14 ms·

Rivian reduced electrical wiring by 1.6 miles and 44 pounds

173 points by addaon 2y ago

deleted 2y ago
[deleted]
warkdarrior 2y ago
Couldn't they just use Wi-Fi? So much wiring..
- deleted 2y ago
  [deleted]
- Jtsummers 2y ago
  "just use Wi-Fi?", probably not. I don't think you'd want to create so many openings for attackers. Besides, EMI is a real issue and not something you want interfering with your critical systems too much.
  - dylan604 2y ago
    > EMI is a real issue To the point they are wanting to eliminate AM radio because they've gotten to the point that the uncontrollable EMI makes AM "unlistenable". So move the goal posts, and make AM radio out-of-fashion and get rid of it rather than solving the EMI issues.
    - katzinsky 2y ago
      1) I don't think you'll ever be able to make an electric vehicle electrically quiet enough to make AM work nicely and if you somehow did between the shielding and all the balancing currents there's no way it would be efficient. I like AM radio but these two things are probably never going to be compatible. 2) WiFi really isn't as reliable as a cable. There are all kinds of things internal and external that could cause an outage. Why bother with that when you can just run maybe a dollar of copper to the ECU?
- adrian_b 2y ago
  So that anyone could crash your car with a jammer?
- silisili 2y ago
  Ignoring wifi as a poor use case here(you'd likely use something with much less interference and better latency), RF will still usually have more latency than a wire. It's more prone to interference from other random devices and even other cars. Canbus is typically shielded, which you obviously can't do with something relying on radio. Then you have physical interference...imagine all your warning lights come on, wipers come on, and radio cuts off because your wife put her Stanley in just the wrong spot.
- Gibbon1 2y ago
  People don't like your comment but I have a side project that requires controlling 36 lamps in groups of 3. I rolled it over and I'm just going to slap a cheap radio on a PCB's and just daisy chain the power.
  - kkfx 2y ago
    I've built my "smart home" explicitly without wifi [1] to shield against any kind of "local exterior attack" and mere communication issues due to natural phenomenon. Even for light I decide for ShellyPro 4PM to avoid wireless... Surely without cables it's far easier, but this easiness have a price. [1] with the exception of the car charger since I wasn't able to find a damn cabled one (it's 230Vac, not CCS eh!)
    - nurettin 2y ago
      > "local exterior attack" I appreciate the geek, but is this useful in practice? Does it happen to anyone?
      - kkfx 2y ago
        I do not know any statistic, but for instance https://www.cnet.com/home/security/can-burglars-jam-your-wireless-security-system/ https://www.cnet.com/home/security/can-burglars-jam-your-wir... it's a well known phenomenon, as it's well known enough you can buy a ready-made multi-frequency jammer for very little price from China. Aside another aspect is how to make the home impossible to live in case someone illegally occupy it (here, France, but essentially all south Europe is a relatively new but spread thing) while you are on vacation to be quicker than local authorities. Another one is avoiding connecting too much black boxes to their OEM homes. Another final aspect is mere reliability, as a small anecdote: a neighbor due to some unknown issue have had roller shutters locked down because they have ONLY a wireless remote with a kind of ESP32 inside, all proprietary, no emergency manual opening, no access to the motor to power it directly or detach the break manually on the shutters. My home while "a bit smart" have a far little attack surface in that regard. For instance just to have central/remote lights control I've chosen a set of ShellyPro 4PM (the least expensive option of that kind I was able to find) witch operate remotely (LAN only, via HA or directly logging on the device, extended via wireguard) but i can also operate via classic mechanical switches and internally the Shelly are "dumb classic switch" + extras so if their fw crash from the physical buttons (not the one on the devices, but their normally open contacts) they still operate. For the car charger I'm obliged to go wifi (I find exactly no one domestic charging station with wired connections for control) but it's a dedicated WLAN (a small GL.iNet "stamp" size on the back of the charger, wired to a dedicated port of my homeserver on a completely separated LAN without internet access and the charger itself is MQTT/ModBUS-bridged to its local, internet-less controller/server for p.v. integration. I can't do nothing for my car and well... Sometimes it's "app-service" to remote control A/C etc get connected to someone else car in another country and yes, I can monitor it and act on it when this happen (few times per years so far). No special hacking needed. No response from the vendor (MG/SAIC)... And for cars some demoed serious remote vulnerabilities able to physically make a car crash while running. All those might be very rare events, but their seriousness it's relevant enough for me to avoid them as much as possible.
- daghamm 2y ago
  OP is heavily downvoted, but yes some ECU are moving to wireless communication although not WiFi. It started with places where you simply can't have wires, for example tire pressure monitoring. But is now spreading to other simple ECUs. And yes, it can be jammed so obviously it's not for brakes and steering and things like that.
  - Gibbon1 2y ago
    You can image the drivers side door has a module that senses the door switches and operates the drivers window and door locks. And communicates via RF to modules in the other three doors to control the windows and door locks. Seriously why the heck not? I've thought in the past what I want for trailer lights is a RF connection between the vehicle and the trailer. It can't be worse than the standard way that always fails.
- janice1999 2y ago
  It's a good question. Wireless is already replacing wiring inside the battery pack performing some of the most sensitive data transmission. See here for details: https://www.gm-trucks.com/explained-general-motors-wireless-ultium-battery-management/ https://www.gm-trucks.com/explained-general-motors-wireless-...
- PlunderBunny 2y ago
  If my experience of trying to tether my laptop to my phone on a moving bus is any indication, I'm thinking that WiFi (as opposed to other wireless technologies) is a non-starter.
gorgoiler 2y ago
The before/after ECU layout diagram is very instructional. I like to imagine some kind of engineering “meet cute” whereby, one random day, the headlights engineer and the parking radar engineer happen to be working on the front of the car together. Their eyes meet: “hey, I’m John — I didn’t know you had an ECU here!”, “hi, I’m Claire — wow, you have an ECU right up front too? It’s, like, right next to mine and we never knew!” “I know, crazy right?! Hey this is going to sound really forward and I don’t normally do this but I’m only running at 70% compute capacity. I don’t suppose you need any real-time budget this evening?” “So funny you should ask, I was just about to run a whole bunch of heavy new wiring to…” And in a story as old as time they get ECU married and raise their control loops in the same front-of-vehicle ECU together instead of living their separate, lonely, ECU-right-next-to-each-other-and-they-didn’t-know-it lives.
- jdiez17 2y ago
  I ... am a bit speechless ... I didn't know this was something I could be into so much, and yet here we are.
  - brundolf 2y ago
    That's what they said
- kevin_thibedeau 2y ago
  Ford did this with the cost reduced version of SYNC 3, merging two modules to form SYNC 2.5. The result is an unstable heap of trash.
  - dangus 2y ago
    Well, it is Ford. You buy a Ford you should expect it to be trash.
- plg94 2y ago
  wow, you made hackernews turn into tumblr. Well done, great explanation.
gregmac 2y ago
It's interesting to think about the failure modes here. With domain-based ECUs, a failure means your locks OR windows OR windshield wipers stop working. With zone-based, it could be the entire "west" zone that stops, which means you can't unlock the driver's door, open the windows, adjust the seat, and maybe even the ventilation fans don't work I actually thought a lot of that was already on the CAN bus anyway, but my knowledge of cars stops there so maybe someone can fill in the gaps. Seeing only three "zones" is actually surprising to me. As I was reading I started forming the idea of a single bus cable that went around the car, with I/O modules anywhere there were physical buttons/lights/etc. There would just have to be a cost+weight balance of where it makes sense to stick a small I/O module vs run individual wires back to a bigger module. My assumption is as technology advances it becomes cheaper to have more small I/O modules with very short wire runs to buttons, but it doesn't seem like this is what they're doing. I am also making the assumption this is "dumb I/O", and somewhere there is a "door lock" program that handles all locks/buttons. In the main computer you'd run all the domain programs individually/isolated, but there would still be a single program responsible for each domain, eg: all the locks (eg: considering button presses, fob buttons, door state, moving or not, etc, and act on the locks accordingly). From a pure software point of view, if the east/west/south ECUs are actually doing the logic for their respective parts of the car, that seems like a nightmare to build: the code would end up being all partial and distributed. In the worst case you end up with bizarre bugs like "if you open the passenger door, then open the tailgate, then close the passenger door and press the lock button, the driver's door will lock but the passenger won't until you first unlock then shut everything" (which gets reported as "the locks are unreliable, some will randomly just not work every few days").
- edmundsauto 2y ago
  Some door locks will trigger the servo every time you hit the heron (older-ish cars) and some have a sensor. Not clear to me if it’s a remote sensor or some sort of smarts in the local mechanism. Given some of the chip shortages of recent year, I’m curious how the teams responsible for those trade offs made the balance.
- guai888 2y ago
  Standard approach is following ISO 26262 development to deal with risk resulting from failure mode.
indoorcomic 2y ago
I love this. I hope this more manufactures go this route. I've always felt that having ~100 ECUs in a car is complete overkill.
- Jtsummers 2y ago
  See gregmac's comment, it changes the failure modes and makes what could be isolated subsystem failures larger regional failures. However, components are also becoming much more reliable so this is an engineering tradeoff. Cases can be made in both directions. EDIT: That's not the only tradeoff, but it is a key one.
  - metadat 2y ago
    https://news.ycombinator.com/item?id=41207335 https://news.ycombinator.com/item?id=41207335 In the future, please include the actual link. It is 10x more useful.
- AlotOfReading 2y ago
  I've been a (somewhat successful) advocate of similar approaches at the automakers I've worked for, but it's not as simple as the article makes it sound. Individual components in each "zone" can have different reliability requirements, for example. They also might be produced by different suppliers, or only be present on certain models / trims. Rivian is able to do this because they're taking advantage of modern heterogenous processors and they haven't made the mistake of outsourcing almost all of their software capabilities to tier 1,2,3 suppliers. Legacy OEMs find it much more difficult to adopt, especially once the institutional inertia takes over.
- Ekaros 2y ago
  Replacing word ECU with micro-controller makes number seem less insane. Okay, PCs are having less and less components. But one might ask why do so many components have any logic at all? We got extremely insanely powerful central CPUs with loads of memory and storage space. So why not just do absolutely everything there? Remove any logic and computing from screens, keyboards, mice, SSDs, HDDs, off load everything from network chips and sounds chips. Just move all of it to CPU?
OptionOfT 2y ago
I think having multiple ECUs over time is a cost savings mechanism. You have a module that you can use in all your models because it works. If Rivian wants to add a new feature that doesn't 'fit' on the AIO ecu, then what? Replace it and re-certify ALL of its functions? A good example is the ABS controller which is usually just a Bosch COTS ECU. You wouldn't even want to implement that for yourself.
daghamm 2y ago
"four categories get their own ECUs: infotainment, autonomy, vehicle access, drive units, and its battery management system." Am I reading this wrong, or are these actually five categories?
- masklinn 2y ago
  Given the wording of "drive units, and its battery management system" I'd think the BMS is linked to the drive units and under the same ECU. I'd assume the drive units and BMS are tightly integrated, as that's basically the entire high-voltage system and you have to manage the two-ways energy flow between the two (propulsion and braking / regen).
  - trainsarebetter 2y ago
    Not really, the FOC software that runs on the inverters is compute heavy and safety critical. It gets its own dedicated controller (they are actually running to cpus in parallel in case one fails) and same with the bms. They talk over can currently in teslas. bms states it’s max charge and discharge current, and everything else listens
aaron695 2y ago
[dead]
schobi 2y ago
The diagrams for the new west south and east zones still show a lot of wires going all across the vehicle. This step might be a good first one to reduce the number of ECUs by combining them, but there is still the same cross-car wiring. You still seem to have a single ECU per function, but merged into a few dedicated boxes for example. Next step: Each wire only goes to the nearest box. I'm curious how the Tesla unboxed architecture will eventually play out. I understand that eventually, the ECUs will be split up, so you have some aspect of each ECU in each corner of the vehicle. Part of the "lights" function is in front-left, part of it in the back. Wires only go to the nearest box. A powerful vision, with the potential to further reduce wiring. Complex until you get a distributed brake ECU.
yc-kraln 2y ago
The electrical wiring in cars is Conway's law manifest in copper. For those unfamiliar with Conway's law, I am arguing that how the car companies have organized themselves--and their budgets--ends up being directly reflected in the number of ECUs as well as how they're connected with each other. I imagine that by measuring the amount of excess copper, you´d have a pretty good measure for the overhead involved in the project management from the manufacturers' side. (I previously worked for Daimler)
- mensetmanusman 2y ago
  Would be funny to have a ‘mm Cu / FTE’ scaling law.
  - throwaway48476 2y ago
    Complexity is a function of the number and depth of suppliers.
  - westurner 2y ago
    The ohm*meter^3 is the unit of electrical resistance. Electrical resistivity and conductivity: https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity https://en.wikipedia.org/wiki/Electrical_resistivity_and_con... Is there a name for Wh/m or W/m (of Cu or C) of loss? Just % signal loss? "Copper Mining and Vehicle Electrification" (2024) https://www.ief.org/focus/ief-reports/copper-mining-and-vehicle-electrification https://www.ief.org/focus/ief-reports/copper-mining-and-vehi... .. https://news.ycombinator.com/item?id=40542826 https://news.ycombinator.com/item?id=40542826 There's already conductive graphene 3d printing filament (and far less conductive graphene). Looks like 0.8ohm*cm may be the least resistive graphene filament available: https://www.google.com/search?q=graphene+3d+printer+filament+ohm https://www.google.com/search?q=graphene+3d+printer+filament... Are there yet CNT or TWCNT Twisted Carbon Nanotube substitutes for copper wiring?
    - westurner 2y ago
      * far less conductive graphite; another form of carbon FWIU recent developments in graphene semiconductors for example on silicon carbide are undercapitalized. Can industry undo its unsustainable copper dependency by replacing power wires and data cabling with TWCNT cabling?
lofaszvanitt 2y ago
3rd generation: no wires from sensors to detectors.
- twoWhlsGud 2y ago
  4th generation: wires are back so the car doesn't stop working every time it drives by a source of RF noise...
  - lofaszvanitt 2y ago
    We'll see...
xbmcuser 2y ago
I recalled I read something similar before so I searched for it. It was Tesla doing something like this in 2019 https://electrek.co/2019/07/22/tesla-revolutionary-wiring-architecture-robots-model-y/ https://electrek.co/2019/07/22/tesla-revolutionary-wiring-ar... "In order to facilitate the automation of manipulating cables, Tesla has been reducing the length of wiring harnesses in its vehicles. Musk said that Model S has about 3 kilometers of wiring harnesses and Tesla brought it down to 1.5 kilometers in length for the Model 3. But that’s just the beginning. Tesla is working on a whole new wiring architecture for future vehicle platforms and they aim to bring it down to just 100 meters starting with the Model Y."
- grecy 2y ago
  Tesla have taken it to a whole new level on cyber truck. It is assumed this will continue in their next gen vehicles
  - theluketaylor 2y ago
    The legacy car makers have flirted with 48V components for decades but haven't been willing to do the hard work to realize all the benefits it brings. The germans in particular are stuck in limbo. For their PHEV and BEV cars they are shipping 12V for all traditional functions, 48V for advanced functions like active suspension and anti-roll bars, and high voltage systems for the traction motor. Complete mess. It's frustrating to be a Tesla owner. For every great engineering choice they make like going all in on 48V they make a user hostile choice like removing stalks and selling "full self driving" that is downright dangerous.
    - jvanderbot 2y ago
      The single most frustrating thing Tesla did re: Power was not allowing me to plug an appliance in. We lose power somewhat regularly where I live due to storms, and the tesla has 6-10 days of my household power budget sitting in its banks. Just let me plug in a deep freezer and coffee maker, please. INB4 the 12V terminals: They are hard to access, have limited amps, and are a separate crappy battery.
quanto 2y ago
quick math check > 1.6 miles and 44 pounds pure copper density at 9000 kg/m3, wire diameter assumed at 1mm, length at 3000 m (1.8 mi, approx) gives 21 kg, approximately 46 lb. math checks out. > the company claims a 20 percent savings in material costs and 15 percent reduction in its carbon footprint between Gen 1 and Gen 2. surely this is not just due to the reduction of copper. copper is around 10 USD/kg at bulk. now let's see if we can address the copper length number. can 1.6 mi (< 3000 m) of copper be saved from wiring alone? The car dimensions are 2m x 5m. That means, in the worst case, two ECUs placed at opposite ends will need 5m of wire (half of perimeter). There were 17 ECUs originally. Call it n = 20, and if we wire dense (in the graph sense), we get n^2 = 400. So, in the absolute worst case, the densest possible graph would have had 5m x 400 = 2000 m of wire. The claimed wire saving is significantly (but not by an order of magnitude) larger than this. I would say this passes the smell test (albeit barely), but original wiring must have been truly inefficient.
- spydum 2y ago
  maybe i missed in your estimate, but most circuits need more than one wire?
  - hn72774 2y ago
    In a vehicle, the chassis is the negative wire in the circuit.
    - AlotOfReading 2y ago
      The vast majority of automotive buses use differential signaling over multiple conductors for EMI reasons. The only common exception is LIN and maybe SWCAN if we're exceedingly generous with our definition of "common".
  - caleblloyd 2y ago
    I didn’t completely follow either but I think the n^2 = 400 worked out to 20 ECUs each with 20 wires
thelastgallon 2y ago
Rivian can switch to 48V for more gains. https://news.ycombinator.com/item?id=38576612 https://news.ycombinator.com/item?id=38576612: The move to 48V means much less power is lost (power loss = (IxI)xR ), cables can be much smaller, cables and terminals can be much lighter and much less copper can be used used. Discussion: Tesla shares 48V architecture with other automakers: https://news.ycombinator.com/item?id=38557203 https://news.ycombinator.com/item?id=38557203
- jondwillis 2y ago
  Those are rookie numbers. Let’s bump it up to 96V while we are at it.
  - throwaway48476 2y ago
    50V is the generally accepted safe cutoff. There are separate electrical certifications for 'low voltage' <50V.
    - addaon 2y ago
      SELV is often capped at 60 V, not 50 V, although this is often treated as “48 V with crappy bounds”. An example that takes advantage of this would be PoE, which allows 44 V - 57 V at the PSE; but most PSEs are, in my experience, in the 54 - 57 V range.
      - yencabulator 2y ago
        48 V + charging ends up around 54-58 V, so the 60 V cap is needed for 48 V systems.
        addaon 2y ago
        Only for 48 V systems that have a battery, which does not apply to PoE, and does not apply universally to 48 V automotive approaches (although the CyberTruck does use a 48 V battery).
_heimdall 2y ago
I was expecting to see a mention of whether there were any safety concerns related to running fewer ECUs. I'd assume not since they chose to go this route, but the idea of the infotainment system going down and taking other systems offline with it seems like a risk they would have had to consider.
therealdkz 2y ago
There is nothing like perf improvement that removes sleep() put in earlier…

173 points by addaon 2y ago

deleted 2y ago

[deleted]

warkdarrior 2y ago

Couldn't they just use Wi-Fi? So much wiring..

deleted 2y ago
[deleted]
Jtsummers 2y ago
"just use Wi-Fi?", probably not. I don't think you'd want to create so many openings for attackers. Besides, EMI is a real issue and not something you want interfering with your critical systems too much.
- dylan604 2y ago
  > EMI is a real issue To the point they are wanting to eliminate AM radio because they've gotten to the point that the uncontrollable EMI makes AM "unlistenable". So move the goal posts, and make AM radio out-of-fashion and get rid of it rather than solving the EMI issues.
  - katzinsky 2y ago
    1) I don't think you'll ever be able to make an electric vehicle electrically quiet enough to make AM work nicely and if you somehow did between the shielding and all the balancing currents there's no way it would be efficient. I like AM radio but these two things are probably never going to be compatible. 2) WiFi really isn't as reliable as a cable. There are all kinds of things internal and external that could cause an outage. Why bother with that when you can just run maybe a dollar of copper to the ECU?
adrian_b 2y ago
So that anyone could crash your car with a jammer?
silisili 2y ago
Ignoring wifi as a poor use case here(you'd likely use something with much less interference and better latency), RF will still usually have more latency than a wire. It's more prone to interference from other random devices and even other cars. Canbus is typically shielded, which you obviously can't do with something relying on radio. Then you have physical interference...imagine all your warning lights come on, wipers come on, and radio cuts off because your wife put her Stanley in just the wrong spot.
Gibbon1 2y ago
People don't like your comment but I have a side project that requires controlling 36 lamps in groups of 3. I rolled it over and I'm just going to slap a cheap radio on a PCB's and just daisy chain the power.
- kkfx 2y ago
  I've built my "smart home" explicitly without wifi [1] to shield against any kind of "local exterior attack" and mere communication issues due to natural phenomenon. Even for light I decide for ShellyPro 4PM to avoid wireless... Surely without cables it's far easier, but this easiness have a price. [1] with the exception of the car charger since I wasn't able to find a damn cabled one (it's 230Vac, not CCS eh!)
  - nurettin 2y ago
    > "local exterior attack" I appreciate the geek, but is this useful in practice? Does it happen to anyone?
    - kkfx 2y ago
      I do not know any statistic, but for instance https://www.cnet.com/home/security/can-burglars-jam-your-wireless-security-system/ https://www.cnet.com/home/security/can-burglars-jam-your-wir... it's a well known phenomenon, as it's well known enough you can buy a ready-made multi-frequency jammer for very little price from China. Aside another aspect is how to make the home impossible to live in case someone illegally occupy it (here, France, but essentially all south Europe is a relatively new but spread thing) while you are on vacation to be quicker than local authorities. Another one is avoiding connecting too much black boxes to their OEM homes. Another final aspect is mere reliability, as a small anecdote: a neighbor due to some unknown issue have had roller shutters locked down because they have ONLY a wireless remote with a kind of ESP32 inside, all proprietary, no emergency manual opening, no access to the motor to power it directly or detach the break manually on the shutters. My home while "a bit smart" have a far little attack surface in that regard. For instance just to have central/remote lights control I've chosen a set of ShellyPro 4PM (the least expensive option of that kind I was able to find) witch operate remotely (LAN only, via HA or directly logging on the device, extended via wireguard) but i can also operate via classic mechanical switches and internally the Shelly are "dumb classic switch" + extras so if their fw crash from the physical buttons (not the one on the devices, but their normally open contacts) they still operate. For the car charger I'm obliged to go wifi (I find exactly no one domestic charging station with wired connections for control) but it's a dedicated WLAN (a small GL.iNet "stamp" size on the back of the charger, wired to a dedicated port of my homeserver on a completely separated LAN without internet access and the charger itself is MQTT/ModBUS-bridged to its local, internet-less controller/server for p.v. integration. I can't do nothing for my car and well... Sometimes it's "app-service" to remote control A/C etc get connected to someone else car in another country and yes, I can monitor it and act on it when this happen (few times per years so far). No special hacking needed. No response from the vendor (MG/SAIC)... And for cars some demoed serious remote vulnerabilities able to physically make a car crash while running. All those might be very rare events, but their seriousness it's relevant enough for me to avoid them as much as possible.
daghamm 2y ago
OP is heavily downvoted, but yes some ECU are moving to wireless communication although not WiFi. It started with places where you simply can't have wires, for example tire pressure monitoring. But is now spreading to other simple ECUs. And yes, it can be jammed so obviously it's not for brakes and steering and things like that.
- Gibbon1 2y ago
  You can image the drivers side door has a module that senses the door switches and operates the drivers window and door locks. And communicates via RF to modules in the other three doors to control the windows and door locks. Seriously why the heck not? I've thought in the past what I want for trailer lights is a RF connection between the vehicle and the trailer. It can't be worse than the standard way that always fails.
janice1999 2y ago
It's a good question. Wireless is already replacing wiring inside the battery pack performing some of the most sensitive data transmission. See here for details: https://www.gm-trucks.com/explained-general-motors-wireless-ultium-battery-management/ https://www.gm-trucks.com/explained-general-motors-wireless-...
PlunderBunny 2y ago
If my experience of trying to tether my laptop to my phone on a moving bus is any indication, I'm thinking that WiFi (as opposed to other wireless technologies) is a non-starter.

gorgoiler 2y ago

The before/after ECU layout diagram is very instructional. I like to imagine some kind of engineering “meet cute” whereby, one random day, the headlights engineer and the parking radar engineer happen to be working on the front of the car together. Their eyes meet: “hey, I’m John — I didn’t know you had an ECU here!”, “hi, I’m Claire — wow, you have an ECU right up front too? It’s, like, right next to mine and we never knew!” “I know, crazy right?! Hey this is going to sound really forward and I don’t normally do this but I’m only running at 70% compute capacity. I don’t suppose you need any real-time budget this evening?” “So funny you should ask, I was just about to run a whole bunch of heavy new wiring to…” And in a story as old as time they get ECU married and raise their control loops in the same front-of-vehicle ECU together instead of living their separate, lonely, ECU-right-next-to-each-other-and-they-didn’t-know-it lives.

jdiez17 2y ago
I ... am a bit speechless ... I didn't know this was something I could be into so much, and yet here we are.
- brundolf 2y ago
  That's what they said
kevin_thibedeau 2y ago
Ford did this with the cost reduced version of SYNC 3, merging two modules to form SYNC 2.5. The result is an unstable heap of trash.
- dangus 2y ago
  Well, it is Ford. You buy a Ford you should expect it to be trash.
plg94 2y ago
wow, you made hackernews turn into tumblr. Well done, great explanation.

gregmac 2y ago

It's interesting to think about the failure modes here. With domain-based ECUs, a failure means your locks OR windows OR windshield wipers stop working. With zone-based, it could be the entire "west" zone that stops, which means you can't unlock the driver's door, open the windows, adjust the seat, and maybe even the ventilation fans don't work I actually thought a lot of that was already on the CAN bus anyway, but my knowledge of cars stops there so maybe someone can fill in the gaps. Seeing only three "zones" is actually surprising to me. As I was reading I started forming the idea of a single bus cable that went around the car, with I/O modules anywhere there were physical buttons/lights/etc. There would just have to be a cost+weight balance of where it makes sense to stick a small I/O module vs run individual wires back to a bigger module. My assumption is as technology advances it becomes cheaper to have more small I/O modules with very short wire runs to buttons, but it doesn't seem like this is what they're doing. I am also making the assumption this is "dumb I/O", and somewhere there is a "door lock" program that handles all locks/buttons. In the main computer you'd run all the domain programs individually/isolated, but there would still be a single program responsible for each domain, eg: all the locks (eg: considering button presses, fob buttons, door state, moving or not, etc, and act on the locks accordingly). From a pure software point of view, if the east/west/south ECUs are actually doing the logic for their respective parts of the car, that seems like a nightmare to build: the code would end up being all partial and distributed. In the worst case you end up with bizarre bugs like "if you open the passenger door, then open the tailgate, then close the passenger door and press the lock button, the driver's door will lock but the passenger won't until you first unlock then shut everything" (which gets reported as "the locks are unreliable, some will randomly just not work every few days").

edmundsauto 2y ago
Some door locks will trigger the servo every time you hit the heron (older-ish cars) and some have a sensor. Not clear to me if it’s a remote sensor or some sort of smarts in the local mechanism. Given some of the chip shortages of recent year, I’m curious how the teams responsible for those trade offs made the balance.
guai888 2y ago
Standard approach is following ISO 26262 development to deal with risk resulting from failure mode.

indoorcomic 2y ago

I love this. I hope this more manufactures go this route. I've always felt that having ~100 ECUs in a car is complete overkill.

Jtsummers 2y ago
See gregmac's comment, it changes the failure modes and makes what could be isolated subsystem failures larger regional failures. However, components are also becoming much more reliable so this is an engineering tradeoff. Cases can be made in both directions. EDIT: That's not the only tradeoff, but it is a key one.
- metadat 2y ago
  https://news.ycombinator.com/item?id=41207335 https://news.ycombinator.com/item?id=41207335 In the future, please include the actual link. It is 10x more useful.
AlotOfReading 2y ago
I've been a (somewhat successful) advocate of similar approaches at the automakers I've worked for, but it's not as simple as the article makes it sound. Individual components in each "zone" can have different reliability requirements, for example. They also might be produced by different suppliers, or only be present on certain models / trims. Rivian is able to do this because they're taking advantage of modern heterogenous processors and they haven't made the mistake of outsourcing almost all of their software capabilities to tier 1,2,3 suppliers. Legacy OEMs find it much more difficult to adopt, especially once the institutional inertia takes over.
Ekaros 2y ago
Replacing word ECU with micro-controller makes number seem less insane. Okay, PCs are having less and less components. But one might ask why do so many components have any logic at all? We got extremely insanely powerful central CPUs with loads of memory and storage space. So why not just do absolutely everything there? Remove any logic and computing from screens, keyboards, mice, SSDs, HDDs, off load everything from network chips and sounds chips. Just move all of it to CPU?

OptionOfT 2y ago

I think having multiple ECUs over time is a cost savings mechanism. You have a module that you can use in all your models because it works. If Rivian wants to add a new feature that doesn't 'fit' on the AIO ecu, then what? Replace it and re-certify ALL of its functions? A good example is the ABS controller which is usually just a Bosch COTS ECU. You wouldn't even want to implement that for yourself.

daghamm 2y ago

"four categories get their own ECUs: infotainment, autonomy, vehicle access, drive units, and its battery management system." Am I reading this wrong, or are these actually five categories?

masklinn 2y ago
Given the wording of "drive units, and its battery management system" I'd think the BMS is linked to the drive units and under the same ECU. I'd assume the drive units and BMS are tightly integrated, as that's basically the entire high-voltage system and you have to manage the two-ways energy flow between the two (propulsion and braking / regen).
- trainsarebetter 2y ago
  Not really, the FOC software that runs on the inverters is compute heavy and safety critical. It gets its own dedicated controller (they are actually running to cpus in parallel in case one fails) and same with the bms. They talk over can currently in teslas. bms states it’s max charge and discharge current, and everything else listens

aaron695 2y ago

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schobi 2y ago

The diagrams for the new west south and east zones still show a lot of wires going all across the vehicle. This step might be a good first one to reduce the number of ECUs by combining them, but there is still the same cross-car wiring. You still seem to have a single ECU per function, but merged into a few dedicated boxes for example. Next step: Each wire only goes to the nearest box. I'm curious how the Tesla unboxed architecture will eventually play out. I understand that eventually, the ECUs will be split up, so you have some aspect of each ECU in each corner of the vehicle. Part of the "lights" function is in front-left, part of it in the back. Wires only go to the nearest box. A powerful vision, with the potential to further reduce wiring. Complex until you get a distributed brake ECU.

yc-kraln 2y ago

The electrical wiring in cars is Conway's law manifest in copper. For those unfamiliar with Conway's law, I am arguing that how the car companies have organized themselves--and their budgets--ends up being directly reflected in the number of ECUs as well as how they're connected with each other. I imagine that by measuring the amount of excess copper, you´d have a pretty good measure for the overhead involved in the project management from the manufacturers' side. (I previously worked for Daimler)

mensetmanusman 2y ago
Would be funny to have a ‘mm Cu / FTE’ scaling law.
- throwaway48476 2y ago
  Complexity is a function of the number and depth of suppliers.
- westurner 2y ago
  The ohm*meter^3 is the unit of electrical resistance. Electrical resistivity and conductivity: https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity https://en.wikipedia.org/wiki/Electrical_resistivity_and_con... Is there a name for Wh/m or W/m (of Cu or C) of loss? Just % signal loss? "Copper Mining and Vehicle Electrification" (2024) https://www.ief.org/focus/ief-reports/copper-mining-and-vehicle-electrification https://www.ief.org/focus/ief-reports/copper-mining-and-vehi... .. https://news.ycombinator.com/item?id=40542826 https://news.ycombinator.com/item?id=40542826 There's already conductive graphene 3d printing filament (and far less conductive graphene). Looks like 0.8ohm*cm may be the least resistive graphene filament available: https://www.google.com/search?q=graphene+3d+printer+filament+ohm https://www.google.com/search?q=graphene+3d+printer+filament... Are there yet CNT or TWCNT Twisted Carbon Nanotube substitutes for copper wiring?
  - westurner 2y ago
    * far less conductive graphite; another form of carbon FWIU recent developments in graphene semiconductors for example on silicon carbide are undercapitalized. Can industry undo its unsustainable copper dependency by replacing power wires and data cabling with TWCNT cabling?

lofaszvanitt 2y ago

3rd generation: no wires from sensors to detectors.

twoWhlsGud 2y ago
4th generation: wires are back so the car doesn't stop working every time it drives by a source of RF noise...
- lofaszvanitt 2y ago
  We'll see...

xbmcuser 2y ago

I recalled I read something similar before so I searched for it. It was Tesla doing something like this in 2019 https://electrek.co/2019/07/22/tesla-revolutionary-wiring-architecture-robots-model-y/ https://electrek.co/2019/07/22/tesla-revolutionary-wiring-ar... "In order to facilitate the automation of manipulating cables, Tesla has been reducing the length of wiring harnesses in its vehicles. Musk said that Model S has about 3 kilometers of wiring harnesses and Tesla brought it down to 1.5 kilometers in length for the Model 3. But that’s just the beginning. Tesla is working on a whole new wiring architecture for future vehicle platforms and they aim to bring it down to just 100 meters starting with the Model Y."

grecy 2y ago
Tesla have taken it to a whole new level on cyber truck. It is assumed this will continue in their next gen vehicles
- theluketaylor 2y ago
  The legacy car makers have flirted with 48V components for decades but haven't been willing to do the hard work to realize all the benefits it brings. The germans in particular are stuck in limbo. For their PHEV and BEV cars they are shipping 12V for all traditional functions, 48V for advanced functions like active suspension and anti-roll bars, and high voltage systems for the traction motor. Complete mess. It's frustrating to be a Tesla owner. For every great engineering choice they make like going all in on 48V they make a user hostile choice like removing stalks and selling "full self driving" that is downright dangerous.
  - jvanderbot 2y ago
    The single most frustrating thing Tesla did re: Power was not allowing me to plug an appliance in. We lose power somewhat regularly where I live due to storms, and the tesla has 6-10 days of my household power budget sitting in its banks. Just let me plug in a deep freezer and coffee maker, please. INB4 the 12V terminals: They are hard to access, have limited amps, and are a separate crappy battery.

quanto 2y ago

quick math check > 1.6 miles and 44 pounds pure copper density at 9000 kg/m3, wire diameter assumed at 1mm, length at 3000 m (1.8 mi, approx) gives 21 kg, approximately 46 lb. math checks out. > the company claims a 20 percent savings in material costs and 15 percent reduction in its carbon footprint between Gen 1 and Gen 2. surely this is not just due to the reduction of copper. copper is around 10 USD/kg at bulk. now let's see if we can address the copper length number. can 1.6 mi (< 3000 m) of copper be saved from wiring alone? The car dimensions are 2m x 5m. That means, in the worst case, two ECUs placed at opposite ends will need 5m of wire (half of perimeter). There were 17 ECUs originally. Call it n = 20, and if we wire dense (in the graph sense), we get n^2 = 400. So, in the absolute worst case, the densest possible graph would have had 5m x 400 = 2000 m of wire. The claimed wire saving is significantly (but not by an order of magnitude) larger than this. I would say this passes the smell test (albeit barely), but original wiring must have been truly inefficient.

spydum 2y ago
maybe i missed in your estimate, but most circuits need more than one wire?
- hn72774 2y ago
  In a vehicle, the chassis is the negative wire in the circuit.
  - AlotOfReading 2y ago
    The vast majority of automotive buses use differential signaling over multiple conductors for EMI reasons. The only common exception is LIN and maybe SWCAN if we're exceedingly generous with our definition of "common".
- caleblloyd 2y ago
  I didn’t completely follow either but I think the n^2 = 400 worked out to 20 ECUs each with 20 wires

thelastgallon 2y ago

Rivian can switch to 48V for more gains. https://news.ycombinator.com/item?id=38576612 https://news.ycombinator.com/item?id=38576612: The move to 48V means much less power is lost (power loss = (IxI)xR ), cables can be much smaller, cables and terminals can be much lighter and much less copper can be used used. Discussion: Tesla shares 48V architecture with other automakers: https://news.ycombinator.com/item?id=38557203 https://news.ycombinator.com/item?id=38557203

jondwillis 2y ago
Those are rookie numbers. Let’s bump it up to 96V while we are at it.
- throwaway48476 2y ago
  50V is the generally accepted safe cutoff. There are separate electrical certifications for 'low voltage' <50V.
  - addaon 2y ago
    SELV is often capped at 60 V, not 50 V, although this is often treated as “48 V with crappy bounds”. An example that takes advantage of this would be PoE, which allows 44 V - 57 V at the PSE; but most PSEs are, in my experience, in the 54 - 57 V range.
    - yencabulator 2y ago
      48 V + charging ends up around 54-58 V, so the 60 V cap is needed for 48 V systems.
      - addaon 2y ago
        Only for 48 V systems that have a battery, which does not apply to PoE, and does not apply universally to 48 V automotive approaches (although the CyberTruck does use a 48 V battery).

_heimdall 2y ago

I was expecting to see a mention of whether there were any safety concerns related to running fewer ECUs. I'd assume not since they chose to go this route, but the idea of the infotainment system going down and taking other systems offline with it seems like a risk they would have had to consider.

therealdkz 2y ago

There is nothing like perf improvement that removes sleep() put in earlier…