Designing Minimal and Scalable Insect-Inspired Multi-Locomotion Millirobots

In ant colonies, collectivity enables division of labour and resources with great scalability. Beyond their intricate social behaviours, individuals of the genus Odontomachus, also known as trap-jaw ants, have developed remarkable multi-locomotion mechanisms to ‘escape-jump’ upwards when threatened, using the sudden snapping of their mandibles, and to negotiate obstacles by leaping forwards using their legs. Emulating such diverse insect biomechanics and studying collective behaviours in a variety of environments may lead to the development of multi-locomotion robotic collectives deployable in situations such as emergency relief, exploration and monitoring; however, reproducing these abilities in small-scale robotic systems with simple design and scalability remains a key challenge. Existing robotic collectives are confined to two-dimensional surfaces owing to limited locomotion, and individual multi-locomotion robots are difficult to scale up to large groups owing to the increased complexity, size and cost of hardware designs, which hinder mass production. Here we demonstrate an autonomous multi-locomotion insect-scale robot (millirobot) inspired by trap-jaw ants that addresses the design and scalability challenges of small-scale terrestrial robots. The robot’s compact locomotion mechanism is constructed with minimal components and assembly steps, has tunable power requirements, and realizes five distinct gaits: vertical jumping for height, horizontal jumping for distance, somersault jumping to clear obstacles, walking on textured terrain and crawling on flat surfaces. The untethered, battery-powered millirobot can selectively switch gaits to traverse diverse terrain types, and groups of millirobots can operate collectively to manipulate objects and overcome obstacles. We constructed the ten-gram palm-sized prototype—the smallest and lightest self-contained multi-locomotion robot reported so far—by folding a quasi-two-dimensional metamaterial sandwich formed of easily integrated mechanical, material and electronic layers, which will enable assembly-free mass-manufacturing of robots with high task efficiency, flexibility and disposability.

A Soft Robot for Random Exploration of Terrestrial Environments

Dario Floreano, Stefano Mintchev, Jérémie Willemin, Davide Zappetti

A swarm of randomly moving miniature robots is an effective solution for the exploration of unknown terrains. However, the deployment of a swarm of miniature robots poses two challenges: finding an adequate locomotion strategy for fast exploration and obstacles negotiation; and implementing simple design and control solutions suited for mass manufacturing. Here, we tackle these challenges by developing a new soft robot with a minimalistic design and a simple control strategy that can randomly propel itself above obstacles and roll on the ground upon landing. The robot is equipped with two propellers that are periodically activated to jump, a soft cage that protects the robot from impacts and allows to passively roll on the ground, and a passive self-righting mechanism for repetitive jumps. The minimalistic control and design reduce the complexity of the mechanics and electronics and are instrumental to the production of a large number of robots. In the paper, the key design aspects of the robot are discussed, the locomotion of a single prototype is experimentally characterized, and improvements of the system for future swarm operations are discussed.

IEEE2018

Design Methodology for Engineering Multifunctional Mesoscale Robots

Zhenishbek Zhakypov

In this thesis our research goal is to develop, study and demonstrate multifunctional multi-robot systems in mesoscale. Particularly, our goal is to study and demonstrate terrestrial multi-locomotion and collective behaviours with mesoscale robots, similar to small-scale natural systems, by feeling the gap in the field. Our research objective is to develop, evaluate and demonstrate minimal, compact, variable power and efficient actuation mechanisms for multi-locomotion and rapid fabrication methods for robot multiplicity employing functional materials and composite design. In doing so, we intend to establish a comprehensive and systematic design methodology for designing multifunctional, mass-producible mesoscale robots for various applications. This dissertation first attempts to explore and answer the following key research question: how to achieve variable power, efficient and compact actuation in mesoscale? The relation between performance and physicality is significant for especially mesoscale robot design and is poorly studied. Our goal is to achieve high power, variable speed and high efficiency actuation in mesoscale. We attempt to address this by exploring unconventional active material-based actuation methods using shape memory alloy and composite material. In doing so, we quest of the following: what are the compromises should be made between force, speed, efficiency and size of functional material-based actuators? We investigate and demonstrate new, compact multimaterial actuators and mechanisms that possess power density superior to conventional motors, produce high speed and high force actuation and achieve multifunctionality when distributed and actuated selectively, all with minimal and compact forms and integrity. While we study and develop design methods at the component level, like actuation, based on performance and physical features, we look for the same at the composite level or robotic system level. The next research question we attempt to address is what, if any, is the general design methodology for constructing composite robots?. To address this we formulate and analyze robogami design in terms of mechanisms, geometry, functional components, materials and fabrication to highlight their relation, potential and the challenges, as well as to structure the knowledge in the field. This leads to a systematic design approach that consolidates these critical design features and facilitates robot design and fabrication process. To ensure applicability of our methodology, we analyze the design process of composite robots reported in the literature and design a multi-locomotion mesoscale robot, called Tribot, as a case study. We further investigate the application of the proposed actuation and rapid composite robot design methods by questing of how to achieve multifunctional multi-robot behaviors in mesoscale? We address this by constructing a unique, untethered, multi-locomotion robotic collective to study locomotion and cooperative behaviors. We investigate minimal, compact and tunable mechanisms that generate high power jumping and low power crawling locomotion. We overcome the key trade-off between the actuation power and weight and construct a 10 g palm-sized prototype, the smallest and lightest self-contained, multi-locomotion robot to date, by folding a quasi-2-D mechamatronic composite with locomotion mechanisms, smart actuation and sensing layers, enabling robot multiplicity assembly-free mass-production.

EPFL2019

Adaptive Morphology for Multi-Modal Locomotion

Ludovic Daler

There is a growing interest in using robots in dangerous environments, such as for exploration, search-and-rescue or monitoring applications, in order to reduce the risks for workers or rescuers and to improve their efficiency. Typically, flying robots offer the possibility to quickly explore large areas while ground robots can thoroughly search specific regions of interest. While existing robotic solutions are very promising, they are often limited to specific use cases or environments. This makes them impractical for most missions involving complex or unpredictable scenarios, such as search-and-rescue applications. This limitation comes from the fact that existing robots usually exploit only a single locomotion strategy, which limits their flexibility and adaptability to different environments. In this thesis, a multi-modal locomotion strategy is investigated as a way to increase the versatility of mobile robots. We explore integrated design approaches, where the same actuators and structure are used for different modes of locomotion, which allows a minimization of the weight and complexity of the robot. This strategy is challenging because a single locomotor system must accommodate the potentially conflicting dynamics of multiple modes of locomotion. Herein, we suggest taking inspiration from nature, in particular the common vampire bat \emph{Desmodus rotundus}. The goal being to make multiple modes of locomotion dynamically compatible (i.e. have compatible speeds and torques requirements), by optimizing the morphology of the locomotor system and even by adapting the morphology of the robot to a specific mode of locomotion. It is demonstrated in this thesis that the integrated design approach can be effectively implemented on a multi-modal aerial and terrestrial robot, and that two modes of locomotion can be made dynamically compatible by optimizing the morphology. Furthermore, an adaptive morphology is used to increase the efficiency of the different modes of locomotion. A locomotor system used both for walking on the ground and controlling flight, has been successfully implemented on a multi-modal robot, which further has deployable wings to increase its performances on the ground and in the air. By successfully exploiting the concepts of integrated design and adaptive morphology, this robot is capable of hovering, forward flight and ground locomotion. This robot demonstrates a very high versatility compared to state of the art of mobile robots, while having a low complexity.