标签: electric

Robotics is hot these days, and it's certainly deserved. Today's robotic arms and systems are faster, cheaper, more precise, and lighter by large factors compared to those of even just a decade ago. The result is the deployment of these units in stationary and mobile applications that were impractical but are now very feasible. If you think this is just the usual post- CES type of public-relations hype, think again. Check out this article in a recent issue of Design News, "Mechatronics Solution Is Adept Enough to Produce a Bow-Tying Robot," which details a robotic system which ties decorative ribbon bows on boxes of chocolate. (The YouTube video here is both mesmerizing and hypnotizing, IMO.) The article is more than a puff piece on how smart the design team was; it explains some of the problems they encountered, the constraints they faced, the tradeoffs they juggled, how they used simulation tools to test out ideas in advance, and more. Also note that this is not a "science project" robot demonstration–though there is nothing wrong with that–this one is in daily commercial use on a production line.   This robotic arm and feed is able to consistently tie bows around boxes using loose, flexible ribbon, but be warned, the related video is hypnotizing in a strange, unintended way.   If you have ever worked with earlier robotic arms powered by hydraulics, you know how powerful and terrifying they can be, and at the same time, they can deliver lots of torque and power (different but closely related quantities). But they are nasty, with pumps, values, seals, leakage, and more. When things went bad, the result was often both a mess and dangerous, such as hydraulic fluid leaking, or worse, spraying out. Some fluid-powered systems eliminate the hazards of hydraulic fluid by using compressed air (pneumatics) in its place, but the air pressure has to be fairly high to get useful power, and high-pressure systems bring their own risks. Still, it's a very good alternative for low-load situations, such as the bow-tying one. Many of today's robotic systems have gone all-electronic, with fast, low-mass, precisely-controlled motors (BLDC or stepper). Even if hydraulics did not have the fluid pressure and leakage issues, they still have a major drawback compared to an electric-motor system: due to the inherent mass and compressibility of the fluid, there is an unavoidable time lag between changes directed to the servovalves and the end-effecters. These lags complicate the closed-loop control algorithms when you need fast, precise operation. While it is possible to add various compensation factors to the control algorithms to take this mass-based reality into account, this adds complexity and risk to the software along with additional errors. In contrast, with electric motors there is only a negligible lag of electronic switches and current flow that occurs between directing power to the motor and having it initiate motor action. This means the algorithms are dealing with a much crisper system, in control terms. Further, the lighter weight of the today's motors with their powerful magnetics compares favorably to hydraulic actuators, and this high power/weight ratio simplifies the remainder of the control design. By combining the best features of electric drives and pneumatic ones, a good system engineer can develop a system which meets previously unattainable objectives. Think about that fast-food production line; that's a likely application area. Coupled with improved algorithms for both sensored and sensorless control (such as vector field control, also called field-oriented control or FOC), the electric motor has become a powerful element – literally and figuratively – in the advances of high performance, easy to use, reliable robotics. Hydraulics still has many places where it is the best choice in terms of massive power delivery, torque, non-sparking, or other factors, of course. If you doubt that watch this 50-minute documentary " Sunken Ship Rescue " on the righting and salvage efforts of the cruise liner Costa Concordia . Still, for many small-to-moderate applications, electric is the way to go. What has been your experience with electric, pneumatic, and/or hydraulic robotic drives?

My chum Rick Curl went to see me in my office about a week ago. We had both decided that we desperately needed some face-to-face time to talk about the current Doctor Who (our feelings are mixed at the moment), and also to try to wrap our brains around the implications of the last episode of the current season, which aired a couple of weeks ago (I'm still reeling from the multi-layered surprises).   Speaking of surprises, Rick presented me with one of his old high-school science projects. (My understanding is that he's having a clear out -- getting this out of his house will make his wife happy, and I think Rick thought that having it in my office would guarantee that it would be lovingly displayed.)     This is a bit of a monster, being about three feet wide. It features an old telephone selector along with a bunch of relays. These relays are a mixed bag -- some switch really quickly to handle the pulses from a telephone dial (which used to be plugged into a connector, but which has become lost in the mists of time), while others have delays to handle the gaps between digits. The whole thing is something of a wonder -- especially for a junior at high school -- I'm not surprised to hear that Rick won first prize for this project.   During his clear out, Rick had also discovered a stack of around 1,000 brochures he'd had printed ages ago. These list the Ten Commandments of Electronics , along with Rick's company's name and contact details. Rick thought I might be interested in these, so he brought a few for me to play with.     These are really rather clever -- in addition to being humorous, they also offer some very useful advice, as follows: Beware thee of the lightning that lurketh in an undischarged capacitor lest it cause thee to be bounced on thy buttocks in a most ungainly manner. Cause thou the switch that supplies large quantities of juice to be opened and thusly tagged so thy days may be long and fruitful upon this earthly vale of tears. Prove unto thyself that all circuits that radiateth and upon which thou worketh are grounded lest they lift thee to high-frequency potential and cause thee to radiateth also. Take care that thou useth the proper method when thou taketh the measure of high-voltage circuits in order that thou doth not incinerate both thee and thy meter; for verily, though thou hath no account number and canst be easily replaced, thy meter doth have such a number and -- as a consequence -- its loss will bringeth much woe unto the supply department. Tarry thou not amongst those who engage in intentional electric shocks, for they are surely nonbelievers and are not long for this world. Take care that thou tampereth not with interlocks and other safety devices, for this will incur the wrath of thy seniors and bringeth the fury of the safety officer down upon thy head and shoulders. Worketh thou not on energized equipment, for -- if thou doeth -- thy buddies will surely be purchasing beers for thy widow and consoling her in ways not generally acceptable to thee. Verily I say unto thee, never service high-voltage equipment alone, for electric cooking is a slothful process and thou might sizzle in thine own fat for hours before thy Maker sees fit to drag thee unto His fold. Trifle thou not with radioactive tubes and substances lest thou commence to glow in the dark like a lightning bug and thy wife be frustrated nightly and have no further use for thee (excepting thy wage). Commitest to thine memory the words of the prophets, which are written in the instruction manuals, which giveth the straight dope, and which guideth thee such that thou will not maketh any mistakes.   The funny thing is that Rick says he no longer remembers where he discovered these commandments or who wrote them in the first place, but when he recently performed a search on the Internet, he discovered that several people had attributed them to him.   Now, looking at the above commandments, are there any additional ones you think we should have? If so, please post them as comments below.

My chum Rick Curl dropped into my office several days ago. We had both decided that we desperately needed some face-to-face time to talk about the current Doctor Who (our feelings are mixed at the moment), and also to try to wrap our brains around the implications of the last episode of the current season, which aired a couple of weeks ago (I'm still reeling from the multi-layered surprises).   Speaking of surprises, Rick presented me with one of his old high-school science projects. (My understanding is that he's having a clear out -- getting this out of his house will make his wife happy, and I think Rick thought that having it in my office would guarantee that it would be lovingly displayed.)     This is a bit of a monster, being about three feet wide. It features an old telephone selector along with a bunch of relays. These relays are a mixed bag -- some switch really quickly to handle the pulses from a telephone dial (which used to be plugged into a connector, but which has become lost in the mists of time), while others have delays to handle the gaps between digits. The whole thing is something of a wonder -- especially for a junior at high school -- I'm not surprised to hear that Rick won first prize for this project.   During his clear out, Rick had also discovered a stack of around 1,000 brochures he'd had printed ages ago. These list the Ten Commandments of Electronics , along with Rick's company's name and contact details. Rick thought I might be interested in these, so he brought a few for me to play with.     These are really rather clever -- in addition to being humorous, they also offer some very useful advice, as follows: Beware thee of the lightning that lurketh in an undischarged capacitor lest it cause thee to be bounced on thy buttocks in a most ungainly manner. Cause thou the switch that supplies large quantities of juice to be opened and thusly tagged so thy days may be long and fruitful upon this earthly vale of tears. Prove unto thyself that all circuits that radiateth and upon which thou worketh are grounded lest they lift thee to high-frequency potential and cause thee to radiateth also. Take care that thou useth the proper method when thou taketh the measure of high-voltage circuits in order that thou doth not incinerate both thee and thy meter; for verily, though thou hath no account number and canst be easily replaced, thy meter doth have such a number and -- as a consequence -- its loss will bringeth much woe unto the supply department. Tarry thou not amongst those who engage in intentional electric shocks, for they are surely nonbelievers and are not long for this world. Take care that thou tampereth not with interlocks and other safety devices, for this will incur the wrath of thy seniors and bringeth the fury of the safety officer down upon thy head and shoulders. Worketh thou not on energized equipment, for -- if thou doeth -- thy buddies will surely be purchasing beers for thy widow and consoling her in ways not generally acceptable to thee. Verily I say unto thee, never service high-voltage equipment alone, for electric cooking is a slothful process and thou might sizzle in thine own fat for hours before thy Maker sees fit to drag thee unto His fold. Trifle thou not with radioactive tubes and substances lest thou commence to glow in the dark like a lightning bug and thy wife be frustrated nightly and have no further use for thee (excepting thy wage). Commitest to thine memory the words of the prophets, which are written in the instruction manuals, which giveth the straight dope, and which guideth thee such that thou will not maketh any mistakes.   The funny thing is that Rick says he no longer remembers where he discovered these commandments or who wrote them in the first place, but when he recently performed a search on the Internet, he discovered that several people had attributed them to him.   Now, looking at the above commandments, are there any additional ones you think we should have? If so, please post them as comments below.

Teeth may soon be repaired without the drill, so dreaded by some, as a new technique has been developed at King’s College London.   It is called electrically accelerated and enhanced re-mineralization (EAER), and the inventors claim that it accelerates the natural movement of calcium and phosphate minerals into the damaged tooth. The technique employs a two-step process. First, the damaged area of enamel in the tooth is prepared, and then tiny electric current pulses are used to move the minerals needed for repair into the repair site. It is currently in development, and its developers suggest it could be available for general use in about three years.   To those of us with an interest in non-volatile (NV) memory, the process strikes a chord. The movement of material by electro-migration is a bane to developers of some types of emerging non-volatile memory, and the very driving force for others.   The building of links, usually conducting, by electro-migration-driven movement, by electro-chemical means (e.g., plating), by electro-crystallization, or by electric field, in a manner that can be reversed, are now all part of the emerging NV memory mix. Those same effects can also appear as reliability problems by shortening the life of some types of memory device as well as other solid-state devices.   The similarity between this new emerging dentistry and NV memory technology is illustrated in the two cross sections shown in the figure below. On the right-side is a cross section of a generic NV memory with the active material between two electrodes (green). The conducting link required to write the memory to one of its logic states grows from one electrode towards the other.   On the left side of the figure is the cross-section of a tooth undergoing repair with the electric pulses. The repaired tooth material is growing into the active material. The active material (shown in pink in the tooth cross-section) is what must be applied as part of the preparation process described as the first step. This will also need to have a sort of electrode in contact with it in order to apply the electric pulses. Unlike most non-volatile memory, the material deposited as the repair does not have to be conducting. But the pink preparation material will need to be (unless the process of moving the material is electric field driven, in which case it could be dielectric and more insulating). In the figure, we have assumed that a ground link to complete the circuit is through the body and gum.   Clearly, the dentists and their patients do not require the growth to be reversed, so perhaps in an electronics industry analogy, this process should be more accurately classified as one-time programmable memory (PROM). In any case, it is certainly an interesting development.   A new company named Reminova , based in Perth, Scotland, has been set up to commercialize the research and is in the process of seeking private investment to develop the EAER technology. It is the first company to emerge from the King's College London Dental Innovation and Translation Centre, which was set up to take novel technologies and turn them into new products and practices.   Ron Neale is an independent electrical/electronic manufacturing professional .

Here's another post, in which we pause for a moment to take a deep breath (hold it... hold it... now exhale), slow down, relax, and start winding down in preparation for the weekend. As part of this exercise, I've gathered a few choice diversions for your delectation, delight, pondering, and rumination. This week's humble offerings are as follows: No. 1: Do you think you are having a bad day? Is it as bad as sending eye-watering amounts of electricity surging through your tongue? Sometimes, no matter how horrifying a video is, you just cannot look away. ( Click here to discover more.) No. 2: Unfortunately, Mehdi Sadaghdar—the star of the previous video—just doesn't know when to stop. His videos on how to change an electric light bulb ( click here ) and how to build an electric guitar ( click here ) cannot fail to make you cringe and wince with empathetic pain. No. 3: I don't know about you, but my eyes are still watering from the previous videos. Let's change pace and look at something that makes one gasp in wonder—a 240-year-old clockwork automaton that can write. ( Click here to discover more.) No. 4: Now I feel in the mood for the video equivalent of comfort food. One of my all-time favourite videos is the trick the Improv Everywhere group played in Grand Central Station. Even if you've seen this before, it's always worth another look. ( Click here to discover more.) No. 5: Speaking of improv, another of my all-time favourite videos is the one where over 200 dancers perform "Do, Re, Mi," from The Sound of Music in a Belgian train station. Once again, even if you've already seen this, you need to watch it again, because it's simply impossible to view this all the way through without ending up with a great big beaming smile on your face. ( Click here to discover more.) As usual, if you know of any interesting sites you'd care to share, please comment below.