Testing the effect of scaling on microrobot locomotion performance

The effects of scaling on locomotion performance has fascinated biologists, physicists and engineers alike. In particular, roboticists have exploited dynamic scaling to build systems at sizes varying from a tens of centimeters to several meters. Thanks to recent advances in manufacturing, insect-scale robotics is currently an exciting research direction and holds the promise of tremendous impact in areas of search-and-rescue and high-value asset inspection. However, most robots at this scale have simplified morphology and can only demonstrate basic mobility. Here, we present the newly designed HAMR-Jr, a 22.5mm, 320mg quadrupedal microrobot. With eight independently actuated degrees of freedom, HAMR-Jr is, to our knowledge, the most mechanically dexterous legged robot at its scale and is capable of high-speed locomotion (13.91 bodylengths/s) at a variety of stride frequency (1-200Hz) using multiple gaits. We achieved this using a design and fabrication process that is flexible, allowing us to exploit and implement the physics of scaling with minimum changes to our workflow. We further characterized HAMR-Jr’s open-loop locomotion and compared it with the larger scale HAMR-VI microrobot to demonstrate the effectiveness of scaling laws in predicting running performance.