Drive and Brake

Hey, I'm unable to get appropriate acceleration and deceleration.

The Simulation im working on is for a mobility scooter, which are limited to 10km/h, and I have set the gearbox pretty faithfully i think. Its an electric motor and I think they're pretty much on/off throttle


void CGameObjectScooter::InitMotor()
{
/*
Initialise the scooter's motor - The nxOgre motor class is designed around a traditional
gearbox/engine, but we are setting it up for a more digital/electrical motor as in a
mobility scooter
*/

// Construct the torque curve
m_nxoVehicle->mMotor->_torqueCurve.insert(0, 0);
m_nxoVehicle->mMotor->_torqueCurve.insert(1, 500); // 1 Gear setting at 500rpm - an estimate

// The rev limits - we want these close together as we want on/off throttle control.
m_nxoVehicle->mMotor->_minRpm = 450.0f;
m_nxoVehicle->mMotor->_maxRpm = 500.f; // A slight curve - barest acceleration.

// Differential Ratio is the size of the main cog in the gearbox compared to the gears.
m_nxoVehicle->_differentialRatio = 1;

m_nxoVehicle->_transmissionEfficiency = 1.0f;

m_nxoVehicle->mGear[0] = 2; // Gear cog is half as big as the main cog.
m_nxoVehicle->mGearCount = 1;
m_nxoVehicle->mReverseGear = -2;

m_nxoVehicle->_maxVelocity = 10;
}
Honestly, acceleration/speed seems fine, though it seems rev limited, and the top speed flag doesnt seem to do much.

My real problem is in braking - whether I roll to a stop, or apply the brakes, it slows down at the same rate almost.

// We process explicit braking first because it brakes harder than just "letting go"
// Explicit braking
if (m_inputreader->isKeyDown(KC_DOWN))
{
m_objScooter->GetVehicle()->drive(0, 1);
}

if (m_inputreader->isKeyDown(KC_UP))
{
m_objScooter->GetVehicle()->mCurrentGear = 0;
m_objScooter->GetVehicle()->drive(1, 0);
}
else
{
// Implicit braking
m_objScooter->GetVehicle()->drive(0, 0.5);
}

// Reverse
if (m_inputreader->isKeyDown(KC_R))
{
m_objScooter->GetVehicle()->drive(-1, 0);
}
Again, it does stop, but not quickly heh.

I suspect it may be something to do with global and/or tyre friction? I have set the default material to 1 in both dynamic and static friction, though tbh im not sure exactly which one applies here, as it's between a dynamic body(the wheel) and a static body(the world mesh).

Any suggestions?

Cheers, Geoff

Perhaps you could cheat and increase the brake power by 10 fold.

I don't think to much friction would make much of a difference, but I know it's either static or dynamic, you can increase the friction above 1. So make it 20 or 30 and see what happens.

However as I hate to admit it the NxOgre vehicle prefab is very buggy at the moment, so I'm surprised you've got it working this far. Kudos!

heh yeh ive tried both of those while trying to suss it out, neither increasing the friction or increasing breaking power gets it slowing down properly.

I'm having a look through nxogre source currently so see if i can work it out myself but any ideas that I can try? If i forgot to mention im still using preview 2.0 btw as I'm pretty hesitant to swap over to the new Ogre hehe.

I dont have a working vehicle sample currently (as I've modified some of the nxogre vehicle functions - added additional parameters to functions, etc), but does the sample vehicle have this issue of no brakes?

cheers again betajaen

hmm well i tried changing the factor the breakpedal is multiplied by in the simulate source(originally 750) to 2750, and it was a drastic change in brakes heh - worked too heavily.

Set it back to 750, changed the numbers i was using for the break pedal to 2 instead of 1. works like a dream

Now i just have to stop a vehicle that ISNT under player control from rolling infinitely. Friction doesn't seem to be doing it.

Ahh good.

Bizzarly how it sounds Friction doesn't do a whole lot when it comes to largish things like your scooter , so what I'd do is increase the dampening (linear and angular) of wheels and the scooter and fiddle around with that.

I do recommend you upgrade to the CVS though, but it does require upgrading to the latest PhysX (which is untested). There are a few bugs (including a massive memory leak) that have been fixed, but it's up to you.

Enjoy!