Executing the service command from c++ file

asked 2016-03-09 11:17:35 -0500

Anonymous

updated 2016-03-09 11:19:29 -0500

Here curr_x and curr_y are the co-ordinates of the turtle

I'm getting these errors when I try to execute the following command. I would like to teleport the turtle to absolute co-ordinates using the command

kv@kv:~/krssg$ rosservice call /turtle1/teleport_absolute "x: 0.25
y: 10.68
theta: -0.7854"

but I'm getting these errors when I to invoke this command from a c++ file

Traceback (most recent call last):
  File "/opt/ros/indigo/bin/rosservice", line 35, in <module>
    rosservice.rosservicemain()
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosservice/__init__.py", line 746, in rosservicemain
    _rosservice_cmd_call(argv)
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosservice/__init__.py", line 607, in _rosservice_cmd_call
    service_args.append(yaml.load(arg))
  File "/usr/lib/python2.7/dist-packages/yaml/__init__.py", line 71, in load
    return loader.get_single_data()
  File "/usr/lib/python2.7/dist-packages/yaml/constructor.py", line 37, in get_single_data
    node = self.get_single_node()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 127, in compose_mapping_node
    while not self.check_event(MappingEndEvent):
  File "/usr/lib/python2.7/dist-packages/yaml/parser.py", line 98, in check_event
    self.current_event = self.state()
  File "/usr/lib/python2.7/dist-packages/yaml/parser.py", line 428, in parse_block_mapping_key
    if self.check_token(KeyToken):
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 116, in check_token
    self.fetch_more_tokens()
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 220, in fetch_more_tokens
    return self.fetch_value()
  File "/usr/lib/python2.7/dist-packages/yaml/scanner.py", line 576, in fetch_value
    self.get_mark())
yaml.scanner.ScannerError: mapping values are not allowed here
  in "<string>", line 1, column 12:
    x: curr_x y: curr_y theta: 0.785
               ^
[ INFO] [1457543780.559175654]: 

[ INFO] [1457543780.559260990]: curr_x = 1.10889 curr_y = 9.98001
[ INFO] [1457543780.559285090]: [X][Y] = 0 0
Traceback (most recent call last):
  File "/opt/ros/indigo/bin/rosservice", line 35, in <module>
    rosservice.rosservicemain()
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosservice/__init__.py", line 746, in rosservicemain
    _rosservice_cmd_call(argv)
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rosservice/__init__.py", line 607, in _rosservice_cmd_call
    service_args.append(yaml.load(arg))
  File "/usr/lib/python2.7/dist-packages/yaml/__init__.py", line 71, in load
    return loader.get_single_data()
  File "/usr/lib/python2.7/dist-packages/yaml/constructor.py", line 37, in get_single_data
    node = self.get_single_node()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 36, in get_single_node
    document = self.compose_document()
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 55, in compose_document
    node = self.compose_node(None, None)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 84, in compose_node
    node = self.compose_mapping_node(anchor)
  File "/usr/lib/python2.7/dist-packages/yaml/composer.py", line 127, in compose_mapping_node
    while not self.check_event(MappingEndEvent):
  File ...

(more)

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answered 2016-03-10 01:47:44 -0500

Martin Peris
5625 ●34 ●83 ●98 http://www.linkedin.co...

updated 2016-03-10 01:49:29 -0500

According to this error message:

  yaml.scanner.ScannerError: mapping values are not allowed here
  in "<string>", line 1, column 12:
    x: curr_x y: curr_y theta: 0.785

and the invoke call that you posted as a comment on Tully's answer:

 system("rosservice call /turtle1/teleport_absolute {\"x: curr_x y: curr_y theta: 0.785\"}");

The problem is that you need to substitute the strings curr_x and curr_y in the system call for the actual x and y values (double) that you want to send.

I bet this system call works well:

 system("rosservice call /turtle1/teleport_absolute {\"x: 0.25, y: 10.68, theta: 0.785\"}");

Anyway, if you are working in C++ this is not the proper way to call a ROS service. Better take a look at this tutorial: Writing a Service Client Node

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answered 2016-03-09 15:56:32 -0500

tfoote

58457 ●128 ●550 ●526 http://www.ros.org/

The command line arguments need to be yaml. Copy and paste of yours worked for me. But to be more explicit use the one line yaml syntax more like "{x: 5.25, y: 10.68, theta: 1.085}"

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Comments

I tried the above method but I got this message

while parsing a flow mapping
  in "<string>", line 1, column 1:
    {x: curr_x y: curr_y theta: 0.785}

The invoke call was:

 system("rosservice call /turtle1/teleport_absolute {\"x: curr_x y: curr_y theta: 0.785\"}");

Anonymous ( 2016-03-10 01:13:38 -0500 )edit

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