Add continuous (SO2) variant of double_pendulum (#111)

* Make double_pendulum's joints unbounded revolute (continuous)

* Add continuous (SO(2)) variant of double_pendulum

* Remove update to deprecated function; inherit from DoublePendulumLoader

* Add unit test

python/example_robot_data/robots_loader.py

@@ -483,6 +483,10 @@ class DoublePendulumLoader(RobotLoader):
     urdf_subpath = "urdf"
 
 
+class DoublePendulumContinuousLoader(DoublePendulumLoader):
+    urdf_filename = "double_pendulum_continuous.urdf"
+
+
 def loadDoublePendulum():
     warnings.warn(_depr_msg('loadDoublePendulum()', 'double_pendulum'), FutureWarning, 2)
     return DoublePendulumLoader().robot
@@ -531,6 +535,7 @@ ROBOTS = {
     'baxter': BaxterLoader,
     'cassie': CassieLoader,
     'double_pendulum': DoublePendulumLoader,
+    'double_pendulum_continuous': DoublePendulumContinuousLoader,
     'hector': HectorLoader,
     'hyq': HyQLoader,
     'icub': ICubLoader,

robots/double_pendulum_description/urdf/double_pendulum_continuous.urdf

+<?xml version="1.0" encoding="utf-8"?>
+<!-- This URDF was automatically created by SolidWorks to URDF Exporter! Originally created by Stephen Brawner (brawner@gmail.com)
+     Commit Version: 1.5.1-0-g916b5db  Build Version: 1.5.7152.31018
+     For more information, please see http://wiki.ros.org/sw_urdf_exporter -->
+<robot
+  name="2dof_planar">
+  <link
+    name="base_link">
+    <inertial>
+      <origin
+        xyz="0.0030299 2.6279E-13 0.02912"
+        rpy="0 0 0" />
+      <mass
+        value="0.10159" />
+      <inertia
+        ixx="2.636E-05"
+        ixy="-1.007E-16"
+        ixz="-2.3835E-06"
+        iyy="1.8042E-05"
+        iyz="-4.6617E-09"
+        izz="1.8795E-05" />
+    </inertial>
+    <visual>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/base_link.stl" />
+      </geometry>
+      <material
+        name="">
+        <color
+          rgba="0.96078 1 0 1" />
+      </material>
+    </visual>
+    <collision>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/base_link.stl" />
+      </geometry>
+    </collision>
+  </link>
+  <link
+    name="link1">
+    <inertial>
+      <origin
+        xyz="0.0086107 2.1727E-06 0.036012"
+        rpy="0 0 0" />
+      <mass
+        value="0.26703" />
+      <inertia
+        ixx="0.00040827"
+        ixy="1.2675E-09"
+        ixz="1.8738E-05"
+        iyy="0.00038791"
+        iyz="3.5443E-08"
+        izz="3.6421E-05" />
+    </inertial>
+    <visual>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/link1.stl" />
+      </geometry>
+      <material
+        name="">
+        <color
+          rgba="0.64706 0.61961 0.58824 1" />
+      </material>
+    </visual>
+    <collision>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/link1.stl" />
+      </geometry>
+    </collision>
+  </link>
+  <joint
+    name="joint1"
+    type="continuous">
+    <origin
+      xyz="0.0060872 0 0.035"
+      rpy="0 0 0" />
+    <parent
+      link="base_link" />
+    <child
+      link="link1" />
+    <axis
+      xyz="1 0 0" />
+    <limit
+      lower="0"
+      upper="0"
+      effort="0"
+      velocity="0" />
+    <dynamics
+      damping="0.05" />
+  </joint>
+  <link
+    name="link2">
+    <inertial>
+      <origin
+        xyz="-0.0050107 1.9371E-10 0.10088"
+        rpy="0 0 0" />
+      <mass
+        value="0.33238" />
+      <inertia
+        ixx="0.0011753"
+        ixy="-3.854E-13"
+        ixz="-2.9304E-08"
+        iyy="0.0011666"
+        iyz="-5.2365E-12"
+        izz="1.4553E-05" />
+    </inertial>
+    <visual>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/link2.stl" />
+      </geometry>
+      <material
+        name="">
+        <color
+          rgba="0.64706 0.61961 0.58824 1" />
+      </material>
+    </visual>
+    <collision>
+      <origin
+        xyz="0 0 0"
+        rpy="0 0 0" />
+      <geometry>
+        <mesh
+          filename="package://example-robot-data/robots/double_pendulum_description/meshes/link2.stl" />
+      </geometry>
+    </collision>
+  </link>
+  <joint
+    name="joint2"
+    type="continuous">
+    <origin
+      xyz="0.023 0 0.1"
+      rpy="0 0 0" />
+    <parent
+      link="link1" />
+    <child
+      link="link2" />
+    <axis
+      xyz="1 0 0" />
+    <limit
+      lower="0"
+      upper="0"
+      effort="0"
+      velocity="0" />
+    <dynamics
+      damping="0.05" />
+  </joint>
+</robot>

unittest/test_load.py

@@ -53,6 +53,9 @@ class RobotTestCase(unittest.TestCase):
     def test_double_pendulum(self):
         self.check('double_pendulum', 2, 2)
 
+    def test_double_pendulum_continuous(self):
+        self.check('double_pendulum_continuous', 4, 2)
+
     def test_hector(self):
         self.check('hector', 7, 6)