Control Engineering

As I was walking down the corridor at the last Embedded Systems Conference, a man stopped me. “I saw your media badge,” he said, “so I wanted to speak to you about my company GruntWare Inc.”

Zen training has given me infinite patience, so I told him I’d listen to what he had to say as long as he was willing to trot along with me in the direction of my next meeting. This he did while explaining that GruntWare’s whole purpose was to help embedded system designers sort through the huge number of microcontrollers and microprocessors on the market, seeking just the right microcontroller for their embedded control system projects.

This story reminded me that on two prior occasions — blog entries posted on ...Read More

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Don't feel bad about being confused by "medium voltage drives" terminology. It’s a confusing because it sounds like a technical term, but really it’s marketing driven. Actually, there are two terms that can be confusing to anyone new to the field of automated control of electric motors.

Let's start with the word "drive." Also sometimes called an “invertor,” a drive is essentially a power amplifier that puts out the electric power needed by an electric motor based on the torque and/or speed called for by the controller, which is a digital computer tasked with overall system control. As the industry has shifted in favor of variable-speed drives, the role of the drive has become more important.

Variable-speed motor/drive combinations use a synchronous ac motor with an encoder built in. The encoder signals the motor...Read More

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This question relates to comments I made in an article that appeared in the March issue of Control Engineering entitled, “The culinary art of mechatronics.” In that article, I described the (so far) four generations of programming language, which are roughly:
1GL — machine code (ones and zeros)
2GL — assembly code (such as microprocessor op codes)
3GL — human-readable programming languages (Fortran, C, C++)
4GL — frameworks (Eclipse, Microsoft Visual Studio, National Instruments ...Read More

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We are indebted to Bill McGovern, national sales manager for Dataforth Corporation for this detailed history.

The birth of battery technology is credited to the Italian physicist Luigi Galvani who, in 1780, discovered that a frog’s leg would “twitch” when brass hooks attached to the muscle were touched to an iron plate. He named this phenomenon “animal electricity”.

Later in 1800, the Italian physicist Alessandro Volta capitalized on Galvani’s frog experiment by inv...Read More

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Off the top of my head, I can think of 3 non-volatile random access memory (NVRAM) technologies in current use. I’m here defining NVRAM as a bitwise readable, writeable, and erasable memory technology for typical general purpose computers. In NVRAM devices, each bit has its own memory address, and can be part of the computer’s addressable memory along with the volatile static and dynamic RAM (SRAM and DRAM) chips shipped with the computer.

Electrically erasable programmable read only memory (EEPROM) is not NVRAM because it can only be read by a computer. It takes a special device, called a programmer, to erase or write to EEPROMs.

While computers can write directly to hard magnetic discs (also called Winchester drives or hard drives) ...Read More

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Flash memory cells individually resemble metal-oxide-semiconductor field effect transistors (MOSFETs) with an extra electrode. N-channel MOSFETs consist of two highly doped N-type silicon spots (source and drain) in a lightly doped P-type substrate connected to ground. Electrical connections are made to these spots, and a thin non-conducting dielectric layer covers all. A metal or other ...Read More

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A buck regulator, more properly called a buck convertor, is a dc-dc step-down power supply utilizing the fact that inductors react to electric-circuit fluctuations in such a way to keep the current flowing through them constant. This inductor property follows directly from Faraday’s Law: where I is the current flowing through the inductor, t is time, and E is an electromotive force generated by changes in the magnetic flux threading the inductor&r...Read More

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I’m revisiting this question because at least one reader was confused by my answer of March 24. If there’s one who commented, there must be many others who were also confused, but didn’t. So, I’ll try to clarify.

The full text of the question I was trying to answer is: “I have studied Microprocessor 8585A 8080 80 .. and all that designed since 199.. , please tell me about modern microprocessor and which are used in industrial applications nowadays.”

The bottom line is that you probably won’t use any of the conventional microprocessors designed for general-purpose computing. Either you’d be better off with a conventional packaged controller, such as a PLC, PAC, or need an embedded solution.

If you select either of the first two, you really have no choice of microprocessor &...Read More

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I’m not sure you’re asking the right question. What you really need for control applications is a controller, which is a complete computer system, not just the microprocessor. As a control engineer, that is what you want to concentrate on.

The figure below shows a simple single-axis control system. The brains of the outfit reside in the controller. All the other components are simple, low-complexity analog devices. While some of those external devices might contain some programmable elements, the system’s decision making engine is the processor running the controller. 
...Read More

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The full text of this question reads: What do we mean by say, 45 nanometer (45 nm) process in semiconductor fabrication? Does it refer to smallest component size or the wafer thickness? What are the difficulties and the limits in reducing the size?

It is neither. Semiconductor fabrication processes are classified according to a critical dimension (CD) rating. To understand what it means, we have to look at how semiconductors are fabricated, and it’s easier to start with the process as it existed about 20 years ago (please don’t hold me to the dates), then see how it has advanced.

Semiconductor devices (such as microprocessors, FPGAs, and other ICs) are fabricated by a photolithography process on disk-shaped silicon blanks called “wafers.” Semiconductor device fabrication facilities (called “fabs”) start with the...Read More

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The full text of this question is: I need to transmit voltage from fusebox to a receiver 5 m away. What kind of transmitter and receiver do I need?

Good news is that 5 m is actually not a very long way to carry a voltage signal, so you may not need any transmitter at all, and you probably already have the receiver. 

Bad news is that, depending on the signal you’re sending and the use you plan to put it to, you may have a difficult measurement problem, anyway. Let’s start with the best of all possible worlds, then see what we have to modify when things start to go bad.

The fact that you want to pull your voltage off a fuse box indicates that you may be living in an “order 100” alternating current (ac) world. Order 100 voltages (those between 30 and 300 V) are very easy to send 5 m (about 15 feet...Read More

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Let me start by admitting that simulating a whole robot is a lot more complex than the simple mechatronic systems I’ve done in the past. That’s a quantitative difference, however, rather than a qualitative one. The approach is the same. In this entry, I’ll only have room to outline the main steps.
The first thing to realize is that the robot does not exist by itself. It is closely coupled to its environment (It’s a Zen thing!), so you have to simulate the environment as well.

Another thing to realize is that, while the ultimate goal is motion in a three-dimensional environment, that’s not the “natural” dimensional space for the robot. A big part of the problem will be to translate back and fo...Read More

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