Planning and Control for Autonomous Drives of the Mars Sample Recovery Helicopter

The Mars Sample Return (MSR) campaign is humanity’s first attempt at returning samples from the Martian surface to Earth. This campaign is composed of multiple spacecraft, landers and robotic systems that collaborate to collect, retrieve, and ultimately return a diverse set of Martian rock and regolith samples. The Sample Recovery Helicopter (SRH) is a team of hybrid aerial-ground robots designed as a backup system to transport sample tubes from the surface of Mars to the Sample Retrieval Lander (SRL) for transport to Earth. An SRH robot is required to perform accurate drives from helipads to sample tube pick up or drop off locations and to handle sample tubes with a manipulator arm. The mobility system has a four wheel skid-steer configuration with 10cm diameter wheels, a maximum rock-height traversal capability of 5.0cm, and a total mass of less than 150g. This paper presents the system-level design of the autonomy system for driving SRH during surface operations. A prototype platform is used to quantitatively evaluate a motion planning and control strategy to position the robot above a desired pose in preparation for sample-tube pick ups. Results demonstrate that this autonomous system is capable of driving the skid-steer platform to within the required sample tube to end-effector pose error of ±2cm in x, ±4cm in y, and ±5° in yaw.