Real robot lab very slow

[igor.barsanti]

Hi, I tried for the first time turtlebot real robot lab the robot get commands for line 2/3 seconds, then stop, if i relaunch my node, the robot restart, move for 2/3 seconds, then suddendly stop…
The same code work without problema in simulation…

Thanks,
Igor

[roalgoal]

Hi, welcome to the community!

Did the same issue happen when you moved it around with the joystick?

The robot has a velocity limit for safety, so that might explain the stopping. Try using a linear velocity lower than 0.15.

[igor.barsanti]

When I use the joystick the movement is continuous, when I use my node the robot advance for a few centimeters, stop, wait, then restart. The robot follows the programmed path, but with a stop and go pace…

this is my node code (it’s ros2, but I launch ros1 bridge…):

import rclpy

from rclpy.node import Node

from geometry_msgs.msg import Twist

from sensor_msgs.msg import LaserScan

class WallController(Node):

    x = 0 

    z = 0

    def __init__(self):

        super().__init__('WallController')

        self.publisher_cmd_vel = self.create_publisher(Twist, 'cmd_vel', 10)

        self.subscriber_scan = self.create_subscription(LaserScan, 'scan', self.scan_callback, 10)

        self.publisher_cmd_vel

        self.subscriber_scan

    def move(self,x,z):

        msg = Twist()

        self.x = x

        self.z = z

        msg.linear.x = self.x

        msg.angular.z = self.z

        self.publisher_cmd_vel.publish(msg)  

    def scan_callback(self, msg):

        steps = (msg.angle_max - msg.angle_min)/msg.angle_increment 

        right_step = int(steps / 4.0 * 1.0)

        front_step = int(steps / 2.0)

        self.get_logger().info('STEPS: %f,%f %f' % (steps, front_step, front_step))

        right_wall_distance = msg.ranges[right_step]

        front_wall_distance = msg.ranges[front_step]        

        if front_wall_distance < 0.6:

            self.move(0.0, 0.48)

        else:

            if right_wall_distance < 0.5:

                self.move(0.10, 0.15)              

            elif right_wall_distance >= 0.5 and right_wall_distance < 0.6:

                self.move(0.14, 0.0)

            else:

                self.move(0.10, -0.15)

        self.get_logger().info('%f,%f %f:%f' % (front_wall_distance, right_wall_distance, self.x, self.z))

def main(args=None):

    rclpy.init(args=args)

    wall_controller = WallController()

    rclpy.spin(wall_controller)

    wall_controller.destroy_node()

    

    rclpy.shutdown()

if __name__ == '__main__':

    main()

[roalgoal]

Have you tried spinning your node at a faster rate? Maybe the publishing needs to be faster.

Here is some info that can be useful:

https://answers.ros.org/question/358343/rate-and-sleep-function-in-rclpy-library-for-ros2/