The Metal Press Case Study

In this report we present our experience with the tool-supported FMEA process using Behavior Trees as a modeling notation, the failure mode injection technique, and a model checker as analysis tool. The approach is based on the work in [3]. As a case study we use the industrial press [1], which is similar to the one described by [2, 3]. The report describes in detail how we derive the Behavior Tree model from the functional requirements. We provide a formalization of the safety requirements, describe the injected failure modes and present the results of the FMEA. We conclude the report with an analysis of the performance of the proposed process. 1 The Industrial Metal Press The industrial metal press is a system for compressing sheets of metal into body parts for vehicles. When the press is turned on, a plunger begins rising, with the aid of an electric motor. The operator may then load the metal into the press. When the plunger reaches the top of the press, the operator can then push and hold a button, which turns off the motor, causing the plunger to fall. For the safety of the operator, the button is located a safe distance away from the falling plunger. When the plunger reaches the bottom, thereby compressing the metal, the motor is automatically turned on. The plunger begins rising again, repeating the cycle. The operator may abort the fall of the plunger by releasing the button, but only if the plunger has not yet reached the ”point of no return” also referred to as PONR. It is dangerous to turn on the motor when the plunger is falling beyond this point, as the momentum of the plunger could cause the motor to explode, exposing the operator to flying parts. A software controller operates the motor based on inputs received from the system’s operator via the button, as well as three sensors for detecting the