RRA
-
Filipa Joao
- Posts: 7
- Joined: Thu Jun 12, 2008 8:45 am
RRA
Hi, I'm having some problems running the RRA tool. When it starts running, the torso sudenly bends and the feet start rotating. Then, all the body starts changing its position. What could be the reasons for this behaviour? Thanks for your support. Filipa
Filipa João
Biomechanics and Functional Morphology Laboratoire
Technical University of Lisbon - Faculty of Human Kinetics
Portugal
Biomechanics and Functional Morphology Laboratoire
Technical University of Lisbon - Faculty of Human Kinetics
Portugal
-
Ayman Habib
- Posts: 2248
- Joined: Fri Apr 01, 2005 12:24 pm
RE: RRA
Hi Filipa,
There are many potential issues but the first suspect would be to check the "Actuators and External Loads" tab and make sure that you've checked "Replace model's actuator set" (similar to our setup files) if running RRA.
I can't tell if it's a bug or not without seeing your model, data and setup files.
Good luck,
-Ayman
There are many potential issues but the first suspect would be to check the "Actuators and External Loads" tab and make sure that you've checked "Replace model's actuator set" (similar to our setup files) if running RRA.
I can't tell if it's a bug or not without seeing your model, data and setup files.
Good luck,
-Ayman
-
Hossein Mokhtarzadeh
- Posts: 37
- Joined: Sun Dec 13, 2009 9:44 pm
RE: RRA
I have the same problem while I am doing RRA. My model is for landing manuvoure. I check everything like CoP, forces,and http://wiki.simtk.org/opensim/rraCmcPag ... =%28RRA%29
Do these recommendations work by trial and error?
is there any good path to go through and debug the model?
Do these recommendations work by trial and error?
is there any good path to go through and debug the model?
-
Anders Sandholm
- Posts: 30
- Joined: Thu Feb 22, 2007 1:53 pm
RE: RRA
Hi
(I wrote this for a while ago, just posting it again, it might help you out. It took me a bit of work to nail down all the parameters for CMC and RRA)
Most (read all) of these suggestions I got from Ayman Habib, so all credit should go his way.
Its no internal ranking between the ordering, you probably have to look into all points to get a good solution and understand the RRA and CMC.
1: Read the homepage http://wiki.simtk.org/opensim/rraCmcPage
2: Check your ground reaction force, does it align up with the correct time frame
(you can read the mot file into matlab)
3: Check again your ground reaction force, is it described correctly in the OpenSim coordinate system? Compare to the motion capture software, maybe an axis is point in the wrong direction.
4: check your model and setup files, like Actuators and Task. Have you looked or unlocked any joints in the model file? If so, you have to change these file so everything match. Like the subtalar or mtp joint.
5:Center of mass
AFTER the scaling you have to open the model file (osim) and copy the center of mass (COM) for the pelvis. This because when you scale the model the COM moves).
For RRA:
Before running the RRA you have to copy the new COM into the RRA Actuator files. (see further down for example)
For CMC / after RRA (or if you go direct from scaling to CMC)
The RRA gives you a new model file, with a new COM, so again open the file, copy the COM and past the new value into the actuator file.
(so if you run both RRA and CMC you have to do it twice)
Example:
In the osim file, in <Body name="pelvis"> you have something like this
<mass_center> -0.07357895 0.00000000 0.00000000 </mass_center>
copy these values and past them into the actuator file in the point_B node (they stand for FX, FY and FZ)
<Force name="FX">
<optimal_force> 100.00000000 </optimal_force>
<body_A> ground </body_A>
<point_A> 0.000 0.000 0.000 </point_A>
<direction_A> -1.000 0.000 0.000 </direction_A>
<body_B> pelvis </body_B>
<point_B> -0.0724376 0.00000000 0.00000000 </point_B>
</Force>
6: kp and kv parameters, if the motion is fast you might have to increase these, see the manual and homepage for equation.
7: Weights, there are plenty of them, use higher values of joints/markers you are confident in. Check your IK solution, is this what you want. Does you motion need the mtp or subtalar joint?
8: In the Actuators file, you have reserve actuators (read OpenSim users guide for more info about these) enable them, except for the joints you have locked.
The idea is that you should not need these, but sometime the model is not strong enough, and this give it some extra force, but read the manual for more info.
9: The Setup file,
read and take a look of the following parameters
maximum_number_of_integrator_steps
maximum_integrator_step_size
integrator_error_tolerance
integrator_fine_tolerance
optimizer_max_iterations
for CMC also make sure that
adjust_com_to_reduce_residuals is set to false
(I wrote this for a while ago, just posting it again, it might help you out. It took me a bit of work to nail down all the parameters for CMC and RRA)
Most (read all) of these suggestions I got from Ayman Habib, so all credit should go his way.
Its no internal ranking between the ordering, you probably have to look into all points to get a good solution and understand the RRA and CMC.
1: Read the homepage http://wiki.simtk.org/opensim/rraCmcPage
2: Check your ground reaction force, does it align up with the correct time frame
(you can read the mot file into matlab)
3: Check again your ground reaction force, is it described correctly in the OpenSim coordinate system? Compare to the motion capture software, maybe an axis is point in the wrong direction.
4: check your model and setup files, like Actuators and Task. Have you looked or unlocked any joints in the model file? If so, you have to change these file so everything match. Like the subtalar or mtp joint.
5:Center of mass
AFTER the scaling you have to open the model file (osim) and copy the center of mass (COM) for the pelvis. This because when you scale the model the COM moves).
For RRA:
Before running the RRA you have to copy the new COM into the RRA Actuator files. (see further down for example)
For CMC / after RRA (or if you go direct from scaling to CMC)
The RRA gives you a new model file, with a new COM, so again open the file, copy the COM and past the new value into the actuator file.
(so if you run both RRA and CMC you have to do it twice)
Example:
In the osim file, in <Body name="pelvis"> you have something like this
<mass_center> -0.07357895 0.00000000 0.00000000 </mass_center>
copy these values and past them into the actuator file in the point_B node (they stand for FX, FY and FZ)
<Force name="FX">
<optimal_force> 100.00000000 </optimal_force>
<body_A> ground </body_A>
<point_A> 0.000 0.000 0.000 </point_A>
<direction_A> -1.000 0.000 0.000 </direction_A>
<body_B> pelvis </body_B>
<point_B> -0.0724376 0.00000000 0.00000000 </point_B>
</Force>
6: kp and kv parameters, if the motion is fast you might have to increase these, see the manual and homepage for equation.
7: Weights, there are plenty of them, use higher values of joints/markers you are confident in. Check your IK solution, is this what you want. Does you motion need the mtp or subtalar joint?
8: In the Actuators file, you have reserve actuators (read OpenSim users guide for more info about these) enable them, except for the joints you have locked.
The idea is that you should not need these, but sometime the model is not strong enough, and this give it some extra force, but read the manual for more info.
9: The Setup file,
read and take a look of the following parameters
maximum_number_of_integrator_steps
maximum_integrator_step_size
integrator_error_tolerance
integrator_fine_tolerance
optimizer_max_iterations
for CMC also make sure that
adjust_com_to_reduce_residuals is set to false
-
Hossein Mokhtarzadeh
- Posts: 37
- Joined: Sun Dec 13, 2009 9:44 pm
RE: RRA
Hi Anders,
Thank you for your great comments.
I could do RRA for part of my model after striking the force plate. I tried to stop using GUI and it works much better. I actually modified COM as you mentioned. I am trying to solve it when foot strikes the force plate.
Many thanks
Hossein
Thank you for your great comments.
I could do RRA for part of my model after striking the force plate. I tried to stop using GUI and it works much better. I actually modified COM as you mentioned. I am trying to solve it when foot strikes the force plate.
Many thanks
Hossein
-
J.J. Mordang
- Posts: 26
- Joined: Mon Mar 22, 2010 7:04 am
RE: RRA
Hi,
Currently I'm busy with a model of the right leg. I've added 3 more joints to the foot to see what happens during normal gait. I wanted to do a RRA simulation and I read the rraCmcPage and the suggestions in the former post but the simulation still won't work properly. When the RRA simulation is finished the result is that the the model is transformed along the x,y and Z axis as one rigid body and no joints have been used.
The Inverse Kinematics and the inverse dynamics looks just fine.
Can anyone suggest what I'm doing wrong?
Thank you very much for your time and help!
Kind regards,
Jan-Jurre
Currently I'm busy with a model of the right leg. I've added 3 more joints to the foot to see what happens during normal gait. I wanted to do a RRA simulation and I read the rraCmcPage and the suggestions in the former post but the simulation still won't work properly. When the RRA simulation is finished the result is that the the model is transformed along the x,y and Z axis as one rigid body and no joints have been used.
The Inverse Kinematics and the inverse dynamics looks just fine.
Can anyone suggest what I'm doing wrong?
Thank you very much for your time and help!
Kind regards,
Jan-Jurre