“…An alternative method to prolong a given vehicle's endurance is to harvest ambient environmental resources, such as solar energy, to act as a supplemental power supply. Recent work in developing long-duration solar-powered UGVs (Heng et al (2011); Sulaiman et al (2013); Lever et al (2006)) which utilize the energy from the environment and charge storage batteries as backups for sustained operation has shown promise. For example, the Mars Opportunity Rover, which persistently explores unknown areas on Mars, has been working for a number of years using only solar power.…”