Toward Autonomy in Sub-Gram Terrestrial Robots

Research toward small, autonomous, and mobile robots is inspired by both the insects we see around us and numerous applications, from inspection of jet engines and civil infrastructure to medical procedures. When comparing existing robots at small scales with their biological counterparts, the capability for autonomous operation is a glaring contrast. This review describes the state of the art in robotics at sub-gram scales along with the progress toward autonomy in power, mobility, and control at these small sizes. Metrics are described to both quantify the performance of existing sub-gram robots (e.g., speed and cost of transport) and define a more quantitative path toward autonomy (e.g., mass-specific run time and traversal probability). These metrics from existing robots are also compared with those of insects to identify significant performance gaps and highlight important areas for future study.