Poka: a necro-robot beetle with a measured payload ratio of 6847%

This paper is concerned with the design, manufacture and validation of Poka, a novel millimetre-scale necro-robot aimed at bridging the performance gap between miniature robots and insects. To create Poka, we use the exoskeleton of a deceased five-horned rhinoceros beetle (Eupatorus gracilicornis) as a mechanical chassis, which is mechatronically functionalised to enable ambulation. When comparing the payload ratio, PR, of Poka against reported values of the rhinoceros beetle Xyloryctes thestalus, we find that Pokas PR is more than 2-fold higher, reaching a measured maximum of 6847% (i.e. 68.47 times its own body weight). The specific power at maximum payload, Ps,t, is nevertheless of the same order of magnitude in both Xyloryctes thestalus (0.21 W/kg) and Poka (0.28 W/kg). Pokas highest average speed, [Formula] is achieved at a PR = 2739%, after which it progressively decreases with increasing payload ratio, reaching its minimum [Formula] at maximum payload ratio. When comparing Pokas maximum measured PR of 6847% against those of sixteen other ambulating robots, we find that Pokas PR far exceeds that of any other robot to date, the highest being otherwise from SuperBot who has a PR = 530%. Pokas payload ratio is therefore the highest robot payload ratio recorded to date and we attribute this to (a) the use of the beetle body as a natural composite chassis with high specific properties, and (b) the additive manufacture of bionic beetle parts using low density but stiff polylactic acid, designed with structurally stable geometries.