"Recent mobility challenges led NASA Johnson Space Center to develop a prototype robotic lunar rover Resource Prospector 15 (RP15) capable of wheeled, legged, and crawling behavior. To systematically understand the terradynamic performance of such a device, we developed a scaled-down rover robot and studied its locomotion on slopes of dry and wet granular media," wrote the researchers in their paper.
The researchers explained how planetary rovers face difficulties in soft soil during extraterrestrial exploration. One such example is NASA’s Mars Exploration Rover Spirit that became entrapped due to excessive sinkage in the low cohesion sulfate sands of Troy near the Gusev crater.
This resulted in the end of its mobility. The researchers found a potential solution to these complications.
"Addition of a cyclic-legged gait to the robot’s wheel spinning action changes the robot dynamics from that of a wheeled vehicle to a locomotor paddling through frictional fluid, " wrote the researchers.
In addition, "a peculiar gait strategy that agitates and cyclically reflows grains under the robot allows it to “swim” up loosely consolidated hills. Whereas substrate disturbance typically hinders locomotion in granular media, the multimode design of RP15 and a diversity of possible gaits facilitate formation of self-organized localized frictional fluids that enable effective robust transport," continued the researchers.
The end result is that RP15 can traverse loose soil better than any of its predecessors or competitors. This is crucial as "loose soil known as regolith covers large expanses of both lunar and Martian terrain."
As far as we can see, RP15 looks like an adorable rover that has the power to keep going in tough conditions. We wish NASA luck with its future rovers and projects in space.