ShehabAldeen's profile - activity

building a ROS1 node that depends on a shared precompiled library Hello, this may be an easy question for the CMake exp

Hello,

I am trying to run the following ros2 node. however, it seems that I cannot access the msg inside the callback function.

import rclpy
from rclpy.node import Node

import time
from std_msgs.msg import String


class MinimalSubscriber(Node):

    def __init__(self):
        super().__init__('minimal_subscriber')
        self.subscription = self.create_subscription(
            String,
            'topic',
            self.listener_callback,
            10)
        self.subscription  # prevent unused variable warning
        self.topub = 0

    def listener_callback(self, msg):
        self.topub = msg.data

    def printmsg (self):
        while True:
            self.get_logger().info('I heard: "%s"' % self.topub)
            time.sleep(0.5)

def main(args=None):
    rclpy.init(args=args)

    minimal_subscriber = MinimalSubscriber()
    minimal_subscriber.printmsg()

    rclpy.spin(minimal_subscriber)


if __name__ == '__main__':

    main()

if anyone has a clue, please help.

Thank you

actually I want to have acess to the msg subscribed within a loop.

Yes, the topic is published

how to access the msg in the subscriber callback in ros2 rclpy Hello, I am trying to run the following ros2 node. howev

I made a package to control the nao robot using the Emotic EPOC+ EEG sensor to drive the robot depends on the facial expressions

basically my package consist of two nodes 1- Publisher : which read the values coming from the sensor using the Emotiv SDK and then publish which expression I am doing with my face in a topic named /emoState

2- Subscriber : which read from that topic and give the commands to the nao robot using its SDK

the problem is my publisher is too fast and so the subscriber is taking the values which are published like a 20 seconds or 40 seconds ago, I want it to take the value in the time I making the expression

any clue ? where could be the problem

do you suggest to do that with a static transfrom publisher? or what is the best way to do it?

how to change robot's movemetns directions in the odometry frame Hello, I am trying to use the navigation stack into my

how to change robot's movemetns directions in the odometry frame Hello, I am trying to use the navigation stack into my

how to change robot's movemetns directions in the odometry frame Hello, I am trying to use the navigation stack into my

I am trying to use the rviz package to visualize the urdf I had made using a launch file

but every time I am trying to roslaunch my launch file give me this error

I have double checked every thing but the error still appear

 roslaunch mastering_ros_robot_description_pkg view_demo.launch
[view_demo.launch] is neither a launch file in package [mastering_ros_robot_description_pkg] nor is [mastering_ros_robot_description_pkg] a launch file name
The traceback for the exception was written to the log file

mavros disarm whenever publishing to rc/override Hello, I am using mavros installed on a laptop and I have my pixhawk c

problem configuring robot localization Hello, I am trying to use the robot localization package into my underwater rob

Actually I don't have that much experience on how to configure covariances

shall I show you another IMU msg you mean?

The IMU gives orientation, linear acceleration, and angular velocity in my case. The thing is I can not provide odometr

[robot_localization] high pose drift with only IMU data Hello, I am trying to make use of the robot_localization packag

I couldn't find a solution unfortunately. But it works fine on Ubuntu 16.04

Hello,

I am building a differential drive robot and I want to exploit the power of the diff_drive_controller

but I have faced a couple of problems to interface my hardware to the controller I am using a tiva c launchpad as my embedded board but the real problem is, where can I get the velocity output of each wheel from the controller then I can transfer it with the appropriate method to the motors?

Hello I am building a differential drive robot using differential_drive package and rosserial_tivac to interface with my hardware I have written my codes and iclude them all in one launch file when i use roslaunch every thing is working fine and the following message appear in terminal

process[rosout-1]: started with pid [11918]
started core service [/rosout]
process[serial_gate_node-2]: started with pid [11935]
process[lpid_velocity-3]: started with pid [11936]
process[rpid_velocity-4]: started with pid [11937]
process[twist_to_motors-5]: started with pid [11938]
[INFO] [1534898274.948213]: ROS Serial Python Node
[INFO] [1534898274.952975]: Connecting to /dev/ttyACM0 at 57600 baud
[INFO] [1534898274.997246]: /twist_to_motors started
[INFO] [1534898277.081039]: Note: publish buffer size is 512 bytes
[INFO] [1534898277.081769]: Setup publisher on lwheel [std_msgs/Int16]
[INFO] [1534898277.093732]: Setup publisher on rwheel [std_msgs/Int16]
[INFO] [1534898277.111318]: Note: subscribe buffer size is 512 bytes
[INFO] [1534898277.112105]: Setup subscriber on lmotor_cmd [std_msgs/Float32]
[INFO] [1534898277.126081]: Setup subscriber on rmotor_cmd [std_msgs/Float32]

Then when I try to publish a msg to the topic /twist that supposes to drive the robot. The motors start operating in the right direction but with a full speed which possibly means they didn't get the proper PWM value and I am getting the following info appearing on my terminal

[INFO] [1534898288.361617]: wrong checksum for topic id and msg
[ERROR] [1534898302.098102]: Lost sync with device, restarting...

the codes witch I am using is from this repository if any one can help please