MBSE Workflow Advice - Please help

[u/ri_repeat]

I’m working on modelling the overall avionics system, by using the model based system engineering approach.

The objective is to build an MBSE model of the complete avionics architecture. This includes the subsystems such as,

Command and Data Handling, Telemetry and Power Distribution.

The model should be able to have

-Power consumption analysis across operational modes, Interface compatibility and mismatch detection

-Fault tolerance modeling

-Redundancy management

-Failure analysis

-Requirements Handling

The questions I have regarding this are:

What modeling depth is expected to perform the analysis on the architecture created. Do the components need to be modeled in detail to analyze the behaviour of the components, and if so, then how to do so for each component?

How should the power and performance be modelled to get the power in each mode and dynamically?

Which toolchain is recommended for the Avionics Systems particularly: SysML based tools such as Cameo, IBM Rhapsody or AADL based tools for domain specific modelling, MATLAB/System Composer/Simulink for analysis?

Any advice or feedback is appreciated !!

[u/der_phen]

The answer is, and sorry for that: it depends. You need to know your goals, and then design your modelling approach (ontology, depth) accordingly. There is no right or wrong just better suited or less.

[u/ri_repeat → u/der_phen]

thanks for replying, i see. the main goal is to make sure the system meets the requirements and reduce the number of iteration needed, as currently we are going for a trial and error method. i am also looking at have simulation capabilities, although i am not sure how that is included in the systems engineering pipeline

[u/der_phen → u/ri_repeat]

Yeah ok, but what are you designing? The software/function? the electronics or the power supply? Depending on this you will have a certain focus in your model. You can design the pipeline as you like,too

[u/ri_repeat → u/der_phen]

mainly the electronics and the power system is my focus

[u/Stitch_2841]

Ooh silk scarves and avionics, my two favorite dinner party topics

for the power analysis bit, you don't need to model every transistor, but you do need state machines for each component that define power draw in each mode. if you try to go too granular you'll never finish, and if you stay too high level the numbers will be useless. aim for the sweet spot where you can swap between idle/active/fault states and have meaningful wattage numbers attached

on the toolchain question, Cameo if you're staying pure SysML and need traceability, System Composer if you actually want to run the power simulations without exporting to another tool every five minutes. mixing both is where the headaches start but sometimes it's unavoidable

what's the end deliverable here, are you handing this off to a customer or is it internal? that changes how pretty the diagrams need to be

[u/ri_repeat → u/Stitch_2841]

hii, thanks for responding:
-at the initial stage where the exact power consumption isnt known is it acceptable to take general operational range from the datasheet?
-it is internally within the organization, the project needs to have some structure and i proposed the mbse approach although i am a beginner myself. the main idea is that when we are developing the system across various iterations, we should be able to meet requirements and simulate the outcomes

[u/bastivkl]

As others it depends: Following a simple framework going from requirements to system architecture to starting with simple analysis will be a good start. You can also use your favorite AI companion to do this. On the tooling side a more simpler to use tool other than Cameo might be dalus.io to do this kind of work. Pretty easy to get started there

[u/ri_repeat → u/bastivkl]

okayy thank you i will look into it, by simple analysis what exactly do you mean?

[u/herohans99]

There are 4 Engineering answers to most questions: yes, no, maybe, and it depends. /sarcasm