| Popis: |
The market of the agricultural machineries has been recently modified due to globalisation, with an increasing of the competiveness and machinery reliability, and a reduction of cost production and development time. To perform this and, in particular to increase the reliability of the tractor, a tractor design correspondent to the real use on the machines is necessary. For these reasons the analysis of the tractor mission profile is one of the main objectives of tractor manufacturers. The mission profile of the tractor has usually been estimated through the use of questionnaires submitted to consumers followed by the monitoring of some detailed parameters using transducers specifically fitted on the tractor. This procedure is time-consuming and not totally reliable due to the trustworthiness in the questionnaire compilation. In all the high power tractors numerous transducers are fitted to monitor some parameters to optimise the operation of the machine. All of these transducers are connected to an electronic central unit or with the tractor CAN-Bus. In this context, a system able to monitor the operation and use parameters of the machine capitalising the existing transducers could represent the optimal solution for monitoring a high number of tractors, distributed in different regions. The high number of signals are in any case difficult to be memorised without a high quantity of memory. The goal of the paper is to define a methodology to memorise the operation parameters useful to define the mission profile of a tractor using a small memory. A tractor of a nominal power of 170 kW was selected and a system able to measure the signals acquired by the transducers fitted on the tractor was connected to the CAN Bus of the tractor. To reduce the memory requested to store the signals, all the signals were converted on matrices, with a similarly procedure used in the analysis of the strain gauge signals. In this way it is possible to count the number of occurrences for each event as the number of hours of tractor use, the number of hours for each gear use, etc. After a detailed analysis of the parameters measured on the tractor, the useful parameters were defined and acquired during 1000 hours of tractor use in different working conditions. The method defined in the paper has allowed to store the defined time of about 1000 hours into 100 kB, instead of 24 GB required to memorise all the parameters acquired by the transducers. The analysis of the parameters stored in the memory has allowed a detailed analysis of the operational parameters of the tractor in different applications. These parameters could be used by the engineers to design tractors with a higher quality and reliability and also to define predictive maintenance criteria and reduce the unexpected tractor failures. |
