Adaptive Cruse Control
191
Now Implemented!
Description
Adaptive cruise control extends the standard cruise control to either follow a vehicle in front at a pre-set distance and/or slow down if a vehicle appears closer than a pre-set distance. The distance is typically speed-related, such that the faster the speed the larger the safety distance.
As an option to standard adaptive cruise control, a system of predictive power control monitors traffic ahead and possibly uses GPS to identify upcoming up or downgrades and adjusts the speed (within limits) to improve range by using regen when traffic slows and when approaching a downgrade. When approaching uphill climbs the speed may slow down to a lower speed limit to further improve range.
Competitive/Pricing/Notes
Generally available only as an option on high-end luxury cars. For example, the 2013 Lexus LS460 has the option ‘Pre-Collision System & Dynamic Radar Cruise Control’ for $1500.
Status
Now included with all new cars, built after Nov-2014.
Tags:
13 Comments
Two points: first, the regular CC should work at any speed including very slow speeds. Second, when activating the ACC the system should compute the distance to the car in front IN SECONDS and maintain that spacing IN SECONDS as the speed changes. IE the driver gets to choose the spacing at whatever interval he feels comfortable with (perhaps within very liberal limits). And it should work down to zero speed: if the guy in front stops the Tesla should stop a few inches behind; when he starts up again the Tesla should start up immediately keeping that same spacing as above.
HJad this feature on the 2002 Lexus LS430 I, "Traded in" for my 2014 Model S. The Smart Cruise is the only feature that I really miss on the Tesla. Speed adjustments are not abrupt but are rather gentle and probably would yield better energy usage relative to manual driving.
Adaptive Cruise Control = DRIVER. If you are in traffic, cruise control shouldn't be on. To me it is a feature that just leads to a less attentive driver.
Related item: Static Cruise Control
Here's an update on cruise control as currently implemented in the Model S: Cruise Control Explained. Quoting from that site:
First of all, the cruise control should smoothly transition between speeds and not jump at the target speed full throttle. That's neither elegant nor economical and may actually even be dangerous. I know other cars that have a tendency to do that, but they are usually much less powerful than a Model S, so it's less of an issue there.
Moreover, as an extension to Adaptive Cruise Control as it is suggested by the original post, which adapts to traffic ahead, I would like to suggest a variation of cruise control that also adapts to the terrain to maximize range. Mercedes offers this kind of technology for their big rigs. They call it Predictive Powertrain Control and claim it improves range by 3% over conventional cruise control:
Mercedes actually uses GPS data to anticipate, among other things, uphill and downhill sections, but that's not even necessary. Experience from Roadster drivers has shown that they get better range if they try to keep the energy consumption constant, rather than keeping speed constant, which is what traditional cruise does. That's what cruise control should do in a Tesla, within some limits of course.
Thus, when setting cruise speed, the system should take this as a desired kWh/mile setting (i.e., the energy required to travel at the desired speed on a level road) plus some lower and upper speed limits (e.g., 6 mph below and above the set speed). Now, when approaching an uphill section, the car approaches at the set speed and uses its kinetic energy to continue traveling at the same kWh/mile, until the lower limit is met. The cruise will than apply more power to keep the speed from falling below that lower limit. On downhill sections, the cruise will make the best use of the potential energy by allowing the car to go faster than the set speed at the same constant kWh/mile. Only when speed approaches the upper limit, the car will lower the power input and eventually apply regen to keep from exceeding the upper speed limit.
In particular, when an uphill follows a downhill, this technique converts potential energy into kinetic energy during the downhill and uses that to make the first part of the uphill. This way, by modulating speed, the kWh/mile in a hilly terrain will much more closely match the kWh/mile in a level terrain, without compromising the average speed more than necessary.
This suggestion is based on this thread in Tesla's own forums.
Moderator: I wonder if this suggestion warrants its own Feature entry?
One comment on the cruise, which is probably intentional for every day driving, but slightly counterproductive when you’re trying to conserve battery. When you change speed, the car applies liberal amounts of accelerator or decel to get to the desired speed almost immediately, and then jumps back to the steady state condition. And with 416HP and 443lb ft of torque on tap, it could be considered overkill, or at least not how Grandpa (or Grandma) would drive.
First of all, the cruise control should smoothly transition between speeds and not jump at the target speed full throttle. That's neither elegant nor economical and may actually even be dangerous. I know other cars that have a tendency to do that, but they are usually much less powerful than a Model S, so it's less of an issue there.
Moreover, as an extension to Adaptive Cruise Control as it is suggested by the original post, which adapts to traffic ahead, I would like to suggest a variation of cruise control that also adapts to the terrain to maximize range. Mercedes offers this kind of technology for their big rigs. They call it Predictive Powertrain Control and claim it improves range by 3% over conventional cruise control:
As a result, and thanks to its profound understanding of both the vehicle and the route, this intelligent cruise control system with transmission intervention delivers a driving performance that could only be matched by an extremely motivated truck driver with an exceptional level of concentration.
Mercedes actually uses GPS data to anticipate, among other things, uphill and downhill sections, but that's not even necessary. Experience from Roadster drivers has shown that they get better range if they try to keep the energy consumption constant, rather than keeping speed constant, which is what traditional cruise does. That's what cruise control should do in a Tesla, within some limits of course.
Thus, when setting cruise speed, the system should take this as a desired kWh/mile setting (i.e., the energy required to travel at the desired speed on a level road) plus some lower and upper speed limits (e.g., 6 mph below and above the set speed). Now, when approaching an uphill section, the car approaches at the set speed and uses its kinetic energy to continue traveling at the same kWh/mile, until the lower limit is met. The cruise will than apply more power to keep the speed from falling below that lower limit. On downhill sections, the cruise will make the best use of the potential energy by allowing the car to go faster than the set speed at the same constant kWh/mile. Only when speed approaches the upper limit, the car will lower the power input and eventually apply regen to keep from exceeding the upper speed limit.
In particular, when an uphill follows a downhill, this technique converts potential energy into kinetic energy during the downhill and uses that to make the first part of the uphill. This way, by modulating speed, the kWh/mile in a hilly terrain will much more closely match the kWh/mile in a level terrain, without compromising the average speed more than necessary.
This suggestion is based on this thread in Tesla's own forums.
Moderator: I wonder if this suggestion warrants its own Feature entry?
