A body impedance-based safety system for electrical pruning tools.

The use of high productivity pruning shears led the market toward the development of electronic controlled pneumatic or electric tools, which improve the ergonomics and the effective field capacity. A vineyard worker can get to make up to 8-10.000 cutting shares per working day. Nevertheless, the high intensity and repetitiveness of the movements, which shall be added to the limitation of workspaces with the constrain of a high precision cuts, gives rise to main two issues i.e. the primary on the safety for the operator, the other related to the potential plant damage. Investigation concerning such tools provided by National Institute for Insurance against Accidents at Work - INAIL have highlighted for the agricultural sector, on average just under 200 accident per year of partial or sharp cuts of the phalanges. Similarly, a further problem which occurs during the pruning stages in vineyards, is the accidental cutting of trellis wires. On the market, are available some safety systems which, however, do not spread because the non-user-friendliness. After all, the innovations in electronic technology allow realizing devices that can discriminate at any instant and with great accuracy, what is touching the blade of the scissors and lock it if necessary. The present work relates the preliminary evaluation of a safety kit applicable to electrical portable tools with trigger activation or similar progressive regulators. It is made of a safety circuit that interacts with the electronic controller of the tools by using the natural body impedance measurements. An electrical control allows to immediately detecting the materials impedance that come into contact with blade. When accidentally the operator finger's is touching the blade, the impedance value go down quickly, consequently the voltage reading will drop towards a threshold value where a decision block will intervene to stop the closing movement of the blades. The preliminary tests carried out showed the high reliability of the safety stop system, which could represent a feasible active solution for every electrical supplied cutting tools employable in agriculture sector and not just.