Design, Prototype, and Performance Assessment of an Autonomous Manipulation System for Mars Sample Recovery Helicopter

This paper presents the design, prototype, and testing of a 150 g (current best estimate) manipulation system that enables Mars Sample Recovery Helicopter (SRH) concept to autonomously pickup, stow, and drop-off Returnable Sample Tube and Glove Assemblies (RGAs) on the surface of Mars next to the Sample Retrieval Lander (SRL). It consists of a 3 DOF planar Robotic Arm (RA), a novel 2 DOF Gripper with compliant fingers, and a Stow Mechanism. Within the planned Mars Sample Return (MSR) campaign, two SRHs would operate in parallel to retrieve and transfer total of 10 RGAs (146g each) to the SRL, as the backup to the Perseverance Rover. Once SRH arrives at the target pickup location, the RA places the Gripper precisely over the RGA. The gripper grabs and picks up RGAs using a linkage based non-back-drivable mechanism and its compliant fingers. Subsequently, the RA is secured into the stow features, following dislodging rocks and pebbles, by going through a specific sequence of joint trajectories. This ensures the RA and RGA are stable and secure during transit to the SRL while all Manipulation System actuators are powered off. The whole sequence of manipulation is performed autonomously using feedback of a pair of stereo-cameras and absolute encoders. Experimental evaluation of the Manipulation System performance has proved its robustness and consistency in successful RGA pickup, stow, and drop-off.