# Formation Control of Multiple Autonomous Mobile Robots Using Turkish Natural Language Processing
## 3 Autonomous Mobile Robots
### Multiple Mobile Robots  
Multi-robot systems are used for some tasks that a single robot cannot perform or which may be more costly. Instead of one powerful robot with a complex structure, multiple robots with more superficial structures can be used. Examples of multi-robot applications include exploration, search and rescue, and transportation [48; 49; 50]. There are two main ways in which multi-robot systems make decisions. These are centralized systems and distributed systems. In centralized systems, the movements of the entire robot group are managed by a single center. All information is collected in a central system or robot; the most appropriate decision is made there. In distributed systems, each robot makes its own decision. It can act independently of the other robots. Apart from these, market-based approaches have also been developed. In this approach, robots can perform a task on their own, or they can perform a given task as a robot community [51].  
Multiple robots need to be coordinated while performing a task. While forming the robot system, different classifications can be made according to the control strategy. Examples are behavioral, leader-follower, and virtual structure approaches [52]. Since the behavior-based control strategy integrates several goal-oriented behaviors simultaneously, multiple robots can simultaneously navigate to waypoints, avoid hazards, and maintain formation [53]. This control strategy allows robotic vehicles to concentrate and act on the inputs received by their sensors. Thus, all robots in the formation respond to the information they receive from their environment and ensure the formation is fully realized [54]. The virtual structure approach is used for the formation of structures that have the appearance of a fixed geometric shape. A general control strategy is developed to force a collection of robots to behave like particles embedded in a solid structure. In this approach, there is no need to select a specific leader for the formation [55]. Multi-robot systems using the leader-follower control method have at least one leader, with the rest of the agents acting as followers. The control design is such that the followers monitor the leader's position and follow the leader's prescribed trajectory. Two types of supervision are required here. One maintains the specified distance between the leader and the followers, and the other keeps the relative angle between them [56].  
The platoon formation is one of the most frequently used formation types in the literature [57]. In the platoon driving approach, the mobile robot system consists of more than one robot moving in a line like a single object. In this structure, each robot usually only receives information from the previous one [58]. The leader follows a set trajectory, and the followers must maintain a desired relative distance and orientation between them. Longitudinal controllers focus on keeping the relative distance between vehicles at a predetermined value [59]. Ref. [60] introduces a distributed guiding-vector-field (DGVF) algorithm for robots to form spontaneous-ordering platoons along a predefined path in an n-dimensional Euclidean space. In [60], the algorithm eliminates singular points and guides robots toward a self-intersecting path. Ref. [61] proposes a four-layer framework for cooperative mechanisms within and across strings and designs longitudinal and lateral controllers based on vehicle roles. Many approaches to this type of control have been proposed [57; 62; 63]. Another study used a platooning approach involving air and ground vehicles [64].  
This study preferred a distributed system according to the decision-making approach. The leader-follower approach was used as the control method. Detachment was used as the formation type.