Motion Control

Thermoplastic Racks Open Up New Motion Control Applications

Rack and pinions are linear actuators that play a critical role in a wide range of linear motion control applications. While rack and pinions are commonly thought of as a timeless technology, several new developments have helped provide significant performance improvements in specific applications. One new approach, the Roller Pinion System, replaces the traditional rack and pinion with bearing-supported rollers, increasing positional accuracy, speed and durability.

Posted in: Application Briefs

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Autonomous Robots Keep Warehouse Running Green

YLOG, a startup company in Austria, uses an intelligent and very environmentally friendly logistics system that is winning an increasing number of customers. The technology makes use of individual, freely moving Autonomous Intelligent Vehicles (AiVs) that detect each other, observe right-of-way rules, recognize one-way routes, and complete their tasks fully autonomously without intervention from or coordination by a central computer.

Posted in: Application Briefs, Articles, Motors & Drives, Machinery & Automation, Robotics

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Reducing Power-On/Off Glitches in Precision DACs

Voltage glitches are common in a signal chain path, especially when the system is being powered up or down. Depending on the peak amplitude and glitch duration, the end result in the system output can be catastrophic. One example is an industrial motor control system where a digital-to-analog converter (DAC) drives the motor drivers to control motor spin. If the glitch amplitude is higher than the motor driver’s sensitivity threshold, the motor could be spinning without control in any direction when the system is powered up/down.

Posted in: Briefs, Power Management, Motors & Drives

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Piezoelectric Actuated Inchworm Motor (PAIM)

This linear piezoelectric actuator can operate at temperatures of 77 K or below. NASA’s Jet Propulsion Laboratory, Pasadena, California Conventional piezoelectric materials, such as PZTs, have reasonably high electromechanical coupling over 70%, and excellent performance at room temperature. However, their coupling factor (converting electrical to mechanical energy and vice versa) drops substantially at cryogenic temperatures, as the extrinsic contributions (domain wall motions) are almost frozen out below 130 K.

Posted in: Briefs, TSP, Fluid Handling, Motors & Drives

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Advanced Rolling Mechanics Analysis (AROMA) 1.0

Lyndon B. Johnson Space Center, Houston, Texas AROMA uses a boundary-element formulation to calculate normal and shear pressure distributions and sub-surface stresses for elastic bodies in contact. In addition to handling static normal and sheer loading, it also solves the contact problem for rolling elements such as bearings, traction drives, and wheel-to-rail interfaces. AROMA is a powerful and flexible tool for studying the tractive forces that arise during rolling in combination with kinematic effects, such as creepage and spin that are related to rolling element alignment. This GUI-based tool was developed in MATLAB, and can run within the MATLAB environment or as a standalone application.

Posted in: Briefs, Measuring Instruments

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Reactionless Drive Tube Sampling Device and Deployment Method

Springs and a counter-mass create a powerful and stable sampling device. NASA’s Jet Propulsion Laboratory, Pasadena, California A sampling device and a deployment method were developed that allow collection of a predefined sample volume from up to a predefined depth, precise sampling site selection, and low impact on the deploying spacecraft. This device is accelerated toward the sampled body, penetrates the surface, closes a door mechanism to retain the sample, and ejects a sampling tube with the sample inside. At the same time the drive tube is accelerated, a sacrificial reaction mass can be accelerated in the opposite direction and released in space to minimize the momentum impact on the spacecraft. The energy required to accelerate both objects is sourced locally, and can be a spring, cold gas, electric, or pyrotechnic. After the sample tube is ejected or extracted from the drive tube, it can be presented for analysis or placed in a sample return capsule.

Posted in: Briefs, TSP, Motors & Drives

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Developing Ceramic-Like Bulk Metallic Glass Gears

This technology has applications in gears, bearings, and gearboxes for automotive, spacecraft, and robotics. NASA’s Jet Propulsion Laboratory, Pasadena, California This invention describes systems and methods for implementing bulk metallic glass-based (BMG) macroscale gears with high wear resistance. This invention creates bulk metallic glasses (BMGs) with selected mechanical properties that are very similar to ceramics, such as high strength and resistance to wear, but without high melting temperatures. Ceramics are high-strength, hard materials that are typically used for their extremely high melting temperatures. Because of their extreme hardness, ceramics are optimal materials for making gears, due to their low wear loss. Unfortunately, ceramics suffer from low fracture toughness (typically <1 MPa·m1/2), and their high melting temperatures prevent them from being cast into net-shaped parts. Ceramic gears, for example, must be ground to a final shape at great expense.

Posted in: Briefs, Ceramics, Metals

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