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2016-12-08 05:18:22 -0500 commented answer How to turn the orientation of the Jackal Robot?

If I send move_base goals which are oriented and placed differently(backwards) to the robot, it leads to a backward movement with a rotation at the end to achieve the right orientation.

2016-12-08 05:16:00 -0500 commented answer How to turn the orientation of the Jackal Robot?

If I sent the cmd_vel with the negated direction, the simulated robot and rviz behave in the same way, but this solution is not useable with move_base goals for the later application.

2016-12-08 04:46:51 -0500 commented answer How to turn the orientation of the Jackal Robot?

I tried to rotate any joint attached to the base_link and placed them correctly (the front_left_wheel is now really at the front left position etc.), but if I now move the robot forward in rviz, the simulated robot in Gazebo moves backwards. Do you have any idea why this happens?

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2016-12-06 05:55:21 -0500 asked a question How to turn the orientation of the Jackal Robot?

Hello everybody,

We are using the Jackal robot from clearpath robotics for a project. We want to turn the default moving direction of the robot to the opposite. So the old forward direction should then be backwards. How can we achieve this?

We tried several things, but they did not work out.

Approach 1: We tried to change the base_link_joint of the urdf-model around 180°. After the turn of a coordinate frame around yaw=180°, the robot model behaves different in Rviz and Gazebo. If the model in Gazebo moves forward, the model in Rviz moves backwards.

 <joint name="base_link_joint" type="fixed">
    <origin xyz="0 0 0" rpy="0 0 ${PI}" />
    <parent link="base_link"/>
    <child link="chassis_link" />
  </joint>

The original urdf-model can be found on https://github.com/jackal/jackal/blob...

Approach 2: Turn the direction of cmd_vel. We changed the sign of the x-value of cmd_vel to move in the opposite direction. This leads to the correct movements in Gazebo and Rviz, but the robot moves in the opposite direction of the goal (which is understandable).

We also tried the modifications on the real robot, but the problems were the same.

EDIT:

I found a solution for the simulated robot by modifying the urdf: I've turned the base_link_joint around 180° and all 4 wheels also around 180°. Rviz and Gazebo behave like they should.

<joint name="base_link_joint" type="fixed">
        <origin xyz="0 0 0" rpy="0 0 ${PI}" />
        <parent link="base_link"/>
        <child link="chassis_link" />
</joint>

<xacro:wheel prefix="front_left">
    <origin xyz="${-wheelbase/2} ${-track/2} ${wheel_vertical_offset}" rpy="0 0 ${PI}" />
</xacro:wheel>

But when I want to use the same solution for the real robot. It does not change the moving direction. The model in Rviz changes when switching between different urdf-configurations, but the direction of movement stays the same.

Does anyone has an idea why this happens? And a solution how the real robot can get the same behaviour as the simulated one?

EDIT:

We did not found a working solution how to turn the orientation. We switched the configuration of the modules on top of the robot, so that we can use the default forward direction of the system.

Thank you for your help!

Greetings,

mr