## 6 Individuation of Competing Factors
### Formulation of the Competing Factors Based on the Gathered Information  
In light of the considerations that emerged after analyzing the industrial domain through the literature and patents, it was possible to formulate the main competing factors that characterize and  
Figure 4: Search, screening, and selection results of the process to individuate relevant patents in the field of harvesting machines for shell fruits. differentiate existing solutions. In compliance with the indications provided in Section 2, along with the objectives of introducing value curves, the considered competing factors have to be non-redundant and defined in a positive way, i.e., the higher the corresponding level, the better. Specifically, to avoid overlapping competing factors, a process leading to the identification of independent benefits was performed. The individuation of the main (and distinct) functionalities of harvesting machines has benefitted this process, as shown in Figure 5. Here, extracted competing factors are shown in light blue boxes. In addition, one can infer that some competing factors relate to non-functional characteristics of the machines; more details follow. To perform the function of gathering, the machines have to first reach the shell fruits and, then, remove them from the ground. In order to reach the shell fruits, it is necessary that the machine is easily transportable, because before reaching the fruits, the machine should reach (or be moved to) the orchard from where it is usually stored. Therefore, a first competing factor is the _transportability_. To reach the shell fruits in all the spots in which they have fallen on the ground, the machine has to be maneuverable to avoid obstacles like stones and trees. Then, a competing factor is the _maneoverability_, in terms of the simplicity to perform movements for gathering shell fruits. Moreover, since many orchards are in mountainous areas, it is often useful that these machines are able to harvest on steep slopes. As a consequence, the machines' _suitability for working on slopes_ is considered a competing factor. As partially discussed in Section 4, mechanical/portable machines require just an operator. An energy resource, such as fuel or electricity, can be required by vacuum/portable machines and self-propelled architectures to operate. With regard to trailed/mounted architectures, a farm tractor is required in addition to the energy resource. Therefore, the _capability of a machine to be independent by external sources_ can be considered a competing factor. The machines' _productivity_, in terms of the mass of shell fruits collected per hour per operator, is a competing factor. In addition, a recurring theme in both the literature and patents is the inability of vacuum machines to be productive in the presence of moisture. Thereby, the machine's _capability of working correctly in presence of moisture_ can be considered an additional competing factor. The collection of clean material is desirable because it can both avoid the need to purchase additional sieving machinery and save time in the subsequent processing of the harvested fruits. Therefore, the _capability of separating foreign materials_, in terms of the capability to obtain the shell fruits without the presence of foreign materials, is another competing factor. The greater the capacity of a machine to contain the harvested fruits, the fewer interruptions will be required to empty it, and the higher the overall working efficiency of this field operation. Then, the _storing capacity_ is a competing factor. With regard to the restoring operation, no explicit useful function has emerged as a competitive factor. However, a benefit that can be enjoyed in this phase is the attenuation of a function harmful for  
Figure 5: Competing factors and their classification. the operator ascribable to vacuum machines, i.e., the creation of dust in the environment.