I'm currently working on a Hiker model in Netlogo.
The hikers walk in a row and the first hiker is the slowest. Overtaking is not allowed. Is there a possibility to build in a function, with which the hikers, after reaching their foreman, take this new speed and stay behind him?
Sounds a like lot the Traffic models from NetLogo's Models Library. I'd suggest you take a look at Traffic Basic and Traffic 2 Lanes and try to adapt one of them to your problem.
The code from Traffic 2 Lanes is a bit more sophisticated, but might also be a more robust base to build on. (And it can be made to work for only one lane, thus preventing overtaking, by setting number-of-lanes to 1 in the code tab.)
Related
I need to measure the time forklift spends in collision, however movement_log
for agent type that is a forklift managed by transporter, fleet is not available. I also can not use statecharts because it uses much performance.
Situation: I am simulating a warehouse with one-way aisles and the capacity of these one-way aisles is 2 vehicles. There are situations
where a forklift (the yellow one) needs to wait behind another one in one-way aisle, I currently have that modeled properly I just don't know how to detect this situation and log it.
Thank you
I would do it as following:
Create a new 2-dimensional variable called collisionLog.
Check the speed [getSpeed() function] and state [TransporterState getState() function] every 1 second.
Write these into the collisionLog.
Once the simulation is completed, remove the rows with idle status.
Then do the calculations based on the fact that when speed is zero and transporter is busy, then you have the waiting vehicle.
There is no accessible trigger point (typically an action of a block) to trap when transporters have collisions. Yes, that situation obviously has to be captured internally to enable the transporters to avoid collisions, but in this situation that is not exposed as a block action, or action anywhere else. (AnyLogic space markup elements never have actions, except for some of the newer Material Handling library ones like Station, because these effectively represent a process step.)
The Transporter Control block has all the settings for collision detection and avoidance, but no related actions.
So your alternatives are really
'Scan' for this situation occurring: Yashar's answer, inferring that zero speed when non-idle means 'waiting due to collision' (which may or may not be 100% robust) being one way.
Explicitly break down the movement (from the process perspective) to define the potential 'conflicts' and decision-making within the process flow (e.g., if you're trying to move to an aisle, move to an entrance node, reserve a space in the aisle using resource pools or similar, and only enter when free). Clearly that doesn't cover every possible case, but may be useful in some situations.
The actions that do exist in the Transporter Control block could help a bit here (for both alternatives) since at least you have action points on entering paths and nodes. (You could also raise an enhancement request with AnyLogic to add collision-related actions here....)
I have a huge model with large number of forklifts, checking any attribute every second would result in huge performance loss
I also can not use statecharts because it uses much performance
Have you actually tried it though? Some things do not result in as much of a performance hit as you might think, and performance should not be an a priori 'that will be too slow' thing; ideally you have requirements for acceptable performance and you work round that. (There are always trade-offs between performance, functionality and maintainability.)
[You also don't say how you think using statecharts could have helped. Did you mean doing the 'scanning' approach via a statechart, say with cyclic entry/exit from a Scan state?]
Info: The question was updated with more explanation
I want to transport a agent (e.g. bananas) with a moving agent (e.g. truck) from place A to place B, where, for example, place A is where the bananas where plucked and place B is some storage for the bananas. So the bananas are simply being transported by the truck. Especially, the agent to be moved (the bananas) are not a resource (in the sense of Anylogic PLM) and have no upper amount limit.
There are various ways to solve this problem, but most of them either require some element in the model that I don't need or want (for example, a rack/pallet system in the case of the block 'Rack Store') or require the agents to be Anylogic resources.
As described in this answer, it kinda makes sense to use pickup and dropoff for this task. The problem is that the agent to be moved is not being transported, so that answer does not solve my question. To explain further, when the agent to be moved (the bananas) are being dropped off at the target location (place B), they simply re-appear at their original location (place A), even though the truck which picked them up via the pickup block has moved to place B.
I made a minimal example of this here.
As I described, the 'transportation' only works if I add the separate 'moveTo1' block for the dropped off agents.
Is there any simple and obvious way to handle this rather simple task of transportation in Anylogic without having multiple move blocks or other workarounds? I know there is 'ResourceAttach', but that requires the agent to be moved to be resources, and there is 'RackStore', which requires a rack/pallet system, which I don't need or want in my model.
What I want to know is what the 'standard' Anylogic way would be to do this.
Thanks a lot in advance!
Now I understand what your problem is...
When you use dropoff, the block that comes after it needs to define the new location of the agents, otherwise they stay in the same place.. You can use the moveTo block with a jump so the agents are teleported to the location you want them to be:
In almost all the blocks of the PML you can define the agent location in the properties, and this is a case where using that property is necessary.
You can set the position of the bananas to the position of the truck.
e.g. using agent.setXY(container.getX(), container.getY()) in the "On dropoff" field.
It seems to work for a simple test model.
Say, I have System1 that connect to System 2 through the adapter-microservice between them.
System1 -> rest-calls --> Adapter (converts request-response + some extra logic, like validation) -> System2
System1 is more like a monolith, exists for many countries (but it may change).
Question is: From the perspective of MicroService architecture and deployment, should the Adapter be one per country. Say Adapter-Uk, Adappter-AU, etc. Or it should be just the Adapter that could handle many countries at the same time?
I mean:
To have a single system/adapter-service :
Advantage: is having one code-base in or place, the adaptive code-logic between countries in 90 % are the same. Easy to introduce new changes.
Disadvantage: once we deploy the system, and there is a bug, it could affect many countries at the same time. Not safe.
To have a separate system:
Disadvantage: once some generic change has been introduced to one system, then it should be "copy-pasted" for all other countries/services. Repetitive, not smart.. work, from developer point of view.
Advantage:
Safer to change/deploy.
Q: what is a preferable way from the point of view of microservice architecture?
I would suggest the following:
the adapter covers all countries in order to maintain single codebase and improve code reusability
unit and/or integration tests to cope with the bugs
spawn multiple identical instances of the adapter with load balancer in front
Since Prabhat Mishra asked in the comment.
After two years.. (took some time to understand what I have asked.)
Back then, for me was quite critical to have a resilient system, i.e. if I change a code in one adapter I did not want all my countries to go down (it is SAP enterprise system, millions clients). I wanted only once country to go down (still million clients, but fewer millions :)).
So, for this case: i would create many adapters one per country, BUT, I would use some code-generated common solution to create them, like common jar - so I would would not repeat my infrastructure or communication layers. Like scaffolding thing.
country-adapter new "country-1"
add some country specific code (not changing any generated one (less code to repeat, less to support))
Otherwise, if you feel safe (like code reviewing your change, making sure you do not change other countries code), then 1 adapter is Ok.
Another solution, is to start with 1 adapter, and split to more if it is critical (feeling not safe about the potential damage / cost if fails).
In general, seems, all boils down to the same problem, which is: WHEN to split "monolith" to pieces. The answer is always: when it causes problems to be as big as it is. But, if you know your system well, you know in advance that WHEN is now (or not).
I read about how FoundationDB does its network testing/simulation here: http://www.slideshare.net/FoundationDB/deterministic-simulation-testing
I would like to implement something very similar, but cannot figure out how they actually did implement it. How would one go about writing, for example, a C++ class that does what they do. Is it possible to do the kind of simulation they do without doing any code generation (as they presumeably do)?
Also: How can a simulation be repeated, if it contains random events?? Each time the simulation would require to choose a new random value and thus be not the same run as the one before. Maybe I am missing something here...hope somebody can shed a bit of light on the matter.
You can find a little bit more detail in the talk that went along with those slides here: https://www.youtube.com/watch?v=4fFDFbi3toc
As for the determinism question, you're right that a simulation cannot be repeated exactly unless all possible sources of randomness and other non-determinism are carefully controlled. To that end:
(1) Generate all random numbers from a PRNG that you seed with a known value.
(2) Avoid any sort of branching or conditionals based on facts about the world which you don't control (e.g. the time of day, the load on the machine, etc.), or if you can't help that, then pseudo-randomly simulate those things too.
(3) Ensure that whatever mechanism you pick for concurrency has a mode in which it can guarantee a deterministic execution order.
Since it's easy to mess all those things up, you'll also want to have a way of checking whether determinism has been violated.
All of this is covered in greater detail in the talk that I linked above.
In the sims I've built the biggest issue with repeatability ends up being proper seed management (as per the previous answer). You want your simulations to give different results only when you supply a different seed to your random number generators than before.
After that the biggest issue I've seen seems tends to be making sure you don't iterate over collections with nondeterministic ordering. For instance, in Java, you'd use a LinkedHashMap instead of a HashMap.
The user in this webinar;
http://www.mathworks.com.au/videos/parameterizing-bodies-68850.html?form_seq=conf1134
can create new levels of links for the scissor lift by copy pasting the sub systems.
I was wondering if there was any way the number of subsystems and the joints could be automated via user input.
i.e a gui which allows the user to input the number of levels in the scissor lift and that number of levels (subsystems) is generated in SimMechanics.
If someone could provide a solution I could adapt it to the problem I'm trying to solve.
Thanks in advance!
Yes, you can automate it, as long as you know what susbsytems and what joints you want to add. The functions of interest are:
add_block(path_to_your_subsystem,path_to_destination_subsystem) (I assume your susbsystem is stored in a library). You probably want to specify the 'Position` parameter so that all blocks don't end up on top of each other. It will take some experimenting to find coordinates that work for your model and that are parameterised based on the number of susbystems to add.
add_line(path_to_subsystem_of_interest,path_to_output_port,path_to_input_port). You'll need to know which port you want to connect to which and figure out how many times you need to do this based on the number of subsystems to add. Simscape and SimMechanics are a special type of ports, and you need to refer to them correctly otherwise it won't work, see Programatically connect two subsystems for more details (note: this is undocumented as far as I know and is therefore likely to change in a future release).
So in short, yes it's possible (I've done it in the past), but it's by no means easy. See this blog for a very simple introduction.