Real-Time Physics Simulation Forum

hi

you have 2 possibilities with btHingeConstraint

joint->setLimit(desiredAngle,desiredAngle,0.0, 1.0,0.0);

or

velocity = (desiredAngle - currentAngle)/timeStep;
joint->enableAngularMotor(true,velocity,10000000);

be careful with solverInfo.m_numIteration, solverInfo.m_erp and timeStep

I need it as quality criterion for evolutionary algorithm

yes you are right, I am going to use "the sum of impulse" instead of "the sum of impulse^2"

so my problem is still there : how to get efficiently after each step the sum of [hingeJoint 6th row].appliedImpulse ?

tks

yes, I agree with you but here I consider 1/ timeStep^2 as a constant

I find what value I had to sum / save to get total energy applied to hinge joints : btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlyIterations(...) { float totalEnergy = 0; for ( iteration = 0;iteration<infoGlobal.m_numIterations;iteration++) { .... ///solve all joint constraint...

Hi, I would like to know how to get the total energy applied by motors to each hinge joint of my simulation, I can get it like that in bullet 2.73 : // before the Step : for (int = 0; i < nb_joint; i++) { joint[i]->motorImpulseInThatStep = 0; } // modification of btHingeConstraint::solveConstraintOb...

thank you to have answered, I have : core2 duo T5xxx, windows vista, bullet 2.74, release -O2, collision disabled between linked bodies and the log I get : Profiling: Root (total running time: 1251.426 ms) --- 0 -- internalSingleStepSimulation (0.08 %) :: 1.#IO ms / frame (1 calls) Unaccounted: (99....

Hello, I made a very simple simulation of a robot (a dog) with 14 hinge joints, each body is a cube, except the foots that are spheres (for the collision with the floor), the floor is a cube I found that to get joints' error smaller ( < 0.001 radian) I had to set timeStep = 0.001 , and the solver.nu...

you could add in btRigidBody.h :

class btRigidBody {
...

btVector3 getTotalForce()
{
return m_totalForce;
}


btVector3 getTotalTorque()
{
return m_totalTorque;
}

}

Hello, I'm still trying to understand how joints are corrected in Bullet and in physic simulation in general in btJacobianEntry(...) there is a number m_Adiag calculated as follow : with btVector3 currentAxis = (1,0,0), then (0,1,0) and then (0,0,1) btVector3 A_ContactPos = A_jointPosWorld - A_cente...

hello, I have to understand the calculus used for solving constraints in Bullet, for a student project my first question is : in btPoint2PointConstraint::solveConstraintObsolete (btPoint2PointConstraint is the easier to start with) you find that code : for (int i=0;i<3;i++) { /* blah blah blah */ bt...