====== Equilibrium-Point Control ======

^ Autors | Pohl Steffen & Manglkammer Philipp |
^ Betreuer | Marc Jacob |
^ Bearbeitungsdauer | ca. 25 Stunden |
^ Präsentationstermin  | dd.mm.yyyy |

<note tip>
You can find more information following the next links:
  * Wiki page ** formatting **: [[https://www.dokuwiki.org/wiki:syntax#formatting_syntax|HowTo - Wiki-Format]]
  * Creation of a **video-podcast ** [[http://wiki.ifs-tud.de/howto|HowTo - Podcast]] 
</note>

===== Introduction/Motivation =====
Basic EP-concept (EP = Equilibrium point)

- The EP-Control System states, that a set of two actuators can act like a human muscles Agonist/Antagonist principle.

- The applied force depends on muscle length and stimulation: The longer the artificial muscle, the more effective the stimulation in translated into force

- The system is heading towards a certain joint angle depending on the realation of force and length of both actuators

- Once the angle is reached, the joint stiffness can be modified by equally increasing or decreasing the applied forces in the actuators. 

- In our experiment, the used software defines sitffness and angle of the models joints which are automatically are translated in poses. Each of these poses define an Equilibrium Point

===== Podcast =====

Movement approaches via poses:

- The first set of poses was designed to be as detailed as possible and utilized every possibly relevant angle

- The second set only used simple movement patterns. The more complex movements then resulted from the passive mechanics of the muscle system

Resulting movement:

- the first set of poses result in failure due to loss of balance

- the second set shows a good result even without specific modelling

{{ :m3_seminar:m3_seminar_2019:projects_ustutt:biorobotikpodcast.mp4 |}}
===== Summary =====
At the end, three conclusions were reached:

1. The system is able to head towards a target position without the need for an inverted model

2. Using rough and simple movement patterns looks more natural and is more stable

3. A comparison between both approaches rises the question whether biological movement is also just a product of simple, prototypical poses instead of detailed motions

===== References =====
  - Bayer, A., Schmitt, S., Günther, M., Haeufle, D.F.B. (2017): The influence of biophysical muscle properties on simulating fast human arm movements. Computer Methods in Biomechanics and Biomedical Engineering 20(8), 11-24. https://dx.doi.org/10.1080/10255842.2017.1293663
  - Christensen, K. B., Günther, M., Schmitt, S., Siebert, T. (2017): Strain in shock-loaded skeletal muscle and the time scale of muscular wobbling mass dynamics.  Scientific Reports 7(1), 13266. https://dx.doi.org/10.1038/s41598-017-13630-7