Motion Control

Actuators

Nook Industries (Cleveland, OH) offers Series 500™ programmable actuators designed for continuous duty and long service life. They incorporate a direct or toothed-belt drive for high mechanical efficiency. Ball screw-driven programmable actuators are made with high-strength materials, and are available in parallel and in-line models with either a servomotor or stepper motor. The screw shaft is constructed with medium-carbon, induction-hardened alloy steel, and the ball nuts are manufactured from high-grade bearing steel. Both ball screw and nut are heat-treated to a surface hardness of 56 HRC.

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Machine Control

Unitronics (Quincy, MA) has introduced Samba, a palm-sized PLC with HMI and onboard I/Os for machine control that features a color 7" HMI panel. The 16-bit touchscreen enables data entry and display of variable data, including color trend graphs and alarm screens. Samba supports 24 userdesigned screens and 5-MB images per application. The integrated PLC offers features including two auto-tuned PID loops, time-based RTC control, data logging, and recipes. The internal memory holds 112 KB of application logic, plus 512K for fonts and 5 MB for images. Onboard I/Os offer digital, analog, and high-speed functionality.

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Accelerometer Chips

Silicon Designs (Kirkland, WA) offers industrial-grade MEMS variable capacitive accelerometer chips and modules for zero- to medium-frequency instrumentation applications. Onboard voltage regulation and an internal reference minimize temperature and voltage changes while eliminating additional external power regulation requirements. Each sensor is made to be virtually identical, allowing users to swap out parts in the same g range with few to no testing modifications. This also provides a plug-and-play solution for almost any application.

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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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Magnetic Encoders

POSITAL (Hamilton, NJ) introduced new models of IXARC magnetic encoders that combine incremental and absolute rotation measurement capabilities in a single, compact package. Absolute encoders provide a control system with a report of the rotational angle and rotation count at a specific point in time; incremental encoders provide a signal pulse each time the encoder shaft rotates by a specified angle. The hybrid encoders are based on the company’s magnetic measurement technology, and offer shock, dust, and moisture resistance. The hybrid incremental and absolute rotary encoders have communications interfaces that support both measurement modes: RS-422, HTL, or TTL for incremental readings; and SSI for absolute measurements. Available multi-turn versions can count up to 64,000 revolutions, while incremental measurements have resolutions as high as 16,384 pulses per revolution. For Free Info Visit http://info.hotims.com/55588-300

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