A robotized environmental sensor array for gravitational wave observatory sites

A movable array of environmental sensors is intended for the feed-forward cancellation of the Newtonian noise generated by atmospheric density fluctuations and seismic displacements at the Virgo gravitational wave detector site, with the prospect of being used at the sites of future 3rd generation detectors. Each robot unit is equipped with a seismic sensor - optionally also a microphone and a magnetometer - for low-noise and low-frequency observations. The robots need to move autonomously in the experimental areas indoors, avoiding obstacles to reach the assigned positions where they start the data acquisition process. Then, the data will be transferred wirelessly to the control software that elaborates them and imparts to all robots the command to move to new optimal positions. Essential requirements of the system are accuracy in positioning and timing. The project is described highlighting the technical choices and their implementation.