Contact force + torque and the contact measured force + torque of a surface contact

[edward9503]

Contact force + torque and the contact measured force + torque of a surface contact

[edward9503]

@jhwangbo

[jhwangbo]

There is no reaction torque from a point. A point cannot apply torque.

You have to add all contact forces to get the sum.

[edward9503]

@jhwangbo
Thanks for the reply. In my code, the way to get the contact force for a surface contact is:

  size_t armEE_B_idx = anymals[1]->getBodyIdx("bracelet_link");
  armEEContactForceB_mrt.setZero(); 
  for(auto& contact_: anymals[1]->getContacts()) {
    if (contact_.skip()) continue; /// if the contact is internal, one contact point is set to 'skip'
      if (armEE_B_idx == contact_.getlocalBodyIndex()){
        armEEContactForceB_mrt = std::pow(-1, !contact_.isObjectA()) * contact_.getContactFrame().e().transpose() * contact_.getImpulse().e() / dt;
      }
  }

But the results turn out to be 3X1 vector, which is not for the corner point separately. In this case:

1. Is it the summed force of the surface contact?
2. How to get the corner point contact force separately?
   Thanks.

[jhwangbo]

1. if all four points are in contact, the will be in anymals[1]->getContacts(). Then you have to sum them up with your code
2. You are already doing that with your code