Bohmian Mechanics (Stanford Encyclopedia of Philosophy) :
It is the simplest example of what is often called a hidden variables interpretation of quantum mechanics.
The wave function provides only a partial description of the system. This description is completed by the specification of the actual positions of the particles. The latter evolve according to the “guiding equation”, which expresses the velocities of the particles in terms of the wave function.
Measurement emerge from an analysis of the two equations of motion: Schrödinger’s equation and the guiding equation (it postulates an actual configuration of particles exists even when unobserved).