kinematically indeterminate


I am trying to create a model which drives a recumbend bicycle. Therefor I use a changed „Pedaldemo“ from AMMRV1.4.1.
The model seems to be loading fine but when I tried to run it, it says that it is kinematically indeterminate.
I don´t know what´s the problem. Can you help me?

Thank you

Hi Klaudia,

I had a look at your model and you have 111 constraints and 112 unknown, so one DOF is undefined. Unfortunately I cannot say which one is missing. It looks like drivers are mixed up and certain segments are constraint twice, so it is hard to me to get along.
I would suggest that you start with the bike3D model and it should be quite easy to get a different body position. I remember that a student from Netherlands made that once before.
Then change the model step by step, reload and rerun the model after every step, so you’ll find bugs immediately.
If you want to stick to this PedalDemo model, then the best thing to do is make a sketch of your segments (stig figure) and define DOF and drivers/constraints. Then compare the sketch with what you have.

Hi Amir,

I´ve tried it with BikeModel3D.
Just now I don´t know how to change the positon of the ankle and knee.
After few steps the left knee goes to left side and both feet still have the position like cycling.
Where I can change the position of the foot?

best regards,

Hey Klaudia,

the position of the body is defined by drivers. The Pelvis is fixed to the SaddlePos, and the Foot to the crank with drivers in the JointsAndDrivers.any. The SaddlePos and the CrankPos are defined in the BikeFrameAndWheels.any. I would suggest to outcomment the bike frame, move the SaddlePos to the back and leave the Crank where it is. additional change in the mannequin pelvis and trunk posture…

Do everything step by step, reload and rerun after every change, so you can see if something did go in the wrong direction.

Hey Amir,

I have done it, what do you write me. Nevertheless, the feet behave differently than expected and I don´t know why. You can see it in the posted “”

Best Regards,

Hi Kaludia,

I have corrected a few things:

In the main file i have moved the saddel pos.

In the BikeFrameAndWheel i have moved chnaged the CrankJoint to be at 0,0,0 it was not symetric before.

In the JointAndDrivers search for the comment //ST and you will see the changes. There is a change related to the ankel/peldal angle and there is a change related to the control of the knee.

Best regards

It´s running!

Thank you very much