Re: [Torcs-users] (Patch) Automatic gear shift

Hi David

I am currently looking into it (finally). I will probably apply the gear 
shifting part and the "speed" value (because it is used in  several 
places, so it probably makes sense).

I will not change the "I" though (12.0). You can adjust the inertia 
around the most important axis with the mass repartition coefficient 
from the xml. At some point it could make sense to make this 
configurable around all axis.

But first another improvement has to be done:
- Backport from simuv3/review/implement the use of a quaternion for car 
body rotations (will help at high bankings/steep slopes etc.), google 
for things like "quaternion rotation matrix gimbal lock".

There is another thing which is not perfectly handled, see 
SimCarCollideZ, but this is sort of "no use case", namely when the car 
body hits the floor very hard (no use case because in reality this just 
trashes the car).

Kind regards

Bernhard

On 10/26/2013 05:27 AM, David Savinkoff wrote:
> Bernhard Wymann wrote:
>> Hi David
>>
>> Thank you for the patch, it looks reasonable and I will take a note to
>> put it into 1.3.6.
>>
>> Best regards
>>
>> Bernhard
>>
>> On 10/09/2013 08:30 AM, David Savinkoff wrote:
>>> Hi Bernhard,
>>>
>>> This patch improves human automatic gear shifting, making controlled
>>> drifting in TORCS much better. TORCS currently shifts gears by using
>>> car->_speed_x (a single component of a 3D vector). This is correct
>>> only when the car is traveling in the direction that is pointed,
>>> not when drifting or flying off-angle. Loss of control can no longer
>>> be attributed to improper automatic down-shifting while drifting.
>>>
>>> BTW using x, y and z vector components work better than just x and y
>>> (I drove various tracks for the past day to test TORCS).
>>>
>>> Note that this patch is more-or-less a hack-ish proof of concept.
>>>
>>> TORCS has been my high velocity entertainment for four years.
>>>
>>> Thanks,
>>> David
>>>
>
> Hi Bernhard,
>
> Here is a new patch that incorporates my previous gear-shifting
> patch in a more generalized way, allowing for the speed calculation
> to be used throughout torcs (not only for gear shifting).
>
> I applied the speed calculation to steering for an improvement too.
> (I got a hint from speed-dreams for this one)
>
> Note the gear shifting improvement and steering improvement in:
> torcs-1.3.5-test1/src/drivers/human/human.cpp
>
> The speed calculation is also applied for improvements in:
> torcs-1.3.5-test1/src/libs/raceengineclient/raceengine.cpp
> torcs-1.3.5-test1/src/modules/graphic/ssggraph/CarSoundData.cpp
> torcs-1.3.5-test1/src/modules/graphic/ssggraph/grskidmarks.cpp
> torcs-1.3.5-test1/src/modules/graphic/ssggraph/grsmoke.cpp
>
> The speed calculation could also be applied for improvements in:
> torcs-1.3.5-test1/src/drivers
>
> The speed calculation is made in:
> torcs-1.3.5-test1/src/interfaces/car.h
> torcs-1.3.5-test1/src/modules/simu/simuv2/car.cpp
>
> A constant for the yaw, pitch and roll inertial moments were
> experimented with, and changed for an improvement in:
> torcs-1.3.5-test1/src/modules/simu/simuv2/car.cpp
> Maybe these values could be made user configurable.
>
> All of the improvements make for a better driving experience.
>
> Please try this patch. I developed these patches on a modified
> car4-trb1, and tested them on car5-trb1 afterwards.
>
> car5-trb1 works excellently, and I recommend you do some
> drift-passing on corners around the robots. Now you can
> realistically scramble to save your bacon after pushing it
> too far.
>
> Sincerely,
> David Savinkoff
>
> ps.  :)
>
> If the 12.0 constant used in the Inverse Moment of Inertia is
> mathematically derived and not negotiable, here is my argument:
>
> I tried 6.0 and found that the moment of inertia was too high,
> and 18.0 found it too low (subjectively tested by driving).
>
> Thus, 12.0 must be the best value since it is half-way-between.
>
> However, half-way-between seems to have the worst of too-high
> and too-low. It is perfectly-bad.
>
> So, maybe halfway between perfectly-bad and too-something is
> the answer...
>
> 15.0 is halfway between perfectly-bad (12.0) and too-low (18.0),
> and it seems to be approximately the best value.
>
>
> The Derivation of 15.28  :)
>
> Given that 12.0 is the mathematically correct constant
> for this inverse moment of inertia formula:
>
> Constant for Moment of Inertia = 1/12
>
> 1/12 * pi/4 = 0.06545 ; pi/4 [rads] works good and looks good too!
>
> 1/.06545 = 15.28
>
>
>
> ------------------------------------------------------------------------------
> October Webinars: Code for Performance
> Free Intel webinars can help you accelerate application performance.
> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from
> the latest Intel processors and coprocessors. See abstracts and register >
> http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktrk
>
>
>
> _______________________________________________
> Torcs-users mailing list
> Tor...@li...
> https://lists.sourceforge.net/lists/listinfo/torcs-users
>