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Have you read the NASA investigation of the Toyota’s unintended acceleration accidents? It’s millions of lines of not properly tested spaghetti code. But I admi

by 2rsf 3y ago

Have you read the NASA investigation of the Toyota’s unintended acceleration accidents? It’s millions of lines of not properly tested spaghetti code. But I admit that it mostly worked pretty well. Unfortunately modern cars are significantly safer than vintage ones so we are stuck with complex software for better and for worse

_yb2s 3y ago
I have not, but if I remember correctly, it ended up being a physical problem (floor mats) and not a software problem? Most vehicle ECUs are traditionally made with very simple C or assembly software that simply maps inputs to outputs via a lookup table... and the same basic ECU firmware is used for decades and shared by numerous car manufacturers (e.g. almost all cars use BOSCH fuel injection ECUs). If they have a complex algorithm or model to generate these tables, that code never goes on the ECU itself, to minimize the complexity and make it reliable and predictable. So the car manufacturer doesn't even develop any code, they only produce a table of numbers for flashing into the ECU, eliminating the possibility of algorithm errors. Once you physically test in diverse conditions that hit every possible value in the lookup table, there is very little room for an unexpected problem to pop up later on. Recalls updating the ECU tables have been mostly to reduce emissions and improve performance, but the vehicle still works fine under all conditions without it. One thing I find really fascinating, is that old fashioned diesel engines had a mechanical injector pump, which was basically a sort of simple mechanical computer that in some sense works the same as described above. All vehicles pretty much used the same pump, but each had different "lookup tables" physically machined into a steel block as a curved ramp. I like the philosophy explained in this article, that mentions Dieter Rams thoughts on the Porsche 911 design: https://www.classicdriver.com/en/article/design-furniture/minimalist-functionalist-influential-designs-dieter-rams https://www.classicdriver.com/en/article/design-furniture/mi... I don't buy the idea that this philosophy can't be applied to make safe and modern electric vehicles.

by 2rsf 3y ago

_yb2s 3y ago

I have not, but if I remember correctly, it ended up being a physical problem (floor mats) and not a software problem? Most vehicle ECUs are traditionally made with very simple C or assembly software that simply maps inputs to outputs via a lookup table... and the same basic ECU firmware is used for decades and shared by numerous car manufacturers (e.g. almost all cars use BOSCH fuel injection ECUs). If they have a complex algorithm or model to generate these tables, that code never goes on the ECU itself, to minimize the complexity and make it reliable and predictable. So the car manufacturer doesn't even develop any code, they only produce a table of numbers for flashing into the ECU, eliminating the possibility of algorithm errors. Once you physically test in diverse conditions that hit every possible value in the lookup table, there is very little room for an unexpected problem to pop up later on. Recalls updating the ECU tables have been mostly to reduce emissions and improve performance, but the vehicle still works fine under all conditions without it. One thing I find really fascinating, is that old fashioned diesel engines had a mechanical injector pump, which was basically a sort of simple mechanical computer that in some sense works the same as described above. All vehicles pretty much used the same pump, but each had different "lookup tables" physically machined into a steel block as a curved ramp. I like the philosophy explained in this article, that mentions Dieter Rams thoughts on the Porsche 911 design: https://www.classicdriver.com/en/article/design-furniture/minimalist-functionalist-influential-designs-dieter-rams https://www.classicdriver.com/en/article/design-furniture/mi... I don't buy the idea that this philosophy can't be applied to make safe and modern electric vehicles.