mizu_lily's profile - activity

I am dealing with NI PCI-6224. It works when using the Comedi driver on Qt for Linux. Comedi reference here So I suppose writing a node with Comedi may help. Yet I haven't tried and worked everything out.

I have the same problem. I have a three-link planar which can only move on a plane. After setting up MoveIt pkg, I can't update the start state to current state. That means the trajectory it plans is always from all zeros and the robot moves back first then follows trajectory in every execution.

I always get an error that the joint I want to cope with does not exist. Did you have the same problem before? And can you tell me how you define the inertial parameters to get a right measurement? Thanks a lot!

I think the key problem is that the example of rrbot uses a hardware interface of joint effort. If you want to implement MoveIt to it, you need to build a joint trajectory controller.

• Add a trajectory controller to your robot:

rrbot_control/config/rrbot_control.yaml

arm_controller:
type: effort_controllers/JointTrajectoryController
joints:
   - joint1
   - joint2
constraints:
    goal_time: 0.0
    stopped_velocity_tolerance: 0.01
    joint1: {trajectory: 0.01, goal: 0.01}
    joint2: {trajectory: 0.01, goal: 0.01}
gains:
   joint1: {p: 100.0, d: 75.0, i: 0.0, i_clamp: 0.0}
   joint2: {p: 100.0, d: 25.0, i: 0.0, i_clamp: 0.0}
state_publish_rate:  100
action_monitor_rate: 100
stop_trajectory_duration: 0.0

notice that you should maunally setup these parameters to have a good performance, especially pid.

• Remap the controller topic to MoveIt topic

  rrbot_gazebo/launch/rrbot_world.launch

  <remap from="/rrbot/arm_controller/follow_joint_trajectory" to="/joint_trajectory_action"/> <remap from="/rrbot/arm_controller/state" to="/feedback_states"/> <remap from="/rrbot/arm_controller/command" to="/joint_path_command"/>

If you just want to learn how to set-up MoveIt with a simple robot, I suggest you change the hardware interface to joint position interface. It's at the bottom of the description of rrbot. Tag hardwareInterface of joint and actuator both should be PositionJointInterface. And then in the joint trajectory controller, you don't have to tune pid any more.

Hope this would help.