I was already in motion. Here is a photo of the area where it happened...
Good day fellow Montrealer
Avoiding and braking is all I heard about. What if flooring the gas, going above the speed limit which you may be already traveling at is the only way to avoid an accident, potentially a fatal one. This has happened to me once at an intersection. Someone really late running a red light hit the rear of my car as I floored it after being mid way through the intersection noticing him coming toward me above full speed. If I kept my speed or braked, his car would have hit my door dead on killing me instead of hitting my rear bumper spinning my car around.
What would have an auto-driver done in this situation.
Brake, I'm dead or in the hospital.
Keep the same speed, most likely the same.
Would have the AI chosen to floor the gas here, can the processor and the mechanics of the gaz pedal (not brake pedal) instantly floor it if it needs to? Will it even be programed to accelerate as fast as possible to save the driver, or will braking be the default?
Are you suggesting that the AI wouldn't do the same thing under the strategy of avoidance? It will probably also weigh collateral damage and choose a strategy that results in the least damage to its own car while considering damage to other cars and people.
Anything a human can do, a decent AI can do faster. It's going to take time to develop all the strategies but it will happen.
As stated elsewhere, the acceleration of battery vehicles can be breath taking. My old Spark EV had 400 ft-lbs or torque. That's right up there with muscle cars.
At the moment, driverless cars are just gathering data for the AI to consider. They're mere infants. Give them a few years to mature and things should get really interesting.
Oh, and a decent AI wouldn't let the other car run the red light in the first place. Only ego causes these kinds of accidents and AIs don't have ego.
In this case the hypothetical self-driving car is most probably electric and thanks to the torque characteristics of electric motors can have innate acceleration capacities that far exceed internal combustion engine vehicles. Although in this case there is no foot to be moved, the mechanical actuation time of the braking system will still come into play. Even here it's not impossible that acceleration might yield higher |deltaV|.
Electric motors have maximum torque from rest (0 RPM) which makes them much quicker off the line than an internal combustion engine. That advantage drops off quite rapidly at highway cruise RPM as the IC engine picks up torque vs idle and the electric motor torque drops off with RPM.
Depends on the exact type of electric motor and there are
lots of types, some are even constant torque.
Looking at torque curves for current electric cars, I found none that were constant torque over their operating range. Each had max torque at 0 RPM, steady through a low RPM limit (town/side road driving) and then a declining torque curve with RPM.
There are no doubt electric motors that are torque limited/constant torque over their full operating range. I couldn't find any that made their way into electric cars.
You don't say which jurisdiction you are in, but universally around the world even where bicycle lanes are required to be used they still have exemptions:
I didn't say they are or necessarily should be bound to using bike lanes, but if they're not going to use bike lanes then we should stop wasting money putting them in. If you're going to lobby to spend my tax dollars on an infrastructure project, I expect to see you using the project you begged to have done.
Looking at torque curves for current electric cars, I found none that were constant torque over their operating range. Each had max torque at 0 RPM, steady through a low RPM limit (town/side road driving) and then a declining torque curve with RPM.
There are no doubt electric motors that are torque limited/constant torque over their full operating range. I couldn't find any that made their way into electric cars.
That's a feature of transmissionless BLDC motors, which are the only kind that really makes sense on electric cars. Really the kind of torque curve you get on an ICE is pretty peculiar, with the available power source increasing with crankshaft speed.
You don't say which jurisdiction you are in, but universally around the world even where bicycle lanes are required to be used they still have exemptions:
....
It's a complete waste.
Yes, installing bicycle lanes that aren't suitable for purpose is a complete waste and only increases the tension between road users. But it keeps going on around the world from planners who have never ridden a bicycle on their own designs.
I didn't say they are or necessarily should be bound to using bike lanes, but if they're not going to use bike lanes then we should stop wasting money putting them in. If you're going to lobby to spend my tax dollars on an infrastructure project, I expect to see you using the project you begged to have done.
You'll probably find the cyclists not using the bike lane, didn't want it (in that form or at all) either. But again this doesnt match your narrative.
Does your car accelerate faster than it brakes? Almost certainly not, so you could have moved a bigger delta position at impact by braking than by accelerating
Yes, but what about the car/driver system? You have to add the time taken to remove the foot from the accelerator, move it across to the brake and depress it. Compare with the time required to merely further depress the accelerator.
When you consider the car/driver system rather than just the capabilities of the car, I suspect you might find that accelerating, when already travelling forward with the accelerator partially depressed, creates a higher |delta V|.
Seems its selective quoting day. Cars are optimised for stopping, some hypothetical future high performance electric car might reverse that but it would be incredibly dangerous to unleash on the public. Even the tesla S brakes faster than accelerating:
Cars are optimised for stopping, some hypothetical future high performance electric car might reverse that but it would be incredibly dangerous to unleash on the public. Even the tesla S brakes faster than accelerating:
As would always be expected for a vehicle with both regenerative braking and disc brakes. If friction brakes are required for safety reasons, braking power will always be greater than accelerating power, which must rely on the electric motor force alone.
However, that doesn't mean that braking is better than accelerating for avoiding
every accident. In addition to simple rigid-body mechanics, there is also the issue of control. Standing on the brakes significantly reduces the degree of control you have over the vehicle's direction for dynamic stability reasons.
When the gates close around you at a RR grade crossing, do you really think you are safer slamming on the brakes than on the accelerator?
Cars are optimised for stopping, some hypothetical future high performance electric car might reverse that but it would be incredibly dangerous to unleash on the public. Even the tesla S brakes faster than accelerating:
As would always be expected for a vehicle with both regenerative braking and disc brakes. If friction brakes are required for safety reasons, braking power will always be greater than accelerating power, which must rely on the electric motor force alone.
However, that doesn't mean that braking is better than accelerating for avoiding every accident. In addition to simple rigid-body mechanics, there is also the issue of control. Standing on the brakes significantly reduces the degree of control you have over the vehicle's direction for dynamic stability reasons.
When the gates close around you at a RR grade crossing, do you really think you are safer slamming on the brakes than on the accelerator?
Have you driven cars beyond their limits? A typical car has much more control under loss of traction when braking compared to loss of traction when under power, its just how they're designed. I'm lucky enough to have driven a variety of cars in a variety of situations.
There will be occasions where accelerating is the better choice, but its overblown for its applications to safety. For the railroad crossing example you can easily leave the area before the train arrives without speeding or accelerating, unless you are foolish enough to enter when you can't exit. As above a automated car will be able to make better decisions about the best choice in each particular situation than a human could. Speed limiters, automated braking, autonomy, etc will certainly decrease the overall road toll and accident rate and yes they might introduce a very small number of previously avoidable accidents but I'm yet to see any analysis which shows they'd be a worse choice than not including them.
Does your car accelerate faster than it brakes? Almost certainly not, so you could have moved a bigger delta position at impact by braking than by accelerating
Yes, but what about the car/driver system? You have to add the time taken to remove the foot from the accelerator, move it across to the brake and depress it. Compare with the time required to merely further depress the accelerator.
When you consider the car/driver system rather than just the capabilities of the car, I suspect you might find that accelerating, when already travelling forward with the accelerator partially depressed, creates a higher |delta V|.
Seems its selective quoting day. Cars are optimised for stopping, some hypothetical future high performance electric car might reverse that but it would be incredibly dangerous to unleash on the public. Even the tesla S brakes faster than accelerating:
You miss the point. Yes, with the exception of ridiculous examples like drag cars, all cars brake better than they accelerate. It's not the car that needs to be considered in isolation, it's the complete car/driver system. It doesn't matter how good the car is at stopping until the driver has commanded it to stop.
The case in point is one where the car was in steady motion, with the drivers foot already depressing the accelerator. That foot takes time to move and we were talking about avoiding an accident in a few hundred millisecond time frame. It will take longer to move that foot off the accelerator and onto the brake than it will to just depress the accelerator further; my guess is at least 200 ms. s = ut + at
2 does the rest.
I don't know which will be truly more effective in the scenario BrianHG described, accelerating or braking; none of us do without some controlled experiments. But appealing to the capabilities of the car alone and not considering the complete car/driver system is definitely not going to get to the correct answer.
Have you driven cars beyond their limits? A typical car has much more control under loss of traction when braking compared to loss of traction when under power, its just how they're designed. I'm lucky enough to have driven a variety of cars in a variety of situations.
Eh? Loss of traction implies loss of control, period. That's essentially Newton's first law.
Ask any motorcyclist. Car drivers will believe all sorts of strange things because a car can slide all over the place and generally stay upright. Motorcyclists, on the other hand, firmly believe in Newtonian Mechanics, some times firmly enough that 'ouch' doesn't do it credit.
Have you driven cars beyond their limits? A typical car has much more control under loss of traction when braking compared to loss of traction when under power, its just how they're designed. I'm lucky enough to have driven a variety of cars in a variety of situations.
Eh? Loss of traction implies loss of control, period. That's essentially Newton's first law.
Exceeding traction limits under braking is generally a straight-line affair, leaving the car oriented in the travel direction, more easily recovered, and in the event of an impact, oriented as to best absorb the energy and protect the occupants.
This is not a simple "All loss of traction events are equal because of Newton" case.
Eh? Loss of traction implies loss of control, period. That's essentially Newton's first law.
Not at all, though I have heard this stated as though it were a "fact" by persons with a vested interest in being able to (legally) define someone as being "in control" vs "not in control" of a vehicle. If you're in any doubt about the difference, watch Russ Swift do one of his parallel parking demonstrations, and consider at what specific times you think he's not in control of his car.
Ask any motorcyclist.
Motorcyclist here. It's not a valid comparison.
Have you driven cars beyond their limits? A typical car has much more control under loss of traction when braking compared to loss of traction when under power, its just how they're designed. I'm lucky enough to have driven a variety of cars in a variety of situations.
Eh? Loss of traction implies loss of control, period. That's essentially Newton's first law.
Exceeding traction limits under braking is generally a straight-line affair, leaving the car oriented in the travel direction, more easily recovered, and in the event of an impact, oriented as to best absorb the energy and protect the occupants.
And in what way are you 'in control' if the car is sliding in a straight line forward with no traction? Can you decide to take a control action such as turn, stop and expect it to be effective?
This is not a simple "All loss of traction events are equal because of Newton" case.
What you have in direct quotes there is not something I said. Please do not put words into my mouth.
Eh? Loss of traction implies loss of control, period. That's essentially Newton's first law.
Not at all, though I have heard this stated as though it were a "fact" by persons with a vested interest in being able to (legally) define someone as being "in control" vs "not in control" of a vehicle. If you're in any doubt about the difference, watch Russ Swift do one of his parallel parking demonstrations, and consider at what specific times you think he's not in control of his car.
The first point you're making I suspect alludes to wheelies and standies, both involve rolling rubber on the road, not loss of traction, the rider can apply controlled forces to the road (turning, braking, acceleration), so by my definition qualify as 'in control'.
As to Russ Swift, to be pedantic, was in control, is now in the grip of physics.
Let's not get sidetracked too far here or we're going to end up in the 'general motoring opinions' thread
Ask any motorcyclist.
Motorcyclist here. It's not a valid comparison.
Ex London dispatch rider here and one time (briefly) user of an ACU licence, I'd disagree.
What you have in direct quotes there is not something I said. Please do not put words into my mouth.
I never said that you said that, nor have I altered your quotes. Please do not accuse me of things that I've not done.
The first point you're making I suspect alludes to wheelies and standies
I was thinking of the case where, in a car, the force between the road surface and the tyre is less than the friction limit given by (mu * r).
Consider, for example, how a rally car is driven along a track with a loose surface; it may spend the majority of its time in a condition where it has "lost traction", ie. there is relative motion between the road surface and the lowest point of the wheel. To assert that the driver is not in control, though, is plainly untrue.
What you have in direct quotes there is not something I said. Please do not put words into my mouth.
I never said that you said that, nor have I altered your quotes. Please do not accuse me of things that I've not done.
You used double quotation marks, in standard English usage that implies a direct quote. If that is not what you intended, please use single quotation marks.
The first point you're making I suspect alludes to wheelies and standies
I was thinking of the case where, in a car, the force between the road surface and the tyre is less than the friction limit given by (mu * r).
Consider, for example, how a rally car is driven along a track with a loose surface; it may spend the majority of its time in a condition where it has "lost traction", ie. there is relative motion between the road surface and the lowest point of the wheel. To assert that the driver is not in control, though, is plainly untrue.
Has it 'lost traction' or is it experiencing 'reduced traction'? If it has 'lost traction' inertia applies and control inputs will have no effect. If it has 'reduced traction' then control input will have a reduced effect. In the former no amount of compensation will allow for effective control, in the latter control is possible by compensating for the
reduced traction.
Perhaps others aren't taking such an absolutist view of the phase 'lost traction' as I am ("lost" = ?past perfect? = 'it has been lost'). If you think 'lost traction' includes 'reduced traction' or 'losing traction' ("losing" = ?present continuous? = 'it is being lost') then we're probably arguing at cross purposes.
[Errors of grammatical type naming are all my own, never could remember which was which; so much for a grammar school education, but at least it taught me where to use a semicolon.]
I have to make it clear that I'm most definitely talking about the physics of 'in control'. We're talking about autonomous vehicles and thereby control systems. So we're talking about when systems are 'controlled' (by a control loop, AI or driver) and 'uncontrolled' (the system is in the grip of inertia and external forces).
Your mention of 'legally' in control which reminded me of some prosecutions over wheelies and standies back in the day (mid eighties or nineties I think). You seem to be implying there have been cases around 'in control' and deliberate drifting? Frankly anybody who indulges in deliberate four wheel drifts on the public roads outside of a formal rally deserves to get prosecuted no matter how in control they are or are not in physical fact.
Can we get back to the actual case in point now, accident avoidance by autonomous vehicles (with a side helping of accident avoidance by humans). I'm conscious of having side-tracked this thread too far. I'm not going to indulge in any more commenting on this side issue.
Does your car accelerate faster than it brakes? Almost certainly not, so you could have moved a bigger delta position at impact by braking than by accelerating
Yes, but what about the car/driver system? You have to add the time taken to remove the foot from the accelerator, move it across to the brake and depress it. Compare with the time required to merely further depress the accelerator.
When you consider the car/driver system rather than just the capabilities of the car, I suspect you might find that accelerating, when already travelling forward with the accelerator partially depressed, creates a higher |delta V|.
Seems its selective quoting day. Cars are optimised for stopping, some hypothetical future high performance electric car might reverse that but it would be incredibly dangerous to unleash on the public. Even the tesla S brakes faster than accelerating:
You miss the point. Yes, with the exception of ridiculous examples like drag cars, all cars brake better than they accelerate. It's not the car that needs to be considered in isolation, it's the complete car/driver system. It doesn't matter how good the car is at stopping until the driver has commanded it to stop.
The case in point is one where the car was in steady motion, with the drivers foot already depressing the accelerator. That foot takes time to move and we were talking about avoiding an accident in a few hundred millisecond time frame. It will take longer to move that foot off the accelerator and onto the brake than it will to just depress the accelerator further; my guess is at least 200 ms. s = ut + at2 does the rest.
I don't know which will be truly more effective in the scenario BrianHG described, accelerating or braking; none of us do without some controlled experiments. But appealing to the capabilities of the car alone and not considering the complete car/driver system is definitely not going to get to the correct answer.
You're compressing time down to unrealistic sizes, BrianHG showed an intersection and estimated speeds of 70km/h and 30km/h.
Avoiding and braking is all I heard about. What if flooring the gas, going above the speed limit which you may be already traveling at is the only way to avoid an accident, potentially a fatal one. This has happened to me once at an intersection. Someone really late running a red light hit the rear of my car as I floored it after being mid way through the intersection noticing him coming toward me above full speed. If I kept my speed or braked, his car would have hit my door dead on killing me instead of hitting my rear bumper spinning my car around.
What would have an auto-driver done in this situation.
Brake, I'm dead or in the hospital.
Keep the same speed, most likely the same.
Would have the AI chosen to floor the gas here, can the processor and the mechanics of the gaz pedal (not brake pedal) instantly floor it if it needs to? Will it even be programed to accelerate as fast as possible to save the driver, or will braking be the default?
Does your car accelerate faster than it brakes? Almost certainly not, so you could have moved a bigger delta position at impact by braking than by accelerating, or added some steering input too and changed from a t-bone type collision to a side-to-side vectoring the energy away from the vehicles. There are occasions where a collision to the rear panel could be a better outcome but the usual anecdotes about speeding being necessary for safety are clearly outliers, if the other driver had some level of autonomous driving assistance they wouldn't have run the red light and there would never have been any issue.
I was already in motion. Here is a photo of the area where it happened...
Agreed that if the other drive didn't have driver assistance, but was forcefully always automatic driving, then he would have never run the light in the first place and there would have been no accident. But since he chose to speed through the intersection, I got screwed. Note that he was traveling around 70km/h also where the speed limit was only 50km/h.
Which if you look at the specific intersection in question puts 40m of visibility from the car entering from the left to the point of possible collision, at a steady 70km/h thats 2 seconds to recognise the threat and take action so situational awareness and braking is far and away the safest option. Safe cars need to be predictable, slow acceleration and fast stopping is the direction to head in.
Your mention of 'legally' in control which reminded me of some prosecutions over wheelies and standies back in the day (mid eighties or nineties I think). You seem to be implying there have been cases around 'in control' and deliberate drifting? Frankly anybody who indulges in deliberate four wheel drifts on the public roads outside of a formal rally deserves to get prosecuted no matter how in control they are or are not in physical fact.
I've drifted cars with both front and rear wheel drive for fun and pleasure, then when you have an idiot pull out in front of you on the highway and you get sideways while dumping on the brakes it all comes naturally and the car remains under control (ABS is a wondrous thing) despite being very much beyond the limits of adhesion. Just because the tires can only put 0.8g or so against the road simply limits you to that 0.8g of control, even if you'd like more and are sliding along with the full 0.8g in use.
P.S. it is currently an offence in my state to lose traction on any wheel of a vehicle:
http://www.austlii.edu.au/au/legis/vic/consol_act/rsa1986125/s65a.htmlBut that doesn't stop people spinning their wheels pulling away at traffic lights because its never enforced.
Fully autonomous cars are a pipe dream until we have human level AI. Blocking all traffic on an edge case is not acceptable, yet inevitable without a human to take over.
I've spent a large part of my career working in primarily software companies and one thing that never changes is that no matter how well you test it in house, customers inevitably find all kinds of bugs as soon as it goes out into the field. People do unexpected things, a software developer simply cannot predict everything that real users will do. I'm quite confident that the same thing will happen with these cars, they will get hastily released into the field and within a short time all hell will break loose as all kinds of crazy things happen once ordinary people try using them instead of engineers with thousands of hours working with them and intimate understanding of the technology. It will get much worse if any of these contraptions last long enough that parts start to wear out, sensors get clogged up with road grime, faulty connections develop from wet or salty climates, damage accumulates from minor accidents, etc.