The creation of autonomous subgram microrobots capable of complex behaviors remains a grand challenge in robotics largely due to the lack of microactuators with high work densities and capable of using power sources with specific energies comparable to that of animal fat (38 megajoules per kilogram). Presently, the vast majority of microrobots are driven by electrically powered actuators; consequently, because of the low specific energies of batteries at small scales (below 1.8 megajoules per kilogram), almost all the subgram mobile robots capable of sustained operation remain tethered to external power sources through cables or electromagnetic fields. Here, we present RoBeetle, an 88-milligram insect-sized autonomous crawling robot powered by the catalytic combustion of methanol, a fuel with high specific energy (20 megajoules per kilogram). The design and physical realization of RoBeetle is the result of combining the notion of controllable NiTi-Pt–based catalytic artificial micromuscle with that of integrated millimeter-scale mechanical control mechanism (MCM). Through tethered experiments on several robotic prototypes and system characterization of the thermomechanical properties of their driving artificial muscles, we obtained the design parameters for the MCM that enabled RoBeetle to achieve autonomous crawling. To evaluate the functionality and performance of the robot, we conducted a series of locomotion tests: crawling under two different atmospheric conditions and on surfaces with different levels of roughness, climbing of inclines with different slopes, transportation of payloads, and outdoor locomotion.
We introduce Bee + , a 95-mg four-winged microrobot with improved controllability and open-loop-response characteristics with respect to those exhibited by state-of-the-art twowinged microrobots with the same size and similar weight (i.e., the 75-mg Harvard RoboBee). The key innovation that made possible the development of Bee + is the introduction of an extremely light (28-mg) pair of twinned unimorph actuators, which enabled the design of a new microrobotic mechanism that flaps four wings independently. A first main advantage of the proposed design, compared to those of two-winged flyers, is that by increasing the number of actuators from two to four, the number of direct control inputs increases from three to four when simple sinusoidal excitations are employed. A second advantage of Bee + is that its four-wing configuration and flapping mode naturally damp the rotational disturbances that commonly affect the yaw degree of freedom of two-winged microrobots. In addition, the proposed design greatly reduces the complexity of the associated fabrication process compared to those of other microrobots, as the unimorph actuators are fairly easy to build. Lastly, we hypothesize that given the relatively low wing-loading affecting their flapping mechanisms, the life expectancy of Bee + s must be considerably higher than those of the two-winged counterparts. The functionality and basic capabilities of the robot are demonstrated through a set of simple control experiments.Index Terms-Micro/nano robots, automation at micro-nano scales, aerial systems: mechanics and control.
We discuss the problem of designing and implementing controllers for insect-scale flapping-wing micro air vehicles (FWMAVs), from a unifying perspective and employing two different experimental platforms; namely, a Harvard RoboBee-like two-winged robot and the four-winged USC Bee + . Through experiments, we demonstrate that a method that employs quaternion coordinates for attitude control, developed to control quadrotors, can be applied to drive both robotic insects considered in this work. The proposed notion that a generic strategy can be used to control several types of artificial insects with some common characteristics was preliminarily tested and validated using a set of experiments, which include position-and attitude-controlled flights. We believe that the presented results are interesting and valuable from both the research and educational perspectives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.