Motion Control

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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The Less is More Approach to Robotic Cable Management

In recent years, cable management has come into the limelight because machine reliability has increased dramatically, even though robots have grown more complex. Unfortunately, the methods used to attach and guide cables have not quite followed suit. While managing cables and hoses is often an afterthought in most designs, it is truly a vital part of any well-functioning robot.

Posted in: White Papers

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Energy Chain® Cable Carriers: The Right Material for Any Application

Cable carriers are often an afterthought for many design engineers, but many times, they are the key to protecting vital cables and hoses on automated machinery. Cable carriers can be considered the lifeline that keeps a machine running. They not only guide the cables and hoses, but protect against harsh external elements, including dirt and dust, flying debris, chemicals and excessive heat.

Posted in: White Papers

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TechTalk Design Advice Series: The Cable Distribution Rules You Need To Obey

The key advantage of a cable carrier is that bus and motor cables, pneumatics, electrics and hydraulics can all be guided safely in one system. However, correctly arranging each cable and hose within your chosen cable carrier according to the recommended spacing requirements is vital if you want to prolong the service life of your system.

Posted in: White Papers

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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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