I modeled my physical, simple diff-drive robot with two larger drive wheels and two casters. The robot total weight is around 30 kg. Body size is L=0.512 m, W=0.384 m , H=0.211 m
When I interact with the model (Apply Force/Torque) in Gazebo, I need to use very large forces to move it: 10 kN barely moves it, 100 kN pushes it around 1 m forward. The force feels completely disproportional.
Is there anything wrong with my model because this does not pass a smell test?
Appreciate any feedback.
The body inertial is as follows:
<inertial>
<mass value="30.0"/>
<inertia ixx="0.7666624999999999" ixy="0.0" ixz="0.0" iyy="1.024" iyz="0.0" izz="0.47994250000000005"/>
</inertial>
The entire URDF:
<?xml version="1.0" ?>
<!-- =================================================================================== -->
<!-- | This document was autogenerated by xacro from travik.xacro | -->
<!-- | EDITING THIS FILE BY HAND IS NOT RECOMMENDED | -->
<!-- =================================================================================== -->
<robot name="travik">
<material name="black">
<color rgba="0.0 0.0 0.0 1.0"/>
</material>
<material name="blue">
<color rgba="0.0 0.0 0.8 1.0"/>
</material>
<material name="green">
<color rgba="0.0 0.8 0.0 1.0"/>
</material>
<material name="grey">
<color rgba="0.2 0.2 0.2 1.0"/>
</material>
<material name="orange">
<color rgba="1.0 0.4235294117647059 0.0392156862745098 1.0"/>
</material>
<material name="brown">
<color rgba="0.8705882352941177 0.8117647058823529 0.7647058823529411 1.0"/>
</material>
<material name="red">
<color rgba="0.8 0.0 0.0 1.0"/>
</material>
<material name="white">
<color rgba="1.0 1.0 1.0 1.0"/>
</material>
<!-- https://en.wikipedia.org/wiki/List_of_moments_of_inertia#List_of_3D_inertia_tensors -->
<!-- prevent "The root base_link has an inertia specified in the URDF, but KDL" error -->
<link name="base_footprint"/>
<joint name="base_joint" type="fixed">
<parent link="base_footprint"/>
<child link="base_link"/>
<origin rpy="0 0 0" xyz="0.0 0.0 0.010"/>
</joint>
<link name="base_link">
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<box size="0.512 0.384 0.211"/>
</geometry>
<material name="green"/>
</visual>
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<box size="0.512 0.384 0.211"/>
</geometry>
</collision>
<inertial>
<mass value="30.0"/>
<inertia ixx="0.7666624999999999" ixy="0.0" ixz="0.0" iyy="1.024" iyz="0.0" izz="0.47994250000000005"/>
</inertial>
</link>
<link name="left_front_wheel">
<visual>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.083" radius="0.128"/>
</geometry>
<material name="black"/>
</visual>
<collision>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.083" radius="0.128"/>
</geometry>
</collision>
<inertial>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<mass value="3"/>
<inertia ixx="0.01401025" ixy="0" ixz="0" iyy="0.01401025" iyz="0" izz="0.024576"/>
</inertial>
</link>
<joint name="left_front_wheel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 1 0"/>
<parent link="base_link"/>
<child link="left_front_wheel"/>
<origin rpy="0 0 0" xyz="0.128 0.2495 -0.04149999999999998"/>
<dynamics damping="0.7"/>
</joint>
<link name="right_front_wheel">
<visual>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.083" radius="0.128"/>
</geometry>
<material name="black"/>
</visual>
<collision>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.083" radius="0.128"/>
</geometry>
</collision>
<inertial>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<mass value="3"/>
<inertia ixx="0.01401025" ixy="0" ixz="0" iyy="0.01401025" iyz="0" izz="0.024576"/>
</inertial>
</link>
<joint name="right_front_wheel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 1 0"/>
<parent link="base_link"/>
<child link="right_front_wheel"/>
<origin rpy="0 0 0" xyz="0.128 -0.2495 -0.04149999999999998"/>
<dynamics damping="0.7"/>
</joint>
<!-- caster -->
<!-- caster_swivel -->
<!-- caster wheel -->
<link name="left_rear_caster_swivel">
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.125" radius="0.0125"/>
</geometry>
<material name="blue"/>
</visual>
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.125" radius="0.0125"/>
</geometry>
</collision>
<inertial>
<origin rpy="0 0 0" xyz="0 0 0"/>
<mass value="1"/>
<inertia ixx="0.0013411458333333333" ixy="0" ixz="0" iyy="0.0013411458333333333" iyz="0" izz="7.812500000000002e-05"/>
</inertial>
<dynamics damping="0.7"/>
</link>
<joint name="left_rear_swivel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 0 1"/>
<parent link="base_link"/>
<child link="left_rear_caster_swivel"/>
<origin rpy="0 0 0" xyz="-0.256 0.192 0"/>
</joint>
<link name="left_rear_caster_wheel">
<visual>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.051" radius="0.0895"/>
</geometry>
<material name="black"/>
</visual>
<collision>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.051" radius="0.0895"/>
</geometry>
</collision>
<inertial>
<origin rpy="0 0 0" xyz="0 0 0"/>
<mass value="1"/>
<inertia ixx="0.0022193124999999995" ixy="0" ixz="0" iyy="0.0022193124999999995" iyz="0" izz="0.004005125"/>
</inertial>
</link>
<joint name="left_rear_wheel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 1 0"/>
<parent link="left_rear_caster_swivel"/>
<child link="left_rear_caster_wheel"/>
<origin rpy="0 0 0" xyz="-0.04475 0 -0.07999999999999999"/>
<dynamics damping="0.7"/>
</joint>
<!-- caster_swivel -->
<!-- caster wheel -->
<link name="right_rear_caster_swivel">
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.125" radius="0.0125"/>
</geometry>
<material name="blue"/>
</visual>
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.125" radius="0.0125"/>
</geometry>
</collision>
<inertial>
<origin rpy="0 0 0" xyz="0 0 0"/>
<mass value="1"/>
<inertia ixx="0.0013411458333333333" ixy="0" ixz="0" iyy="0.0013411458333333333" iyz="0" izz="7.812500000000002e-05"/>
</inertial>
<dynamics damping="0.7"/>
</link>
<joint name="right_rear_swivel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 0 1"/>
<parent link="base_link"/>
<child link="right_rear_caster_swivel"/>
<origin rpy="0 0 0" xyz="-0.256 -0.192 0"/>
</joint>
<link name="right_rear_caster_wheel">
<visual>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.051" radius="0.0895"/>
</geometry>
<material name="black"/>
</visual>
<collision>
<origin rpy="1.5707963267948966 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.051" radius="0.0895"/>
</geometry>
</collision>
<inertial>
<origin rpy="0 0 0" xyz="0 0 0"/>
<mass value="1"/>
<inertia ixx="0.0022193124999999995" ixy="0" ixz="0" iyy="0.0022193124999999995" iyz="0" izz="0.004005125"/>
</inertial>
</link>
<joint name="right_rear_wheel_joint" type="continuous">
<axis rpy="0 0 0" xyz="0 1 0"/>
<parent link="right_rear_caster_swivel"/>
<child link="right_rear_caster_wheel"/>
<origin rpy="0 0 0" xyz="-0.04475 0 -0.07999999999999999"/>
<dynamics damping="0.7"/>
</joint>
<!-- Size of square 'camera' box -->
<joint name="camera_joint" type="fixed">
<axis xyz="0 1 0"/>
<origin rpy="0 0 0" xyz="0.256 0 0.06799999999999999"/>
<parent link="base_link"/>
<child link="camera_link"/>
</joint>
<!-- Camera -->
<link name="camera_link">
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<box size="0.05 0.05 0.05"/>
</geometry>
</collision>
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<box size="0.05 0.05 0.05"/>
</geometry>
<material name="red"/>
</visual>
<inertial>
<mass value="1e-5"/>
<origin rpy="0 0 0" xyz="0 0 0"/>
<inertia ixx="1e-6" ixy="0" ixz="0" iyy="1e-6" iyz="0" izz="1e-6"/>
</inertial>
</link>
<!-- generate an optical frame http://www.ros.org/reps/rep-0103.html#suffix-frames
so that ros and opencv can operate on the camera frame correctly -->
<joint name="camera_optical_joint" type="fixed">
<!-- these values have to be these values otherwise the gazebo camera image
won't be aligned properly with the frame it is supposedly originating from -->
<origin rpy="-1.5707963267948966 0 -1.5707963267948966" xyz="0 0 0"/>
<parent link="camera_link"/>
<child link="camera_link_optical"/>
</joint>
<link name="camera_link_optical"/>
<!-- Size of 'laser' -->
<joint name="laser_joint" type="fixed">
<axis xyz="0 1 0"/>
<origin rpy="0 0 0" xyz="0.128 0 0.1255"/>
<parent link="base_link"/>
<child link="laser_link"/>
</joint>
<!-- laser -->
<link name="laser_link">
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.04" radius="0.02"/>
</geometry>
</collision>
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<cylinder length="0.04" radius="0.02"/>
</geometry>
<material name="red"/>
</visual>
<inertial>
<mass value="1e-5"/>
<origin rpy="0 0 0" xyz="0 0 0"/>
<inertia ixx="1e-6" ixy="0" ixz="0" iyy="1e-6" iyz="0" izz="1e-6"/>
</inertial>
</link>
<!-- ros_control plugin -->
<gazebo>
<plugin filename="libgazebo_ros_control.so" name="gazebo_ros_control">
<robotNamespace>/travik</robotNamespace>
<robotSimType>gazebo_ros_control/DefaultRobotHWSim</robotSimType>
</plugin>
</gazebo>
<!-- Friction coefficients
https://www.engineeringtoolbox.com/friction-coefficients-d_778.html -->
<gazebo reference="base_link">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Green</material>
</gazebo>
<gazebo reference="body_link">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Green</material>
</gazebo>
<gazebo reference="left_front_wheel">
<mu1>0.2</mu1>
<!-- 0.9 rubber on dry asphalt -->
<mu2>0.2</mu2>
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="right_front_wheel">
<mu1>0.9</mu1>
<!-- rubber on dry asphalt -->
<mu2>0.2</mu2>
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="left_rear_caster_swivel">
<mu1>0.9</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="right_rear_caster_swivel">
<mu1>0.2</mu1>
<mu2>0.2</mu2>
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="left_rear_caster_wheel">
<mu1>0.9</mu1>
<!-- rubber on dry asphalt -->
<mu2>0.2</mu2>
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="right_rear_caster_wheel">
<mu1>0.9</mu1>
<!-- rubber on dry asphalt -->
<mu2>0.2</mu2>
<material>Gazebo/Black</material>
</gazebo>
<!-- Inno LD06 LIDAR-->
<gazebo reference="laser_link">
<sensor name="head_laser" type="gpu_ray">
<pose>0.128 0 0 0 0 0</pose>
<visualize>false</visualize>
<update_rate>40</update_rate>
<ray>
<scan>
<horizontal>
<samples>720</samples>
<resolution>1</resolution>
<min_angle>-3.14159</min_angle>
<max_angle>3.14159</max_angle>
</horizontal>
</scan>
<range>
<min>0.05</min>
<max>12.0</max>
<resolution>0.01</resolution>
</range>
<noise>
<type>gaussian</type>
<!-- Noise parameters based on published spec for Hokuyo laser
achieving "+-30mm" accuracy at range < 10m. A mean of 0.0m and
stddev of 0.01m will put 99.7% of samples within 0.03m of the true
reading. -->
<mean>0.0</mean>
<stddev>0.01</stddev>
</noise>
</ray>
-
<plugin filename="libgazebo_ros_gpu_laser.so" name="gazebo_ros_head_ld06_controller">
<topicName>/scan</topicName>
<frameName>laser_link</frameName>
</plugin>
</sensor>
</gazebo>
<!-- camera -->
<gazebo reference="camera_link">
<sensor name="head_camera" type="camera">
<update_rate>30.0</update_rate>
<camera name="head">
<horizontal_fov>1.3962634</horizontal_fov>
<image>
<width>800</width>
<height>800</height>
<format>R8G8B8</format>
</image>
<clip>
<near>0.02</near>
<far>300</far>
</clip>
<noise>
<type>gaussian</type>
<!-- Noise is sampled independently per pixel on each frame.
That pixel's noise value is added to each of its color
channels, which at that point lie in the range [0,1]. -->
<mean>0.0</mean>
<stddev>0.007</stddev>
</noise>
</camera>
<plugin filename="libgazebo_ros_camera.so" name="camera_controller">
<alwaysOn>true</alwaysOn>
<updateRate>0.0</updateRate>
<cameraName>/travik/camera1</cameraName>
<imageTopicName>image_raw</imageTopicName>
<cameraInfoTopicName>camera_info</cameraInfoTopicName>
<frameName>camera_link_optical</frameName>
<!-- setting hackBaseline to anything but 0.0 will cause a misalignment
between the gazebo sensor image and the frame it is supposed to
be attached to -->
<hackBaseline>0.0</hackBaseline>
<distortionK1>0.0</distortionK1>
<distortionK2>0.0</distortionK2>
<distortionK3>0.0</distortionK3>
<distortionT1>0.0</distortionT1>
<distortionT2>0.0</distortionT2>
<CxPrime>0</CxPrime>
<Cx>0.0</Cx>
<Cy>0.0</Cy>
<focalLength>0.0</focalLength>
</plugin>
</sensor>
</gazebo>
<gazebo>
<plugin filename="libgazebo_ros_diff_drive.so" name="differential_drive_controller">
<alwaysOn>false</alwaysOn>
<!-- Plugin update rate in Hz -->
<updateRate>20</updateRate>
<!-- Set to true to swap right and left wheels, defaults to true -->
<legacyMode>false</legacyMode>
<!-- Name of left joint, defaults to `left_joint` -->
<leftJoint>left_front_wheel_joint</leftJoint>
<!-- Name of right joint, defaults to `right_joint` -->
<rightJoint>right_front_wheel_joint</rightJoint>
<!-- The distance from the center of one wheel to the other, in meters, defaults to 0.34 m -->
<wheelSeparation>0.083 + 0.384</wheelSeparation>
<!-- Diameter of the wheels, in meters, defaults to 0.15 m -->
<wheelDiameter>0.256</wheelDiameter>
<!-- Wheel acceleration, in rad/s^2, defaults to 0.0 rad/s^2 -->
<wheelAcceleration>1.0</wheelAcceleration>
<!-- Maximum torque which the wheels can produce, in Nm, defaults to 5 Nm -->
<wheelTorque>20</wheelTorque>
<!-- Topic to receive geometry_msgs/Twist message commands, defaults to `cmd_vel` -->
<commandTopic>/cmd_vel</commandTopic>
<!-- Topic to publish nav_msgs/Odometry messages, defaults to `odom` -->
<odometryTopic>/odom</odometryTopic>
<!-- Odometry frame, defaults to `/odom` -->
<odometryFrame>odom</odometryFrame>
<!-- Robot frame to calculate odometry from, defaults to `base_footprint` -->
<robotBaseFrame>base_footprint</robotBaseFrame>
<!-- Odometry source, 0 for ENCODER, 1 for WORLD, defaults to WORLD -->
<odometrySource>1</odometrySource>
<!-- defaults to 1 -->
<publishTF>1</publishTF>
<!-- Set to true to publish transforms for the wheel links, defaults to false -->
<publishWheelTF>true</publishWheelTF>
<!-- Set to true to publish transforms for the odometry, defaults to true -->
<publishOdom>true</publishOdom>
<!-- Set to true to publish transforms for the odometry, defaults to true -->
<publishOdomTF>true</publishOdomTF>
<!-- Set to true to publish sensor_msgs/JointState on /joint_states for the wheel joints, defaults to false -->
<publishWheelJointState>true</publishWheelJointState>
<rosDebugLevel>na</rosDebugLevel>
</plugin>
</gazebo>
</robot>
