NOVELTY - The compressor has a stator housing (20) with an interior bore, and two endplates (10, 30) connected to the housing. A rotor (40) has a rotor shaft (100) located in the bore, where an end of the shaft is connected to an external power source for rotating the rotor within the bore. A vane centering device connects a rotating vane assembly to the shaft and centers a vane (50) with respect to the rotor. A rotor centering device has a roller bearing (60) to control a radial position of the assembly, and the vane centering device has control rods (90) to control the position of the assembly.    USE - Used as a reversible refrigerant compressor, miniature compressor and miniature vacuum pump (claimed), for a fuel cell application that is utilized in a transportation vehicle e.g. car, truck and bus, life science, semiconductor processing, medical device, vacuum pump application and pond aeration system at golf course.    ADVANTAGE - The roller bearing of the rotor centering device controls the radial position of the rotating vane assembly, and the control rods of the vane centering device controls the axial position of the assembly, thus preventing contact of the vane with the stator housing interior bore and the two endplates, and hence providing the compressor with reduced friction, efficiency enhancement and exceedingly long operating life. The prevention of the contact of the vane thus insures that the gas processed by the compressor has only minimal leakage during inlet, compression and discharge, and hence improving efficiency of the compressor.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a system for controlling a repetitive internal motion to prevent moving parts from contacting non-moving parts of an apparatus comprising a stator housing    (2) a method for controlling repetitive internal motion of a rotor and a vane within a compression chamber of an apparatus.    DESCRIPTION OF DRAWING(S) - The drawing shows a front view of an orbital monovane device.    Inlet manifold (5)    Discharge manifold (15)    Stator housing (20)    Rotor (40)    Vane (50)    Glider races (62)    Vane axle (70)    Control rod (90)    Rotor shaft (100)    Ball bearings (110)