Visual Odometry Thinking While Driving for the Curiosity Mars Rover's Three-Year Test Campaign: Impact of Evolving Constraints on Verification and Validation

Over the first 9 years of the Mars Science Laboratory (MSL) Curiosity rover's surface mission, more than 87% of its driving was performed using Visual Odometry (VO). The benefits of using VO during driving are that it minimizes rover position uncertainty and can be used to monitor wheel slip, halting a drive if excessive wheel slip is occurring. The VO implementation onboard Curiosity acquires and processes VO images in between drive steps while the rover is stationary. A VO Thinking While Driving (VTWD) flight software capability has been developed to enable the processing of VO images during rover driving, increasing the distance Curiosity can drive using VO during a given time period up to as much as 1.75x total distance. Verification and Validation (V&V) of this capability has been challenging due to impacts from the COVID-19 pandemic and unavailability of the JPL Mars Yard outdoor test site. The VTWD V&Vtest procedures were modified to use a small indoor space with Mars-like terrain. This paper describes the 3 year V&V effort under challenging conditions to approve the VTWD capability for use on the Curiosity rover.