Design and analysis of a sun sensor for planetary rover absolute heading detection

This paper describes a new sun sensor for absolute heading detection developed for the Field Integrated, Design and Operations (FIDO) rover. The FIDO rover is an advanced technology rover that is a terrestrial prototype of the rovers NASA/Jet Propulsion Laboratory (JPL) plans to send to Mars in 2003. Our goal was to develop a sun sensor that fills the current cost/performance gap, uses the power of subpixel interpolation, makes use of current hardware on the rover, and demands very little computational overhead. The need for a sun sensor on planetary rovers lies in the fact that current means of estimating the heading of planetary rovers involves integration of noisy rotational-speed measurements. This noise causes error to accumulate and grow rapidly. Moreover, the heading error affects the estimate of the x and y position of the rover. More importantly, incremental odometry heading estimation is only reliable over relatively short distances. There is an urgent need to develop a new heading-detection sensor for long traverses [for example, 100 in per Sol (Martian Day)], as requested for future Mars mission. Results of a recent FIDO field trial at Black Rock Summit in Central Nevada and several operations readiness tests at the JPL MarsYard using the sun sensor have demonstrated threefold to fourfold improvement in the heading estimation of the rover compared to incremental odometry.