Thinking by Wire

I love almost everything about my (relatively) new Subaru car. Lots of the up-to-date electronic stuff is getting to the “can’t live without it” level – anti-lock brakes and traction control, as but two examples. One refinement I could definitely live without is the “throttle by wire” system in place. For the completely non-technical person, it works like this:

Instead of a mechanical linkage between the gas pedal and the throttle assembly, there’s a mechanical linkage only from the gas pedal to a computer. The computer monitors your pedal “inputs” and decides how much throttle it ‘thinks’ you want, and delivers instructions to the electronic fuel injection system for that much fuel to be delivered.

Nothing wrong with that, in theory; in practice, there’s plenty (potentially) wrong with it. Mechanical linkages, by and large, if they’re properly engineered, can reflect subtle gradients of increased or decreased demand (or “load”), particularly as the operator gets used to the ‘feel’ of the linkage. The throttle by wire system seems to monitor inputs in a much more “all or nothing” basis – often too little or too much at a time. Unfortunately, the sequence is often: too little; too little; too little; WHOA! (too much).

If this was only about me getting used to the throttle idiosyncrasies of my car, it wouldn’t be such a big deal. I mean, I’m coping just fine with the quirks. But think about this: Entire airplanes are built around the notion of computers interpreting all of the operator inputs of the pilots. There are hundreds, if not thousands, of interpretations required to determine exactly what the pilot wants at any given moment.

No doubt there are varying levels of urgency to the maneuvers¬†expected of an airplane. Given my own experience ¬†of how the throttle decisions on my WRX work, I’m increasingly skeptical about having computers interpret what humans want from their inputs, particularly when the urgency meter touches ‘extreme’.

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