[pydrake] Bind Joint.kTypeName constants (#21896)

RobotLocomotion · Sep 12, 2024 · b28b5dc · b28b5dc
1 parent 59a15c3
commit b28b5dc
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Showing 3 changed files with 26 additions and 3 deletions.
diff --git a/bindings/pydrake/examples/gym/envs/cart_pole.py b/bindings/pydrake/examples/gym/envs/cart_pole.py
@@ -30,6 +30,10 @@
     MultibodyPlant,
     MultibodyPlantConfig,
 )
+from pydrake.multibody.tree import (
+    PrismaticJoint,
+    RevoluteJoint,
+)
 from pydrake.systems.analysis import Simulator
 from pydrake.systems.drawing import plot_graphviz, plot_system_graphviz
 from pydrake.systems.framework import (
@@ -338,14 +342,14 @@ def reset_handler(simulator, diagram_context, seed):
     # Ensure the positions are within the joint limits.
     for pair in home_positions:
         joint = plant.GetJointByName(pair[0])
-        if joint.type_name() == "revolute":
+        if joint.type_name() == RevoluteJoint.kTypeName:
             joint.set_angle(plant_context,
                             np.clip(pair[1],
                                     joint.position_lower_limit(),
                                     joint.position_upper_limit()
                                     )
                             )
-        if joint.type_name() == "prismatic":
+        if joint.type_name() == PrismaticJoint.kTypeName:
             joint.set_translation(plant_context,
                                   np.clip(pair[1],
                                           joint.position_lower_limit(),
@@ -354,7 +358,7 @@ def reset_handler(simulator, diagram_context, seed):
                                   )
     for pair in home_velocities:
         joint = plant.GetJointByName(pair[0])
-        if joint.type_name() == "revolute":
+        if joint.type_name() == RevoluteJoint.kTypeName:
             joint.set_angular_rate(plant_context,
                                    np.clip(pair[1],
                                            joint.velocity_lower_limit(),

diff --git a/bindings/pydrake/multibody/test/plant_test.py b/bindings/pydrake/multibody/test/plant_test.py
@@ -654,6 +654,7 @@ def _test_joint_api(self, T, joint):
         self._test_multibody_tree_element_mixin(T, joint)
         self.assertIsInstance(joint.name(), str)
         self.assertIsInstance(joint.type_name(), str)
+        self.assertEqual(joint.type_name(), joint.kTypeName)
         self.assertIsInstance(joint.parent_body(), Body)
         self.assertIsInstance(joint.child_body(), Body)
         self.assertIsInstance(joint.frame_on_parent(), Frame)

diff --git a/bindings/pydrake/multibody/tree_py.cc b/bindings/pydrake/multibody/tree_py.cc
@@ -492,6 +492,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "BallRpyJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(
             py::init<const string&, const Frame<T>&, const Frame<T>&, double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -523,6 +525,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "PlanarJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&,
                  Vector3<double>>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -572,6 +576,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "PrismaticJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&,
                  const Vector3<double>&, double, double, double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -628,6 +634,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "QuaternionFloatingJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&, double,
                  double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -688,6 +696,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "RevoluteJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&,
                  const Vector3<double>&, double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -744,6 +754,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "RpyFloatingJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&, double,
                  double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -801,6 +813,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "ScrewJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&, double,
                  double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -854,6 +868,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "UniversalJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(
             py::init<const string&, const Frame<T>&, const Frame<T>&, double>(),
             py::arg("name"), py::arg("frame_on_parent"),
@@ -884,6 +900,8 @@ void DoScalarDependentDefinitions(py::module m, T) {
     auto cls = DefineTemplateClassWithDefault<Class, Joint<T>>(
         m, "WeldJoint", param, cls_doc.doc);
     cls  // BR
+        .def_property_readonly_static(
+            "kTypeName", [](py::object /* self */) { return Class::kTypeName; })
         .def(py::init<const string&, const Frame<T>&, const Frame<T>&,
                  const RigidTransform<double>&>(),
             py::arg("name"), py::arg("frame_on_parent_F"),