swaaye said:
So what does the ECU on modern vehicles do to optimize the engine for the environment? And, how much does it influence shift patterns? This stuff is very fascinating but it's hard to figure out where to discuss it.
Lots of stuff!
The latest ones have a Motorola PowerPC @60MHz inside. What's being monitored the whole time: ambient temperature, several temperatures inside (oil, coolant, exhaust, gearbox), absolute geographic height, angle and spin of the car, throttle position, gasoline temperature and pressure and so on and so on. Other devices monitor their own sensors and actuators and send lots of stuff over the network (CAN bus). For instance, engine ECU calculates the vehicle speed with wheel rpm being sent over CAN from the ESP (which has wheel sensors hooked up to it).
But it would take like 20 pages just to explain the most basic functions, there are anywhere between 30 and 60 ECU's in a modern car (ECU being "Electronic Control Unit"), each of these with lots of stuff hooked up to them. There are different fallback-strategies in case of failure and a very advanced network management (all configured nodes have to be present and signal their state changes like awake, ready for sleep mode, power down,...). This is in another layer in terms of networking and is independant of "normal" communication although it all runs on CAN concurrently. And then there is a separate diagnostic bus going into the "Central Gateway", which has all the busses running through it and distributes different signals between them.
You have separate ECU's for pretty much everything. Let's take a usual S-class Merc: engine ECU, gear switch module, front/rear relais/switching module, door modules, seats with/without memory, airbag control unit, ABS/ESP/brakes, AC, switch modules, power management for the battery, gasoline pressure control driving the pump(s), ambient light control, rain/light sensors with a control unit for automatically managing the wipers/lights, air suspension ECU, Pre-Safe ECU, parametric steering, sound system, navigation, telephone unit, instrument cluster (is also a gateway), antenna amplifier module, and so on.
Lots of stuff happening in the car all the time. And the customer should never notice anything, just feel comfortable. I think people would think differently if they knew how much of what happens in the car is pure electronics.