ROS Basics in 5 Days Course Exercise 3.1 - WAM arm service error

[winckrc]

For Exercise 3.1, when I execute the file, I get the following output:

  ... logging to /home/user/.ros/log/804b3f80-cf9e-11eb-845e-0242c0a82008/roslaunch-1_xterm-18776.log
Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://1_xterm:32941/

SUMMARY
========

PARAMETERS
 * /rosdistro: noetic
 * /rosversion: 1.15.9

NODES
  /
iri_wam_reproduce_trajectory (iri_wam_reproduce_trajectory/iri_wam_reproduce_trajectory_node)
service_client (service_client_pkg/simple_service_client)
traj_by_name_node (trajectory_by_name/traj_by_name.py)

ROS_MASTER_URI=http://1_simulation:11311

process[iri_wam_reproduce_trajectory-1]: started with pid [18784]
process[traj_by_name_node-2]: started with pid [18785]
process[service_client-3]: started with pid [18786]
[ INFO] [1623961563.284887830]: Waiting for action server to start.
[ INFO] [1623961563.292194414]: Ready execute trajectories
[ INFO] [1623961563.298330172]: Running
[ERROR] [1623961563.299507396]: Failed to call service /trajectory_by_name
[service_client-3] process has died [pid 18786, exit code 1, cmd /home/user/catkin_ws/devel/lib/service_client_pkg/simple_service_client __name:=service_client __log:=/home/user/.ros/log/804b3f80-cf9e-11eb-845e-0242c0a82008/service_client-3.log].
log file: /home/user/.ros/log/804b3f80-cf9e-11eb-845e-0242c0a82008/service_client-3*.log

______________________________________________________________________
Here is my launch file:
<launch>
    <include file="$(find trajectory_by_name)/launch/start_service.launch"/>
  <node pkg ="service_client_pkg"
        type="simple_service_client"
        name="service_client"
        output="screen">
  </node>
</launch>

______________________________________________________________________
Here is my CMakeLists.txt file (the extra #'s are to keep the forum editor from weirdly formatting the text):
cmake_minimum_required(VERSION 3.0.2)
project(my_package)
## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)
## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  roscpp
)
## System dependencies are found with CMake's conventions

# find_package(Boost REQUIRED COMPONENTS system)

## Uncomment this if the package has a setup.py. This macro ensures

## modules and global scripts declared therein get installed

## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html

# catkin_python_setup()

################################################

## Declare ROS messages, services and actions ##

################################################

## To declare and build messages, services or actions from within this

## package, follow these steps:

## * Let MSG_DEP_SET be the set of packages whose message types you use in

##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).

## * In the file package.xml:

##   * add a build_depend tag for "message_generation"

##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET

##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in

##     but can be declared for certainty nonetheless:

##     * add a exec_depend tag for "message_runtime"

## * In this file (CMakeLists.txt):

##   * add "message_generation" and every package in MSG_DEP_SET to

##     find_package(catkin REQUIRED COMPONENTS ...)

##   * add "message_runtime" and every package in MSG_DEP_SET to

##     catkin_package(CATKIN_DEPENDS ...)

##   * uncomment the add_*_files sections below as needed

##     and list every .msg/.srv/.action file to be processed

##   * uncomment the generate_messages entry below

##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder

# add_message_files(

#   FILES

#   Message1.msg

#   Message2.msg

# )

## Generate services in the 'srv' folder

# add_service_files(

#   FILES

#   Service1.srv

#   Service2.srv

# )

## Generate actions in the 'action' folder

# add_action_files(

#   FILES

#   Action1.action

#   Action2.action

# )

## Generate added messages and services with any dependencies listed here

# generate_messages(

#   DEPENDENCIES

#   std_msgs  # Or other packages containing msgs

# )

################################################

## Declare ROS dynamic reconfigure parameters ##

################################################

## To declare and build dynamic reconfigure parameters within this

## package, follow these steps:

## * In the file package.xml:

##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"

## * In this file (CMakeLists.txt):

##   * add "dynamic_reconfigure" to

##     find_package(catkin REQUIRED COMPONENTS ...)

##   * uncomment the "generate_dynamic_reconfigure_options" section below

##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder

# generate_dynamic_reconfigure_options(

#   cfg/DynReconf1.cfg

#   cfg/DynReconf2.cfg

# )

###################################

## catkin specific configuration ##

###################################

## The catkin_package macro generates cmake config files for your package

## Declare things to be passed to dependent projects

## INCLUDE_DIRS: uncomment this if your package contains header files

## LIBRARIES: libraries you create in this project that dependent projects also need

## CATKIN_DEPENDS: catkin_packages dependent projects also need

## DEPENDS: system dependencies of this project that dependent projects also need

catkin_package(

#  INCLUDE_DIRS include

#  LIBRARIES my_package

#  CATKIN_DEPENDS roscpp

#  DEPENDS system_lib

)

###########

## Build ##

###########

## Specify additional locations of header files

## Your package locations should be listed before other locations

include_directories(

# include

  ${catkin_INCLUDE_DIRS}

)

## Declare a C++ library

# add_library(${PROJECT_NAME}

#   src/${PROJECT_NAME}/my_package.cpp

# )

## Add cmake target dependencies of the library

## as an example, code may need to be generated before libraries

## either from message generation or dynamic reconfigure

# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable

## With catkin_make all packages are built within a single CMake context

## The recommended prefix ensures that target names across packages don't collide

add_executable(simple src/simple.cpp)

## Rename C++ executable without prefix

## The above recommended prefix causes long target names, the following renames the

## target back to the shorter version for ease of user use

## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"

# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable

## same as for the library above

add_dependencies(simple ${simple_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against

target_link_libraries(simple

   ${catkin_LIBRARIES}

 )

#############

## Install ##

#############

# all install targets should use catkin DESTINATION variables

# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation

## in contrast to setup.py, you can choose the destination

# catkin_install_python(PROGRAMS

#   scripts/my_python_script

#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}

# )

## Mark executables for installation

## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html

# install(TARGETS ${PROJECT_NAME}_node

#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}

# )

## Mark libraries for installation

## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html

# install(TARGETS ${PROJECT_NAME}

#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}

#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}

#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}

# )

## Mark cpp header files for installation

# install(DIRECTORY include/${PROJECT_NAME}/

#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}

#   FILES_MATCHING PATTERN "*.h"

#   PATTERN ".svn" EXCLUDE

# )

## Mark other files for installation (e.g. launch and bag files, etc.)

# install(FILES

#   # myfile1

#   # myfile2

#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}

# )

#############

## Testing ##

#############

## Add gtest based cpp test target and link libraries

# catkin_add_gtest(${PROJECT_NAME}-test test/test_my_package.cpp)

# if(TARGET ${PROJECT_NAME}-test)

#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})

# endif()

## Add folders to be run by python nosetests

# catkin_add_nosetests(test)

[winckrc]

I think it has something to do with launching the service, because if I launch it manually, it works.

[roalgoal]

Hi, like the error says, it’s having an error when trying to launch the trajectory_by_name service, and your CMakeLists.txt doesn’t have the add_service_files( section commented out. This might be casing the problem. Also, maybe it’s the formatting of your launch file? I see that the include tag is in front of the node tag.

[winckrc]

The include tag before the node tag is the format used in the tutorial. The tutorial also does not say anything about editing the CMakeLists.txt file in relation to add_service_files(. I would think that an issue with CMakeLists.txt would cause the error even if I launch the service manually in the terminal, but if I do that, it works fine.

[roalgoal]

If it works with rosrun, then maybe your launch file is missing something. What’s inside start_service.launch? it looks like the node in charge of advertising the service /trajectory_by_name is maybe not getting launched?

[winckrc]

Thanks for the reply. At the bottom is my launch file. I’m wonder if there’s something wrong with the way I’m starting /trajectory_by_name. If I start the service using

roslaunch trajectory_by_name start_service.launch

in a different shell, then I launch traj_by_name.launch, then I get the same error message, but it works. Here’s the output that I get:

---

process[service_client-3]: started with pid [4968]
[ INFO] [1624372861.703965658]: Waiting for action server to start.
[ INFO] [1624372861.719344657]: Ready execute trajectories
[ERROR] [1624372862.339523019, 1351.325000000]: Failed to call service /trajectory_by_name
[ INFO] [1624372862.384915906, 1351.370000000]: Action server started, sending goal.
[service_client-3] process has died [pid 4968, exit code 1, cmd /home/user/catkin_ws/devel/lib/services_31/traj_by_name __name:=service_client __log:=/home/user/.ros/log/a809c7fc-d364-11eb-a106-0242c0a80008/service_client-3.log].
log file: /home/user/.ros/log/a809c7fc-d364-11eb-a106-0242c0a80008/service_client-3*.log
[ INFO] [1624372871.834794499, 1360.683000000]: Action finished: SUCCEEDED

---

If I don’t launch the service in a separate shell, then I get the error message, but it doesn’t run:

---

[ INFO] [1624372841.067351261]: Waiting for action server to start.
[ INFO] [1624372841.078982146]: Ready execute trajectories
[ERROR] [1624372841.092868362]: Failed to call service /trajectory_by_name
[service_client-3] process has died [pid 4877, exit code 1, cmd /home/user/catkin_ws/devel/lib/services_31/traj_by_name __name:=service_client __log:=/home/user/.ros/log/a809c7fc-d364-11eb-a106-0242c0a80008/service_client-3.log].
log file: /home/user/.ros/log/a809c7fc-d364-11eb-a106-0242c0a80008/service_client-3*.log

---

Here’s the launch file I’m using:

---

Launch File:
<launch>
    <include file="$(find trajectory_by_name)/launch/start_service.launch"/>
  <node pkg ="service_client_pkg"
        type="simple_service_client"
        name="service_client"
        output="screen">
  </node>
</launch>

[roalgoal]

Maybe you are launching more than one service servers, and that causes the nodes to kill each other. Try removing the start_service.launch from your launch file or killing everything else on your terminals

[winckrc]

If I start the service in a different shell, then it works. If I don’t - if I kill everything else - then it doesn’t work.

[bayodesegun]

Maybe you need to wait for the service in your code? Have a look at this post:

Exercise 3.1 Failed to call service

Hello! I can’t seem to complete Exercise 3.1, I checked my code and it is the same as the solution. Below is the error message: [48 PM] This is my launch file and CPP file: [32 PM] [39 PM] I believe we dont need to have the service running right? Because in my launch file of this exercise, the include file (find…) line is to start the service first so the /trajectory_by_name service is already running once I roslaunch my launch file, all we need is to call the service so the robot moves. …

[winckrc]

Thanks for the help! That fixed the problem. Since the c++ code is provided for this exercise, it seems like

ros::service::waitForService("/trajectory_by_name");

should be included in the provided code.