Originally Posted By: wapacz
Originally Posted By: ShiningArcanine
Originally Posted By: Kiwi_ME
Originally Posted By: ShiningArcanine
.. the sudden acceleration issues are most likely the result of the drive by wire transition Toyota is making at the moment. Having drive by wire meant that physical constraints that a mechanically linked system placed on the design of things were lifted, so engineers were free to do things that they could not do previously.
Although DBW is just another firmware control loop in the ECU just like half a dozen other systems. I would expect the engineers that code this stuff would be quite expert at their jobs, and quite possibly don't even work at Toyota but rather the ECU supplier. Given the urgency of the situation and the amount of raw data I'm a little surprised they have not narrowed down a cause.
One company I worked for years ago sold production machinery to Delco. A very similar safety-related firmware issue arose and our marketing department actually had the nerve to try and sell a solution to them as a product "upgrade." As you can imagine that got their lawyers all excited.
I am a computer science major and not an electrical engineering major, but from what I have read the sudden acceleration issues are all of mechanical origin, at least that is what the information describing the recalls says. The transmission issues they had 3 years ago originated in the firmware.
Either way they need to update the firmware to have a break override built into it. From my understanding they are one of the few or possibly only ones that don't have this safety measure built into there drive by wire vehicles. As at full throttle the break boosting abilities are diminished.
Also you do have to admit as a CS major you know how easy it is to have a little bug that can come up and cause major problems.
I will definitely agree that it is easy for little bugs to exist in software that cause major problems, but I am not sure if having the brake override is a good idea. The operation of the brakes and engine have been separate for decades. In driver's ed, they tell you that when you are stopped on a hill, you should hold down the brake with your left foot and then press the accelerator with your right so you do not roll backwards when you release the brake. Simply programming the car to ignore the accelerator when the brake is engaged would prevent that from working.
There is room to have a mph threshold in the code so it works properly, but that is not in the specification which people are saying should be given to Toyota's programmers and I do not have faith that a typical programmer would realize the issue before implementing it. If the change is made, I would not be surprised to hear about an increase in the incident rate of Toyota vehicles colliding with cars because they rolled backwards on hills.
I think adding that as a feature could mask the extent of the underlying problem. If cars were designed like software is designed, there would probably be an option added so the person using the car would decide whether or not this feature is enabled. Then again, if I were making such decisions, I would never have changed the cars' interior and exterior designs, such that in the event of issues, the factories could go back to manufacturing the previous generation models so there would be no pressure to keep selling affected models while engineers figure out what the problem is.
To be honest, if I were in charge of decisions at Toyota, I probably would never have changed the car interior and exterior designs. Between my 1995 Toyota Avalon and my mother's 2008 Toyota Avalon, I think my 1995 Toyota is better designed, for the following reasons:
- The steering wheel is designed in such a way that your hands can freely grasp the 9 o'clock and 3 o'clock positions.
- The view through the rear view window is much deeper and allows you to see more of what is behind you when you back up the car.
- The parking brake has a release mechanism separate from the actual pedal, which ensures that there is no mistake as to whether the brake has been applied or not.
- When the vents are closed, they stay closed, which is better for allergy sufferers such as myself.
- The air conditioner is easier to operate.
- The stick shift is simpler to use.
I listed them in order of greater severity to lowest severity. My mother agrees with me on these points. I can see why some of the changes were made (adding x feature to remain competition on paper required some of these things), but I really do not think appropriate thought was given to their implementation. The various annoyances that the newer model has to me suggests that priorities in Toyota's engineering process have changed; I wish I could speculate on what those priorities might be, but I honestly have no idea. :/
Anyway, now that I have gone off on that tangent, in summary, I do not think modifying the firmware for this is the best idea in terms of design. As far as damage control, now that cars with such an issue are on the market, it is probably the best thing Toyota could do, but I do not think that vehicles should come that way from the factory. I find it difficult to put into words, but my impression of such a feature (cutting off the engine when the brake is applied) is that it will negatively affect a vehicles' predictability, particularly because hiccups where acceleration does not occur in a predictable fashion will go unreported, leading to decreased predictability as time goes on.
