look_away.py

#!/usr/bin/env python

import math
import rospy
from sensor_msgs.msg import Image, JointState
from simple_arm.srv import *


class LookAway(object):
    def __init__(self):
        rospy.init_node('look_away')

        self.sub1 = rospy.Subscriber('/simple_arm/joint_states', 
                                     JointState, self.joint_states_callback)
        self.sub2 = rospy.Subscriber("rgb_camera/image_raw", 
                                     Image, self.look_away_callback)
        self.safe_move = rospy.ServiceProxy('/arm_mover/safe_move', 
                                     GoToPosition)

        self.last_position = None
        self.arm_moving = False

        rospy.spin()

    def uniform_image(self, image):
        return all(value == image[0] for value in image)

    def coord_equal(self, coord_1, coord_2):
        if coord_1 is None or coord_2 is None:
            return False
        tolerance = .0005
        result = abs(coord_1[0] - coord_2[0]) <= abs(tolerance)
        result = result and abs(coord_1[1] - coord_2[1]) <= abs(tolerance)
        return result

    def joint_states_callback(self, data):
        if self.coord_equal(data.position, self.last_position):
            self.arm_moving = False
        else:
            self.last_position = data.position
            self.arm_moving = True

    def look_away_callback(self, data):
        if not self.arm_moving and self.uniform_image(data.data):
            try:
                rospy.wait_for_service('/arm_mover/safe_move')
                msg = GoToPositionRequest()
                msg.joint_1 = 1.57
                msg.joint_2 = 1.57
                response = self.safe_move(msg)

                rospy.logwarn("Camera detecting uniform image. \
                               Elapsed time to look at something nicer:\n%s", 
                               response)

            except rospy.ServiceException, e:
                rospy.logwarn("Service call failed: %s", e)



if __name__ == '__main__':
    try: 
        LookAway()
    except rospy.ROSInterruptException:
        pass