Help with engine monitoring project ??
Shawn Mack
Posts: 7
Hello,
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My name is Shawn and I'm new to this forum. I've only used a stamp one time a few years ago for a project·I had. I have a new project I’m working on and would be willing to pay someone for their help. I want to monitor a turbine engine. It’s rather simple, believe it or not. Here's a quick rundown of what I'm trying to do and you can tell me if it's possible.
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I have a turbine engine that I want to control. The functions are very simple. I have it running now with an "off the shelf" engine governor. I would like to monitor EGT (exhaust gas temp) using the parallax DS2760 and a "k" thermocouple which·I have, oil pressure with the current sending unit, real simple, at 6 PSI it closes a circuit to turn off the oil pressure light, when it drops below 6 PSI the light comes back on. Also read RPM with the existing magnetic pickup that's mounted on the gear case that reads pulses from the main gear. It pulses 20 times per revolution and max rpm is a little over 6000 rpm or 2042Hz. And I need an over speed circuit so if the rpm happens to go 10% above the 2042Hz it will shut power off to a fuel solenoid and shut the engine down. Last but not least, I need to control a servo or stepper motor that control the fuel lever for the throttle. At start up it runs up to 50% power (3000 rpm) then by turning a pot it will throttle the engine up, VERY SLOWLY, to 100% (6000 rpm). It stays there; this engine is designed to run at 100% all the time. And I would like a LCD display to show me %rpm. I have anywhere between 12 and 24 VDC for power as it requires 24 for the starter and 2 of the fuel solenoids. The thought seems simple but you tell me if this is possible.
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I have the old INEX-1000 experimenter's board to work with, not sure if I can or not. Let me know.
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Thank you for your time,
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Shawn Mack
Orlando, FL
407-808-6225
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·
My name is Shawn and I'm new to this forum. I've only used a stamp one time a few years ago for a project·I had. I have a new project I’m working on and would be willing to pay someone for their help. I want to monitor a turbine engine. It’s rather simple, believe it or not. Here's a quick rundown of what I'm trying to do and you can tell me if it's possible.
·
I have a turbine engine that I want to control. The functions are very simple. I have it running now with an "off the shelf" engine governor. I would like to monitor EGT (exhaust gas temp) using the parallax DS2760 and a "k" thermocouple which·I have, oil pressure with the current sending unit, real simple, at 6 PSI it closes a circuit to turn off the oil pressure light, when it drops below 6 PSI the light comes back on. Also read RPM with the existing magnetic pickup that's mounted on the gear case that reads pulses from the main gear. It pulses 20 times per revolution and max rpm is a little over 6000 rpm or 2042Hz. And I need an over speed circuit so if the rpm happens to go 10% above the 2042Hz it will shut power off to a fuel solenoid and shut the engine down. Last but not least, I need to control a servo or stepper motor that control the fuel lever for the throttle. At start up it runs up to 50% power (3000 rpm) then by turning a pot it will throttle the engine up, VERY SLOWLY, to 100% (6000 rpm). It stays there; this engine is designed to run at 100% all the time. And I would like a LCD display to show me %rpm. I have anywhere between 12 and 24 VDC for power as it requires 24 for the starter and 2 of the fuel solenoids. The thought seems simple but you tell me if this is possible.
·
I have the old INEX-1000 experimenter's board to work with, not sure if I can or not. Let me know.
·
Thank you for your time,
·
Shawn Mack
Orlando, FL
407-808-6225
·
Comments
·· One thing I just noticed is that you mentioed the DS2760, which is a 1-Wire device.· You need a BS2p or higher to talk to a 1-Wire device like that.· Also, your RPM readings would be paced, because in between COUNTing the RPMs, the BASIC Stamp would have to read the temperature from the thermocouple, which is on the order of milliseconds, but the higher the temperature the longer the read time due to LOOKUP tables.· Not that it can't be done.· I would tackle one thing at a time...I know (even recently) there have been some threads on here regarding engine RPM monitoring.· Maybe someone who was involved can post a link to one of those threads for you.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I can or would use any stamp that would do all this at one time. I'm researching the stamps now to see which one may work best. The last time I used one I only needed a BS2. The EGT ranges between 600F to 1180F which is the normal operating range. I read a few posts about rpm monitoring and just thought I'd ask in the main forum. I think I emailed a few members personally. The turbine is in a generator, military issue. At start up it spools up to 50% then is controlled manually to 100% and stays there. The start up procedure is all manual but it would be cool to automate that as well. Here's how it starts, master on, depress starter button, as it spools up, at 4% I turn on the start fuel solenoid and turn on the turbine exciter (spark plug) both via a SPST switch with 24VDC, the engine then quickly spools up to around 40%, then I turn on the main fuel, SPST switch with 24VDC to main fuel solenoid, and it then spools up to the minimum fuel setting, 50%. Then I want to be able to adjust a pot that controls a servo/step motor to move the fuel lever to 100%. It runs off Jet-A fuel and is pretty awesome, not to mention loud. It's just the controls now are all manual and old. There has to be a simpler way so I figured a stamp would do it.
Thanks for the response,
Shawn
In the WAM book their is an example on how to control a servo with a Pot through a basic stamp here is the link to the book so you can download it.
http://www.parallax.com/dl/docs/books/edu/Wamv2_2.pdf
Look at page 153 in the .pdf
What this all boils down to is multi-point, multi-proccesor
As far as real-time monitoring goes, there are ways around the RCTIME comand (and the related wait time for a reading)
some of the ways:
(1) One ADC converter per sensor, DATA can be on a one wire data bus (for serial ADC's) and multi flow control pins and code to control and filter the multiple readings from thie multiple ADC's
or
(2) With the aid of an analog MUX IC you could put that on the input side of a single ADC use code to select the input of the MUX and then quickly take a sample from the ADC and send it to the stamp in serial format where you could rapidly "decipher" the serial data and display it on anything you like via SEROUT.
or
(3) Use a separate stamp (like a BS1) to collect/proccess sensor data and have updated data waiting for a SEROUT comand from a central stamp (like a BS2 or better) to collect each stamps data for display/control.
or
(4)Purcahse a propeller (http://www.parallax.com/propeller) like i'm about to instead of all of the above. With 8 "COG's"(something like a BS2) and a central HUB running at 20MIPS and fast enough to run Baseband/Broadcast video and VGA
Monitor all your sensors, proccess the DATA, control GUI's, digital crossovers,servos/relays/stepper motors, and display stuff SIMOTANEOUSLY!!!
The pulse from the RPM sensor can be converted to a steady voltage via an Oscilator Controlled Voltage circuit and subsequently read by an ADC, scaled and displayed.
Using an ADC might be a bit more complicated than nessesary for what your trying to do, and even this solution will be degrated a bit
monitoring a:
POT,
Thermocouple,
RPM,
and oil presure switch/sending unit,
Calculating the different values,
and controlling an:
LCD
Servo
& Relays
But i believe this would be alot faster than using the RCTIME comand giving you almost real-time measurements and control.
And i'm not entirely sure but i think most servos (espesially Digital ones) require a steady stream of PWM or else they may become "twitchy" which might not be tollerabe by the turbine engine.
Let's see some pics of this awesome contraption!!
PM me if your interested in a schematic on how these would go together. I like visiting the forums, they help me look at problems in a new way. Beats banging your head up against the wall until you figure it out.
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Definetly a E3 (Electronics Engineer Extrodinare!)
"I laugh in the face of imposible,... not because i know it all, ... but because I don't know well enough!"
Post Edited (RinksCustoms) : 7/6/2006 7:01:05 PM GMT
If so, DO NOT run your overspeed or your throttle directly from a BS2. For a couple hundred you can buy the correct aftermarket gov with overspeed protection and the ability to control the throttle with a pot. This pot could be converted to digital and controlled by a BS2. Everything else is a matter of circuit design.·The LM2907 might be a good choice for your magnetic pickup. Keep in mind that a magnetic pickup can be nasty with voltage spikes and cannot directly interface with the stamp. You can split the pickup signal and share it with the gov and the stamp so you have your read out.
FWIW, the T-62 can overspeed and explode in the blink of an eye. Many have been injured by this little turbine.
I have owned 3 turbines and all had automated start sequences.
Post Edited (Eric R) : 7/7/2006 4:18:43 AM GMT
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·
Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Shawn
Shawn
·· The link doesn't work, since it appears to have been copied from within your My eBay section.· You should copy those URLs from the auction page itself.· Take care.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Shawn
I am new to this forum and I am having a little trouble finding my way around and POSTING , were to POST etc.
Anyway, I am experimenting with engine control and want to use a basic stamp11 to control a 2 cycle 50 CC motorcycle engine. I want to convert this engine to fuel injection using either a Ficht injector or standard low pressure fuel injector as used on most cars. The new 2 cycle scooters have fuel injection and there are conversion kits being produced for Asian TukTuks and motorcycles but that are not available in North Amercia.
These units control fuel injection, spark control, Air for scavaging, Air for combustion, Oil injection or Oil Pressure.
Gain is 80 % in fuel saving, 20 to 50 % in horsepower, smoother runing , Meet Califoria emission laws. All with a 2 cycle sleave valve engine.
I need Computer Control or ECU for this engine project. any Help would be greatly appreciated.
Thanks George .
Basically using Pulse out commands to drive the injector.
Maybe someone has a link to the other thread!
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·
Steve
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Shawn
Post Edited (Shawn Mack) : 7/9/2006 5:12:12 PM GMT
I would not use a basic stamp for this application as there are more than one critical areas that need to be monitored and controlled. While others may disagree with me, I base this on the following. You are expecting the basic stamp to perform the following without including the start and run solenoids, ignition and starter solenoid.
1. Monitor RPM
2. Check for overspeed (emergency shutdown)
3. Control the throttle actuator
All three have priority and are tightly dependant on one another. This doesn't even allow for any cross checking or supervisory monitoring that will check the processor status / health. You should include a set / reset bit with a timer just to make sure your processor has not hung. Keep in mind this Solar is far from a toy and will explode with the force of a Colt handgun if a overspeed is not caught in time and with this little guy that isn't very long.
I will get off my soapbox now and make a recommendation. I think this would be a perfect project for the new Propeller processor. Fire a cog for each critical process and use a cog for supervisory control / monitoring. At least if for some reason a critical cog were to halt, your supervisory cog will likely catch it.·
Shawn
HI Shawn
I think this discussion could be moved on the forum, many other could learn or teach different tecniques to solve the different aspects of this todo list.
For what concern the magnetic pick up, it's important to understand what type of signal is generated (pulses, frequency, analog variations, etc.)and the level of that signal (ttl, cmos, arbitrary voltage levels). Based on that, the circuit and the method of counting the RPM, will be different or require interfaces circuits.
There are basically two methods:
- using the count command, e.g. COUNT Pin, Duration, Variable in wich the command is followed by the pin parameter, the duration (e.g. 1 second or 60seconds/1 minute for directly relate to the units of time used for representation). Pros, symplicity, it's mentally more straigth. Cons, less accurate, some pulse arriving in the ending of the duration, misinterpreted pulses, general noise in the circuit.
- using the pulsin command to measure the "period duration" of one pulse from the magnetic pickup ( if we know that at 1000 hz the period is 1ms. knowing the duration of the period, let us to directly relate to frequency Frequency = 1/period. Pros, higher accuracy, provided the math is high level, higher repeatability, higher speed of completion of the measure. Cons, result more complicated to achieve, more high level maths required (to pass from period to frequency, it's important to deep the calculation to several decimals, not so easy with micros, BASIC Stamp included).
Also it could be necessary to do several readings and mean the result, to get off of eventual ripple (imagine if there's one or more parts of the turbine that has some resonance, this will end in a frequency wobbling and it could be used to raise some sort of alarm) But this comes after............................................For the percentage calculation, it could be done by math or with the use of a table with LOOKUP/LOOKDOWN commands. Also in this case, the latter being the quickest but with the drawback of varying time of completion.
Start to lay down the logical process (of only one work at a time e.g. the measure of the frequency) you want to be executed, then try to solve it block by block, function by function.
When you've done with the above, transform it in a routine in order to get it mixed with the rest of the program in a meaningful way.
Same for the LCD.
The control of the valve it's done simply trough a power mosfet driving directly the valve. Have a look in the Parallax books, that You can find at www.parallax.com/html_pages/downloads/siccurriculum/documentation_sic_curriculum.asp
I suggest You to read broadly the followings, "Applied Sensors 1.3", "Industrial Control".
I learned a lot by these two. The rest has to be done by the old and always valid experimental method of direct hands on, (I simulated the pickup of my engine firstly with a frequency generator, after with the sensor looking at one fin of a fan, and driving the fan different speeds).
Also, it could be easyer and more direct to use proportional relations instead of proper maths calculations ( if i trhust the reliability, repeatability and the linearity of my pickup, i could say that if i read 65000 it is the maximum 2246 Hz hence it is 110 % or whatever units is desired. This eases the use of tables with the commands LOOKUP/LOOKDOWN. The concept is direct table compare and decide.
For the stepper motor controlled by a pot and controlling the throttle, is the same, have a read to the litherature(there's a lot on Parallax site and links), do adaptation of the program and the development of the hardware by steps until You reach the desired result, then transform it in a routine to be mixed in the rest of the program.
The power supply should be not an issue, there's a lot in Parallax forums as well as in the web, in general look for an automotive graded power supply schematic, if efficiency is not an issue, a linear regulator will fit, if it's, a switching type has to be adopted.
At this point (once You've finished all the single parts of the project) will be necessary to extract the requirements, number of pins, speed, memory allowance, etc. to arrive at the choice of a device.
What You are going to accomplish is not a simple project, involving potentially dangerous activities.
So be extremely carefull, attentive and methodic.
For the materials to order, I use the Professional Development Board, but with a bit of imagination, the Boe will suffice, and for the chip, I think the BS2p24 is a good choice for starting.
For the near future, having to move exstensively in Croatia, I will have poor or no internet connection so my answers may be sporadic.
Warmest Regards
Stefano Caruso
P.S. a bit of humour May be I'm becoming a Guru? awake me it's a nigthmare.