I am noticing some "strange" behaviour in the Road Traffic Library. In my model, I seize and release resources based on the position of a vehicle on the road network. The reason for this is not the issue here but in the model execution, some vehicles seemed to miss the seize step. To try and understand what was happening, I created a very simple model with a simple T-junction. Injecting a car on the vertical leg and moving it straight to the stopline at the intersection and specifying that it must stop before the line before proceeding to the next block which moves the vehicle on the horizontal, works as expected. However, if I put another stopline on the vertical road before the junction and add a carMoveTo block to first move the car to this stopline (but setting it to pass through) and then moving it to the stopline at the junction (set to stop before) the behaviour becomes inconsistent. The outer lane on a 2 lane road works as expected, but on the inner lane, the car overshoots the stopline at the junction and ends up in the intersection even before completing the block.
Can anyone explain why AnyLogic is doing this and how I can ensure that the car stop as specified?
EDIT
I have created a demonstration model in the public AnyLogic cloud at
Road Traffic Demo
Also see below screenshot for an illustration
Without the pass-through stopline the vehicle completes the block in column 2 at zero speed (stop at intersection). With the mass-through the vehicle complete the block in column 2 (carMoveTo1) at speed ~30kph (does not stop at the intersection) - I update the value of the variable "speed" on exit from the relevant block in column 2 using the car.getSpeed(KPH) method.
It seems my question was poorly formulated and what I thought was a self-explanatory example wasn't. However, I think Benjamin actually answered it in his first comment. It seems AnyLogic calculates the vehicle physics one block at a time thus it allows the car to accelerate up to its preferred speed at the pass-through StopLine and then only in the next block determines that it needs to stop at the next line and therefore needs to decelerate. If the pass-through line is too close to the stop line then the car cannot decelerate fast enough and "overshoots" the stop line. I have tested this in the example model by moving the pass-through line further away from the stop line and when far enough away, the car stops as expected with or without the pass-through block.
Related
I'm building a pedestrian model using Anylogic. I have set my agents move in several groups between S2/S3/S4 and S1 (the movement direction is indicated by the blue two-way arrow in the figure).
Background picture for problem statement:
One group of my agents should have appeared from any position in S2(line) and moved toward S1(line), but in fact, I found several agents with obvious abnormal detour behaviour appeared. Their trajectories are shown as the red line with arrows. I have checked there was no interference of other agents at the same time.
May I ask what causes such a small amount of agents to produce this abnormal behaviour since I have set the same behaviour for the whole group? And how to fix this behaviour?
I am modeling a warehouse yard where trucks arrive, get loaded/offloaded and leave the site. The complexity arises when modeling the drop trailers. Those vehicles consist of two parts: tractor and trailer. Tractor and trailer enter the yard as one entity and move to the parking lot. There, the tractor drops the trailer (turquoise colored rectangles in the picture below) and then then leaves the yard. After some time another tractor (pink colored in the picture below) comes to pick up one of those trailers. When there is no free space in the parking lot, model throws an error, because I use carMoveTo block to send it to the parkingLot. Therefore it requires additional space to move the tractor. How can I avoid this issue? In fact, I do not want that pink tractor to seize a free parking lot, but to pick up one of those trailers. I tried suppressing the error by using "on the way not found" option in the carMoveTo block, but I need to get a close-to-reality animation of the yard.
I would not advise mixing the road traffic library blocks with the Process Modelling Library (PML) Blocks, unless you really need to.
You can get near-perfect animation by making use of a network-type model and just the PML blocks. You will start by replacing your Car Move To block with just a MoveTo block
You can check the WholeSale Warehouse example in AnyLogic.
There they make use of a network diagram and PML blocks to simulation all the relative parking movements of trucks and trailers.
You can do something similar by creating the correct network and node points that indicate how a truck must move when it is parking a trailer and when it is picking up a trailer.
If this solution is not scalable and you cant draw lines, you can always simply just specify the X,Y, Z coordinates.
You might then need multiple MoveTo blocks for the entire movement or you can create some sort of loop where you give a truck a list of locations to move to, the truck will go through the loop and simply execute moving to the next location in the list, until it is done and then continue with the flow chart
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 am developing (or atleast trying to develop)
a decently big real time tactics game (something similar to RTS) using SpriteKit.
I am using GamePlay kit for pathfinding.
Initially I used SKActions to move the sprites within the Path but fast enough I realized that it was a big mistake.
Then I tried to implement it with GKAgents (this is my current state)
I feel that GKAgents are very raw and premature also they are following some strange Newton Law #1 that makes them to move forever (I can't think of any scenario where it would be useful - maybe for presentations at WWDC)
as well as I see that they have some Angular speed to perform rotations
which I don't need at all and can't really find how to disable it...
As well as GKBehaviors given a GKGoals seems to make some weird thing...
Setting behavior to avoid obstacles makes my units to joggle around them...
Setting behavior with follow path goal completely ignores everything unless the maxPredictionTime is low enough...
I am not even willing to tell what happens when I combine both them.
I feel broken...
I feel like I have 2 options now:
1) to struggle more with those agents and trying to make them behave as I wish
2) To roll all the movement on my own with help by GKObstacleGraph and a path Finding (which is buggy as well I have to say at some points the path to the point will generate the most awful path like "go touch that obstacle then reverse touch that one then go to the actual point (which from the beginning could be achieved by a straight line)").
Question is:
What would be the best out of those options ?
One of the best ways (in SpriteKit/GameplayKit) to get the kind of behavior you're after is to recognize that path planning and path following need not be the same operation. GameplayKit provides tools for both — GKObstacleGraph is good for planning and GKAgent is good for following a planned path — and they work best when you combine the strengths of each.
(It can be a bit misleading that GKAgent provides obstacle avoidance; don't think of this in the same way as finding a route around obstacles, more like reacting to sudden obstacles in your way.)
To put it another way, GKObstacleGraph and GKAgent are like the difference between navigating with a map and safely driving a car. The former is where you decide to take CA-85 and US-101 instead of I-280. (And maybe reevaluate your decision once in awhile — say, to pick a different set of roads around a traffic jam.) The latter is where you, continuously moment-to-moment, change lanes, avoid potholes, pass slower vehicles, slow down for heavy traffic, etc.
In Apple's DemoBots sample code, they break this out into two steps:
Use GKObstacleGraph to do high level path planning. That is, when the bad guys are "here" and the hero is "way over there", and there are some walls in between, select a series of waypoints that roughly approximates a route from here to there.
Use GKAgent behaviors to make the character roughly follow that path while also reacting to other factors (like making the bad guys not step on each other and giving them vaguely realistic movement curves instead of simply following the lines between waypoints).
You can find most of the relevant stuff behind this in TaskBotBehavior.swift in that sample code — start from addGoalsToFollowPath and look at both the places that gets called and the calls it makes.
As for the "moving forever" and "angular speed" issues...
The agent simulation is a weird mix of a motivation analogy (i.e. the agent does what's needed to move it toward where it "wants" within constraints) and a physics system (i.e. those movements are modeled like forces/impulses). If you take away an agent's goals, it doesn't know that it needs to stop — instead, you need to give it a goal of stopping. (That is, a movement speed goal of zero.) There might be a better model than what Apple's chosen here — file bugs if you have suggestions for design improvements.
Angular speed is trickier. The notion of agents' intrinsic physical constraints being sort of analogous to, say, vehicles on land or boats at sea is pretty well baked into the system. It can't really handle things like space fighters that have to reorient to vector their thrust, or walking creatures that can just as happily walk sideways or backwards as forward — at least, not on its own. You can get some mileage toward changing the "feel" of agent movement with the maxAcceleration property, but you're limited by the fact that said property covers both linear and angular acceleration.
Remember, though, that the interface between what the agent system "wants" and what "actually happens" in your game world is under your control. The easiest way to implement GKAgentDelegate is to just sync the velocity and position properties of the agent and the sprite that it represents. However, you don't have to do it that way — you could calculate a different force/impulse and apply it to your sprite.
I can't comment yet so I post as an answer. I faced the same problem recently: agent wiggling around the target or the agent that keeps moving even if you remove the behavior. Then I realized that the behavior is just the algorithm controling the movement, but you can still access and set the agent's speed, position and angle by hand.
In my case, I have a critter entity that chases for food in the scene. When it makes contact with the food agent, the food entity is removed. I tried many things to make the critter stop after eating the food (it would keep going in a straight line). And all I had to do was to set its speed to 0. That is because the behavior will influence not the position directly, but the speed/angle combination instead (from what I understand). When there is no goal for the entity, it doesn't "want" to change it's state, so whatever speed and direction it reached, it will keep. It will simply not update/change it. So unless you create a goal to make it want to stop, it will wiggle/keep going. The easy way is to set the behavior to nil and set the speed to 0 yourself.
If the behavior/goal system doesn't do it for the type of animation you are looking for, you can still use the Agent system and customize the movement with the AgenDelegate protocol and the update method and make it interact with other agents later on. You can even synchronize the agent with a node that is moved with the physics engine or with actions (or any other way).
I think the agent system is nice to keep around since you can use it later, even if it's only for special effects. But just as mixing actions and physics can give some weird results, mixing goal/behaviors and any other "automated" tool will probably result in an erratic behavior.
You can also use the agent system for other stuff than moving an actual sprite around. For example, you could use an agent to act as a "target seeker" to simulate reaction time for your enemies. The agent moves around the scene and finds other agents, when it makes contact with a suitable target, the enemy entity would attack it (random idea).
It's not a "one size fits all" solution, but it's a very nice tool to have.
I'm trying to re-create a 'falling sand' simulation, similar to those various web toys that are out there doing the same thing - and I'm failing pretty hard. I'm not really sure where to begin. I'm trying to use cellular automata to model the behavior of the sand particles, but I'm having trouble figuring out how to make the direction in which I update the 'world' not matter...
For example, one of the particle types I'd like to have is Plant. When Plant comes in contact with Water, Plant turns that Water particle into another Plant particle. The problem here though is that if I'm updating the game world from top to bottom and left to right, then a Plant particle placed in the middle of a sea of Water particles will immediately cause all of the Water particles to the right and below that new Plant particle to turn into Plants. This is not the behavior I am expecting. =(
One straightforward solution is to not do each iteration in-place. Instead, every time you update the world, create a copy of it... then look at the original, but update the copy. That way the order of updating does not matter any more, because you are completely disregarding your updates while you're looking for particles.
Don't program it in a sequential way (looping over all particles) but use real simulation programming techniques in which every particle is treated as an individual object/agent that obeys the laws of physics and that can act (run) asynchronously and respond to "events" (interactions with other particles).
If making every sand particle a separate object is too fine-grained, then divide the world into small blocks of let's say 1000 particles and simlute the behavior of these blocks instead.