Hi, I'd like to write a publisher node that outputs messages of type JointState and then is read by rviz2, displaying the moving joints of my robot onto its display. I followed the nav2 docs up to this stage which go through how to use the jointstatepublishergui to move the joints in rviz2. This worked correctly and it seemed as if these messaged were being published onto the /jointstates topic as when I echoed them into my terminal it was displaying messages that made sense.

My logic was to then write a publisher node as seen below, that would publish messages of type JointState, onto the /joint_state topic and that would cause rviz2 to show the movement. I made the node and it seemed to work, as again, when I echoed it into another terminal it was displaying the correct messages, however the joints of my robot on rviz2 was not showing any movement.

Have I made an error in judgement, or is my code incorrect?

Publisher node:

> #!/usr/bin/env python3
> 
> import rclpy import math from
> rclpy.node import Node import random
> 
> from sensor_msgs.msg import JointState
> 
> 
> class MinimalPublisher(Node):
> 
>     def __init__(self):
>         super().__init__('joint_publisher')
>         self.publisher_ = self.create_publisher(JointState,
> 'joint_states', 10)
>         timer_period = 2  # seconds
>         self.timer = self.create_timer(timer_period,
> self.timer_callback)
>         self.i = 0.0
> 
>     def timer_callback(self):
>         msg = JointState()
>         msg.name = ['shoulder_fr_twist_joint',
> 'shoulder_fl_twist_joint',
> 'shoulder_br_twist_joint',
> 'shoulder_bl_twist_joint',
> 'shoulder_fr_joint',
> 'shoulder_fl_joint',
> 'shoulder_br_joint',
> 'shoulder_bl_joint',
> 'forearm_fr_joint',
> 'forearm_fl_joint',
> 'forearm_br_joint',
> 'forearm_bl_joint']
>         # pick random int between the limits
>         msg.position = [random.uniform(-0.4, 0.4),
> random.uniform(-0.4, 0.4),
> random.uniform(-0.4, 0.4),
> random.uniform(-0.4, 0.4),
> random.uniform(-0.8, 0.8),
> random.uniform(-0.8, 0.8),
> random.uniform(-0.8, 0.8),
> random.uniform(-0.8, 0.8),
> random.uniform(-0.8, 1),
> random.uniform(-0.8, 1),
> random.uniform(-0.8, 1),
> random.uniform(-0.8, 1)]
>         msg.velocity = []
>         msg.effort = []
>         
>         self.publisher_.publish(msg)
>         self.get_logger().info('Publishing:
> "%s"' % self.i)
>         self.i += 0.1
> 
> 
> def main(args=None):
>     rclpy.init(args=args)
> 
>     minimal_publisher = MinimalPublisher()
> 
>     rclpy.spin(minimal_publisher)
> 
>     # Destroy the node explicitly
>     # (optional - otherwise it will be done automatically
>     # when the garbage collector destroys the node object)
>     minimal_publisher.destroy_node()
>     rclpy.shutdown()
> 
> 
> if __name__ == '__main__':
>     main()

Please let me know if you would like any further information, I've been stuck on this for a few days and would love for this to be cleared up!

[joint_publisher] -> (/joint_states) -> [rviz]

[joint_publisher] -> (/joint_states) -> [robot_state_publisher] -> (/tf, /tf_static, /robot_description)) -> [rviz]