Worker monitoring and protection in industrial production lines require advanced sensing capabilities and flexible solutions that are able to monitor the movements of the operator in proximity of moving robots. Considering that, in the context of human-robot collaborative (HRC) workplaces, no single technology can currently solve the problem of continuous worker monitoring, we propose the combination and transformation of multiple sensing technologies into a multisensory cloud-edge platform for passive sensing and perception. Multidimensional data acquisition, from different sources, pre-processing, manipulation, feature extraction, data distribution and fusion, along with distributed learning and computing methods are described. The platform proposes a practical solution for data fusion and analytics obtained from distributed heterogeneous sensor devices, that perform the opportunistic perception of the worker through radio signals, including WiFi, radars working in the sub-THz band and infrared sensors. The proposed platform performance is validated through real HRC use case scenarios inside a pilot industrial plant in which operator safety is guaranteed.