Gazebo weird behavior when two objects contact - ros

Question

Hello Gazebo/ROS community on Stack Overflow, I'm trying to simulate the landing of a quadcopter on a pole using Gazebo/ROS Kinetic. However, as soon as the drone contacts the landing pole, it gets bounced away in a very unrealistic way. Both the drone and the pole have their mass, inertia, and friction defined.
A video is avaliable here:
https://youtu.be/8Iis60y5_yk
Can anyone give me a few pointers? Your help is much appreciated!
Here is the .world file:
<?xml version="1.0" ?>
<sdf version="1.4">
<world name="default">
<include>
<uri>model://ground_plane</uri>
</include>
<include>
<uri>model://sun</uri>
</include>
<!-- Only one ROS interface plugin is required per world, as any other plugin can connect a Gazebo
topic to a ROS topic (or vise versa). -->
<plugin name="ros_interface_plugin" filename="librotors_gazebo_ros_interface_plugin.so"/>
<spherical_coordinates>
<surface_model>EARTH_WGS84</surface_model>
<latitude_deg>47.3667</latitude_deg>
<longitude_deg>8.5500</longitude_deg>
<elevation>500.0</elevation>
<heading_deg>0</heading_deg>
</spherical_coordinates>
<physics type='ode'>
<ode>
<solver>
<type>quick</type>
<iters>1000</iters>
<sor>1.3</sor>
</solver>
<constraints>
<cfm>0</cfm>
<erp>0.2</erp>
<contact_max_correcting_vel>100</contact_max_correcting_vel>
<contact_surface_layer>0.001</contact_surface_layer>
</constraints>
</ode>
<max_step_size>0.01</max_step_size>
<real_time_factor>1</real_time_factor>
<real_time_update_rate>100</real_time_update_rate>
<gravity>0 0 -9.8</gravity>
</physics>
</world>
</sdf>
Here is the xacro file for the landing pole:
<?xml version="1.0"?>
<robot name="target" xmlns:xacro="http://ros.org/wiki/xacro">
<xacro:property name="pole_height" value="1.2192" />
<xacro:property name="pole_radius" value="0.05" />
<!-- cone-shaped top compatible with the drone -->
<link name="target/cone">
<inertial>
<origin xyz="0 0 0"/>
<mass value="3.0"/>
<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>
<mesh filename="package://rotors_description/meshes/cone.dae" scale="0.001 0.001 0.001" />
</geometry>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://rotors_description/meshes/cone.dae" scale="0.001 0.001 0.001" />
</geometry>
<contact_coefficients mu ="1" kp="1000" kd="1"/>
</collision>
</link>
<!-- connect cone to pole -->
<joint name="cone_to_pole" type="fixed">
<origin xyz="0 0 0.6096"/>
<parent link="target/base_link"/>
<child link="target/cone"/>
</joint>
<!-- landing pole -->
<link name="target/base_link">
<visual>
<origin xyz="0 0 0" rpy="0 0 0"/>
<geometry>
<cylinder length="${pole_height}" radius="${pole_radius}"/>
</geometry>
<material name="white">
<color rgba="1.0 1.0 1.0 1.0"/>
</material>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<cylinder length="${pole_height}" radius="${pole_radius}"/>
</geometry>
</collision>
<inertial>
<origin xyz="0 0 0"/>
<mass value="3.0"/>
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
</inertial>
</link>
<!-- april tag -->
<link name="target/tag_link">
<inertial>
<origin xyz="0 0 0"/>
<mass value="1.0"/>
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0"/>
</inertial>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<box size="1.7 1.7 0.05" />
</geometry>
<surface>
<friction>
<ode>
<mu>0.01</mu>
<mu2>0.01</mu2>
</ode>
</friction>
</surface>
</collision>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<mesh filename="package://rotors_description/meshes/pole.dae" scale="1 1 1" />
</geometry>
</visual>
</link>
<!-- connect pole to tag -->
<joint name="target/tag_joint" type="fixed">
<origin xyz="0 0 -0.6096"/>
<parent link="target/base_link"/>
<child link="target/tag_link"/>
</joint>
<!-- make the landing pole transparent for testing purposes -->
<!-- <gazebo reference="target/base_link">
<visual>
<material>
<ambient> 1.0 1.0 1.0 0.0</ambient>
<diffuse> 1.0 1.0 1.0 0.0</diffuse>
<specular>1.0 1.0 1.0 0.0</specular>
</material>
</visual>
</gazebo>
<gazebo reference="target/cone">
<visual>
<material>
<ambient> 1.0 1.0 1.0 0.0</ambient>
<diffuse> 1.0 1.0 1.0 0.0</diffuse>
<specular>1.0 1.0 1.0 0.0</specular>
</material>
</visual>
</gazebo> -->
<xacro:include filename="$(find rotors_description)/urdf/component_snippets.xacro" />
<xacro:default_imu namespace="target" parent_link="target/base_link" />
<gazebo>
<plugin name="landing_target_plugin" filename="librotors_gazebo_landing_target_plugin.so">
<robotNamespace>target</robotNamespace>
<linkName>target/base_link</linkName>
</plugin>
</gazebo>
<gazebo reference="target/base_link">
<mu1>0.00000001</mu1>
<mu2>0.00000001</mu2>
</gazebo>
</robot>
Here is the xacro file for the base of the drone:
<?xml version="1.0"?>
<!--
Copyright 2015 Fadri Furrer, ASL, ETH Zurich, Switzerland
Copyright 2015 Michael Burri, ASL, ETH Zurich, Switzerland
Copyright 2015 Mina Kamel, ASL, ETH Zurich, Switzerland
Copyright 2015 Janosch Nikolic, ASL, ETH Zurich, Switzerland
Copyright 2015 Markus Achtelik, ASL, ETH Zurich, Switzerland
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<robot xmlns:xacro="http://ros.org/wiki/xacro">
<!-- Macro for the inertia of a box -->
<xacro:macro name="box_inertia" params="x y z mass">
<inertia ixx="${0.0833333 * mass * (y*y + z*z)}" ixy="0.0" ixz="0.0"
iyy="${0.0833333 * mass * (x*x + z*z)}" iyz="0.0"
izz="${0.0833333 * mass * (x*x + y*y)}" />
</xacro:macro>
<!-- Macro for the inertial properties of a box -->
<xacro:macro name="box_inertial" params="x y z mass *origin">
<inertial>
<mass value="${mass}" />
<xacro:insert_block name="origin" />
<xacro:box_inertia x="${x}" y="${y}" z="${z}" mass="${mass}" />
</inertial>
</xacro:macro>
<!-- Main multirotor link -->
<xacro:macro name="multirotor_base_macro"
params="robot_namespace mass body_width body_height use_mesh_file mesh_file *inertia">
<link name="${robot_namespace}/base_link">
</link>
<joint name="${robot_namespace}/base_joint" type="fixed">
<origin xyz="0 0 0" rpy=" 0 0 0" />
<parent link="${robot_namespace}/base_link" />
<child link="${robot_namespace}/base_link_inertia" />
</joint>
<link name="${robot_namespace}/base_link_inertia">
<inertial>
<mass value="${mass}" /> <!-- [kg] -->
<origin xyz="0 0 0" />
<xacro:insert_block name="inertia" />
</inertial>
<visual>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<xacro:if value="${use_mesh_file}">
<mesh filename="${mesh_file}" scale="1 1 1" />
</xacro:if>
<xacro:unless value="${use_mesh_file}">
<box size="${body_width} ${body_width} ${body_height}"/> <!-- [m] [m] [m] -->
</xacro:unless>
</geometry>
</visual>
<collision>
<origin xyz="0 0 0" rpy="0 0 0" />
<geometry>
<xacro:if value="${use_mesh_file}">
<mesh filename="${mesh_file}" scale="1 1 1" />
</xacro:if>
<xacro:unless value="${use_mesh_file}">
<box size="${body_width} ${body_width} ${body_height}"/> <!-- [m] [m] [m] -->
</xacro:unless>
</geometry>
<contact_coefficients mu ="1" kp="1000" kd="1"/>
</collision>
</link>
<!-- attach multirotor_base_plugin to the base_link -->
<gazebo>
<plugin filename="librotors_gazebo_multirotor_base_plugin.so" name="multirotor_base_plugin">
<robotNamespace>${robot_namespace}</robotNamespace>
<linkName>${robot_namespace}/base_link</linkName>
<rotorVelocitySlowdownSim>${rotor_velocity_slowdown_sim}</rotorVelocitySlowdownSim>
</plugin>
</gazebo>
</xacro:macro>
<!-- Rotor joint and link -->
<xacro:macro name="vertical_rotor"
params="robot_namespace suffix direction motor_constant moment_constant parent mass_rotor radius_rotor time_constant_up time_constant_down max_rot_velocity motor_number rotor_drag_coefficient rolling_moment_coefficient color use_own_mesh mesh *origin *inertia">
<joint name="${robot_namespace}/rotor_${motor_number}_joint" type="continuous">
<xacro:insert_block name="origin" />
<axis xyz="0 0 1" />
<!-- TODO(ff): not currently set because it's not yet supported -->
<!-- <limit effort="2000" velocity="${max_rot_velocity}" /> -->
<parent link="${parent}" />
<child link="${robot_namespace}/rotor_${motor_number}" />
</joint>
<link name="${robot_namespace}/rotor_${motor_number}">
<inertial>
<mass value="${mass_rotor}" /> <!-- [kg] -->
<xacro:insert_block name="inertia" />
</inertial>
<visual>
<geometry>
<!-- <cylinder length="0.005" radius="${radius_rotor}"/> --> <!-- [m] -->
<xacro:if value="${use_own_mesh}">
<mesh filename="${mesh}"
scale="1 1 1" />
</xacro:if>
<xacro:unless value="${use_own_mesh}">
<mesh filename="package://rotors_description/meshes/propeller_${direction}.dae"
scale="${radius_rotor} ${radius_rotor} ${radius_rotor}" /> <!-- The propeller meshes have a radius of 1m -->
<!-- <box size="${2*radius_rotor} 0.01 0.005"/> -->
</xacro:unless>
</geometry>
</visual>
<collision>
<geometry>
<cylinder length="0.005" radius="${radius_rotor}" /> <!-- [m] -->
</geometry>
</collision>
</link>
<gazebo>
<plugin name="${robot_namespace}_${suffix}_motor_model" filename="librotors_gazebo_motor_model.so">
<robotNamespace>${robot_namespace}</robotNamespace>
<jointName>${robot_namespace}/rotor_${motor_number}_joint</jointName>
<linkName>${robot_namespace}/rotor_${motor_number}</linkName>
<turningDirection>${direction}</turningDirection>
<timeConstantUp>${time_constant_up}</timeConstantUp>
<timeConstantDown>${time_constant_down}</timeConstantDown>
<maxRotVelocity>${max_rot_velocity}</maxRotVelocity>
<motorConstant>${motor_constant}</motorConstant>
<momentConstant>${moment_constant}</momentConstant>
<commandSubTopic>gazebo/command/motor_speed</commandSubTopic>
<motorNumber>${motor_number}</motorNumber>
<rotorDragCoefficient>${rotor_drag_coefficient}</rotorDragCoefficient>
<rollingMomentCoefficient>${rolling_moment_coefficient}</rollingMomentCoefficient>
<motorSpeedPubTopic>motor_speed/${motor_number}</motorSpeedPubTopic>
<rotorVelocitySlowdownSim>${rotor_velocity_slowdown_sim}</rotorVelocitySlowdownSim>
</plugin>
</gazebo>
<gazebo reference="${robot_namespace}/rotor_${motor_number}">
<material>Gazebo/${color}</material>
</gazebo>
</xacro:macro>
</robot>

Answer 1

I have faced a similar problem. The robot started to bounce when it was in contact with a surface. In my case, the source of problem was unrealistic inertia values of robot parts. Even if one of link has a bad calculated/estimated inertia, the model may bounce. I would propose you to verify calculations under inertial tags.