Volitional mechanics has four stages, which are each part of   
the cycle of a perpetual motion machine

Volition - Volition
is represented by the highest point of
motion for the most mobile units, and the application of
mass and / or momentum that happens afterwards. It
expresses the machine's potential energy and general
energy principle.

Devescension - This period shows the machine's ability to
recover some portion of its motion automatically. It typically
involves transport by downward-sloping ramps, which mirror
other upwards or downwards sloping ramps.

Devolition - This incorporates both the period of devescension
and the period of vescension. It may be used as a name for
the strategy of returning to a high altitude.

Vescension - During this period, which may be a long, rising,
mostly horizontal motion, the device attempts to recover
the remainder of its energy by gaining momentum.

In devices incorporating the four periods as above, it may be
observed that such devices make use of the following equations:

Hypothetical Volitional Energy =
   Mobile Units / Dual-Axial Units

Hypothetical Volitional Equilibrium =
Mod. Units / (Stems Per Cycle / Sub-Cycles Per Cycle)

Volitional Efficiency or Relative Unity Rating =
Volitional Energy / Volitional Equilibrium

In general, there are two requirements:

               1. Motion from rest at no cost, and

               2. Extractable energy.

And the general principle is something like,

       "Momentum without inherent velocity".