Control of a unit mass
Consider the problem of transferring a unit mass at rest sliding on a plane from a point to another at a unit distance. We can exert a constant force of magnitude on the mass at time intervals
,
.
Denoting by the position at the final instant
, we can express via Newton’s law the relationship between the force vector
and position/velocity vector
as
, where
.
Now assume that we would like to find the smallest-norm (in the Euclidean sense) force that puts the mass at at the final time. This is the problem of finding the minimum-norm solution to the equation
. The solution is
.