OpenSim - Science topic

I am a PhD student in ergonomics conducting research on lower limb biomechanics in real-world work environments. I am using a motion capture system and lower limb EMG to collect data during standing work tasks, where the use of force plates is not feasible.

My objective is to analyze the biomechanics of the lower limbs with and without an exoskeleton using OpenSim. However, I am unsure if performing inverse dynamics analysis is possible without force plate data.

Thank you in advance

I am collecting data on the upper limb using IMU from the Cometa System.

I am having difficulties preparing my data to be used for OpenSim. The joint movement in OpenSim does not follow what it should. I really need help in understanding and solving this issue.

the ERROR was reported as:

SimTK Exception thrown at InteriorPointOptimizer.cpp:264:

Optimizer failed: Ipopt: Infeasible problem detected (status 2)

OPTIMIZATION FAILED...

CMC::computeControls: Optimizer could not find a solution.

Unable to find a feasible solution at time = 0.49( both feet stroked).

Model cannot generate the forces necessary to achieve the target acceleration.

Possible issues: 1. not all model degrees-of-freedom are actuated,

2. there are tracking tasks for locked coordinates, and/or

3. there are unnecessary control constraints on reserve/residual actuators.

to solve this problem ,i had double checked Possible issues 1-3 above, however it did't work.

thanks for your advices,and if you get interested in this problem, please do not hesitate to leave your massages.

Hello! I would like to know if there is a way to convert my Visual3D model/files into opensim software through matlab?

I no longer have access to visual3D, but would like to extract my visual3D model into opensim. I have found a matlab package which will permit me to convert my c3d files to osim .mot files, which works perfectly!* But I would like to know if there's a way to also bring across the model into opensim using matlab? The model is currently saved as both a cmz and a cmx file format. Thank you so much in advance for any advice offered :)

*also: the package I found does this one by one in matlab. I have 13,000 c3d files. Is there a batch-process function out there?

Hi everyone!

I'm trying to do Static Optimization in Opensim, loading the .mot file I obtained from IK tool in Opensim.

The SO starts, but seems never to ends.

How can I manage it?

Thank you in advance,

Anna :)

I want to know how to get the interface between opensim and matlab when I have a file on (.osm) and I want to transfer it to matlab using s-function

I read paper (A platform for dynamic simulation and control of movement based on OpenSim and MATLAB.

Mansouri M1, Reinbolt JA.)

in figure(3) he mention about interface on s-function, but I do not know how it is work , please can you help me with it

thanks for everything

I would like to create Mex file as stated on this website [https://simtk.org/projects/opensimmatlab].

Does anyone has worked on this project? I have some questions.

Hi to everyone!

I need to obtain the tendon force of certain muscles of the right upper limb after that the subject exerted a force. I found out the Anlyze tool of OpenSim gives as output a file with the tendon force obtained applying external forces but to run this tool I need a file I can't write.... This file can be obtained using Computed Muscle Control tool, I tried but it continues saying "SimTK Exception thrown at InteriorPointOptimizer.cpp:261:

Optimizer failed: Ipopt: Infeasible problem detected (status 2)

OPTIMIZATION FAILED...

CMC.computeControls: ERROR- Optimizer could not find a solution.

Unable to find a feasible solution at time = 5.

Model cannot generate the forces necessary to achieve the target acceleration.

Possible issues: 1. not all model degrees-of-freedom are actuated,

2. there are tracking tasks for locked coordinates, and/or

3. there are unnecessary control constraints on reserve/residual actuators."

I can't reach a solution...

Can you help me?

Thank you very much!

Anna

Good Afternoon,

I am trying to obtain the tendon forces of some muscles using a musculoskeletal model on OpenSim. The person ha applied a force to a sensor, then I have done the Inverse Dynamics applying the external forces and after that I plotted the tendon forces vs time but the software advise me that it is applying the external forces and I don't understand the reason?

Can someone help me?

Thanks!

Anna

In order to study bone fracture in patients with osteoporosis, I need patient's exact muscle forces magnitude, location and direction (as FEM boundry conditions), while it is difficult to get such subjects to a MOCAP lab and get their data.

1. Is it possible to get a body-matched subject perform our tasks of interest (gait, stairs decent/accent, etc) and use their MOCAP data to run our multi-body dynamics simulation (using OpenSim software)?

2. How reliable would be the calculated muscle forces in terms of magnitude and direction?

3. Is there any other way to derive these patient's muscle forces? how accurate would be the results of these alternative methods?

Best regards

Yunus.

How we can access individual marker errors during inverse kinematics in OpenSim?

In the message window only total marker error and marker error: RMS has shown but we want to know the errors of each marker during motion when we use inverse kinematics in OpenSim.

I wanna analyze forces between an ExoSuit and a Human for improving its design in terms of efficient actuation and safe interaction with the user. so I should derive a mathematical model. but:

Can force obtained from EMG be compared with force obtained from computed muscle control in opensim?

I am developing OpenSIM model of pediatric shoulder joint. The main focus is to characterize biomechanics of a shoulder with obstetrics brachial plexus palsy. The data I have is MRI and motion analysis for different activities. No EMG and no MVICs.

So, in the model, how do I assume the optimal fiber length values for shoulder musculature? Does anyone know any relevant literature?

OMNeT++ Discrete Event Simulation (C) 1992-2016 Andras Varga, OpenSim Ltd.

Version: 5.0, build: 160414-aa4629c, edition: Academic Public License -- NOT FOR COMMERCIAL USE

See the license for distribution terms and warranty disclaimer

Setting up Tkenv...

Loading NED files from .: 7

Loading images from D:\omnetpp-5.0-src-windows\omnetpp-5.0\images: *: 0 abstract/*: 90 background/*: 4 block/*: 320 device/*: 195 logo/*: 1 maps/*: 9 misc/*: 70 msg/*: 55 old/*: 111 status/*: 28

Plugin path: ./plugins

RUNTIME ERROR. A cRuntimeError exception is about to be thrown, and you

requested (by setting debug-on-errors=true in the ini file) that errors

abort execution and break into the debugger.

You should now probably be running the simulation under gdb or another

debugger. The simulation kernel will now raise a SIGINT signal which will

get you into the debugger. If you are not running under a debugger, you can

still use the core dump for post-mortem debugging. Once in the debugger,

view the call stack (in gdb: "bt" command) to see the context of the

runtime error.

<!> Error in module (omnetpp::cModule) Network.node[418] (id=420) during network setup: Cannot create coroutine with 16384+49152 bytes of stack space for module `' -- see Manual for hints on how to increase the number of coroutines that can be created, or rewrite modules to use handleMessage() instead of activity().

TRAPPING on the exception above, due to a debug-on-errors=true configuration option. Is your debugger ready?

In virtual learning environments (e.g. Moodle), or in virtual worlds (e.g. OpenSim), the interaction of students can be tracked in several ways. This can help the teacher with the objective of knowing the level of interaction that such student had in the environment.

Can anyone give examples of papers with tracking of students in Moodle or Virtual Worlds?

I use S function in matlab ,it get opensim file but error in initial callback, how i check in model properties initial callback?

Thanks in advance for your replies.

We have made available a few tools that is currently available for you to try out. This may be of interest to folks involved in VR, VR applications research, instructional technology. At the very least, I think our approach may be of interest.

And while trying the tools, why not capture what you make and send us a screen shot, or video, we have organized a competition to reward entries based on public votes. More information at link below