Flapping wings are a bio-inspired method to produce lift and thrust in aerial robots, leading to quiet and efficient motion. The advantages of this technology are safety and maneuverability, and physical interaction with the environment, humans, and animals. However, to enable substantial applications, these robots must perch and land. Despite recent progress in the perching field, flapping-wing vehicles, or ornithopters, are to this day unable to stop their flight on a branch. In this paper, we present a novel method that defines a process to reliably and autonomously land an ornithopter on a branch. This method describes the joint operation of a flapping-flight controller, a close-range correction system and a passive claw appendage. Flight is handled by a triple pitch-yaw-altitude controller and integrated body electronics, permitting perching at 3 m/s. The close-range correction system, with fast optical branch sensing compensates for position misalignment when landing. This is complemented by a passive bistable claw design can lock and hold 2 Nm of torque, grasp within and can re-open thanks to an integrated tendon actuation. The perching method is supplemented by a four-step experimental development process which optimizes for a successful design. We validate this method with a 700 g ornithopter and demonstrate the first autonomous perching flight of a flapping-wing robot on a branch, a result replicated with a second robot. This work paves the way towards the application of flapping-wing robots for long-range missions, bird observation, manipulation, and outdoor flight.
This work is concerned with the mechanical design and the description of the different components of a novel mobile base for a flexible mobile manipulator. A flexible mobile manipulator is normally composed of multiple flexible links mounted on a mobile platform. This work is focused on the description of the mobile platform. The mobile platform of this work has two different configurations in order to carry out different tasks. Also, some hypothesis and experimental results are shown in this work as a first step to be able to obtain a kinematic model of the system later.
The gravity compensation of flexible link manipulators using mechanisms based on counterweights has been previously studied in the research literature. However, as far as we are concerned, no attempt has been done to study the difficulties and benefits of constructing mechanisms for the same purposes based on springs. This paper presents a gravitational mechanism based on springs for a single-link flexible arm. In specific, we address the mechanical design of the mechanism and the dynamic modeling of the resulting system. To assess the effectiveness of the mechanism and the validity of the dynamic model, we present experimental results.
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