grasps_interpoler.py

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#!/usr/bin/env python
#
# Copyright 2011 Shadow Robot Company Ltd.
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 2 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along
# with this program.  If not, see <http://www.gnu.org/licenses/>.
#


class GraspInterpoler(object):
    def __init__(self, grasp_from, grasp_to="current"):
        """
        interpolate from one grasp to another

        Keyword arguments
        grasp_from -- goes from this grasp
        grasp_to -- to this grasp (if not defined, then consider
        the current position of the hand as a grasp)
        """
        self.percentage = 0
        self.grasp_from = grasp_from
        self.grasp_to = grasp_to

        # store the joints in common between the 2 grasps, with a table
        # [ starting_value, end_value ]
        self.from_grasp1_to_grasp2 = {}

        for joint in self.grasp_from.joints_and_positions.keys():
            # if joint in self.grasp_to.joints_and_positions.keys():
            self.from_grasp1_to_grasp2.update({
                joint: [self.grasp_from.joints_and_positions.get(joint),
                        self.grasp_to.joints_and_positions.get(joint)]})

    def set_percentage_grasp1_to_grasp2(self, percentage):
        """
        move to a given percentage between grasp1 and grasp2

        Keyword arguments
        percentage -- must be between 0 and 100
        """
        self.percentage = percentage
        positions_to_send = {}

        for joint in self.from_grasp1_to_grasp2.iteritems():
            new_target = percentage / 100.0 * (joint[1][1] - joint[1][0])
            positions_to_send.update({joint[0]: new_target})

        return positions_to_send

    def interpolate(self, percentage):
        position_to_send = {}
        for name, position in self.grasp_to.joints_and_positions.items():
            if name in self.grasp_from.joints_and_positions.keys():
                pos_from = self.grasp_from.joints_and_positions[name]
                pos_to = position
                position_to_send[name] = pos_from + (pos_to - pos_from) * (percentage / 100.0)
        return position_to_send