MG Kidnaps Driver
Discussion
CT05 Nose Cone said:
Surely even in an EV the mechanical power of the brakes would be stronger than the battery.
Well quite, and it's not exactly a powerful car. So either the story is made up, or the car had two failures simultaneously - a mechanical brake failure and some sort of motor control software failure. bigandclever said:
"sounded like break pads " is bad enough, but I can't work out what Brian-the-s
t-driver's missus was going to do when he "initially called his wife in a panic to ask her to warn cars ahead of him that he could not stop his car".
Brian is clearly a ft-driver's missus was going to do when he "initially called his wife in a panic to ask her to warn cars ahead of him that he could not stop his car".king moron. Also whoever wrote that article needs to be told they're unsuitable for journalism.Ham_and_Jam said:
We must be mere moments away from Brian becoming the new Ron 
CT05 Nose Cone said:
Surely even in an EV the mechanical power of the brakes would be stronger than the battery.
If you tread on the brake properly and bring the car to a halt within a few seconds then yes, but if you're dragging against them for a while deciding what to do while the car is fighting you then it won't take long for the brakes to fade and lose the ability to stop the car.Obviously if you let them cool down for a few minutes and have another go then they will be fine again.
kambites said:
I'm pretty sure true brake-by-wire could not pass European type approval. Primary control systems must have mechanical backups for now.
Brake by wire is perfectly legal and is in widespread production. Current systems do still have a hydraulic backup but this is more about cost effectiveness and reducing complexity for redundancy than it is about legality. I'm not aware of any regulation that specifically prohibits fully decoupled braking systems although I work in more research oriented stuff.The relevant standard is ISO26262 which covers functional safety in automotive electronic systems, it's perfectly possible to create a full by-wire system that complies with this, however it would require top to bottom redundancy and it's easier and cheaper just to leave the hydraulic backup in place.
kambites said:
Fair enough but the fact remains that no-one has done it - there are no EU type approved cars without a mechanical link between brake pedal and brakes.
Not yet no, but if the BBW system hasn't detected a fault then it won't revert to the hydraulic backup. A well engineered system might have a thermal model and a restriction for the drivetrain (cut the engine power when the brakes are too hot) but it's not a requirement.That said I struggle to believe stories like this, there is so much work and detail that goes into compliance and there are so many different incomprehensibly rare things to go wrong independently at once for something like this to happen that it makes it all but impossible.
Even with a software hijack I'd be staggered if the coding allowed for the driver brake input to be overridden so it really comes down to whether it really was an undemanded acceleration and the guy cooked the brakes before they stopped the car or if he's just making it up.
Even the undemanded acceleration would require MG to have flagrantly ignored ISO26262, which admittedly isn't out of the question. They wouldn't be the only EV manufacturer to be fast and loose with it...
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