51–60 of 91 posts
> First, the skateboard and the upper body could be built separately. Maybe not at the same place (a handful of skateboards will fit perfectly in a shipping container for completion thousands of miles away). I hate to be critical, but this really reminds me of a 1950s "visions of the future" piece more than a practical design choice. For example, the skateboard is not a new concept [1], and there are reasons you don'…
Ownership of the car won’t be necessary. As a passenger car sits idle 95 percent of the time, there are plenty of alternative options. Every time I see someone say "all cars will be rentals in the future" I think if all the people I know who have stuff kicking around in the trunk that they use occasionally but rarely. The automotive version of "every-day carry". Some of it's basic car maintenance stuff. Some of it's…
> That will require a major overhaul of technologies like the above-mentioned CAN-bus that is four decades old and employed in every car (including, believe it or not, in a Tesla). I don't understand why the author keeps banging on about CAN bus being an old standard. So what? CAN bus is used in the automotive industry because of it reliability and low wire count. Why should it be changed?
I always downgrade people in my estimations when I see they correlate old with being bad without a good reason.
> First, the skateboard and the upper body could be built separately. Maybe not at the same place (a handful of skateboards will fit perfectly in a shipping container for completion thousands of miles away). I hate to be critical, but this really reminds me of a 1950s "visions of the future" piece more than a practical design choice. For example, the skateboard is not a new concept [1], and there are reasons you don'…
Not knowing anything about how a car is actually built... how does the "skateboard" concept differ from what VW has in their modular platforms? For example: https://en.wikipedia.org/wiki/Volkswagen_Group_MEB_platform It is a difference of just how independent the "skateboard" is from the top?
A true skateboard would be a static implementation of the frame and propulsion system, with defined interfaces for the "top hat" (industry term for the body of the vehicle).
> That will require a major overhaul of technologies like the above-mentioned CAN-bus that is four decades old and employed in every car (including, believe it or not, in a Tesla). I don't understand why the author keeps banging on about CAN bus being an old standard. So what? CAN bus is used in the automotive industry because of it reliability and low wire count. Why should it be changed?
I always downgrade people in my estimations when I see they correlate old with being bad without a good reason.
> That will require a major overhaul of technologies like the above-mentioned CAN-bus that is four decades old and employed in every car (including, believe it or not, in a Tesla). I don't understand why the author keeps banging on about CAN bus being an old standard. So what? CAN bus is used in the automotive industry because of it reliability and low wire count. Why should it be changed?
Because Flex Ray is better for real time systems and has been around over 10 years. Don't get me wrong, CAN and LIN have their place but CAN has a lot of jitter, especially in a car when you can kinda guess how often an ECU is going to spit out messages to the other ones. The only thing you lose with FlexRay is now your controllers have to speak flexray, which is a more complex standard.
Traditionalists like to point to its latency guarantees, but you can do just as well with a thoughtful Ethernet implementation. And there are single pair PHYs. Others argue in favor of the multidrop topology, but I see it as a common failure point. Plus it erodes the utility of the bandwidth.
For multiple drops I like CAN a lot better.
> That will require a major overhaul of technologies like the above-mentioned CAN-bus that is four decades old and employed in every car (including, believe it or not, in a Tesla). I don't understand why the author keeps banging on about CAN bus being an old standard. So what? CAN bus is used in the automotive industry because of it reliability and low wire count. Why should it be changed?
CAN is great for real time control, and a huge number of embedded components support it. I don’t see it going away any time soon. That said, it does not have a lot of bandwidth. There will need to be something higher bandwidth to support modern info-tainment systems. A second, high-bandwidth network with less strict real-time requirements.
> That will require a major overhaul of technologies like the above-mentioned CAN-bus that is four decades old and employed in every car (including, believe it or not, in a Tesla). I don't understand why the author keeps banging on about CAN bus being an old standard. So what? CAN bus is used in the automotive industry because of it reliability and low wire count. Why should it be changed?
I don't know this space, but depending it may be there are more messages going to and fro, and so perhaps more bandwidth is desired? IEEE 1394 ("FireWire") seems to have a bunch of 'industrial' uses:
* https://en.wikipedia.org/wiki/IEEE_1394#Common_applications
The marine folks went from a CAN-like NMEA 0183, to a more bus-like NMEA 2000, and are not looking at an Ethernet-based system:
* https://en.wikipedia.org/wiki/NMEA_2000
* https://en.wikipedia.org/wiki/NMEA_OneNet
If all you're doing is getting sensor values at a few Hertz, then CANbus is probably fine, but if you need to distribute the images of a read-view camera, a bunch sonars, a bunch of radars, etc, then the 500 kbit/s in J1939/14 may not be enough.
Even the 'CAN folks' recognize this:
But can be refilled in 5 minutes and driven for 300 miles, which I don't see happening with electric cars any time soon.
Earlier quoted context omitted.
I definitely don't want people to "hack" their cars and drive on the same road as me.
"Hacking" of cars has been always extremely popular, and you share the roads with people who modify their cars every time you drive. Why should that change now?
If you write your own DIY electric power steering firmware, and it crashes or gets stuck it can just suddenly fail on the road and you're dead.