This technical information has been contributed by
Orchid Technologies Engineering and Consulting, Inc.
There's no Room for Error When Designing Controllers for Mission-Critical Industrial Equipment
Design Firm Uses Low-power, Low-cost processors for High-tech, High-function Industrial Control Apps
By David Gaines
Associate Editor, Design-2-Part Magazine
A leading-edge hardware and software development company operating out of Maynard, Massachusetts, regularly creates robust, customized programmable logic controller (PLC) technology to assist end users in their quest to scale high industrial control mountain tops. During one customized PLC project, the company--Orchid Technologies Engineering and Consulting, Inc.--designed and engineered a cryogenic vacuum pump controller that replaced thousands of dollars worth of general-purpose PLC equipment.
The vacuum pump's single-circuit-board, custom controller- based upon a low-cost processor architecture-- provided RS232 communications, network communications, real time clock services, AC motor control, AC heater control, two cryogenic temperature sensing channels, two low-pressure sensors, and general purpose inputs and outputs. In addition, the design firm was able to create custom programming to operate complex pump control sequences that included purging, regeneration, temperature control, and error detection. The single-board controller is housed in a small, waterproof NEMA-rated steel box to protect the interior electronics.
Design and manufacturing engineers have been using PLCs for many years to control industrial devices for applications that include factory assembly lines, semiconductor manufacturing machinery, and automotive component controls. Since the PLC is designed to handle multiple inputs and outputs, it is an ideal solution for electronic equipment requiring many sensors and actuators.
Orchid Technologies (www.orchid-tech.com) is staffed primarily by design engineers that handle prototypes and supervise low-volume specialty manufacturing with the company's manufacturing partners to create a finished product. The firm's 15 years in business have moved it from a small consulting firm to a design, development, and engineering powerhouse, allowing the company to complete a multitude of complex pieces of electronic equipment for a large variety of applications.
The company has been using the Intel® AtomTM microprocessor to formulate hardware and software designs for industrial control applications. "We've been working with Intel® architecture designs for years," says Paul Nickelsberg, president and chief technical officer at Orchid Technologies Engineering and Consulting Inc. "Now that the Intel AtomTM processor is available, it's possible to put high-performance, low-power processors into highly-embedded custom applications. We have some forthcoming programmable logic controller designs that we've been working on, and we have a number of single-purpose controllers that lend themselves to this particular architecture--the operative point being high compute power with very low actual used power. The compute engine requires only two watts, but performs megaflops of floating point numerical calculations."
What Nickelsberg is talking about is desktop class performance in embedded hardware with low-power circuitry. He says it might be in a mobile application, or an application where multiple compute modules might be necessary, or an application where, traditionally, this type of compute performance hasn't been available for industrial controls. The Intel® AtomTM enables Orchid Technologies to put a great deal of computer performance into a very low-power application, and one that can fit into a very small space.
"We've been working on PLC replacement for moving water, which has been very helpful to our client," Nickelsberg points out. "It is low energy, but has a high compute-intensive set of algorithms that we need to run it." -
Orchid Technologies also performs industrial motion control work with the Intel® AtomTM processor, moving large pieces of equipment in a precision manner over large distances. One product hasn't hit the marketplace yet, so Nickelsberg can't say too much about it other than it's used as a motion control device. The company designed the hardware and software for the device, which features a large amount of interface electronics--motor control, sensing, and high-voltage circuitry, as well as software and firmware--to run the entire package.
"We work on all kinds of motion control electronics, from circuit designs to high-powered DC brushless motors and synchronous motors," says Nickelsberg. "A processor such as this offers us all kinds of new possibilities in terms of the motion control work. We can have a number of different channels running on the same machine, which I would say is kind of revolutionary. I think we'll see over the next few years that the AtomTM design lends itself to a lot of places where it wasn't being used before."
Most of Orchid Technologies' electronic equipment projects use either dedicated software or software that can be repurposed. Imagine a number of different channels in a design, all taking their command from a single, powerful microcomputer architecture. The IA-32, Intel's 32-bit processor architecture, allows the company's designers to access all of the existing software available for industrial controls. Another design coming out of the company a while back used the Intel® AtomTM for a notebook computer. Most of the company's work is performed for customized, industrial and commercial products, and the notebook computer application was a venture into the mass-market, general consumer realm.-
Complex, specialized products necessitate customized designs, formulations that often bring added benefits to the marketplace for an OEM. Orchid Technologies appears to be tuned into bringing added value to a client's product from the first spark of the design process. "There are many benefits we offer clients, depending on the product," Nickelsberg adds. "A customized design can be an attractive way to go. It's often for packaging of some kind, or reduced manufacturing cost for that particular client, or for more integrated software. Sometimes it's proprietary functionality that's demanded by a client when they know they can achieve it with their own hardware."
Nickelsberg says that customers often contact Orchid because they have an aging product, or because they've been building a product for a number of years. Some of the parts may have become obsolete, ending the life of an otherwise good product. "A client will come to us and say, 'We have this great product, but we can't build it anymore because these 20 parts are no longer available,'" Nickelsberg explains. "So they ask us to redesign it."
Redesign work is one of Orchid Technologies' strong suits, an area that usually brings added engineering challenges to the conference room table. A redesign project could have the company's engineers designing with any number of different computer processors as the basis for the digital part of the product.
"Sometimes we can redesign a product for someone where the functionality needs to be upgraded, like a product that's still using an 8-inch floppy disk," Nickelsberg says with a laugh. Another style of redesign incorporates modern components to replace older devices, like FPGAs replacing older digital logic. The new design must operate like the old, but in a new way. "There are any number of reasons why a client would want to redesign a product," says Nickelsberg. "A client may say, 'We know it doesn't work right, but we want you to copy the wrongness of it because we're used to that.' It can be a challenge to work with these quirks, but they're usually important to the legacy of the design."
Cryogenic Vacuum Pump Controller Brought Learning Challenges
One critical and complex, leading-edge product--the cryogenic vacuum pump controller--ignited a steep learning curve for Orchid Technologies in measurement, machine control, and science-oriented topics. These demanding applications, however, are the bread and butter of Orchid Technologies' broad array of projects. "At first, we had a lot of learning to do to design for cryogenics, including the nature of cryogenics, the nature of a cryogenic pump, and what it takes to work with things that have physical boundaries," Nickelsberg recalled. "So we learned a lot about vacuum, and specialty temperature and vacuum measurement."
To initiate the project, the firm's engineers had to measure vacuum down to molecules and temperatures into the 10s and 20s of degrees Kelvin. This, Nickelsberg said, was rarefied stuff, so designers had to work very closely with their client to understand the physics of the product in order to not reinvent the wheel. "They had some very particular needs, like sequencing the operations of the cryogenic pump," says Nickelsberg. "It is something that requires about 30 to 50 distinct stages, so we spoke to them quite carefully about it. We allowed them to experiment with those stages, enabling all of us to refine and agree on what we would need to do."
The pump controller was a fast-turnaround project that went from brainstorming to delivery of a first article in 12 weeks, and another 10 weeks to provide final software. Orchid engineers were able to assimilate a large volume of information very quickly, and then start the design process and keep it moving at a rapid rate so that a complete first article product could be delivered in a very short time frame. "We worked very closely with our client, on a day-by-day, and in some cases, a minute-by-minute basis," the company's president remembers. "We had to come up with sequencing steps and actually try them out, working with the equipment and showing progress. We got from here to there in a kind of forced march. It was a very quick turnaround considering we only had three people working on it on our end. Sometimes, however, a few skilled people can move faster than a large contingent of not-so-skilled people. We offer a lot of depth in technology."
Small Design Firm Moves Technical Mountains
Large OEMs will reportedly hire Orchid Technologies because they know that moving mountains and doing it quickly is a challenge that the company relishes. "If a CEO needs a Skunkworks project to get done fast, they'll come to us because we're much more agile," Nickelsberg claimed proudly. "The large companies have a lot of resources, which helps them get things done, but we can move very quickly on a project."
Orchid's pump controller client had very stringent specifications for the product's size, safety, and reliability due to the critical nature of its end use. The client knew exactly what size the device had to fit in, so Orchid had to fit the product's inner electronics into a small, confined space. These exacting size parameters were necessary because the equipment had to sit on top of another piece of equipment. For safety, the pump controller had to comply with basic UL (Underwriter's Laboratory) safety regulations. The biggest challenge, however, according to Nickelsberg, was the reliability issue. "The pump was being used in a production environment, so reliability was utterly paramount," Nickelsberg insisted. "Reliability from the point of view of software use and software testing, and reliability with high mean time between failures."
A part of the design process for the pump controller was to constantly evaluate the device's components, all the while performing excellent design techniques so that Orchid could ensure that the product would work in a production environment for many years without experiencing any technical problems or equipment failures. "Important things were software simplicity and design for reliability, which were of primary concern because the client was so sensitive to these issues," said Nickelsberg. Over a period of several years, about 600 devices were shipped with only two equipment failures. Nickelsberg says that in addition to design, a number of factors contributed to this low failure rate, including the company's robust packaging.
Pump Controller Must Function to Near Perfection in Any Industrial Environment
The pump controller must operate in demanding, high-reliability industrial environments, and has to be able to function equally well in any setting. One common application would be to perform an implant operation on a silicon wafer during semiconductor chip manufacturing. In addition, a cryogenic vacuum pump is imperative for many industrial cooling applications requiring low-temperature physics and superconductivity.
"This controller has to be a very rugged tool," Nickelsberg maintains. "The industrial environment is wet and messy, so we used a waterproof container that was custom-designed for us. The device can be hosed down, it can be thrown across the room, it can be abused in all kinds of ways and not fail. Someone could stand on the device and it will support a grown man's weight, and the electronics inside will not be affected." The need to design a high-quality, fail-safe circuit board for an application as critical as the vacuum pump controller compelled Orchid engineers to formulate a great deal of analysis and testing to be sure that everything would work properly. "Some of it was from the point of view of over-designing the power circuit, and some had to do with doing full FMEAs (failure mode effect analyses) and the operation of the different design elements," says Nickelsberg. "So, by going through an FMEA, one can, in some cases, predict and anticipate certain failures, and thereby design redundantly in order to alleviate them."
To ensure high reliability for components, Orchid's designers used several software checking procedures, including firmware redundancy, self-checking software, and CRC protected data storage. "Self-checking software is a very effective method for ensuring that programs run correctly," Nickelsberg stated. "There are a whole host of things, from simple stuff like Watchdog and CRC, checking that a program is still running, to actual ongoing internal checks for software reliability. Code makes it through master loops or master real-time control processes to make sure every single thing is getting executed."
The crucial end uses of the pump controller require repeated testing at the various stages of operation of a particular piece of code. "For lesser types of equipment, you wouldn't have to do all of these tests," says Nickelsberg, "but it's necessary for aviation, the medical field, the nuclear industry, control software for the chemical industry, and for any industry with critical applications." Critical applications include cases where the failure of equipment would create a life-threatening situation, and where failure of high-cost equipment would be unacceptable. Because of the high costs involved in making semiconductors, for example, failure of the equipment is considered unacceptable even though it's not necessarily life-threatening. "We have done automation controls for the food packaging industry," Nickelsberg reveals. "At the high speed those production lines go, being down for too long can mean millions of pieces of lost production."
Temperature and pressure sensing are integral functions of the cryogenic vacuum pump controller, critical elements that must control cryogenic instrumentation with excellent accuracy. "The temperature sensing is done with a special diode, and that diode is accurate to temperatures in the range of one to 20 degrees Kelvin," Nickelsberg discloses. "The temperature sensing is done based on current in a voltage curve that's calibrated for each one of these. So it's absolutely important to get us to precision temperatures. We're actually able to dial in an operating temperature of 10 degrees Kelvin, and the plus or minus variation is about one degree Kelvin, which is a very tight tolerance."
The Freescale HCS12 processor also had a vital role and provided several advantages for the pump controller, according to Nickelsberg. "The HCS12 processor is very important," he noted. "It's a processor we've worked with a lot, so we're comfortable with its ability to do the job. For one, it has the right mix of math functions necessary, as well as the right amount of I/O and support peripherals. So it, too, worked out to be a very good fit for this application."
As is the case with other custom-manufactured products, requirements for custom electronics vary from customer to customer with respect to overall cost, turnaround time, and product performance. "We work with our clients very closely; therefore, it's more of a collaboration," says Nickelsberg. "In this way, we're sure to understand from the outset what is being asked of us, and we're able to come up with a solution that works well for them."
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