The SOLERO Rover

SOLERO (Solar-powered Exploration Rover) is the name of a rover built in a study carried out jointly by the Swiss Federal Institute of Technology of Lausanne (EPFL), Switzerland, and von Hoerner & Sulger GmbH (vH&S), Germany, under a contract from the European Space Agency (ESA). The objective of this activity was to develop a system design for a regional exploration rover, including breadboarding for the demonstration of locomotion capabilities, payload accommodation, power provision and control. The most prominent feature of the SOLERO rover is its ability to operate relying on just-generated solar power, i.e., with minimal use of batteries (used only for contingency or peak power demands). A number of solar-powered vehicles operate in this mode on Earth. However, as Mars is farther from the sun than Earth, the power available from sunlight is significantly reduced and thus designing a working and reliable system is much more difficult. We have achieved power consumption optimization by combining smart power management and an efficient locomotion system. The calculations for power demand have been based on results obtained from ground testing of the breadboard rover and on accurate models of the Martian environment (i.e., reduced gravity, reduced intensity of sunlight, dust contamination on the solar arrays, temperatures, terrain surface, etc.). It was found that the rover should incorporate energy storage for peak demand and contingency situations only, allowing the solar array to be sized for smaller loads and resulting in a lighter, smaller and more reliable rover system. More information about the project can be found in [50, 16]. At the end of the project, one of the breadboards was significantly modified to serve as a research platform for autonomous navigation and enhanced control. The purpose of this chapter is to describe the mechanical design, the sensors and the control architecture of SOLERO.