Hill Hold Function

[brianoflondon]

Fully automatic hill hold in my 6 speed clutch less semi automatic Honda Civic though it wasn't perfect.

Fully automatic hill hold in Electric Renault Fluence ZE is perfect.

 

[strider]

I mentioned this to the TM folks at the PA drive event - it's an EV I want it to work like a freaking Segway. I want no creep and no movement of the car in ANY way unless I initiate it via the controls. If I come to a complete stop on a 45-degree hill and take my foot off the brake it should NOT move. It should be trivial to make this work w/ the motor - just apply enough power in the opposite direction to stop the rolling. Yes it will use power to do that but if you want to conserve every last electron just hold the brakes. Why is this difficult?

 

[Adm]

Why is this difficult?

I wouldn't be surprised if this would proved to be very easy. The bigger problem is that there are more than 10'000 other Model S clients that may not want exactly what you want.

 

[brianoflondon]

I mentioned this to the TM folks at the PA drive event - it's an EV I want it to work like a freaking Segway. I want no creep and no movement of the car in ANY way unless I initiate it via the controls. If I come to a complete stop on a 45-degree hill and take my foot off the brake it should NOT move.

What you're asking for defies the laws of physics and is not intuitive. It's also a pain in the arse if you want to reverse down a hill. Do you really want to select reverse and apply pressure to the accelerator to roll back slightly? How long should the car hold you? Indefinitely?

If you come to a stop on a 45-degree hill and remove pressure from the brakes, physics should kick in and roll you back UNLESS some other behaviour is designed. A manual car will roll back for sure. My EV holds for 2 seconds before gradually releasing the brakes.

What is a bit strange is Tesla not nailing this behaviour back in the Roadster days. I'm rather surprised this debate is ongoing now.

 

[doug]

On the Roadster you have a handbrake, so it's less of an issue.

For the Model S, I'd assume they'd use the electric parking brake (that extra set of calipers) for hill hold. But I can see how smoothness might be a concern since those might be more all-or-none rather than a gradual release.

 

[ElSupreme]

The hill hold in my Audi A3 is automatic. It has the DSG transmission and when stopped on a hill will apply just enough creep via the clutch to keep the car in place for a few seconds at which point it lets you roll backward to preserve the clutch. No brakes involoved.

No clutch in the Tesla makes this type of release pretty hard.

I mentioned this to the TM folks at the PA drive event - it's an EV I want it to work like a freaking Segway. I want no creep and no movement of the car in ANY way unless I initiate it via the controls. If I come to a complete stop on a 45-degree hill and take my foot off the brake it should NOT move. It should be trivial to make this work w/ the motor - just apply enough power in the opposite direction to stop the rolling. Yes it will use power to do that but if you want to conserve every last electron just hold the brakes. Why is this difficult?

AC Induction motors don't 'stall' well. Either they can't depends on control systems AND motor configuration. Also they use a lot of power and produce a lot of heat when doing this. The segway uses DC permanant magnet motors (I think I saw 'Servo') which work great at 0 speed.

For the Model S, I'd assume they'd use the electric parking brake (that extra set of calipers) for hill hold. But I can see how smoothness might be a concern since those might be more all-or-none rather than a gradual release.

I think this is probably correct. The parking brake to me looks like a 3rd caliper that is solenoid based. A simple on/off.

I don't have any problem with 'hill hold' as I drive a manual and rarely (about once a year) let the clutch out with a brake depressed. A little roll back isn't really a problem. You only roll back a couple of inches, and people don't stop that close to you.

 

[Thumper]

I fail to see why any company and especially Tesla should be asked by customers to create a device to compensate for people being too lazy and hidebound to put their left foot on the brake pedal when stopping on a hill! Tesla has better things to do with engineering talent and manufacturing capacity.

 

[jerry33]

I fail to see why any company and especially Tesla should be asked by customers to create a device to compensate for people being too lazy and hidebound to put their left foot on the brake pedal when stopping on a hill! Tesla has better things to do with engineering talent and manufacturing capacity.

I'm normally against two-foot driving but this seems like a no-brainer. Use the left foot for hill-holding.

 

[gmontem]

The need for a hill hold feature is to compensate for that "feature" of disallowing use of both feet for more than 3 seconds.
Sent from my HTC Titan using Board Express

 

[jerry33]

The need for a hill hold feature is to compensate for that "feature" of disallowing use of both feet for more than 3 seconds.

If you have one foot on the brake to hill-hold, why would the other foot be pressing the accelerator? There's obviously something here I'm not understanding.

 

[gmontem]

If you have one foot on the brake to hill-hold, why would the other foot be pressing the accelerator? There's obviously something here I'm not understanding.

Drive the >45 degree incline, busy streets of San Francisco to find out yourself. I'd recommend the tourist-infested Lombard Street, a few blocks before it goes crookedly downhill.
Sent from my HTC Titan using Board Express

 

[pilotSteve]

I fail to see why any company and especially Tesla should be asked by customers to create a device to compensate for people being too lazy and hidebound to put their left foot on the brake pedal when stopping on a hill! Tesla has better things to do with engineering talent and manufacturing capacity.

My BMW 5-series and wife's Lexus both have this feature. Its automatic, seamless and works perfectly intuitively. (actually the BMW jerks just a bit when releasing but then the brakes are not the smoothest in coming to a stop either. Awesome 80-5 mph stopping, crummy 5-0 IMO for smoothness). The point is this is another refinement that Tesla customers will expect to be there. The good news (posted previously) is that George B is well aware of these kind of competitive refinements and that Tesla is working on adding them. Not necessarily holding up deliveries (just my opinion) but working on make them 'perfect' before release.

 

[gg_got_a_tesla]

Drive the >45 degree incline, busy streets of San Francisco to find out yourself. I'd recommend the tourist-infested Lombard Street, a few blocks before it goes crookedly downhill.
Sent from my HTC Titan using Board Express

Don't mean to make light of the situation, George, but, waiting on the inclined uphill section of Lombard to get onto the crooked street is for tourists. Locals approach it on the flat Hyde St and then turn right onto the downslope crooked section

 

[Vger]

We live in a very hilly place with our Roadster 2.0, and I regularly deal with a steep uphill with a stop sign at the top, and the need to accelerate quickly onto a busy main road after the stop. It is quite easy to just balance the accelerator pedal with enough torque to keep the car essentially stationary, and then mash it to move off when the road clears. While this uses energy, it is a trivial amount. If it uses even 2 kW to hold on a vary steep hill for 60 seconds, that is 33.3 Wh, which is about 1/10 mile of range. Big deal. If that is too much, as others have said, use the left foot.

 

[contaygious]

I drive up SF hills everyday and although it's nice in my wife's mini, it's not too big a deal without hill assist as long as I'm not in a manual

 

[strider]

AC Induction motors don't 'stall' well. Either they can't depends on control systems AND motor configuration. Also they use a lot of power and produce a lot of heat when doing this. The segway uses DC permanant magnet motors (I think I saw 'Servo') which work great at 0 speed.

Hmm. Interesting angle. However there is a hill near my house that when I'm sitting at the traffic light is just the right angle to counter the creep in my Roadster and it will sit without touching the brake or accelerator. During rush hour it can be a long light and I've sat there for several minutes and haven't noticed a rise in motor temp. Maybe after a certain time it could engage the e-brake and then when you hit the accelerator coordinate the motor and e-brake release.

This is just one more of those things that an EV should be able to do better than an ICE.

 

[EVNow]

I don't know of an automatic hill hold/start that is enabled automatically. The parking brake can be used for hill holding by simply activating when stopped. When it is time to go just press the accelerator and the parking brake will release automatically (provided you have your seat belt on). In a fashion this automatic I suppose since you don't have coordinate releasing the brake.

Right - this is what I was referring to. We don't have this problem of the car going back in the time it takes to switch between the brake and the accelerator.

 

[brianoflondon]

I have a creeping and hill holding Renault Fluence ZE. I never really thought consciously about the behaviour till reading here: my car seems to have been designed to behave exactly like a traditional creeping automatic and that's why it felt very comfortable. As I posted above, the hill hold feature that holds the car with the brakes for 2 seconds before gradually releasing them (unless you press the accelerator yourself) seems to work perfectly.

It occurred to me while backing in to my car park space that I was using the brake to control this. I don't touch the accelerator at all as the creep speed in reverse is plenty fast enough.

What does the Tesla S do in reverse? Do you really have to use the accelerator to reverse slowly on the flat? That strikes me as a new skill drivers would have to learn.

 

[jerry33]

What does the Tesla S do in reverse? Do you really have to use the accelerator to reverse slowly on the flat? That strikes me as a new skill drivers would have to learn.

Most of my vehicles, until the Prius, were manual. No creep there and no problem reversing. Also no problem switching between manual and automatic. My opinion is that this is a solution in search of a problem. Creep is necessary in automatic transmissions to reduce lag time between pressing the go pedal and actually moving. It's a work-around to overcome a defect inherent to an automatic transmission. It shouldn't be a goal.

 

[brianoflondon]

Most of my vehicles, until the Prius, were manual. No creep there and no problem reversing. Also no problem switching between manual and automatic. My opinion is that this is a solution in search of a problem. Creep is necessary in automatic transmissions to reduce lag time between pressing the go pedal and actually moving. It's a work-around to overcome a defect inherent to an automatic transmission. It shouldn't be a goal.

All of the manuals I've driven would creep in reverse or first gear without use of the accelerator, certainly enough for most parking.

Changing the way cars behave in general serves little purpose. It just makes new people uncomfortable. I used to love fly-on fly-off handbrakes on track cars but I wouldn't want one on a road car!