Prescribed movement in Forward Dynamic
Posted: Mon May 08, 2017 6:25 am
Dear All
I kindly ask you for help to solve the following problem.
I built a simple pendulum model, consisting of the following 2 rigid bodies (see attachment "pendulum.osim"):
- HEAD of the pendulum; visualized as a block
- ARM of the pendulum, visualized as a sphere in the mass center of the ARM
There are 2 joints in the model:
- The HEAD is connected to a ground with an free joint, whereas only the X-transnational movement is allowed.
- The ARM is is connected to the HEAD with an free joint, whereas only the Z-rotational movement is allowed.
My intention is to give a predefined transnational movement for the pendulum's HEAD in x-direction in function of the time, and calculate/simulate the corresponding rotational oscillation of the ARM with Forward Dynamic. For the definition of the movement of the HEAD, I would prefer a text file, providing the position in a given time step. I attached an example ("required motion of the pendelum head.txt").
As an alternative, less convenient solution a function for the x-movement of the HEAD could be defined, according to the attachment "predefinded motion.pdf". However, unfortunately I have no clue how such a function can be defined. Please tel me the "secret", if you know it.
I appreciate your help very much.
Best regards
Gabor
I kindly ask you for help to solve the following problem.
I built a simple pendulum model, consisting of the following 2 rigid bodies (see attachment "pendulum.osim"):
- HEAD of the pendulum; visualized as a block
- ARM of the pendulum, visualized as a sphere in the mass center of the ARM
There are 2 joints in the model:
- The HEAD is connected to a ground with an free joint, whereas only the X-transnational movement is allowed.
- The ARM is is connected to the HEAD with an free joint, whereas only the Z-rotational movement is allowed.
My intention is to give a predefined transnational movement for the pendulum's HEAD in x-direction in function of the time, and calculate/simulate the corresponding rotational oscillation of the ARM with Forward Dynamic. For the definition of the movement of the HEAD, I would prefer a text file, providing the position in a given time step. I attached an example ("required motion of the pendelum head.txt").
As an alternative, less convenient solution a function for the x-movement of the HEAD could be defined, according to the attachment "predefinded motion.pdf". However, unfortunately I have no clue how such a function can be defined. Please tel me the "secret", if you know it.
I appreciate your help very much.
Best regards
Gabor