Innovative Motion Control Devices

DN Staff

June 17, 2002

5 Min Read
Innovative Motion Control Devices

All-in-one distributed drives

In theory, a distributed architecture simplifies equipment design by putting right-sized automation as close as possible to the driven machine elements. The SIMODRIVE POSMO series of distributed drives takes that notion to its logical end by packaging a motor, motor drive, position controller, and feedback devices in a single, easily installed unit. Power and a PROFIBUS-DP connection are all that's needed to make the units operable on a distributed machine-control network. POSMO A series drives include 75W, 24V dc and 300W, 48V dc models. The POSMO SI series comprises 600V dc units from 1.9 kW to 5.7 kW output. For applications where space constraints won't permit the fully integrated design, separate series POSMO CD and POSMO CA drives combine the drive, controller, and feedback in a package for mounting near a separate motor. The CD and CA drives accommodate 600V dc (9A and 18A options) and 3-phase, 9A, 400 to 480V ac power respectively. Siemens Energy & Automation, Inc.: Enter 576

New-look motor boasts high efficiency

A slotless, brushless, permanent-magnet servomotor of unusual design promises energy efficiency over a wide speed range. The ThinGap TG 1500S uses NdFeB magnets, an iron outer frame, and a miniature air gap between rotor and stator to eliminate electrical hysteresis and the resulting low-speed cogging. It also greatly reduces armature inductance and line-to-line resistance. "The result is a very high efficiency, high power-density motor," says Jerry Yankie, spokesperson for the motor's developer and manufacturer, G&G Technology. While he cautions that overall system efficiency is a function of the motor and the motor controller necessary with a brushless design, the company's published performance curves show near 90% efficiency at 4,500 rpm while delivering 30 oz-inch of torque. Maximum continuous torque for the 2.375-inch OD, 2.180-inch long motor is 115 oz-inch at 2,400 rpm on 24V dc, 15.6A power. G&G Technology, Inc.: Enter 577

Small step with a big twist

Rare-earth magnets and optimized design let the latest additions to the PK series of miniature stepping motors lay claim to the prize for the highest torque-per-unit-volume specification available. The new two-phase hybrid steppers in 28- x 28-mm frame size deliver up to 16.6 oz-in of holding torque (for the 51.5-mm length model, shorter models also available) in bi-polar excitation mode. The 52 mm long version of the 35- x 35-mm frame-size model puts out 54 oz-in maximum in the same mode. Shaft speeds under lighter loading exceed 4,000 and 3,000 rpm for the motors, respectively. The use of rare-earth neodymium magnets, pioneered on larger PK motors, partly explains the performance boost in these smaller motors. "When you go down in size there are issues, whether it's back-emf or the strength of the shaft, that have to be taken into consideration too," says John Wong, senior engineer at Oriental Motor. The reliable, robust final design was an optimization of magnetic and mechanical engineering. "I think the newest innovation is being able to do it, that's all." Applications for the new motors include medical and scientific instruments, pointable security cameras, and robotics. Oriental Motor U.S.A. Corp.: Enter 578

Actuators like it hot

HSI high-temperature, size 17 hybrid linear actuators incorporate Class F insulation, enabling them to operate safely at temperatures up to 155C. Who needs that level of thermal protection? Maybe you. Most motors come with Class B insulation, which lets them operate to 130C. That seems pretty high until you consider the environments in which some motors and actuators are asked to perform in. The ambient temperature combined with motor waste heat can easily exceed a motor's rated thermal allowance, says Joe Rossi, applications manager at Haydon Switch & Instrument. "If the ambient temperature is routinely above 55C, and they need to run the motor continuously, then we recommend that they go to a high-temperature motor." The new insulation, coupled with a proprietary rotor whose molded threads have a lower coefficient of friction than a typical tapped-nut and leadscrew design, give the actuator its higher temperature rating and improve its durability at the same time, he says. The high-temperature actuators are available in resolutions from 0.002 inch to 0.00006 inch per step and nominal thrust forces to 50 lbs. Haydon Switch & Instrument, Inc.: Enter 579

Momentous motor

The Model 000-0182 brushless dc motor demonstrates that although electronic controllers make brushless motors possible, it's the mechanical engineering that makes them work in a given application. Initially designed to keep the reflective polygons in laser bar-code scanners spinning with great precision, the 1.52-inch diameter, 3 oz-inch torque (typical) device shows great attention to detail. Its outer-rotor design is crucial to the application. "If somebody's trying to keep the speed stable in their system, then the rotor's higher inertia stores energy and allows [the motor] to get by any perturbations it might see by using that stored energy," explains Keith Bosecker, executive vice president at Servo Magnetics, Inc. The relatively large rotor face simplifies connection to driven elements. It's supported by precision bearings and is balanced in two planes to provide low acoustical noise. All together, the design delivers mean time between failure of better than 25,000 hours. Capable of speeds in excess of 20,000 rpm, custom windings are available to tailor the design to other applications. Servo Magnetics Inc.: Enter 580

Motion programming made simple

To create the code for industry-standard programmable motion control, get familiar with the specialized application program interfaces for the most commonly used software-Visual Basic, C++, LabVIEW, etc. Or use the new Motion Assistant application-development tool from National Instruments. Motion Assistant is an easy-to-use, highly graphical interface that operates one level above the traditional programming environments. "With Motion Assistant, you can configure various move types and when you're done, create LabVIEW or other code directly," says Jayson Wilkinson, product manager, motion control at National Instruments. "You don't have to be familiar with how to program the motion controller, you just have to know what you want to do, then Motion Assistant figures out all the code to do that for you." The tool simplifies motion planning and coding, but it also allows users full access to high-level programming capabilities, such as data acquisition from vision or other sensor systems. So, while it was designed to make motion programming easier for neophytes, experienced motion engineers will find that it accelerates their program development as well. National Instruments: Enter 581

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