Motion Control

Analyzing Rollover Stability of Capsules With Airbags Using LS-Dyna

This method interpolates data to predict the stability boundaries for a capsule on airbags.

As NASA moves towards developing technologies needed to implement its new Exploration program, studies conducted for Apollo in the 1960s to understand the rollover stability of capsules landing are being revisited. Although rigid body kinematics analyses of the rollover behavior of capsules on impact provided critical insight to the Apollo problem, extensive ground test programs were also used. For the new Orion spacecraft, airbag designs have improved sufficiently for NASA to consider their use to mitigate landing loads to ensure crew safety and to enable reusability of the capsule.

Posted in: Briefs, TSP, Motion Control, Stability control, Airbag systems, Spacecraft
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Test Fixture for Isolation of Vibration Shaker from G-Loading

Combined testing is possible in a controlled, calibrated, and repetitive manner.

The first step in implementing the capability to test sensitive launch vehicle instruments in a combined environment has been completed. The test environment consists of specific vibration spectra induced under sustained Gs, using NASTAR’s ATFS-400 centrifuge. Fixtures allow mounting of the device under test (DUT) to a vibrational shaker in a centrifuge for generating moderate G-loading (1.4 to 9G) such that the vibrational shaker’s capabilities are only slightly affected by the G-loads applied during testing. Two configurations were designed, with the vibrational load parallel to the G-loads, and with the vibration loads transverse (at right angles) to the G-loads. The results are extremely encouraging, and demonstrate the potential of the NASTAR centrifuge to perform this kind of combined testing in a controlled, calibrated, and repetitive manner.

Posted in: Briefs, TSP, Motion Control, Aircraft instruments, Aircraft instruments, Vibration, Vibration, Launch vehicles
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Rotary Series Elastic Actuator

The actuator provides motion and sensing for the degrees of freedom in the upper arm of a dexterous humanoid robot.

In order to perform human-like movement, an actuator is placed at each degree of freedom (DOF) in a humanoid robot. Additionally, these actuators must be packaged in an arrangement that approximates human structure and appearance. In this innovation, a rotary actuator assembly incorporates a brushless DC motor, a gear reduction, a variety of sensors, and a custom planar torsion spring to provide motive force, passive compliance, and torque sensing within an anthropomorphic package. The actuator, in various size scales, was designed for the humanoid robot described in “Dexterous Humanoid Robot,” (MSC-24739), NASA Tech Briefs, Vol. 38, No. 6 (June 2014), p. 52.

Posted in: Briefs, Motion Control, Sensors and actuators, Sensors and actuators, Robotics
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Linear Motor Stages

Prior Scientific (Rockland, MA) offers HLD117 linear motor stages for microscope automation. They feature repeatability of 0.15 μm, scanning speeds of up to 300 mm per second, and low-velocity ripple even at speeds down to one micron per second. A low-profile, flat-top design and ultra-quiet operation make the stage suited for OEM and end user applications. The stages are compatible with the company’s NanoScan Piezo Z stages, PLW20 Well Plate Loaders, and a range of sample holders.

Posted in: Products, Motion Control
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Optical Encoders

POSITAL-FRABA America (Hamilton, NJ) has introduced optical encoders with EtherCAT that provide high-speed data for positioning and speed control with cycle times of up to 62 μs. Using a distributed clock function, they allow users to synchronize axes with a deviation of <1 μs. The EtherCAT encoders support cable redundancy, so if special PLCs with two network cards are used, a maximum of one cycle is lost. A round axis functionality enables users to implement applications with non-binary gearing factors. The firmware can be updated through standard configuration tools such as TwinCAT. Other features include up to 16-bit resolution and 14-bit revolution, up to IP67 environmental protection, and optional stainless steel and explosion-proof housings.

Posted in: Products, Motion Control
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Pumping Efficiency Into Electric Motors

University of Adelaide (Australia) researchers are using new magnetic materials to develop revolutionary electrical motors and generators that promise significant energy savings. They have used the new motors to develop patented highly efficient water pump systems with potential widespread application.

Posted in: News, Motors & Drives
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NASA Decelerators Slow Payloads Traveling at Supersonic Speed

What will it take to land heavier spacecraft on Mars? How will engineers slow large payloads traveling at supersonic speeds in a thin Martian atmosphere? The Low Density Supersonic Decelerator (LDSD) mission will seek to answer these questions.

Posted in: News, Aerospace, Motion Control, Motors & Drives, Power Transmission, Automation, Test & Measurement
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New Strain Gauge Enables 'Soft Machines'

Purdue University researchers have developed a technique to embed a liquid-alloy pattern inside a rubber-like polymer to form a network of sensors. The approach may be used to produce "soft machines" made of elastic materials and liquid metals.

Such an elastic technology could be used to create robots with sensory skin, as well as develop stretchable garments that interact with computers.

"What's exciting about the soft strain gauge is that it can detect very high strains and can deform with almost any material," said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University. "The skin around your joints undergoes about 50 percent strain when you bend a limb, so if you wanted to have sensory skin and wearable technology that tracks your movement you need to employ soft, stretchable materials that won't restrict your natural range of motion."

Source

Also: Learn about Thermal Properties of Microstrain Gauges.

Posted in: News, Materials, Metals, Plastics, Motion Control, Automation, Robotics, Sensors
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High-Temperature Actuators for Aircraft Propulsion Systems

Future “more electric aircraft” (MEA) will require electric actuation systems for control surfaces and engine controls. Electric motors, drive electronics, and mechanisms are essential elements of aircraft actuation in MEAs that incorporate Electro-Magnetic Actuators (EMAs). High-temperature environments experienced in aircraft applications place demands on actuator components, materials, and insulation systems that dictate the use of new technologies and materials.

Posted in: Articles, Motion Control, Flight control actuators, Flight control actuators, Thermal management, Thermal management, Heat resistant materials, Electric motors
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Probe Positioning System for Antenna Range

Three or more cables provide the desired positioning.

In situ measurements of antenna patterns on rovers in a simulated terrain are difficult to make with conventional antenna range techniques. The desired pattern data covers a hemisphere above the antenna of interest, which is close to the ground. This is incompatible with traditional measurements that place the antenna under test on a movable support that tilts and rotates.

Posted in: Briefs, TSP, Motion Control, Antennas, Sensors and actuators, Antennas, Sensors and actuators, Spacecraft
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