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.