General > General Technical Chat

Throttle Controllers

<< < (4/8) > >>

David Hess:

--- Quote from: james_s on April 01, 2021, 08:27:01 pm ---They did that on old cars too. I remember discussing this a while back with a friend, he was talking about a car someone he knew had in the 80s that had a really aggressively tuned throttle, it was done so that if you just touched the gas from a stop it would feel powerful, puttering around town it gave that feeling of "whoa, this thing really wants to go!" but then if you actually stomp on it, it would pretty much run out of steam. It was not a very powerful car, it was just tuned to create the illusion of being powerful.
--- End quote ---

I am not surprised they would do something like that.  They play that game with modern electronics also.  For example cell phone signal level bars have their dynamic range altered so that they are more likely to show maximum indicating a good connection even when it is poor.

Old enough cars had progressive carburetors so at least you could feel the additional resistance when the next set of butterfly valves opened.

SilverSolder:

Many cars are tuned to feel powerful by applying a lot of throttle at the beginning of the pedal movement.   This is exactly what you don't want for fine control in snow or slippery conditions, of course...   

hans:

--- Quote from: SilverSolder on April 01, 2021, 02:26:42 am ---Applications engineers that work on the engine management systems of modern cars spend a LOT of time getting the "feel" of the accelerator "just so".  This is mostly done by testing on the track and on the road...  after all, only a human driver can tell you how the accelerator "feels".

And the "feel" that they aim for will be different depending on the target market.   The electronic throttle in a Mustang GT will not have the same goals for throttle response as a Toyota Camry!  :D

--- End quote ---

And on high-end cars they do this mapping or tuning for both "sports" or "comfort" driving operation as well.

Technically speaking you could just measure the throttle position, scale it to 0 ... 1, and then apply a sqrt() (or any fractional power for that matter) function on it to incredibly make it more punchy at the low end of the curve. Likewise if you want to soften it, you could square (or any power between 1 and 2) the value to make it incredibly slow at the low end. In that regard, these after market devices are not rocket science. They are purely an illusion or perhaps even a driver aid for economical driving.

IMO: If there is one throttle curve that is 'correct' or "ideal"; then tune the output of the drivetrain (e.g. if you have hybrid systems) to deliver a certain torque demand. Then linearize the throttle position to the capabilities of the drivetrain, both in retardation as in acceleration. Depending on how you scale the capabilities, you could even make it independent of engine rpm, vehicle gear or vehicle speed (as that will naturally increase vehicle retardation). The upside is that torque is what you feel will push you back into your seat, so will be relevant in feedback to the driver. You could make that feeling very predictable without knowing what the drivetrain under the hood is doing. The downside is that at certain speeds the drivetrain is not able to always deliver that torque demand.
Or just buy an electric motor.. I believe those are typically quite linear and ideal :-DD

Anything that makes that ideal throttle response softer/harder is just market tailoring torwards comfort or sport packages.


--- Quote from: David Hess on April 01, 2021, 11:36:46 pm ---
--- Quote from: james_s on April 01, 2021, 08:27:01 pm ---They did that on old cars too. I remember discussing this a while back with a friend, he was talking about a car someone he knew had in the 80s that had a really aggressively tuned throttle, it was done so that if you just touched the gas from a stop it would feel powerful, puttering around town it gave that feeling of "whoa, this thing really wants to go!" but then if you actually stomp on it, it would pretty much run out of steam. It was not a very powerful car, it was just tuned to create the illusion of being powerful.
--- End quote ---

I am not surprised they would do something like that.  They play that game with modern electronics also.  For example cell phone signal level bars have their dynamic range altered so that they are more likely to show maximum indicating a good connection even when it is poor.

Old enough cars had progressive carburetors so at least you could feel the additional resistance when the next set of butterfly valves opened.


--- End quote ---

I recognize my Ford Fiesta in this. On the lower half of the RPM range, it's already pulling full torque with 1/3 or 1/4 throttle position. The rest of the pedal is dead. Doesn't do anything. :palm:

SilverSolder:

--- Quote from: hans on April 02, 2021, 08:11:11 am ---[...]
IMO: If there is one throttle curve that is 'correct' or "ideal"; then tune the output of the drivetrain (e.g. if you have hybrid systems) to deliver a certain torque demand.
[...]

--- End quote ---

That is pretty much exactly how the throttle works in my hybrid Ford - which is extremely good in snow and ice because the torque can be controlled almost perfectly to the point just before spinning the wheels in all but the most extreme slippery conditions.  During snow storms, I have rescued a lot of stuck 4wd vehicles with this car, where the owners got a little overconfident! - my favourite comment from one guy, looking down at my wheels, "Are those summer tires?!?"  (yes, they were!)

Sal Ammoniac:

--- Quote from: amyk on March 31, 2021, 12:25:29 am ---That said, I suspect drive-by-wire is more for reducing emissions than anything else - and of the cars that I've tried which have it, there is a noticeable lag between punching the pedal and the engine responding. This is especially noticeable with a diesel. They deliberately limit the acceleration of the engine below the smoke-point.
--- End quote ---

I've never driven a diesel, so I have no experience with how drive-by-wire works in that scenario, but I can tell you that on an electric car like my Tesla, there is no noticeable lag at all between punching the pedal and the car responding. It's much better than my previous IC car, which did have some lag. Plus you can tune the response as well, including turning off "creep" so the car doesn't move with your foot off the pedal like IC cars with automatic transmissions do.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod