eNewsletter 08/08/07
| Introduction |
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Welcome to the first edition of the Mechatronic Design e-newsletter, brought to you by the editors of Electronic Design, Machine Design, and Motion System Design. You are receiving this because you've subscribed to some of our other on-line newsletters, and we thought you might be interested in sharpening your interdisciplinary design skills.
Over the next few months you will see three more samples of the Mechatronic Design newsletter. If you wish to continue receiving it, you must subscribe by clicking on one the signup links that follow the enclosed information. If you don't want it, do nothing, and the newsletter will automatically stop after the sample period. We hope you find the information contained in these monthly mailings useful, and that it helps you as push ever deeper into interdisciplinary design space.Thanks for your time and have a great day.
-- Larry Berardinis
lberardinis@penton.com
| Features |
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Close quarters can make the specification process tricky for magnetostrictive sensors that have no external housings. Magnetostriction as a positionsensing technique has long been used in industrial machines. But another variant of this technology has emerged to handle situationsthat need to embed smaller sensors within aproduct to cut size and cost. Called magnetostrictive-core sensors, these new devices are basically conventional magnetostrictive sensors without their housing. Getting rid of the housing lets designers embed them in applications such as sprayers, dispensing machines, fastener magazines, X-Y positioners, small presses, clamps, grippers, and many other assembly and dispensing tools.
The packaging industry's most successful rapid transfer robot -- the Delta robot -- was developed in Switzerland during the early 1980s by Reymond Clavel. Since then, this lightning-quick, spiderlike mechanism has spread to factories around the world, proliferating in packaging, medical, and pharmaceutical applications. Their forte is pick-and-place, where they are often deployed in pods of up to 20 synchronized systems that collectively handle 100 to 2,500 products per minute.
The need for productivity that spawned the development of Delta robots also drives the ongoing efforts to refine them. No matter how well they operate in terms of speed, accuracy, reliability, and uptime, it's never enough. As a result, robot builders are continually looking for ways to improve their designs and optimize components to meet tomorrow's ever more demanding needs. Not surprisingly, those who follow the interdisciplinary (mechatronic) upgrade path are finding success, especially when they focus on the torque-producing elements, servomotors and gears.
Motor Control Kits
Intelligent motor control can provide finer speed control and provide longer motor life -- making it one of the hottest areas in electronics. Ramping up the speed of a motor, instead of hitting it with a full power surge, not only reduces the wear and tear on the motor, but can also make the product it is used in operate more smoothly. Once some intelligence is provided for motor control support, it's possible to add more functions such as variable speed operation.
Motors come in a wide range of form factors and technologies. If you are looking for a good book on motors, check out "Electric Motors and Drives: Fundamentals, Types and Applications" by Austin Hughes (see ED# book review, ISBN: 0-7506-4718-3).
At the Robotics Institute on the campus of Carnegie Mellon, grad student Jonathan Hurst is following the age-old engineering principle, "Keep it simple," as he explores two-legged motion systems. His initial prototype, for example, is so simple it only has a single leg and is constrained to two dimensions: up and down, and forward and back. But he is confident his prototype will let him determine the role compliance or muscle and tendon springiness (the opposite of stiffness) play in establishing walking and running gaits. Eventually, he would like to see his work applied to two-legged walking robots. But that day may still be a long way off, he says.
His prototype, dubbed BiMasc (Biped with Mechanically Adjustable Series Compliance), consists of a hip, thigh, and shin segment, three motors that wind and unwind cables, five cable differentials made of pulleys, and a pair of springs. One motor controls leg length, one controls leg angle, and the third adjusts leg stiffness, which can take place on the fly. The robot is tethered, with power and control coming through an umbilical.
These days, everything from hand soap to candy bars comes in multiple versions. Behind all this variety are smart manufacturing plants that have the ability to collect, move, and package products into multiple formats.
Have it your way
Robots are at the forefront of this packaging trend. But reconfiguring robots to frequently changing requirements can be complex and time-consuming. For starters, line changes on non-homogeneous control systems can require several adjustments across multiple control systems, including machine control, process control, motion, and human-machine interfaces
Smart Motion Makes For A Smarter Design
If it moves, jumps, rotates, or vibrates, it usually contains a motor. Electric motors come in all types of devices, from tiny hard-disk drives to hybrid vehicles to locomotives. Intelligent motor control can be employed over this wide range of devices, delivering improved efficiency, longer life, and better fault control compared to simply applying power to a motor. Key to greater use of intelligent motor-control systems are low-cost microcontrollers and digital-signal-processing chips that target this market.
Unfortunately, simply throwing a basic microcontroller at the problem is rarely an option. Digital design is hard. Analog design is harder. Combine the two disciplines and you've got the doubly difficult design task of digital motor control. Intensifying the problem is the need for a microcontroller with analog peripherals. On top of that, motor-control-oriented microcontrollers typically include a significant timing component.
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© 2012 Penton Media Inc.
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