## 3 Results and Discussions
To evaluate the effectiveness and usefulness of the R2R communication and multi-robot collision system for multi-robot systems, the developed communication system and the algorithm were tested in the field. It evaluated three different cases for validating the collision avoidance algorithm in the field experiment. Firstly, the case of the real distance and the calculated distance are equal, and the real  
Figure 11 shows the test result for collision avoidance in the case of the real distance and the calculated distance being equal and the real angle is greater than or equal to the calculated angle. Robot 1 has a passing priority due to its low robot number. Robot 1 moves with a heading angle of approximately 170 degrees. On the other hand, Robot 2 moves at an angle of about 50 degrees. When the robots reach the collision boundary, Robot 2 stops and Robot 1 moves forward. After Robot 1 is out of the collision boundary, Robot 2 resumes its movement. Figure 12 shows the test result for collision avoidance in the case of the positive of the calculated real tangent angle. Robot 1 moves with a heading angle of approximately 290 degrees. On the other hand, Robot 2 moves at an angle of about 110 degrees. When the robots reach the collision boundary, the robots stop, and Robot 2 starts the collision avoidance maneuver. Robot 2 turns 90 degrees right and moves forward as far as its width; Robot 1 continues to move forward. After Robot 1 moves out of the collision boundary, Robot 2 moves back by its width and turns 90 degrees to the left. Then, Robot 2 continues to move in its direction. Figure 13 shows the test result for collision avoidance in the case of the negative of the calculated real tangent angle. Robot 1 moves with a heading angle of approximately 130 degrees. On the other hand, Robot 2 moves at an angle of about 310 degrees. When the robots reach the collision boundary, the robots stop, and Robot 2 starts the collision avoidance maneuver. Robot 2 turns 90 degrees left and moves forward as far as its width; Robot 1 continues to move forward. After Robot 1 moves out of the collision boundary, Robot 2 moves back by its width and turns 90 degrees to the right. Then, Robot 2 continues to move in its direction. Several algorithms for multi-robot collision avoidance have been proposed over the last few decades. These are potential fields [32], the dynamic window [33] inevitable collision states [34], sequential convex programming [35], model predictive control [36], priority-based planning [37], social forces [38], buffered Voronoi cells [39], barrier certificates [40], reciprocal velocity obstacle (RVO) [41], optimal reciprocal collision-avoidance (ORCA) [42], reciprocal orientation algorithm (ROA) [43], and shortest distance algorithm (SDA) [44]. However, none of the algorithms have been supported by a robot-to-robot communication system. In this paper, a new algorithm is suggested to solve the problem of multi-robot collision avoidance. The main idea of the study is to define the transition priority for the robots and to start the maneuver for collision avoidance from the two encountering robots to the one that does not have the transition priority. In this way, it is ensured that the robots for agricultural applications continue their work without leaving the route they should follow. The basis of the developed algorithm is formed by the developed robot-to-robot communication system. When the studies in the literature are evaluated, it is seen that this  
Figure 13: Test result for case 3.  
study is important in terms of communication between ground-based mobile robots. In addition, the collision algorithm is unique in the software prioritization of robots.