Project for the class of Autonomous Agents and Multiagent Systems.
In the project, we implement a parameterisable simulation that allows us to observe how a struggling group of individuals manage their resources in order to survive against hunger and the attacks of oppressive beings. By using the Unity game engine, we are able to bring to life a world where these issues can be explored, and the data collected for further analysis.
By running simulations and observing our results, we are able to understand that while good coordination can completely eliminate a threat, it is difficult to guarantee the survival of every member of a group.
In this project we aim to represent a simulation of a mystical village (“The Shire”), where intelligent agents reside and interact with each other. These agents are divided in two factions: the human villagers and the evil orcs, who attack the villagers.
There is a component of resource-gathering within our simulation, which ties in with one of the most important elements of the environment: energy saving and replenishing.
We implemented a BDI architecture for villagers, and followed a simplified version of the Ortony, Clore and Collins model [1], where perceptions have an effect on an agent’s emotion intensity.
This simulation was implemented in Unity, with the scripting done in C#.
In this project our environment is:
- Inaccessible, the agent is only capable of knowing accurate information about things in front of it, not obscured by other objects, in a radius of 30m, with an angle of vision of 180º.
- Dynamic, as the environment updates as the agent is deliberating.
- Continuous, as any amount of actions or percepts can occur.
- Non-episodic, as all actions and perceptions influence the following ones, without being able to take a segment of actions independently from the previous ones.
The environment in question is a closed arena with resources, characterized by wells, a village, and obstacles such as rocks and trees.
The resources are scarcely placed around the map, at fixed, unknown points to the villagers. Spread across the map are also orcs wandering, which are hostile to the villagers.
The villagers have as goal to gather as many resources for the village as possible. The villagers also need to defend themselves from the orcs, which will try to attack them.
Villagers have health which they need to keep to avoid dying. When they are within the village, they regenerate their health slowly.
World events generate Perceptions, which the villagers process every 2 seconds. These Perceptions are used to generate an Action, which is how the villager interacts with the world. These Perceptions are passed to a Decider which can be dynamically decided before executing the program, with one of the given architectures.
We follow a traditional implementation of the BDI architecture, in which the perceptions generate beliefs, beliefs influence desires, desires are filtered into intentions, and intentions generate plans.
The agent can have beliefs about each agent in the map, about where it is, and what are its current characteristics in regards to health and resources. Beliefs also have a components of certainty, which, depending on the kind of belief it is, might be maintained or decreased with time.
For example, the belief that a resource point exists will always be certain, while the belief an orc is somewhere will decrease over time as the probability of it still being there after no longer knowing where it is decreases.
For the plan making, we followed a STRIPS architecture, using our filtered intention as the final goal of the plan.
The emotion architecture is based upon the BDI architecture, with the addition of an appraisal stage after getting the new Beliefs, to update the emotions.
Emotions follow a structure of valence and arousal, both mapped from -1 to 1. A negative valence is associated with negative emotions such as sadness and anger, and a positive valence is associated with positive emotions such as happiness. A negative arousal is associated with emotions with low intensity, such as depression and calmness, and a positive arousal is associated with emotions with high intensity, such as anger and joy. This follows the idea that affective experiences are best characterized by arousal and valence [2].
In our implementation we had plans to implement contagion using a base of the beliefs, in which the emotions of the other villagers would be informed to the character through perceptions, which it then would keep in beliefs, which would influence its emotions. Yet, we did not get the chance to implement this goal.