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posted by martyb on Thursday August 10 2017, @06:04PM   Printer-friendly
from the semileaks dept.

https://arstechnica.com/cars/2017/08/reuters-tesla-looking-to-start-testing-autonomous-semi-in-platoon-formation/

Tesla CEO Elon Musk announced in April that the company is working on pushing a long-haul electric semi truck to market, which is set to be formally revealed in September. Now, Reuters has viewed e-mail correspondence between Tesla and the Nevada Department of Motor Vehicles that indicate that the company has discussed testing semi trucks on the state's roads.

The Reuters report also mentioned that the semis would be outfitted with autonomous functions, so they could traverse the nation's highways without a driver in the front seat. The e-mails seemed to indicate that Tesla's semis would "platoon," that is, drive in a formation such that a number of trucks could follow a lead vehicle. It's unclear whether the lead vehicle would have a driver, or operate autonomously with a person in the front seat to monitor safety.

[...] Reuters also reported that California DMV officials will meet with Tesla this week "to talk about Tesla's efforts with autonomous trucks."


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  • (Score: 2) by fyngyrz on Friday August 11 2017, @01:40PM (1 child)

    by fyngyrz (6567) on Friday August 11 2017, @01:40PM (#552260) Journal

    That's only if you rely on seeing the truck brake before you act, losing precious seconds.

    No. It isn't. At 55 MPH, you're traveling at ~80.6 feet per second. The truck in front hasn't "braked"; the truck in front has collided with another vehicle, perhaps one that crossed the centerline. Or it has fallen into a sinkhole. It went from 55 MPH to a pile of crumpled metal. Something without warning to the leader. If the following truck is instantly informed of the problem by whatever means: communications, sensors, it has (following distance / 80.6) seconds to come to a halt at 55 MPH. If the truck is loaded, as it will surely be for at least half the journey it takes (and all of it if the truck's itinerary is managed well), the stopping distance is significantly extended. Each following truck in the convoy has the same problem based on whatever their following distance is - they have no extra time, because they have no extra warning. If the 2nd truck can't stop in time, neither can any of the others if they are following at the same distance.

    Drafting efficiency has been measured using an automobile (I couldn't find an example with a semi) but let's roll with it: Measured drafting effectiveness for reduction of fuel consumption at 55 MPH is approximately, according to our friends at mythbusters [autoblog.com]:

    100 feet: 32.0 MPG - baseline
     50 feet: 35.5 MPG - 11%
     20 feet: 38.5 MPG - 20%
     10 feet: 44.5 MPG - 27%

    So at 50 feet, for an 11% savings, at 55 MPH (for a car, savings for a truck will likely be considerably less, though following distances will be similar because they are based on getting into the spot behind the leading truck's displacement of the air mass, which doesn't change based on what is following), available stopping distance with instant knowledge of the collision is 50/80.6=.61 seconds. Now ask yourself: Can you imagine a fully load semi coming to a complete halt in about half a second? Again, this assumes zero delays in the information that the following truck needs to come to a complete halt, 55 MPH (likely faster, so less time) and the application of full stopping capability.

    So there's the math. I stand by my earlier assessment. Thump thump thump thump.

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  • (Score: 2) by bob_super on Friday August 11 2017, @04:33PM

    by bob_super (1357) on Friday August 11 2017, @04:33PM (#552404)

    Whoa, lots of typing, yet ignore fundamental physics...
    Step 1: you don't bring 40 tons to a stop instantly, unless you run head-on into a very solid wall (I'm ignoring crumple time to please you). Even when hitting a truck swerving from the oncoming lane, that takes a lot of precision to hit exactly centerline exactly straight. The front truck may slow down faster than the second can handle, but every fraction of a second gained is a chance to avoid a chain reaction.
    Step 2: Why exactly do you assume that something which can stop a truck on a dime somehow cannot be detected a second or two or five before it does? Crunch! You didn't sense a fucking wall, so now your followers are in trouble... A few engineers and test engineers need to be fired!
    Step 3: Getting back to my original statement, I didn't imply it was foolproof, but would work in most cases and wrote that you may get a pileup in extreme circumstances. But your objection is ridiculous, because if we worried about sinkholes and pop-up-insta-truck-stop obstacles on our roads, we would never, ever, get in a vehicle, and probably not even on a horse.

    Also note that trucks being shaped like bricks (in most countries), drafting benefits are higher than you think. A car not drafting has a pretty good Cx.
    See also my other reply to you about the horror of potentially losing multiple payloads.