Sensors/Data Acquisition

Load-Indicating Sensor for Lines and Cords

Tension-indicating device will indicate the peak load that the cord is subjected to. Lyndon B. Johnson Space Center, Houston, Texas During the development of parachute systems, it is desirable to size the lines correctly, and to pack and deploy the parachute in a manner that produces uniform loading among the lines. Analytical methods would greatly reduce the cost of development; however, test verification is essential. This is extremely difficult to do with small lines, as there may be hundreds of lines in a multi-parachute deployment. The load-indicating sensors developed at JSC are extremely small, do not interfere with packing, do not change the load capacity of the lines, and can be inserted into an existing, assembled parachute system.

Posted in: Briefs, TSP, Sensors

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Wide-Input-Range Signal-Conditioning Input Interface for Motor Position Sensing in Extreme Environments

NASA’s Jet Propulsion Laboratory, Pasadena, California Motor position sensing is a critical application in a number of systems. Galvanically isolated sensors for motor position sensing are strongly favored in both industrial and extreme-environment applications. Two examples of these sensors are resolvers and linear variable differential transformers (LVDTs). Both of these utilize a transformer with a primary and two secondary windings whose coupling constants are variable with either shaft angle (for the resolver) or position (for the LVDT). These sensors are utilized by driving the primary winding with a sinusoidal signal and measuring the relative amplitudes of the secondary winding outputs. The resulting output waveforms have wide range (up to ±20 V for some applications), and are usually ground-referenced. It is thus critical to have a signal-conditioning interface circuit that can sense voltages across wide ranges and convert them to voltages that a standard integrated circuit can process.

Posted in: Briefs, TSP, Sensors

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Advanced Methodology for Precisely Simulating RTD Sensor Types

This technology has applications in plant process simulation, hardware-in-the loop testing of electronic control units in automobiles and avionics, and spacecraft and satellite systems testing. VTI Instruments Corporation, Irvine, California Resistance thermometers, also called resistance temperature detectors (RTDs), are very common sensors used for temperature measurement. Their reliability, ruggedness, wide range, and value make them popular in the process industry and research laboratories alike. A wide range of instruments, PLC I/O systems, data acquisition, and control systems are designed to interface with these sensors and perform actions based on their measured value. Testing of such systems requires a sensor to be simulated, where hardware-in-the-loop testing is mandatory. Often the validation of such systems will end up being a complex issue if not properly planned.

Posted in: Briefs, Sensors

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Microwave Radar Sensor Module

Applications include detection of humans from a distance for search and rescue, and non-contact detection of a patient’s vital signs. NASA’s Jet Propulsion Laboratory, Pasadena, California Existing implementations of continuous wave (CW) radar are not packaged appropriately for use as part of a heartbeat detection system for disaster search and rescue. They use separately packaged microwave components and laboratory test equipment, and require substantial skill to operate properly, including setup, calibration, and interpretation of the data.

Posted in: Briefs, TSP, Sensors

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Microphones and Accelerometer Sensors Network for Acoustic Diagnostics (MASNAD)

This network of sensors can pinpoint sounds in any mobile platform. NASA’s Jet Propulsion Laboratory, Pasadena, California A system has been developed using sound to detect problems on rovers or other remote platforms autonomously. It consists of a sensor array of microphones and accelerometers that uses the differences in the sounds generated by the motors, gears, instruments, or other devices being monitored to determine abnormal operation conditions.

Posted in: Briefs, TSP, Detectors, Sensors

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MEMS Gyroscope with Dual Interferometric Sense Elements

This sensing technique enables the use of a large proof mass with very low thermomechanical noise. John F. Kennedy Space Center, Florida High-performance inertial sensors, such as ring laser gyroscopes or fiber optic gyroscopes, have sufficient performance to enable “dead reckoning” navigation for adequate periods of time. Smaller microelectromechanical system (MEMS) inertial sensors, such as MEMS gyroscopes and MEMS accelerometers, typically have relevant performance characteristics that are 10 or 100 times worse than high-performance inertial sensors. As a result, these small MEMS inertial sensors must be aided by a global positioning system (GPS) if they are to be used for navigation.

Posted in: Briefs, TSP, Sensors

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MMOD Risk Mitigation Technology for Spacecraft Thermal Protection Systems

The ingestion of high-temperature plasma through a small breach could be prevented by providing adequate counter pressure. Lyndon B. Johnson Space Center, Houston, Texas The proposed concept uses sensors to detect high-temperature plasma ingestion during entry through a breach in the thermal protection system (TPS) caused by a micrometeoroid orbital debris (MMOD) impact. It uses consumables usually available on human-rated spacecraft such as gaseous nitrogen (or helium) and water to maintain spacecraft structural integrity by keeping it within the temperature limits via an evaporative cooling effect and to equalize the internal and external pressures to prevent high-temperature plasma from flowing further into unintended areas. Once a breach was detected, the system could be activated autonomously or manually by the flight crew, or by telemetry from the ground crew.

Posted in: Briefs, TSP, Detectors, Sensors

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