Robotics Verification and Validation Strategies for Perseverance Rover Sampling and Caching

The Mars 2020 Sampling and Caching Subsystem (SCS) is the most complex robotic system ever fielded on a Mars Rover. It includes a 5 degree-of-freedom Robotic Arm, coring drill, gas Dust Removal Tool, interfaces for two turret-mounted instruments, and an Adaptive Caching Assembly (ACA). The ACA is itself a complex robotic system, containing hardware to support docking and bit exchange, a 3 degree-of-freedom Sample Handling Assembly for manipulating sample tubes, storage for several drill bits and sample tubes, and mechanisms to support observing and sealing samples collected by the drill. To successfully verify and validate the SCS hardware and software and its integration with the Mars 2020 flight system several key strategies were employed. The SCS Verification and Validation (V&V) program utilized multiple test venues with tiered levels of fidelity. These included simulation and visualization software environments, low fidelity development testbeds, testbeds with high fidelity SCS hardware and commercial off-the shelf avionics, integrated system testbeds with flight-like avionics, and environmental testbeds capable of simulating Martian surface temperature and pressure. Multiple units of each SCS hardware component moved fluidly between test venues to accomplish myriad standalone and coordinated test objectives. Test preparation and executions were performed by a diverse team of engineers with training and technical ownership tailored for individual experience and role. Despite significant differences between test venues, the SCS V&V team established efficient and consistent processes and tools for procedure development, test execution, and data review that enabled personnel, as well as technical products such as sequences and parameter configurations, to flow between venues effectively. A series of benchmark tests provided evidence of performance consistency as elements were transferred between venues and as system capability evolved. This paper provides an overview of the SCS V&V program and explores several overarching strategies that enabled successful operation in the face of unprecedented complexity. Key outcomes of the SCS validation effort are summarized, along with lessons learned and beneficial integrations of validation tool and process innovations into Mars surface operations.