I built up a shopfloor where material flow is realized by Transporters (AGV / AMR) with free space navigation. I am looking for a possibility to observe traffic at certain spots (e.g. work stations, storage areas) or even on the whole shopfloor so I can compare different scenarios of the material flow and supply strategy of the working station with a view on the traffic. I tried out the Density Map but since it observes the whole layout which is quite big the values get too low for the scale quite fast so it isn't performing the way I want it to. Is there a way so set up like a "area density map" so I can just observe a defined rectangle or another functionality which could help me here?
Happy about all ideas! :-)
You can use normal Rectangular Node elements and trigger "on enter" code to count drive-throughs or similar, as below.
Just make sure to set the capacity to infinity so normal traffic flow is not interrupted :)
Related
In my model I've a path-guided transporter fleet, but when they are close to eachother they are blocking eachother, since this is not the scope of my model (I want them just to override eachother ) is there a way to disable this option. I've already tried to set minimum distance to obstacle very low or use very small dimensions (see figure) but everything seems not to work.
The key aspect of Material-Handling transporters is to apply that spatial blocking.
If you do not want it, use moving resources from the Process modelling library. They act the same but do not have spatial awareness. However, they also cannot do the free-space navigation. Path-guided works but not applying path-specific constraints.
So it is a trade-off. The process-library resources also require much less computational power...
i have a fork-lifter who takes the item from the truck and stock it in the rectangular node.
The problem is that i want that the fork-lifter stock the agent according to the attractors. Instead, the operator goes in the same point every time. Why?(i did the same with another flowchart and same blocks and there is no problem, maybe a network problem?).
YOu have to manually tell it to which attractor it should go. Attractors are not actual physical spaces (that become "full" if something is stored there). They are just spaces to separate things visually.
In your process blocks, you probably did not specify the attractors correctly or did not define to move to a random attractor. But even in the latter case, you could have things being stored in the same attractor.
Two options:
Either, turn your attractors into actual agents with rectangular nodes, that you setup to be "empty/full" with state charts (faster but harder to design)
Or use the material handling library with its storage system setup, doing this for your (but this is computationally slower)
I want to use 'process modelling library' to mimic vessel movement from one point to another (because 'road traffic library' cannot realistically reflect the ship movement).
However, I am stuck at defining a way for speed control and keeping a safe distance between two vessels. What I want to achieve is the speed of each vessel (agent) should be restricted in a threshold [MaxSpeed,MinSpeed], and all the vessels should keep a safe distance/time with the vessels in front or behind. For example, if a vessel with speed 15 knots catches the vessel with speed 10 knots, it will change the speed to 10 knots before reaching the required safe distance/time.
Currently, what I am thinking is to set the agent speed at 'Source' block or 'MoveTo' block, and create a function to avoid collision. Does anybody know how the function will look like? I am very appreciate if any idea or comments, thanks!
Even though depending on your model there may be smart ways of doing this, I will show you a generic inefficient way of doing this in a very simplified way without deceleration or any fancy stuff.
It's a good idea to first set up a node in front of your boat as a safety distance:
I also added an event that will check if other boats are getting too close to the boat itself... so in the event you can have code like this that runs every minute for example:
for(Boat c : main.boats){
if(unsafeDistance.contains(c.getX()-getX(),c.getY()-getY())){
setSpeed(c.getSpeed());
break;
}
}
This code checks if there is any boat inside the safety node, and if there is one, the boat will instantaneously change its speed to the speed of the boat in front of it.
This code is ugly and inefficient, but if you want something better, you need to think about it yourself using the characteristics of your situation in order to make it better... but this solution should work using moveTo blocks from the Process modeling library.
I want to ask about jelly physics ( http://www.youtube.com/watch?v=I74rJFB_W1k ), where I can find some good place to start making things like that ? I want to make simulation of cars crash and I want use this jelly physics, but I can't find a lot about them. I don't want use existing physics engine, I want write my own :)
Something like what you see in the video you linked to could be accomplished with a mass-spring system. However, as you vary the number of masses and springs, keeping your spring constants the same, you will get wildly varying results. In short, mass-spring systems are not good approximations of a continuum of matter.
Typically, these sorts of animations are created using what is called the Finite Element Method (FEM). The FEM does converge to a continuum, which is nice. And although it does require a bit more know-how than a mass-spring system, it really isn't too bad. The basic idea, derived from the study of continuum mechanics, can be put this way:
Break the volume of your object up into many small pieces (elements), usually tetrahedra. Let's call the entire collection of these elements the mesh. You'll actually want to make two copies of this mesh. Label one the "rest" mesh, and the other the "world" mesh. I'll tell you why next.
For each tetrahedron in your world mesh, measure how deformed it is relative to its corresponding rest tetrahedron. The measure of how deformed it is is called "strain". This is typically accomplished by first measuring what is known as the deformation gradient (often denoted F). There are several good papers that describe how to do this. Once you have F, one very typical way to define the strain (e) is:
e = 1/2(F^T * F) - I. This is known as Green's strain. It is invariant to rotations, which makes it very convenient.
Using the properties of the material you are trying to simulate (gelatin, rubber, steel, etc.), and using the strain you measured in the step above, derive the "stress" of each tetrahdron.
For each tetrahedron, visit each node (vertex, corner, point (these all mean the same thing)) and average the area-weighted normal vectors (in the rest shape) of the three triangular faces that share that node. Multiply the tetrahedron's stress by that averaged vector, and there's the elastic force acting on that node due to the stress of that tetrahedron. Of course, each node could potentially belong to multiple tetrahedra, so you'll want to be able to sum up these forces.
Integrate! There are easy ways to do this, and hard ways. Either way, you'll want to loop over every node in your world mesh and divide its forces by its mass to determine its acceleration. The easy way to proceed from here is to:
Multiply its acceleration by some small time value dt. This gives you a change in velocity, dv.
Add dv to the node's current velocity to get a new total velocity.
Multiply that velocity by dt to get a change in position, dx.
Add dx to the node's current position to get a new position.
This approach is known as explicit forward Euler integration. You will have to use very small values of dt to get it to work without blowing up, but it is so easy to implement that it works well as a starting point.
Repeat steps 2 through 5 for as long as you want.
I've left out a lot of details and fancy extras, but hopefully you can infer a lot of what I've left out. Here is a link to some instructions I used the first time I did this. The webpage contains some useful pseudocode, as well as links to some relevant material.
http://sealab.cs.utah.edu/Courses/CS6967-F08/Project-2/
The following link is also very useful:
http://sealab.cs.utah.edu/Courses/CS6967-F08/FE-notes.pdf
This is a really fun topic, and I wish you the best of luck! If you get stuck, just drop me a comment.
That rolling jelly cube video was made with Blender, which uses the Bullet physics engine for soft body simulation. The bullet documentation in general is very sparse and for soft body dynamics almost nonexistent. You're best bet would be to read the source code.
Then write your own version ;)
Here is a page with some pretty good tutorials on it. The one you are looking for is probably in the (inverse) Kinematics and Mass & Spring Models sections.
Hint: A jelly can be seen as a 3 dimensional cloth ;-)
Also, try having a look at the search results for spring pressure soft body model - they might get you going in the right direction :-)
See this guy's page Maciej Matyka, topic of soft body
Unfortunately 2d only but might be something to start with is JellyPhysics and JellyCar
I have an application in which users interact with each-other. I want to visualize these interactions so that I can determine whether clusters of users exist (within which interactions are more frequent).
I've assigned a 2D point to each user (where each coordinate is between 0 and 1). My idea is that two users' points move closer together when they interact, an "attractive force", and I just repeatedly go through my interaction logs over and over again.
Of course, I need a "repulsive force" that will push users apart too, otherwise they will all just collapse into a single point.
First I tried monitoring the lowest and highest of each of the XY coordinates, and normalizing their positions, but this didn't work, a few users with a small number of interactions stayed at the edges, and the rest all collapsed into the middle.
Does anyone know what equations I should use to move the points, both for the "attractive" force between users when they interact, and a "repulsive" force to stop them all collapsing into a single point?
Edit: In response to a question, I should point out that I'm dealing with about 1 million users, and about 10 million interactions between users. If anyone can recommend a tool that could do this for me, I'm all ears :-)
In the past, when I've tried this kind of thing, I've used a spring model to pull linked nodes together, something like: dx = -k*(x-l). dx is the change in the position, x is the current position, l is the desired separation, and k is the spring coefficient that you tweak until you get a nice balance between spring strength and stability, it'll be less than 0.1. Having l > 0 ensures that everything doesn't end up in the middle.
In addition to that, a general "repulsive" force between all nodes will spread them out, something like: dx = k / x^2. This will be larger the closer two nodes are, tweak k to get a reasonable effect.
I can recommend some possibilities: first, try log-scaling the interactions or running them through a sigmoidal function to squash the range. This will give you a smoother visual distribution of spacing.
Independent of this scaling issue: look at some of the rendering strategies in graphviz, particularly the programs "neato" and "fdp". From the man page:
neato draws undirected graphs using ``spring'' models (see Kamada and
Kawai, Information Processing Letters 31:1, April 1989). Input files
must be formatted in the dot attributed graph language. By default,
the output of neato is the input graph with layout coordinates
appended.
fdp draws undirected graphs using a ``spring'' model. It relies on a
force-directed approach in the spirit of Fruchterman and Reingold (cf.
Software-Practice & Experience 21(11), 1991, pp. 1129-1164).
Finally, consider one of the scaling strategies, an attractive force, and some sort of drag coefficient instead of a repulsive force. Actually moving things closer and then possibly farther later on may just get you cyclic behavior.
Consider a model in which everything will collapse eventually, but slowly. Then just run until some condition is met (a node crosses the center of the layout region or some such).
Drag or momentum can just be encoded as a basic resistance to motion and amount to throttling the movements; it can be applied differentially (things can move slower based on how far they've gone, where they are in space, how many other nodes are close, etc.).
Hope this helps.
The spring model is the traditional way to do this: make an attractive force between each node based on the interaction, and a repulsive force between all nodes based on the inverse square of their distance. Then solve, minimizing the energy. You may need some fairly high powered programming to get an efficient solution to this if you have more than a few nodes. Make sure the start positions are random, and run the program several times: a case like this almost always has several local energy minima in it, and you want to make sure you've got a good one.
Also, unless you have only a few nodes, I would do this in 3D. An extra dimension of freedom allows for better solutions, and you should be able to visualize clusters in 3D as well if not better than 2D.