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D.E.A. Propagation, Télécommunications et Télédétection

In order to better understand the complexities of modern tractor rollover, this paper investigates the energy absorbed by a Roll-Over Protective Structure (ROPS) cab during controlled lateral rollover testing carried out on a modern narrow-track tractor with a silent-block suspended ROPS cab. To investigate how different tractor set-ups may influence ROPS and energy partitioning, tests were conducted with two different wheel configurations, wide (equivalent to normal ‘open field’ operation) and narrow (equivalent to ‘orchard/vineyard’ operation), and refer to both the width of the tires and the corresponding track. Dynamic load cells and displacement transducers located at the ROPS-ground impact points provided a direct measurement of the energy absorbed by the ROPS cab frame. A trilateration method was developed and mounted onboard to measure load cell trajectory with respect to the cab floor in real-time. The associated video record of each rollover event provided further information and opportunity to explain the acquired data. The narrow tire configuration consistently subjected the ROPS cab frame to more energy than the wide tire arrangement. To better evaluate the influence of the ROPS cab silent-blocks in lateral rollover, static and dynamic tests were performed. The results confirm that tires influence the energy partition significantly and that further understanding of silent-blocks’ dynamic performance is warranted.

A tractor losing lateral stability starts to rollover. It is a matter of fact that tractor lateral rollover accidents are one of the most frequent causes of death and injuries for farmers. Consequently, tractors are fitted with a specific protective structure to minimize the consequences for the driver during the rollover (ROPS). The narrow-track tractor, designed to operate in vineyards and orchards, is a tractor category with a very narrow track width and the risk of rollover is higher. The aim of the study was to evaluate the compact narrow-track tractor types commercially available, designed to mount a cantilever engine in the forward position with effects on the Center of Gravity (CoG) because more than 50% of the tractor weight is loaded on the front axle, and, specifically, the articulated narrow-track tractors where the stability is affected by the pivot point connecting the two tractor bodies. As a consequence of the typical tractor design of articulated tractors, during the steering action the line passing through the front and rear tire contact points on the ground changes, influencing the tractor’s stability. The approach of the research was based on reproducing the lateral stability tractor condition by developing a kinematic model, with the goal to virtually simulate the tractor behavior and to calculate the lateral stability angle for articulated tractors. The innovative contribution of this paper was the tractor articulation joint modeling, assuming a virtual pivot point to reproduce two relatives’ rotations between the front and rear bodies of the tractor: vertical (yaw angle) and longitudinal (roll angle) rotations. The lowest value of the stability angle was 39.3°, measured at −35° yaw angle. The model at the tractor design stage will allow adjusting of the tractor parameters to improve the lateral stability performance.

Tractor rollover is one of the most hazardous event for the operator. Roll-Over Protective Structure (ROPS) was introduced to protect operator passively. In the specific case of protective structures in front of the drivers and fitted on wheeled narrow-track agricultural tractors, ROPS has to avoid the non–continuous rolling in the event of lateral rollover. Mathematical Model is included in the preliminary tests of the standardised testing procedures issued by the Organisation for Economic Co-operation and Development in order to check non-continuous rolling behaviour in narrow-track wheeled agricultural tractors. Modern narrow-track tractors fitted with rubber-tracks are currently designed but the standardised calculation does not cover the rubber-track tractors. The aim of the evaluation was to analyse the lateral tractor rollover behaviour as affected by the replacement of the tyres with the rubber-tracks. In the tested tractor the fitment of rubber-tracks replacing the rear wheels showed to increase the tractor mass and to affect the position of Centre of Gravity causing a downward and rearward shift with respect to the equivalent wheeled tractor. The track-ground interaction was different compared to the tyre-ground one. Mainly, the behaviour of the rubber-track with respect to the tyre at the state of unstable equilibrium under full load caused the rotation of the tractor around the outer edge of the track.

Vehicle rollover is a common event in agriculture due to the variability of the pedological and orographical condition of the soil and/or to human incorrect practices. Tractors since 1930 have been considered at risk of rollover and they were fitted with roll-over protective structures (ROPS) which had to provide a survival volume for the operator. The Directive 2006/42/EC currently foresees the same approach for the agricultural machines when a risk of rollover is recognised. The main purpose of the work was to identify a suitable survival volume for small multi-tasks agricultural vehicles. The study carried out evidenced that the design and operational characteristics of these small vehicles require an ad hoc survival volume. Indeed the official volumes already consolidated for tractors and other machines, even if in all cases consider the dimension of a seated male operator, had to be adapted in respect to the space actually provided by the features and operational characteristics of the small sized vehicles in order to preserve their functionality in the normal operation.

Le modalità di stoccaggio e confezionamento delle sementi orticole coinvolgono oltre agli aspetti economici, organizzativi e logistici altre tematiche di grande importanza quali la conservabilità e la germinabilità. Tali tematiche assumono particolare rilevanza in prodotti generalmente di elevato valore commerciale quali le sementi orticole. Nonostante i progressi ottenuti negli ultimi anni nelle ricerche sulle modalità di stoccaggio e conservazione relative all’identificazione delle migliori condizioni di germinabilità, permangono irrisolte le problematiche nel campo dell'automazione del confezionamento. Tra queste le tipologie dell’involucro, le sue caratteristiche in relazione alle interazioni con agenti esterni ed interni nonché aspetti più generali quali la logistica. Nel quadro appena tracciato, con il presente studio si è inteso valutare l’influenza dei materiali di confezionamento sulla conservabilità di sementi di differenti specie. Le prove, rientranti nell’ambito di un vasto programma di ricerca finanziato dalla Regione Emilia-Romagna, sono state effettuate presso una nota azienda sementiera della Romagna nel cui ambito è stato messo a punto un impianto automatico per il confezionamento. Al fine di ricavare informazioni specifiche sui materiali più idonei, sono state utilizzate quattro tipologie di involucro ritenute rispondenti alle esigenze della sperimentazione, messe a confronto con quello tradizionalmente utilizzato in ambito aziendale (raffia, carta con interno di nylon) e confezionato manualmente. Le prove sono state condotte su semi di ravanello, cipolla e lattuga. Al fine di verificare l’influenza delle condizioni di stoccaggio, i sacchi sono stati collocati in due ambienti differenti, una cella con temperatura e umidità costanti ed un magazzino tradizionale. I risultati della ricerca dimostrano che il confezionamento automatico non determina una significativa variabilità sulla germinabilità delle sementi che risulta invece dipendente dal tipo di involucro utilizzato ed in parte dalle modalità di stoccaggio.

Fatal injuries due to tractor rollover are a matter of concern all around the world. The role of the tractor in modern agriculture has changed and it seems necessary to verify the energy and the force requirements specified by the Standard tests for Rolling Over Protective Structures (ROPS). Real tractor overturn tests could provide a means for investigating the subject. This paper presents the work on the set-up of a modern narrow track tractor with the intention of real rollover testing. In particular, two different acquisition systems have been developed and installed on the tractor . The first, composed of load and displacement transducers, allows a direct measurement of the energy absorbed by the ROPS in a controlled rollover event. The second acquisition system, based on accelerometers and data acquisition unit, allows accelerometer readings in the time domain to be recorded. Data from this second system, linked to a video record of the overturning event, provides an alternative method for calculating the energy subjected to the ROPS. Tests performed in controlled cases are aimed at finalising a functional set-up of the tractor and ultimately permitting more realistic rollovers to be studied. Here focus is given to the project layout and instrumentation set-up of the tractor together with some preliminary results related to the testing of the first acquisition system.

L’interesse per la produzione di uva e le rinnovate pratiche di coltivazione della vite, anche in relazione alla riduzione della vita media degli impianti, ha incrementato in modo consistente le richiesta di barbatelle. Il complesso delle operazioni per la realizzazione di una talea, ed in particolare l’innesto della marza in un portainnesto e la successiva paraffinatura vengono effettuate da operatori specializzati, con il semplice ausilio di macchine ad azionamento manuale, con elevati rischi per l’operatore, ridotti tempi di lavoro e considerevoli spese di produzione. Nel contesto generale dell’evoluzione della meccanizzazione dei processi produttivi agricoli è sembrato utile, anche in tale comparto, raffigurare un percorso teso alla automatizzazione delle lavorazioni descritte. Sulla base di un’accurata analisi delle operazioni manuali effettuate all’interno di un’azienda specializzata nella produzione di barbatelle, è stato possibile progettare una stazione automatica d’innesto e paraffinatura che si ritiene compatibile con i costi di produzione attuali.