On 06/14/2012 09:36 PM, Jon Elson wrote: > Stuart Stevenson wrote: >> It would be easier to purchase a running car with the features desired - if >> you could find one. >> I have not seen a car with open ECU software. There is always something *NOT >> * open even with an aftermarket configurable system. >> Part of the point of the exercise is to have LinuxCNC controlling the motor >> and other functions. >> > Well, the complexity these days is that the ECU controls EVERYTHING! > So, not only > do you have spark and injection, you probably have AC control, emissions > control, thermal > control, alternator regulation, and the transmission as well. And, most > of that stuff will > not be well documented, so you would have to do a lot of trial and > error. It might be > possible to put the transmission in two gears at once and cause gear > breakage, for > instance. > > Jon
An easy solution, would be to have 2 computers. One to run the engine, and another to run everything else. Not a too far fetched idea, considering some of the better luxury cars, have multiple computers, spread out over the body, with multiple 1 wire, and CAN bus sensors, per computer, all talking to a MCP (for lack of a better word). A modern engine, running at a exaggerated speed of say 10,000 rpm's, will be firing 2 coil packs every rotation, or 166.667 times per second, times 2. Only 3 sensors are needed to make this work, a crank angle sensor, with a multitooth sprocket, a cam angle sensor, that is read once per revolution, and a Throttle Position Sensor (TPS). Modern fuel injectors, are basically mini electric fuel pumps, and run non-stop. They run off of a PWM signal, which is altered, based on what the Oxygen (O2) sensors, and the Mass AirFlow sensor (MAF), are telling it. On every 4 cylinder engine that I've worked on (Esp. from the 90's), all the fuel injector operated off of the same PWM signal, which simplified things considerably. The main proponent for doing it that way, is that O2 sensors can only tell that the exhaust stream is running either lean, or rich. They can't really tell WHICH cylinder is causing the problem. So, for the bare minimum to get a engine to run, you would need to read 6 inputs, and 3 outputs, in realtime: The inputs are: crank angle sensor, and cam angle sensor, which is basically a rotary encoder, with index. 1 potentiometer (TPS), and 3 analog inputs, O2 x 2, and MAF. The outputs are: 1 pwm signal, for the injectors, and 1 output for each of the coils. Those sensors, are THE most important sensors on the engine. All other sensors on the engine such as RPM's, water temperature, vacuum, oil pressure, etc... all play a roll, but in a minor capacity, and as such, can be read once every couple of seconds or so. Hardware wise, it's all doable. It's on the software side of things, that everything gets tricky. The air/fuel mixture is fairly straightforward, and runs in it's own loop, independent of everything else. it's leading the spark (advance), based upon the RPM's of the engine, TPS position, and just how lean the exhaust is at that precise time, is where everything gets tricky. And, this isn't even getting into the drivetrain, cruise control, braking, charging systems, ride quality, and environmental control... -- -Mark Ne M'oubliez ---Family Motto Hope for the best, plan for the worst ---Personal Motto ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
