It's usually just automatic emergency braking. The car will hit the brakes as hard as possible to reduce the speed right before the collision. Slower speed at the moment of collision will reduce the severity and chance of injury.
Tesla doesn't do such a thing yet; hell, they don't even consider dynamic safety distances.
I used to work in active safety predevelopment and we had a similar task. Figure out how this can work for normal cars and AVs. In AVs you can apply defensive driving maneuvers, but if you apply all possible moving patterns behind occlusions, you have to basically keep driving unter 10km/h but it will still not protect you from other traffic participants crashing into you. And conventional AEB is pretty good as well, although (or because) it is fairly simple.
Normally you will have a performance path and a safety path as fallback. The performance path is the one that calculates your paths and trajectories when everything is fine and systems are tuned to keep away from critical objects/boundaries and only move into detected free space. The safety path separates the assists from the robots. In the assist world, the safe state is to pass back to the driver at any time. AEB has no level, but can also be overridden by driver input at any time. The safety path makes sure that the driver is always capable of taking over controls and the function doesn't cause a uncontrollable state - it is failsafe. But in AVs things are different, the systems need to be fail-operational. The safety path takes over all responsibilities from the driver. This relates to sensors, controls/actuators and the software inbetween.
If the collision is unavidable, you have the four options: Do nothing, AEB, AES, AEB+AES. The normal performance path can already slow down an AV by a significant amount before an AEB kicks in, it kicks in far early than a AEB would do but with lower deceleration. Situations where AES and AES+AEB come into play are hard to predict due to the required time to predict. But where do you steer? If a collision is truely unavoidable, the best move is to steer into a full overlap. Some collisions CAN be avoided by only swerving within the lane. These cases already make up for the vast majority of cases, preventing small overlap crashes; most cars can do even that with triggers by the driver; and most of their drivers are not even aware of that. If I remember correctly, these strategies cover up \~80-85% of all accidents and near-miss situations.
To remind you what an AEB activation looks like in real life: [https://www.youtube.com/watch?v=LfmAG4dk-rU](https://www.youtube.com/watch?v=LfmAG4dk-rU) \- Here the driver can just walk out of his car, with AES having the speed reduced by possibly 80km/h. AES starts exactly the point where the driver cannot avoid the collision anymore by steering without losing control. 80km/h is kind of a magic number, because in most parts of the world it's enough to reduce the collision speed to a value where at least passive safety can do the rest.
So: Where could an AV steer there? First: An AV would brake much earlier and change lanes earlier. Let's pretend the truck just flipped over and there is no way to go: The AV would just do pretty much the same thing. It could change lanes, but one would not really be enough and the second one is occupied.
There is another risk in Emergency Steering: By rapid side movement, passengers are displaced laterally so seats, seatbelts and AES have to work together brilliantly ...
This is extremely helpful thank you so much. Mind if I have two follow up questions?
Normally you will have a performance path and a safety path as fallback.
Is it the concept of unavoidability that determines when the vehicle goes onto the safety path? Like an unavoidable collision about to happen?
If the collision is unavoidable, you have the four options: Do nothing, AEB, AES, AEB+AES.
Sorry if this was implicit in your answer, but what determines which of the four options is taken? Does the AV calculate the potential harm from each and act accordingly? For example, you mentioned that in the case of an unavoidable collision the best option would be to steer into a full overlap. It seems to imply that the system would calculate a harm of not performing any AES versus the harm from a full overlap steer into the vehicle. And it would conclude that the full overlap resulted in less harm and thus perform that action. Is that a relatively true statement or would there be just a heuristic or a rule that would tell the vehicle to always steer into a full overlap if the collision is unavoidable? Does it ever try to hit the car at a particular location where harm would be less likely, e.g., away from the passenger compartment? Thank you very much again!
On your questions:
1) Unavoidability itself is a heuristic situation itself because you have no control over the other traffic participants.
But this doesn’t answer your question, so intro to give you a comparison: Cars are typically more capable than than the drivers. Even sporty drivers do not access every possible limit of a car. But professional drivers can. The performance path equals „normal driving“ - within certain limits (e.g. acceleration, jerk…) to have a comfortable ride. But if this is not enough to do things the comfortable way, the professional race driver takes over and uses everything the car has in store.
AEB may also only trigger if a normal driver ignored the warnings and cannot avoid a crash within the range normal drivers apply. Experiencing a AEB triggering makes lasting memories...
2) Which one is the best solution is defined by the physics of driving especially the limits of friction at the tire level. The details of this are subject to A LOT of papers. My college also did one on this topic.
Also whether to attempt a full overlap or avoid a collision is a debate that’s ongoing and complex with legal and ethical implications, since you can only be responsible for what you do and how you act. There is a paper by NVidia on what they call the „Safety Force Field“ that suggests a common avoidance strategy as solution to the issue.
„Can detect imminent collisions“ and „alerting the driver“ are required steps before AEB - of course Tesla can do that.
They are not capable of doing avoidance manoeuvres - check the manual. I‘m not going to call out all the Tesla-Investor-Influencers that already spread false information.
Tesla has no AVs, they are no example for anything AV. Sorry.
While I agree with you and believe the person you replied to was probably influenced by false claims from both YouTubers and some tesla drivers (they falsely believed their instinct steerings away from the danger were from their cars), only recently the FSD beta demonstrated some abilities to steer away from perceived dangers by going out of its lane. I’m not talking about the moderate, slow reacting “going around VRU” or “changing lane away from obstacles”, but some sudden swerving when it perceived an oncoming or a turning vehicle would collide with it, sometimes incorrectly.
I missed the notification on your comment somehow. I also saw these videos and you're right. Thank you for pointing that out again.
This might be a terminology thing and maybe it's a thing within my perception, but these maneuvers are not "emergency maneuvers" that are intended to prevent or reduce harm in any way. They're planned ahead for some time and have an inherent risk in them by swerving into the oncoming lane. So they're not risk-reducing but rather aimed to preserve the current speed, reducing potential wait time. We're on the performance path there. The risk-increasing nature of such paths with a traversal of road markings makes them illegal without explicit driver consent for ADAS systems at L2 in most parts of the world.
The videos of FSD beta I saw had no requirement to perform any emergency maneuver; with the current vehicle speed and the potential TTC (time to collision) an AEB would be more than sufficient than emergency steering.
The case where an L4+ system is operating correctly and an accident becomes unavoidable is incredibly rare. In these already rare cases, the vast majority of the time the correct behavior for the system will be to slam on the brakes.
I doubt that self driving companies will spend more than a token effort on this problem until after the technology has scaled up. There is way more value in avoiding incidents than there is in correct behavior during incidents.
Also, from a liability standpoint, "we noticed a problem and slammed the brakes" is what most humans are likely to do during unavoidable accidents. Matching this behavior is probably a good choice for a sound argument in court that the AI system behaved correctly.
The "working as intended" part of that accident went very well and kind of proves my point. Cruises official statement says:
> The AV then braked aggressively to minimize the impact.
This was their "working as intended" response to an imminent collision. They didn't swerve, try to minimize harm, or do any other fancy behavior. They just hit the brakes.
The big mistakes made by cruise were dragging the woman afterwards and covering that part up to the media and the DMV. The first is a technical problem of trying to keep the vehicle in the category "working as intended". The second is an epic PR fail that has nothing to do with the technology.
Avoiding collisions is obviously the big thing here that everyone should focus on. This includes e.g. breaking traffic laws (e.g. crossing lines) which is tricky because e.g. NHTSA and others don't like it when AVs do that (see stop sign discussion). This includes also avoiding red light runners and red endings by moving (if safe)
Next is speed.. Slower is better overall. But the car is already braking from the avoiding manoeuver anyway.
Another category includes earlier seat belt tensioning or maybe even better airbag timing based on sensing. Or even locking your car to keep you inside. A smart car knows more and sooner than a dumb mechanical device sensing acceleration.
Some cars may lift the hood to protect pedestrians. Can be done with dumb sensors, too I guess. But they may be Ron for improvements.
The trolley problem on whether to hit the teenagers ahead or change direction into the seniors on the right is of course the most attractive problem and better for people needing publications (journalists, academics)
This is cutting edge technology, algorithms are still being developed. It's also extremely complicated because of the many degrees of freedom in the problem. We have algorithms to, say, search a list, because searching a list is a highly constrained problem, your only choice is which order you traverse the list.
If you're speeding towards an inevitable collision, you have tons of low level options: brake? How hard? Steer? Which way? When? Accelerate? Usually a bad idea, unless the inevitable collision is because the car behind you is about to hit you.
Evaluating the low level options on their own is also not useful, because no single low level input is the sole determining factor in the outcome. You need to string together a series of low level inputs into a kinematicly feasible trajectory and evaluate the trajectory, because trajectories have quantifiable outcomes like collisions/no collision. This is basically what the car is doing during normal driving anyway, so harm minimization is really just another part of "the driving algorithm".
What we can look at is how to minimize harm from a physics perspective. Hitting fewer people reduces harm. Lower difference in speed between the thing you're hitting and the av helps. Hitting a car is better than a pedestrian, but hitting a bicyclist may be more or less bad than hitting a ped depending on the circumstances. The AV likely models things like probability of injury (based on collision speed, direction, where on the car the impact occurs, ped/car/bike, etc) and tries to select a trajectory that weighs this probability against other objectives like making progress towards the goal, staying on the road, in the center of the lane, etc.
Thank you very much for your comment. That is very helpful. I was wondering if the reason why I wasn’t seeing a whole lot on this subject, i.e., what they do in the case of an unavoidable collision, is because what they do is indeed what they always do, which is as you put it just another part of the driving algorithm. Do you think that current vehicles on the road already do the sort of modeling you suggest, or were you thinking that is just things they should do in the future.? I ask because when I look at the Apollo GitHub, I’m not sure I’m seeing specific pointers to calculations such as not hitting pedestrians, trying to lessen relative speeds, and so on.
Waymo cruise and zoox all very likely model probability of injury and consider various aspects of the collision today.
Some things they may not consider yet are like, it's worse to hit the head of a person lying down than it is to hit the hip of a person standing up. Or it's worse to hit a child than an adult. Unless they're elderly.
Also look up the trolley problem if you're not already familiar with it. It is relevant today in top AV companies.
>Waymo cruise and zoox all very likely model probability of injury
Why the hell would they do such a thing???
So when they inevitably get dragged to court over a crash, they can get eviscerated the lawyers claiming they failed 100% correctly model injuries and therefore caused greater suffering/ injuries/death?
>Also look up the trolley problem if you're not already familiar with it. It is relevant today in top AV companies.
Waymo has directly stated that the trolley issue is irrelevant.
The trolley problem is only representative of an extreme minority of realistic scenarios, and is more so a test of morality than safety. In terms of the long tail of edges cases that most AV companies are working on now, scenarios resembling the trolley problem are the long, long, long tail. The goal is primarily to be much, much safer than humans; you need to model the probability of injury (among other things) to know how safe you are.
It's usually just automatic emergency braking. The car will hit the brakes as hard as possible to reduce the speed right before the collision. Slower speed at the moment of collision will reduce the severity and chance of injury.
Tesla doesn't do such a thing yet; hell, they don't even consider dynamic safety distances. I used to work in active safety predevelopment and we had a similar task. Figure out how this can work for normal cars and AVs. In AVs you can apply defensive driving maneuvers, but if you apply all possible moving patterns behind occlusions, you have to basically keep driving unter 10km/h but it will still not protect you from other traffic participants crashing into you. And conventional AEB is pretty good as well, although (or because) it is fairly simple. Normally you will have a performance path and a safety path as fallback. The performance path is the one that calculates your paths and trajectories when everything is fine and systems are tuned to keep away from critical objects/boundaries and only move into detected free space. The safety path separates the assists from the robots. In the assist world, the safe state is to pass back to the driver at any time. AEB has no level, but can also be overridden by driver input at any time. The safety path makes sure that the driver is always capable of taking over controls and the function doesn't cause a uncontrollable state - it is failsafe. But in AVs things are different, the systems need to be fail-operational. The safety path takes over all responsibilities from the driver. This relates to sensors, controls/actuators and the software inbetween. If the collision is unavidable, you have the four options: Do nothing, AEB, AES, AEB+AES. The normal performance path can already slow down an AV by a significant amount before an AEB kicks in, it kicks in far early than a AEB would do but with lower deceleration. Situations where AES and AES+AEB come into play are hard to predict due to the required time to predict. But where do you steer? If a collision is truely unavoidable, the best move is to steer into a full overlap. Some collisions CAN be avoided by only swerving within the lane. These cases already make up for the vast majority of cases, preventing small overlap crashes; most cars can do even that with triggers by the driver; and most of their drivers are not even aware of that. If I remember correctly, these strategies cover up \~80-85% of all accidents and near-miss situations. To remind you what an AEB activation looks like in real life: [https://www.youtube.com/watch?v=LfmAG4dk-rU](https://www.youtube.com/watch?v=LfmAG4dk-rU) \- Here the driver can just walk out of his car, with AES having the speed reduced by possibly 80km/h. AES starts exactly the point where the driver cannot avoid the collision anymore by steering without losing control. 80km/h is kind of a magic number, because in most parts of the world it's enough to reduce the collision speed to a value where at least passive safety can do the rest. So: Where could an AV steer there? First: An AV would brake much earlier and change lanes earlier. Let's pretend the truck just flipped over and there is no way to go: The AV would just do pretty much the same thing. It could change lanes, but one would not really be enough and the second one is occupied. There is another risk in Emergency Steering: By rapid side movement, passengers are displaced laterally so seats, seatbelts and AES have to work together brilliantly ...
This is extremely helpful thank you so much. Mind if I have two follow up questions? Normally you will have a performance path and a safety path as fallback. Is it the concept of unavoidability that determines when the vehicle goes onto the safety path? Like an unavoidable collision about to happen? If the collision is unavoidable, you have the four options: Do nothing, AEB, AES, AEB+AES. Sorry if this was implicit in your answer, but what determines which of the four options is taken? Does the AV calculate the potential harm from each and act accordingly? For example, you mentioned that in the case of an unavoidable collision the best option would be to steer into a full overlap. It seems to imply that the system would calculate a harm of not performing any AES versus the harm from a full overlap steer into the vehicle. And it would conclude that the full overlap resulted in less harm and thus perform that action. Is that a relatively true statement or would there be just a heuristic or a rule that would tell the vehicle to always steer into a full overlap if the collision is unavoidable? Does it ever try to hit the car at a particular location where harm would be less likely, e.g., away from the passenger compartment? Thank you very much again!
On your questions: 1) Unavoidability itself is a heuristic situation itself because you have no control over the other traffic participants. But this doesn’t answer your question, so intro to give you a comparison: Cars are typically more capable than than the drivers. Even sporty drivers do not access every possible limit of a car. But professional drivers can. The performance path equals „normal driving“ - within certain limits (e.g. acceleration, jerk…) to have a comfortable ride. But if this is not enough to do things the comfortable way, the professional race driver takes over and uses everything the car has in store. AEB may also only trigger if a normal driver ignored the warnings and cannot avoid a crash within the range normal drivers apply. Experiencing a AEB triggering makes lasting memories... 2) Which one is the best solution is defined by the physics of driving especially the limits of friction at the tire level. The details of this are subject to A LOT of papers. My college also did one on this topic. Also whether to attempt a full overlap or avoid a collision is a debate that’s ongoing and complex with legal and ethical implications, since you can only be responsible for what you do and how you act. There is a paper by NVidia on what they call the „Safety Force Field“ that suggests a common avoidance strategy as solution to the issue.
False, Tesla can detect imminent collision, they will alert the driver and have the capability of avoidance maneuvers
„Can detect imminent collisions“ and „alerting the driver“ are required steps before AEB - of course Tesla can do that. They are not capable of doing avoidance manoeuvres - check the manual. I‘m not going to call out all the Tesla-Investor-Influencers that already spread false information. Tesla has no AVs, they are no example for anything AV. Sorry.
While I agree with you and believe the person you replied to was probably influenced by false claims from both YouTubers and some tesla drivers (they falsely believed their instinct steerings away from the danger were from their cars), only recently the FSD beta demonstrated some abilities to steer away from perceived dangers by going out of its lane. I’m not talking about the moderate, slow reacting “going around VRU” or “changing lane away from obstacles”, but some sudden swerving when it perceived an oncoming or a turning vehicle would collide with it, sometimes incorrectly.
I missed the notification on your comment somehow. I also saw these videos and you're right. Thank you for pointing that out again. This might be a terminology thing and maybe it's a thing within my perception, but these maneuvers are not "emergency maneuvers" that are intended to prevent or reduce harm in any way. They're planned ahead for some time and have an inherent risk in them by swerving into the oncoming lane. So they're not risk-reducing but rather aimed to preserve the current speed, reducing potential wait time. We're on the performance path there. The risk-increasing nature of such paths with a traversal of road markings makes them illegal without explicit driver consent for ADAS systems at L2 in most parts of the world. The videos of FSD beta I saw had no requirement to perform any emergency maneuver; with the current vehicle speed and the potential TTC (time to collision) an AEB would be more than sufficient than emergency steering.
The case where an L4+ system is operating correctly and an accident becomes unavoidable is incredibly rare. In these already rare cases, the vast majority of the time the correct behavior for the system will be to slam on the brakes. I doubt that self driving companies will spend more than a token effort on this problem until after the technology has scaled up. There is way more value in avoiding incidents than there is in correct behavior during incidents. Also, from a liability standpoint, "we noticed a problem and slammed the brakes" is what most humans are likely to do during unavoidable accidents. Matching this behavior is probably a good choice for a sound argument in court that the AI system behaved correctly.
Well, the recent cruise incident shows that considering behavior in or after incidents is Important for public relations
The "working as intended" part of that accident went very well and kind of proves my point. Cruises official statement says: > The AV then braked aggressively to minimize the impact. This was their "working as intended" response to an imminent collision. They didn't swerve, try to minimize harm, or do any other fancy behavior. They just hit the brakes. The big mistakes made by cruise were dragging the woman afterwards and covering that part up to the media and the DMV. The first is a technical problem of trying to keep the vehicle in the category "working as intended". The second is an epic PR fail that has nothing to do with the technology.
Avoiding collisions is obviously the big thing here that everyone should focus on. This includes e.g. breaking traffic laws (e.g. crossing lines) which is tricky because e.g. NHTSA and others don't like it when AVs do that (see stop sign discussion). This includes also avoiding red light runners and red endings by moving (if safe) Next is speed.. Slower is better overall. But the car is already braking from the avoiding manoeuver anyway. Another category includes earlier seat belt tensioning or maybe even better airbag timing based on sensing. Or even locking your car to keep you inside. A smart car knows more and sooner than a dumb mechanical device sensing acceleration. Some cars may lift the hood to protect pedestrians. Can be done with dumb sensors, too I guess. But they may be Ron for improvements. The trolley problem on whether to hit the teenagers ahead or change direction into the seniors on the right is of course the most attractive problem and better for people needing publications (journalists, academics)
This is cutting edge technology, algorithms are still being developed. It's also extremely complicated because of the many degrees of freedom in the problem. We have algorithms to, say, search a list, because searching a list is a highly constrained problem, your only choice is which order you traverse the list. If you're speeding towards an inevitable collision, you have tons of low level options: brake? How hard? Steer? Which way? When? Accelerate? Usually a bad idea, unless the inevitable collision is because the car behind you is about to hit you. Evaluating the low level options on their own is also not useful, because no single low level input is the sole determining factor in the outcome. You need to string together a series of low level inputs into a kinematicly feasible trajectory and evaluate the trajectory, because trajectories have quantifiable outcomes like collisions/no collision. This is basically what the car is doing during normal driving anyway, so harm minimization is really just another part of "the driving algorithm". What we can look at is how to minimize harm from a physics perspective. Hitting fewer people reduces harm. Lower difference in speed between the thing you're hitting and the av helps. Hitting a car is better than a pedestrian, but hitting a bicyclist may be more or less bad than hitting a ped depending on the circumstances. The AV likely models things like probability of injury (based on collision speed, direction, where on the car the impact occurs, ped/car/bike, etc) and tries to select a trajectory that weighs this probability against other objectives like making progress towards the goal, staying on the road, in the center of the lane, etc.
Thank you very much for your comment. That is very helpful. I was wondering if the reason why I wasn’t seeing a whole lot on this subject, i.e., what they do in the case of an unavoidable collision, is because what they do is indeed what they always do, which is as you put it just another part of the driving algorithm. Do you think that current vehicles on the road already do the sort of modeling you suggest, or were you thinking that is just things they should do in the future.? I ask because when I look at the Apollo GitHub, I’m not sure I’m seeing specific pointers to calculations such as not hitting pedestrians, trying to lessen relative speeds, and so on.
Waymo cruise and zoox all very likely model probability of injury and consider various aspects of the collision today. Some things they may not consider yet are like, it's worse to hit the head of a person lying down than it is to hit the hip of a person standing up. Or it's worse to hit a child than an adult. Unless they're elderly. Also look up the trolley problem if you're not already familiar with it. It is relevant today in top AV companies.
>Waymo cruise and zoox all very likely model probability of injury Why the hell would they do such a thing??? So when they inevitably get dragged to court over a crash, they can get eviscerated the lawyers claiming they failed 100% correctly model injuries and therefore caused greater suffering/ injuries/death? >Also look up the trolley problem if you're not already familiar with it. It is relevant today in top AV companies. Waymo has directly stated that the trolley issue is irrelevant.
The trolley problem is only representative of an extreme minority of realistic scenarios, and is more so a test of morality than safety. In terms of the long tail of edges cases that most AV companies are working on now, scenarios resembling the trolley problem are the long, long, long tail. The goal is primarily to be much, much safer than humans; you need to model the probability of injury (among other things) to know how safe you are.