[bindings] Fix bindings for getFrameVelocity

bindings/python/algorithm/expose-frames.cpp

@@ -68,6 +68,8 @@ namespace pinocchio
       return get_frame_jacobian_time_variation_proxy(model, data, frame_id, rf);
     }
     
+    BOOST_PYTHON_FUNCTION_OVERLOADS(getFrameVelocity_overload, (&getFrameVelocity<double,0,JointCollectionDefaultTpl>), 3, 4)
+
     void exposeFramesAlgo()
     {
       using namespace Eigen;
@@ -86,9 +88,10 @@ namespace pinocchio
 
       bp::def("getFrameVelocity",
               &getFrameVelocity<double,0,JointCollectionDefaultTpl>,
-              bp::args("model","data","frame_id"),
-              "Returns the spatial velocity of the frame expressed in the coordinates system of the Frame itself.\n"
-              "forwardKinematics(model,data,q,v,[a]).");
+              getFrameVelocity_overload(
+                bp::args("model","data","frame_id","reference_frame"),
+                "Returns the spatial velocity of the frame expressed in the coordinate system given by reference_frame.\n"
+                "forwardKinematics(model,data,q,v[,a]) should be called first to compute the joint spatial velocity stored in data.v"));
 
       bp::def("getFrameAcceleration",
               &getFrameAcceleration<double,0,JointCollectionDefaultTpl>,

unittest/python/bindings_frame.py

@@ -2,7 +2,9 @@ import unittest
 import pinocchio as pin
 import numpy as np
 
-class TestFrameBindings(unittest.TestCase):
+from test_case import PinocchioTestCase
+
+class TestFrameBindings(PinocchioTestCase):
 
     def setUp(self):
         self.model = pin.buildSampleModelHumanoidRandom()
@@ -42,5 +44,24 @@ class TestFrameBindings(unittest.TestCase):
         f.placement = new_placement
         self.assertTrue(np.allclose(f.placement.homogeneous, new_placement.homogeneous))
 
+    def test_getters(self):
+        data = self.model.createData()
+        q = pin.randomConfiguration(self.model)
+        v = np.random.rand(self.model.nv)
+        a = np.random.rand(self.model.nv)
+        pin.forwardKinematics(self.model, data, q, v, a)
+
+        T = pin.updateFramePlacement(self.model, data, self.frame_idx)
+        self.assertApprox(T, data.oMi[self.parent_idx].act(self.frame_placement))
+
+        v = pin.getFrameVelocity(self.model, data, self.frame_idx)
+        self.assertApprox(v, self.frame_placement.actInv(data.v[self.parent_idx]))
+        v = pin.getFrameVelocity(self.model, data, self.frame_idx, pin.ReferenceFrame.LOCAL)
+        self.assertApprox(v, self.frame_placement.actInv(data.v[self.parent_idx]))
+        v = pin.getFrameVelocity(self.model, data, self.frame_idx, pin.ReferenceFrame.WORLD)
+        self.assertApprox(v, data.oMi[self.parent_idx].act(data.v[self.parent_idx]))
+        v = pin.getFrameVelocity(self.model, data, self.frame_idx, pin.ReferenceFrame.LOCAL_WORLD_ALIGNED)
+        self.assertApprox(v, pin.SE3(T.rotation, np.zeros(3)).act(self.frame_placement.actInv(data.v[self.parent_idx])))
+
 if __name__ == '__main__':
     unittest.main()