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“Choosing a wearable safety system: cost and performances”
 

ARIANNA, in the frame of the PROTECT project (co-funded by the European Commission), after the quantitative and qualitative output of the assessment of the requirements and constraints, analyses the cost-effectiveness of a localisation and tracking system in GPS-denied environment.

 

The study provides a sound confirmation that the major objective of the system scale-up toward a market-ready system is NOT the complete fulfilment of all the possible requirements coming from all the practitioners and stakeholders, but a system design capable of representing the better suited trade-off between the cost/performance of the system and the fulfilment of the requirements relevant to the major percentage of the risky situations.

 

The Figure 1 illustrates, in a indicative quantitative way, the different “market” impact of the two possible ways of fulfilling the requirements provided by the end-users.

  1. Blue plot: the system is designed to cope with the operational scenarios; this should be in line with the expectations of the practitioners, because their “ideal” target should be to have a performing system, independent of the specific intervention scenario.

  2. Orange plot: the system is designed to cope with the scenarios associated with the most risky situations, which are a subset of all the possible scenarios; this should be in line with the cost-effectiveness of the system, pursued by the customers, because such a system is actually needed if and where a risky situation can jeopardise the operations and can provide a boost of the situational awareness, if and where needed, but not when is not needed.

 

On one hand, a design capable of coping with all the possible scenarios would have a cost very rapidly increasing with the percentage of the fulfilled scenarios; for instance, as far as the operators walk, the relevant scenarios can be fulfilled by a 0.5 k€ system, but the cost would rise to 10 k€, if we want a system also performing when the operator swims or skates. It is apparent that, above a certain threshold, there is no market for the system, because it will exceed the purchase capabilities of the customers.

 

The Figure 2 shows the weighted risk level associated with the typical movements performed during the operations; from that analysis, the Table 1 has been elaborated, showing that the movements already managed by ARIANNA (indicated as green lines in the table) can already face 83.6% of all the “risk normalised” movements; in addition, with the ongoing system improvements, can handle an additional 10.6% (use of ropes and platform lifts), achieving the capability of handling the 94.2% of the risky cases.

 

The above evaluation is in line with the achievement of a system performing in the highest possible percentage of the risky scenarios, meanwhile keeping the system cost below the expenditure capabilities of the customers.

Figure 1: Illustrative example of the system cost as a function of the percentage of fulfilment of a) the requirements relevant to the operational scenarios and b) the requirements relevant to the risk factor associated with the scenarios (for instance, 97% of all the possible scenarios (no matter their risk factor) can be covered with a 50 k€ system, but 97% of the risky scenarios can be covered with a 1k€ system).

Figure 2: weighted risk level associated with the typical movements performed during the operations

Table 1: walking style and the associated percentage of the weighted risk level