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Old 9th July 2014, 14:11   #16
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

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Originally Posted by Jeroen View Post
Even though initially it was related to a floormat it would have to be some thick mat before it would hinder the brake pedal coming down.

Jeroen
Slightly . I have had a very scary experience with the brake pedal getting stuck, driving a rented Ford 500 in the US. Some one had left a coke bottle in the driver's foot well/ under the drivers seat. The bottle rolled over and lodged itself under the brake pedal in such a way that the brake pedal would simply not push down.

Fortunately, I wasn't going too fast and was able to slow down and stop using a combination of the handbrake and engine braking (using lower gears).

Lesson learnt: Always look for loose objects in the drivers foot well when driving a borrowed car.

Last edited by torque!! : 9th July 2014 at 14:14. Reason: Updates
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Old 9th July 2014, 14:21   #17
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

The essential software has already been there in Petrol and Diesel injection ECUs for the last 20 years or so: Cruise Control override / cancel when Brake or Clutch pedal is pressed. Cruise Control modulates "Driver Demand" number used for injection calculation, without the Acc pedal being pressed. Implementing BTO would be quite simple, actually.

What needs a lot of research and testing is the humongous number of 'Use Cases' associated with these systems, just so that an intended 'good to have' feature doesn't turn into a massive liability for the car manufacturer - for want of enough thought.

'Brakes also not working' is usually a (panic-driven) expression that actually conveys 'Braking is not effective'. This is actually in comparison with the braking profile drivers store in the brain without thinking - I press brake this much, the car decelerates that much. Any violation of that profile, like when the engine is continuing to deliver significant power to wheels enough to overcome normal brake force, causes an immediate panic stations in the brain. Used to happen with old carburetted engines too, but then with Amby and Padmini, for example, one quickly learnt to press clutch to get yourself out of those transient troubles.
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Old 9th July 2014, 14:35   #18
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

Interesting. I recently was driving a ford figo diesel base variant on the highway and was gently left footing over high speed crests on the highway and noted the same orange warning light coming on
and repeated several times to confirm, the ecu is actually detecting left foot braking. but, i never lost any power or the engine go into limp mode. I regularly left foot brake on many cars (including many german premiums) and this was the first car in which i noticed this phenomena. I was thinking of searching about it and found this thread. Let the discussion continue and bring in more information.
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Old 9th July 2014, 16:40   #19
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Exclamation Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

I'm not too sure which all cars have this as a standard feature- my 2005 Octavia RS kills the accelerator if the brake is applied at the same time as the accelerator. Same for my W203. (I've tried this at the time of changing brake pads, as i used to do this procedure on our older cars to run in new brake pads- accelerator+brake at the same time.)

None of my cars give any info on the dash in such an instance.

Any car with a servo controlled throttle should have this as a fail safe (and in my opinion, would have this already present). I have a feeling this "technology" is already quite widespread.
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Old 9th July 2014, 16:57   #20
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

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Originally Posted by torque!! View Post
Slightly . I have had a very scary experience with the brake pedal getting stuck, driving a rented Ford 500 in the US. Some one had left a coke bottle in the driver's foot well/ under the drivers seat. The bottle rolled over and lodged itself under the brake pedal in such a way that the brake pedal would simply not push down.

Lesson learnt: Always look for loose objects in the drivers foot well when driving a borrowed car.
Very true! On a lsightly different note: Recently a commercial aircraft plummeted thousands of feet because a camera was left loose and got stuck under the joy stick.

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Originally Posted by DerAlte View Post
'Brakes also not working' is usually a (panic-driven) expression that actually conveys 'Braking is not effective'. This is actually in comparison with the braking profile drivers store in the brain without thinking - I press brake this much, the car decelerates that much. Any violation of that profile, like when the engine is continuing to deliver significant power to wheels enough to overcome normal brake force, causes an immediate panic stations in the brain. Used to happen with old carburetted engines too, but then with Amby and Padmini, for example, one quickly learnt to press clutch to get yourself out of those transient troubles.
Probably a very valid point. After a while that sort of gets hardcoded into your brain. Years ago I was talking to my wife about the ABS on her little car. She had no idea what I was on about. I asked if she never felt/heard the ABS coming in when she pressed the brakes really hard. No, no clue. So we went for a test drive and I found out that she never pressed the brake hard enough for the ABS to kick in. She thought she was pressing hard enough on the brakes, got quite a good deceleration going and left it at that.

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Originally Posted by jaideepshinh View Post
.
Any car with a servo controlled throttle should have this as a fail safe (and in my opinion, would have this already present). I have a feeling this "technology" is already quite widespread.
See DerAlte's post. for any car that has a cruisecontrol and a ECU:

Quote:
The essential software has already been there in Petrol and Diesel injection ECUs for the last 20 years or so: Cruise Control override / cancel when Brake or Clutch pedal is pressed. Cruise Control modulates "Driver Demand" number used for injection calculation, without the Acc pedal being pressed. Implementing BTO would be quite simple, actually.
So you don't need servo controlled throttle at all. You manipulate (close) the injection based on the brake pedel switch input.

All the sensors and input are there already, so it would most likely only require a software/function change.

Jeroen

Last edited by Jeroen : 9th July 2014 at 16:58.
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Old 9th July 2014, 17:22   #21
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

DerAlte's post is talking about "implementing" it, assuming my understanding of his post is correct.

My point is this- "BTO" has already been implemented from quite a while in many cars. We're trying to reinvent the wheel here by saying that all the sensors are in place and "BTO" should be easy to implement.


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Originally Posted by Jeroen View Post
See DerAlte's post. for any car that has a cruisecontrol and a ECU:
Jeroen
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Old 9th July 2014, 18:09   #22
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

yeah, even my 2007 Indica DICOR throws the engine warning when i try to drive hard around corners with left foot braking. Thought it was an issue until today, thanks for the inputs.
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Old 9th July 2014, 18:24   #23
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Thumbs up Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

Most VAG cars already have it. The story goes that they had a series of runaway engines in the 80's and implemented a switch to KILL the fly by wire throttle as soon as the brake pedal is touched. (Brake pedal activation switch in the pedal box)

This is true in the Rapid TDI I drive.
If I left foot brake the fuel is cut and even after I release the brake pedal it takes 1.5 seconds to resume fuel supply.

One of the solution given is to remove the brake light fuse if you want it to work with left foot braking. But cruise control doesn't work anymore.
And driving without brake lights is a terrible idea.

The alternate solution is to pump the throttle once after you left foot brake, that tells the ECU that you still want the engine to accelerate and works beautifully in my car as the throttle response is terrible anyway.

I think the VAG solution is quite well thought out.

If no input is detected engine defaults to idle when brake is pressed.

If a fresh input is detected after brake is pressed its not a malfunction and the ECU can continue to accelerate the car, allowing some left foot braking.
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Old 9th July 2014, 18:34   #24
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

Quote:
Originally Posted by jaideepshinh View Post
... (I've tried this at the time of changing brake pads, as i used to do this procedure on our older cars to run in new brake pads- accelerator+brake at the same time.) ...
Quite likely your observation is of a different phenomenon - which just happens to be feeling similar to BTO. No, those 2 cars don't have BTO, nor anything similar. Nor is BTO testing the process that you use.

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Originally Posted by jaideepshinh View Post
... None of my cars give any info on the dash in such an instance. ...
Nothing significant to be informing the driver. Not everything is annunciated to driver - pointless. What will the driver do - keep looking at the dash instead of driving?

Quote:
Originally Posted by jaideepshinh View Post
... Any car with a servo controlled throttle ...
Quote:
Originally Posted by Jeroen View Post
... So you don't need servo controlled throttle at all. ...
"Servo" is a vestigial term today. In reality, the control of "throttle" (the flap in throttle body that controls air). But as a system term, the throttle body system can be called a 'servo' system as it is a participant in a closed-loop control algorithm. "Servo" earlier was a term used with Analog controls, one doesn't use it in the Digital Controls (ECU) world.

The term "Throttle" in BTO is a term covering both Acc Pedal as well as the Throttle flap. When Driver Demand goes to 0, the Throttle Position is set to Idling for engine braking, or slightly higher for coasting.

Quote:
Originally Posted by Jeroen View Post
... All the sensors and input are there already, so it would most likely only require a software/function change. ...
Correct.

Quote:
Originally Posted by jaideepshinh View Post
... My point is this- "BTO" has already been implemented from quite a while in many cars. We're trying to reinvent the wheel here by saying that all the sensors are in place and "BTO" should be easy to implement.
It is your assumption, from observed behaviour, that BTO is implemented. If BTO is implemented, it will not be a manufacturer-specific feature. It will be a pseudo-standard, like Cruise Control, ABS, Airbags etc. are - doing the same thing in all cars without prejudice.
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Old 9th July 2014, 19:09   #25
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

DerAlte:

1. The similar "Phenomenon"- what exactly do you mean by Break- Throttle Override? Isn't that what is happening here, in literal terms? or is that some other technology which i am ignorant to?

2. How do you test BTO if you are not using your accelerator and brake simultaneously?

3. I appreciate your logic of not having to look at the dash continuously. This point of mine was in response to the post of another learned bhpian who was mentioning that his car shows a display in such a situation (4-5 posts behind)

4. Servo- that's interesting that its vestigial. considering that its a servomotor which is controlling the butterfly valve of the flap in the throttle body. Servomotors are the industrial standard for all CNC machines. You accelerator peddle has an encoder, which gives the position feedback to your ECU, which in turn sends the set point for the servomotor at the throttle body. Fuel injection pulse width is anyway calculated by the ECU based on air volume and lambda feedback (in addition to accelerator position, if available).

5. My point of BTO implementation is not that it is a standard for all automobiles; it is that its already in use by many manufacturers, for over 10 years at least. I find it weird that people are trying to reinvent it here.

6. If you are driving any similar car, please try it out and let me know your views on whether they have "anything similar" to BTO. I find it quite stupid how you gun these down without ever having tried this. I'm sure your assumption is based on googling it, and these manufacturers have not mentioned it in the features list- most likely because its not worthy of being called a feature.

I understand that you're probably not too happy with me at this point for differing in opinion. However, i'm here to spread whatever little knowledge i have, and not a an ego trampling competition, which is what i observe mostly happening here.

I suggest you try my experiment with these cars before replying to my post in haste.

Quote:
Originally Posted by DerAlte View Post
Quite likely your observation is of a different phenomenon - which just happens to be feeling similar to BTO. No, those 2 cars don't have BTO, nor anything similar. Nor is BTO testing the process that you use.

Nothing significant to be informing the driver. Not everything is annunciated to driver - pointless. What will the driver do - keep looking at the dash instead of driving?


"Servo" is a vestigial term today. In reality, the control of "throttle" (the flap in throttle body that controls air). But as a system term, the throttle body system can be called a 'servo' system as it is a participant in a closed-loop control algorithm. "Servo" earlier was a term used with Analog controls, one doesn't use it in the Digital Controls (ECU) world.

The term "Throttle" in BTO is a term covering both Acc Pedal as well as the Throttle flap. When Driver Demand goes to 0, the Throttle Position is set to Idling for engine braking, or slightly higher for coasting.

Correct.

It is your assumption, from observed behaviour, that BTO is implemented. If BTO is implemented, it will not be a manufacturer-specific feature. It will be a pseudo-standard, like Cruise Control, ABS, Airbags etc. are - doing the same thing in all cars without prejudice.
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Old 9th July 2014, 19:52   #26
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

Quote:
Originally Posted by DerAlte View Post
Quite likely your observation is of a different phenomenon - which just happens to be feeling similar to BTO. No, those 2 cars don't have BTO, nor anything similar. Nor is BTO testing the process that you use.

It is your assumption, from observed behaviour, that BTO is implemented. If BTO is implemented, it will not be a manufacturer-specific feature. It will be a pseudo-standard, like Cruise Control, ABS, Airbags etc. are - doing the same thing in all cars without prejudice.
Just a correction here. Both cars mentioned by Jaideep have BTO. The Skoda Octavia 2005 and mercedes C class W203.

http://www.briskoda.net/forums/topic...dal-over-ride/

Quote:
"Servo" is a vestigial term today. In reality, the control of "throttle" (the flap in throttle body that controls air). But as a system term, the throttle body system can be called a 'servo' system as it is a participant in a closed-loop control algorithm. "Servo" earlier was a term used with Analog controls, one doesn't use it in the Digital Controls (ECU) world.

The term "Throttle" in BTO is a term covering both Acc Pedal as well as the Throttle flap. When Driver Demand goes to 0, the Throttle Position is set to Idling for engine braking, or slightly higher for coasting.
Guys, I think too much thought is going into a simple thing. I'm pretty sure Jaideep has used the wrong word "Servo" here. He probably didn't know the exact jargon which is DBW or drive by wire.

Any car with drive by wire should be easy to have BTO which is what Jaideep is trying to say.
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Old 9th July 2014, 20:02   #27
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

This is a fantastic safety feature!

However, I do not think this is something new that came about after the sad "unintended acceleration" episodes in the US. As mentioned by others, many cars (even economy cars in India) have had this feature for quite a while.

For instance, the Hyundai i20 facelift has this feature (not sure if the pre-facelift versions have it), but only in petrol (for some strange reason). Hyundai calls it the "Smart Pedal" and has been tom-toming it as a "1st in segment" safety feature.

This is what the official Team-BHP review noted:

Quote:
• The i20 petrol (not the diesel) is equipped with a smart pedal system. In an emergency braking situation, inputs of the brake pedal will take precedence over the accelerator pedal.
http://www.team-bhp.com/forum/offici...ml#post2786429

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Originally Posted by Vid6639 View Post
Any car with drive by wire should be easy to have BTO which is what Jaideep is trying to say.
Absolutely! A drive-by-wire system is all that is required.

Last edited by RSR : 9th July 2014 at 20:13.
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Old 9th July 2014, 21:48   #28
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

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Originally Posted by LordSharan View Post
In case of manual, would it not be wise to use Engine braking? Shifting down to first gear may be and then re-engaging the clutch? Stopping from high speeds using coasting could take some time.
I assumed the only problem in the first post was a stuck throttle. Braking would seem ineffective at that point. Simultaneous stuck throttle and brake failure would be less probable.

By coasting, I meant driving after disconnecting engine power. You can brake normally once you got to the side of the road.

In case of brake failure alone, yes, one could use engine braking to slow down. In the end you would have to go to Neutral and engage the handbrake partly to stop completely.

But if you face stuck throttle and brake failure at the same time, best bet would be to pop it into Neutral and use partly engaged hand brake to slow down.

With the throttle open, you won't get much engine braking to begin with and will take a long time till you come to 1st. Say the throttle got stuck at 2500RPM when you were cruising in 5th gear, even if you shift down sequentially to 1st, you will still be at 2500RPM (speed depends on the car) and it won't go down naturally.

Quote:
Originally Posted by Vid6639 View Post
I'm pretty sure Jaideep has used the wrong word "Servo" here. He probably didn't know the exact jargon which is DBW or drive by wire.
I believe the term he was looking for was Stepper Motor.

Edit: BTW diesels have no problem with stuck throttles, since there would be no throttle. The ECU would just cut fuel when it senses both the A & B pedals are pressed. DBW would not be essential to have BTO. Throttle position sensor (basically any fuel injected vehicle) is enough hardware I think.

Last edited by bravo6 : 9th July 2014 at 22:00.
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Old 9th July 2014, 21:56   #29
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

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Originally Posted by bravo6 View Post

I believe the term he was looking for was Stepper Motor.
I just read Jaideep's second post and he was actually referring to the servo-motor of the throttle body. Makes sense. In case of Drive by wire accelerator position sensor send signal to ECU which controls the servo motor that opens/closes the throttle body as needed and control fuel injection.
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Old 9th July 2014, 22:53   #30
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Default Re: The End of Left-Foot Braking? BTO - Brake Throttle Override

OT: Yup! Both servo and stepper motor can get the job done in a DBW system, but servos are costlier.
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