For hybrid/electric vehicle battery management systems.
Design News Staff -- Design News, February 25, 2011
Linear Technology's LTC 6803 is a second generation high voltage battery monitor for hybrid/electric vehicle (HEVs), electric vehicles (EVs) and other high voltage, high performance battery systems. The LTC6803 is a complete battery measuring IC that includes a 12-bit ADC, a precision voltage reference, a high voltage input multiplexer and a serial interface. Each LTC6803 can measure up to 12 individual battery cells in series. The device's proprietary design enables multiple LTC6803s to be stacked in series without optocouplers or isolators, permitting precision voltage monitoring of every cell in long strings of series-connected batteries. The LTC6803 follows the LTC6802 with the same functionality and pinout, plus a number of significant performance enhancements.
The maximum total measurement error of the LTC6803 is guaranteed to be less than 0.25 percent from -40 to 125C. The LTC6803 offers an extended cell measurement range from -300mV to 5V, enabling the LTC6803 to monitor a wide range of battery chemistries, as well as supercapacitors. Each cell is monitored for undervoltage and overvoltage conditions, and an associated MOSFET is available to discharge overcharged cells. Added functionality is provided by an onboard 5V regulator, temperature sensor, GPIO lines and thermistor inputs.
For long-term battery pack storage, the current consumed by the integrated BMS can potentially unbalance the cells. The LTC6803 addresses this concern with a standby mode that draws less than 12uA. The power input of the LTC6803 is isolated from the stack, allowing the LTC6803 to draw current from an independent source. When powering from this input, the current draw on the pack is reduced to less than 1µA.
New breed of sensors incorporates 32-bit processor on board.
Charles J. Murray, Senior Technical Editor, Electronics &Test -- Design News, February 24, 2011
Electronic products ranging from mobile phones to fitness monitors may soon be smarter than ever. Thanks to sensors with onboard intelligence, those products will be able to "think" as never before, gathering data and then using it to reach conclusions - not just about the information gleaned from a single sensor - but about the world around them.
Onboard intelligence will help sensors integrate tilt, heading and orientation information. Source: Freescale Semiconductor
Click here for larger image.
For the electronics industry, the new breed of sensors represents a small revolution of sorts. Freescale Semiconductor, a component supplier that's just now bringing the technology to market, says that the micro-machined smart sensors could enable everyday products - such as automotive airbags or iPhones - to put their knowledge into context.
"More and more, it's not just about taking in the data from a single element, but about understanding everything around you," says Wayne Chavez, operations manager for consumer and industrial sensors at Freescale. "Whether it's altimetry, directional heading, or just the pace that you're walking, all these things are measurable. And all of them can be put into the context of your surroundings."
This "contextual" sensing represents a stark departure from the embedded computing that's gone on up to now. The reason: Most of today's sensors are dumb; they take an analog pressure or temperature reading and send it off to a microcontroller, which does the thinking.
Freescale believes there are profound advantages to be realized by changing that scenario. That's why the company has invested in the development of a two-level sensor - a MEMS sensor chip, such as an accelerometer, stacked atop an ASIC (application specific integrated circuit) incorporating a microcontroller. In this embodiment, the CMOS-based ASIC chip houses the brains, as well as an interface to an I2C communications databus. During operation, it takes the analog signal from the sensor chip above it, then using information that's available from the databus, begins to put the information into a larger context.
The advantages are not only that the "thinking" takes place on board the sensor, but that the sensor offloads computing chores from the main CPU and saves power in the bargain. The configuration is especially enticing to designers of smart phones, who now must integrate readings from GPS systems, pressure sensors, accelerometers and a half-dozen other sources.
"Today, all of this data comes into the phone and the question becomes, how do you manage it all?" Chavez asks. "You could manage it with your applications processor and be interrupted every time you receive a pressure sensor reading, magnetometer reading or gyroscope reading. Or you could put the intelligence on the sensor."
Contextual sensing could help vehicles to selectively fire driver, passenger and curtain airbags. Source: Freescale Semiconductor
New Frontier of Applications
Freescale engineers cite the automotive airbag as a product that could benefit from contextual intelligence. Airbags, which do an exceptional job of being available when called upon, are nevertheless known to have rare inadvertent deployments - or worse, no deployment when needed. Most such situations occur when the integrity of a sensor signal is breeched, causing the controller to inappropriately disable or enable a bag.
But Freescale believes it can reduce or eliminate those situations by building self-diagnostics into the sensor. "We're reaching the point where we can check ourselves, more often and in real time, to better understand the integrity of a measurement," says Jim Grothe, marketing manager for Freescale's MEMS Automotive Business. With smart sensors, Grothe says, airbag modules would be unlikely to make wrong decisions based on a single-point, faulty sensor measurement.
Moreover, smart sensors could enable airbag systems to be more selective. By communicating with one another and understanding the nature of a particular crash, the airbag system might be more able to turn on and off the appropriate bags, thereby saving on replacement costs. "If you have a front-end crash, you might only want the front airbag to deploy," Grothe says. "If you have a rollover and there's no frontal impact, maybe you don't want that front bag to deploy."
Nowhere, however, are the advantages of smart sensors more evident than in the new breed of mobile phones. There, the proliferation of applications is growing so fast that many engineers are hard-pressed to keep up with them. Many phones now incorporate accelerometers for gesture recognition, magnetometers for heading information, GPS for location, gyroscopes for game play and even pressure sensors that serve as barometers, helping users transform their phones into mini-weather stations.
Smart sensors become especially important in such products because the applications are often interdependent. To accurately measure a magnetic field vector, for example, the phone must know its own orientation - that is, if the user is tilting it up or down, or holding it sideways.
"The three-axis accelerometer becomes critical for making other measurements," Chavez says. "No matter how you hold your handheld device, you have an orientation based on gravity, and that has to be used to auto-correct the measurement that describes your heading."
Freescale’s MMA9550L MEMS sensor includes a 32-bit processor and databus connectivity. Soon the company hopes to add a gyroscope, pressure sensor, touch sensor and magnetometer in a single sensor package. Source: Freescale Semiconductor
Click here for larger image.
Freescale says it's ready for such complex applications. In June, the company rolled out a MEMS-based accelerometer called the MMA9550L, which incorporates a ColdFire 32-bit processor, along with databus connectivity and power management in a 3 x 3 x 1 mm package. More recently, it has introduced a magnetometer-based sensor, along with software solutions for gesture recognition systems and pedometers, to its Xtrinsic line of sensors. Ultimately, the company's engineers say they will pack a gyroscope, pressure sensor, touch sensor and magnetic sensor in a 5 x 5 x 1 mm package, along with the accelerometer and processor.
The company's engineers believe the idea of a sensor with onboard intelligence will grow and creep into new applications, including monitors for fitness, home heath and onboard tire pressure, as well as e-book readers and tablet computers.
"There are still going to be some applications that will still use traditional sensors," Chavez says. "But for these sensors, the frontier is wide open to discovery."
Analytical, numerical and experimental methods applied to the characterization of mechanical components, structures, systems and materials. These activities intimately support product development, safety, weight minimization and component optimization for aerospace, automotive, electronics and general manufacturing. Current areas of emphasis include stress, strain and deformation analysis; modeling, testing and verification of kinematics and dynamic systems; applied finite elements; plate, shell, and pressure vessel characterization; composites; micromechanical design and analysis; photomechanics and optical techniques, and multi body problems. Professors Engelstad,Lovell, Rowlands, Uicker.
The Polymer Engineering Center focuses on advancing technologies for a wide range of polymer and polymeric composite manufacturing processes. Professors Ferrier, Giacomin, Li, Osswald, Rowlands, Shkel, Turng.
Development of fundamental and applied engineering knowledge related to biomechanical systems, and the application of engineering expertise towards the design and development of leading-edge rehabilitative, assistive, and adaptive technologies that allow those with disabilities to achieve greater independence. Professors Beebe, Chesler, Ferrier, Fronczak, Gruben, Martin, Ploeg, Thelen.
The primary thrust of Computer-Aided Engineering research is to develop mathematically sound theories, computationally efficient algorithms, and next generation tools for modeling, design, and simulation of a wide range of engineering artifacts and processes. Focus areas include mechanical, micro/nano-mechanical, electro-mechanical, thermal, fluid, and other multi-disciplinary and multi-scale systems. Professors Engelstad, Shapiro, Suresh, Turng, Uicker.
Whenever purchasing a car, you would almost always hear of stuffs like “2.0 liter V-6”, “four-stroke inline”, “fuel injection” etc. These all points to your car’s engine and this article will give you a basic knowledge of how your car’s engine works.
Basic Definition of Car Engines
Car engines are internal combustion engines and they work by converting gasoline into mechanical energy (motion). In order to create mechanical energy, car engines needs to combust (explode) gasoline in a closed chamber to push of a mechanical part (piston) down and up. The up and down motion of the piston creates a circular motion in the crankshaft via the connecting rods. This is more clearly seen in the animated picture above.
Car engines are actually simple but ingenious in design. Almost all car engines today are four-stroke engines. This means that there are four stages on how an engine transforms gasoline into mechanical energy. These stages are the intake, compression, combustion and exhaust. Each stroke (stage) is a representation of the upward or downward movement of the pistons inside the chamber of the engine. We all know that gasoline lights up when ignited. Now in order for gasoline to combust (explode), it needs to be mixed with oxygen (air) then compressed before being ignited. The by-product or the exhaust then needs to be released. These all happens in the four strokes (stages) of your engine.
Four Strokes of an Engine
Intake Stroke – This is where the position of the piston inside the chamber is lowest. As the piston moves down to it’s lowest point, gasoline and oxygen (air) is introduced inside the chamber. Most of today’s car engines introduce gasoline through a needle like system called fuel injection. This enables for a more controlled and accurate mixture of fuel and air inside the chamber and increases the efficiency (miles per gallon) of your car. Compression Stroke – After the fuel-air mixture is introduced inside the chamber, the piston now moves upwards (by the force of the combustion). This compresses the mixture of fuel and air inside the chamber to a point where it can be combusted. Combustion Stroke – As the piston reaches the topmost part of the chamber (also known as the Top Dead Center or TDC) spark kicks in to ignite the compressed air-fuel mixture. The spark is generated by the spark plug in gasoline engines or by the glow plug in diesel engines. The force of the combustion pushes the pistons downwards and is converted into a circular motion by the connection of the connection rods to the crankshaft. The circular motion of the crankshaft is the actual mechanical part, which makes the wheels (and other mechanical systems) turn. Exhaust Stroke – After the air-fuel mixture combust and the pistons pushed downward, the chamber is now filled with exhaust (the by-product of the air-fuel combustion). As the piston again reaches it’s lowest point, the energy of the combustion of air-fuel mixture is still in the piston and the only way for it to move is upward. At this point, a second valve is opened to let the exhaust escape the chamber as the piston moves upward.
The liters and the V’s
The liters that you always see or hear when buying are actually the amount of space in all piston chambers of your car’s engine. A bigger chamber of course would mean more air-fuel mixture could be combusted. More air-fuel combustion means bigger explosion and bigger explosion means more power.
The letter V that you see, which is usually beside the number of liters, refers to the type of engine. There are three types of engines used today; these are the inline, V’s and flat. To distinguish these types of engines, refer to the pictures below.
In 1950, the magazine Model Airplane News published a two part article describing a simple 0.06 cuin engine for home construction called the Little Dragon. The designer and author was Roy Clough Jr. Roy appears to have been the man called on when something out of the ordinary was required; engines, free-flight helicopters and ducted-fan designs, Roy did them all. His concept for the project was that is should be:
"..a project any amateur machinist can tackle with full confidence of good results. It does not require any special tools, special talents, or extreme precision. A large part of the total time spent in developing the design was devoted to eliminating awkward machining jobs, delicate operations, and tricky assemblies. If the reader owns a small lathe and can center a piece of stock with 1/64", he need have no qualms about being able to turn out the job."
Roy's design was the basis for a number of derivative designs. Taking the Little Dragon as his starting point, Tom Crompton developed a series of simple glow and diesel engines which he called the EZE. The appeared in the English magazine Model Engine World. Further detail on these is available on the EZE Construction Pages of this web site.
Having been asked to develop a simple engine for home construction on minimal equipment for Model Engine Builder magazine, I began examining the features other designers had adopted in this same quest. Naturally, the LD was one of the engines considered. Knowing that readers of the Model Engine News Web Magazine would find descriptions of the types examined of interest, my thoughts were collected and placed on a page titled Design for Beginners page.
Although I had no pre-existing bias against the design, as I began to look closely at it, I found a number of aspects that I questioned in a beginners' engine design (click here to read what I objected to). Having published this, I found my criticisms of the design were weighing heavily on my mind, although I did not retract from them. There was obviously only one answer: build an example of the engine as close as possible to the published plans and see if the things I envisioned as problems were real of imagined. The pages referenced show the machining of all components in considerable detail. They were built from my own CAD plans drawn to the original design. Registered Members of Model Engine News (ie, those who have bought the MEN Only CD) may download these plans from the Members Only Area.
The pace and complexity of modern industrialized life preconditions us to believe in the need for expensive speciality and sub-speciality services for taskes that can be accomplished at home, with a little perseverence (although not on a commercially viable basis). As an example, take the restoration of old model IC engines. Many of these share a common problem; they have (or had) red anodized, screw on cooling fins to which a past owner(s) has taken a large set of multy-grips and a cold chisel, resulting in horrendous graunch marks. A good restoration would require the heads be cleaned up and re-anodized. After some experiments, my co-researcher and I achieved some remarkably successful results in color anodizing using the most primitive of equipment. So if you're curious, here's how. For collectors , the engines in question were two Australian Taipan 1.5cc (a round head and a flat top head), a Frog "Vibramatic" and two ME Herons.
0. Research! - in this case, magazine articles from SIC (Strictly Internal Combustion) and MEW (no, not Model Engineer's Workshop, the other British one, Model Engine World), plus the Tee Workshop Practice book). Naturally, all were somewhat contradictory and follow-up letters to the editor in MEW added more confusion. My description below (cut from an email to the "Motor Boys" fraternity) gives the process which is now working consistantly for me.
1. De-anodize the old part by imersing it in a weak caustic soda solution - like a level tea spoon disolved in an old coffee cup of warm water. Takes no more than 5 minutes and the part may turn "black" depending on the alloy. Keep this up until all, or virtually all the old color has disappeared and the outer surface is dull. Rinse under tap water and scrub with an old tooth brush to remove surface scale. Rubber gloves are probably a good idea for this (and other) process.
2. Mount on some kind of mandrel and skim it up with minimal metal removal on the outside (would you believe the Taipan head internal thread is 27 tpi? Some kind of pipe thread, I think. With only a QC box on the Myford, I cut a loose 28 tpi and that worked well enough). Finally, run at high speed with fine wet 'n dry using kerosene. I also buffed them on a Scotch-Brite belt that runs on one side of my bench grinder.
3. Bend a strip of aluminum to go inside the head/whatever, making good spring contact. This needs to be able to pass the anodizing current, so take a little care. The other end of the strip will be screw mounted to a common hanger bar connected to the positive side of the current source - hence it is the "anode" and we have the origin of the term anodizing. Aluminum welding rod is another hanger candidate, although I've not tried it.
Now back into a fresh caustic solution for about 30 seconds to de-grease, then rinse in cold, demineralized water. From the time it comes out of the caustic, avoid all direct contact with the part. The oils on your fingers will leave patterns on the part, as will the minerals present in some domestic water supplies.
4. The anodizing bath is 1:1 battery acid and demineralized water (my cloths dryer condenses water into a collector for me, so I've a never ending supply of this). The container should be clean and plastic. I used a 2 litre square food container with a snap-on lid for storage. I've no indication of how long a batch of electrolyte like this will last. So far, mine has been used ten times with no apparent change in the results, but anyway, we are not talking significant cost here - just be carefull disposing of it.
The cathode used is a piece of lead sheet hammered flat from an old length of lead covered communications cable. It's bent in a U shape inside the bath, with another U bent so it sits on one rim of the container. The negative wire from the current source gets attached to it (soldered). The refs say it should surround the part (hence the U shape) and be at least of the same area. I went for massive over-kill in the cathode area and this has worked.
The aluminum hangers of part(s) to be anodized are then screwed to a bar (I used 1/8" al strip, but any thing would do) that sits over the top of the bath and carries the positive wire from the current source. Plastic cloths pegs either side of the bar prevent it accidentally touching the cathode. That would be bad.
The refs say about 65-70 degrees F for the bath. That's about room temp for water here in spring, so I didn't bother to heat in any way.
5. Now the techie-part. The anodizing current required is about 100 mA per square inch (all sources disagree, so this is a good, round number average). This apparently impacts the pore size formed and hence the ability of the oxide to accept and trap the color. You can laborously calculate the surface area, or aproximate it. From the heads I've done, a rule of thumb seems to be surface area = 2.5 times the area of the head calculated as a simple cylinder. I didn't bother to include the area of the hangers, but if they are big and flat, it would be a good idea to figure them in.
The current source needs to be DC and about 12 to 20 volts, capable of delivering at least 2 amps and variable in some way. You also need to be able to measure this. My flying buddy (who is the head engineer at a local radio station) "found" a supply that was close to this, but not variable, so we fitted an auto-transformer (Viaiac) but a drill speed control to the mains side of it would also do the job. A battery charger driven by a speed controller would probably work ok. My current source has some filter capacitors on it which a battery charger wouldn't though.
After you have the aprox surface area for each part in the batch, add them up and divide by 10 to get the current (in amps) required. Hook up the source negative to the lead cathode; the positive to the black lead of your multimeter (which should be set to the 5 or 10 amp DC current range) and the meter red lead to the wire coming off the hanger with the parts to be anodized. Now plonk 'em in the bath and crank it up to about the reading calculated (err on the high side). Start the stop watch and observe the part. After a minute or so, a fine stream of bubbles should start to form.
Keep this up for 45 minutes to an hour, periodically checking the current and adjusting as required. At any time you can lift the bits out (turn off the current and hold via the bar). If they appear a dull gray, that's good. If not, run them a while longer. This is a real suck it and see operation. Avoid breathing when inspecting the bath - it's evil stuff (explosive, too). I did this out doors - I suspect the fumes would have attacked every piece of steel in the workshop.
When satisfied, rinse parts in demineralized water and place them out to air-dry throughly. This is important! I put them in the sun for an hour or so, but avoid all direct contact (oils in the skin etc). We are going to depend on capillary action to get the die into the microscopic pores formed by the anodizing, so the dryer the better. Even over-night would probably be ok. Believe me, going into the color bath wet gave no color take-up at all, even though one source advocated this!
6. The color bath is not a precise process. I had success with a product called "Dylon" used for dying fabrics that I obtained from the drug store (chemist shop). It comes in little round plastic tubs with a crimped on alloy cap and seems to be globally available. The color "Scarlet" works great - but their "Emerald" was a dismal failure, so I conclude that the dye particle size varies with the color. It it's too large, it won't go into the pores. I disolved half a tab of die in a 1 pint jar of de-mineralized water to give a very concentrated mix. This is warmed in the micro wave oven for 1 minute before use (this step may not be necessary, but having a process that works, I don't want to vary it!).
Put the kettle on and start it heating to make steam, then pop the part in the dye (holding it only by the hanger) and dunk and swish it around. Try to avoid hitting the sides of the jar. At one stage, I bubbled compressed air into the jar, but swishing seems to work just as well. Take the part out periodically an look at the color absorbtion. When it seems like it's got all it's going to get, give it a bit more and make sure you've got steam. This will take only a few minutes.
7. Tap off the excess liquid, then place part in the steam comming from the kettle. Rotate, twist, turn, etc to get steam into all knooks and crannies. This is closing the pores, sealing in the color (and apparently changing the type of oxide formed from a hydride to a hydrate - at least I think that's what one of the refs said). After you've burnt yourself a couple of times and are totally sick of it, take part and kettle to the sink and pour the boiling water all over the part.
8. You can touch it now. Dry it off - I used paper towels - and expect a little color to rub off, but if you've got it right, not a lot. Finally rub some machine oil over it. This brings out the luster and changes it from merely nice to absolutely spectacular.
Thats it! As I said - the die particle size is the critical thing. My friend Peter Crewdson, from Canberra was staying with at the time (I'm RC, he's PC and *still* an aviation electronics tech with our FAA equivalent). He and I experimented with red and blue ink as the die as well as red and green Dylon. Only the "scarlet" Dylon worked acceptably, but it worked great. He's gone home determined to anodize the entire Canberra airport red, just for the fun of it.
If it fails, go back to step one and try again. Our test piece (a reject Schroeder Deezil head with a strange internal thread cut for no valid reason) went round this loop three times. The final anodizing is good, but the surface is dull due to fine pitting, probably from the multiple caustic dippings to de-anodize - so good idea to practice until you're confident and if you must de-anodize, re-polish each time.
I've got some blue Dylon to try, and the owner of the Frog, Herons and one of the Taipans who donated the power supply has just dropped an old Taifun on me with a tab of pink Dylon - he insists it had a pink head - but you'd never know to look at the sad old thing. That will probably be the next experiment, along with the stuff-up head for the Owen "Mate" (was busily turning out the id to match the od of the fin groove - got to within 10 thou of creating a set of rings before I realized what was happening!) which I'll try the blue on.
This is a real imperical process, but after we arrived at it, we did three totally successful batches in a row, over two days, so I think we have it down (for the setup we used, anyway). The more pure the alloy, the better the color absorbtion. We hung one batch on aircraft alclad hangers. The 99.9% pure coating came out an absolutely brilliant red, but on the edge you could see that the core (high manganese and silicon, I think) was much darker and duller.
Update 11/18/1998:
I've been contacted by the author of the MEW article (Mr N Rat) who tells me he has recently restored a blue head AM 15 using Dylon "Kingfisher" blue with spectacular results. This seems to confirm my theory that the particle size in Dylon brand varies with the color as my blue experience was not so good.
I've also tried varying the current/time ratio to see how this effects pore size and hence, color absorbtion. I think I can definitely say using a higher current (up to 130 mA per square inch) gives much better results than lower (less than 100 mA). This conclusion was derived from results observed in red anodizing three batches, so they're not exactly conclusive, but good enough that I'm now going to use higher current for a shorter duration as standard practice.
Preface: Multimedia refers to an electronically delivered combination of media including video, still images, audio, text in such a way that can be accessed interactively.
History: The term "multimedia" was coined by Bob Goldstein in 1966.
Multimedia Category:
·Linear ( cinema presentation )
·Non-Linear ( User interactivity-Computer Games )
Major characteristics of Multimedia:
·Computer controlled, Integrated Systems,Digital representation of Information.
