Modifying Sensor Data with ROS

 

Here is a sample code that modifies sensor data with ROS:

import rospy
from sensor_msgs.msg import Imu

def imu_callback(msg, pub):
 msg.linear_acceleration.z += 9.3
 pub.publish(msg)

def main():
 rospy.init_node('imu_without_g')
 pub = rospy.Publisher('imu_without_g', Imu, queue_size=10)
 rospy.Subscriber('imu/data', Imu, imu_callback,callback_args=pub) 
 rospy.spin()

if __name__ == '__main__':
 main()

def imu_callback(msg, pub):
 msg.linear_acceleration.z += 9.3
 pub.publish(msg)

The callback is whenever Imu msg arrive, with an additional argument of pub (which is specified in the rospy.Subscriber call). I can modify the msg using the dot notation (with names you can find out with command rosmsg show sensor_msgs/Imu).

def main():
 rospy.init_node('imu_without_g')
 pub = rospy.Publisher('imu_without_g', Imu, queue_size=10)
 rospy.Subscriber('imu/data', Imu, imu_callback,callback_args=pub) 
 rospy.spin()

I initialize a publisher to publish modified IMU data. Since this modified data will be published onto a different topic, you’ll have to redirect the topic of the imu for each nodes that use IMU data in the future.