motion_demo.py

Go to the documentation of this file.

#!/usr/bin/env python

# Software License Agreement (BSD License)
#
# Copyright (c) 2014-2017, Dataspeed Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
# 
#     * Redistributions of source code must retain the above copyright notice,
#       this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright notice,
#       this list of conditions and the following disclaimer in the documentation
#       and/or other materials provided with the distribution.
#     * Neither the name of Dataspeed Inc. nor the names of its
#       contributors may be used to endorse or promote products derived from this
#       software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import rospy
from geometry_msgs.msg import Twist

def timer_callback(event):
  pub.publish(twist_output)

def simple_motion(twist, duration):
  global twist_output

  opposite_twist = Twist()
  opposite_twist.linear.x = -twist.linear.x
  opposite_twist.linear.y = -twist.linear.y
  opposite_twist.angular.z = -twist.angular.z

  if rospy.is_shutdown():
    return

  twist_output = twist
  rospy.sleep(duration)
  twist_output = zero_twist
  rospy.sleep(1.0)
  twist_output = opposite_twist
  rospy.sleep(duration)
  twist_output = zero_twist
  rospy.sleep(1.0)

def motion_demo():
  global pub
  pub = rospy.Publisher('/mobility_base/cmd_vel', Twist, queue_size=1)
  rospy.init_node('motion_demo');

  global zero_twist
  zero_twist = Twist()
  zero_twist.linear.x = 0
  zero_twist.linear.y = 0
  zero_twist.angular.z = 0

  global twist_output
  twist_output = Twist()

  rospy.Timer(rospy.Duration(0.1), timer_callback)

  speed = 0.2
  dist = 1 / 3.28
  vel = Twist()
  
  # Rotate
  vel.linear.x = 0
  vel.linear.y = 0
  vel.angular.z = 0.628
  simple_motion(vel, 10.2)

  # North
  vel.linear.x = speed
  vel.linear.y = 0
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

  # North-East
  vel.linear.x = 0.707 * speed
  vel.linear.y = -0.707 * speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)
  
  # East
  vel.linear.x = 0
  vel.linear.y = -speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)
  
  # South-East
  vel.linear.x = -0.707 * speed
  vel.linear.y = -0.707 * speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

  # South
  vel.linear.x = -speed
  vel.linear.y = 0
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

  # South-West
  vel.linear.x = -0.707 * speed
  vel.linear.y = 0.707 * speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

  # West
  vel.linear.x = 0
  vel.linear.y = speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

  # North-West
  vel.linear.x = 0.707 * speed
  vel.linear.y = 0.707 * speed
  vel.angular.z = 0
  simple_motion(vel, dist/speed)

if __name__ == '__main__':
  motion_demo()