Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
kinematic_constraints::VisibilityConstraint Class Reference

Class for constraints on the visibility relationship between a sensor and a target. More...

#include <kinematic_constraint.h>

Inheritance diagram for kinematic_constraints::VisibilityConstraint:
Inheritance graph
[legend]

Public Member Functions

virtual void clear ()
 Clear the stored constraint. More...
 
bool configure (const moveit_msgs::VisibilityConstraint &vc, const robot_state::Transforms &tf)
 Configure the constraint based on a moveit_msgs::VisibilityConstraint. More...
 
virtual ConstraintEvaluationResult decide (const robot_state::RobotState &state, bool verbose=false) const
 Decide whether the constraint is satisfied in the indicated state. More...
 
virtual bool enabled () const
 This function returns true if this constraint is configured and able to decide whether states do meet the constraint or not. If this function returns false it means that decide() will always return true – there is no constraint to be checked. More...
 
virtual bool equal (const KinematicConstraint &other, double margin) const
 Check if two constraints are the same. More...
 
void getMarkers (const robot_state::RobotState &state, visualization_msgs::MarkerArray &markers) const
 Adds markers associated with the visibility cone, sensor and target to the visualization array. More...
 
shapes::MeshgetVisibilityCone (const robot_state::RobotState &state) const
 Gets a trimesh shape representing the visibility cone. More...
 
virtual void print (std::ostream &out=std::cout) const
 Print the constraint data. More...
 
 VisibilityConstraint (const robot_model::RobotModelConstPtr &model)
 Constructor. More...
 
- Public Member Functions inherited from kinematic_constraints::KinematicConstraint
double getConstraintWeight () const
 The weight of a constraint is a multiplicative factor associated to the distance computed by the decide() function. More...
 
const robot_model::RobotModelConstPtr & getRobotModel () const
 
ConstraintType getType () const
 Get the type of constraint. More...
 
 KinematicConstraint (const robot_model::RobotModelConstPtr &model)
 Constructor. More...
 
virtual ~KinematicConstraint ()
 

Protected Member Functions

bool decideContact (const collision_detection::Contact &contact) const
 Function that gets passed into collision checking to allow some collisions. More...
 

Protected Attributes

collision_detection::CollisionRobotPtr collision_robot_
 A copy of the collision robot maintained for collision checking the cone against robot links. More...
 
unsigned int cone_sides_
 Storage for the cone sides. More...
 
double max_range_angle_
 Storage for the max range angle. More...
 
double max_view_angle_
 Storage for the max view angle. More...
 
bool mobile_sensor_frame_
 True if the sensor is a non-fixed frame relative to the transform frame. More...
 
bool mobile_target_frame_
 True if the target is a non-fixed frame relative to the transform frame. More...
 
EigenSTL::vector_Vector3d points_
 A set of points along the base of the circle. More...
 
std::string sensor_frame_id_
 The sensor frame id. More...
 
Eigen::Affine3d sensor_pose_
 The sensor pose transformed into the transform frame. More...
 
int sensor_view_direction_
 Storage for the sensor view direction. More...
 
std::string target_frame_id_
 The target frame id. More...
 
Eigen::Affine3d target_pose_
 The target pose transformed into the transform frame. More...
 
double target_radius_
 Storage for the target radius. More...
 
- Protected Attributes inherited from kinematic_constraints::KinematicConstraint
double constraint_weight_
 The weight of a constraint is a multiplicative factor associated to the distance computed by the decide() function. More...
 
robot_model::RobotModelConstPtr robot_model_
 The kinematic model associated with this constraint. More...
 
ConstraintType type_
 The type of the constraint. More...
 

Additional Inherited Members

- Public Types inherited from kinematic_constraints::KinematicConstraint
enum  ConstraintType {
  UNKNOWN_CONSTRAINT, JOINT_CONSTRAINT, POSITION_CONSTRAINT, ORIENTATION_CONSTRAINT,
  VISIBILITY_CONSTRAINT
}
 Enum for representing a constraint. More...
 

Detailed Description

Class for constraints on the visibility relationship between a sensor and a target.

Visibility constraints are the most complicated kinematic constraint type. They are designed to test whether a visibility relationship is maintained in a given state. For the visibility relationship to be maintained, a sensor must have an unimpeded view of a target - this is useful, for instance, if one wants to test whether a robot can see its hand with a given sensor in a given state. The mechanism that is used to test the constraint is a combination of geometric checks, and then a collision check that tests whether a cone that connects the sensor and the target is entirely unobstructed by the robot's links.

The constraint consists of a sensor pose, a target pose, a few parameters that govern the shape of the target, and a few parameters that allow finer control over the geometry of the check. There are two general ways that this constraint can be used. The first way to leave max_view_angle and max_range_angle in the VisibilityConstraint message as 0.0. In this case, the only check that is performed is the collision check against the cone. This check assumes that the sensor can see in all directions - the orientation of the sensor has no effect on the creation of the cone. It is important to note that the sensor and the target poses must not result in collision - if they are associated with sensor frames or robot links they must be specified to be outside the robot's body or all states will violate the Visibility Constraint. For an example of a visualization of a visibility constraint (produced using the getMarkers member function), see this image:

fingertip_cone.png
Visibility constraint satisfied as cone volume is clear

The cone is shown in red, and the arrows show normals. This visibility constraint uses a sensor pose (the narrow end of the cone ) of the PR2's narrow_stereo_optical_frame, except shifted along the Z axis such that the pose is outside of the robot's head and doesn't collide. The cone is allowed to collide with the actual sensor associated with the header frame, just not with any other links. The target pose is a 5 cm circle offset from the l_gripper_r_finger_tip_link, again so as not to collide - again, the cone can collide with the target link, but now with any other links. In the indicated state the cone is collision free and thus satisfies the collision component of the visibility constraint. In this image, however, the right arm intersects the cone, violating the visibility constraint:

fingertip_collision.png
Visibility constraint violated as right arm is within the cone

Note that both the target and the sensor frame can change with the robot's state.

The collision check essentially asks whether or not the volume between the sensor pose and the target pose are clear, but that's only one aspect of visibility we may care about. The visibility constraint also allows for some geometric reasoning about the relationship between the sensor or the target - this allows information such as approximate field of view of the sensor to be factored into the constraint. To use this reasoning, the sensor_view_direction of the field should first be set - this specifies which axis of the sensor pose frame is actually pointing. The system assumes that the the sensor pose has been set up such that a single of the axes is pointing directly out of the sensor. Once this value is set correctly, one or both of the max_view_angle and the max_range_angle values can be set. Setting a positive max_view_angle will constrain the sensor along the specified axis and the target along its Z axis to be pointing at each other. Practically speaking, this ensures that the sensor has sufficient visibility to the front of the target - if the target is pointing the opposite direction, or is too steeply perpindicular to the target, then the max_view_angle part of the constraint will be violated. The getMarkers function can again help explain this - the view angle is the angular difference between the blue arrow associated with the sensor and the red arrow associated with the target.

exact_opposites.png
Max view angle is evaluated at 0.0
fourty_five.png
Max view angle evaluates around pi/4
perpindicular.png
Max view angle evaluates at pi/2, the maximum
other_side.png
Sensor pointed at wrong side of target, will violate constraint as long as max_view_angle

0.0"

If constraining the target to be within the field of view of the sensor is the goal, then the max_range_angle can be set. The range angle is calculated as the angle between the origins of the sensor and the target frame - the orientations are unimportant. In the above images, the range angle is always 0, as the target's center is directly lined up with the blue arrow. In this image, however, the view angle is evaluated at 0.0, while the range angle is evaluated at .65.

range_angle.png
Range angle is high, so only sensors with wide fields of view would see the target

By limiting the max_range_angle, you can constrain the target to be within the field of view of the sensor. Max_view_angle and max_range_angle can be used at once.

Definition at line 750 of file kinematic_constraint.h.

Constructor & Destructor Documentation

kinematic_constraints::VisibilityConstraint::VisibilityConstraint ( const robot_model::RobotModelConstPtr &  model)

Constructor.

Parameters
[in]modelThe kinematic model used for constraint evaluation

Definition at line 643 of file kinematic_constraint.cpp.

Member Function Documentation

void kinematic_constraints::VisibilityConstraint::clear ( )
virtual

Clear the stored constraint.

Implements kinematic_constraints::KinematicConstraint.

Definition at line 649 of file kinematic_constraint.cpp.

bool kinematic_constraints::VisibilityConstraint::configure ( const moveit_msgs::VisibilityConstraint &  vc,
const robot_state::Transforms tf 
)

Configure the constraint based on a moveit_msgs::VisibilityConstraint.

For the configure command to be successful, the target radius must be non-zero (negative values will have the absolute value taken). If cone sides are less than 3, a value of 3 will be used.

Parameters
[in]vcmoveit_msgs::VisibilityConstraint for configuration
Returns
True if constraint can be configured from vc

Definition at line 665 of file kinematic_constraint.cpp.

kinematic_constraints::ConstraintEvaluationResult kinematic_constraints::VisibilityConstraint::decide ( const robot_state::RobotState state,
bool  verbose = false 
) const
virtual

Decide whether the constraint is satisfied in the indicated state.

Parameters
[in]stateThe kinematic state used for evaluation
[in]verboseWhether or not to print output
Returns

Implements kinematic_constraints::KinematicConstraint.

Definition at line 920 of file kinematic_constraint.cpp.

bool kinematic_constraints::VisibilityConstraint::decideContact ( const collision_detection::Contact contact) const
protected

Function that gets passed into collision checking to allow some collisions.

The cone object is allowed to touch either the sensor or the header frame, but not anything else

Parameters
[in]contactThe contact in question
Returns
True if the collision is allowed, otherwise false

Definition at line 1007 of file kinematic_constraint.cpp.

bool kinematic_constraints::VisibilityConstraint::enabled ( ) const
virtual

This function returns true if this constraint is configured and able to decide whether states do meet the constraint or not. If this function returns false it means that decide() will always return true – there is no constraint to be checked.

Implements kinematic_constraints::KinematicConstraint.

Definition at line 768 of file kinematic_constraint.cpp.

bool kinematic_constraints::VisibilityConstraint::equal ( const KinematicConstraint other,
double  margin 
) const
virtual

Check if two constraints are the same.

For visibility constraints this means that:

  • The types are the same,
  • The target frame ids are the same
  • The sensor frame ids are the same
  • The cone sides number is the same
  • The sensor view directions are the same
  • The max view angles and target radii are within the margin
  • The sensor and target poses are within the margin, as computed by taking the norm of the difference.
Parameters
[in]otherThe other constraint to test
[in]marginThe margin to apply to all values associated with constraint
Returns
True if equal, otherwise false

Implements kinematic_constraints::KinematicConstraint.

Definition at line 741 of file kinematic_constraint.cpp.

void kinematic_constraints::VisibilityConstraint::getMarkers ( const robot_state::RobotState state,
visualization_msgs::MarkerArray &  markers 
) const

Adds markers associated with the visibility cone, sensor and target to the visualization array.

The visibility cone and two arrows - a blue array that issues from the sensor_view_direction of the sensor, and a red arrow the issues along the Z axis of the the target frame.

Parameters
[in]stateThe state from which to produce the markers
[out]markersThe marker array to which the markers will be added

Definition at line 847 of file kinematic_constraint.cpp.

shapes::Mesh * kinematic_constraints::VisibilityConstraint::getVisibilityCone ( const robot_state::RobotState state) const

Gets a trimesh shape representing the visibility cone.

Parameters
[in]stateThe state from which to produce the cone
Returns
The shape associated with the cone

Definition at line 773 of file kinematic_constraint.cpp.

void kinematic_constraints::VisibilityConstraint::print ( std::ostream &  out = std::cout) const
virtual

Print the constraint data.

Parameters
[in]outThe file descriptor for printing

Reimplemented from kinematic_constraints::KinematicConstraint.

Definition at line 1031 of file kinematic_constraint.cpp.

Member Data Documentation

collision_detection::CollisionRobotPtr kinematic_constraints::VisibilityConstraint::collision_robot_
protected

A copy of the collision robot maintained for collision checking the cone against robot links.

Definition at line 835 of file kinematic_constraint.h.

unsigned int kinematic_constraints::VisibilityConstraint::cone_sides_
protected

Storage for the cone sides.

Definition at line 844 of file kinematic_constraint.h.

double kinematic_constraints::VisibilityConstraint::max_range_angle_
protected

Storage for the max range angle.

Definition at line 848 of file kinematic_constraint.h.

double kinematic_constraints::VisibilityConstraint::max_view_angle_
protected

Storage for the max view angle.

Definition at line 847 of file kinematic_constraint.h.

bool kinematic_constraints::VisibilityConstraint::mobile_sensor_frame_
protected

True if the sensor is a non-fixed frame relative to the transform frame.

Definition at line 837 of file kinematic_constraint.h.

bool kinematic_constraints::VisibilityConstraint::mobile_target_frame_
protected

True if the target is a non-fixed frame relative to the transform frame.

Definition at line 838 of file kinematic_constraint.h.

EigenSTL::vector_Vector3d kinematic_constraints::VisibilityConstraint::points_
protected

A set of points along the base of the circle.

Definition at line 845 of file kinematic_constraint.h.

std::string kinematic_constraints::VisibilityConstraint::sensor_frame_id_
protected

The sensor frame id.

Definition at line 840 of file kinematic_constraint.h.

Eigen::Affine3d kinematic_constraints::VisibilityConstraint::sensor_pose_
protected

The sensor pose transformed into the transform frame.

Definition at line 841 of file kinematic_constraint.h.

int kinematic_constraints::VisibilityConstraint::sensor_view_direction_
protected

Storage for the sensor view direction.

Definition at line 842 of file kinematic_constraint.h.

std::string kinematic_constraints::VisibilityConstraint::target_frame_id_
protected

The target frame id.

Definition at line 839 of file kinematic_constraint.h.

Eigen::Affine3d kinematic_constraints::VisibilityConstraint::target_pose_
protected

The target pose transformed into the transform frame.

Definition at line 843 of file kinematic_constraint.h.

double kinematic_constraints::VisibilityConstraint::target_radius_
protected

Storage for the target radius.

Definition at line 846 of file kinematic_constraint.h.


The documentation for this class was generated from the following files:


moveit_core
Author(s): Ioan Sucan , Sachin Chitta , Acorn Pooley
autogenerated on Mon Jan 15 2018 03:50:45