backport bullet-featherstone solver iters

Signed-off-by: Ian Chen <[email protected]>

bullet-featherstone/src/Base.cc

@@ -45,10 +45,15 @@ WorldInfo::WorldInfo(std::string name_)
 
   // By default a large impulse is applied when collisions penetrate
   // which causes unstable behavior. Bullet featherstone does not support
-  // configuring split impulse and penetration threshold parameters. Instead the
-  // penentration impulse depends on the erp2 parameter so set to a small value
-  // (default is 0.2).
+  // configuring split impulse and penetration threshold parameters. Instead
+  // the penentration impulse depends on the erp2 parameter so set to a small
+  // value (default in bullet is 0.2).
   this->world->getSolverInfo().m_erp2 = btScalar(0.002);
+
+  // Set solver iterations to the same as the default value in SDF,
+  // //world/physics/solver/bullet/iters
+  // (default in bullet is 10)
+  this->world->getSolverInfo().m_numIterations = 50u;
 }
 
 }  // namespace bullet_featherstone