Comment 38743

By zippo (registered) | Posted March 13, 2010 at 14:57:20

On my 5 year old motorcycle there is a carburetor, not an automated fuel injection system. It's throttle plate is opened not by a computer controlled servo, but by a cable connected to the handlebar grip. This is all very similar to most cars of 20 years ago and removes the possibility of software or electronic hardware failure causing "overspeed", but not obviously mechanical failure. Fortunately it does not stop there. The throttle is closed not by a spring alone as in many older cars (those springs did break from time to time causing a "stuck throttle"), but also by a separate and independent cable to the handlebar grip which actively pulls the throttle closed. Now this system can fail, but the approach of such failure is detectable and preventable with simple routine maintenance.

Should this be neglected and failure occur there is then a 2 layer system to remove electrical power to the ignition system; The ignition key switch, which cuts all power to the bike, and a separate and independent "kill" switch on the handle bar which cuts all power to the engine (but keeps power to the lights and horn). Again, unlike the modern car, these switches are not input devices to a computer but simple mechanical devices located electrically between the battery and the engine.

Could all of this "fail unsafe" simultaneously resulting in an unmanageable overspeed? Sure, but I am not aware that it ever has. I'm certainly not losing sleep over the possibility.

We know that no practical amount of testing of a non-trivial software system can prove it to be bug free, only demonstrate the existence of a bug. I think we can also say that it is "very difficult" to construct computer hardware that operates "fault free" for essentially "no money" (the x hundred dollars that the cars engine control computer and sensors cost).

I doubt that adding another layer of software complexity to the computer system is the path to a truly "robust" solution to the problem.

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