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M1chaelM edited this page Mar 26, 2022 · 2 revisions

Overview

The purpose of this tutorial is to demonstrate how to create a custom WAM-V thruster and component configuration for competition. Allowable configurations are documented in the VRX Technical Guide, available on the VRX competition website. This involves writing a user-generated thruster YAML file and a user-generated component YAML file, and then running a script that will generate a custom WAM-V URDF file with the specified thrusters and components. This WAM-V URDF file can then be passed in as a parameter to the VRX simulation roslaunch files.

In addition, this script also makes sure that the requested thruster and component configurations are in compliance with basic VRX constraints. More details about compliance below.

Quick Start Instructions:

Example 1: How to use generate_wamv.launch

  • First be sure your VRX workspace is built and sourced. Then launch the example world:

    roslaunch vrx_gazebo sydneyregatta.launch

  • Look at the WAM-V in the Sydney Regatta Centre. It currently has the default thruster configuration and component configuration for sydneyregatta.launch (as of July 15, 2021, the default configuration is the H thruster configuration and no components). In Gazebo, click View => Transparent to see the thrusters.

    Default_Sensors_And_Thrusters.jpg

  • Close gazebo

  • Make a directory for your custom WAM-V, eg:

    mkdir ~/my_wamv

  • Scroll down this tutorial and copy the contents of Example Compliant Yaml Thruster Configuration File 1. Next, paste those contents into a new file.

    gedit ~/my_wamv/thruster_config.yaml

    Later, we will edit this file to customize your WAM-V.

  • Scroll down this tutorial and copy the contents of Example Compliant Yaml Component Configuration File 1. Next, paste those contents into a new file.

    gedit ~/my_wamv/component_config.yaml

    Later, we will edit this file to customize your WAM-V.

  • Run the script to generate your WAM-V's URDF with these newly specified thrusters and components. Note: on most systems, $HOME is /home/<username>. If this is not the case, you can change all uses of $HOME to /home/<username>.

    roslaunch vrx_gazebo generate_wamv.launch thruster_yaml:=$HOME/my_wamv/thruster_config.yaml  component_yaml:=$HOME/my_wamv/component_config.yaml wamv_target:=$HOME/my_wamv/my_wamv.urdf

    Parameters Explained:

    • thruster_yaml: input, the full path of the thruster YAML configuration file. If not given, uses the default thruster yaml

    • component_yaml: input, the full path of the component YAML configuration file. If not given, uses the default component yaml

    • wamv_target: output, the full path to the WAM-V URDF, which will be generated

  • See the following confirmation message in the terminal with no errors present

[INFO] [1566845959.198003]:
Using /home/tylerlum/my_wamv/thruster_config.yaml as the thruster configuration yaml file

[INFO] [1566845959.208003]: 
Using /home/tylerlum/my_wamv/component_config.yaml as the component configuration yaml file

xacro: in-order processing became default in ROS Melodic. You can drop the option.

WAM-V urdf file sucessfully generated. File location: /home/tylerlum/my_wamv/my_wamv.urdf
================================================================================REQUIRED process [wamv_config/wamv_generator-2] has died!
process has finished cleanly
log file: /home/tylerlum/.ros/log/9b1fd6a0-c833-11e9-a434-dcfb48e97aeb/wamv_config-wamv_generator-2*.log
Initiating shutdown!
================================================================================

  • Launch the example world with your WAM-V:

    roslaunch vrx_gazebo sydneyregatta.launch urdf:=$HOME/my_wamv/my_wamv.urdf

  • Look at the WAM-V in the Sydney Regatta Centre. It should have your thruster and component configurations. If everything went correctly and you used the example thruster and component configuration yaml files below, you should see the desired components and you can click View => Transparent to see the desired thrusters.

    Desired_Thruster_Config.jpg

    Desired_Components.png

  • Confirm that these are the thrusters and components you want in the places that you want

  • Observe the ros topics being published and confirm they are the topics you want:

    rostopic list

  • Close gazebo

Example 2: How to Further Customize Your WAM-V

Next, let's customize the WAM-V further.

  • Scroll down this tutorial and copy the contents of Example Compliant Yaml Thruster Configuration File 2. Next, paste those contents into the thruster_config.yaml file, replacing all previous text. Note the addition of the third thruster.

       $ gedit ~/my_wamv/thruster_config.yaml

  • Scroll down this tutorial and copy the contents of Example Compliant Yaml Component Configuration File 2. Next, paste those contents into the component_config.yaml file, replacing all previous text. Note the removal of the cameras.

       $ gedit ~/my_wamv/component_config.yaml

  • Next, we need to run generate_wamv.launch again to use these new yamls files to create a new urdf file.

       $ roslaunch vrx_gazebo generate_wamv.launch thruster_yaml:=$HOME/my_wamv/thruster_config.yaml  component_yaml:=$HOME/my_wamv/component_config.yaml wamv_target:=$HOME/my_wamv/my_wamv_2.urdf

  • See the following confirmation message in the terminal with no errors present

[INFO] [1566846607.783282]: 
Using /home/tylerlum/my_wamv/thruster_config.yaml as the thruster configuration yaml file

[INFO] [1566846607.792693]: 
Using /home/tylerlum/my_wamv/component_config.yaml as the component configuration yaml file

xacro: in-order processing became default in ROS Melodic. You can drop the option.

WAM-V urdf file sucessfully generated. File location: /home/tylerlum/my_wamv/my_wamv_2.urdf
================================================================================REQUIRED process [wamv_config/wamv_generator-2] has died!
process has finished cleanly
log file: /home/tylerlum/.ros/log/1db4cc0a-c835-11e9-a434-dcfb48e97aeb/wamv_config-wamv_generator-2*.log
Initiating shutdown!
================================================================================

  • Launch the example world with your WAM-V:

       $ roslaunch vrx_gazebo sydneyregatta.launch urdf:=$HOME/my_wamv/my_wamv_2.urdf

  • Look at the WAM-V in the Sydney Regatta Centre. It should have your new thruster and component configurations. If everything went correctly and you used the example thruster and component configuration yaml files below, you should see the desired components and you can click View => Transparent to see the desired thrusters. Please note the missing cameras and additional thruster.

Desired_Configuration_2.jpg

Example 3: Non-compliance

Next, let's see how compliance works.

  • Scroll down this tutorial and copy the contents of Example Non-compliant Yaml Thruster Configuration File. Next, paste those contents into the thruster_config.yaml file, replacing all previous text. Note the addition of the third thruster in a non-compliant position.

       $ gedit ~/my_wamv/thruster_config.yaml

  • Scroll down this tutorial and copy the contents of Example Non-compliant Yaml Component Configuration File. Next, paste those contents into the component_config.yaml file, replacing all previous text. Note the addition of 5 cameras.

       $ gedit ~/my_wamv/component_config.yaml

  • Next, we need to run generate_wamv.launch again to use these new yamls files to create a new urdf file.

       $ roslaunch vrx_gazebo generate_wamv.launch thruster_yaml:=$HOME/my_wamv/thruster_config.yaml  component_yaml:=$HOME/my_wamv/component_config.yaml wamv_target:=$HOME/my_wamv/my_wamv_3.urdf

  • See the following messages in the terminal

Using /home/tylerlum/my_wamv/thruster_config.yaml as the thruster configuration yaml file

[ERROR] [1566846830.001315]: engine second_right is out of bounds
[ERROR] [1566846830.001882]: engine second_right is at xyz=(-2.373776, -1.027135, 0.318237), it must fit in at least one of the following boxes with remaining space:
[ERROR] [1566846830.002445]:   <Box name:thruster_compliance_port_aft x:[-1.75, -2.75] y:[1.5,0.5] z:[0.6,-0.6]                remaining_space:0>
[ERROR] [1566846830.002985]:   <Box name:thruster_compliance_star_for x:[1.5, 0.5] y:[-0.5,-1.5] z:[0.6,-0.6]                remaining_space:1>
[ERROR] [1566846830.003573]:   <Box name:thruster_compliance_port_for x:[1.5, 0.5] y:[1.5,0.5] z:[0.6,-0.6]                remaining_space:1>
[ERROR] [1566846830.004085]:   <Box name:thruster_compliance_star_aft x:[-1.75, -2.75] y:[-0.5,-1.5] z:[0.6,-0.6]                remaining_space:0>
[ERROR] [1566846830.004618]:   <Box name:thruster_compliance_middle x:[1.5, -1.0] y:[0.5,-0.5] z:[0.6,-0.6]                remaining_space:1>
[INFO] [1566846830.006693]: 
Using /home/tylerlum/my_wamv/component_config.yaml as the component configuration yaml file

[ERROR] [1566846830.013150]: Too many wamv_camera requested
[ERROR] [1566846830.013670]:   maximum of 3 wamv_camera allowed
xacro: in-order processing became default in ROS Melodic. You can drop the option.

[ERROR] [1566846830.477420]: 
This component/thruster configuration is NOT compliant with the (current) VRX constraints. A urdf file will be created, but please note that the above errors must be fixed for this to be a valid configuration for the VRX competition.

WAM-V urdf file sucessfully generated. File location: /home/tylerlum/my_wamv/my_wamv_3.urdf
================================================================================REQUIRED process [wamv_config/wamv_generator-2] has died!
process has finished cleanly
log file: /home/tylerlum/.ros/log/a223962e-c835-11e9-a434-dcfb48e97aeb/wamv_config-wamv_generator-2*.log
Initiating shutdown!
================================================================================

The URDF file is still created, but these error messages show why your configuration is not compliant. There are too many cameras and two thrusters that are too close together (more details about this in the Compliance section).

Next, launch the example world with your WAM-V:

$ roslaunch vrx_gazebo sydneyregatta.launch urdf:=$HOME/my_wamv/my_wamv_3.urdf

Look at the WAM-V in the Sydney Regatta Centre. It should have your new thruster and component configurations. If everything went correctly and you used the example thruster and component configuration yaml files below, you should see the desired components and thrusters. Please note the multiple cameras.

Five Cameras.png

Compliance

As of July 15, 2021 there are 3 main compliance rules

  • All components must be contained within one of the component bounding boxes (details here). The image below shows the position of the bounding boxes as of July 15, 2021.

Sensor_Bounding_Boxes.png

  • All thrusters must be contained within one of the thruster bounding boxes (details here). The image below shows the position of the bounding boxes as of July 15, 2021.

Thruster_Bounding_Boxes.png

  • The number of each component and thruster in the configuration must be within the limit defined here for components and here for thrusters.

  • For thrusters, there can only be one thruster in each bounding box. This is to prevent teams from stacking thrusters together in one location, which is physically infeasible.

Please note that if you call generate_wamv.launch on non-compliant configuration YAML files, red error messages will be printed but the URDF file will still be created and be able to be used as usual. However, it is not a valid configuration for the VRX competition.

Please note that the compliance tests from compliance.py is a first test. It is not extensive and may be updated. If your configuration does not pass the test, it is probably not a valid configuration for the VRX competition. If your configuration does pass the test, it is probably a valid configuration for the VRX competition, but please keep your designs to physically feasible solutions. See the VRX Technical Guide for specifics on the constraints for the VRX competition, available at the Documentation Wiki.

If you have any issues or concerns with how compliance works, please create an issue here and we will help to resolve the issue.

Details of Implementation

generate_wamv.launch is a simple script that takes in thruster and component configurations YAML files as inputs and outputs a urdf file to be used in simulation. It also checks to see if the thrusters and components are in compliance as defined by compliance.py.

It operates by generating macro calls specified by the user-generated YAML configuration files. It currently checks for compliance by ensuring that all components and thrusters are in a valid bounding box region and that there are a valid number of each item.

If the thruster/component configuration passes, the script creates two xacro files. One is a thruster xacro file in the same directory as the thruster yaml file with the same file name, but with a .xacro extension. The second is a component xacro file in the same directory as the component yaml file with the same file name, but with a .xacro extension.

Next, it calls a xacro command to generate the urdf at wamv_target using this file.

Important Cases

  • To setup a WAM-V with no thruster and no components, you can create empty files empty_thruster_config.yaml and empty_component_config.yaml and then pass them in as parameters to generate_wamv.launch

  • When sydneyregatta.launch or any other simulation launch file is called, if the urdf parameter is given, it will use that file for the WAM-V configuration. If the urdf parameter is not given, then it will use the default configuration given in the launch file.

Supported Thrusters and Components

Supported thrusters and components can be seen in allowed thrusters and allowed components (currently as of July 15, 2021 we have only one thruster type).

Thrusters and Components Default and Required Parameters

All components and thrusters have numerous parameters. As of August 2021, these include name, prefix, position, orientation, x, y, z, R, P, Y, post_Y, depending on the component or thruster. You can view the parameters for components here and the parameters for thrusters here.

As of Aug 2019, you can click on wamv_camera.xacro and you will see:

<xacro:macro name="wamv_camera" params="name x:=0.5 y:=0 z:=1.5 R:=0 P:=0 Y:=0 post_Y:=0">

This means that name is a required parameter, and the others all have defaults.

As of Aug 2021, you can click on engine.xacro and you will see:

<xacro:macro name="engine" params="prefix position:='0 0 0' orientation:='0 0 0'">

This means that prefix is a required parameter, and that position and orientation have defaults.

position, orientation, and xyzRPY define the exact pose of the component/thruster you want with respect to the WAM-V. post_Y is only for components and simply changes the angle at which the post is sitting underneath the given component.

Examples

Example Compliant Yaml Thruster Configuration File 1

engine:
  - prefix: "left"
    position: "-2.373776 1.027135 0.318237"
    orientation: "0.0 0.0 0.0"
  - prefix: "right"
    position: "-2.373776 -1.027135 0.318237"
    orientation: "0.0 0.0 0.0"

Example Compliant Yaml Thruster Configuration File 2

engine:
  - prefix: "left"
    position: "-2.373776 1.027135 0.318237"
    orientation: "0.0 0.0 0.0"
  - prefix: "right"
    position: "-2.373776 -1.027135 0.318237"
    orientation: "0.0 0.0 0.0"

  # Adding new thruster
  - prefix: "middle"
    position: "0 0 0.318237"
    orientation: "0.0 0.0 0.0"

Example Non-compliant Yaml Thruster Configuration File

engine:
  - prefix: "left"
    position: "-2.373776 1.027135 0.318237"
    orientation: "0.0 0.0 0.0"
  - prefix: "right"
    position: "-2.373776 -1.027135 0.318237"
    orientation: "0.0 0.0 0.0"

  # Adding new thruster in non-compliant position
  - prefix: "second_right"
    position: "-2.373776 -1.027135 0.318237"
    orientation: "0.0 0.0 0.0"

Example Compliant Yaml Component Configuration File 1

wamv_camera:
    - name: front_left_camera
      x: 0.75
      y: 0.1
      P: ${radians(15)}
    - name: front_right_camera
      x: 0.75
      y: -0.1
      P: ${radians(15)}
    - name: middle_right_camera
      x: 0.75
      y: 0.3
      P: ${radians(15)}
wamv_gps:
    - name: gps_wamv
      x: -0.85
wamv_imu:
    - name: imu_wamv
      y: -0.2
lidar:
    - name: lidar_wamv
      type: 16_beam
      P: ${radians(8)}
wamv_ball_shooter:
    - name: ball_shooter
      x: 0.55
      y: -0.3
      z: 1.3
      pitch: ${radians(-20)}
      yaw: 0

Example Compliant Yaml Component Configuration File 2

# Removed all cameras

wamv_gps:
    - name: gps_wamv
      x: -0.85
wamv_imu:
    - name: imu_wamv
      y: -0.2
lidar:
    - name: lidar_wamv
      type: 16_beam
      P: ${radians(8)}
wamv_ball_shooter:
    - name: ball_shooter
      x: 0.55
      y: -0.3
      z: 1.3
      pitch: ${radians(-20)}
      yaw: 0

Example Non-compliant Yaml Component Configuration File

# Too many cameras
wamv_camera:
    - name: front_left_camera
      x: 0.75
      y: 0.1
      P: ${radians(15)}
    - name: front_right_camera
      x: 0.75
      y: -0.1
      P: ${radians(15)}
    - name: front_far_left_camera
      x: 0.75
      y: 0.3
      P: ${radians(15)}
    - name: front_far_right_camera
      x: 0.75
      y: -0.3
      P: ${radians(15)}
    - name: middle_left_camera
      x: 0.6
      y: 0.4
      P: ${radians(15)}
      Y: ${radians(90)}
      post_Y: ${radians(90)}

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