Creating and Moving Agents - Learning Game AI Programming with Lua - page 108

Wandering
A wandering behavior essentially returns a tangent steering force to the agent's forward
vector. Wandering is meant to add deviation to an agent's movement and is not to be used
as a steering force by itself. Taking in a delta time in milliseconds allows wandering forces
to change at a constant rate:
local forceToWander = agent:ForceToWander(deltaTimeInMillis);