An In-Pit Crushing and Conveying (IPCC) system is a series-connected and continuously operating system. Therefore, every single equipment failure or delay will affect the utilisation of the throughput of the entire system (Foley, 2011). Moreover, the system downtime, including scheduled and unscheduled downtime, has negative impact on the system availability (Spriggs, Engineer, C M and Director, 2005). Effective system utilisation represents the productive hours used by the IPCC system during a period of time. The effective utilisation rate of a typical IPCC system is around 63 per cent, equivalent to 5500 effective working hours per annum. One of the significant system utilisation losses is the positioning and relocation of equipment, accounting for around 10 per cent of calendar hours. According to Harcus IPCC Time Utilisation Modelling (TUM) diagram, automated shovel/hopper locating has the potential to reduce this loss to 4 per cent due to equipment repositioning (Harcus, 2011). Tejchman and Hegde (1986) indicate that the IPCC system’s productivity and efficiency are limited by the achievable effective operating time of the single machine as well as their required moving or relocation time. McAree (2013) states that:
automation is not only a technology that can reduce the cost of production, but can enhance mining precision in terms of the optimised excavation sequence, guiding the machine’s motions with precision at maximum mining capacity, creating a fully coordinated mining system with integrating of individual smart machines.
At the user requirements stage of designing a complex automated relocation system for the IPCC system, Use Case Modelling (UMC) is a fundamental analysis tool. The UCM approach is commonly applied to develop complex software that can be effectively applied to help define function and performance requirements (FPR) for automation projects involving complex system interactions. This paper demonstrates examples of applying UCM to analyse bench excavation strategies for hopper/shovel interactions in a fully autonomous mobile in-pit crushing and conveying system. The paper also introduces the use of the Enterprise Architect (EA) program to document all Use cases systematically and generate sequence diagrams, test cases, and activity with action diagrams.