Motion Control

Cooling Solution Helps NASA Get Closer to Mars

Cold conditioning systemAggrekoHouston, TX281-985-8200www.aggreko.com

Posted in: Application Briefs, Motion Control, Research and development, Cooling, Spacecraft

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Custom Brakes Meet the Challenges of Gearless Motor Elevators

Standard braking systems could not meet the difficult speed, energy, and dynamic torque constraints.A manufacturer of low and high-rise elevators faced a challenge when customers began calling for a flexible elevator to meet the needs of the growing mid-rise, mixed-use building market. The global construction boom of mid-rise buildings can be attributed to several factors. Developers are more apt to build “short” because it requires less capital and the time to get permits approved is reduced considerably, especially in developing countries.

Posted in: Application Briefs, Motion Control

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New Products: April 2017 Motion Design

Variable Frequency DrivesThrough a new partnership, variable frequency drives (VFDs) from American Control Electronics (South Beloit, IL) will now be offered as a product add-on to Brother Gearmotors’ portfolio of sub-fractional AC gearmotors and reducers. OEMs have access to an optimized VFD for the Brother sub-fractional power range instead of purchasing an offthe- shelf VFD that may not be the best fit for the application. For example, a user buying a sub-fractional HP (1/100th to 1/6th HP) gear motor will not have to choose an off-the-shelf VFD rated for 1/4 HP. ACE’s microprocessor-based VFDs control AC motor speed and torque by varying input frequency and voltage.

Posted in: Products, Motion Control

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Differential Measurement System

The Measuring Division of Kaman Precision Products, Inc. (Middletown, CT) has released the KD-5100 differential measurement system, which provides resolution to a nanometer of positional change. Featuring a small package size – only 2 x 2.12 x 0.75 inches thick – the KD-5100 is a good choice for applications where space is a limiting factor. It is manufactured to MIL-H-38534, with MIL-SPEC components used throughout the electronics module wherever possible. The KD-5100 features rugged construction, with a mean time between failures of better than 238,000 hours in a space flight environment and 55,000 hours in a tactical environment.Click here to learn more

Posted in: Products, Products, Data Acquisition, Motion Control, Positioning Equipment

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Evaluation Standard for Robotic Research

Universal benchmarks can standardize the measurement of robotic manipulation tasks.The Yale-CMU-Berkeley (YCB) Object and Model Set provides universal benchmarks for labs specializing in robotic manipulation and prosthetics. About two years ago, Aaron Dollar, an associate professor of mechanical engineering and materials science at Yale University, came up with the benchmark idea to bring a level of specificity and universality to manipulation tasks in robotics research. He enlisted the help of two former colleagues in the robotics community, Dr. Siddhartha Srinivasa from Carnegie-Mellon University and Dr. Pieter Abbeel of the University of California, Berkeley.

Posted in: Briefs, Motion Control, Automation, Kinematics, Research and development, Robotics, Quality standards, Biomechanics

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Mechanisms for Achieving Non-Sinusoidal Waveforms on Stirling Engines

The current state-of-the-art Stirling engines use sinusoidal piston and displacer motion to drive the thermodynamic cycle and produce power. Research performed at NASA Glenn has shown that non-sinusoidal waveforms have the potential to increase Stirling engine power density, and could possibly be used to tailor engine performance to the needs of a specific application. However, the state-of-the-art Stirling engine design uses gas springs or planar springs that are very nearly linear, resulting in a system that resonates at a single frequency. This means that imposing non-sinusoidal waveforms, consisting of multiple frequencies, requires large forces from the drive mechanism (either the alternator or the crank shaft). These large forces increase losses, and increase the size and requirements of the control system. This innovation aims to reduce the external forcing requirements by introducing internal mechanical components that provide the forces necessary to achieve the desired waveforms.

Posted in: Briefs, Mechanical Components, Mechanics, Motion Control, Alternators, Crankshafts, Engine efficiency, Stirling engines

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Improving Stirling Engine Performance Through Optimized Piston and Displacer Motion

Stirling engines typically achieve high efficiency, but lack power density. Low power density prevents them from being used in many applications where internal combustion engines are viable competitors, and increases system costs in applications that require Stirling engines. This limits their operating envelope in both terrestrial and space applications. Sinusoidal piston and displacer motion is one of the causes of low power density. Previous work proposed solving this problem by replacing sinusoidal waveforms with waveforms that more closely approximate those of the ideal Stirling cycle. However, when working with real engines, imposing ideal waveforms has been shown to reduce power density and efficiency due to increased pressure drop through the regenerator and heat exchangers.

Posted in: Briefs, Fluid Handling, Mechanical Components, Mechanics, Motors & Drives, Engine efficiency, Pistons, Stirling engines

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