Study of a novel amphibious water jet thruster for returnable jumping

In consideration of the poor load capacity and limited jumping performance of the existing aquatic bionic robots, an amphibious water jet thruster which can conduct effective jumping actions both in aquatic and terrestrial environments is under development for the amphibious jumping robot. This paper covers the structural design, working process analysis, theoretical modeling and experimental verification of jumping performance of the water jet thruster. The proposed water jet thruster adopts liquid nitrogen to accelerate propellant water stored in the water tank and generate enough reaction thrust, therefore realizing its returnable jumping (two sequential jumping movements). Then a simple and effective mathematical model is established to evaluate its two sequential jumping performances. Finally, the indoor experiments of thrust measurement are carried out to validate the reasonability of the theoretical model and the practicability of the water jet thruster.