A Screw-Driven Robot Could Autonomously Mine Rocky Worlds

Navigating the harsh terrain of other rocky worlds has consistently been challenging. The Free Spirit campaign unfortunately failed in its goal to will the plucky Martian rover out of the morass it found itself in, despite two years of continual effort from some of the world’s best engineers. To combat this difficulty, other engineers have turned to alternative propulsion methods, and a team of researchers in the EU have done just that for their work on an autonomous mining robot. They decided to use an Archimedes screw as their primary propulsion method.

The team has already successfully tested various prototype iterations of their miniaturized mining robot. More recently have released a paper that detailed a mobility platform based on four individually controlled Archimedes screws that could be useful for more than just mining underground.

As with most engineering projects, they started with a computer model, which resulted in a CAD model that the team tested on different terrain. They weren’t the first ones to think of using an Archimedes screw as a driving mechanism. Existing research has pointed out that it is not the most efficient on some terrains. However, it can navigate almost all terrains to at least some degree.

Kinematics models are critical to the development of any robot, and one with a relatively obscure propulsion system is no exception. Since Archimedes screws can be modeled from any observational angle, coordinating the operation of each of the four independent screws to align correctly to the desired direction required some complex modeling that was eventually hosted as part of the control algorithm on board a computer seated on top of the mobile platform.

Another part of the control algorithm required the robot to understand how it was orientated, and to do that, the team developed an integrated network of sensors. These ranged from time of flight positioning systems, which allowed the robot to gauge the distance to an object, to force sensors on the screws themselves that would ensure they wouldn’t over-torque and burn out their drive motors.

Once the sensors were selected and the preliminary control code was written, it was time to put it to a real environmental test. The team built a physical prototype, partly out of 3D-printed parts, and set about moving it about on various surfaces. The drive system worked well on snow, sand, frozen ground, and mud. However, it was mainly used to traverse level surfaces rather than the more complicated slopes that it might encounter in some environments, such as Mars. 

That is not to say the system cannot adapt to slopes – just that there is more work to be done. ROBOMINERS, the EU project focused on building an autonomous mining robot, is looking to complete its final prototype soon, and the results of the drive platform testing shown in this latest paper will help contribute to that. Someday, it might contribute to a similar robot on the moon or Mars.

Learn More:
Gkliva et al – A Multi-Terrain Robot Prototype With Archimedean Screw Actuators: Design, Realization, Modeling, and Control
UT – NASA Tests a Robotic Snake That Could Explore Other Worlds
UT – Snake Rovers Might be the Best Way to Explore the Surface and Tunnels on Mars
UT – NASA Redoubling Efforts to Contact Spirit

Lead Image:
Prototype of the screw-driven robot on leafy ground.
Credit – Gkliva et al.