Lane Keeping Assist

We have just replaced our 15 year old VW Touran diesel with a T-Cross 1.0 TSi. This is, as all new cars, fitted with lane keeping assist. I was wondering what would happen if it got confused? Could I, or my wife, fight it and win. Looking at the Bosch variant it either uses the electric power steering, if fitted, or brakes individual wheels using the ESP.

https://www.bosch-mobility.com/en/solutions/assistance-systems/lane-keeping-assist/

“Lane keeping assist uses a video camera to detect the lane markings ahead of the vehicle and to monitor the vehicle's position in its lane. If the vehicle’s distance to the lane markings falls below a defined minimum, the system steps in. In vehicles with electric power steering, it gently, but noticeably countersteers in order to keep the vehicle in the lane. In vehicles without electric power steering, it achieves the same effect by utilizing the electronic stability program (ESP®) to brake individual wheels.

Drivers can override the function at all times, so they retain control of the vehicle. If they activate the turn signal in order to intentionally change lanes or turn, the system does not intervene.”

I am fairly happy with these various assist systems so long as the appropriate risk assessment and performance level calculations have been carried out, so not designed like the Boing anti stall system.

 

Some while ago I started a thread on EVs apparently becoming immobilised due to battery or other failures.

https://engx.theiet.org/f/discussions/28694/evs-immobilised-by-flat-batteries-or-breakdowns

The new car has a DSG transmission and the selector lever is locked in Park when the ignition is switched off. It requires 12V to be available to release it, so flat battery and the car is immobilized. Reading deeply in the handbook it can be released with a screwdriver (supplied with the car but buried under the spare wheel) by opening a flap in front of the (conventional) hand brake lever. Who, other than an Aspergers spectrum engineer, would actually look that up?

Parents
  • I tried out the Lane Keeping Assist in the snow this weekend. I was a little nervous of how it would join in on a twisting snow covered mountain pass (Julier in this case). In general it was ok but got somewhat confused when the road became 4 black stripes on a white background. It also tried to follow the tyre tracks from the bus in front which swung to the left and then turned off right. Finally it announced that it was no longer available, leaving an orange warning triangle on the instrument display.

    Like my previous diesel the 1.0 TSI engine struggled to produce enough waste heat to warm the cabin. It took around 10 km at 80 km/h on a level road before the engine reached working temperature. That would be a significant battery drain for an EV.

Reply
  • I tried out the Lane Keeping Assist in the snow this weekend. I was a little nervous of how it would join in on a twisting snow covered mountain pass (Julier in this case). In general it was ok but got somewhat confused when the road became 4 black stripes on a white background. It also tried to follow the tyre tracks from the bus in front which swung to the left and then turned off right. Finally it announced that it was no longer available, leaving an orange warning triangle on the instrument display.

    Like my previous diesel the 1.0 TSI engine struggled to produce enough waste heat to warm the cabin. It took around 10 km at 80 km/h on a level road before the engine reached working temperature. That would be a significant battery drain for an EV.

Children
  • Not tried it in snow yet, normally you have to watch the little sticks at the edge on the hills around here (no pavements), as you speed past the grit lorry in the ditch (yes seen that).

    With regard to EV range, my rule of thumb is start with manufacturers range, reduce by 1/3 for real world most of the year, reduce by half once temperature gets to around freezing. Heaters really hammer the battery plus the cold reduces capacity, strange they don't seem to broadcast that.......

  • In my very limited experience, that's a bit pessimistic.  I've only had my EV a few weeks, and done one long journey in it, in temperatures about 2°C.

    The car's advertised range is 235 miles.  My journey was about 120 to 125 miles, and I got back with 40% charge left.

    But it will depend a lot on how you drive.  Not knowing the car, I stuck to A roads and avoided the dual carriageway and motorway route.

  • Was that 40% usable charge or total charge? As I understand it you are not supposed to run the battery below a certain level (10%, 20% ???)

  • Not heard of that before - most batteries like to be fully cycled.  There is a recommendation for "battery life" not to routinely charge it to 100% unless you need that for a trip.  So mine goes to 90%.  Obviously no idea what long term difference this makes. I have run mine down to zero to get home without any ill effects (so far)

  • Yes its all in how you drive and how vicious the regen is set.  Speed above 70mph seems to hit the range (wind drag), heaters and other ancillaries do too. How many stop/starts and accelerations - and how gently you do them makes a difference to power consumption.  40% left seems a reasonable result for winter driving based on my experience too.  Clearly it is a "best guess" based on history as the car has no idea how you will drive/need to drive over future. 

  • Was that 40% usable charge or total charge? As I understand it you are not supposed to run the battery below a certain level (10%, 20% ???)

    That depends how cautious you want to be.  The manufacturers already allow a good safety margin at the top and bottom end of the charge range.  So when it says you have 0% left, it isn't really flat.