Mechanical & Fluid Systems

A Method for Accurate Load/Position Control of Rigidly Coupled Electromechanical Actuators

NASA has developed a technique designed to prevent cross-coupling in systems where two or more linear electro-mechanical actuators (EMA) are rigidly connected and are in danger of becoming cross-coupled. In such systems where the linked EMAs are commanded to achieve two distinct goals, such as position and load control, control problems often arise — especially at higher load and linear velocity levels. Both position and load control become inaccurate and in certain situations, stability of the overall system may be compromised. The NASA-developed approach mitigates the problem and achieves both accurate position following and desired load levels between the two (or more) actuators.

Posted in: Briefs, Mechanical Components, Mechanics, Positioning Equipment, Electronic control systems, Electronic equipment, Sensors and actuators


Ultralight Self-Deployable Solar Sails

This technology could be applied to self-deployable shelters, camping tents, sunshades, and house construction.Deployment of large structures such as solar sails relies typically upon electromechanical mechanisms, mechanically expandable or inflatable booms, launch restraints, controls, and other mechanisms that drastically increase the total mass, stowage volume, and areal density. The primary performance parameter for solar sails is areal density, which determines the acceleration of the sail. Present technology allows the solar sail areal density to be around 20 g/m2, and that permits only nearby demonstration missions.

Posted in: Briefs, Mechanical Components, Mechanics, Sun and solar, Packaging, Lightweighting, Spacecraft


Ultra-Compact Heat Rejection System

Radiator panels are the baseline heat rejection approach for most space systems. This approach is sound, but requires a large amount of surface area to radiate the anticipated heat load. The large panels require support structures to hold them in place and prevent damage. These structures impact mass and cost. Additionally, it is not practical to launch, transport, integrate, and relocate large panels as monolithic units. For this reason, a foldable scissor assembly is envisioned to stow the panels compactly and extend them before system startup. The moving parts and flexible fluid connections required for this approach add complexity and potential failure modes to the system. Some mission plans also require power system mobility for exploration well beyond the base camp. For this scenario, the radiator assemblies must be retracted, stowed, and redeployed each time the system is moved. These activities require time and effort, and they expose the radiator panels and associated mechanisms to damage risk. Even when properly stowed, the relatively thin panels could be damaged during transportation.

Posted in: Briefs, Mechanical Components, Mechanics, Thermal management, Packaging, Radiators, Spacecraft


Transformable and Reconfigurable Entry, Descent, and Landing Systems and Methods

The Adaptable, Deployable Entry Placement Technology (ADEPT) concept is a mechanically deployable, semi-rigid aeroshell entry system capable of achieving low ballistic coefficient during entry for planetary or Earth return missions. The decelerator system offers a lighter-weight solution to current rigid, high-ballistic-coefficient aeroshells and enables missions that are currently not feasible with rigid aeroshell construct.

Posted in: Briefs, Mechanical Components, Mechanics, Body panels, Entry, descent, and landing, Lightweighting


Self-Latching Piezocomposite Actuator

Langley Research Center, Hampton, Virginia NASA’s Langley Research Center has developed a self-latching piezocomposite actuator. The self-latching nature of this invention allows for piezo actuators that do not require constant power draw. Among other applications, the invention is well suited for use in aerodynamic control surfaces and engine inlets. The technology is a self-latching piezoelectric actuator with power-off, set-and-hold capability. Integrated into an aerodynamic control surface or engine inlet, the self-latching piezocomposite actuator may function as a trim tab, variable camber airfoil, vortex generator, or winglet with adjustable shapes. Deflections could be made in-flight, and set and maintained (latched) without a constant power draw. Current piezo actuators require constant power to control and manage their electric fields. The control device leverages the shape memory behavior (specifically, the remnant stress-strain behavior) to create a morphing actuator that changes and holds the new shape with no applied control signal.

Posted in: Briefs, Mechanical Components, Automation, Airframes, Electronic control units, Sensors and actuators


Active Response Gravity Offload and Method

The technology has commercial possibilities wherever individuals have to interact with heavy objects within a confined volume. Lyndon B. Johnson Space Center, Houston, Texas To train astronauts to live and work in the weightless environment on the International Space Station, NASA employs a number of techniques and facilities that simulate microgravity. Engineers at the NASA Johnson Space Center (JSC) have developed a new system called the Active Response Gravity Offload System (ARGOS) that provides a simulated reduced gravity environment within a confined interior volume for astronauts to move about and/or equipment to be moved about as if they were in a different gravity field. Each astronaut/item is connected to an overhead crane system that senses their actions (walking or jumping, for example) and then lifts, moves, and descends them as if they had performed the action in a specified reduced gravity.

Posted in: Briefs, Mechanical Components, Automation, Education, Education and training, Automation, Test facilities


Fluid Harmonic Absorber

These devices can be used in multistory buildings, towers, bridges, offshore oil rigs, water tanks, and marine applications. Marshall Space Flight Center, Alabama NASA Marshall Space Flight Center’s Fluid Structure Coupling (FSC) technology is a highly efficient and passive method to control the way fluids and structures communicate and dictate the behavior of a system. This technology has the demonstrated potential to mitigate a multitude of different types of vibration issues, and can be applied anywhere internal or external fluids interact with physical structures. For example, in a multistory building, water from a rooftop tank or swimming pool could be used to mitigate seismic or wind-induced vibration by simply adding an FSC device that controls the way the building engages the water.

Posted in: Briefs, Mechanical Components, Automation, Water, Vibration


The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.