Current bioinspired flapping-wing micro aerial robots incorporate numerous capabilities pulled from the study of insect morphologies, and have utilized these designs to improve flight stability, time, and energy efficiency. However, this approach to design of robotic systems draws unidirectionally from the threshold of biology into robotics, pulling from the mechanisms and mechanics that evolutionary biology has spent millennia iterating, without utilizing these robots to further study insect and animal traits. In this research we develop a flapping-wing micro-aerial robot, scaled up in size from the Harvard RoboBee, designed as a platform for studying the control mechanisms inherent in insect muscle physiology. A concomitant velocity sensing circuit is implemented in a piezoelectric actuator, to self-sense the velocity of the actuator tip and feed it into a control feedback loop. The loop simulates antagonistic delay-stretch activation muscles, mimicking insects that fly asynchronously. Using the concomitant sensing and Upscaled Robobee, the system generates stable oscillatory flapping-wing motion without the use of large off-board displacement sensors across a range of control parameters, and performs as a platform for future DSA control studies.
Despite the prevalence of insect flight as a form of locomotion in nature, manmade aerial systems have yet to match the aerial prowess of flying insects. Within a tiny body volume, flying insects embody the capabilities to flap seemingly insubstantial wings at very high frequencies and sustain beyond their own body weight in flight. A precise authority over their wing motions enables them to respond to obstacles and threats in flight with unrivaled speed and grace.
Flying insects exhibit a remarkable ability to fly in environments that are small, cluttered and highly dynamic. Inspired by these animals, scientist have made great strides in understanding the aerodynamic mechanisms behind insect-scale flapping-wing flight. By applying these mechanisms together with recent advances in meso-scale fabrication techniques, engineers built an insect-scale flapping-wing robot and demonstrated hover by actively controlling the robot about its roll and pitch axes. The robot, however, lacked control over its yaw axis preventing control over its heading angle.
Flying insects are intelligent micromachines capable of exquisite maneuvers in unpredictable environments. Understanding these systems advances our knowledge of flight control, sensor suites, and unsteady aerodynamics, which is of crucial interest to engineers developing intelligent flying robots or micro air vehicles (MAVs). The insights we gain when synthesizing bioinspired systems can in turn benefit the fields of neurophysiology, ethology and zoology by providing real-life tests of the proposed models. This book was written by biologists and engineers leading the research in this crossdisciplinary field. It examines all aspects of the mechanics, technology and intelligence of insects and insectoids. After introductory-level overviews of flight control in insects, dedicated chapters focus on the development of autonomous flying systems using biological principles to sense their surroundings and autonomously navigate. A significant part of the book is dedicated to the mechanics and control of flapping wings both in insects and artificial systems. Finally hybrid locomotion, energy harvesting and manufacturing of small flying robots are covered. A particular feature of the book is the depth on realization topics such as control engineering, electronics, mechanics, optics, robotics and manufacturing. This book will be of interest to academic and industrial researchers engaged with theory and engineering in the domains of aerial robotics, artificial intelligence, and entomology.
This book introduces the topics most relevant to autonomously flying flapping wing robots: flapping-wing design, aerodynamics, and artificial intelligence. Readers can explore these topics in the context of the "Delfly", a flapping wing robot designed at Delft University in The Netherlands. How are tiny fruit flies able to lift their weight, avoid obstacles and predators, and find food or shelter? The first step in emulating this is the creation of a micro flapping wing robot that flies by itself. The challenges are considerable: the design and aerodynamics of flapping wings are still active areas of scientific research, whilst artificial intelligence is subject to extreme limitations deriving from the few sensors and minimal processing onboard. This book conveys the essential insights that lie behind success such as the DelFly Micro and the DelFly Explorer. The DelFly Micro, with its 3.07 grams and 10 cm wing span, is still the smallest flapping wing MAV in the world carrying a camera, whilst the DelFly Explorer is the world's first flapping wing MAV that is able to fly completely autonomously in unknown environments. The DelFly project started in 2005 and ever since has served as inspiration, not only to many scientific flapping wing studies, but also the design of flapping wing toys. The combination of introductions to relevant fields, practical insights and scientific experiments from the DelFly project make this book a must-read for all flapping wing enthusiasts, be they students, researchers, or engineers.
Robots today, though capable of performing a growing number of increasingly complex tasks, lack the agility that would be required to perform in a rapidly changing or dynamic environment, especially when compared to animals and insects, they are very rigid in performance. Recent developments in the field of insect-scale flapping wing micro-robots include controlled hovering flight, sensor integration and controlled landing. However, their ability to perform rapid, dynamic motions has not been explored in depth. We present the design, fabrication, and actuation of a insect-sized (142~mg) aerial robot that is equipped with a bio-inspired tail. Incorporating a tail allows the robot to perform rapid inertial reorientation as well as to shift weight to actuate torques on its body. Here we present the first analysis of tail actuation using a piezo actuator, departing from previous work to date that has focused exclusively on actuation by DC motor. The primary difference is that unlike a geared motor system, the piezoelectric-tail system operates as a resonant system, exhibiting slowly-decaying oscillations. We present a dynamic model of piezo-driven inertial reorientation, along with an open-loop feedforward controller that reduces excitation of the resonant mode. Our results indicate that incorporating a tail can allow for more rapid dynamic maneuvers and could stabilize the robot during flight.
Insect-sized robots have numerous applications due to their small size. For example, they can go into confined spaces where humans or larger robots cannot. These applications include gas leak detections in pipelines, search and rescue in disaster response, and crop monitoring for smart agriculture. Insect-sized flapping-wing robots draw inspiration from nature's tiny machines such as flies and bees. Earlier iterations of these robots have successfully demonstrated hovering flight. However, there are some limitations to their abilities. Prior designs consist of many discrete parts that need to be manually assembled under a microscope. There are also limitations to their locomotion abilities. These robots could not control their heading while hovering, making them infeasible for many applications involving heading control and steering. Also, these robots relied on external sources for control feedback. This dissertation proposes a re-design of insect-sized flapping-wing robots: the UW Robofly. The idea behind the re-design is a robot that compares better with its biological counterparts in terms of autonomy. Autonomy in micro-robots can be quantified in the following three terms, which can be given equal importance: 1) Mobility autonomy, 2) power autonomy, and 3) control autonomy. In terms of mobility autonomy, the Robofly can perform multimodal locomotion, which includes ground, water surface, and aerial locomotion. The robot can also perform open-loop landing because its center of mass is closer to the ground. The robot is also easy to fabricate since it uses a folding mechanism that decreases the number of discrete components. Although hovering does not require a robot to control its heading, it is crucial for various applications, including image capture and video recording. A re-designed version of the UW Robofly, Robofly-Expanded, shows the ability to steer and control its heading while hovering, making it the first at this scale to control all six degrees of freedom with only two actuators. For power autonomy, the Robofly can carry a PV cell and onboard power electronics. It became the first robot at this scale to achieve wireless liftoff as a result of the efforts in power autonomy at UW. Lastly, control autonomy, which aims for the robot to hover without the need for motion feedback from offboard sensors such as a motion capture arena, is addressed. The robot requires at least three sensors onboard to make it hover about a point in space without drifting away. The proposed sensors are as follows-- 1) a MEMS gyroscope for attitude control, 2) an IR time-of-flight range sensor for altitude control, and 3) an optical flow sensor for lateral motion control in space. While earlier research has demonstrated flights with an onboard gyroscope and IR time-of-flight sensors, this research goes a step further and include an optical flow sensor onboard. A short flight demonstrating the ability of the robot to use the optical flow sensor data for lateral motion feedback is also presented. The work presented here overcomes significant limitations in previous work, bringing insect-sized flapping-wing robots much closer to full autonomous functionality and mobility. Future work now primarily entails further sensor integration, devising a controllable high-voltage power supply, and incorporating a power collection and storage system.
Controlled flight of insect scale ( 100 mg) Micro Aerial Vehicles (MAVs) has to date required offboard sensors and computation. Achieving autonomy in more general environment will require integrating sensors such as a camera onboard, but this is a challenging task because of the small scale as the component mass and computation must be minimized. In this work we present the design and fabrication of a low-weight camera 26 mg mounted on a flapping wing insect scale aerial and ground robot. We trained a Convolution Neural Network (CNN) with the images captured by the camera to classify flower and predator images. We show that feedback from the CNNs classification can command the robot to move toward flower and away from predator images. Our results indicate that these computations can be performed using low-weight microcontrollers compatible with the payload and power constraints of insect-scale MAVs. We also perform preliminary optic flow based position estimation experiments with the low weight camera. Many desired capabilities for aerial vehicles, such as landing site selection and obstacle detection and avoidance, are ill-defined. This work shows that Computer Vision (CV) and CNNs, which have previously been deployed only on larger robots, can now be used on insectscale for such tasks.
This book demonstrates how bio-inspiration can lead to fully autonomous flying robots without relying on external aids. Most existing aerial robots fly in open skies, far from obstacles, and rely on external beacons, mainly GPS, to localise and navigate. However, these robots are not able to fly at low altitude or in confined environments, and yet this poses absolutely no difficulty to insects. Indeed, flying insects display efficient flight control capabilities in complex environments despite their limited weight and relatively tiny brain size. From sensor suite to control strategies, the literature on flying insects is reviewed from an engineering perspective in order to extract useful principles that are then applied to the synthesis of artificial indoor flyers. Artificial evolution is also utilised to search for alternative control systems and behaviors that match the constraints of small flying robots. Specifically, the basic sensory modalities of insects, vision, gyroscopes and airflow sense, are applied to develop navigation controllers for indoor flying robots. These robots are capable of mapping sensor information onto actuator commands in real time to maintain altitude, stabilize the course and avoid obstacles. The most prominent result of this novel approach is a 10-gram microflyer capable of fully autonomous operation in an office-sized room using fly-inspired vision, inertial and airspeed sensors. This book is intended for all those interested in autonomous robotics, in academia and industry.
