The Artificial Bee Colony (ABC) algorithm is a swarm intelligence-based optimization algorithm inspired by the foraging behavior of honey bees. In this lesson, we will study Introduction to Artificial Bee Colony (ABC) algorithm. Karaboga in 2005 proposed this intelligent search algorithm for the first time. The ABC algorithm simulates the search for food sources by honey bees in a colony. The ABC algorithm employs a population of artificial bees that explore the search space to find the optimal solution to a given problem. The algorithm consists of three types of bees: employed bees, onlooker bees, and scout bees. Each bee performs a specific role in the search process. The inspiration for the ABC algorithm comes from studying the intricate behavior of these simple-looking entities. Let’s dive a little deeper into understanding the underlying mechanism that makes Bees a much smarter worker. But before moving any further, if you want to jump into the implementation of the ABC algorithm. Check out Python and MATLAB codes here. (Python Code for the ABC algorithm, MATLAB Code for the ABC algorithm)
Within a bee swarm, numerous intelligent behavioral patterns can be observed, including task delegation, mating, navigation, nest site selection, and foraging. Notably, the foraging activity of bees demonstrates remarkable efficiency through self-organization and division of labor. This division of labor is reflected in the categorization of foraging bees into three groups: employed bees, onlooker bees, and scout bees, each playing a specific role in the foraging task. The employed bees undertake the exploitation of food sources and recruit other bees through dancing. On the other hand, the onlooker bees remain in the hive, selecting a food source by observing the dances performed by the employed bees. Honey bees are well-known for their remarkable ability to communicate information about food sources to their fellow hive members through intricate dance patterns. These dances serve as a sophisticated means of conveying vital information such as the location, quality, and distance of food sources. There are primarily two types of dances used by honey bees: the round dance and the waggle dance.
- Round Dance: The round dance is a simple and repetitive dance performed by honey bees to communicate the presence of a nearby food source. This dance pattern is used when the food source is located within a short distance from the hive, typically within a radius of 50 meters. The round dance conveys the presence of a food source and stimulates other bees to go out and search for it. The intensity of the dance and the strength of the shaking provides a rough indication of the food source’s quality. However, the round dance does not provide detailed information about the precise location or direction of the food source.
- Waggle Dance: The waggle dance is a more sophisticated and informative dance performed by honey bees to communicate the location, quality, and distance of food sources located at greater distances from the hive. It involves a combination of straight-line movements, waggling motions, and specific orientation angles. The dancing bee moves in a straight line on the surface of the comb, usually in a vertical or slightly inclined direction. The angle at which the bee performs the waggle run with respect to the vertical axis of the comb indicates the direction of the food source in relation to the position of the sun. While moving in a straight line, the dancing bee performs a waggling motion by rapidly shaking its abdomen from side to side. The duration and intensity of the waggle run provide information about the distance and quality of the food source. The duration of the waggle run is directly proportional to the distance of the food source. Bees can perceive and interpret the duration of the waggle run to estimate the distance they need to travel to reach the food source. By interpreting the waggle dance, other bees in the hive can gather precise information about the location, distance, and quality of the food source. They can adjust their foraging behavior based on the communicated information and efficiently navigate to the identified food source.
Division of labor in Honey Bees:
In a hive, bees are characterized as Employer Bees, Onlooker Bees, and Scout Bees based on the task assigned to them. These bees switch their roles accordingly depending on the environmental factors and requirements of the hive.
- Employed Bees: Employed bees are the worker bees actively engaged in the exploitation phase of foraging. They are responsible for finding and exploiting food sources. Each employed bee selects a specific food source and performs a local search around it. This local search involves exploring the neighborhood of the chosen food source by modifying its position or parameters. During their exploration, employed bees collect information about the quality of their chosen food source and the associated nectar amount. They evaluate the fitness of the food source based on some objective criteria specific to the problem being solved. If an employed bee discovers a better solution than its current food source, it updates the position or parameters of the food source accordingly. Moreover, employed bees play a crucial role in communicating the location and quality of the food sources to other bees in the hive. They share this information through the communication mechanism mentioned above. By performing specific dance patterns, employed bees convey the direction, distance, and quality of the food source to recruit onlooker bees for further exploration.
- Onlooker Bees: Onlooker bees are the bees that observe the dances performed by employed bees within the hive. They play a vital role in the exploration phase of foraging. Onlooker bees wait in the hive and monitor the dances of the employed bees, which provides information about the quality and location of the food sources. The onlooker bees select a food source to explore based on the information gathered from the employed bees’ dances. The probability of choosing a particular food source is often proportional to its fitness value. Higher fitness values indicate better-quality solutions. Once an onlooker bee selects a food source, it performs a local search around that particular solution. This local search involves exploring the neighborhood of the chosen food source and evaluating its fitness. Onlooker bees continuously update their selected food source if they find better solutions during their exploration.
- Scout Bees: Scout bees are responsible for the diversification of the search process in the foraging task. Their primary role is to explore new areas of the search space that have not been sufficiently explored by employed and onlooker bees. Scout bees are activated when employed and onlooker bees fail to improve a particular food source after a certain specific time period. By collectively utilizing the efforts of employed bees, onlooker bees, and scout bees, the bee swarm exhibits a division of labor and self-organization, resulting in an efficient and effective foraging process that optimizes the search for food sources.
Researchers working in the field of computational intelligence and evolutionary computing realized the potential of these behaviors in designing efficient algorithms based on the patterns observed in nature, like in the case of honey bees. These new computational paradigms open new avenues for handling artificial intelligence and machine learning problems. In the next lesson, we will understand the implementation details of the Artificial Bee Colony algorithm. If you want to read more about the ABC algorithm, check out the original article written by Karaboga himself. Enjoyed reading this, consider sharing with your friends and loved ones to support us. Happy Learning!