NASA have made a new ‘mini’ Mars rover that will be able to climb hills even if they’re covered in sand and gravel – new robot for future exploration missions.
After the successful Curiosity mission and the data collected by the mission, it is clear that exploring planetary surfaces like Mars or the moon can encounter soft, loose and steep soils, the perfect ingredients for getting stuck.
Hence the newly developed “Mini Rover,” is designed in such a way that it can easily move on such type of surfaces. The model is scaled down by 3D-printer. Also built and tested by researchers at the Georgia Institute of Technology. You can read full paper published in the journal Science Robotics.
Back in 2009, when NASA’s Spirit rover became stuck in soft soil on Mars and couldn’t be moved. It was used as a stationary science platform for three months until the rover stopped communicating in March 2010. The mission was officially concluded by NASA in 2011.
At that time engineers felt the requirement of such robot which can easily move on those surfaces. The soft granular soil, which is known as regolith, acts almost like a fluid when it’s been disturbed on Mars, meaning it’s easier to get stuck in it. The moon too has similar soil.
After the loss of Spirit, engineers at NASA’s Johnson Space Center in Houston built the Resource Prospector mission rover, or RP15 rover.
The concept involved a rover that allowed for wheel spinning combined with a lifting and sweeping motion by the rover’s legs. But the mission itself was canceled in 2018.
Supported by the NASA National Robotics Initiative and the Army Research Office, researchers at Georgia Tech proposed building and testing a miniature version of the rover made from 3D-printed plastic. They named this small-scale RP15 the Mini Rover.
“Our broad design goal was to replicate RP-15 drive functionality on a scaled-down robot that we could operate in our instrumented test bed,” said Siddharth Shrivastava, study author and an undergraduate student in Georgia Tech’s George W. Woodruff School of Mechanical Engineering, to the news agency CNN.
Although the robot isn’t an exact replica of the larger rover, which has motors encapsulated in its wheel diameter and a larger power-to-weight ratio, the Georgia Tech team was able to replicate the lifting, sweeping and wheel-spin motions. These motions were key for their tests. Their model, built using in-house 3D printers, has four wheeled legs that are powered by 12 motors.
Once the robot was assembled at Georgia Tech, it was time to test the Mini Rover on flat and sloped beds of poppy seeds. While they aren’t exactly an analog of the surfaces these rovers might encounter on other planets, the 1 millimeter seeds have a number of features that make them suitable for experiments.
The researchers started by putting Mini Rover through the same gait motion tests that RP15 experienced at Johnson Space Center and also explored ranges of motion that only the smaller rover could perform due to its diminutive size.
If only the wheels were activated, the robot would slip over the poppy seeds and sink down. When the sweeping motion of the robot’s legs was added, the Mini Rover was able to use this unique locomotion method to paddle out of the poppy seeds as they shifted unpredictably. This prevented the rover from sinking more by creating seed mounds to its advantage that it could climb over.
This wheeled, sweeping and lifting motion created a successful crawling motion for the rover, even when one of its limbs was intentionally disabled. This crawl was dubbed “rear rotator pedaling” by the researchers.
The mini rover has enough degrees of freedom that it can get out of jams pretty effectively.
The rover could successfully climb the hill when its front wheels stirred up the poppy seeds and pushed them back to its rear wheels, and the rear wheels wiggled in a side-to-side paddling motion. This created a smaller slope for the rear wheels to climb.
Overall, the mini rover was able to continue up the hill. But a robot with only spinning wheel motion would have become stuck.
These tests were also carried out at Johnson Space Center with the full-size RP15 rover driving over a flat, moist sand bed, and they achieved the same results that were found with Mini Rover.
Mars 2020 rover is officially named ‘Perseverance’
Going forward, the engineers want to test the larger RP15 and Mini Rover on steeper slopes using different soils and terrains to test more functionality. They also want to add local terrain sensing, which could help the rover detect its surroundings. Shrivastava is also curious to explore downhill locomotion.
The capabilities demonstrated in the study could be used to inform the design of next-generation rovers that could visit previously unexplored areas like the lunar poles, or even challenging spots on Earth, the researchers said.