Segmentation Fault when trying to run mocap_hl_commander.py using OptiTrack #1615

Amin-Yazdanshenas · 2024-10-29T18:51:42Z

Amin-Yazdanshenas
Oct 29, 2024

Hi everyone,

I'm facing a segmentation fault when I try to run mocap_hl_commander.py using the OptiTrack system with my Crazyflie with the Motion capture marker deck. Here are the details:
The optitrack streaming info on Motive: tracker 3.1.0 Beta 1 are as follow:

I’m connected to the same WiFi network as the OptiTrack system, and I've verified connectivity by pinging the IP address successfully.
ping 192.168.0.118 PING 192.168.0.118 (192.168.0.118) 56(84) bytes of data. 64 bytes from 192.168.0.118: icmp_seq=1 ttl=128 time=3.59 ms ...

Here are the changes that I made to mocap_hl_commander.py to match my setup:

uri = uri_helper.uri_from_env(default='radio://0/80/2M/E7E7E7E702')
host_name = '192.168.0.118'
mocap_system_type = 'optitrack'
rigid_body_name = 'cf'

Issue: When running my script, I encounter a segmentation fault (core dumped)
).

Answered by Amin-Yazdanshenas

Nov 1, 2024

I fixed the issue; you can find the solution here. I hope they get it fixed in their code.

View full answer

knmcguire · 2024-10-30T09:06:50Z

knmcguire
Oct 30, 2024

Hi! Seems you are missing the error message, could you copy paste the whole message in the terminal?

8 replies

Amin-Yazdanshenas Oct 30, 2024
Author

I have dug deeper into the issue, and I've noticed the issue is with mc.waitForNextFrame(). Also, below, I have put the modification that I made to the code to accommodate the debug process better.

code:

class MocapWrapper(Thread):
    def __init__(self, body_name):
        Thread.__init__(self)

        self.body_name = body_name
        self.on_pose = None
        self._stay_open = True

        self.start()

    def close(self):
        self._stay_open = False

    def run(self):
        print("Attempting to connect to motion capture system...")
        try:
            mc = motioncapture.connect(mocap_system_type, {'hostname': host_name})
            print("Connected successfully.")
        except Exception as e:
            print(f"Failed to connect: {e}")
            return  # Exit the run method if connection fails
        
        while self._stay_open:
            try:
                print("Waiting for next frame...")
                mc.waitForNextFrame()
                print("Frame received.")
            except Exception as e:
                print(f"Error during frame acquisition: {e}")
            for name, obj in mc.rigidBodies.items():
                if name == self.body_name:
                    if self.on_pose:
                        pos = obj.position
                        self.on_pose([pos[0], pos[1], pos[2], obj.rotation])

error:

Attempting to connect to motion capture system...
Connected successfully.
Waiting for next frame...
Segmentation fault (core dumped)

more detailed error using gdb:

gdb --args python mocap_hl_commander.py 
GNU gdb (Ubuntu 12.1-0ubuntu1~22.04.2) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from python...
Reading symbols from /usr/lib/debug/.build-id/d6/44f64e3b3b3ad160cd4c46ce8cdf08dab8daef.debug...
(gdb) run
Starting program: /usr/bin/python mocap_hl_commander.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff1400640 (LWP 100382)]
[New Thread 0x7ffff0a00640 (LWP 100383)]
[New Thread 0x7fffee000640 (LWP 100384)]
[New Thread 0x7fffeb600640 (LWP 100385)]
[New Thread 0x7fffe8c00640 (LWP 100386)]
[New Thread 0x7fffe4200640 (LWP 100387)]
[New Thread 0x7fffe1800640 (LWP 100388)]
[New Thread 0x7fffdee00640 (LWP 100389)]
[New Thread 0x7fffde400640 (LWP 100390)]
[New Thread 0x7fffd9a00640 (LWP 100391)]
[New Thread 0x7fffd7000640 (LWP 100392)]
[New Thread 0x7fffd4600640 (LWP 100393)]
[New Thread 0x7fffd1c00640 (LWP 100394)]
[New Thread 0x7fffcf200640 (LWP 100395)]
[New Thread 0x7fffcc800640 (LWP 100396)]
[New Thread 0x7fffc9800640 (LWP 100397)]
Attempting to connect to motion capture system...
Connected successfully.
Waiting for next frame...
[New Thread 0x7fffc8e00640 (LWP 100398)]
[New Thread 0x7fffc3e00640 (LWP 100399)]

Thread 17 "python" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffc9800640 (LWP 100397)]
__strlen_evex () at ../sysdeps/x86_64/multiarch/strlen-evex.S:77
77	../sysdeps/x86_64/multiarch/strlen-evex.S: No such file or directory.
(gdb) backtrace
#0  __strlen_evex () at ../sysdeps/x86_64/multiarch/strlen-evex.S:77
#1  0x00007ffff70b0674 in libmotioncapture::MotionCaptureOptitrack::waitForNextFrame() ()
   from /home/aminys/.local/lib/python3.10/site-packages/motioncapture.cpython-310-x86_64-linux-gnu.so
#2  0x00007ffff70a0ab8 in ?? () from /home/aminys/.local/lib/python3.10/site-packages/motioncapture.cpython-310-x86_64-linux-gnu.so
#3  0x00007ffff709bb6a in ?? () from /home/aminys/.local/lib/python3.10/site-packages/motioncapture.cpython-310-x86_64-linux-gnu.so
#4  0x00005555556b0b2e in cfunction_call (func=<built-in method waitForNextFrame of PyCapsule object at remote 0x7ffff749a3a0>, args=<optimized out>, kwargs=<optimized out>)
    at ../Objects/methodobject.c:543
#5  0x00005555556a72db in _PyObject_MakeTpCall (tstate=0x555555e0b690, callable=<built-in method waitForNextFrame of PyCapsule object at remote 0x7ffff749a3a0>, 
    args=<optimized out>, nargs=<optimized out>, keywords=0x0) at ../Objects/call.c:215
#6  0x00005555556bf55b in _PyObject_VectorcallTstate (kwnames=<optimized out>, nargsf=<optimized out>, args=0x7ffff74d29d8, 
    callable=<built-in method waitForNextFrame of PyCapsule object at remote 0x7ffff749a3a0>, tstate=0x555555e0b690) at ../Include/cpython/abstract.h:112
#7  _PyObject_VectorcallTstate (kwnames=<optimized out>, nargsf=<optimized out>, args=0x7ffff74d29d8, 
    callable=<built-in method waitForNextFrame of PyCapsule object at remote 0x7ffff749a3a0>, tstate=0x555555e0b690) at ../Include/cpython/abstract.h:99
#8  method_vectorcall (method=<optimized out>, args=0x7ffff74d29e0, nargsf=<optimized out>, kwnames=<optimized out>) at ../Objects/classobject.c:53
#9  0x000055555569f34a in _PyObject_VectorcallTstate (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff74d29e0, callable=<method at remote 0x7ffff603b140>, 
    tstate=0x555555e0b690) at ../Include/cpython/abstract.h:114
#10 PyObject_Vectorcall (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff74d29e0, callable=<method at remote 0x7ffff603b140>) at ../Include/cpython/abstract.h:123
#11 call_function (kwnames=0x0, oparg=<optimized out>, pp_stack=<synthetic pointer>, trace_info=0x7fffc97ff940, tstate=<optimized out>) at ../Python/ceval.c:5893
#12 _PyEval_EvalFrameDefault (tstate=<optimized out>, f=<optimized out>, throwflag=<optimized out>) at ../Python/ceval.c:4181
#13 0x00005555556b142c in _PyEval_EvalFrame (throwflag=0, 
    f=Frame 0x7ffff74d2840, for file /home/aminys/docker_shr/crazyflie_ws/crazyflie-lib-python/examples/mocap/mocap_hl_commander.py, line 109, in run (self=<MocapWrapper(_target=None, _name='Thread-1', _args=(), _kwargs={}, _daemonic=False, _ident=140736573998656, _native_id=100397, _tstate_lock=<_thread.lock at remote 0x7ffff603ae00>, _started=<Event(_cond=<Condition(_lock=<_thread.lock at remote 0x7ffff6323700>, acquire=<built-in method acquire of _thread.lock object at remote 0x7ffff6323700>, release=<built-in met--Type <RET> for more, q to quit, c to continue without paging--c
hod release of _thread.lock object at remote 0x7ffff6323700>, _waiters=<collections.deque at remote 0x7ffff63f2e00>) at remote 0x7ffff74ab730>, _flag=True) at remote 0x7ffff74ab760>, _is_stopped=False, _initialized=True, _stderr=<_io.TextIOWrapper at remote 0x7ffff7571220>, _invoke_excepthook=<function at remote 0x7ffff60471c0>, body_name='cf', on_pose=None, _stay_open=True) at remote 0x7ffff74ab790>, mc=<motioncapture.MotionCaptureOptitrack at remote 0x7ffff603b2f0>), tstate=0x555555e0b690) at ../Include/internal/pycore_ceval.h:46
#14 _PyEval_Vector (kwnames=<optimized out>, argcount=<optimized out>, args=<optimized out>, locals=0x0, con=0x7ffff6046d50, tstate=0x555555e0b690) at ../Python/ceval.c:5067
#15 _PyFunction_Vectorcall (func=<function at remote 0x7ffff6046d40>, stack=<optimized out>, nargsf=<optimized out>, kwnames=<optimized out>) at ../Objects/call.c:342
#16 0x0000555555699abb in _PyObject_VectorcallTstate (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff75be490, callable=<function at remote 0x7ffff6046d40>, tstate=0x555555e0b690) at ../Include/cpython/abstract.h:114
#17 PyObject_Vectorcall (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff75be490, callable=<function at remote 0x7ffff6046d40>) at ../Include/cpython/abstract.h:123
#18 call_function (kwnames=0x0, oparg=<optimized out>, pp_stack=<synthetic pointer>, trace_info=0x7fffc97ffb20, tstate=<optimized out>) at ../Python/ceval.c:5893
#19 _PyEval_EvalFrameDefault (tstate=<optimized out>, f=<optimized out>, throwflag=<optimized out>) at ../Python/ceval.c:4198
#20 0x00005555556b142c in _PyEval_EvalFrame (throwflag=0, f=Frame 0x7ffff75be320, for file /usr/lib/python3.10/threading.py, line 1016, in _bootstrap_inner (self=<MocapWrapper(_target=None, _name='Thread-1', _args=(), _kwargs={}, _daemonic=False, _ident=140736573998656, _native_id=100397, _tstate_lock=<_thread.lock at remote 0x7ffff603ae00>, _started=<Event(_cond=<Condition(_lock=<_thread.lock at remote 0x7ffff6323700>, acquire=<built-in method acquire of _thread.lock object at remote 0x7ffff6323700>, release=<built-in method release of _thread.lock object at remote 0x7ffff6323700>, _waiters=<collections.deque at remote 0x7ffff63f2e00>) at remote 0x7ffff74ab730>, _flag=True) at remote 0x7ffff74ab760>, _is_stopped=False, _initialized=True, _stderr=<_io.TextIOWrapper at remote 0x7ffff7571220>, _invoke_excepthook=<function at remote 0x7ffff60471c0>, body_name='cf', on_pose=None, _stay_open=True) at remote 0x7ffff74ab790>), tstate=0x555555e0b690) at ../Include/internal/pycore_ceval.h:46
#21 _PyEval_Vector (kwnames=<optimized out>, argcount=<optimized out>, args=<optimized out>, locals=0x0, con=0x7ffff7328200, tstate=0x555555e0b690) at ../Python/ceval.c:5067
#22 _PyFunction_Vectorcall (func=<function at remote 0x7ffff73281f0>, stack=<optimized out>, nargsf=<optimized out>, kwnames=<optimized out>) at ../Objects/call.c:342
#23 0x0000555555699abb in _PyObject_VectorcallTstate (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff7546d90, callable=<function at remote 0x7ffff73281f0>, tstate=0x555555e0b690) at ../Include/cpython/abstract.h:114
#24 PyObject_Vectorcall (kwnames=0x0, nargsf=<optimized out>, args=0x7ffff7546d90, callable=<function at remote 0x7ffff73281f0>) at ../Include/cpython/abstract.h:123
#25 call_function (kwnames=0x0, oparg=<optimized out>, pp_stack=<synthetic pointer>, trace_info=0x7fffc97ffd00, tstate=<optimized out>) at ../Python/ceval.c:5893
#26 _PyEval_EvalFrameDefault (tstate=<optimized out>, f=<optimized out>, throwflag=<optimized out>) at ../Python/ceval.c:4198
#27 0x00005555556bf4e1 in _PyEval_EvalFrame (throwflag=0, f=Frame 0x7ffff7546c20, for file /usr/lib/python3.10/threading.py, line 973, in _bootstrap (self=<MocapWrapper(_target=None, _name='Thread-1', _args=(), _kwargs={}, _daemonic=False, _ident=140736573998656, _native_id=100397, _tstate_lock=<_thread.lock at remote 0x7ffff603ae00>, _started=<Event(_cond=<Condition(_lock=<_thread.lock at remote 0x7ffff6323700>, acquire=<built-in method acquire of _thread.lock object at remote 0x7ffff6323700>, release=<built-in method release of _thread.lock object at remote 0x7ffff6323700>, _waiters=<collections.deque at remote 0x7ffff63f2e00>) at remote 0x7ffff74ab730>, _flag=True) at remote 0x7ffff74ab760>, _is_stopped=False, _initialized=True, _stderr=<_io.TextIOWrapper at remote 0x7ffff7571220>, _invoke_excepthook=<function at remote 0x7ffff60471c0>, body_name='cf', on_pose=None, _stay_open=True) at remote 0x7ffff74ab790>), tstate=0x555555e0b690) at ../Include/internal/pycore_ceval.h:46
#28 _PyEval_Vector (kwnames=0x0, argcount=1, args=0x7fffc97ffda8, locals=0x0, con=0x7ffff7327f50, tstate=0x555555e0b690) at ../Python/ceval.c:5067
#29 _PyFunction_Vectorcall (kwnames=0x0, nargsf=1, stack=0x7fffc97ffda8, func=<function at remote 0x7ffff7327f40>) at ../Objects/call.c:342
#30 _PyObject_VectorcallTstate (kwnames=0x0, nargsf=1, args=0x7fffc97ffda8, callable=<function at remote 0x7ffff7327f40>, tstate=0x555555e0b690) at ../Include/cpython/abstract.h:114
#31 method_vectorcall (method=<optimized out>, args=0x7ffff7504088, nargsf=<optimized out>, kwnames=<optimized out>) at ../Objects/classobject.c:61
#32 0x00005555557e83aa in thread_run (boot_raw=0x7ffff63eb990) at ../Modules/_threadmodule.c:1100
#33 0x00005555557dcfe8 in pythread_wrapper (arg=<optimized out>) at ../Python/thread_pthread.h:253
#34 0x00007ffff7c94ac3 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#35 0x00007ffff7d26850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Amin-Yazdanshenas Oct 30, 2024
Author

I made some progress. I followed the instructions on the link here https://github.com/IMRCLab/libmotioncapture. The cpp example worked perfectly fine and I managed to get the following outputs

$./motioncapture_example optitrack 192.168.0.28

frame 1
  timestamp: 1306569605211 us
  latency: 
    Camera 0.0030798 s
    Motive 0.0004408 s
  pointcloud:
    "0": [5.00533,0.671825,1.15226]
    "1": [5.0049,0.648757,0.957348]
    "2": [0.00821403,-0.0605278,0.00128402]
    "3": [-0.0046349,-0.0306264,0.0296097]
    "4": [0.0111815,0.00957737,0.0287507]
    "5": [0.0373421,0.0263541,0.000659066]
    "6": [0.0399092,-0.00896594,0.0318063]
    "7": [-0.017949,-0.00150189,-0.00114769]
    "8": [0.0667806,-0.0311503,0.00163713]
    "9": [0.0334528,-0.040019,0.0305964]
    "10": [5.00533,0.671825,1.15226]
    "11": [5.0049,0.648757,0.957348]
  rigid bodies:
    "cf":
       position: [0.021808, -0.0170989, 0.015376]
       rotation: [0.973978, 0.0121774, 0.0176845, 0.225622]
frame 2
  timestamp: 1306569613544 us
  latency: 
    Camera 0.0030713 s
    Motive 0.000563 s
  pointcloud:
    "0": [5.00559,0.671883,1.15225]
    "1": [5.00521,0.648827,0.957261]
    "2": [0.00812422,-0.0601368,0.00146676]
    "3": [-0.004634,-0.0306304,0.0296455]
    "4": [0.0111742,0.0095579,0.0287633]
    "5": [0.037337,0.0263602,0.000668719]
    "6": [0.0399073,-0.00897066,0.0318293]
    "7": [-0.0181451,-0.00133082,-0.000896537]
    "8": [0.0667778,-0.0311383,0.00166045]
    "9": [0.0334474,-0.0400149,0.03061]
    "10": [5.00559,0.671883,1.15225]
    "11": [5.00521,0.648827,0.957261]
  rigid bodies:
    "cf":
       position: [0.0217603, -0.0170162, 0.015458]
       rotation: [0.974052, 0.0129687, 0.0186009, 0.225187]

but when I tried the Python version, I faced the segmentation fault again

$python3 examples/python.py optitrack 192.168.0.28
Segmentation fault (core dumped)

which now I am 100 percent sure, the problem is with " mc.waitForNextFrame()"

knmcguire Oct 31, 2024

Thank for the thorough investigation! Debugging a C++ based library with a python wrapper is tough to do.

So there are two issues here:

We don't handle these issues in a good way in our scripts, we can fix that with try: except
The error is in the external motion capture library, which is unfortunately more out of our control.

Would you mind to make an issue in https://github.com/IMRCLab/libmotioncapture such that the maintainers know? You can link to this discussion.

Amin-Yazdanshenas Oct 31, 2024
Author

Thank you for your feedback and for clarifying the two main issues!
I’ll open an issue on the IMRCLab/libmotioncapture GitHub page to bring this to their attention and link to our discussion here for context.

knmcguire Nov 1, 2024

Thanks! Share the issue here so we can keep a check on it and see what the right approach is to make things run smoother from our end

Amin-Yazdanshenas · 2024-11-01T20:41:46Z

Amin-Yazdanshenas
Nov 1, 2024
Author

I fixed the issue; you can find the solution here. I hope they get it fixed in their code.

0 replies

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Bitcraze

Segmentation Fault when trying to run mocap_hl_commander.py using OptiTrack #1615

{{title}}

{{editor}}'s edit

{{editor}}'s edit

Replies: 2 comments 8 replies

{{title}}

{{title}}

{{title}}

{{title}}

{{title}}

{{title}}

{{title}}

{{editor}}'s edit

{{editor}}'s edit

Select a reply

Bitcraze

Segmentation Fault when trying to run mocap_hl_commander.py using OptiTrack #1615

Amin-Yazdanshenas Oct 29, 2024

Replies: 2 comments · 8 replies

knmcguire Oct 30, 2024

Amin-Yazdanshenas Oct 30, 2024 Author

Amin-Yazdanshenas Oct 30, 2024 Author

knmcguire Oct 31, 2024

Amin-Yazdanshenas Oct 31, 2024 Author

knmcguire Nov 1, 2024

Amin-Yazdanshenas Nov 1, 2024 Author

Amin-Yazdanshenas
Oct 29, 2024

Replies: 2 comments 8 replies

knmcguire
Oct 30, 2024

Amin-Yazdanshenas Oct 30, 2024
Author

Amin-Yazdanshenas Oct 30, 2024
Author

Amin-Yazdanshenas Oct 31, 2024
Author

Amin-Yazdanshenas
Nov 1, 2024
Author