How can I simulate Ackermann steering in Gazebo? [closed]

asked 2011-03-19 10:30:04 -0600

792 ●17 ●29 ●39

updated 2014-01-28 17:09:22 -0600

ngrennan
1 ●1 ●1

I have created a URDF file that describes a vehicle with Ackermann steering (a Traxxas E-Maxx RC truck) and need to simulate the vehicle in Gazebo. To simulate Ackermann steering, I am considering writing a Gazebo controller plug-in like this:

ackermann_steering_controller:
    leftJointName (string)
    rightJointName (string)
    track (float)
    wheelbase (float)

The controller would subscribe to messages from joy_node, getting the steering angle from it, then would perform PID servo control on the left and right joints to keep them rotated to angles that satisfy the Ackermann equation. Is there a better way to do this? I've read the transmission tutorials, but haven't been able to figure out how to adapt the PR2 transmission system to a Gazebo simulation of Ackermann steering.

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Closed for the following reason the question is answered, right answer was accepted by Jim Rothrock
close date 2015-08-24 17:57:43.368036

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I haven't done anything related to this, but you may be able to check out the Gazebo model for the ClodBuster. It's a 4-wheel Ackerman robot.

mjcarroll ( 2011-03-20 11:09:46 -0600 )edit

I would like to use gazebo for an autonomous car with Ackermann steering. Please keep everyone posted on what you do.

joq ( 2011-03-25 15:35:50 -0600 )edit

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answered 2011-03-25 20:40:29 -0600

hsu
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updated 2011-03-25 20:45:01 -0600

One way is the implement the 4 bar linkage. Here's a simple model constructed with 4 bar linkage steering mechanism. I did not compute the exact linkage lengths for Ackermann steering, but the basic idea is there:

  <robot
        xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz"
        xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model"
        xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor"
        xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body"
        xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom"
        xmlns:joint="http://playerstage.sourceforge.net/gazebo/xmlschema/#joint"
        xmlns:controller="http://playerstage.sourceforge.net/gazebo/xmlschema/#controller"
        xmlns:interface="http://playerstage.sourceforge.net/gazebo/xmlschema/#interface"
        xmlns:rendering="http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering"
        xmlns:physics="http://playerstage.sourceforge.net/gazebo/xmlschema/#physics"
        name="ackermann">

    <property name="M_PI" value="3.1415926535897931" />

    <link name="base">
      <inertial>
        <mass value="1.0" />
        <origin xyz="0 0 0" /> 
        <inertia  ixx="1.0" ixy="0.0"  ixz="0.0"  iyy="1.0"  iyz="0.0"  izz="1.0" />
      </inertial>
      <visual>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <box size="2.0 1.0 0.1" />
        </geometry>
      </visual>
      <collision>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <box size="2.0 1.0 0.1" />
        </geometry>
      </collision>
    </link>
    <gazebo reference="base">
      <material>Gazebo/Blue</material>
      <turnGravityOff>false</turnGravityOff>
    </gazebo>

    <link name="front_left_bar">
      <inertial>
        <mass value="1.0" />
        <origin xyz="0 0 0" /> 
        <inertia  ixx="1.0" ixy="0.0"  ixz="0.0"  iyy="1.0"  iyz="0.0"  izz="1.0" />
      </inertial>
      <visual>
        <origin xyz="-0.2 -0.2 0" rpy="0 0 0" />
        <geometry>
          <box size="0.4 0.5 0.01" />
        </geometry>
      </visual>
      <collision>
        <origin xyz="-0.2 -0.2 0" rpy="0 0 0" />
        <geometry>
          <box size="0.4 0.5 0.01" />
        </geometry>
      </collision>
    </link>
    <gazebo reference="front_left_bar">
      <material>Gazebo/Green</material>
      <turnGravityOff>false</turnGravityOff>
    </gazebo>
    <joint name="front_left_bar_joint" type="revolute" >
      <limit lower="-0.2" upper="0.2" effort="100" velocity="10" />
      <axis xyz="0 0 1" />
      <parent link="base" />
      <child link="front_left_bar" />
      <origin xyz="1.0 0.5 0.055" rpy="0 0 0" />
    </joint>

    <link name="front_right_bar">
      <inertial>
        <mass value="1.0" />
        <origin xyz="0 0 0" /> 
        <inertia  ixx="1.0" ixy="0.0"  ixz="0.0"  iyy="1.0"  iyz="0.0"  izz="1.0" />
      </inertial>
      <visual>
        <origin xyz="-0.2 0.2 0" rpy="0 0 0" />
        <geometry>
          <box size="0.4 0.5 0.01" />
        </geometry>
      </visual>
      <collision>
        <origin xyz="-0.2 0.2 0" rpy="0 0 0" />
        <geometry>
          <box size="0.4 0.5 0.01" />
        </geometry>
      </collision>
    </link>
    <gazebo reference="front_right_bar">
      <material>Gazebo/Green</material>
      <turnGravityOff>false</turnGravityOff>
    </gazebo>
    <joint name="front_right_bar_joint" type="revolute" >
      <limit lower="-0.2" upper="0.2" effort="100" velocity="10" />
      <axis xyz="0 0 1" />
      <parent link="base" />
      <child link="front_right_bar" />
      <origin xyz="1.0 -0.5 0.055" rpy="0 0 0" />
    </joint>

    <link name="front_left_wheel">
      <inertial>
        <mass value="1.0" />
        <origin xyz="0 0 0" /> 
        <inertia ...

(more)

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adjusting the 4 bar linkage lengths so the 4 bar linkage enforces Ackermann steering. After that you still need a transmission to control one of the linkage joints using a pr2_controllers if you wish.

hsu ( 2011-03-25 20:44:02 -0600 )edit

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How can I simulate Ackermann steering in Gazebo? [closed]

Closed for the following reason the question is answered, right answer was accepted by Jim Rothrock
close date 2015-08-24 17:57:43.368036

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How can I simulate Ackermann steering in Gazebo? [closed] edit

Closed for the following reason the question is answered, right answer was accepted by Jim Rothrock close date 2015-08-24 17:57:43.368036

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How can I simulate Ackermann steering in Gazebo? [closed]

Closed for the following reason the question is answered, right answer was accepted by Jim Rothrock
close date 2015-08-24 17:57:43.368036