**4. Conclusions**

The design, development, and construction of a low-cost laboratory test bench suitable to analyze agricultural spray nozzles according to the ISO 5682-1 procedure were discussed in the paper. The preliminary tests show its usefulness under several aspects:


The system also has some limitations due to the specific hardware implementation. The most severe limitation is imposed by the rail length, which does not allow for the maximum speed of the mobile platform, while spraying above the Petri dishes, to be higher than 1.5 m/s. Higher speed values to be kept constant while the nozzle sprays above the Petri dishes would require higher acceleration values, but the maximum acceleration is limited for mechanical/electrical safety reasons. Increasing the platform speed is a practical way to reduce overlaps between drops and then to simplify the subsequent image analysis procedure.

A minor limitation is related to the maximum sample rate of the Advantech Ethernet modules, used for monitoring the position and speed profile and for acquiring data from sensors. The trajectory control loop is achieved via hardware with a 1 kHz sampling frequency, but monitoring and logging operations are left to the Windows operating system, which cannot guarantee a constant sampling rate and good accuracy for time intervals less than 100 ms; thus, the speed and position graphs may result deformed. An optimization of the reading and writing routines and of data filtering may improve these aspects.

Finally, a significant improvement may be introduced in the camera positioning system. The camera is actually applied to a metallic frame, which in turn is manually hanged to the rails in predetermined positions. A better solution could be to hang the camera directly to the mobile platform after the spray passes and then to position it in correspondence of the Petri dishes by exploiting the control position system of the motor. This could speed up the image acquisition procedure and then reduce any effect of external factors.

Finally, taking into account all the above considerations, it is possible to conclude that the main objectives fixed were achieved with the test bench and that its modularity allows for further developments to overcome the limitations highlighted, without compromising the low cost.

**Author Contributions:** Conceptualization, E.C., D.L., G.M., and R.P.; methodology, E.C., D.L., G.M., and R.P.; software, D.L.; validation, E.C., D.L., G.M., and R.P.; formal analysis, E.C., D.L., G.M., and R.P.; investigation, E.C., D.L., G.M., and R.P.; data curation, E.C., D.L., G.M., and R.P.; writing—original draft preparation, E.C.; writing—review and editing, E.C., D.L., G.M., and R.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was carried out within the research project "Contributo della meccanica agraria e delle costruzioni rurali per il miglioramento della sostenibilità delle produzioni agricole, zootecniche e agro-industriali. WP1: Impiego sostenibile di macchine irroratrici in serra e in pieno campo", financed inside the "Linea di intervento 2-dotazione ordinaria per attività istituzionali dei dipartimenti-2016-18-II annualità" of the University of Catania.

**Conflicts of Interest:** The authors declare no conflict of interest.
