As I said last time,the Fourier driver is working now, this allows me only in kinematic analysis to make the internal and externalrotation.
When I simulate in inverse dynamic analysis, i have always this error:" [SIZE=1]
ERROR(OBJ1)[/SIZE] : [SIZE=1]C:/D…s/s…e/M…s/A…y/R…1/A…n/E…s/R…r/Echantillon.Main.any[/SIZE] : ‘MyStudy’ : Muscle recruitment analysis failed, simplex solver reports that solution does not satisfy all constraints."
I change the contraints in different places of the model, but noting. What can i do to make an internal and externalrotation in Inverse dynamic analysis?
I sent you the anyscript for this model to help me to find the problem.
The problem is located in the part of the script you was thinking about, with the driver KeyRotAConstraint. The Reaction.Type of this driver is switched Off which means that there is nothing holding the two Rotameterkey segment rotations.
Those rotations have to be carried somehow, if not the inverse dynamic analysis is not possible.
So i don’t know how is working in reality this device you are modeling, but maybe it is fixed to the leg or to the floor (in that case you can just turn On the reaction.Type).
Once you have provided the realistic boundary conditions for the device the model should run ok.
I have made many changes to the model by letting down the Reaction.type on Off, because I wanted the muscular motion exercises only. I did not know that the Reaction.type also had this feature.
As soon as I switched the Reaction.type on ON, then the dynamic analysis has worked, but I have to optimize it because I think the muscle activity ist not good.
Please, I read more the tutorial, but if you have more about the features of the Driver, could you sent me?
I thing the movement and the muscle activity are better now, but when I simulate with the Mus 3E, the calibration ist going well but the dynamic analysis ist going bad and indicates:
Inverse Dynamic Analysis (Operation: Main.MyStudy.InverseDynamicAnalysis):
0) Design variables have been updated.
Load time positions have been re-established. [SIZE=1]ERROR(OBJ.MCH.KIN2)[/SIZE] : [SIZE=1]C:/D…s/s…e/M…s/A…y/R…1/A…n/E…s/R…r/Echantillon.Main.any[/SIZE] : ‘MyStudy’ : Model is kinematically over-constrained : Position analysis failed : 20 unsolvable constraint(s) found
[SIZE=2]I don’t understand how we can have 20 unsolvable constraints and the simulations with “BodyModel_Nomuscle and BodyModel” are very good.[/SIZE]
[SIZE=2][/SIZE]
[SIZE=2]How can I do, because I want to know more about the Mus 3E.[/SIZE]
[SIZE=2][/SIZE]
[SIZE=2]Best regards[/SIZE]
[SIZE=2]Simon
[/SIZE]
What happens is that you included the calibration in the Study. If you look at the structure of the repository models you will see that in the main file there are two folders: HumanModel and Model. This separation is important for the calibration.
Notice that the calibration is included in the HumanModel folder and only the Model folder with a reference to the BodyModel is part of the study. So this has the effect of leaving the calibration out of the study.
But you have changed that structure in your model: your study includes the Echantillon folder wich itself includes all the HumanModel folder (and therefore the calibration).
So i think you should modify your model to follow the usual structure of the repository models to avoid such kind of problems.
Hi Sylvain,
[LEFT]I put the cross ligaments in my model. During the various tests, I found that the values (eps1, F1) as defined in Chapter ligaments significantly influence the strength in the ligament. To determine whether the forces obtained are close to reality, I want to know how you obtained these parameters (eps1,F1) as you define as the stiffness of the ligament. Is it when testing mechanical or …?
This is a very good question. You are right that those parameters are very important since they influence a lot the strength of the ligament and therefore the recruitment of the muscles around it. the problem is that there is very little information about the ligaments in the literature.
We actually didn’t include the ligaments yet in our models because we don’t have reliable data to model them. The values in the tutorial are estimated. It would definitly be a good solution to do some experiments to test the mechanical properties of the ligaments.
Hello sylvain
I have many confusion about strength, muscle activity.
About the strength can you explain me exactly what is it? And what is the difference with force? I read in tutorial but I don’t grasp his meaning. Besides when man said: muscle strength decreases with the contraction velocity, so that muscles contracting quickly have less strength than muscles contracting slowly. I try this with the elbow joint of my upper limb but I don’t grasp something.
About the muscle activity, when we make an electromyography of the muscle, can we compare this to the muscle activity in ANYBODY? And when in ANYBODY, man define a muscle activity as a muscle force divided by strength. Can I have more explanation about?
please I will very happy to have your explanation about.
The strength of a muscle is the maximum force a muscle can exert under the given circumstances. Simple muscle models presume that the strength is constant. More detailed models, such as the three-element model in AnyBody, take the influence of the current length and the current contraction velocity into account.
The muscle force is the force that the muscle is actually exerciting. Muscles are not always 100% loaded, so the force is usually smaller than the strength.
Muscle activity in AnyBody is not exactly the same as EMG. For static situations you can probably compare them but not in the dynamic case. Some part of the EMG is related to the force development and thereby to the muscle activity as computed by AnyBody, but when the muscle is moving, there are more things than just force production going on that influence the EMG signal.