Motion Control

Advantages of Servo Motor and Direct Drive Technology

For many years, stepper motors have been the most popular type of electric motor designed into instrumentation for a wide variety of reasons. Stepper motors have become increasingly commoditized, and can be sourced easily. In addition, the growing “maker movement” has simultaneously made them more popular and reduced their cost. Unlike servo motors, stepper motors don’t require tuning to optimize their performance. What’s more, scaling and motion commands are typically quick and simple to execute using stepper motors. Servo motors often require a bit more expertise in executing complicated (torque, velocity, or position) loop closures. Finally, micro-stepping allows most modern drive electronics to step or increment a stepper motor to a resolution of 50,800 steps per revolution or higher.

Posted in: Articles, Motion Control, Motors & Drives

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An Inside Look at Electromechanical Power-Off Braking Options

Making the right choice between spring set and permanent magnet brakes can impact safety, durability, maintenance, and performance. Power-off brakes are designed to hold or stop motion in the absence of power. Adding an electrical current releases the brake, freeing the load for motion. Given the safety ramifications of keeping a system locked in place until it is powered up, motion control system designers tend to specify power-off brakes more often than power-on brakes. There are, however, two different failsafe brake technologies: one uses compression springs to hold its load in place, and the other uses permanent magnets. Each has specific strengths and weaknesses, and knowing the difference can impact safety, durability, cost, and performance.

Posted in: Articles, Motion Control

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Dust Tolerant Connectors

The ruggedized housing for electrical or fluid connectors is designed to withstand harsh environments and rough handling. John F. Kennedy Space Center, Florida NASA’s Kennedy Space Center has developed a novel ruggedized housing for an electrical or fluid umbilical connector that prevents intrusion of dust, sand, dirt, mud, and moisture during field use under harsh conditions. The technology consists of a pair of hand-sized protective umbilical interface housings, each containing a connector with an integrated end cap. When the end cap covers the connector, the connector is protected. Each housing has a unique lever assembly connected to the end cap that, when squeezed, flips the end cap up to expose the connector. When in the up position, the two end caps face each other. To mate the connectors, the levers on both housings are squeezed, raising the end caps, and the two umbilicals are joined and twisted to couple them. Once the connectors are mated, the levers on both housings are released. This simultaneously seals both the umbilicals and the end caps. When dealing with cryogenic connectors, a purge can be applied to the housings to prevent icing when the connectors are demated.

Posted in: Briefs, Mechanical Components, Fluid Handling, Machinery & Automation

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Motor Drive

The RoadRunner SoftStep R213S microstepping motor drive from Testra Corp. (Tempe, AZ) features an onboard processor that treats the input steps as small vector moves, and chains them together with 250 or 256 microsteps per regular motor step with controlled accelerations. Dual chopper stabilized current comparators and auto-calibration eliminate communication discontinuities and maintain sine wave drive, reducing motor noise. The drives are equipped with jumpers installed with a divisor setting of 10 to make them Geckodrive compatible; jumpers can be reconfigured by the user. The drive microsteps in either 250 or 256 increments per step for DS (double-step) settings, 1 (full-step), 2 (half-step), 4, 8, 16, 32, 64, 128, and 256. The drive measures 2.5 × 2.5 × 0.825", input power is 20VDC – 80VDC, and current drive is 1 to 7 amps. Other features include resistor programmable current, opto-isolated inputs, and step frequency to 5 Mhz. Available options include custom waveforms to match individual motor characteristics, and user-programmable waveform. For Free Info Visit http://info.hotims.com/61062-301

Posted in: Products, Manufacturing & Prototyping, Motion Control

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Positioners

ALM Positioners (Rock Island, IL) released the Model MHL1P 10,000-pound-capacity single-column positioner that features 68.5" vertical travel in 35 seconds; a pendant-controlled, 4-HP, column-mounted hydraulic unit for lifting and lowering; solenoid- controlled safety pawls; 360-degree CW or CCW rotation; a rotator with 267,200 inch-pounds of torque; and a 48" base. It is offered as a dual-motor rotator and variable frequency drive (variable speed rotation of .75 to 2.3 RPM), as well as a single rotator.

Posted in: Products, Manufacturing & Prototyping, Motion Control

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Linear Slide

Haydon Kerk Motion Solutions (Waterbury, CT) introduced the WGS Wide Guide Screw linear slide that utilizes a screw-driven carriage. Length and speed are not limited by critical screw speed, allowing high RPM, linear speed, and long stroke lengths. The slide offers stroke options of 6, 12, and 18" in three leads (0.1, 0.5, and 1.0"). Each slide comes with a size 17 and a size 23 motor mount. The slide utilizes sliding plane bearings on a low-profile aluminum guide rail. The lead-screw is made of stainless steel, and all moving surfaces include Kerkite® polymers running on a Kerkote® TFE coating. The slides come with wear-compensating, anti-backlash-driven carriages. Additional driven or passive carriages can be added, along with application-specific customization. Linear guides without the drive screw also are available. For Free Info Visit http://info.hotims.com/61062-302

Posted in: Products, Manufacturing & Prototyping, Motion Control

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Angle Sensors

Novotechnik U.S. (Southborough, MA) introduced the RSX-7900 Series angle sensors that provide up to IP69K ingress protection and ISO13849 PL-d safety compliance in a non-contacting design. The sensors are available in six standard measuring ranges with angles from 0 to 60, to 0 to 360 degrees with unrestricted rotation. Resolution is 12-bits across a 4 to 20 mA output, with linearity to ±1% at ≥ 90 degrees. Repeatability is 0.2°, and update rate is 5 kHz. Single and dual redundant versions are available. The sensors offer anodized aluminum housing with a stainless steel shaft for corrosion protection with salt and spray resistance. Axial and radial shaft loading is up to 300 N via a double-row angular ball bearing design. The 70-mm-diameter sensor has a nominal length of 35 mm, and is available with a choice of shaft styles. For Free Info Visit http://info.hotims.com/61062-304

Posted in: Products, Manufacturing & Prototyping, Motion Control

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