Quote:
Originally Posted by davew
I think you have it backwards, self driving cars have ALL the technology conventional cars do, plus a whole bunch more.
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That would have sounded better.
I am pretty sure most or all of the motion control systems are closed loop where everything executed is feedback through a servo drive or like device to a main CPU. An example would be when the wheels are turned 15 degrees for a duration of 2 seconds to make a lane change a set of rotary encoders or like devices will feedback exactly what happened. If the command was not executed correctly because the car ran through a pot hole the instant the wheels started to turn a second command will be sent to try to compensate.
Positive of this type system they are highly accurate when they function correctly. Drawback, if anything corrupts the feedback system as simple as a dirty or loose connection it will shutdown the whole system all the way back to turning off the main CPU. So what does the car do when a closed loop servo system decides to shut down operations? Does the car slam on the brakes even if it was going 70 MPH on the freeway? Does it roll to a stop with no steering like a rudderless ship? It isn't if these systems will have issues, it is when.
Open loop systems are way less complicated and have less components therefor not as prone to shut down type failures as closed loop. They basically work like this. A stepper motor is told to turn the wheels 15 degrees for two seconds. It is assumed that is what happened, there is nothing that checked that it was executed correctly. Even if the command was not executed correctly all systems are go, nothing is shut down unless of course the poorly executed command caused a mechanical crash and a limit switch or like device was energized.
