Fix orientation constraints (moveit#3656)

The tolerance of orientation constraints needs to be interpreted w.r.t. the given frame_id of the constraint instead of the target frame. Not doing so, a large tolerance is interpreted about the wrong axis and resolving constraint frames fails.
Unfortunately, the proposed approach only works for the ROTATION_VECTOR representation.

moveit_core/constraint_samplers/src/default_constraint_samplers.cpp

@@ -497,6 +497,9 @@ bool IKConstraintSampler::samplePose(Eigen::Vector3d& pos, Eigen::Quaterniond& q
              moveit_msgs::OrientationConstraint::ROTATION_VECTOR)
     {
       Eigen::Vector3d rotation_vector(angle_x, angle_y, angle_z);
+      // convert rotation vector from frame_id to target frame
+      rotation_vector =
+          sampling_pose_.orientation_constraint_->getDesiredRotationMatrixInRefFrame().transpose() * rotation_vector;
       diff = Eigen::Isometry3d(Eigen::AngleAxisd(rotation_vector.norm(), rotation_vector.normalized()));
     }
     else
@@ -506,14 +509,9 @@ bool IKConstraintSampler::samplePose(Eigen::Vector3d& pos, Eigen::Quaterniond& q
                              "The parameterization type for the orientation constraints is invalid.");
     }
 
-    // diff is isometry by construction
-    // getDesiredRotationMatrix() returns a valid rotation matrix by contract
-    // reqr has thus to be a valid isometry
-    Eigen::Isometry3d reqr(sampling_pose_.orientation_constraint_->getDesiredRotationMatrix() * diff.linear());
-    quat = Eigen::Quaterniond(reqr.linear());  // reqr is isometry, so quat has to be normalized
+    quat = Eigen::Quaterniond(sampling_pose_.orientation_constraint_->getDesiredRotationMatrix() * diff.linear());
 
-    // if this constraint is with respect a mobile frame, we need to convert this rotation to the root frame of the
-    // model
+    // if this constraint is with respect to a mobile frame, we need to convert this rotation to the root frame of the model
     if (sampling_pose_.orientation_constraint_->mobileReferenceFrame())
     {
       // getFrameTransform() returns a valid isometry by contract

moveit_core/kinematic_constraints/include/moveit/kinematic_constraints/kinematic_constraint.h

@@ -337,12 +337,19 @@ MOVEIT_CLASS_FORWARD(OrientationConstraint);  // Defines OrientationConstraintPt
 /**
  * \brief Class for constraints on the orientation of a link
  *
- * This class expresses an orientation constraint on a particular
- * link.  The constraint is specified in terms of a quaternion, with
- * tolerances on X,Y, and Z axes.  The rotation difference is computed
- * based on the XYZ Euler angle formulation (intrinsic rotations) or as a rotation vector. This depends on the
- * `Parameterization` type. The header on the quaternion can be specified in terms of either a fixed or a mobile
- * frame.  The type value will return ORIENTATION_CONSTRAINT.
+ * This class expresses an orientation constraint on a particular link.
+ * The constraint specifies a target orientation via a quaternion as well as
+ * tolerances on X,Y, and Z rotation axes.
+ * The rotation difference between the target and actual link orientation is expressed
+ * either as XYZ Euler angles or as a rotation vector (depending on the `parameterization` type).
+ * The latter is highly recommended, because it supports resolution of subframes and attached bodies.
+ * Also, rotation vector representation allows to interpret the tolerances always w.r.t. the given reference frame.
+ * Euler angles are much more restricted and exhibit singularities.
+ *
+ * For efficiency, if the target orientation is expressed w.r.t. to a fixed frame (relative to the planning frame),
+ * some stuff is precomputed. However, mobile reference frames are supported as well.
+ *
+ * The type value will return ORIENTATION_CONSTRAINT.
  *
  */
 class OrientationConstraint : public KinematicConstraint
@@ -440,6 +447,19 @@ class OrientationConstraint : public KinematicConstraint
    *
    * The returned matrix is always a valid rotation matrix.
    */
+  const Eigen::Matrix3d& getDesiredRotationMatrixInRefFrame() const
+  {
+    // validity of the rotation matrix is enforced in configure()
+    return desired_R_in_frame_id_;
+  }
+
+  /**
+   * \brief The rotation target in the reference or tf frame.
+   *
+   * @return The target rotation.
+   *
+   * The returned matrix is always a valid rotation matrix.
+   */
   const Eigen::Matrix3d& getDesiredRotationMatrix() const
   {
     // validity of the rotation matrix is enforced in configure()
@@ -485,16 +505,15 @@ class OrientationConstraint : public KinematicConstraint
   }
 
 protected:
-  const moveit::core::LinkModel* link_model_;   /**< \brief The target link model */
-  Eigen::Matrix3d desired_rotation_matrix_;     /**< \brief The desired rotation matrix in the tf frame. Guaranteed to
-                                                 * be valid rotation matrix. */
-  Eigen::Matrix3d desired_rotation_matrix_inv_; /**< \brief The inverse of the desired rotation matrix, precomputed for
-                                                 * efficiency. Guaranteed to be valid rotation matrix. */
-  std::string desired_rotation_frame_id_;       /**< \brief The target frame of the transform tree */
-  bool mobile_frame_;                           /**< \brief Whether or not the header frame is mobile or fixed */
-  int parameterization_type_;                   /**< \brief Parameterization type for orientation tolerance. */
+  const moveit::core::LinkModel* link_model_;   /**< The target link model */
+  Eigen::Matrix3d desired_R_in_frame_id_;       /**< Desired rotation matrix in frame_id */
+  Eigen::Matrix3d desired_rotation_matrix_;     /**< The desired rotation matrix in the tf frame */
+  Eigen::Matrix3d desired_rotation_matrix_inv_; /**< The inverse of desired_rotation_matrix_ (for efficiency) */
+  std::string desired_rotation_frame_id_;       /**< The target frame of the transform tree */
+  bool mobile_frame_;                           /**< Whether or not the header frame is mobile or fixed */
+  int parameterization_type_;                   /**< Parameterization type for orientation tolerance */
   double absolute_x_axis_tolerance_, absolute_y_axis_tolerance_,
-      absolute_z_axis_tolerance_; /**< \brief Storage for the tolerances */
+      absolute_z_axis_tolerance_; /**< Storage for the tolerances */
 };
 
 MOVEIT_CLASS_FORWARD(PositionConstraint);  // Defines PositionConstraintPtr, ConstPtr, WeakPtr... etc

moveit_core/kinematic_constraints/src/kinematic_constraint.cpp

@@ -555,10 +555,11 @@ bool OrientationConstraint::configure(const moveit_msgs::OrientationConstraint&
   // clearing out any old data
   clear();
 
-  link_model_ = robot_model_->getLinkModel(oc.link_name);
+  bool found;
+  link_model_ = robot_model_->getLinkModel(oc.link_name, &found);
   if (!link_model_)
   {
-    ROS_WARN_NAMED("kinematic_constraints", "Could not find link model for link name %s", oc.link_name.c_str());
+    ROS_WARN_NAMED("kinematic_constraints", "Could not find link model for link name '%s'", oc.link_name.c_str());
     return false;
   }
   Eigen::Quaterniond q;
@@ -576,6 +577,7 @@ bool OrientationConstraint::configure(const moveit_msgs::OrientationConstraint&
     ROS_WARN_NAMED("kinematic_constraints", "No frame specified for position constraint on link '%s'!",
                    oc.link_name.c_str());
 
+  desired_R_in_frame_id_ = Eigen::Quaterniond(q);  // desired rotation wrt. frame_id
   if (tf.isFixedFrame(oc.header.frame_id))
   {
     tf.transformQuaternion(oc.header.frame_id, q, q);
@@ -709,10 +711,8 @@ ConstraintEvaluationResult OrientationConstraint::decide(const moveit::core::Rob
   else if (parameterization_type_ == moveit_msgs::OrientationConstraint::ROTATION_VECTOR)
   {
     Eigen::AngleAxisd aa(diff.linear());
-    xyz_rotation = aa.axis() * aa.angle();
-    xyz_rotation(0) = fabs(xyz_rotation(0));
-    xyz_rotation(1) = fabs(xyz_rotation(1));
-    xyz_rotation(2) = fabs(xyz_rotation(2));
+    // transform rotation vector from target frame to frame_id and take absolute values
+    xyz_rotation = (desired_R_in_frame_id_ * (aa.axis() * aa.angle())).cwiseAbs();
   }
   else
   {

moveit_core/kinematic_constraints/src/utils.cpp

@@ -183,6 +183,7 @@ moveit_msgs::Constraints constructGoalConstraints(const std::string& link_name,
 
   goal.orientation_constraints.resize(1);
   moveit_msgs::OrientationConstraint& ocm = goal.orientation_constraints[0];
+  ocm.parameterization = moveit_msgs::OrientationConstraint::ROTATION_VECTOR;
   ocm.link_name = link_name;
   ocm.header = pose.header;
   ocm.orientation = pose.pose.orientation;
@@ -565,9 +566,17 @@ bool resolveConstraintFrames(const moveit::core::RobotState& state, moveit_msgs:
     // the constraint needs to be expressed in the frame of a robot link.
     if (c.link_name != robot_link->getName())
     {
+      if (c.parameterization == moveit_msgs::OrientationConstraint::XYZ_EULER_ANGLES)
+      {
+        ROS_ERROR_NAMED(
+            LOGNAME, "Euler angles parameterization is not supported for non-link frames in orientation constraints. \n"
+                     "Switch to rotation vector parameterization.");
+        return false;
+      }
       c.link_name = robot_link->getName();
       Eigen::Quaterniond link_name_to_robot_link(transform.linear().transpose() *
                                                  state.getGlobalLinkTransform(robot_link).linear());
+      // adapt goal orientation
       Eigen::Quaterniond quat_target;
       tf2::fromMsg(c.orientation, quat_target);
       c.orientation = tf2::toMsg(quat_target * link_name_to_robot_link);

moveit_core/kinematic_constraints/test/test_orientation_constraints.cpp

@@ -450,7 +450,7 @@ TEST_F(FloatingJointRobot, OrientationConstraintsParameterization)
     EXPECT_TRUE(oc_rotvec.decide(robot_state).satisfied);
   }
 
-  // and now some simple test cases where whe change the nominal orientation of the constraints,
+  // and now some simple test cases where we change the nominal orientation of the constraints,
   // instead of changing the orientation of the robot
   robot_state.setToDefaultValues();
   robot_state.update();
@@ -474,6 +474,42 @@ TEST_F(FloatingJointRobot, OrientationConstraintsParameterization)
   EXPECT_FALSE(oc_rotvec.decide(robot_state).satisfied);
 }
 
+TEST_F(FloatingJointRobot, ToleranceInRefFrame)
+{
+  moveit::core::RobotState robot_state(robot_model_);
+  robot_state.setToDefaultValues();
+  auto base = rotation_vector_to_quat(M_PI / 2.0, 0, 0);  // base rotation: 90° about x
+  setRobotEndEffectorOrientation(robot_state, base);
+  robot_state.update();
+
+  moveit::core::Transforms tf(robot_model_->getModelFrame());
+
+  // create message to configure orientation constraints
+  moveit_msgs::OrientationConstraint ocm;
+  ocm.link_name = "ee";
+  ocm.header.frame_id = robot_model_->getModelFrame();
+  ocm.parameterization = moveit_msgs::OrientationConstraint::ROTATION_VECTOR;
+  ocm.orientation = tf2::toMsg(base);
+  ocm.absolute_x_axis_tolerance = 0.2;
+  ocm.absolute_y_axis_tolerance = 0.2;
+  ocm.absolute_z_axis_tolerance = 1.0;
+  ocm.weight = 1.0;
+
+  kinematic_constraints::OrientationConstraint oc(robot_model_);
+  EXPECT_TRUE(oc.configure(ocm, tf));
+
+  EXPECT_TRUE(oc.decide(robot_state).satisfied);  // link and target are perfectly aligned
+
+  // strong rotation w.r.t. base frame is ok
+  auto delta = rotation_vector_to_quat(0.1, 0.1, 0.9);
+  setRobotEndEffectorOrientation(robot_state, delta * base);
+  EXPECT_TRUE(oc.decide(robot_state).satisfied);
+
+  // strong rotation w.r.t. link frame is not ok
+  setRobotEndEffectorOrientation(robot_state, base * delta);
+  EXPECT_FALSE(oc.decide(robot_state).satisfied);  // link and target are perfectly aligned
+}
+
 int main(int argc, char** argv)
 {
   testing::InitGoogleTest(&argc, argv);