Frank J. Bartos, Control Engineering

Proximity sensors shine on the shop floor

Sensing the presence or absence of objects, liquid levels in clear containers, or counting cans moving down a conveyor pose everyday tasks for discrete sensors on the factory floor. Noncontact proximity sensors form one branch of discrete sensors, with capacitive, inductive, photoelectric, and ultrasonic devices in common use—each differing in the sensing method.

Automating Your Packaging Lines

Though it's not a new development for the large variety of packaging machines that produce myriad packaged products, automation now offers a whole new level of packaging productivity. Much of prior automation was limited to an architecture where a large mechanical line shaft, driven by a main motor, powered devices and actuators to accomplish various packaging functions.

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...

Motion Simulation Cuts through System Development Uncertainty

That new prototype actuator mechanism is complete. Weeks of design work, machining intricate parts, and assembling a complex motion system are happily at an end. The innovative design checks out on paper, and in CAD. Its physical package looks sleek and compact, as well. Yet, upon testing the actuator it doesn't accelerate fast enough or deliver the required force at the end of its motion.

Motion System Simulation Pays Off in Many Ways

Online Extra to August 2001 Control Engineering article on 'Motion Simulation.'

Efficient Motors Can Ease Energy Crunch

KEY WORDS Motors, drives, & motion control AC variable-speed drives AC induction motors Energy-efficiency Just glance at some recent headlines about energy costs and power shortages. Never has it been more timely to implement prudent use—not repressive use—of electric energy. Electric motors in general, and industry's "workhorse" ac induction motors in particular, represent g...

Energy-efficient motors may now get respect

M aking electric motors more efficient has never had greater incentive than today. Recent realities of energy costs and supply problems underline the need to act. Electric motors consume over 60% of all electricity used by U.S. industry.

Combination Motors and Drives Move to Make their Mark

E lectric motors and their control electronics were not created as equals. So it's not a coincidence that until recently they operated in separate locations, connected by often lengthy and costly wiring for power, control, and communication. Electronic controls generally reside in safer, cooler, and more centralized enclosures, while motors face more severe conditions of temperature, humidity, vibration, dust, washdown cleaning, and more, found in the industrial world. In the last decade, however, the two technologies converged and time became 'right' to unify a range of motors and drives.

`Soft Motion’ Follows Nontraditional Paths

M otion control finds itself, increasingly, an intimate part of the overall machine or process control system. As such, motion control is often associated with PC-based control that relies heavily on software functions. Soft motion is an emerging subset of PC-based control-similar to the development of soft logic-where motion control functions execute in software, entirely on the CPU of the industrial personal computer. Soft motion is characterized by the absence of proprietary hardware or motion control boards.

Rotary encoders provide variety

T he most common feedback device used in motion control systems is the rotary optical encoder. Comments in this 'extra section' pertain to that encoder type. Typical encoder applications encompass machine tools, web handling equipment, robotic and vision systems, packaging machines, conveyors, gantry cranes, storage and retrieval systems, etc. As mentioned in the main article, a standard way of increasing an incremental encoder's resolution is to count the leading and trailing edges of the quadrature signals generated.

Step Motor Systems Battle for Motion Control Market Share

Satire is much in vogue in magazine ads. For example, dinosaurs have served to differentiate what's "in or out" for distributed control systems. Even step motors are not immune from satire, as in one servo system advertisement of a few years ago that referred to step motors as "great boat anchors.

Step Motor Systems Have a Lot to Offer

S tep motors and controls continue to evolve and innovate. In their long-standing competition with servo-based motion control, some stepper system developments surprise the users. Stepper drives incorporating digital signal processors (DSPs); common control units for both step motors and servo motors, selected through software; methods to monitor or control step motor stall; and a growing integration of functions around the step motor are some topics discussed in the main text article . Here is additional coverage on these and related areas. Alignment pins and a locator dowel on the front face of Empire Magnetics' Size 11 Medical Motors help personnel wearing rubber gloves with equipment assembly in a sterilized environment. Slow-speed disturbances have been a problem area for stepper systems in the past.

Hannover Fair Leads the Way to Expo 2000

How quickly another edition of "the world's largest industrial fair" rolls around. And this year it's no illusion because the fair comes a month earlier than usual—part of rescheduling several shows to accommodate Expo 2000, the World's Fair, starting its five-month run on June 1, in Hannover, Germany.

Several Shows on the Program at Hannover Fair 2000

T his year's Hannover Fair offers visitors an integrated combination of six exhibition sectors. Besides the core Factory Automation sector covered in some detail in the main article, here is a further look at the other exhibit sectors available to control engineering practitioners during this March 20-25 event. Other fair sectors Materials Handling & Logistics (Halls 19-26 and open-air site) is the second largest show sector in terms of display area. In fact, its technologies overlap somewhat with factory automation.

Medium-Voltage AC Drives: Addendum and Applications

M edium-voltage (MV) ac drives take over the scene at voltage and power levels beyond the capability of more familiar low-voltage (LV) drives. These larger MV drives-with power ratings to 100 MW and over-bring the benefits of adjustable-speed operation to large ac motors. A further benefit they offer is soft-starting of such large, expensive motors (see application section, below).

Medium-Voltage AC Drives Shed Custom Image

Where do you find control solutions for the largest industrial- or power-plant-type loads that require multi-megawatt electric motors to power them? Today, one growing technology option is the medium-voltage (MV) ac drive. MV drives are similar to, but hundreds of times larger than, their more common low-voltage (LV) cousins.

AC Induction Motor Designs, Types

W orldwide popularity of ac induction motors in numerous applications has led to some standardized motor designs. Concentration on a finite number of motor types also brings design and manufacturing efficiencies, while helping to achieve attractive pricing. The National Electrical Manufacturers Association, (NEMA, Washington, D.C.) has developed specifications for so-called NEMA design A, B, C, and D motor types. These designs are based on standardizing certain motor characteristics such as starting current, slip, and specified torque points (see below).

‘Forward to the Past’ with SR Technology

A rugged, low-cost brushless dc motor technology without magnets, readily available for use! Now there's a bright new idea. Bright yes, new no. At age 150 years plus, and counting, switched-reluctance (SR) motors represent one of the oldest electric motor designs around.Simple construction is a prime feature.

Interkama ’99 Resumes Its Lead Role for Process Automation

A technological "Watch on the Rhine" of giant proportions will be staged in Düsseldorf in mid-October, when 80,000 worldwide visitors are expected to partake of the latest offerings of 1,500 exhibitors and two extensive conferences at "the world's number one international trade fair for measurement and automation technology.

PM Servo Motor Size Perspective

S upply usually meets demand. It's not too different in the world of high-performance electric motors. Demand for permanent magnet (PM) synchronous servo motors has traditionally been in the lower power ranges. This went hand in hand with the majority of applications that had limited power needs.

Servo or Vector Control Can Handle Many Applications

This article, Part 2 of 2, looks at applications. Part 1, in February (March International issue) provided an overview of the two control methods. Applications in printing, converting, and web handling are among areas of competition for servo and vector control, two distinct motor-control methods.

Predictive Maintenance Widens Its Acceptance

Predictive maintenance is the most sophisticated of industrial maintenance and asset management techniques. It's an evolving, forward-looking method that combines hardware elements--for sensing and collecting information about equipment operation--with software elements for analyzing and managing the data. Actually, predictive maintenance employs a collection of nondestructive methods to do its work; for example, vibration analysis, oil wear particle analysis, infrared thermography, various electric motor circuit analyses, motor parameter monitoring, etc. Predictive, more than preventive Sophisticated numeric analyses then go on to estimate machine health and predict remaining life of equipment, using historical as well as operational data.

Predictive Maintenance Maximizes Machinery Health

As the name implies, predictive maintenance anticipates equipment outages rather than reacting to them. Benefits include fuller useful life for equipment and lower backup inventory. It goes beyond preventive maintenance, which at least strives to shift plant downtime to noncritical periods. Initial cost of predictive monitoring systems tends to be high, but much less than forced reactive ...

MIMOSA Cuts through the Information Maze

Making sense of masses of machine-condition-related information is a daunting task. The Machinery Information Management Open Systems Alliance (San Diego, Calif.) was formed for this purpose and to promote a broad industry initiative for generating basic equipment performance and operational data. MIMOSA consists of both suppliers and users of instrumentation and maintenance information management technology. It is a nonprofit corporation of over 50 companies and 200 individuals worldwide--and growing. MIMOSA advocates open exchange of equipment-condition-related information among condition assessment, process control, and maintenance information systems.

Motion Control Tunes into AI Methods

Techniques include such names as fuzzy logic, artificial neural networks, genetic algorithms, and expert systems. "Artificial intelligence" (AI) is the family umbrella that loosely links these techniques and separates them from traditional computing methods. Each mimics some aspect of intelligence—human problem solving, learning, knowledge, or evolution.

Linear Motors and Controls

This section contains additional information related to Control Engineering 's April 1999 article on Direct-Drive Linear Motors and Controls. A table of linear motor products appears in the main article, while representative linear control products are tabulated at the end of this section. Linear motors in machine tool systems require real development process While it's getting simpler to use linear motors, their successful application in machine tool/computer numerical control (CNC) systems still requires a thorough development plan. Complete integration of machine and motor is vital.

Linear Motors and Controls Seek the Mainstream

Hardly new as a technology, direct-drive linear motion systems show a growing variety of configurations. Motor and load are directly connected—as the name implies—doing away with gear trains, belts, ballscrews, and pulleys to achieve remarkable speed, precision, and reliability. Linear motion systems shine where performance is crucial.

Vector Control Competes with Electric Servos

This article (Part 1 of 2) compares technologies and looks at selection guidelines. Part 2, in September, will explore applications. Once upon a time…electric servo systems using permanent magnet (PM) synchronous motors represented the ultimate in high-dynamic position and torque control.

Power Management Helps Your Plant ‘Live Long and Prosper’

Management of industrial power means many things to many people. Available technology ranges from increasingly sophisticated devices that meter power consumption, monitor quality, or provide emergency backup, to full systems able to do all that plus overview usage of power for efficient production and diagnose and possibly prevent outage problems.

Enhancements Help Step Motors and Controls Evolve

In their traditional open-loop operating mode, step motors and drives remain the simplest, most economical means of position and motion control for a variety of industrial applications in the power range up to one horsepower (0.75 kW). Simple control, yes, but the step-like motion can introduce resonances plus other disturbances over a motor's operating speed range.

Motion Control Sails into a Sea of Applications

Industrial applications represent the mainstream for motion control, but recent spectacular examples from the "entertainment industry" are hard to ignore. In-deed, applications in the cinema, stage, amusement park rides, and other visible venues continue to push motion technology's envelope.One notable example from the entertainment field is "Masquerade Show in the Sky.

Electronic Motion Control Reaches for the Sky

Electronic motion control has become a complex combination of diverse elements—motors, drives, amplifiers, motion controllers, embedded chips, feedback devices, software tools, and more. This vast mosaic of solutions is supplied by hundreds of companies with new entrants expanding the list.

Efficiency to the Masses —of Electric Motors, that Is

Energy efficiency is hardly a new theme. In a technologically expanding world, it has become crucial to come to grips with energy consumption yet still use energy wisely. A basic question to answer is, "Where can energy be saved efficiently"?Electric motors, particularly in industrial usage, represent a large portion of electric energy consumption.

Motor Starting and Protection Moves Closer to the Process

Your industrial electric motors are in good hands. Motor starter devices and systems provide all the functions necessary for safe starts and stops. They protect against current overload, under voltage, over voltage, short circuit, phase loss, ground fault, etc. Newer products—especially microprocessor-based ones—add more motor protection, diagnostics, and the ability to commun...

Hannover Fair ’98 Goes More Global Than Ever

Start the second 50 years! Hannover Industrial Fair begins its second half-century after a long, successful run that began under quite humble circumstances. This "world's largest industrial trade fair" arose from the post-World War II ravages of Germany.As Hannover Fair faces its second half century, more changes are certain due to economic and technology trends.

AC Microdrives Ply Parallel Paths

Despite the temptation, size alone is not the right descriptor for ac "microdrives"—those ultracompact variable-frequency drives (VFDs) that sprouted during the first-half of the 1990s. For quite a while, it seemed, each new model would be even more miniature than the one announced just a month or so earlier.