How the torque is calculate between an interval of points

[nonobecane]

How the torque is calculate between an interval of points ?
I try to make an electrical car with a constant torque

In the section engine if i wrote :

Code: Select all

      <section name="data points">
         <section name="1">
            <attnum name="rpm" unit="rpm" val="1"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="2">
            <attnum name="rpm" unit="rpm" val="5000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
      </section>

The engine behavior is not the same than if i wrote :

Code: Select all

      <section name="data points">
         <section name="1">
            <attnum name="rpm" unit="rpm" val="1"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="2">
            <attnum name="rpm" unit="rpm" val="100"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="3">
            <attnum name="rpm" unit="rpm" val="500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="4">
            <attnum name="rpm" unit="rpm" val="1000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="5">
            <attnum name="rpm" unit="rpm" val="1500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="6">
            <attnum name="rpm" unit="rpm" val="2000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="7">
            <attnum name="rpm" unit="rpm" val="2500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="8">
            <attnum name="rpm" unit="rpm" val="3000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="9">
            <attnum name="rpm" unit="rpm" val="3500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="10">
            <attnum name="rpm" unit="rpm" val="4000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="11">
            <attnum name="rpm" unit="rpm" val="4500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="12">
            <attnum name="rpm" unit="rpm" val="5000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
      </section>

Thanks for your answers

[simon-2]

that sounds strange..? even if i don't know the corresponding code, i think all common means of interpolation (linear or xth order) should give the same result in this case..?

[Sumer]

Hi,

This is exceptionally decent and wonderful post.
I am very happy joined this forum.
I like it exceptionally much....!!!!


Thanks alot...

[simon-2]

have a look at engine.cpp:

Code: Select all

Tq_max = engine->rads * curve->data[i].a + curve->data[i].b;

thus linear interpolation where a and b are previously eveluated:

Code: Select all

data->a = (edesc[i+1].tq - edesc[i].tq) / (edesc[i+1].rpm - edesc[i].rpm);
data->b = edesc[i].tq - data->a * edesc[i].rpm;

so a is slope between two points (which should always be 0 in your case), b is corresponding y-intercept (which should always be 300 in your case).

This is the same for simuv4 and simuv2.1, so i still wonder why you get different results..?

[nonobecane]

Thank you Simon for yout answer.

Me too, I don't know why...
I test with simu v4
In the first example the car is uncontrollable, the engine climbs slowly between 0 to ~1500 rpm and after it takes instantly 5000rpm
Also I test with a third point at 1500rpm :

Code: Select all

      <section name="data points">
         <section name="1">
            <attnum name="rpm" unit="rpm" val="1"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="2">
            <attnum name="rpm" unit="rpm" val="1500"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
         <section name="3">
            <attnum name="rpm" unit="rpm" val="5000"/>
            <attnum name="Tq" unit="N.m" val="300"/>
         </section>
      </section>

Then the engine climbs slowly between 0 to ~3000 rpm and after it takes instantly 5000rpm

mystery and gumdrop (it's a french expression )