[pybind] Add MultibodyPlant::CalcRelativeRotationMatrix. (RobotLocomo…

…tion#21426)
RussTedrake · Dec 15, 2024 · 8cea254 · 8cea254
1 parent 5825b8b
commit 8cea254
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/bindings/pydrake/multibody/plant_py.cc b/bindings/pydrake/multibody/plant_py.cc
@@ -715,7 +715,10 @@ void DoScalarDependentDefinitions(py::module m, T) {
             py::arg("context"), py::arg("qdot"), cls_doc.MapQDotToVelocity.doc)
         .def("CalcRelativeTransform", &Class::CalcRelativeTransform,
             py::arg("context"), py::arg("frame_A"), py::arg("frame_B"),
-            cls_doc.CalcRelativeTransform.doc);
+            cls_doc.CalcRelativeTransform.doc)
+        .def("CalcRelativeRotationMatrix", &Class::CalcRelativeRotationMatrix,
+            py::arg("context"), py::arg("frame_A"), py::arg("frame_B"),
+            cls_doc.CalcRelativeRotationMatrix.doc);
     if constexpr (std::is_same_v<T, double>) {
       cls  // BR
           .def("MakeVelocityToQDotMap", &Class::MakeVelocityToQDotMap,

diff --git a/bindings/pydrake/multibody/test/plant_test.py b/bindings/pydrake/multibody/test/plant_test.py
@@ -1142,8 +1142,11 @@ def do_test_multibody_tree_kinematics(self, T, time_step):
         base = plant.GetBodyByName("base")
         base_frame = plant.GetFrameByName("base")
         X_WL = plant.CalcRelativeTransform(
-            context, frame_A=world_frame, frame_B=base_frame)
+            context=context, frame_A=world_frame, frame_B=base_frame)
         self.assertIsInstance(X_WL, RigidTransform)
+        R_WL = plant.CalcRelativeRotationMatrix(
+            context=context, frame_A=world_frame, frame_B=base_frame)
+        self.assertIsInstance(R_WL, RotationMatrix_[T])
         free_bodies = plant.GetFloatingBaseBodies()
         self.assertEqual(len(free_bodies), 1)
         self.assertTrue(base.index() in free_bodies)