Motion Control

Evaluation of Rail Gun Technology for Launch Assist of Air-Breathing Rockets

John F. Kennedy Space Center, Florida

A prototype horizontal electromagnetic rail launcher has been demonstrated along with a corresponding theory. This system builds out of published work in augmented rail guns, but modifies this technology so that the motor can operate for seconds rather than milliseconds, and provide low acceleration (such as might be needed to launch an aircraft) rather than the extreme accelerations seen in the guns. The final system operates off of relatively low voltages (tens of volts), but with substantial currents. A lab bench prototype has been constructed and operated, demonstrating 13 Gs acceleration of a small 230-gram sled.

Posted in: Briefs, Aerospace, Motion Control, Motors & Drives, Propulsion, Aircraft, Launch vehicles

Using Harmonics to Control Flutter in Wings with Electrical Motors

This control system concept applies principles of forced aeroelasticity to distributed electric propulsion systems.

Armstrong Flight Research Center, Edwards, California

As aeronautics engineers develop innovative distributed electric propulsion systems, they face new challenges in ensuring that these innovative aircraft are safe as well as fuel efficient. In particular, these systems involve a large number of electrically driven fan motors mounted across a wing that induce vibrations that negatively affect the aircraft’s stability. These vibrations cause problems regardless of whether the motors are bottom-mounted, top-mounted, or wing-embedded.

Posted in: Briefs, Aeronautics, Motion Control, Motors & Drives, Propulsion, Vibration, Electric motors, Fans

Micropulse Detonation Rocket Engine for Nano-Satellite Propulsion

Goddard Space Flight Center, Greenbelt, Maryland

An efficient propulsion system would use a micropulse detonation rocket engine (–PDRE) for nano-satellite maneuverability in space. Technical objectives are to design, build, and conduct a small detonation tube experiment in order to explore the feasibility of using –PDRE for propelling a nano-satellite. The plan is to study the requirement and predict the performance of –PDRE using various candidate propellants, as well as to conduct ground experiments, demonstrate useful thrust, and measure the specific impulse in a two-year time frame, so that a follow-on project can be proposed in a future NRI Center Innovation Fund.

Posted in: Briefs, TSP, Aeronautics, Motion Control, Propulsion, Automation, Propellants, Rocket engines, Satellites

Experimental Testbed for 1-MW Turboelectric Distributed Propulsion Aircraft

A low-cost glider design mitigates risk in conducting experiments for cutting-edge “green” aircraft concepts.

Armstrong Flight Research Center, Edwards, California

Researchers at NASA’s Armstrong Flight Research Center are developing a concept aircraft for testing turbo-electric distributed propulsion (TeDP) experiments. TeDP generally involves providing thrust to an aircraft via wing-mounted ducted electric fans, which consist of an electric motor, a fan, stators, and other components surrounded by cylindrical ducting within a fan case. The fan motors are powered by a combined battery and turboelectric generator system. To sufficiently power an aircraft approximately 50 ft (≈15 m) in length and with a gross weight of 25,000 lb (≈11,340 kg), this system must be capable of generating 1 MW of power.

Posted in: Briefs, Aviation, Motion Control, Motors & Drives, Propulsion, Wings, Electric motors, Fans

Propellant Loading Visualization Software

Monitoring of complex propulsion pressure systems has been simplified with colors.

Goddard Space Flight Center, Greenbelt, Maryland

Complex pressure systems are utilized during testing in the propulsion branch as well as during the propellant loading stage of a mission. Keeping track of the state of such a system becomes more difficult as the complexity of such a system increases, and when extensive procedures are being followed. A book-keeping system is needed for visualizing these complex systems.

Posted in: Briefs, TSP, Motion Control, Propulsion, Software, Computer software and hardware, Imaging and visualization, Propellants

Computation of Wing Deflection and Slope from Measured Strain

Patent-pending methodology computes detailed wing loads during actual flight.

Armstrong Flight Research Center, Edwards, California

A lightweight, robust fiber-optic system is the technology behind a new method to compute wing deflection and slope from measured strain of an aircraft. This state-of-the-art sensor system is small, easy to install, and fast, and offers the first-ever means of obtaining real-time strain measurements that can accurately determine wing deflection and slope during flight. Such measurements are particularly useful for real-time virtual displays of wing motion, aircraft structural integrity monitoring, active drag reduction, active flexible motion control, and active loads alleviation.

Posted in: Articles, Briefs, Aeronautics, Aerospace, Aviation, Motion Control, Measuring Instruments, Wings

Specifying Actuators for Cleanroom Environments

Selecting the right actuator for use in any manufacturing operation involves a host of application-specific variables, including aspects such as the required stroke length, load capacity, acceleration, maximum speed, and positioning repeatability. Add a cleanroom specification to the list and the choice of available options becomes significantly smaller. Consider these questions to help make the best choice for your cleanroom application, whether it’s for the medical device, pharmaceutical, biotechnology, or semiconductor manufacturing industry.

Posted in: Articles, Motion Control, Sensors and actuators, Manufacturing processes, Test facilities

NASA's Hot 100 Technologies: Mechanical & Fluid Systems

Spring Joint Package with Overstrain Sensor

This flexible joint provides two degrees of freedom and a tremendous amount of compliance. The overstrain sensor joint has a passive and restoring force that allows the joint to return to a default position, and is also proportional to the amount of lateral deflection the spring has undergone; this allows the OS sensor joint to be used in many of the under-constrained situations that cause universal joints to lock up.

Posted in: Articles, Techs for License, Fluid Handling, Motors & Drives

Analyzing 6-Pulse Drive Harmonic Mitigation Techniques for Industrial Automation

Contemporary industrial automation control systems are employing variable frequency drives (VFDs) in ever-increasing numbers. VFDs give control engineers flexibility to precisely regulate the speed and torque of motors in a wide array of applications. The proliferation of these VFDs has brought increased attention to harmonic distortion created by these drives and their effects on the power system. A standard-pulse drive with no built-in harmonic mitigation controls may interfere with neighboring equipment, reduce equipment life, and create a serious negative impact on the quality of utility power. Looking at the theory of operation for the following harmonic mitigation techniques and their typical performance levels may help take the guesswork out of harmonic reduction for these power systems.

Posted in: Articles, Motion Control, Automation

Reliable Locking in High-Vibration Environments

Today’s PCB plug-in connectors must accommodate many trends, including increasing miniaturization, rising levels of performance of electronic components, and growing complexity in machine and system engineering.

Posted in: Articles, Motion Control, Connectors and terminals, Electronic equipment, Vibration

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