5 ms·
On the contrary, adding just "a few meters of cable" per each critical system, and adding separate sensors instead of using the same critical sensors would grea
by fodkodrasz 3y ago
On the contrary, adding just "a few meters of cable" per each critical system, and adding separate sensors instead of using the same critical sensors would greatly increase complexity. Also so really underestimate the cabling and sensor needs for modern requirements.
Having redundant bus and redundant sensors usable by multiple subsystems is a better way.
Well, I have heard of power assist using a single simple potentiometer as a steering wheel position sensor in some really cheap cars... I'm not sure how much of an urban legend that is, but nowadays it surely wouldn't cut it for road permission in the EU.
- jojobas 3y agoCompared to classic hydraulic lines everywhere dedicated cables seem easy. Having to account for a DOS attack from a compromised head unit or some such just seems like a nightmare.
- fodkodrasz 3y agoOn one hand you are right, but only if we can ignore the highly increased risk of electric malfunction from the extensive traditional (non bus based) wiring. This was a common problem in the 1980s when electric gadgets became numerous, but no standard bus was used on many such cars. To overcome this the plan back when I was working on that product was to use 2 system buses, one isolated internal for the safe critical sensor/control network, and one user facing untrusted bus, with a ECU designed to serve as a firewall basically.
- jojobas 3y agoWhy even have the firewall? Wouldn't a true airgap be preferable? At the same time, having say steering and brakes on the same bus adds a single point of failure to both steering and brakes, which is not ideal.
- fodkodrasz 3y agoCost and risk management. These systems undergo rigorous safety evaluation, auditing, and testing. This is a manageable risk (very low) given the business requirements and the threat model.