Forces and energy in a system of a group of walkers

[Dassinia]

Hello,
I am studying a system of a group of walkers and how they behave.
There are four kind of forces:
- Repulsion between walkers
- A force modeled by the fact that all walkers gather into groups and walk in the same direction so their velocity are // that i will name S.
- "Autopropulsion" walkers move spontaneously in the same direction of the walker's velocity
- Random force in a random direction caused by uneven grounds, projectiles etc..

I want to know what forces give energy to the system and take energy from it

Just correct me if I'm wrong :
Repulsion and autopropulsion dissipate energy because after a certain amount of time the walkers don't move anymore
The force S and the random force give energy, the walkers keep moving, the kinetic energy increases.

Thanks

 

[cheah10]

First, are the walkers living things? If yes, then are the four forces caused by the intentional movement of the walkers? or are they forces due to nature?