OpenRAVE Documentation

Source code for openravepy.examples.fastgrasping

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (C) 2009-2011 Rosen Diankov (
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
"""Finds the first feasible grasp for an object as fast as possible without generating a grasp database.

.. examplepre-block:: fastgrasping


This type of example is suited for object geometries that are dynamically created from sensor data.

.. examplepost-block:: fastgrasping
from __future__ import with_statement # for python 2.5
__author__ = 'Rosen Diankov'

from itertools import izip
import openravepy
if not __openravepy_build_doc__:
    from openravepy import *
    from numpy import *

[docs]class FastGrasping:
[docs] class GraspingException(Exception): def __init__(self,args): self.args=args
def __init__(self,robot,target): self.robot = robot self.ikmodel = databases.inversekinematics.InverseKinematicsModel(robot=robot,iktype=IkParameterization.Type.Transform6D) if not self.ikmodel.load(): self.ikmodel.autogenerate() self.gmodel = databases.grasping.GraspingModel(robot,target) self.gmodel.init(friction=0.4,avoidlinks=[])
[docs] def checkgraspfn(self, contacts,finalconfig,grasp,info): # check if grasp can be reached by robot Tglobalgrasp = self.gmodel.getGlobalGraspTransform(grasp,collisionfree=True) # have to set the preshape since the current robot is at the final grasp! self.gmodel.setPreshape(grasp) sol = self.gmodel.manip.FindIKSolution(Tglobalgrasp,True) if sol is not None: jointvalues = array(finalconfig[0]) jointvalues[self.gmodel.manip.GetArmIndices()] = sol raise self.GraspingException([grasp,jointvalues]) return True
[docs] def computeGrasp(self): approachrays = self.gmodel.computeBoxApproachRays(delta=0.02,normalanglerange=0.5) # rays to approach object standoffs = [0] # roll discretization rolls = arange(0,2*pi,0.5*pi) # initial preshape for robot is the released fingers with taskmanip = interfaces.TaskManipulation(self.robot) final,traj = taskmanip.ReleaseFingers(execute=False,outputfinal=True) preshapes = array([final]) try: self.gmodel.disableallbodies=False self.gmodel.generate(preshapes=preshapes,standoffs=standoffs,rolls=rolls,approachrays=approachrays,checkgraspfn=self.checkgraspfn,graspingnoise=0.01) return None,None # did not find anything except self.GraspingException, e: return e.args
[docs]def main(env,options): "Main example code." env.Load(options.scene) robot = env.GetRobots()[0] if options.manipname is not None: robot.SetActiveManipulator(options.manipname) # find an appropriate target bodies = [b for b in env.GetBodies() if not b.IsRobot() and linalg.norm(b.ComputeAABB().extents()) < 0.2] for body in bodies: self = FastGrasping(robot,target=body) grasp,jointvalues = self.computeGrasp() if grasp is not None: print 'grasp is found!' self.gmodel.showgrasp(grasp) self.robot.SetDOFValues(jointvalues) raw_input('press any key')
from optparse import OptionParser from openravepy.misc import OpenRAVEGlobalArguments @openravepy.with_destroy
[docs]def run(args=None): """Command-line execution of the example. :param args: arguments for script to parse, if not specified will use sys.argv """ parser = OptionParser(description='Example showing how to compute a valid grasp as fast as possible without computing a grasp set, this is used when the target objects change frequently.') OpenRAVEGlobalArguments.addOptions(parser) parser.add_option('--scene', action="store",type='string',dest='scene',default='data/wamtest1.env.xml', help='Scene file to load (default=%default)') parser.add_option('--manipname', action="store",type='string',dest='manipname',default=None, help='Choose the manipulator to perform the grasping for') (options, leftargs) = parser.parse_args(args=args) OpenRAVEGlobalArguments.parseAndCreateThreadedUser(options,main,defaultviewer=True)
if __name__ == "__main__": run()


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