Hi all,
Im michele from italy and Im developing a racing simulation web oriented, and i would like to ask you help cause im experiencing some problems in implementing the clutch.
First of all i have to thank you all cause your forum is a invaluable source for a developer.
now my help request:
Im having serious difficulties in developing the clutch, i cant make it work like i would.
im modelling the clutch like a viscous coupling, "stealing" the idea from vdrift.
the code is:
Code:
float averageWheelsAngularVelo = 0;
foreach(Wheel w in poweredWheels)
averageWheelsAngularVelo += w.angularVelocity * drivetrainFraction;
ClutchSpeed=averageWheelsAngularVelo* ratio; // wheels average speed *ratio
ClutchTorque = clutch.GetTorque(engineAngularVelo, ClutchSpeed,engineTotalTorqueMax);
engineTorque = CalcEngineTorque(rpm) * throttle;
engineFrictionTorque=CalcEngineFrictionTorque(rpm);
if (clutch.IsLocked())
TransferedTorque=engineTorque;
else
TransferedTorque=ClutchTorque;
engineTotalTorque = engineTorque - engineFrictionTorque - ClutchTorque;
// update engine angular velo
engineAngularVelo += (engineTotalTorque) / engineInertia * Time.deltaTime;
if (ratio != 0 && clutch.GetClutchPosition()!=0) //clutch engaged or engaging
{
// Apply torque to wheels
foreach(Wheel w in poweredWheels)
{
lockingTorque = (averageWheelsAngularVelo - w.angularVelocity) * differentialLockCoefficient;
w.drivetrainInertia = inertia * drivetrainFraction;
w.driveFrictionTorque = engineFrictionTorque * Mathf.Abs(ratio) * drivetrainFraction;
w.driveTorque = TransferedTorque * ratio * drivetrainFraction + lockingTorque;
slipRatio += w.slipRatio * drivetrainFraction;
}
}
the GetTorque function is:
Code:
// clutch is modeled as limited highly viscous coupling
public float GetTorque ( float n_engine_speed, float n_clutch_speed, float engine_max_torque)
{
torque_capacity=1.25f*engine_max_torque;
nengine_max_torque=engine_max_torque;
engine_speed = n_engine_speed;
clutch_speed = n_clutch_speed;
new_speed_diff = engine_speed - clutch_speed;
locked = true;
if (clutch_position ==0) {
locked = false;
return 0;
}
else{
max_torque = clutch_position * torque_capacity;
friction_torque = max_torque* (new_speed_diff/factor); // viscous coupling (locked clutch)
if (friction_torque > max_torque) // slipping clutch
{
friction_torque = max_torque;
locked = false;
}
else if (friction_torque < -max_torque) // slipping clutch
{
friction_torque = -max_torque;
locked = false;
}
//friction_torque =Mathf.Min(engine_max_torque,friction_torque);
last_torque = friction_torque;
return friction_torque;
}
}
as you can see Im using a "factor" to decrease the speed_diff between engine and the clutch (new_speed_diff/factor), cause without that clutch is always slipping (new_speed_diff is always >1). the problem is that this is a patch, and i have to find the right factor for every car and engine i put in my sim.
Probably i need a function that update the engineangularvelo while engaging, but i really dont know if this is the right way and how to implement it.
Can someone help me please??
PS: if someone is interested this is the link of a demo of my sim:
http://migliortestesso.com/test/test.html
you can play it directly online, you dont have to donwload and install anything, excpet for the unity3d plugin, a plugin like flash but optimized for 3d graphics.ù
thank you all
michele
