Name changes in support of composites to come

Author: sherm1

bindings/generated_docstrings/multibody_math.h

@@ -1005,6 +1005,13 @@ Parameter ``translational_tolerance``:
     elements of ``this`` and ``other`` are equal within
     translational_tolerance.)""";
         } IsNearlyEqualWithinAbsoluteTolerance;
+        // Symbol: drake::multibody::SpatialVector::NaN
+        struct /* NaN */ {
+          // Source: drake/multibody/math/spatial_vector.h
+          const char* doc =
+R"""(Factory to create a *NaN* spatial vector, i.e., a SpatialVector whose
+rotational and translational components are all NaN.)""";
+        } NaN;
         // Symbol: drake::multibody::SpatialVector::SetNaN
         struct /* SetNaN */ {
           // Source: drake/multibody/math/spatial_vector.h

bindings/generated_docstrings/multibody_plant.h

@@ -186,32 +186,6 @@ This method must be called pre-Finalize.
 Raises:
     RuntimeError if ``plant`` is finalized or if time_step is changed.)""";
       } ApplyMultibodyPlantConfig;
-      // Symbol: drake::multibody::BaseBodyJointType
-      struct /* BaseBodyJointType */ {
-        // Source: drake/multibody/plant/multibody_plant.h
-        const char* doc =
-R"""(The kind of joint to be used to connect base bodies to world at
-Finalize(). See mbp_working_with_free_bodies "Working with free
-bodies" for definitions and discussion.
-
-See also:
-    SetBaseBodyJointType() for details.)""";
-        // Symbol: drake::multibody::BaseBodyJointType::kQuaternionFloatingJoint
-        struct /* kQuaternionFloatingJoint */ {
-          // Source: drake/multibody/plant/multibody_plant.h
-          const char* doc = R"""(6 dofs, unrestricted orientation.)""";
-        } kQuaternionFloatingJoint;
-        // Symbol: drake::multibody::BaseBodyJointType::kRpyFloatingJoint
-        struct /* kRpyFloatingJoint */ {
-          // Source: drake/multibody/plant/multibody_plant.h
-          const char* doc = R"""(6 dofs using 3 angles; has singularity.)""";
-        } kRpyFloatingJoint;
-        // Symbol: drake::multibody::BaseBodyJointType::kWeldJoint
-        struct /* kWeldJoint */ {
-          // Source: drake/multibody/plant/multibody_plant.h
-          const char* doc = R"""(0 dofs, fixed to World.)""";
-        } kWeldJoint;
-      } BaseBodyJointType;
       // Symbol: drake::multibody::CalcContactFrictionFromSurfaceProperties
       struct /* CalcContactFrictionFromSurfaceProperties */ {
         // Source: drake/multibody/plant/coulomb_friction.h
@@ -4968,7 +4942,7 @@ be used by Finalize(); post-finalize it returns the joint type that
 *was* used if there were any base bodies in need of a joint.
 
 See also:
-    SetBaseBodyJointType())""";
+    SetBaseBodyJointType(), Finalize())""";
         } GetBaseBodyJointType;
         // Symbol: drake::multibody::MultibodyPlant::GetBodiesKinematicallyAffectedBy
         struct /* GetBodiesKinematicallyAffectedBy */ {
@@ -6625,7 +6599,10 @@ Parameter ``model_instance``:
     is to be applied.
 
 Raises:
-    RuntimeError if called after Finalize().)""";
+    RuntimeError if called after Finalize().
+
+See also:
+    GetBaseBodyJointType(), Finalize())""";
         } SetBaseBodyJointType;
         // Symbol: drake::multibody::MultibodyPlant::SetConstraintActiveStatus
         struct /* SetConstraintActiveStatus */ {

bindings/generated_docstrings/multibody_tree.h

@@ -1775,17 +1775,6 @@ PYBIND11_MODULE(plant, m) {
         .value("kLagged", Class::kLagged, cls_doc.kLagged.doc);
   }
 
-  {
-    using Class = BaseBodyJointType;
-    constexpr auto& cls_doc = doc.BaseBodyJointType;
-    py::enum_<Class> cls(m, "BaseBodyJointType", cls_doc.doc);
-    cls.value("kQuaternionFloatingJoint", Class::kQuaternionFloatingJoint,
-           cls_doc.kQuaternionFloatingJoint.doc)
-        .value("kRpyFloatingJoint", Class::kRpyFloatingJoint,
-            cls_doc.kRpyFloatingJoint.doc)
-        .value("kWeldJoint", Class::kWeldJoint, cls_doc.kWeldJoint.doc);
-  }
-
   {
     using Class = MultibodyPlantConfig;
     constexpr auto& cls_doc = doc.MultibodyPlantConfig;

bindings/pydrake/multibody/plant_py.cc

@@ -59,7 +59,6 @@
     AddMultibodyPlant,
     AddMultibodyPlantSceneGraph,
     ApplyMultibodyPlantConfig,
-    BaseBodyJointType,
     CalcContactFrictionFromSurfaceProperties,
     ConnectContactResultsToDrakeVisualizer,
     ContactModel,
@@ -81,6 +80,7 @@
 )
 from pydrake.multibody.tree import (
     BallRpyJoint_,
+    BaseBodyJointType,
     Body_,  # dispreferred alias for RigidBody_
     BodyIndex,
     CalcSpatialInertia,

bindings/pydrake/multibody/test/plant_test.py

@@ -148,6 +148,17 @@ void DoScalarIndependentDefinitions(py::module m) {
         .value("kV", Enum::kV, enum_doc.kV.doc);
   }
 
+  {
+    using Enum = BaseBodyJointType;
+    constexpr auto& cls_doc = doc.BaseBodyJointType;
+    py::enum_<Enum> cls(m, "BaseBodyJointType", cls_doc.doc);
+    cls.value("kQuaternionFloatingJoint", Enum::kQuaternionFloatingJoint,
+           cls_doc.kQuaternionFloatingJoint.doc)
+        .value("kRpyFloatingJoint", Enum::kRpyFloatingJoint,
+            cls_doc.kRpyFloatingJoint.doc)
+        .value("kWeldJoint", Enum::kWeldJoint, cls_doc.kWeldJoint.doc);
+  }
+
   {
     using Class = ScopedName;
     constexpr auto& cls_doc = doc.ScopedName;

bindings/pydrake/multibody/tree_py.cc

@@ -85,7 +85,7 @@ class DrakeKukaIIwaRobot {
         MakeKukaIiwaModel<T>(false /* finalized model */,
                              gravity /* acceleration of gravity */));
 
-    linkN_ = &tree().world_body();
+    linkN_ = &tree().world_link();
 
     // Get this robot's seven links.
     linkA_ = &tree().GetRigidBodyByName("iiwa_link_1");
@@ -111,7 +111,7 @@ class DrakeKukaIIwaRobot {
 
   /// This method gets the number of rigid bodies in this robot.
   /// @returns the number of rigid bodies in this robot.
-  int get_number_of_rigid_bodies() const { return tree().num_bodies(); }
+  int get_number_of_rigid_bodies() const { return tree().num_links(); }
 
   /// This method calculates kinematic properties of the end-effector (herein
   /// denoted as rigid body G) of a 7-DOF KUKA LBR iiwa robot (14 kg payload).
@@ -145,7 +145,7 @@ class DrakeKukaIIwaRobot {
     const SpatialVelocity<T>& V_NG_N = vc.get_V_WB(linkG_->mobod_index());
 
     // Retrieve end-effector spatial acceleration from acceleration cache.
-    std::vector<SpatialAcceleration<T>> A_WB(tree().num_bodies());
+    std::vector<SpatialAcceleration<T>> A_WB(tree().num_links());
     // TODO(eric.cousineau): For this model, the end effector's BodyIndex
     // matches its MobodIndex, thus we're not really checking the difference
     // between MultibodyPlant and MultibodyTree's ordering.

multibody/benchmarks/kuka_iiwa_robot/drake_kuka_iiwa_robot.h

@@ -91,7 +91,7 @@ KukaIiwaModelBuilder<T>::Build() const {
   // angles and a position vector. Alternately, frame An is regarded as
   // coincident with linkA.
   const Joint<T>* joint{nullptr};
-  const RigidBody<T>& linkN = model->world_body();
+  const RigidBody<T>& linkN = model->world_link();
   joint = &AddRevoluteJointFromSpaceXYZAnglesAndXYZ(
       "iiwa_joint_1", linkN, joint_1_rpy_, joint_1_xyz_, linkA,
       Eigen::Vector3d::UnitZ(), model.get());

multibody/benchmarks/kuka_iiwa_robot/make_kuka_iiwa_model.cc

@@ -291,6 +291,14 @@ class SpatialVector {
   /// rotational and translational components are both zero.
   static SpatialQuantity Zero() { return SpatialQuantity{}.SetZero(); }
 
+  /// Factory to create a _NaN_ spatial vector, i.e., a %SpatialVector whose
+  /// rotational and translational components are all NaN.
+  static SpatialQuantity NaN() {
+    SpatialQuantity quantity;
+    quantity.SetNaN();
+    return quantity;
+  }
+
  private:
   // Helper method to return a mutable reference to the derived spatial
   // quantity.

multibody/math/spatial_vector.h

@@ -110,6 +110,27 @@ TYPED_TEST(SpatialQuantityTest, ZeroFactory) {
   EXPECT_TRUE(V.translational() == Vector3<T>::Zero());
 }
 
+// Construction of a "NaN" spatial vector.
+TYPED_TEST(SpatialQuantityTest, NaNFactory) {
+  typedef typename TestFixture::SpatialQuantityType SpatialQuantity;
+  typedef typename TestFixture::ScalarType T;
+  SpatialQuantity V = SpatialQuantity::NaN();
+  auto is_nan = [](const T& x) -> bool {
+    if constexpr (std::is_same_v<T, Expression>) {
+      return symbolic::is_nan(x);
+    }
+    if constexpr (std::is_same_v<T, AutoDiffXd>) {
+      return std::isnan(x.value());
+    }
+    if constexpr (std::is_same_v<T, double>) {
+      return std::isnan(x);
+    }
+  };
+  for (int i = 0; i < V.size(); ++i) {
+    EXPECT_TRUE(is_nan(V[i]));
+  }
+}
+
 // Tests:
 // - Construction from a Eigen expressions.
 // - SetZero() method.