A truly universal system to optimize consumptions, monitor operation and predict maintenance interventions for internal combustion engines must be independent of onboard systems, if present. One of the least invasive methods of detecting engine performance involves the measurement of the exhaust gas temperature (EGT), which can be related to the instant torque through thermodynamic relations. The practical implementation of such a system requires great care since its torque-predictive capabilities are strongly influenced by the position chosen for the temperature-detection point(s) along the exhaust line, specific for each engine, the type of installation for the thermocouples, and the thermal characteristics of the interposed materials. After performing some preliminary tests at the dynamometric brake on a compression-ignition engine for agricultural purposes equipped with three thermocouples at different points in the exhaust duct, a novel procedure was developed to: (1) tune a CFD-FVM-model of the exhaust pipe and determine many unknown thermodynamic parameters concerning the engine (including the real EGT at the exhaust valve outlet in some engine operative conditions), (2) use the CFD-FVM results to considerably increase the predictive capability of an indirect torque-detection strategy based on the EGT. The joint use of the CFD-FVM software, Response Surface Method, and specific optimization algorithms was fundamental to these aims and granted the experimenters a full mastery of systems’ non-linearity and a maximum relative error on the torque estimations of 2.9%.

Measuring the performance of the compression-ignition internal combustion engine of agricultural machines (in particular, the torque delivered instantaneously) is an essential requirement for monitoring: (a) the exploitation of the engine mechanical-energy potential (in terms of generated torque) and (b) its correct operation (in terms of global efficiency, fuel consumption and possible ageing). Due to the many important technical and economic implications, the instant acquisition of the engine torque is therefore a critical point in any operational monitoring system, as well as in predictive maintenance models. Torque measurement is by no means a simple task, especially in old agricultural machines lacking of default data acquisition devices/on-board electronics, and many critical issues arise from the fact that it involves rotating components (shafts), which are often difficult to be accessed. For this reason, an indirect torque measurement methodology, based on a predictive model relying on the exhaust gas temperature, is preferable. An accurate measurement of temperature data is of primary importance to precisely calculate the torque, which means performing an accurate thermocouple choice, placement, and data elaboration. This is made even more challenging by the fact that the temperature of the exhaust gas is often in a transient state due to variable engine regime necessary for machine operation. The study presented here illustrates some considerations about the trend and the equation of the experimental measurements of the exhaust gas temperature, considering three different positions for the thermocouples on the exhaust line, and proposes an optimal technical solution in terms of sensitivity and promptness of response.

MetroAgriFor intends to create an active and stimulating forum where academics, researchers and industry experts in the field of measurement and data processing techniques for Agriculture, Forestry and Food can meet and share new advances and research results. Attention is paid, but not limited to, new technologies for agriculture and forestry environment monitoring, food quality monitoring, metrology-assisted production in agriculture, forestry and food industries, sensors and associated signal conditioning for agriculture and forestry, calibration methods for electronic test and measurement for environmental and food applications.

The development of a test system to complete existing equipment in a research laboratory is a real design-activity, with even high complexity levels and many constraints, in terms of resistance to mechanical stresses and geometric connectivity to existing mechanical interfaces as well. Such a project must also be focussed, if possible, on cost saving and realisation speed, to make the best possible use of research funds, having often a limited time-availability. Concurrent Engineering (CE), born in the early 90s, is as a well-defined system approach to optimize the design and engineering cycles, with emphasis on tasks parallelization. In particular, CE revolves around the concept of considering all elements of a product lifecycle in the early design phases. By doing so, the resulting project is virtually free from design errors, which are expensive to be corrected in existing components and critical for the success of that project. The "Theory of Inventive Problem Solving" or TRIZ includes a practical methodology, some tools, a knowledge-base and a model-based technology for generating innovative solutions for problem solving. CE and TRIZ together can be particularly-effective also in the design of unique components, e.g. those composing the equipment of a research laboratory. This work illustrates the approach followed in defining a component of a system to measure the agricultural machinery performance. This rig will connect the rear wheels of a tractor to an existing PTO-dyno through two multiplication stages. In particular, the cited methodologies have been applied in the development of a hubadapter, i.e. the element that interfaces with the machine in test. The research for technical documentation and standards, the direct measurement of existing parts, the computer-aided design with 3D-modelling and finite element calculation of the components, have allowed to obtain iteratively a project verified in all aspects, ready to be realized.

The propulsion system of an agricultural machine is in charge for the delivery of the engine power to the soil and allows a vehicle travelling and performing its duties. Based on the type of this system, agricultural machines can be divided in tracked and wheeled. Although the former have their own specific applications and advantages, the latter are the most widely used. Over the time, different tyre typologies have been developed keeping into account many factors, such as tractor models, sizes and types of field/tillage operations, and wheel rims were changed accordingly. Notwithstanding an attempt of standardization by ISO, the design of these components is still conditioned by manufacturers' previous choices and there are some interchangeability issues. The knowledge of existing differences/dimensions is useful when there is the need for maintenance, substitution or connection of whatever device to a tractor axle. So, with the aim of developing a universal piece of experimental equipment to be used to detect the tractor performances (torque, power) at the wheels, i.e. a hub adapter, a systematic study of the different rim types has been performed. After having collected many data through direct measurements or interviews, all information has been elaborated using many statistical tools, such as scatter plots, frequency charts and clustering algorithms. Finally, four different classification keys have been applied to identify a minimum set of dimensional/functional classes of tractors using similar rims and, hence, capable of using the same hub adapters. The results of this study were then successfully used to design two optimized adapters. Their features (dimensions, number of holes) would let these two adapters connect the test equipment to the axle shafts of up to 1961 tractors of our database, corresponding to 81 % of the farm tractors below 100 kW on the Italian and European market, thus maximizing the cost-benefit ratio for these components.