Analog computing by ascribing meaning to motion, and cognizant of directions (in this case); while the bar may be 'just sitting there', an embedded device within, imbued with a human way ('intelligence') of 'reasoning' about lateral movements would be able to support decision making.
Take another analogous case of a twig moving in a brook: the twig doesn't 'need to know' the parameters of water flow in a brook as humans do, to determine which way to turn and tumble as it meanders through the water; it need not care about 'calculations' of water pressure, the topology of the ground beneath, obstructions in its path, spin induced by local eddy currents and what not to merrily cruise along; from a human perspective, an immense amount of computation (should) be involved.
Yet, as the water rolls along, equations of continuity needn't be solved, no moments need be calculated, as pure physical properties and forces do the trick.
Lot to learn from analog computing: digital computing is after all, a subset of it at the electronic level, could one say? :-)