Identifying the smartness of a mechatronic coiler through the System Engineering

Transcription

1 CONFERENZA INCOSE ITALIA SU SYSTEMS ENGINEERING CIISE 2014 Roma, Novembre 2014 Identifying the smartness of a mechatronic coiler through the System Engineering Eugenio Brusa, Ambra Calà Dept. Mechanical & Aerospace Engineering Politecnico di Torino, Italy 1

2 Model Based Systems Engineering and Design of heavy machines and industrial equipments Design of large equipments and heavy machines usually involves a fairly high level of complexity because of : the number of operations performed to complete the process the presence of several subsystems and components the need of a continuous monitoring and control the high demand of safety, reliability and performance the size of the system the number of coupling effects present (mechanical, thermal, electromagnetic ) Designers are currently prone to resort to two main approaches: Mechatronics to apply some artificial intelligence or smartness Systems Engineering to face and mastering complexity

3 The real contents of smartness? Very often defining some suitable smart function to be applied to the system is rather difficult although we know from the literature several attributes which might drive this activity (Skelton Bradley Meirovitch van Eyik ), but a straight application is sometimes hard Attribute Selectivity Self diagnosis Self tuning Sensitivity Shape ability Self recovery Simplicity Self repair Stability Standby skills Survivability Switch ability Description Capability of assessing the system properties depending on the working conditions Existence of intrinsic parameters which detect a failure condition Skill of performing an internal calibration Relation between cause and effect in the coupling (i.e. linear, nonlinear) Capability of modifying the system shape for different needs Possibility of reaching a saturation without failures Simplicity of the energy conversion mechanisms, of the configuration Skill of recover a stable and working condition after a saturation All the possible stabilities of the system operation Possibility of keeping a defined configuration Capability of avoiding failure modes Possibility of operating at different levels of energy if the architecture of the system allows

4 The role of the Systems Engineering The MBSE approach allows some main and powerful actions in this field: completing the system requirements by introducing some smart / adaptive / active function identifying and localizing the smart functions by allocating those additional requirements allows performing a trade off of architectures, electromechanical coupling phenomena detecting some physical hidden actor (present in physical material system never in sofware engineering) but often origin of some misunderstanding in design. through two challenging issues of the SE application: drawing the diagrams of the system model and inter-operating those with the physical models

5 An experience within Smart Steelmaking To clarify those issues a practical test case will be proposed concerning the shaping and storing of coils from steel rods outcoming from the rolling mill production line. System Super system Billets Rolling Finishing (coiling and delivery)

6 System : coiler unit The rolling mill The rod The system The storage The operator The monitoring and emergency system The powerline The building / environment Coiler is a sub-system of the whole plant and is located at the end of the product line. It needs to be carefully synchronized with the production line to avoid any accidental stop in delivery. It stops the rod within a certain distance from the cutting edge, it changes the shape from rod to a coil and it stores the coil. The quantum of motion associated to the rod translation (up to 150 m/min, i.e 2.5 m/s) is transformed into a rotational one. The rod is incoming into a rotating tubular shaft, connected to a so called laying head and it is delivered to the storage unit.

7 Customer s needs, feeling, dreams It is a matters of evidence that : The laying head and its bearings suffer a severe wear of material The rotor balancing is very critical because of the irregular distribution of rod mass within the head, especially at the beginning and at the end of each rod segment. Innovation motivates the manufacturer to: design a modular system, composed by a coiler system and a storage unit assure a precise synchronization of the rotor angular speed and the speed of the production line reduce wear by either changing or avoiding lubrication, but assuring the system safety against the risk of fire actively control any abrupt variation of the working condition (suggested active magnetic bearings with small gap and electromagnetic compatibility assured) submit this unit to the overall supervision of the main plant control system

8 SE : Smartness allocation through the diagrams [Use case] The question? USE CASE DIAGRAM ACCORDING TO THE CUSTOMER

9 V diagram DIMEC SE : Smartness allocation through the diagrams [Use case] Conflict? Power supply Maintains, tests and calibrates feeds Acquires data monitored and checks Imposes stops The powerline ( hidden actor in case of disfunction) Power seems to be fed without any query from the system but: -it has to be checked first and -eventually substituted by a back-up service Operator and Emergency system have simultaneously access to stop the system but -a hierarchy is required and -emergency system not only stops but also records the monitored signatures Additional remarks Requires suspension and rotation Requires shaping and delivery Provides grounding ( hidden actors in case of disfunction) only receives a sensor might measure the amount of rod processed The plant platform The platform is never asked to provide mechanical support or neutral potential reference (ground) in electric circuits, but in case of disfunction it applies some unsuitable action The storage unit usually only receives the rod but it could even measure the amount of rod processed, thus reducing the number of sensors applied to the rotor.

10 SE : Smartness allocation through the diagrams [States] Smart link The so called rotor nulling operation at standstill could be automatically performed by the system (by comparing currents and positions of the rotor shaft) and monitored by the supervision control system

11 SE : Smartness allocation through the diagrams [Activities] Sensors 1) Condition associated to the platform 1 status 2 3 2) Condition associated to the risk of fire 3) Condition associated to the safety Smart links - Need of sensors - Connection to the control systetm unit - Warning and monitoring

12 SE : Smartness allocation through the diagrams [Sequences] DIMEC Smart links - Landing of rotor has to be safe: back up in power feeding is required and automatyically activated upon warning about the lack of main power feeding - A direct measurement of coils stored by the storage unit can allow stopping the delivery from the laying head

13 SE : Suggestions related to the block diagrams Signature monitoring requires a defined resolution Canned rotor to avoid contact between rod and inductances Compatibility of electric connections with power line standards Switching amplifier to decrease dissipation Safe landing on additional bushings Reliability of mechanical connections against CIISE fatigue 2014 Rome, Italy E. Brusa, A. Calà Politecnico di Torino Detection of the real neutral phase

14 Requirements improvement Customer needs and preliminary requirements Requirement diagrams

15 Additional requirements, towards the smartness Examples SR007 : Wear (CN): The system shall reduce the wear of materials in operation. SR007-1 : Wear (TN): The system shall be suspended without direct contact SR : Wear (SN): Contactless suspension through active magnetic bearings shall control and stabilize the system dynamics in operation. SR012 : Safety against fire (CN): The system shall prevent any risk of fire. SR012-1 : Safety against fire (TN): The system shall use special lubricants to prevent any risk of fire. SR012-2 : Safety against fire (TN): The system shall prevent any abrupt dissipation which might induce a severe increasing of temperature. SR026 : Switch-ability (SN): The system shall be operated by resorting to different levels of power, i.e. by switching from one power set to another as in power amplifiers working in switching mode.

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17 Mechatronics vs. Systems Engineering: results

18 Testing, verification, validation Tests: - nulling - levitation at standstill - critical speed crossing - stable supercritical rotation - unbalance response when rod feeding - safe landing - rod stopping - storage saturation

19 Customer s satisfaction about the SE implementation Difficult synchronization Severe wear of bearings and material, run-outs, unbalancing Imperfect detection of processed rod The rolling mill The rod The system The storage The operator The monitoring and emergency system The powerline The building / environment Fire prevention Problems with lack of power Problems with mechanical and electric grounding

20 Conclusion DIMEC Application of the SE to the specific context of mechatronics for large industrial equipment still needs some assessment in terms of conventional interpretation of diagrams, functions, components. Requirements verification, refinement and assessment is greatly improved and somehow smartness contents are clarified and requirements better allocated. In the test case customer s satisfaction was reached. In terms of methodology for design a very good matching between the mechatronic approach and rules and the results of Systems Engineering was found. Challenging issues are : updating the standards in mechatronics by fruitfully using this approach vs assessing the tools of Systems Engineering for the mechatronics context.

21 Thank You for Your kind attention! prof. Eugenio Brusa, ing. Ambra Calà Politecnico di Torino Dept. Mechanical & Aerospace Engineering ; ambra.cala@polito.it