Lunar Surface Manipulation System

Assemblers are a team of modular robots that work together to build things. Each Assembler is a stack of one or more Stewart platforms, or hexapods, made up of two plates connected by six linear actuators for movement, enabling a full six-degree-of-freedom (DOF) pose of the top plate relative to the bottom plate (see figure to the right). An end effector on each Assembler enables gripping, lifting, and welding/joining. The Assemblers system architecture features novel control algorithms and software, sensors, and communicator technology that coordinate operations of Assembler teams. The control system includes an important module for task management that estimates how many robots are needed, the optimal number of hexapods in each Assembler, and the estimated voltage needed. There are also modules for trajectory generation, joint control, sensor fusion, and fault detection. The novel control system directs the Assembler operations for high accuracy and precision, yet there is built-in dynamic resilience to failure. For example, if a single hexapod on an Assembler fails, the system deems it “rigid” in its last pose and redistributes the work to the other Assemblers. The image below shows a storyboard of operations for how Assemblers might build a solar array. NASA has developed a hardware demo with communications between subsystems, backed up by detailed simulations of the kinematics and actuator dynamics.

The androgynous fastener is lightweight and facilitates assembly through simple actuation with large driver-positioning tolerance requirements. This fastener provides a high-strength, reversible mechanical connection and may be used in high strength-to-weight ratio structural systems, such as lattice structure systems. The androgynous fastener resists tensile and shear forces upon loading of the lattice structure system thereby ensuring that the struts of the lattice structure system govern the mechanical behavior of the system. The androgynous fastener eliminates building-block orientation requirements and allows assembly in all orthogonal build directions. This androgynous fastener may be captive in building-block structural elements thereby minimizing the logistical complexity of transporting additional fasteners. Integration of a plurality of the androgynous fasteners into a high performance, robotically managed, structural system reduces launch energy requirements, enables higher mission adaptivity and decreases system life-cycle costs. The androgynous fastener is beneficial in any application where robotic end effectors are used to join structural components (or other parts) together. It may be particularly desirable for applications requiring frequent movement of hardware to an assembly site to replace joint connections.

This NASA-developed eVTOL UAS is a purpose-built, electric, reusable aircraft with rotor/propeller thrust only, designed to fly trajectories with high similarity to those flown by lunar landers. The vehicle has the unique capability to transition into wing borne flight to simulate the cross-range, horizontal approaches of lunar landers. During transition to wing borne flight, the initial transition favors a traditional airplane configuration with the propellers in the front and smaller surfaces in the rear, allowing the vehicle to reach high speeds. However, after achieving wing borne flight, the vehicle can transition to wing borne flight in the opposite (canard) direction. During this mode of operation, the vehicle is controllable, and the propellers can be powered or unpowered. This NASA invention also has the capability to decelerate rapidly during the descent phase (also to simulate lunar lander trajectories). Such rapid deceleration will be required to reduce vehicle velocity in order to turn propellers back on without stalling the blades or catching the propeller vortex. The UAS also has the option of using variable pitch blades which can contribute to the overall controllability of the aircraft and reduce the likelihood of stalling the blades during the deceleration phase. In addition to testing EDL sensors and precision landing payloads, NASA’s innovative eVTOL UAS could be used in applications where fast, precise, and stealthy delivery of payloads to specific ground locations is required, including military applications. This concept of operations could entail deploying the UAS from a larger aircraft.

The Soft Mate lifting device is a below-the-hook tool that provides initial and gentle contact between mating connections while using a crane. The device utilizes a set of rolling lobe airbags to add a pneumatically adjustable soft spring into the lift rigging of a crane. The device is particularly useful for NASA's testing of the SLS, which requires the assembly and disassembly of hundreds of threaded load lines. While the load lines have relatively large diameter threaded connections to join components, the fine threads can be easily damaged by impact or misalignment. The added softness of the Soft Mate's airbag system helps maintain a neutral load on the threads to prevent galling as they are manually screwed or unscrewed. The current state of the art in precision placement of objects by cranes is a below-the-hook hydraulic system that does not add any elasticity in the lift rigging and requires the user to constantly adjust the hydraulic pressure to maintain a neutral force on objects being joined. By virtue of the pneumatic core, the Soft Mate lifting device provides the needed elasticity while minimizing user interaction during lifting and placement. Although designed particularly to aid in NASA's SLS threaded load line assembly, the extra compliance provided by the Soft Mate system may also benefit other applications where additional control and precision are required for placing or mating heavy components. The Soft Mate design has undergone extensive stress analysis and is based on commercially available components that can be scaled and optimized for different weight requirements. The system provides the flexibility needed to assemble heavy components with threaded connections or other precision crane placement applications where greater compliance is needed.

The Gripper is located at the end of a robotic system consisting of a robotic arm equipped with a Tool Drive or End Effector comprising the input actuator to the Gripper as well as the structural, power and data link between the Gripper and the robotic arm. In a notional concept of operations, a Servicer would approach the Client in an autonomous rendezvous and capture (AR&C) maneuver. When the Servicers sensor suite confirms that the distance, orientation, and relative translational and angular rates with respect to the Client are within an acceptable range, the Servicer enables the grasping sequence, where the robotic arm, equipped with Gripper, extend forward to the Client. When the Gripper/ Servicer sensors indicate that the Client marman ring is sufficiently within the capture range of the Gripper, a trigger signal is sent to the robot control system that commands the End Effector to drive the mechanism of the Gripper and affect closure around the marman ring. The Gripper consists of a pair of jaws which are driven by an internal transmission. The transmission receives input torque from the End Effector and converts the torque to appropriate motion of the jaws.