No response from rosservice "/gazebo/get_model_state"

[ZZWang21]

Hi, experts,

I followed the code and tried to implement RL with UR5 robot. However, currently I am stuck since I cannot get the ball_pose. The rosservice "/gazebo/get_model_state" never gave a return.

The error is like this: "

service returned no response "/gazebo/get_model_state"

Traceback (most recent call last):
File "/home/walter/catkin_ws/src/ur5e_rl_training/scripts/ur5e_train_all.py", line 64, in
model.learn(total_timesteps=10000) #100000, 1000, 20221129: 100000
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/a2c/a2c.py", line 263, in learn
rollout = self.runner.run(callback)
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/common/base_class.py", line 794, in runner
self._runner = self._make_runner()
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/a2c/a2c.py", line 110, in _make_runner
return A2CRunner(self.env, self, n_steps=self.n_steps, gamma=self.gamma)
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/a2c/a2c.py", line 338, in init
super(A2CRunner, self).init(env=env, model=model, n_steps=n_steps)
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/common/runners.py", line 31, in init
self.obs[:] = env.reset()
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/stable_baselines/common/vec_env/dummy_vec_env.py", line 61, in reset
obs = self.envs[env_idx].reset()
File "/home/walter/miniconda3/envs/Robot_ur5e_ws/lib/python3.7/site-packages/gym/wrappers/time_limit.py", line 27, in reset
return self.env.reset(**kwargs)
File "/home/walter/catkin_ws/src/openai_ros/openai_ros/src/openai_ros/robot_gazebo_env.py", line 77, in reset
self._init_env_variables()
File "/home/walter/catkin_ws/src/openai_ros/openai_ros/src/openai_ros/task_envs/ur5e_move/move.py", line 233, in _init_env_variables
self.ball_pose = self.get_ball_pose()
File "/home/walter/catkin_ws/src/openai_ros/openai_ros/src/openai_ros/robot_envs/ur5e_env.py", line 261, in get_ball_pose
POSESES = POSES.pose
AttributeError: 'NoneType' object has no attribute 'pose'
"

Since it returned nothing, so there is no 'pose'.

Please help. Thanks.