4 ms·

The problem is the disconnect between control input and reaction, and that is far from being a non-issue.

by hef19898 3y ago

ajross 3y ago
No, "the problem" as described is control lag, and decoupled input simply is not the same thing. What you describe as "far from a non-issue" is a characteristic shared by literally every fly/drive-by-wire system. If you trust your Airbus to get you to your destination, you can trust a Cybertruck[1] to get you home. Or if you don't, you need to come to the debate with evidence and not misleading garbage tweets like this one. [1] Or others. Tesla is not the first company to offer steer-by-wire, just the first to engender this kind of nonsense debate about every decision they make.
- Animats 3y ago
  Yes, it's control lag. Our 2005 DARPA Grand Challenge vehicle, a Polaris Ranger ATV, looked like that in manual mode. The steering wheel was drive by wire, and used a simple PI controller. Stationary, with the steering system fighting static friction, the normal P value useful for driving is too low, so there's lag. The I term cranks up the force until the error goes to 0, but that takes time. Our remote dashboard had two pointers on the steering meter - commanded steering angle and actual steering angle. We could watch the lag. Half a second of lag was OK, because we didn't do any aggressive maneuvers. Manual mode was just for positioning the vehicle before going autonomous. That slowdown at the end of the Tesla video looks like normal operation of a PI controller. Does Tesla have steering force feedback? If the steering wheel is leading the wheels, the steering wheel should be pushing back on the driver if there's significant error.
eightysixfour 3y ago
I think the cybertruck is a piece of garbage but people like to say things like this authoritatively on the internet and it is wrong. I like cars, I have built and raced cars. I have owned sports cars, boring hybrids, and a Tesla. I have tuned ECUs and adjust BCMs… cars do not behave as linearly and directly as a lot of Internet engineers seem to think they do. If you watch closely in this video, the steering wheel turning and the wheel starting to turn happen almost instantaneously, there is no initial input lag. The lag is between the steering wheel and wheel reaching center, and that’s dictated by an intentional acceleration curve. This is what I would have expected in a steer-by-wire system. There are things worth complaining about with steer-by-wire and I don’t think this is one of them.
- hef19898 3y ago
  I am extremely picky about those things, it would drive crazy. My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy. I prefer slow, but immediate acceleration. Cool car background by the way! I just wonder why using steer-by-wire, what's wrong with modern power steering?
  - eightysixfour 3y ago
    > My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy. There could be a number of reasons for this but no modern car has a direct connection between the pedal and the throttle bodies, so it isn’t inherent to drive-by-wire. It can probably be tuned out of the S3 in software pretty easily. I haven’t driven one so I won’t claim there is no lag in the Cybertruck’s steering, but I find it pretty unlikely there is observable lag in the initial response compared to other vehicles in its weight class, which aren’t particularly responsive. The three reasons I think are most relevant to Tesla: 1. Packaging - removing the steering column is a pretty dramatic reduction in the number of parts in the front of the car and makes it possible to reuse that space. It may make it easier to design the front crumple zone as well. 2. Extreme variable steering ratios - you can tune the steering ratios much further with a fully by-wire system. In a large vehicle it makes it easier to maneuver at low and high speeds with less effort for the driver. 3. If autopilot were ever to come to fruition, the steering wheel won’t have to move while autopilot turns the car.
    - hef19898 3y ago
      Especially three seems hihhly risky: if the driver has to take over, he has no clue of where the wheels are pointing at. But since FSD wont matetialize for at least another decade, it is not that pressing. Regarding the S3, and Audi's in general, I know that I am one of the few people I know who is really annoyed by that.

The problem is the disconnect between control input and reaction, and that is far from being a non-issue.

No, "the problem" as described is control lag, and decoupled input simply is not the same thing. What you describe as "far from a non-issue" is a characteristic shared by literally every fly/drive-by-wire system. If you trust your Airbus to get you to your destination, you can trust a Cybertruck[1] to get you home. Or if you don't, you need to come to the debate with evidence and not misleading garbage tweets like this one. [1] Or others. Tesla is not the first company to offer steer-by-wire, just the first to engender this kind of nonsense debate about every decision they make.

Animats 3y ago
Yes, it's control lag. Our 2005 DARPA Grand Challenge vehicle, a Polaris Ranger ATV, looked like that in manual mode. The steering wheel was drive by wire, and used a simple PI controller. Stationary, with the steering system fighting static friction, the normal P value useful for driving is too low, so there's lag. The I term cranks up the force until the error goes to 0, but that takes time. Our remote dashboard had two pointers on the steering meter - commanded steering angle and actual steering angle. We could watch the lag. Half a second of lag was OK, because we didn't do any aggressive maneuvers. Manual mode was just for positioning the vehicle before going autonomous. That slowdown at the end of the Tesla video looks like normal operation of a PI controller. Does Tesla have steering force feedback? If the steering wheel is leading the wheels, the steering wheel should be pushing back on the driver if there's significant error.

eightysixfour 3y ago

I think the cybertruck is a piece of garbage but people like to say things like this authoritatively on the internet and it is wrong. I like cars, I have built and raced cars. I have owned sports cars, boring hybrids, and a Tesla. I have tuned ECUs and adjust BCMs… cars do not behave as linearly and directly as a lot of Internet engineers seem to think they do. If you watch closely in this video, the steering wheel turning and the wheel starting to turn happen almost instantaneously, there is no initial input lag. The lag is between the steering wheel and wheel reaching center, and that’s dictated by an intentional acceleration curve. This is what I would have expected in a steer-by-wire system. There are things worth complaining about with steer-by-wire and I don’t think this is one of them.

hef19898 3y ago
I am extremely picky about those things, it would drive crazy. My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy. I prefer slow, but immediate acceleration. Cool car background by the way! I just wonder why using steer-by-wire, what's wrong with modern power steering?
- eightysixfour 3y ago
  > My pet peeve was the Audi S3 I had as rental once, this minuscule, barely recognicable, delay between kicking down the pedal and the car accelerating drove me crazy. There could be a number of reasons for this but no modern car has a direct connection between the pedal and the throttle bodies, so it isn’t inherent to drive-by-wire. It can probably be tuned out of the S3 in software pretty easily. I haven’t driven one so I won’t claim there is no lag in the Cybertruck’s steering, but I find it pretty unlikely there is observable lag in the initial response compared to other vehicles in its weight class, which aren’t particularly responsive. The three reasons I think are most relevant to Tesla: 1. Packaging - removing the steering column is a pretty dramatic reduction in the number of parts in the front of the car and makes it possible to reuse that space. It may make it easier to design the front crumple zone as well. 2. Extreme variable steering ratios - you can tune the steering ratios much further with a fully by-wire system. In a large vehicle it makes it easier to maneuver at low and high speeds with less effort for the driver. 3. If autopilot were ever to come to fruition, the steering wheel won’t have to move while autopilot turns the car.
  - hef19898 3y ago
    Especially three seems hihhly risky: if the driver has to take over, he has no clue of where the wheels are pointing at. But since FSD wont matetialize for at least another decade, it is not that pressing. Regarding the S3, and Audi's in general, I know that I am one of the few people I know who is really annoyed by that.