Integrated, Intelligent Motors & Controls Will Be in Your Future

An emerging class of motion control products—that combines motor, drive, controller, processing intelligence, feedback device, I/O points, communication, and more in one package—defies simple naming. Some systems add all the elements to the motor, others only a few. Integrated, intelligent motor and control (I2MC) unit is the tag name used here, although some of the systems co...

12/01/2001


KEY WORDS

 

  • Motors, drives, & motion control

  • Distributed control

  • Mechatronic systems

  • Servo, brushless, and step motors

Sidebars:
Growth rate quickens for intelligent, integrated servo drives
Linear motion also integrates intelligence
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An emerging class of motion control products—that combines motor, drive, controller, processing intelligence, feedback device, I/O points, communication, and more in one package—defies simple naming. Some systems add all the elements to the motor, others only a few. Integrated, intelligent motor and control (I2MC) unit is the tag name used here, although some of the systems covered are heavier on integration than intelligence. The definition of "intelligence" is often in the eye of the manufacturer.

Capabilities of the technology range up to multi-axis coordinated motion, CNC path profiles, and precise positioning of loads. Widening applications run from assembly, material handling, and packaging systems to robotics and semiconductor production.

The I2MC approach promotes distributed control. At the same time, it requires more discipline to implement, with up-front planning and design of the overall system architecture. Reasons for integration are to eliminate the need for separate control enclosures, reduce wiring between motors and controllers, minimize electronic disturbances from long cable runs, and lower system cost.

Less obvious is the possibility to build scalable systems, explains Eric Dunn, P.E., director of marketing at QuickSilver Controls Inc. (QCI, Covina, Calif.). For example, if a four-axis motion system has to be expanded to six axes, a second four-axis controller would likely be added to a traditional design. This is more costly than simply adding two integrated servo axes.

QCI asserts that installed cost of an I2MC package is less than a servo axis of equal power built from traditional components. Applications where compactness or control space has no great value provide an exception. Installed cost includes hardware, wiring, assembly time, and controls enclosure (including cost of space it occupies).

Siemens Energy & Automation (Alpharetta, Ga.) also notes significant cost and space savings in eliminating a separate control cabinet. Moreover, only two cables (power and communications) are needed to operate an integrated system, explains John Krasnokutsky, product manager, general motion control drives at Siemens E&A. And for additional motion axes, the cables are easily extended in daisy-chain fashion.

Total (installed) cost favors the integrated design in Siemens' view because of much less wiring and use of low-voltage 24/48 V dc input.

I2MC product manufacturers agree that integrated systems are less costly than standard units of similar size and power.

Slow to take off

Robb Dussault, motion marketing manager at Schneider Electric (North Andover, Mass.) views mechatronic integration as an evolving process that has come into its own only within the last decade. On the electronics side, microprocessors and digital signal processors (DSPs) had to be available with capacity to add meaningful intelligence, for example, to do motion path planning.

Even with clear industrial benefits, the shift to newer technology proceeds slowly, reminds Mark Olton, Schneider Electric business development manager for motion products. "Real or recognized need promotes the acceptance of new technology; otherwise a 'don't fix it, if it's not broke,' syndrome takes over," he adds.

Reasons for slower-than-expected uptake of this technology range from resistance to changes by users comfortable with existing products to a few legitimate limitations, according to Robert Bigler, president and ceo of Animatics Corp. (Santa Clara, Calif.). In between are misconceptions about I2MC packages, such as susceptibility to heat, electrical noise, and vibrations. Mr. Bigler doesn't consider these concerns legitimate, citing the accepted practice of integrating encoders with motors in many industrial uses.

He offers this rule of thumb: "Integrated servo systems are probably not a fit where resolver-type feedback is required, as in excessively hot, explosion-proof, or nuclear applications."

Animatics, a pioneer in integrated servo-positioning systems, has patents and products dating back to 1994. Today, it has probably the widest product line up with its SmartMotor available in NEMA 17 through 56 frame sizes. The latter unit produces about 10 horsepower peak output.

Still, an overall relatively low power range has limited the use of I2MC technology to date. At Siemens E&A, focus has been mostly on other higher power drives. Its integrated servo positioning system, Simodrive Posmo A, delivers two output levels: 75 and 300 W at 24/48 V dc, respectively. Various gearboxes can multiply torque output. The motion controller includes speed, position, and current loops. Posmo A ("positioning motor"), released in North America in January 2001, had been available in Europe much earlier. A higher power unit, Posmo SI (servo integrated), is coming in January 2002. It will be rated from 1.9 to 5.7 kW and run on 600 V dc supply.

Schneider Electric's Mr. Olton also thinks I2MC products' relatively low power output is an inherent limitation to wider use. While larger units are possible, the basic advantage of space and cost savings is lost as size of the amplifier package grows. "We can't expect to solve all applications with one approach," he says. Of course, maximum size varies considerably from supplier to supplier.

Mr. Olton doesn't consider heating effects detrimental to the control electronics for the usual unit sizes and "normal" duty cycles. However, heating effects could be a concern for larger sizes and power outputs.

Schneider Electric's product offering is Telemecanique IclA (integrated closed-loop actuator), a servo-positioning system intended for OEMs, networkable via CANopen (bridges to DeviceNet and CANbus). Sold in Europe since 1999, IclA drive has been available in the U.S. in 2001 on a project basis and heads for off-the- shelf stocking in 2Q02.

Until recently, processors, memory, and other elements needed to support I2MC systems had limited capability or high cost, according to Mr. Dunn of QCI. Much improved power of today's ever-smaller processors widens the possibilities. New applications favor these integrated units versus retrofits, because designers can better adapt them to a plant's total control architecture, he explains. QuickSilver Control's product line is the SilverMax family of NEMA 17, 23, and 34 models, including IP65 washdown option. SilverMax uses stepper motor topology that operates under closed-loop servo control.

Some other I2MC products include Milan Drive from Werner Riester GmbH (Ostfildern, Germany) that integrates an ac servo motor, amplifier, microcontroller, resolver, I/O points, and various options; "Benjamin," a combination of an ac servo motor, drive, encoder, and communications in a lower-power product, from Andrive Antriebstechnik GmbH (Bremen, Germany); and Bodine Electric Co.'s (Chicago, Ill.) IntegraMotor, that combines a brushless dc motor, drive, Hall-effect feedback, and gear reducer (on some models).

Most integrated products feature serial communication (RS-232/485), with other network buses as an option. European products tend to include a network bus as a standard offering. Operator-interface options include a PC, PLC, touch panel, liquid crystal display, etc. More detail on products and operator interfaces in an Online Extra article at www.controleng.com .

Not for everyone

Integrated motor/controller technology has its limits—real and perceived. Mr. Dunn thinks the compactness conveys a "smaller is less" image to customers despite the great functionality contained in a small volume. The current handling capacity of these units can also mislead, thanks to remarkable advances in MOSFETs (metal-oxide semiconductor field-effect transistors).

Mr. Dunn points to real limits of the technology in extreme environmental conditions (high-temperature, explosion-proof), lack of specialty motors (ultra-high speed), and a practical top end of power output. As motor size grows, space and cable savings diminish. Size of the controller and onboard power supply increase as well. He sees integrated motor/controller units mainly in new applications, not retrofits.

Animatics' Mr. Bigler mentions that an integrated servo system is often unfairly compared with only the servo motor part of a traditional system. Actually, the integrated motor "grows" a little larger and heavier due to the embedded controller, internal connections, and thermal management requirements. This eliminates its application in some highly weight-sensitive robot arm systems, he says. "Yet, the integrated design offers the highest torque density available, when compared as a complete system to a traditional servo approach."

Rallying 'round steppers

Some manufacturers choose to integrate their motion control systems around stepping motors, which offer low-speed torque superior to servo motors of equivalent volume, as well as simpler controls. The downside is the step motor's quite rapid drop in torque at higher speeds. Examples of step-motor-based-systems follow.

Whedco (Ann Arbor, Mich.), a subsidiary of GE Fanuc Automation, refers to its Stepping Motor Cube as a "space conscious, high-performance" device that fits into applications with scarce panel space. The Cube operates in traditional open-loop mode, and consists of an integrated controller/ amplifier, NEMA 23 step motor, and DeviceNet connectivity in a compact package.

Recently, Whedco added a stall-detection feature to Stepping Motor Cube. The sensorless method monitors and alarms the occurrence of stall, eliminating an encoder, extra wiring, and complex programming. To allow tuning of stall detection to a given application, the algorithm uses three configurable parameters—stall velocity threshold, stall sensitivity, and bus voltage. These parameters can be accessed via implicit I/O and explicit messaging protocols of DeviceNet. The Cube can detect stalls in position and velocity operating modes.

A NEMA 34 "Cube" is in development and will be available in 2002.

Intelligent Motion Systems (Marlborough, Conn.) has integrated a NEMA 17 and 23 step motor with drive electronics in one package. Configurations include an optical encoder. Operating from low dc voltages, MDrive 17 (12-48 V dc) and MDrive23 (12-24 V or 24-75 V dc) offer design simplicity; microstepping (1/2-256 microsteps/step in up to 14 resolution settings); and speed control that now includes 0-5 V dc, 4-20 mA, and PWM inputs.

Sonceboz SA (Sonceboz, Switzerland; Plainview N.Y.) integrates step motors or linear actuators with power electronics, control processor, and sensor/ control interfaces in its 8000 Series Mechatronic Systems. Multiple units can be coupled via CAN, serial bus (RS-485), or other data networks. In connection with this product, Sonceboz offers a system concept called Dynastream, said to optimize performance parameters in a specific motion application.

Networking, smaller units ahead

According to Schneider Electric, intelligent servo products' growth will depend heavily on the progress in networking of motion systems. Other driving factors listed by Mr. Olton are potential savings in machinery control spaces, cabling, and installed cost.

QuickSilver Controls sees usage of integrated servo technology growing in the next few years. It will push forward using the same tools as traditional servo systems—advanced drive electronics, faster processors, and smarter bus/network structures. In a shorter timeframe, higher level buses (CANbus, DeviceNet, Ethernet, etc.) and coordinated motion are being added.

Expansion to sizes larger than NEMA 56 frame (or equivalent) is another story. Customers are not demanding such larger sizes, according to QCI's Mr. Dunn. However, development toward the small end is expected. Size 11 integrated servos can be expected before long, as soon as encoder resolution and other space-sensitive design challenges are met. "The market for smaller sizes is out there," he concludes.

Siemens E&A sees increased interest in integrated servo positioning systems, especially in Europe. "Because Posmo is so new to the U.S. not many potential users are aware of it or the ease of implementation it can offer," says Mr. Krasnokutsky. "It's another case of the need to get the word out on how and where to apply these products. A change in mindset is needed." He predicts size and power growth for the technology.

Animatics also attributes a bright future to I2MC systems. Less costly, but more capable and temperature-tolerant microprocessors plus the growing power of MOSFETs and power modules are the driving forces that parallel integration trends in other areas. "Integrated servo positioning systems will ultimately take 100% of marketshare in their size range," states a most enthusiastic Mr. Bigler, without giving an exact time frame. "In this most elegant design, the integrated servo system knows exactly the motor's temperature, voltage, and current flow status," he adds.

With few requests for higher power applications, little growth is seen above present unit sizes. However, "smaller" is more in fashion. Animatics' has designed a NEMA 11 system and seeks customers.

"Increased growth for these new 'mechatronic' drives is on the horizon, despite their limited use to date," says Mr. Kaporch of Drives Research Corp. "An expected rise in demand for intelligent servo drives will occur as PC-based and network-based distributed control and communication architectures find larger roles in factory automation and other applications."

Look for integrated, intelligent motor and controller packages in your future, perhaps for your next design or purchase.




Growth rate quickens for intelligent, integrated servo drives

Intelligent, integrated servo drives account for less than 1% of today's $4 billion-plus total servo drive market worldwide, according to Tom Kaporch, president of Drives Research Corp. (San Juan Capistrano, Calif.), a market research firm specializing in motors and drives. "Yet, more than twice the growth rate of the overall servo drive market is expected over the next five years and even a higher rate thereafter." This means a compounded annual growth rate of more than 11% over the next five years.

Drives Research Corp. notes three emerging trends that put intelligent integration into perspective:

Combining the servo amplifier with drive logic in an integrated—not modular—electronic package accounts for under 30% of the total market;

Embedding a motion controller (intelligence) in the electronic drive makes up less than 10%; and

Integrating the motor and electronic drive accounts for less than 1% of the total.

Mr. Kaporch's modest figure for intelligent, integrated systems refers to only high-performance "servo drives" (motor and electronics) capable of dynamic response. For non-servo brushless motor drives—used, for example, in automotive applications—the rate of motor-drive integration is around 8%, and growing fast, he explains. For more about these applications, see the Online Extra at

Intex Management Services Ltd. (IMS, Wellingborough, U.K.) reports roughly similar market figures from its European-based research on "servo motors with an integrated drive." IMS quantified the European market size for these products in 1998 at $3.3 million, growing to around $8 million by 2001. In an August 2001 IMS study on the total servo market, North American market size for integrated products was "less clear...due to the small number of domestic players," says Adrian Lloyd, director of IMS' U.S. Industrial Group (Austin Tex.). However, Mr. Lloyd estimates this market to be less than $10 million today.

Further surveys of user attitudes by IMS reveal substantial interest in future usage of these products in Europe as well as the U.S., albeit "in relatively low volumes." IMS sees a definite trend toward more applications, but expects integrated servo motor and drive units to remain a market niche. One underlying factor is the present lack of interest by most major manufacturers. (More online at

At the same, integrated servo motor and control unit manufacturers are confident about existing and prospective markets.

Linear motion also integrates intelligence

Integrated intelligence is no less in demand when linear motion is the desired output. A bit of simplification in the linear world comes from the actuator design that includes a support structure for bearings, ballscrew, or other rotary-to-linear motion converter, providing some space to integrate extra elements.

Adept Technology Inc. (San Jose, Calif.), is one company pushing both integration and intelligence into its flexible automation systems and robot products. Adept has integrated a power amplifier and motion controller into its newest SmartAxis family, which, in turn, is packaged into a self-contained single-axis linear motion module actuated by a servo motor. Smart-Axis needs only control signals and power input to operate. The motion controller—located in the amplifier rather than the motor—delivers trajectory planning and advanced servo-loop control using a DSP that runs an embedded subset of Adept's V+ robot programming software, explains Joe Campbell, vp of marketing.

"The idea is to collapse the controller and CPU functions into the amplifier, then onto the mechanism," says Mr. Campbell. "This design saves cabling space, which becomes very costly, especially for robotic cells."

For multi-axis linear motion (2-4 axes), Adept offers SmartModules that integrate servo motors, power electronics, and servo processing into the unit. (For more, see Online Extra at

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Go to

I2MC markets

Other suppliers:

Colibri/Mesa Systems

Mitsubishi Electric

Myostat Motion Systems

Pittman

Operator interfaces

Products table



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