I tried lots of trials(changed the initial motion, reduced the differences between red and blue markers, change markers set-up like Opt and Weight) but, errors above appeared again and again.
So, I compared fullbody mocap model in example folder and I found that there are at least 2 markers on 1 segment. Is it related to errors above?
It is a complex model with many degrees of freedom so it can be difficult to control.
The error indicates that the model fails in the first timeframe, this can be due to poor initial conditions or markers being wrongly placed etc.
Please try the following method.
[ol]
[li] Create model which is driven by joint angles drivers, so no makers, ensure that it runs kinematically.
[/li][li] Add one marker to the model and remove a joint driver which would control the same DOF
[/li][li] gradually add the markers back into the model and remove the joint drivers one by one always ensuring that you have a running model
[/li][/ol]
Thank you for your answer. I followed your method.
Actually, I did additional experimental work for motion capture. I added upper extremities markers (1 shoulder joint marker, 1 humerus marker, 1 elbow joint marker, 1 ulna marker).
I added all angle drivers for kinematics, and i was sure that it runs kinematically. and then, I added 2 markers (shoulder joint , humerus) . Next, I removed the shoulder joint driver and turn on the upperarmlength optimization. I ran motion and parameter optimization sequence. But, I had following messages;
Kinematic parameter analysis failed : there are 4 design variables but only 2 independent associated optimality conditions
I saw the chart about parameter optimization. There are 3 additional variables like upperArmX, Y, Z. So, it couldn’t get optimal upper arm length. How can I solve this problem?
I added all angle drivers for kinematics, and i was sure that it runs kinematically. and then, I added 2 markers (shoulder joint , humerus) . Next, I removed the shoulder joint driver and turn on the upperarmlength optimization. I ran motion and parameter optimization sequence. But, I had following messages;
This error means essentially the parameters you are trying to optimize is not bounded in the optimization. An example would be if you optimize humerus length and the elbow marker was free to change position. Then the optimizer would not know if it should change humerus length or move the marker, both would lead to the same results. So the error it looks like you need to constrain some of the markers not to be able to move by setting thé OptX--Z setting to OFF. The same error would appear in a model driven by joint angles if you tried to optimize the segments lengths.
Another comment when addind the markers and removing the joint drivers it is important that you remove the corresponding dof. So adding a elbow marker may mean that you can remove a driver for GH. Or adding an wrist driver may mean you remove elbow drivers etc.
[ol]
[li] There are additional design variables in the study… the error indicates this not issue
[/li][li] Mix up between left and right side… so markers on right and optimize left
[/li][li] Things not included in the study, are you sure the model parts you are using are referred or included into the study
[/li][li] If you have only one timestep it may also fail…i think
[/li][/ol]
If none of the above helps please upload the model, if possible
you do not need to add the joint angles as design variables.
In a mocap driven model the model is driven by the markers so the joint angles is a result of the tracking, this means there is no specific driver on the joint which needs to be added as design var.
I think you still have too many design variables somehow below is my explanation from earlier i tried to change it a little.
This error means essentially the parameters you are trying to optimize is not bounded in the optimization.
An example would be if you optimize humerus length and the elbow marker was free to change position. Then the optimizer would not know if it should change humerus length or move the marker, both would lead to the same results. So in this case you would have to lock the position of the elbow marker.
So the error it looks like you need to constrain some of the markers not to be able to move by setting thé OptX–Z setting to OFF. The same error would appear in a model driven by joint angles if you tried to optimize the segments lengths.
So if you have finger lengths as designvars and all marker positions on the finger as design on the finger it will lead to problems.
thank you for your answer again. I found how to solve this problem. As I said, I tried to adjust finger length as a design variable, so I added it in the optimal class. But I got error about optimal conditions. I found how to solve this problem. I made many mistakes. To scale the length, I had to add scale function of finger length and applied it to all points on the segment, but I haven’t applied it. no I can scale all finger segment length.
I have another question right now. I have c3d files for hand motion, and I’m trying to add markers on wrist . But I thought that there is something strange about radius position and rotation. As you can see, I think radius bone and ulna bone are not parallel. Distal part of radius bone is hanging out to dorsal direction. I wanted to attach markers on styloid process(acute part) of ulna and radius. But I don’t know where I have to attach markers. I compared to radius and ulna bone in Opensim software. In Opensim, two points(styloid process of ulna and radius)looks parallel. So, my conclusion is that the position of radius bone looks weired. Could you tell me any references about this problem? thank you for your attention.
It is difficult to place markers on the wrist because there is a lot of skin motion, you may want to consider to place these markers on the hand segment.
When comparing the two models it is important that the same pronation angle is used this will affect how this looks, also there are subject specific differences which will play a role.
You can read more about the arm model at our wiki page. www.anyscript.org