Solve the problem that all joints of the xArm are at '0' in the gazebo

Examples are valid for:

ROS version: Kinetic
Ubuntu version: ubuntu-16.04

This problem is shown in the figure.

When executing "roslaunch xarm_gazebo xarm6_beside_table.launch run_demo: = true", all joints of the UFACTORY xArm are at 0 in the gazebo.

Solutions

● Comment out the Pid parameter of the joint under the gazebo_ros_control module in the xarm6_traj_controller file.
● Comment out the Pid parameter of the joint under the gazebo_ros_control module in the xarm6_position_controllers file.
● Save the xarm6_traj_controller.yaml and the xarm6_position_controllers.yaml

The directory of the xarm6_traj_controller file: src/xarm_controller/config/xarm6_traj_controller.yaml

xarm:    
  joint_state_controller:      
  type: joint_state_controller/JointStateController      
  publish_rate: 50 
         
xarm6_traj_controller:      
  type: position_controllers/JointTrajectoryController      
  joints:         
     - joint1         
     - joint2         
     - joint3         
     - joint4         
     - joint5         
     - joint6      
constraints:          
  goal_time: 0.5          
  stopped_velocity_tolerance: 0.05          
  joint1: {trajectory: 1, goal: 0.01}          
  joint2: {trajectory: 1, goal: 0.01}          
  joint3: {trajectory: 1, goal: 0.01}          
  joint4: {trajectory: 1, goal: 0.01}          
  joint5: {trajectory: 1, goal: 0.01}          
  joint6: {trajectory: 1, goal: 0.01}      
stop_trajectory_duration: 0.2      
state_publish_rate:  25      
action_monitor_rate: 10      

# No Pid gains specified error fix    
# gazebo_ros_control:    
#   pid_gains:    
#     joint1: {p: 1200.0, i: 5.0, d: 10.0}    
#     joint2: {p: 1400.0, i: 5.0, d: 10.0}    
#     joint3: {p: 1200.0, i: 5.0, d: 5.0}    
#     joint4: {p: 850.0, i: 3.0, d: 5.0}    
#     joint5: {p: 500.0, i: 3.0, d: 1.0}    
#     joint6: {p: 500.0, i: 1.0, d: 1.0}

The directory of the xarm6_position_controllers file: src/xarm_controller/config/xarm6_position_controllers.yaml

xarm: 
# Publish all joint states ----------------------------------- joint_state_controller: 
type: joint_state_controller/JointStateController 
publish_rate: 50 

# Position Controllers --------------------------------------- joint1_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint1 
  pid: {p: 1200.0, i: 5.0, d: 10.0} 
joint2_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint2 
  pid: {p: 1400.0, i: 5.0, d: 10.0} 
joint3_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint3 
  pid: {p: 1200.0, i: 5.0, d: 5.0} 
joint4_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint4 
  pid: {p: 850.0, i: 3.0, d: 5.0} 
joint5_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint5 
  pid: {p: 500.0, i: 3.0, d: 1.0} 
joint6_position_controller: 
  type: position_controllers/JointPositionController 
  joint: joint6 
  pid: {p: 500.0, i: 1.0, d: 1.0} 

# No Pid gains specified error fix 
# gazebo_ros_control: 
# pid_gains: 
# joint1: {p: 1200.0, i: 5.0, d: 10.0} 
# joint2: {p: 1400.0, i: 5.0, d: 10.0} 
# joint3: {p: 1200.0, i: 5.0, d: 5.0} 
# joint4: {p: 850.0, i: 3.0, d: 5.0} 
# joint5: {p: 500.0, i: 3.0, d: 1.0} 
# joint6: {p: 500.0, i: 1.0, d: 1.0}

● After the problem is solved, execute the following commands, xArm will move normally in gazebo, see the following video.

source devel/set.bash
roslaunch xarm_gazebo xarm6_beside_table.launch run_demo:=true