Testing of planetary rover wheels

All robotic rovers for planetary exploration and the vehicles used to carry astronauts on the surface of the Moon used wheels as running gear. The same applies to the majority of projects for future exploration missions, both for the unmanned and manned rovers. Dynamic modeling of wheeled vehicles is a common practice in automotive technology, and commercial codes are usually employed. Such dynamic modeling however requires the knowledge of the wheel-terrain interaction that is usually beyond that available for the specific type of wheels designed for planetary rovers, in particular when they operate on regolith like in the actual working conditions. Test campaigns aimed at characterizing the behavior of the specific non pneumatic, elastic but sometimes rigid, wheels are required. They must be performed on the wheels designed for planetary rovers operating on specific soils simulating the terrain (the so-called planetary simulant) which can be found in the actual applications. A test rig that can be used to characterize the wheel-ground interaction under different operating conditions is here described and some tests aimed at characterizing its operation are reported.