My robot explodes after sending msgs to the wheels in the gazebo

asked 2020-11-20 12:24:10 -0600

al_ca gravatar image

updated 2020-11-21 05:42:16 -0600

Hello there,

I have a robot with a triangular form chassis and three 120 degrees each omniwheel apart.

I have built the urdf of my robot and I separated my omniwheel into two parts the rim and the roller(s).

I have approx calculated the inertia of each part. Also when I ran the teleop_keypoard and I move it forward the value of the topic for instance right_joint_velocity_controller/command is approx 11.32(S.I.= ? I suppose its rad/s). I think that the problem is in the PID values, if so how can I configure these values?

I have putted this transmission tag in my rim joints:

    <transmission name="rim_${name}_transmission">

        <type>transmission_interface/SimpleTransmission</type>
        <joint name="rim_${name}_joint">

            <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>

        </joint>
        <actuator name="rim_${name}_motor">

            <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
            <mechanicalReduction>1</mechanicalReduction>

        </actuator>

    </transmission>

and the yaml file:

demo_DIR:

joint_state_controller:
    type: joint_state_controller/JointStateController
    publish_rate: 50

left_joint_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint: rim_left_joint
    pid: {p: 0.05, i: 0.1, d: 0.0}

back_joint_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint: rim_back_joint
    pid: {p: 0.05, i: 0.1, d: 0.0}

right_joint_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint: rim_right_joint
    pid: {p: 0.05, i: 0.1, d: 0.0}
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Comments

what do you mean by explodes?

chfritz gravatar image chfritz  ( 2020-11-20 13:49:04 -0600 )edit

It starts to fly and the parts(links) are ripped apart, after I send a command to the wheels with values up 1.5 m/s from teleop

al_ca gravatar image al_ca  ( 2020-11-20 14:33:44 -0600 )edit

oh, you must mean in simulation! That wasn't clear from your question. Sounds more like a simulation error to me than a control issue.

chfritz gravatar image chfritz  ( 2020-11-20 15:33:59 -0600 )edit

haha sorry for that... I will update my question. So that means I can't fix it?

al_ca gravatar image al_ca  ( 2020-11-21 05:39:11 -0600 )edit

I've seen it before but don't have a good understanding what is causing it. I seem to remember that sometimes it can be "fixed" by adjusting the real-time factor of gazebo. I'm almost certain that you'll find existing questions and answers for this though, if you specifically look for simulations going wild.

chfritz gravatar image chfritz  ( 2020-11-22 12:32:42 -0600 )edit