This paper proposes the utilization of Supernumerary Robotic Limbs (SuperLimbs) for augmenting astronauts during an Extra-Vehicular Activity (EVA) in a partial-gravity environment. We investigate the effectiveness of SuperLimbs in assisting astronauts to their feet following a fall. Based on preliminary observations from a pilot human study, we categorized post-fall recoveries into a sequence of statically stable poses called "waypoints". The paths between the waypoints can be modeled with a simplified kinetic motion applied about a specific point on the body. Following the characterization of post-fall recoveries, we designed a task-space impedance control with high damping and low stiffness, where the SuperLimbs provide an astronaut with assistance in post-fall recovery while keeping the human-in-the-loop scheme. In order to validate this control scheme, a full-scale wearable analog space suit was constructed and tested with a SuperLimbs prototype. Results from the experimentation found that without assistance, astronauts would impulsively exert themselves to perform a post-fall recovery, which resulted in high energy consumption and instabilities maintaining an upright posture, concurring with prior NASA studies. When the SuperLimbs provided assistance, the astronaut’s energy consumption and deviation in their tracking as they performed a post-fall recovery was reduced considerably.

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.

The discovery of ocean worlds such as Enceladus, Titan, and Europa motivates the development of versatile autonomous mobility systems to enable the next era of space exploration where there is large uncertainty in terrain specifications due to a lack of prior surface reconnaissance missions. To explore these environments, we propose Exobiology Extant Life Surveyor (EELS): the first large-scale (4 lm long with 400 Nm peak torque) snake robot. The large scale is achieved by using a screw-based active skin mechanism to decouple motion and shape control. Autonomous mobility for such a system remains an open problem due to its many Degrees of Freedom (DoFs), complex terrain interactions, and intermittent localization failures in GPS-denied perceptually degraded environments due to the presence of fog, dust, featureless terrains, etc. We propose NEO, an autonomy architecture that scales to large DoFs to generate a versatile set of gaits to achieve mobility in unknown extreme environments. We also discuss the resilience capabilities of NEO that achieves closed-loop tracking performance by leveraging exteroception when available but can also operate with proprioception only, leading to resiliency against localization failures via graceful degradation in performance rather than unsafe behaviors. A quantitative hardware evaluation of exteroceptive leader-follower gait is performed indoors on synthetic ice along with qualitative results of field deployment of the proprioceptive leader-follower and sidewinding gaits in extreme environments of icy and sandy terrains with mobility-stressing elements such as trenches, undulations, and steep slopes (up to 35 degrees). We present a set of lessons learned from field deployments with a summary of challenges and open research problems. Video: www.rohanthakker.in/eels-neo-autonomy.html

This paper presents the design and performance of a new locomotion strategy for serpentine robots using screw propulsion. The ARCSnake robot comprises serially linked, identical modules, each incorporating an Archimedes' screw for propulsion and a universal joint (U-Joint) for orientation control. When serially chained, these modules form a versatile serpentine robot platform which enables the robot to reshape its body configuration for varying environments, typical of a snake. Furthermore, the Archimedes' screws allow for novel omni-wheel drive-like motions by speed controlling their screw threads. This paper considers the mechanical and electrical design, as well as the software architecture for realizing a fully integrated system. The system includes 3N actuators for N segments, each controlled using a BeagleBone Black with a customized power-electronics cape, a 9 Degrees of Freedom (DoF) Inertial Measurement Unit (IMU), and a scalable communication channel over ROS. This robot serves as the first proof-of-concept demonstration of the NASA-JPL Exobiology Extant Life Surveyor (EELS) program that aims to deliver scientific instrumentation deep within the plume vents, caves, and ice sheets of Enceladus and Europa in search for extant lifeforms*.

This paper presents a novel manufacturing paradigm for constructing origami-inspired pop-up robots for future space exploration missions. The new approach uses a textile-enhanced rigid-flex printed circuit board (PCB) to implement a folding robot chassis using robust, spaceflight-tolerant materials, and integrates the robot electronics directly into the chassis for added compactness. The new approach also decouples the mechanical and electrical functions of the chassis flexures for improved kinematics and lifetime. This manufacturing paradigm was used to build PUFFER (Pop-Up Flat Folding Explorer Robot), a self-actuated pop-up rover being developed to provide a low-payload-cost mobility enhancement for future NASA missions.