Drive by wire (cars), or fly by wire (airplanes), is a system in which there are no direct mechanical or hydraulic links between the controls and the hardware. In many newer vehicles, when a person steps on the accelerator or the brake pedal, or turns the steering wheel, or shifts gears, all that happens is that a signal describing the desired input is sent to a computer, which then sends a command to activate the brakes, open or close the throttle, or turn the wheels according to the degree of input from the driver.
Until quite recently it was easy to find the throttle cable, see the steering column poke through the dashboard, etc., and actually see where those things were attached to the rest of the car. It was simple, tried and true direct mechanical linkage from the user to the hardware.
Now, let me ask you something. Why would anyone want to mess around with a system that was a brilliantly simple, proven to work for long periods of time, and would even often work when there was no sound reason for it to do so. A few old friends’ cars come to mind....
Have you seen how tightly everything is packed under the hood of the average car these days? There simply isn't the room to have a straight 3 foot steering column jutting out at an angle from the driver to the steering linkage. But it isn't only that.
Making vehicles with better fuel efficiency often means looking for ways to make them lighter. All the old-fashioned parts that used to manually link driver inputs to the mechanisms that would accomplish what the driver wanted to do could be removed if the controls were routed through a computer, which could then send a signal to a gear box or other apparatus right above the mechanical part.
From an engineering point of view it's a brilliant solution to both lowering the weight of the vehicle and maximizing space usage under the hood. Computers always do what we want them to anyways, right? Uh huh.
If you've never experienced computer hiccup, delay, the occasional inexplicable problem, then you are almost unique. Now link 30 computers together, give each of them its own primary purpose, and have them drive your vehicle. How likely is it that there will never be any problems?
If one of the computers in your car goes haywire, no amount of pressing on the brake pedal is going to help, because the commands are not being delivered by you to the brakes, but rather from you to the computer to....where, nobody knows.
Add to that the fact that in many parts of the world humans live in an invisible sea of (mostly human generated) electromagnetic and radio waves. For the most part their effects are minimal, but if you don't believe they have any effect at all, first see if your vehicle still has AM radio. If it does, find a station and drive around some high tension power lines. The station will disappear in a sea of static.
For almost three years, I didn’t have a case for my computer. My main board, CPU, hard drive….were all exposed. Every time there was a thunderstorm, it would spontaneously shut itself off. Yeah, risky stuff to those who know, but it was my computer, and parts of it still live on in the system I am using now.
I’m all for keeping some things simple, when simple makes sense. Electronic windows always irritated me because there is no manual backup. At the moment, there is no backup plan in many new vehicles if the computer has a hiccup, or can’t decide whether to follow user inputs or follow the computer code written by software engineers in a safe office somewhere.
Some car manufacturers say that preferential treatment is given to the brake pedal if a driver is pressing it, and the throttle is stuck open. Toyota obviously didn’t do this, or it wouldn’t be having such a glorious train wreck in front of the world.
This wasn’t really about Toyota, or taking a cheap shot at them. I’ve never driven a Toyota, but have had Ford and Chrysler products, and have learned to enjoy the quirky personalities the vehicles take on as they age.
Nevertheless, for those who are interested, and despite previous Toyota claims that they haven’t been able to duplicate the runaway car problem, it seemed quite easy for the professor in this video to simulate the event:
Auto Professor Pinpoints Possible Car Flaw
Expert says electronic design flaw is linked to runaway Toyotas.
http://abcnews.go.com/Nightline/
No comments:
Post a Comment