The Spinning Projectile Extreme Environment Robot

Abstract

The Spinning Projectile Extreme Environment Robot is a disposable soft landing projectile geared towards the exploration of Lunar and Martian skylights, cave entrances with large vertical drops. Robot size and hardware simplicity are emphasized above all else during design. The robot spins up along two axes and is fired from a cannon, recording video during its flight. Two-axis spin stabilization greatly reduces the size and complexity of the robot. Just before impact, the robot ignites a solid-fuel rocket motor to safely land. We investigate the dynamics and stability of the robot, both in the analytical and numerical sense. We also present novel methods for visual state estimation of a rapidly spinning object. This allows incoherent video taken by the spinning robot to be constructed into a usable format for analysis. We evaluate our methods using a simulated exploration of the Mare Tranquillitatis Lunar pit. We build the robot and test it experimentally to validate the dynamics and visual state estimation. We validate the dynamics with a live-fire drop and soft landing test. We drop the robot from a height of 5.05m with the descent motor firing after a predetermined delay. Results indicate that the impact velocity is greatly reduced. Next, we spin the robot in multiple environments and record video to evaluate our visual state estimator. We provide measurements of direction and magnitude against ground truth, and use the state estimate to stitch together human-comprehensible panoramas of each scene.