Industrial Machine Design: Leap of Faith?

Technology trends don't always lead to better machine design, but CONTROL DESIGN's Senior Technical Editor Dan Hebert found a few that could help you break away from the crowd.

By Dan Hebert

August 2004, cover imageWe all sometimes think of ourselves as independent, "I gotta be me" captains of industry. But the direction of business is constantly affected by external market trends, some inevitable and overwhelming, others subtle and infectious, but all emerging to shape change. Sometimes this influence happens whether we like it or not. Sometimes, it's when we're smart enough to catch on early and ride a wave of disruptive technology.

 

What follows is our forward-looking view of machine builder industry trends. In it we look at how advances in automation, instrumentation, and electrical technology are likely to affect you and the direction of business. Some of the trends we cover are the direct result of vendors addressing OEM needs, while others are external influences that must be addressed by OEMs.

Some of the trends we identify probably are no great surprise to any of you. Others might be accelerating into the market faster than you think. Regardless, they all are having significant influence on the way our industry strives to improve machine performance, reliability and versatility

While there's bound to be disagreement when selecting a short list of mighty technology trends, in our minds, these are the ones likely to make the biggest impact:

  • Integrated hybrid control platforms,
  • Real-time machine vision,
  • Global standards,
  • Wireless network infrastructure,
  • Distributed machine control,
  • Machine safety, and
  • Servo motor/drive deployment.

Many Functions, One Platform
Machine functionality often includes a need for discrete, analog and motion control capabilities. Until recently, this meant integrating multiple controllers. Hybrid controllers now are available that can perform all needed control functions with one integrated platform.

Hybrid controllers are capable of at least two of these types of control: discrete (on/off), analog (process), and motion. Hybrid controllers are not special-purpose controllers, because the latter can only perform one type of control. Typical special-purpose controllers are small PLCs (discrete), single or multiloop PID controllers (analog), and motion-only controllers.

At this point in market evolution, virtually every PLC vendor offers hybrid controllers capable of discrete, analog, and motion control. Most loop-control vendors offer products that also can perform discrete control, but motion control is not addressed within this product class. Motion controllers that perform discrete and motion control are now common, and it's possible to find motion controllers with analog process control capability.Given the state of today's market, controller selection now is driven by specific application characteristics rather than device characteristics.

One of the main applications for hybrid controllers is motion control coupled with discrete and/or analog control. Two main types of products compete in this market space: motion controllers with discrete and analog I/O plus logic, and PLCs with motion control capabilities.

R.A. Jones Inc., best known for its line of high-volume packaging machines, has been performing a complete range of turnkey design and integration services for more than 25 years. The company uses hybrid motion controllers because "hybrid control streamlines the control architecture by removing the logic needed for handshaking between the motion controller and the discrete controller PLC," says Darren Elliott, chief engineer of Jones' electrical controls group. "This means less logic, quicker scan times, less hardware and less wiring. Reliability is better because there are fewer points of failure, and startups are quicker because there is less debug time and because hybrid controllers are easier to troubleshoot. It is also simpler to integrate advanced, time-critical functions such as registration when motion and I/O information are controlled uniformly into one central processor."

Because many industrial OEMs associate PLCs with discrete control only, new terminology is being used to describe hybrid controllers. "We see a trend towards the convergence of control disciplines into a single, multi-discipline controller," observes Rick Morse, manager of strategic applications for Rockwell Automation.

The Vision to Control
Machine builders and customers have long supplied and used automated vision systems for off-line inspection. Lately, the use of vision inputs for real-time control is gathering steam as an industry trend.

Several technology advances are acting simultaneously to improve vision system performance in real-time control applications. A smart camera not only is faster, smaller, and cheaper than its dumb cousin; it also is easier to interface to real-time controllers. As with hybrid controllers, more vendors are making control of functions such as motion and vision an integral part of their control systems.

Palomar Technologies, Vista, Calif., upgraded a manual microscope targeting system to a fully automatic operation guided by machine vision. Palomar manufactures precision assembly systems including die bonders and wire bonders for customers in the wireless, photonics, defense and hybrid semiconductor markets. One of the most important design decisions for an industrial OEM using machine vision for real-time control is speed versus flexibility.

"Opening up the process window to enable multiple part orientations or to recognize same-function parts from different vendors enhances program flexibility and reduces rejected parts, but may add costly time delays," says Eddie Wills, product manger for component assembly systems with Palomar. "Our integrated control and vision systems provide our customers with the ability to optimize their process window decision."

Stress Engineering Services of Norcross, Ga., also used a machine vision system to replace a manual system that relied on microscope targeting. Its vision and motion precision integrated robot uses a National Instruments vision system to perform edge detection and part position determination in the alignment process used in assembly of optoelectronic devices. These applications typically require sub-micron positioning accuracy.

According to Mark Bennett, PE., principal with Stress, the primary benefits of the machine vision system are higher quality products, a lower level of operator involvement, and higher reliability. Bennett says image processing continues to consume a great deal of computing power, and he would like to see improvements in the efficiency of image-processing routines along with improved lighting tools.

Pemstar, Rochester, Minn. uses vision system inputs to provide real-time closed-loop motion control for an adhesive attachment cell (see Figure). The cell is used to align and attach components. Before the vision system was integrated into the cell, calibration of adhesive volume and position of the adhesive dispense system was done manually.

The vision system not only improves process quality, it also reduces the cost of other cell components. "Using the vision system to close the loop allows the motion control system to be lower cost," says John Martin, director of precision automation at Pemstar. "Adhesive calibration with the vision system enables faster and more repeatable dispenser set-up. On-line measurement of alignment allows real-time control over the alignment distribution."

Robotic systems now use machine vision to close the control loop. Western Digital (www.wdc.com), San Jose, Calif., uses a Cognex vision system to locate a hard disk head stack assembly in a backlit shipping tray. A robotic gripper uses this location information to pick up the assembly and move it to a hard drive base. The robot/vision system replaced a manual operation, resulting in a substantial speed increase and a reduction in labor costs. According to Andrew Klassen, Western Digital's senior principal engineer, the system can operate in normal factory lighting conditions because the camera filter is only sensitive to the red backlight under the shipping tray.

Resistance Is Futile
The first two trends are largely a response by vendors to industrial machine builder needs. The next trend is a result of outside influences that, like it or not, dictate industrial OEM actions. As the world globalizes, machine builders are selling more to customers outside of North America. These customers often demand compliance with their own regional standards, and industrial OEMs must comply.

Alliance Machine Systems Intl. has to cope with demands from overseas customers. Alliance designs and builds material handling equipment for the corrugated box industry.

"Meeting international standards and regulatory standards is a definite trend and a huge challenge for us," says Mike Harrington, PE, director of engineering at Alliance. "Unfortunately, many components of our control and safety systems change depending upon the country of the customer. Our goal is one common hardware and software design so any of our customer service personnel can install, maintain and service equipment regardless of its country of origin."

It's a struggle to interpret local codes, so maintaining common drawings sets and part databases world-wide is a struggle, even in countries that supposedly use the same codes." In European Union countries some of our machines require different solutions even though all EU members are supposed to accept machines that are CE-certified," laments Harrington. The problem arises, he says, because codes are enforced by local inspectors who want things to agree with their interpretation. Clearly industrial OEMs don't want to make different products for each region, so there is a real need for international standards.

Many European standards have been a precursor to international standards, and this is a welcome trend. But, according to Harrington of Alliance, the trend needs some clarity.

Another problem with international acceptance of machines has nothing to do with standards. It concerns local languages. This can affect everything from HMI displays to labels and documentation.

Many HMI programs have automatic translation capabilities, but these translations must be carefully reviewed by experts proficient in both machine operation and local language. Translations made directly by software tend to produce garbled language similar to that one finds in fortune cookies and operating instructions for cheap toys.

Garbled operating instructions for toys are usually nothing more than an amusing distraction, but machine operating instructions need to be more precise.


 

Around the Bend 
Our research revealed a few emerging trends that, while not significantly impacting machine automation today, are likely to grow in influence in coming years.

 

FPGAs in Real-Time Control
Recent improvements in field-programmable gate arrays (FPGAs) have created a viable method for machine builders to create their own silicon-based controllers
 
The advantages of creating a custom silicon-based solution are amazing gains in speed, astounding cost savings, and incredible reductions in size, power consumption and heat generation. These gains come about because it is often possible to replace an application-specific integrated circuit (ASIC) chip, a printed circuit board, or even a board set with one FPGA

Most FPGA programming is done with a hardware description language called Verilog. While Verilog is fine for chip designers and programmers, it is somewhat arcane for most machine control needs.

National Instruments provides tools to simplify FPGA programming. "After writing an FPGA application using normal LabView programming techniques, the code is automatically compiled to synthesize digital logic and downloaded to the FPGAs," says Brian MacCleery, industrial control and measurement product manager with NI.

In addition to processing I/O signals, FPGAs mounted on combo I/O boards with inputs and outputs are being used to create full custom silicon-based controllers with unprecedented processing speed and lighting fast execution times.

Smart Cell Phones Conquer Mobile Computing
Mobile phone sales to consumers topped 510 million units in 2003 and will exceed 560 million units in 2004. Worldwide shipments of smartphones, rose 182% in 2003 to 9.6 million devices. Smartphones feature calendars, email, pictures, music, and other services in one device.

These quantities mean that cell phones in general and smartphones in particular eventually will come to dominate the market for wireless monitoring of industrial machines.

At present, there are a myriad of handheld devices that can be used for wireless SCADA monitoring including PDAs, portable PCs with wireless connectivity, and cell phones. But PDA sales are dropping because of smartphone pressure, and it is hard to envision a future where portable PCs will compete with the price pressure.

Of course, the line between smartphones and PDAs are blurring, but the bet is that future mobile wireless devices will look a lot more like cell phones and a lot less like PDAs.

In the near future, smartphones will have a host of built-in features including global positioning, RFID tags, video recording, digital imaging, web access via browsers, e-mail send and receive, and corporate intranet access via Virtual Private Networks (VPNs).

Economies of scale mean that it will soon be feasible to equip all plant personnel with a $100 or less smartphone. Machine monitoring applications will be limited only by the imagination of end users.