlling more conventional outdoor micro aerial vehicles, which can rely on high-precision inertial measurement units, global positioning systems, radars or other conventional distance sensors, and/or visual horizon detection systems [1]- [3].In this paper we present the latest prototype resulting from our research in the domain of indoor microflyers since 2001 [4]-[7]. This robot, called MC1, has an overall weight of 10 g including visual, inertial, and air flow sensors, which enable a certain degree of autonomy: automatic take-off, speed regulation, and collision avoidance. These capabilities have been demonstrated in a 7x6-m room equipped with randomly textured walls.To the best of our knowledge, the MC1 is the lightest motorized free-flying robot produced to date. Oh and collaborators have been working on automatic landing and collision avoidance with an indoor flying robot weighing around 30 g [8], [9]. However, these experiments were carried out in relatively large indoor environments such as basketball courts and only one vision sensor was embedded at one time allowing In summer 2004, we demonstrated the first visually-guided free-flying indoor aircraft. This was done with an earlier prototype (designated F2) weighing 30 g and flying in a 16x16-m room equipped with evenly-distributed black and white vertical stripes made of suspended fabrics. The experiment consisted of having the 80-cm-wingspanned aircraft autonomously steer like a fly, i.e., following straight trajectories when far from any walls and engaging a fast left or right turn when close to a wall (see [7] for details).With the 10-gram MC1 described in this paper, we made three significant steps forward since then:1) The overall weight of the robot has been reduced from 30 g to 10 g while the...

Abstract-Flying robots have unique advantages in the exploration of cluttered environments such as caves or collapsed buildings. Current systems, however, have difficulty in dealing with the large amount of obstacles inherent to such environments. Collisions with obstacles generally result in crashes from which the platform can no longer recover. This paper presents a method to design active uprighting mechanisms for protected rotorcrafttype flying robots that allow them to become upright and subsequently take off again after an otherwise mission-ending collision. This method is demonstrated on a tailsitter flying robot, which is capable of consistently uprighting after falling on its side using a spring-based "leg" and returning to the air to continue its mission.