An assembly is disclosed for adjusting the position of a solar array or device to enable it to maintain a desired solar energy reception throughout each day’s operation of the assembly. The errors have traditionally been minimized by enclosing the machine in a thermal enclosure, by careful calibration, or by mounting a laser interferometer on each axis. The outer wall constitutes at least part of an outer contour of the housing. The method includes selecting, at each station, one or more probing channels for the transmission of probe signals to other stations. On an appropriate location of the bottom of the second magnetic unit, a transverse beam extends.