Articles“Now, children, check out this vintage car. How old do you think it is?”
“It was made before 2015, Miss!”
“That’s right, Garl. Why don’t you tell the rest of the class how you knew that.”
“Because it still has an old Go lever, Miss!”
“That’s right! That Go foot-lever used to be called the ‘accelerator pedal’. The military made sure that manufacturers removed those from cars after the Usability Wars of 2015. Can anyone guess what pressing the accelerator pedal down to, say, half-way would do?”
“Miss! Miss! Did it get you halfway to your destination?”
“No, Hrum. Tools weren’t goal-oriented back then – even the expensive, sophisticated ones, like cars. The drivers had to adapt to the abilities of the car. Who wants to have another try?”
“Did it make the car go half of its maximum speed, Miss?”
“Good try, Kwel. Getting closer!”
“Ooh! Halfway must be stop! Further down is forward, further up is reverse!”
“Nice thinking, Kwel! But that might be tricky find the stop position in a hurry. Anyone else?”
“Hmmm… it’s called an ‘accelerator pedal’, right? So it must accelerate at half of its maximum acceleration? Taking your foot off the accelerator would mean cruise at the current speed! To slow down you’d hit the stop lever!”
“The stop lever is called the ‘brake pedal’, Laos, and I’m afraid the ‘accelerator pedal’ is poorly named. Some people called it a ‘throttle’ instead – does that help?”
“Throttle, Miss? But surely a throttle would slow you down?”
“Okay, let me explain, children. The pedal controlled the amount of fuel to the engine. But it wasn’t that simple. Halfway didn’t mean half of the maximum amount of fuel was getting through. The amount of fuel actually getting through the throttle was related to the accelerator position and the speed of the car… no wait… the speed of the engine which is related to the speed of the car, but depends on the gear selected. So then the amount of fuel that reaches the engine affects the final speed (depending on the level of drag, which is proportional to the square of the velocity) and it also affects the acceleration to get to that speed.”
“Wow, that must have been hard to pilot, Miss.”
“Yes, it was – it took lots of practise before the relationship became clear. But people didn’t realise back then that there might be a better way. They just used the same systems their parents, and their parents’ parents, and their parents’ parents’ parents used.”
“And is that how the Usability Wars started?”
“No, no that wasn’t the only reason. But it played a small part.”
Comment by Alastair on September 20, 2006
So maybe I’m going to get a “D” from the teacher, but…
The way I understand it, the throttle controls a butterfly valve in the throttle body which lets air in. Halfway on the pedal equals halfway open. How much fuel is used depends on the airflow through that valve which, as you say, depends on other factors.
I can’t see what this has to do with usability. Press accellerator, go faster; where’s the usability problem exactly? Just because it’s not easy to *explain* the operation of the car, doesn’t make it unusable. How many learner drivers fail their tests because they can’t figure out the accellerator?
(Now if you want to talk about how friction points on a clutch pedal are never in the same place twice, I can probably see the usability problem there…)
Comment by Aristotle Pagaltzis on September 21, 2006
Nice theory that it’s a usability issue. Unfortunately, cars operate in something called our Universe which has a law of physics that’s called inertia.
Cars weigh roughly 1.4 tons on average, and move at speeds of typically 10-30 m/s. Any force to accelerate it in any direction can only be applied through a grand total of a few dozen square centimentres, ie the sum total of the area where wheels touch ground. Said wheels consist of rubber and they run on pavement. The engine’s power output is limited anyway, but even if it wasn’t rubber wheels on pavement can only support so much force.
Under these constraints, something like “make the car go at half the maximum speed†is a rather… shall we say, impractical idea, since inertia is a first-class factor in all your decisions. You can’t make the car go to half speed instantly on pressing the pedal half-way down, or stop it instantly when releasing the pedal.
“Half-way to the destination†works better, because it works on a much higher level, but of course that isn’t actually “driving†any more.
It didn’t take me a long time to get a feel for how to operate the pedal, anyway, nor did it seem to pose a major problem for any of the others at driving school.
I couldn’t care less about better controls anyway. I want my flying car!
Comment by Julian on September 28, 2006
I understand that there’s no instant acceleration, but I can set my cruise control to a certain speed and turn it on. It knows what I mean and accelerates at a comfortable rate to that point, and then holds it. We’re halfway there.
Inertia actually is a big problem for another reason: inertia of the driver, compared to the car! The two pedal (accelerator/brake) system has an important emergent safety behaviour.
When you brake hard, you tend to fly forward (relative to the pedal). It is a a positive feedback system, and you slow down further. When you accelerate hard, you tend to fly backward, with is a negative feedback system – you slow down further.
In any case, I think the common argument from Aristotle and Alastair is a strong one: it’s not much of a problem and doesn’t take longer to learn. It is a tough one to argue.
My best response to that is to gather a team of usability experts and engineers and build a small fleet of my super-cars. Then we will train two sets of drivers – one in the new system and a control group using the old system. We’ll watch them for a few years. When you see the staggering improvements in the time taken to learn to drive, the lower fuel consumption, the reduction in accidents and the increase in subjective happiness scores, you will be more than happy to admit you were wrong.
Can either of you lend me, say, $10 million for this project? I’ll pay you back when the royalties start flooding in.