  This paper presents a trade study analysis to design and evaluate the
perception system architecture for ReachBot. ReachBot is a novel robotic
concept that uses grippers at the end of deployable booms for navigation of
rough terrain such as walls of caves and lava tubes. Previous studies on
ReachBot have discussed the overall robot design, placement and number of
deployable booms, and gripper mechanism design; however, analysis of the
perception and sensing system remains underdeveloped. Because ReachBot can
extend and interact with terrain over long distances on the order of several
meters, a robust perception and sensing strategy is crucial to identify
grasping locations and enable fully autonomous operation. This trade study
focuses on developing the perception trade space and realizing such perception
capabilities for a physical prototype. This work includes analysis of: (1)
multiple-range sensing strategies for ReachBot, (2) sensor technologies for
subsurface climbing robotics, (3) criteria for sensor evaluation, (4) positions
and modalities of sensors on ReachBot, and (5) map representations of grasping
locations. From our analysis, we identify the overall perception strategy and
hardware configuration for a fully-instrumented case study mission to a Martian
lava tube, and identify specific sensors for a hardware prototype. The final
result of our trade study is a system design conducive to benchtop testing and
prototype hardware development.
