Localization of the Perseverance Rover at the Van Zyl Overlook Region by using Visual Odometry

Landed at the Jezero Crater in February 2021, the NASA Mars 2020 Perseverance rover is now operating across the ancient river delta, setting multiple records on the distance travelled in a single Martian day. The enhanced rover's navigation capabilities are enabled by the onboard dedicated hardware to carry out demanding computer vision tasks for an accurate localization and a safe path planning. Thanks to the augmented computational resources, the visual inputs from the onboard cameras are processed in real-time to replan the rover's trajectory without a stop-and-go approach.

To expand the scientific return of future robotic missions, we are developing a semi-autonomous Guidance, Navigation and Control (GNC) system that enables safe rover operations on unprepared terrains. To assess the accuracies of our localization software, based on established Visual Odometry (VO) techniques, we analyzed sequences of stereo images acquired by Perseverance's navigation cameras (NavCams). We retrieved an independent reconstruction of the rover's trajectory across the Van Zyl Overlook region (sols 65-72). We present here the methods we employed to process the high-resolution NavCams images by using a 3D-to-3D VO framework that accounts for an accurate modeling of the camera optics. Our VO-based estimates of Perseverance's attitude are consistent with the orientation provided by the onboard Inertial Measurements Units (IMU) data. The discrepancies between the reconstructed and the telemetered rover's locations suggest errors in the onboard wheel odometry measurements, which are mitigated by our VO-based estimate.