WIP try a default of zero

RobotLocomotion · Mar 28, 2024 · 4940ea6 · 4940ea6
1 parent b57008f
commit 4940ea6
Show file tree

Hide file tree

Showing 3 changed files with 5 additions and 11 deletions.
diff --git a/multibody/plant/multibody_plant.h b/multibody/plant/multibody_plant.h
@@ -1159,8 +1159,7 @@ class MultibodyPlant : public internal::MultibodyTreeSystem<T> {
   /// @param[in] M_BBo_B
   ///   The SpatialInertia of the new rigid body to be added to `this`
   ///   %MultibodyPlant, computed about the body frame origin `Bo` and expressed
-  ///   in the body frame B. When not provided, defaults to a nominal non-zero
-  ///   value.
+  ///   in the body frame B. When not provided, defaults to ...
   /// @returns A constant reference to the new RigidBody just added, which will
   ///          remain valid for the lifetime of `this` %MultibodyPlant.
   const RigidBody<T>& AddRigidBody(
@@ -1206,8 +1205,7 @@ class MultibodyPlant : public internal::MultibodyTreeSystem<T> {
   /// @param[in] M_BBo_B
   ///   The SpatialInertia of the new rigid body to be added to `this`
   ///   %MultibodyPlant, computed about the body frame origin `Bo` and expressed
-  ///   in the body frame B. When not provided, defaults to a nominal non-zero
-  ///   value.
+  ///   in the body frame B. When not provided, defaults to ...
   /// @returns A constant reference to the new RigidBody just added, which will
   ///          remain valid for the lifetime of `this` %MultibodyPlant.
   /// @throws std::exception if additional model instances have been created

diff --git a/multibody/tree/rigid_body.cc b/multibody/tree/rigid_body.cc
@@ -65,9 +65,7 @@ RigidBody<T>::RigidBody(const std::string& body_name,
 
 template <typename T>
 SpatialInertia<double> RigidBody<T>::MakeNominalSpatialInertiaForConstructor() {
-  const double mass = 1.0;
-  const double radius = 0.0625;
-  return SpatialInertia<double>::SolidSphereWithMass(mass, radius);
+  return SpatialInertia<double>::Zero();
 }
 
 template <typename T>

diff --git a/multibody/tree/rigid_body.h b/multibody/tree/rigid_body.h
@@ -197,8 +197,7 @@ class RigidBody : public MultibodyElement<T> {
   ///   A name associated with this body.
   /// @param[in] M_BBo_B
   ///   Spatial inertia of this body B about the frame's origin `Bo` and
-  ///   expressed in the body frame B. When not provided, defaults to a nominal
-  ///   non-zero value.
+  ///   expressed in the body frame B. When not provided, defaults to ...
   /// @note See @ref multibody_spatial_inertia for details on the monogram
   /// notation used for spatial inertia quantities.
   explicit RigidBody(const std::string& body_name,
@@ -214,8 +213,7 @@ class RigidBody : public MultibodyElement<T> {
   ///   The model instance associated with this body.
   /// @param[in] M_BBo_B
   ///   Spatial inertia of this body B about the frame's origin `Bo` and
-  ///   expressed in the body frame B. When not provided, defaults to a nominal
-  ///   non-zero value.
+  ///   expressed in the body frame B. When not provided, defaults to ...
   /// @note See @ref multibody_spatial_inertia for details on the monogram
   /// notation used for spatial inertia quantities.
   RigidBody(const std::string& body_name, ModelInstanceIndex model_instance,