Cris ThomasJiss Joseph Thomas
Published © GPL3+

Collision Evasion System for Autonomous Robots

A robust, inexpensive, yet powerful collision detection system for the purpose of small autonomous robots

ExpertWork in progress20 hours1,249

Things used in this project

Hardware components

Raspberry Pi 3 Model B
Raspberry Pi 3 Model B
×1
Stereo Camera
Custom made from Microsoft cameras of the same make
×1

Software apps and online services

OpenVINO™ toolkit
Intel OpenVINO™ toolkit
OpenCV
OpenCV

Story

Read more

Schematics

Configuration

Code

Evasion_implementation

Python
Evasive algorithm developed for micro UAVs
#!/usr/bin/env python
import rospy
import thread
import time
import mavros
from geometry_msgs.msg import PoseStamped, Quaternion
from mavros_msgs.msg import State
from mavros_msgs.srv import CommandBool, SetMode
from std_msgs.msg import String
from mavros_msgs.srv import *
from math import *
from tf.transformations import quaternion_from_euler
mavros.set_namespace()
# Set collision threshold
double collision_thresh = 2.0 #meters
local_pos_pub = rospy.Publisher(mavros.get_topic('setpoint_position', 'local'), PoseStamped, queue_size=10)
target_pose = PoseStamped()
target_pose.pose.position.x = 0.0
target_pose.pose.position.y = 0.0
target_pose.pose.position.z = 0.0
thread_stop_flag = True
posthread = 0
def position_tracking_thread(target_pose):
global thread_stop_flag
rate = rospy.Rate(10)
while not thread_stop_flag:
local_pos_pub.publish(target_pose)
rate.sleep()
def position_control(x=0, y=0, z=0):
print "begining position control"
global thread_stop_flag
global target_pose
global posthread
thread_stop_flag = True
target_pose.pose.position.x = float(x)
target_pose.pose.position.y = float(y)
target_pose.pose.position.z = float(z)
yaw_degrees = 0  # North
yaw = radians(yaw_degrees)
quaternion = quaternion_from_euler(0, 0, yaw)
target_pose.pose.orientation = Quaternion(*quaternion)
target_pose.header.frame_id = "base_footprint"
now = rospy.get_rostime()
# Update timestamp and publish pose
target_pose.header.stamp = rospy.Time.now()
try:
print "waiting for previous thread to join"
#	posthread.join()
time.sleep(1)
print "thread joined, starting new thread"
thread_stop_flag = False
posthread = thread.start_new_thread( position_tracking_thread, (target_pose,) )
except e:
print "Error in threeady thingy ",e
print "waiting to start offboard mode"
time.sleep(1)
setOffboardMode()
print "offboard mode commanded"
def setOffboardMode():
rospy.wait_for_service('/mavros/set_mode')
try:
flightModeService = rospy.ServiceProxy('/mavros/set_mode', mavros_msgs.srv.SetMode)
isModeChanged = flightModeService(custom_mode='OFFBOARD')
except rospy.ServiceException, e:
print "service set_mode call failed: %s. OFFBOARD Mode could not be set"%e
def setStabilizedMode():
global thread_stop_flag
thread_stop_flag = True
rospy.wait_for_service('/mavros/set_mode')
try:
flightModeService = rospy.ServiceProxy('/mavros/set_mode', mavros_msgs.srv.SetMode)
isModeChanged = flightModeService(custom_mode='STABILIZED')
except rospy.ServiceException, e:
print "service set_mode call failed: %s. STABILIZED Mode could not be set. Check that GPS is enabled"%e
def setTakeoffMode():
rospy.wait_for_service('/mavros/cmd/takeoff')
try:
takeoffService = rospy.ServiceProxy('/mavros/cmd/takeoff', mavros_msgs.srv.CommandTOL)
takeoffService(altitude = 2, latitude = 0, longitude = 0, min_pitch = 0, yaw = 0)
except rospy.ServiceException, e:
print "Service takeoff call failed: %s"%e
def setLandMode():
rospy.wait_for_service('/mavros/cmd/land')
try:
landService = rospy.ServiceProxy('/mavros/cmd/land', mavros_msgs.srv.CommandTOL)
isLanding = landService(altitude = 0, latitude = 0, longitude = 0, min_pitch = 0, yaw = 0)
except rospy.ServiceException, e:
print "service land call failed: %s. The vehicle cannot land "%e
def setArm():
rospy.wait_for_service('/mavros/cmd/arming')
try:
armService = rospy.ServiceProxy('/mavros/cmd/arming', mavros_msgs.srv.CommandBool)
armService(True)
except rospy.ServiceException, e:
print "Service arm call failed: %s"%e
def setDisarm():
rospy.wait_for_service('/mavros/cmd/arming')
try:
armService = rospy.ServiceProxy('/mavros/cmd/arming', mavros_msgs.srv.CommandBool)
armService(False)
except rospy.ServiceException, e:
print "Service disarm call failed: %s"%e
def pingCallback(double &msg):
if(msg.data < collision_thresh):
setOffboardMode()
position_control(x=0, y=0.5, z=0)
def menu():
print "Press"
print "1: to set mode to OFFBOARD"
print "2: to set mode to STABILIZE"
print "3: to set mode to ARM the drone"
print "4: to set mode to DISARM the drone"
print "5: to set mode to TAKEOFF"
print "6: to set mode to LAND"
print "7: Position Control"
def myLoop():
x='1'
while ((not rospy.is_shutdown())):
menu()
x = raw_input("Enter your input: ");
if (x=='1'):
setOffboardMode()
elif(x=='2'):
setStabilizedMode()
elif(x=='3'):
setArm()
elif(x=='4'):
setDisarm()
elif(x=='5'):
setTakeoffMode()
elif(x=='6'):
setLandMode()
elif(x=='7'):
xpos = raw_input("Enter x position ")
ypos = raw_input("Enter y position ")
zpos = raw_input("Enter z position ")
position_control(xpos,ypos,zpos)
else:
print "Exit"
break
if __name__ == '__main__':
rospy.init_node('dronemap_node', anonymous=True)
rospy.Subscriber("/ping_dist/data", double, pingCallback)
myLoop()

Credits

Cris Thomas

Cris Thomas

24 projects • 92 followers
Electronics and Aerospace engineer with a dedicated history in Research and Development. https://www.linkedin.com/in/crisdeodates/
Jiss Joseph Thomas

Jiss Joseph Thomas

21 projects • 55 followers

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