PSI - Issue 12

Francesco Mocera et al. / Procedia Structural Integrity 12 (2018) 213–223 Author name / Structural Integrity Procedia 00 (2018) 000–000

217

5

Fig. 4: Working cycle of an industrial telescopic handler

Evaluating the working cycle of a working machine is crucial in the design stage of a new architecture, allowing the identification of the critical phases and how they are distributed within the daily routine. Looking at a vertical feed mixer as the one addressed on this study, four main activities can be identified: • Drive: the machine has the ability to move itself to reach the stock blocks dislocated around the farm. • Silage loading with the milling head: the hydraulic milling head may be used to load silage previously compatted to fit the stock area. • Cutting and mixing: all the loaded ingredients have to be properly cut and mixed to obtain the best meal prop erties for the livestock. Several knives placed on the tank wall and on the augers edges automatically cut the silage during its mixing motion up to the desired length. • Silage unload: once the meal has reached the desired characteristics, the farmer can unload it on the appropriate slots for the livestock. The working cycle the feed mixer has to accomplish is a proper combination of these basic activities. Apart from slight di ff erences between each user, these machines are characterized by a high degree of repetitiveness of the working cycle.

4. Experimental study: performance analysis

To design a new architecture for a well established machine it is important to have a clear picture of all the tasks it will have to accomplish. The best way is to observe how the users use the traditional machines in their daily activities. In this way, critical aspects can also be pointed out and taken into account in the design of the new machine. In the following sections, the acquisition tools and methods and the main results of the experimental campaign are shown.

4.1. Tools and methods

To characterize the working cycle of the machine it is important to observe some major quantities during the daily activities. In this way, it is possible to understand what the user asked to the machine and how it behaved depending the specific activity it was doing. In this work, these quantities have been monitored reading the engine feedback on the CAN BUS network of the machine. The CAN ( Controller Area Network ) is a communication protocol designed by Robert Bosch Gmbh in the early ’80s (Voss, 2005). The structure of this protocol allows to have several control modules connected to the same bus, being able to communicate with each other with only a twisted pair of cables. In the NRMM field on top of the lower CAN BUS layer, a higher level communication standard is adopted. The most common is the SAE J1939 (Voss, 2008). It consists of