Dear AnyBody members!
I would like to post my conversation with Soren from the AnyBody Support, which I led on the private chat. So from now on everybody can benefit from the answer he gave.
[i]I need your help with trying to change some specific things on the KneeLoad Model. Here I must especially mention that I am an absolute beginner.
First I want to explain what I intend at all. I want to modify the KneeLoad model that the body is seated in a leg press (just the position/posture), pressing against a rigid force plate.
But after working with that I have a few questions:
- Just to clear out what the Model actually does! The Model investigates the connection be-tween knee shear force and foot center of pressur. What does that actually mean?
And what about the movement that takes place in front of it? Is the investigation depending on the movement or does it also works without movement?
If yes and I will remove the movement and set the model to the desired position, does the model then anything? I mean there is a file which calls “Environment”. I don´t understand exactly the sense of this AnySript code. Can I adjust the pressure against the foot in this folder or the pressure against the force plate? So that the Model would do something without movement.
Please could you explain this AnyScript code (see figure Environment)?
- I modified the position of the Model in the folder “Mannequin” already. But it changes al-ways after “RunApplication” to a position that I don´t understand (from position1 to posi-tio2, see figure position1, position2). How can I fix that?
Do I have to modify something else?
- What do I have to change to remove the movement?
I hope this is clear explained! If you don´t understand something, please let me know!
Thank you in advance![/i]
Answer of Soren:
Welcome to the forum.
This model we no longer distribute with the repository, i will try to answer your questions the best i can.
1: The model is loaded by a force applied to the foot, this force moves throughout the analysis from the heel to the front. The knee joint is a revolute joint, and the anterior/posterior reaction of the this joint is referred to in the description of the model as shear force. So when looking at the reaction force in the joint you will see this changing as a consequence of the change in the load.
The script you have listed is how the load is being applied. It introduces a segment which is connected to the foot through a prismatic joint, then a force is applied to the segment. This force is transmitted through the prismatic joint to the foot.
If you change model so that the force does not move you will get a constant/static output from the model, this is ok.
The mannequin values are used to set the initial conditions for the model, this is how the model will load. Once the model is being used these values may not be used for actually driving the model, this depends on the actual model. Since you see a differences between a loaded model and after running it means that these values are not all used for driving the model
The loading position only used as the initial guess for the model, so it just needs to be good enough for the model to solve the first kinematic step, it has no further impact on the model than this. So it is ok to see a difference in load position and running position, as long the model actually solves without error.
I would recommend to start going through the tutorials these will take you through many of these things.
Secondly please do not send this type of questions as private messages this is not the intention of this forum ;-). We would like to help our users so that everyone can benefit from the answers we give. I can see that you have posted a second private message today, please re-post it as a normal post and we will look at as soon we can.