graspnetAPI.utils.dexnet.grasping package

Subpackages

Submodules

graspnetAPI.utils.dexnet.grasping.contacts module

Copyright ©2017. The Regents of the University of California (Regents). All Rights Reserved. Permission to use, copy, modify, and distribute this software and its documentation for educational, research, and not-for-profit purposes, without fee and without a signed licensing agreement, is hereby granted, provided that the above copyright notice, this paragraph and the following two paragraphs appear in all copies, modifications, and distributions. Contact The Office of Technology Licensing, UC Berkeley, 2150 Shattuck Avenue, Suite 510, Berkeley, CA 94720-1620, (510) 643- 7201, otl@berkeley.edu, http://ipira.berkeley.edu/industry-info for commercial licensing opportunities.

IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED HEREUNDER IS PROVIDED “AS IS”. REGENTS HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

class graspnetAPI.utils.dexnet.grasping.contacts.Contact[source]

Bases: object

Abstract class for contact models.

class graspnetAPI.utils.dexnet.grasping.contacts.Contact3D(graspable, contact_point, in_direction=None)[source]

Bases: graspnetAPI.utils.dexnet.grasping.contacts.Contact

3D contact points.

graspable

object to use to get contact information

Type

GraspableObject3D

contact_point

point of contact on the object

Type

3x1 numpy.ndarray

in_direction

direction along which contact was made

Type

3x1 numpy.ndarray

normal

surface normal at the contact point

Type

normalized 3x1 numpy.ndarray

friction_cone(num_cone_faces=8, friction_coef=0.5)[source]

Computes the friction cone and normal for a contact point.

Parameters

  • num_cone_faces (int) – number of cone faces to use in discretization

  • friction_coef (float) – coefficient of friction at contact point

Returns

  • success (bool) – False when cone can’t be computed

  • cone_support (numpy.ndarray) – array where each column is a vector on the boundary of the cone

  • normal (normalized 3x1 numpy.ndarray) – outward facing surface normal

property graspable
property in_direction
property normal
normal_force_magnitude()[source]

Returns the component of the force that the contact would apply along the normal direction.

Returns

magnitude of force along object surface normal

Return type

float

plot_friction_cone(color='y', scale=1.0)[source]
property point
reference_frame(align_axes=True)[source]

Returns the local reference frame of the contact. Z axis in the in direction (or surface normal if not specified) X and Y axes in the tangent plane to the direction

Parameters

align_axes (bool) – whether or not to align to the object axes

Returns

rigid transformation from contact frame to object frame

Return type

RigidTransform

surface_information(width, num_steps, sigma_range=0.1, sigma_spatial=1, back_up=0.0, max_projection=0.1, direction=None, debug_objs=None, samples_per_grid=2)[source]

Returns the local surface window, gradient, and curvature for a single contact.

Parameters

  • width (float) – width of surface window in object frame

  • num_steps (int) – number of steps to use along the in direction

  • sigma_range (float) – bandwidth of bilateral range filter on window

  • sigma_spatial (float) – bandwidth of gaussian spatial filter of bilateral filter

  • back_up (float) – amount to back up before finding a contact in meters

  • max_projection (float) – maximum amount to search forward for a contact (meters)

  • direction (3x1 numpy.ndarray) – direction along width to render the window

  • debug_objs (list) – list to put debugging info into

  • samples_per_grid (float) – number of samples per grid when finding contacts

Returns

surface_window – window information for local surface patch of contact on the given object

Return type

SurfaceWindow

surface_window_projection(width=0.01, num_steps=21, max_projection=0.1, back_up=0.0, samples_per_grid=2.0, sigma_range=0.1, sigma_spatial=1, direction=None, compute_pca=False, vis=False, debug_objs=None)[source]

Projects the local surface onto the tangent plane at a contact point.

Parameters

  • width (float) – width of the window in obj frame

  • num_steps (int) – number of steps to use along the in direction

  • max_projection (float) – maximum amount to search forward for a contact (meters)

  • back_up (float) – amount to back up before finding a contact in meters

  • samples_per_grid (float) – number of samples per grid when finding contacts

  • sigma_range (float) – bandwidth of bilateral range filter on window

  • sigma_spatial (float) – bandwidth of gaussian spatial filter of bilateral filter

  • direction (3x1 numpy.ndarray) – dir to do the projection along

Returns

window – array of distances from tangent plane to obj, False if surface window can’t be computed

Return type

NUM_STEPSxNUM_STEPS numpy.ndarray

surface_window_projection_unaligned(width=0.01, num_steps=21, max_projection=0.1, back_up=0.0, samples_per_grid=2.0, sigma=1.5, direction=None, vis=False)[source]

Projects the local surface onto the tangent plane at a contact point. Deprecated.

surface_window_sdf(width=0.01, num_steps=21)[source]

Returns a window of SDF values on the tangent plane at a contact point. Used for patch computation.

Parameters

  • width (float) – width of the window in obj frame

  • num_steps (int) – number of steps to use along the contact in direction

Returns

window – array of distances from tangent plane to obj along in direction, False if surface window can’t be computed

Return type

NUM_STEPSxNUM_STEPS numpy.ndarray

tangents(direction=None, align_axes=True, max_samples=1000)[source]

Returns the direction vector and tangent vectors at a contact point. The direction vector defaults to the inward-facing normal vector at this contact. The direction and tangent vectors for a right handed coordinate frame.

Parameters

  • direction (3x1 numpy.ndarray) – direction to find orthogonal plane for

  • align_axes (bool) – whether or not to align the tangent plane to the object reference frame

  • max_samples (int) – number of samples to use in discrete optimization for alignment of reference frame

Returns

  • direction (normalized 3x1 numpy.ndarray) – direction to find orthogonal plane for

  • t1 (normalized 3x1 numpy.ndarray) – first tangent vector, x axis

  • t2 (normalized 3x1 numpy.ndarray) – second tangent vector, y axis

torques(forces)[source]

Get the torques that can be applied by a set of force vectors at the contact point.

Parameters

forces (3xN numpy.ndarray) – the forces applied at the contact

Returns

  • success (bool) – whether or not computation was successful

  • torques (3xN numpy.ndarray) – the torques that can be applied by given forces at the contact

class graspnetAPI.utils.dexnet.grasping.contacts.SurfaceWindow(proj_win, grad, hess_x, hess_y, gauss_curvature)[source]

Bases: object

Struct for encapsulating local surface window features.

proj_win

the window of distances to a surface (depth image created by orthographic projection)

Type

NxN numpy.ndarray

grad

X and Y gradients of the projection window

Type

NxN numpy.ndarray

hess_x

hessian, partial derivatives of the X gradient window

Type

NxN numpy.ndarray

hess_y

hessian, partial derivatives of the Y gradient window

Type

NxN numpy.ndarray

gauss_curvature

gauss curvature at each point (function of hessian determinant)

Type

NxN numpy.ndarray

asarray(proj_win_weight=0.0, grad_x_weight=0.0, grad_y_weight=0.0, curvature_weight=0.0)[source]
property curvature
property grad_x
property grad_x_2d
property grad_y
property grad_y_2d
property proj_win
property proj_win_2d

graspnetAPI.utils.dexnet.grasping.grasp module

class graspnetAPI.utils.dexnet.grasping.grasp.Grasp[source]

Bases: object

Abstract grasp class.

configuration[source]

vector specifying the parameters of the grasp (e.g. hand pose, opening width, joint angles, etc)

Type

numpy.ndarray

frame[source]

string name of grasp reference frame (defaults to obj)

Type

str

abstract close_fingers(obj)[source]

Finds the contact points by closing on the given object.

Parameters

obj (GraspableObject3D) – object to find contacts on

abstract configuration()[source]

Returns the numpy array representing the hand configuration

abstract static configuration_from_params(*params)[source]

Convert param list to a configuration vector for the class

abstract frame()[source]

Returns the string name of the grasp reference frame

abstract static params_from_configuration(configuration)[source]

Convert configuration vector to a set of params for the class

samples_per_grid = 2
class graspnetAPI.utils.dexnet.grasping.grasp.ParallelJawPtGrasp3D(configuration, max_grasp_depth=0, frame='object', grasp_id=None)[source]

Bases: graspnetAPI.utils.dexnet.grasping.grasp.PointGrasp

Parallel Jaw point grasps in 3D space.

property T_grasp_obj

Rigid transformation from grasp frame to object frame. Rotation matrix is X-axis along approach direction, Y axis pointing between the jaws, and Z-axis orthogonal. Translation vector is the grasp center.

Returns

transformation from grasp to object coordinates

Return type

RigidTransform

property approach_angle

approach angle of the grasp

Type

float

property axis

normalized 3-vector specifying the line between the jaws

Type

numpy.ndarray

static axis_from_endpoints(g1, g2)[source]

Normalized axis of grasp from endpoints as np 3-arrays

property center

3-vector specifying the center of the jaws

Type

numpy.ndarray

static center_from_endpoints(g1, g2)[source]

Grasp center from endpoints as np 3-arrays

close_fingers(obj, vis=False, check_approach=True, approach_dist=1.0)[source]

Steps along grasp axis to find the locations of contact with an object

Parameters

  • obj (GraspableObject3D) – object to close fingers on

  • vis (bool) – whether or not to plot the line of action and contact points

  • check_approach (bool) – whether or not to check if the contact points can be reached

  • approach_dist (float) – how far back to check the approach distance, only if checking the approach is set

Returns

  • success (bool) – whether or not contacts were found

  • c1 (Contact3D) – the contact point for jaw 1

  • c2 (Contact3D) – the contact point for jaw 2

close_fingers_with_contacts(obj, contacts, vis=False, check_approach=True, approach_dist=0.5)[source]

Steps along grasp axis to find the locations of contact with an object

Parameters

  • obj (GraspableObject3D) – object to close fingers on

  • vis (bool) – whether or not to plot the line of action and contact points

  • check_approach (bool) – whether or not to check if the contact points can be reached

  • approach_dist (float) – how far back to check the approach distance, only if checking the approach is set

Returns

  • success (bool) – whether or not contacts were found

  • c1 (Contact3D) – the contact point for jaw 1

  • c2 (Contact3D) – the contact point for jaw 2

property close_width

minimum opening width of the jaws

Type

float

property configuration

vector specifying the parameters of the grasp as follows (grasp_center, grasp_axis, grasp_angle, grasp_width, jaw_width)

Type

numpy.ndarray

static configuration_from_params(center, axis, width, angle=0, jaw_width=0, min_width=0)[source]

Converts grasp parameters to a configuration vector.

static create_line_of_action(g, axis, width, obj, num_samples, min_width=0, convert_grid=True)[source]

Creates a straight line of action, or list of grid points, from a given point and direction in world or grid coords

Parameters

  • g (3x1 numpy.ndarray) – start point to create the line of action

  • axis (normalized 3x1 numpy.ndarray) – normalized numpy 3 array of grasp direction

  • width (float) – the grasp width

  • num_samples (int) – number of discrete points along the line of action

  • convert_grid (bool) – whether or not the points are specified in world coords

Returns

line_of_action – coordinates to pass through in 3D space for contact checking

Return type

list of 3x1 numpy.ndarrays

static distance(g1, g2, alpha=0.05)[source]

Evaluates the distance between two grasps.

Parameters
Returns

distance between grasps g1 and g2

Return type

float

property endpoints

returns: location of jaws in 3D space at max opening width :rtype: numpy.ndarray

static find_contact(line_of_action, obj, vis=False, strict=False)[source]

Find the point at which a point traveling along a given line of action hits a surface.

Parameters

  • line_of_action (list of 3x1 numpy.ndarray) – the points visited as the fingers close (grid coords)

  • obj (GraspableObject3D) – to check contacts on

  • vis (bool) – whether or not to display the contact check (for debugging)

Returns

  • contact_found (bool) – whether or not the point contacts the object surface

  • contact (Contact3D) – found along line of action (None if contact not found)

property frame

name of grasp reference frame

Type

str

grasp_angles_from_stp_z(stable_pose)[source]

Get angles of the the grasp from the table plane: 1) the angle between the grasp axis and table normal 2) the angle between the grasp approach axis and the table normal

Parameters

stable_pose (StablePose or RigidTransform) – the stable pose to compute the angles for

Returns

  • psi (float) – grasp y axis rotation from z axis in stable pose

  • phi (float) – grasp x axis rotation from z axis in stable pose

static grasp_from_contact_and_axis_on_grid(obj, grasp_c1_world, grasp_axis_world, grasp_width_world, grasp_angle=0, jaw_width_world=0, min_grasp_width_world=0, vis=False, backup=0.5)[source]

Creates a grasp from a single contact point in grid coordinates and direction in grid coordinates.

Parameters

  • obj (GraspableObject3D) – object to create grasp for

  • grasp_c1_grid (3x1 numpy.ndarray) – contact point 1 in world

  • grasp_axis (normalized 3x1 numpy.ndarray) – normalized direction of the grasp in world

  • grasp_width_world (float) – grasp_width in world coords

  • jaw_width_world (float) – width of jaws in world coords

  • min_grasp_width_world (float) – min closing width of jaws

  • vis (bool) – whether or not to visualize the grasp

Returns

  • g (ParallelJawGrasp3D) – grasp created by finding the second contact

  • c1 (Contact3D) – first contact point on the object

  • c2 (Contact3D) – second contact point on the object

static grasp_from_endpoints(g1, g2, width=None, approach_angle=0, close_width=0)[source]

Create a grasp from given endpoints in 3D space, making the axis the line between the points.

Parameters

  • g1 (numpy.ndarray) – location of the first jaw

  • g2 (numpy.ndarray) – location of the second jaw

  • width (float) – maximum opening width of jaws

  • approach_angle (float) – approach angle of grasp

  • close_width (float) – width of gripper when fully closed

grasp_y_axis_offset(theta)[source]

Return a new grasp with the given approach angle.

Parameters

theta (float) – approach angle for the new grasp

Returns

grasp with the given approach angle

Return type

ParallelJawPtGrasp3D

gripper_pose(gripper=None)[source]

Returns the RigidTransformation from the gripper frame to the object frame when the gripper is executing the given grasp. Differs from the grasp reference frame because different robots use different conventions for the gripper reference frame.

Parameters

gripper (RobotGripper) – gripper to get the pose for

Returns

transformation from gripper frame to object frame

Return type

RigidTransform

property id

id of grasp

Type

int

property jaw_width

width of the jaws in the tangent plane to the grasp axis

Type

float

property open_width

maximum opening width of the jaws

Type

float

parallel_table(stable_pose)[source]

Returns a grasp with approach_angle set to be perpendicular to the table normal specified in the given stable pose.

Parameters

stable_pose (StablePose) – the pose specifying the table

Returns

aligned grasp

Return type

ParallelJawPtGrasp3D

static params_from_configuration(configuration)[source]

Converts configuration vector into grasp parameters.

Returns

  • grasp_center (numpy.ndarray) – center of grasp in 3D space

  • grasp_axis (numpy.ndarray) – normalized axis of grasp in 3D space

  • max_width (float) – maximum opening width of jaws

  • angle (float) – approach angle

  • jaw_width (float) – width of jaws

  • min_width (float) – minimum closing width of jaws

perpendicular_table(stable_pose)[source]

Returns a grasp with approach_angle set to be aligned width the table normal specified in the given stable pose.

Parameters

stable_pose (StablePose or RigidTransform) – the pose specifying the orientation of the table

Returns

aligned grasp

Return type

ParallelJawPtGrasp3D

project_camera(T_obj_camera, camera_intr)[source]

Project a grasp for a given gripper into the camera specified by a set of intrinsics.

Parameters

  • T_obj_camera (autolab_core.RigidTransform) – rigid transformation from the object frame to the camera frame

  • camera_intr (perception.CameraIntrinsics) – intrinsics of the camera to use

property rotated_full_axis

Rotation matrix from canonical grasp reference frame to object reference frame. X axis points out of the gripper palm along the grasp approach angle, Y axis points between the jaws, and the Z axs is orthogonal.

Returns

rotation matrix of grasp

Return type

numpy.ndarray

surface_information(graspable, width=0.02, num_steps=21, direction=None)[source]

Return the patch surface information at the contacts that this grasp makes on a graspable.

Parameters

  • graspable (GraspableObject3D) – object to get surface information for

  • width (float) – width of the window in obj frame

  • num_steps (int) – number of steps

Returns

surface patches, one for each contact

Return type

list of SurfaceWindow

property unrotated_full_axis

Rotation matrix from canonical grasp reference frame to object reference frame. X axis points out of the gripper palm along the 0-degree approach direction, Y axis points between the jaws, and the Z axs is orthogonal.

Returns

rotation matrix of grasp

Return type

numpy.ndarray

vis_grasp(obj, *args, **kwargs)[source]
static width_from_endpoints(g1, g2)[source]

Width of grasp from endpoints

class graspnetAPI.utils.dexnet.grasping.grasp.PointGrasp[source]

Bases: graspnetAPI.utils.dexnet.grasping.grasp.Grasp

Abstract grasp class for grasps with a point contact model.

configuration

vector specifying the parameters of the grasp (e.g. hand pose, opening width, joint angles, etc)

Type

numpy.ndarray

frame

string name of grasp reference frame (defaults to obj)

Type

str

abstract create_line_of_action(axis, width, obj, num_samples)[source]

Creates a line of action, or the points in space that the grasp traces out, from a point g in world coordinates on an object.

Returns

  • bool – whether or not successful

  • list of numpy.ndarray – points in 3D space along the line of action

class graspnetAPI.utils.dexnet.grasping.grasp.VacuumPoint(configuration, frame='object', grasp_id=None)[source]

Bases: graspnetAPI.utils.dexnet.grasping.grasp.Grasp

Defines a vacuum target point and axis in 3D space (5 DOF)

property axis
property center
property configuration

Returns the numpy array representing the hand configuration

static configuration_from_params(center, axis)[source]

Converts grasp parameters to a configuration vector.

property frame

Returns the string name of the grasp reference frame

static params_from_configuration(configuration)[source]

Converts configuration vector into vacuum grasp parameters.

Returns

  • center (numpy.ndarray) – center of grasp in 3D space

  • axis (numpy.ndarray) – normalized axis of grasp in 3D space

graspnetAPI.utils.dexnet.grasping.grasp_quality_config module

Copyright ©2017. The Regents of the University of California (Regents). All Rights Reserved. Permission to use, copy, modify, and distribute this software and its documentation for educational, research, and not-for-profit purposes, without fee and without a signed licensing agreement, is hereby granted, provided that the above copyright notice, this paragraph and the following two paragraphs appear in all copies, modifications, and distributions. Contact The Office of Technology Licensing, UC Berkeley, 2150 Shattuck Avenue, Suite 510, Berkeley, CA 94720-1620, (510) 643- 7201, otl@berkeley.edu, http://ipira.berkeley.edu/industry-info for commercial licensing opportunities.

IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED HEREUNDER IS PROVIDED “AS IS”. REGENTS HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

class graspnetAPI.utils.dexnet.grasping.grasp_quality_config.GraspQualityConfig(config)[source]

Bases: object

Base wrapper class for parameters used in grasp quality computation. Used to elegantly enforce existence and type of required parameters.

config

dictionary mapping parameter names to parameter values

Type

dict

abstract check_valid(config)[source]

Raise an exception if the config is missing required keys

contains(key)[source]

Checks whether or not the key is supported

keys()[source]
class graspnetAPI.utils.dexnet.grasping.grasp_quality_config.GraspQualityConfigFactory[source]

Bases: object

Helper class to automatically create grasp quality configurations of different types.

static create_config(config)[source]

Automatically create a quality config from a dictionary.

Parameters

config (dict) – dictionary mapping parameter names to parameter values

class graspnetAPI.utils.dexnet.grasping.grasp_quality_config.QuasiStaticGraspQualityConfig(config)[source]

Bases: graspnetAPI.utils.dexnet.grasping.grasp_quality_config.GraspQualityConfig

Parameters for quasi-static grasp quality computation.

config

dictionary mapping parameter names to parameter values

Type

dict

Notes

Required configuration key-value pairs in Other Parameters.

Other Parameters

  • quality_method (str) – string name of quasi-static quality metric

  • friction_coef (float) – coefficient of friction at contact point

  • num_cone_faces (int) – number of faces to use in friction cone approximation

  • soft_fingers (bool) – whether to use a soft finger model

  • quality_type (str) – string name of grasp quality type (e.g. quasi-static, robust quasi-static)

  • check_approach (bool) – whether or not to check the approach direction

REQUIRED_KEYS = ['quality_method', 'friction_coef', 'num_cone_faces', 'soft_fingers', 'quality_type', 'check_approach', 'all_contacts_required']
__copy__()[source]

Makes a copy of the config

check_valid(config)[source]

Raise an exception if the config is missing required keys

class graspnetAPI.utils.dexnet.grasping.grasp_quality_config.RobustQuasiStaticGraspQualityConfig(config)[source]

Bases: graspnetAPI.utils.dexnet.grasping.grasp_quality_config.GraspQualityConfig

Parameters for quasi-static grasp quality computation.

config

dictionary mapping parameter names to parameter values

Type

dict

Notes

Required configuration key-value pairs in Other Parameters.

Other Parameters

  • quality_method (str) – string name of quasi-static quality metric

  • friction_coef (float) – coefficient of friction at contact point

  • num_cone_faces (int) – number of faces to use in friction cone approximation

  • soft_fingers (bool) – whether to use a soft finger model

  • quality_type (str) – string name of grasp quality type (e.g. quasi-static, robust quasi-static)

  • check_approach (bool) – whether or not to check the approach direction

  • num_quality_samples (int) – number of samples to use

ROBUST_REQUIRED_KEYS = ['num_quality_samples']
__copy__()[source]

Makes a copy of the config

check_valid(config)[source]

Raise an exception if the config is missing required keys

graspnetAPI.utils.dexnet.grasping.grasp_quality_function module

graspnetAPI.utils.dexnet.grasping.graspable_object module

Copyright ©2017. The Regents of the University of California (Regents). All Rights Reserved. Permission to use, copy, modify, and distribute this software and its documentation for educational, research, and not-for-profit purposes, without fee and without a signed licensing agreement, is hereby granted, provided that the above copyright notice, this paragraph and the following two paragraphs appear in all copies, modifications, and distributions. Contact The Office of Technology Licensing, UC Berkeley, 2150 Shattuck Avenue, Suite 510, Berkeley, CA 94720-1620, (510) 643- 7201, otl@berkeley.edu, http://ipira.berkeley.edu/industry-info for commercial licensing opportunities.

IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED HEREUNDER IS PROVIDED “AS IS”. REGENTS HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

class graspnetAPI.utils.dexnet.grasping.graspable_object.GraspableObject(sdf, mesh, key='', model_name='', mass=1.0, convex_pieces=None)[source]

Bases: object

Encapsulates geometric structures for computing contact in grasping.

sdf

signed distance field, for quickly computing contact points

Type

Sdf3D

mesh

3D triangular mesh to specify object geometry, should match SDF

Type

Mesh3D

key

object identifier, usually given from the database

Type

str

model_name

name of the object mesh as a .obj file, for use in collision checking

Type

str

mass

mass of the object

Type

float

convex_pieces

convex decomposition of the object geom for collision checking

Type

list of Mesh3D

property convex_pieces
property key
property mass
property mesh
property model_name
property sdf
class graspnetAPI.utils.dexnet.grasping.graspable_object.GraspableObject3D(sdf, mesh, key='', model_name='', mass=1.0, convex_pieces=None)[source]

Bases: graspnetAPI.utils.dexnet.grasping.graspable_object.GraspableObject

3D Graspable object for computing contact in grasping.

sdf

signed distance field, for quickly computing contact points

Type

Sdf3D

mesh

3D triangular mesh to specify object geometry, should match SDF

Type

Mesh3D

key

object identifier, usually given from the database

Type

str

model_name

name of the object mesh as a .obj file, for use in collision checking

Type

str

mass

mass of the object

Type

float

convex_pieces

convex decomposition of the object geom for collision checking

Type

list of Mesh3D

moment_arm(x)[source]

Computes the moment arm to a point x.

Parameters

x (3x1 numpy.ndarray) – point to get moment arm for

Returns

Return type

3x1 numpy.ndarray

rescale(scale)[source]

Rescales uniformly by a given factor.

Parameters

scale (float) – the amount to scale the object

Returns

the graspable object rescaled by the given factor

Return type

GraspableObject3D

surface_information(grasp, width, num_steps, plot=False, direction1=None, direction2=None)[source]

Returns the patches on this object for a given grasp.

Parameters

  • grasp (ParallelJawPtGrasp3D) – grasp to get the patch information for

  • width (float) – width of jaw opening

  • num_steps (int) – number of steps

  • plot (bool) – whether to plot the intermediate computation, for debugging

  • direction1 (normalized 3x1 numpy.ndarray) – direction along which to compute the surface information for the first jaw, if None then defaults to grasp axis

  • direction2 (normalized 3x1 numpy.ndarray) – direction along which to compute the surface information for the second jaw, if None then defaults to grasp axis

Returns

surface patches, one for each contact

Return type

list of SurfaceWindow

transform(delta_T)[source]

Transform by a delta transform.

Parameters

delta_T (RigidTransform) – the transformation from the current reference frame to the alternate reference frame

Returns

graspable object trasnformed by the delta

Return type

GraspableObject3D

graspnetAPI.utils.dexnet.grasping.quality module

class graspnetAPI.utils.dexnet.grasping.quality.PointGraspMetrics3D[source]

Bases: object

Class to wrap functions for quasistatic point grasp quality metrics.

static ferrari_canny_L1(forces, torques, normals, soft_fingers=False, params=None, wrench_norm_thresh=0.001, wrench_regularizer=1e-10)[source]

Ferrari & Canny’s L1 metric. Also known as the epsilon metric.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

Returns

float

Return type

value of metric

static ferrari_canny_L1_force_only(forces, torques, normals, soft_fingers=False, params=None, wrench_norm_thresh=0.001, wrench_regularizer=1e-10)[source]

Ferrari & Canny’s L1 metric with force only. Also known as the epsilon metric.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

Returns

float

Return type

value of metric

static force_closure(c1, c2, friction_coef, use_abs_value=True)[source]

” Checks force closure using the antipodality trick.

Parameters

  • c1 (Contact3D) – first contact point

  • c2 (Contact3D) – second contact point

  • friction_coef (float) – coefficient of friction at the contact point

  • use_abs_value (bool) – whether or not to use directoinality of the surface normal (useful when mesh is not oriented)

Returns

int

Return type

1 if in force closure, 0 otherwise

static force_closure_qp(forces, torques, normals, soft_fingers=False, wrench_norm_thresh=0.001, wrench_regularizer=1e-10, params=None)[source]

Checks force closure by solving a quadratic program (whether or not zero is in the convex hull)

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

int

Return type

1 if in force closure, 0 otherwise

static grasp_isotropy(forces, torques, normals, soft_fingers=False, params=None)[source]

Condition number of grasp matrix - ratio of “weakest” wrench that the grasp can exert to the “strongest” one.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

float

Return type

value of grasp isotropy metric

static grasp_matrix(forces, torques, normals, soft_fingers=False, finger_radius=0.005, params=None)[source]

Computes the grasp map between contact forces and wrenchs on the object in its reference frame.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • finger_radius (float) – the radius of the fingers to use

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

G – grasp map

Return type

6xM numpy.ndarray

static grasp_quality(grasp, obj, params, contacts=None, vis=False)[source]

Computes the quality of a two-finger point grasps on a given object using a quasi-static model.

Parameters

  • grasp (ParallelJawPtGrasp3D) – grasp to evaluate

  • obj (GraspableObject3D) – object to evaluate quality on

  • params (GraspQualityConfig) – parameters of grasp quality function

static min_norm_vector_in_facet(facet, wrench_regularizer=1e-10)[source]

Finds the minimum norm point in the convex hull of a given facet (aka simplex) by solving a QP.

Parameters

  • facet (6xN numpy.ndarray) – vectors forming the facet

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

Returns

  • float – minimum norm of any point in the convex hull of the facet

  • Nx1 numpy.ndarray – vector of coefficients that achieves the minimum

static min_singular(forces, torques, normals, soft_fingers=False, params=None)[source]

Min singular value of grasp matrix - measure of wrench that grasp is “weakest” at resisting.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

float

Return type

value of smallest singular value

static partial_closure(forces, torques, normals, soft_fingers=False, wrench_norm_thresh=0.001, wrench_regularizer=1e-10, params=None)[source]

Evalutes partial closure: whether or not the forces and torques can resist a specific wrench. Estimates resistance by sollving a quadratic program (whether or not the target wrench is in the convex hull).

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

int

Return type

1 if in partial closure, 0 otherwise

static wrench_in_positive_span(wrench_basis, target_wrench, force_limit, num_fingers=1, wrench_norm_thresh=0.0001, wrench_regularizer=1e-10)[source]

Check whether a target can be exerted by positive combinations of wrenches in a given basis with L1 norm fonger force limit limit.

Parameters

  • wrench_basis (6xN numpy.ndarray) – basis for the wrench space

  • target_wrench (6x1 numpy.ndarray) – target wrench to resist

  • force_limit (float) – L1 upper bound on the forces per finger (aka contact point)

  • num_fingers (int) – number of contacts, used to enforce L1 finger constraint

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

Returns

  • int – whether or not wrench can be resisted

  • float – minimum norm of the finger forces required to resist the wrench

static wrench_resistance(forces, torques, normals, soft_fingers=False, wrench_norm_thresh=0.001, wrench_regularizer=1e-10, finger_force_eps=1e-09, params=None)[source]

Evalutes wrench resistance: the inverse norm of the contact forces required to resist a target wrench Estimates resistance by sollving a quadratic program (min normal contact forces to produce a wrench).

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • wrench_norm_thresh (float) – threshold to use to determine equivalence of target wrenches

  • wrench_regularizer (float) – small float to make quadratic program positive semidefinite

  • finger_force_eps (float) – small float to prevent numeric issues in wrench resistance metric

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

float

Return type

value of wrench resistance metric

static wrench_volume(forces, torques, normals, soft_fingers=False, params=None)[source]

Volume of grasp matrix singular values - score of all wrenches that the grasp can resist.

Parameters

  • forces (3xN numpy.ndarray) – set of forces on object in object basis

  • torques (3xN numpy.ndarray) – set of torques on object in object basis

  • normals (3xN numpy.ndarray) – surface normals at the contact points

  • soft_fingers (bool) – whether or not to use the soft finger contact model

  • params (GraspQualityConfig) – set of parameters for grasp matrix and contact model

Returns

float

Return type

value of wrench volume

Module contents

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