When an Algorithm Takes the Wheel

Wired has an interesting look at Jaguar's new automated driving dynamics system in their new XK convertible. From the article: "During an extreme test of the XK's handling capabilities, the car only fishtailed back and forth once after I jerked the steering wheel on a wet road around a 90 degree turn while driving at about 60 mph. The car's back wheels swung first left then right before the XK's sensors registered a difference in torque between the rear tires and, transparent to me, righted the fishtailing effect by a combination of de-acceleration, tire rotation and vehicle weight distribution control. More often than not, the sensation of flatness, as if there were a vertical force pinning the car to the road, was also felt then and when taking less extreme curves at high speeds."

Comments

Not intrusive at all

[compact_support]

I drive a 1999 Toyota Solara SLE V6. There is a switch beside the transmission to disengage the traction control systems. I absolutely agree with you that their traction control is awful on snow. Getting from my house to the main roads through the residential neighbourhood requires disengaging the traction control and manually shifting the transmission between 1st, 2nd, and automatic. Probably because I'm too cheap to buy snow tires. A 2006 Lexus IS I looked at recently had a 3 way traction control switch: On, Off, and Snow. Apparently, Lexus agrees with us you about their performance on snow. CS

Re:Intrusive.

[smellsofbikes]

Well... the absolute fastest way to stop is to hit the brake and hold it at the point just before the car starts to slide -- because sliding friction is (usually) much less than static friction, you don't want to slide, but you also want as much energy removed from the system per unit time as possible, so you want to hold the car *right* at the edge of the static->sliding transition. The way an ABS works is to modulate the force you're putting on the brake at some very high repetition rate, to approximate this maximum static friction case. So for most people (myself and 99% of all humans, excepting people who have extensive training under race conditions) the ABS approximates the ideal stopping distance but a few people can stop a car faster without ABS than with.

That's a technicality, though. The number of people who can do this probably is in the hundreds, worldwide. (I had a friend who drove Formula 1's professionally and he could only manage to outdo an ABS about 20% of the time when he tried it.) So for real-world conditions, you're right: an ABS approaches an ideal stopping force, and allows you to A: not have great skill while still getting this benefit, and B: try and steer the car without worrying about braking modulation.

I'm glad many cars have it, and I wish all cars had it.

Mine works quite well in snow and mixed snow/ice/mud, even offroad. I'm really impressed by it.

Re:Intrusive.

[Somegeek]

Modern ABS systems will allow you to completly lock the wheels at slow speeds, like below 5mph. This also helps on loose surfaces like gravel.

Re:When algorithms go bad

[superid]

possibly this one
http://catless.ncl.ac.uk/Risks/8.77.html#subj6

Cadillac had it since '97

[up2ng]

I have a 1997 Cadillac DeVille, as part of the Northstar system I have ABS/Traction Control and ICCS (Integrated Chassis Control System) AKA Stabilitrak. My car does what this Jaguar does by keeping the car going where I point the steering wheel, and Cadillac has had it since 1997!
The system does what it is supposed to and does it well, it has saved my ass a couple of times on icy winter roads. My only problem is that if you are a good driver these systems will help you, if you are the type that pushes a car just because a system like this in in place you will get into trouble. The systems work very well but they haven't figured out how to change physics yet, a 3,500lb car will not change direction or stop on a dime.
The old adage "Just because you can doesn't mean you should" definatly applies here, drive these cars in a "spirited" fashion but a left turn on an icy road doing 60 mph is not in your future.

Re:When algorithms go bad

[Rinzai]

Airbus has had a terrible record with their flight control software. What's worse, it's nearly impossible to turn off. On the aircraft in the video (referenced elsewhere the thread), the flight control software decided that the plane should be landing, so it kicked into landing mode. The pilots were trying to throttle up and pull back the yoke, but the software had a built-in timer requiring at least 11 seconds of attempted counter-commands before it allowed the override. That was enough to put the plane in the trees.

A former manager of mine mentioned a case with an A300 in Europe that wouldn't go below 6000ft because the computer decided that it just wasn't going to. Finally the flight engineer, in contact with Airbus folks on the ground, ended up under the panels pulling out modules until the auto-pilot was singing "Bicycle built for two," and they managed to get the thing onto the ground in Bonn in one piece.

Most professional pilots in the USA can't stand the Airbus planes for that reason; on the Boeings, you just slap down a couple of paddles and you're in control. (I wrote flight performance computer simulations for desk-top flight trainers for a few years. I heard some stories.)

Re:Intrusive.

[Anonymous Coward]

One thing that has always worried me about anti-lock brakes, is what happens when I really need to lock everything up - like when I am sliding out of control in a safe direction and need to make sure the car does not spear off. I've been there on snow and - ahem - in other circumstances.

Let me get this right, you are sliding out of control in a so-called safe direction and want to lock the wheels? Why? Locking the wheels will not stop the car any faster than a decent ABS. With the wheels locked you will lose the minimal steering control you have.

And you are allegedly travelling in a "safe" direction, so you don't need to stop. If you want to continue sliding, just do nothing. The car will continue to slide.

Me, I prefer the ABS. I took the BMW driver course a few years back, and we had buttons in the cars to disable the ABS and traction control. There was an enormous difference in stopping distance and control on wet & dry road. ABS lets you apply the maximum possible braking force for your tires and that road surface. If you're driving on wet ice, the maximum possible braking force isn't very big (so you should still drive very slowly, even with snow tires & ABS), but ABS is still far better.

A possible problem I would be worried about with this new system is that when the back end finally does break away, its going to go so fast you have no chance of correcting.

If the dumbass is turns sharply at a speed high enough to overcome traction control, the dumbass deserves what he gets. Without traction control the dumbass would have wiped out long before.

Dangerously incorrect

[Dire Bonobo]

> a locked tire will slow you down faster than ABS in many circumstances.

Not only wrong, but dangerously wrong. This is the kind of incorrect belief that can get people killed.

For car tires, static friction (i.e., when the tire is rolling) is almost always significantly higher than dynamic friction (i.e., when the tire is skidding). In other words, skidding tires brake slower than rolling tires.

ABS makes your car more controllable; it also makes your car stop faster. This is, in almost all situations, not a tradeoff---ABS is simply flat-out better than non-ABS in all meaningful ways.

Re:Intrusive.

[smellsofbikes]

One of my favorite authors, Malcolm Gladwell, wrote about SUV's and driver safety concentrating on comparing accident evasion (by steering) in a Porsche and an Explorer. It's worth reading.

One plus of ABS is that, in the hands of an unskilled driver, it allows significant evasion capability that a standard car might/would not allow because side-loading combined with heavy braking would exceed the tire's roadholding. As such it becomes a significant safety aid for the vast majority of drivers.

Limits will always be tested

[CptPicard]

One more technology that allows people to drive even more carelessly and dangerously, blindly relying on automation to keep the car under control. Physics will always remain the same, and I suspect that when the driver DOES lose control of the vehicle, the outcome is going to be all the worse for this.

Not to mention what happens when inexperienced drivers learn to drive with this stuff and then move to a vehicle without it. For example I have never driven a car without ABS and I suspect I need to kept well away from them, as I don't have the correct reflexes to prevent wheels from locking in an emergency.

There was once this British driving instructor who said that all cars should have a long, sharp spike protruding from the center of the steering wheel... it would be the best imaginable safety equipment.

Re:Intrusive.

[mph]

Maybe this had nothing to do with the fact that the vehicle had ABS

Or maybe it had everything to do with ABS. See page 34 of this report by the NHTSA. It reads:

On loose gravel, each of the nine vehicles stopped in the shortest distance with a panic brake application and disabled ABS, regardless of the loading condition. Stops made on the gravel were lengthened considerably when ABS was active: 24.6% when the test vehicles were fully laden and 30.0% when lightly laden.

It is generally accepted that the plowing of a vehicle's tires into a deformable surface such as loose gravel generates greater stopping forces than if the wheels were allowed to continue to roll over the surface (as in an ABS-assisted stop).

Re:Washington State Drivers

[damiam]

ABS doesn't slow you down any better then non-ABS systems

Yes and no. The fastest way to stop any car is to brake at the limit of traction - so that the wheels are still rolling, but any more braking and they'd lock up. A skilled driver can do that in a non-ABS car, but most people can't - they just slam on the brakes and lock the wheels, causing a skid. ABS will make a normal driver stop faster by preventing that skid and braking at the limit of traction.

What it DOES do though is allow you to steer while under maximum breaking conditions.

Not quite. You can never steer under maximum braking conditions, because your tires only have limited traction and, if you're truly braking at the limit, there's no more traction left for turning. No ABS system can overcome that, it's just physics. What ABS does is let off the brakes slightly when you turn the wheel, so that you're no longer under maximum braking. This frees up traction for steering. A good driver would do the same thing, but most people don't have the presence of mind to let off the brakes in a skid, so ABS comes in quite handy.

Re:When algorithms go bad

[Anonymous Coward]

Your lies are somewhat amusing:

A former manager of mine mentioned a case with an A300 in Europe that wouldn't go below 6000ft because the computer decided that it just wasn't going to. Finally the flight engineer, in contact with...

The revolutionary thing when the A300 was launched was that a flight engineer was no longer needed and it could thus be flown by a crew of two. Somebody else has apparently already debunked the rest of your bullshit.