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| | RobotDynamics::Urdf::hydro::BodyHydroData::BodyHydroData () |
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| bool | RobotDynamics::Urdf::hydro::parseHydrodynamicsParameters (const char *model_xml_string, std::map< std::string, hydro::BodyHydroData > &data, bool verbose=false) |
| | Parses an urdf and stores hydrodynamic data for each body in the data argument. More...
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| bool | RobotDynamics::Urdf::urdfReadFromFile (const std::string &filename, ModelPtr model, JointType floating_base_rotation_joint_type=JointTypeSpherical, bool verbose=false) |
| | Read urdf from file path. More...
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| bool | RobotDynamics::Urdf::urdfReadFromString (const std::string &model_xml_string, ModelPtr model, JointType floating_base_rotation_joint_type=JointTypeSpherical, bool verbose=false) |
| | Read urdf from string contents. More...
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| bool | RobotDynamics::Urdf::parseJointBodyNameMapFromString (const std::string &model_xml_string, std::map< std::string, std::string > &jointBodyMap) |
| | This will build a map of joint name to body name. More...
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| bool | RobotDynamics::Urdf::parseJointAndBodyNamesFromString (const std::string &model_xml_string, std::vector< std::string > &joint_names, std::vector< std::string > &body_names) |
| | This will build vectors of joint name and body name pairs. More...
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| bool | RobotDynamics::Urdf::parseJointBodyNameMapFromFile (const std::string &filename, std::map< std::string, std::string > &jointBodyMap) |
| | This will build a map of joint name to body name. More...
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| bool | RobotDynamics::Urdf::parseJointAndQIndex (const RobotDynamics::Model &model, const std::vector< std::string > &body_names, std::vector< unsigned int > &q_indices) |
| | This will build a vector of joint indices in the same order as the list of joints. More...
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| bool | RobotDynamics::Urdf::parseJointAndQIndex (const std::string &model_xml_string, std::vector< unsigned int > &q_indices) |
| | This will build a vector of joint indices in the same order as the list of joints. More...
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The urdfreader has been updated to include parsing of hydrodynamics parameters from an urdf to produce a model with the appropriate hydrodynamic parameters for calculating the dynamics equations including hydrodynamic effects.
For each body that you want to have hydrodynamic effects, you will need to place the following block in the links <link> block,
<hydro>
<drag>
<linear_damping>-1. -2. -3. -4. -5. -6.</linear_damping>
<quadratic_damping>-1. -2. -3. -4. -5. -6.</quadratic_damping>
</drag>
<buoyancy>
<volume>0.1</volume>
<origin xyz= "0.1101 0.121 -0.013"/>
</buoyancy>
<added_mass>
1. 0 0 0 0 0
0 183. 0 0 0 0
0 0 184. 0 0 0
0 0 0 2. 0 0
0 0 0 0 44. 0
0 0 0 0 0 45.
</added_mass>
</hydro>
There are essentially 3 blocks inside the hydro tags where all of the information is gathered. Drag is an effect that is assumed to be quadratic in the spatial velocity of each body, i.e. of the form a*v + b*v^2. To model this we require 6 coefficients for the linear term and 6 coefficients for the quadratic term for each body, contained within the <linear_damping> and <quadratic_damping> tags.
For modelling the effects of added_mass, you will need to include each body's added mass matrix in the <added_mass></added_mass> tag. Note that the added mass matrix is a 6x6 inertia type matrix that should be positive definite.
Buoyancy is the simplest of the three hydro effects modelled and simply requires a volume(in cubic meters) and the x, y, and z coordinates of the center of buoyancy for the body.
- Note
- The drag coefficients need to be negative!
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Any of these effects can be ignored by removing the respective block from the hydro block.
◆ BodyHydroData()
| RobotDynamics::Urdf::hydro::BodyHydroData::BodyHydroData |
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inline |
◆ parseHydrodynamicsParameters()
| bool RobotDynamics::Urdf::hydro::parseHydrodynamicsParameters |
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const char * |
model_xml_string, |
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std::map< std::string, hydro::BodyHydroData > & |
data, |
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bool |
verbose = false |
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) |
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Parses an urdf and stores hydrodynamic data for each body in the data argument.
- Parameters
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| model_xml_string | Urdf contents |
| data | Map of structs to hold the hydro data for each body |
| verbose | True for a whole bunch of debug data to be printed to console |
- Returns
- True if success, false otherwise
Flip the order bc in RDL everything is angular part first
RDL does everything with angular first, so these have to be flipped assuming they're put in the urdf in the order x y z r p y
RDL does everything with angular first, so these have to be flipped assuming they're put in the urdf in the order x y z r p y
◆ parseJointAndBodyNamesFromString()
| bool RobotDynamics::Urdf::parseJointAndBodyNamesFromString |
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const std::string & |
model_xml_string, |
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std::vector< std::string > & |
joint_names, |
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std::vector< std::string > & |
body_names |
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This will build vectors of joint name and body name pairs.
- Parameters
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| model_xml_string | Urdf file contents |
| joint_names | Modified |
| body_names | Modified |
- Returns
- True if succuss, false otherwise
- Warning
- This will NOT give any information about a floating body/joint. The floating body will be ignored since it's not moved by a joint called out in the urdf. Only joints/bodies in 'joint'/'link' tags will be used to populate the map. Non fixed joint/body pairs will be ignored
◆ parseJointAndQIndex() [1/2]
| bool RobotDynamics::Urdf::parseJointAndQIndex |
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const RobotDynamics::Model & |
model, |
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const std::vector< std::string > & |
body_names, |
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std::vector< unsigned int > & |
q_indices |
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This will build a vector of joint indices in the same order as the list of joints.
- Parameters
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| model | RDL Model |
| body_names | vector of body names. Order is important here. Recommended this comes from one of the parse joint and body names functions to ensure correct ordering |
| q_indices | Modified. Vector of q indices populated |
- Returns
- true on success, false otherwise
- Warning
- This will NOT give any information about a floating body/joint
◆ parseJointAndQIndex() [2/2]
| bool RobotDynamics::Urdf::parseJointAndQIndex |
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const std::string & |
model_xml_string, |
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std::vector< unsigned int > & |
q_indices |
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) |
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This will build a vector of joint indices in the same order as the list of joints.
- Parameters
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| model_xml_string | Urdf string |
| q_indices | Modified. Vector of q indices populated |
- Returns
- true on success, false otherwise
- Warning
- This will NOT give any information about a floating body/joint
◆ parseJointBodyNameMapFromFile()
| bool RobotDynamics::Urdf::parseJointBodyNameMapFromFile |
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const std::string & |
filename, |
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std::map< std::string, std::string > & |
jointBodyMap |
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) |
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This will build a map of joint name to body name.
- Parameters
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| filename | Filepath |
| jointBodyMap | Modified |
- Returns
- Warning
- This will NOT give any information about a floating body/joint. The floating body will be ignored since it's not moved by a joint called out in the urdf. Only joints/bodies in 'joint'/'link' tags will be used to populate the map.
◆ parseJointBodyNameMapFromString()
| bool RobotDynamics::Urdf::parseJointBodyNameMapFromString |
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const std::string & |
model_xml_string, |
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std::map< std::string, std::string > & |
jointBodyMap |
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) |
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This will build a map of joint name to body name.
- Parameters
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| model_xml_string | Urdf file contents |
| jointBodyMap | Modified |
- Returns
- Warning
- This will NOT give any information about a floating body/joint. The floating body will be ignored since it's not moved by a joint called out in the urdf. Only joints/bodies in 'joint'/'link' tags will be used to populate the map.
◆ urdfReadFromFile()
| bool RobotDynamics::Urdf::urdfReadFromFile |
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const std::string & |
filename, |
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ModelPtr |
model, |
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JointType |
floating_base_rotation_joint_type = JointTypeSpherical, |
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bool |
verbose = false |
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) |
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Read urdf from file path.
- Parameters
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| filename | |
| model | |
| verbose | if true will print model information |
- Returns
- True on success, false otherwise
- Note
- This function will deduce whether or not the robot has a floating base by checking the name of the root link. If the name of the root link is "world", then it will have a floating base.
◆ urdfReadFromString()
| bool RobotDynamics::Urdf::urdfReadFromString |
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const std::string & |
model_xml_string, |
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ModelPtr |
model, |
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JointType |
floating_base_rotation_joint_type = JointTypeSpherical, |
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bool |
verbose = false |
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) |
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Read urdf from string contents.
- Parameters
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| model_xml_string | |
| model | |
| verbose | if true will print model information |
- Returns
- True on success, false otherwise
- Note
- This function will deduce whether or not the robot has a floating base by checking the name of the root link. If the name of the root link is "world", then it will have a floating base.
◆ addedMassMatrix
For added mass inertial effects
◆ centerOfBuoyancy
| Math::Vector3d RobotDynamics::Urdf::hydro::BodyHydroData::centerOfBuoyancy |
Coordinates of the center of buoyancy in body frame
◆ dragCoefficient
| double RobotDynamics::Urdf::hydro::BodyHydroData::dragCoefficient |
Coefficient of drag for the body
◆ ellipsoidMajorAxisDirection
| Math::Vector3d RobotDynamics::Urdf::hydro::BodyHydroData::ellipsoidMajorAxisDirection |
◆ hasHydro
| bool RobotDynamics::Urdf::hydro::BodyHydroData::hasHydro |
True if the hydro block exists in a body's link block
◆ linearDrag
| std::vector<double> RobotDynamics::Urdf::hydro::BodyHydroData::linearDrag |
6 directional elements for the linear drag term
◆ quadraticDrag
| std::vector<double> RobotDynamics::Urdf::hydro::BodyHydroData::quadraticDrag |
6 directional elements for the quadratic drag term
◆ volume
| double RobotDynamics::Urdf::hydro::BodyHydroData::volume |
Body volume in cubic meters
