## 3 Results and Discussions  
This work is focused on the wireless R2R communication mechanism and the collision avoidance algorithm for multi-robot applications in precision farming. The development of modern information technologies and wireless communication technologies are very important to provide connectivity for portable and mobile precision farming applications. And the development of autonomous mobile robots is continuously gaining importance for repetitive agricultural tasks in the agricultural domain. One aspect often neglected during the development of autonomous mobile robots is the communication of the multiple robots working in the same agricultural field. In this paper, a wireless R2R communication system between mobile robots was proposed to solve this aspect. The experimental wireless network contains a mobile robot server and more than one mobile robot client. The proposed mobile robot server reads the spatio-temporal data, which are sent from all the mobile client robots. It stores all the data in an array, creates the WiFi message frame, and sends it to the mobile robot clients. Figure 10 shows an algorithm for collecting and merging the spatio-temporal data of the mobile robot clients with the help of developed software. Figure 9: A step-by-step schematic illustration of the collision avoidance system (**1**) Step 1 (**2**) Step 2 (**3**) Step 3 (**4**) Step 4 (**5**) Step 5 (**6**) Step 6. The Split() method, which is used to split a string based on the delimiters passed to the string, is part of the string class in C#. The Split() method returns an array of string (Unit[]) generated by splitting the original string separated by the \"-\" delimiter passed as a parameter in the Split() method. All data from mobile robot clients splits and moves to an array (Data[]) according to robot numbers. As soon as a message is received from any mobile robot client, the algorithm is run and the array containing the data of all mobile robot clients in the network is sent to the relevant mobile robot client. The maximum length of the data field in a Wi-Fi message frame is 2312 bytes. The spatio-temporal data were sent as 33 bytes of data in this study. This means that the wireless R2R communication system is capable of supporting a maximum of 70 mobile robots per wireless network. The number of supported mobile robots seems to be satisfactory for precision farming applications. In a developed wireless R2R communication system, every mobile robot is capable of working as a mobile robot server or a mobile robot client. Nowadays, with the increase in the number of mobile robots in farming applications, communication and coordination between robots are necessary to fulfill complex agricultural tasks. Communication plays an important role in the performance of multi-robot systems, where the robots interact with each other to exchange their spatio-temporal data and collected sensor data. In the developed wireless R2R communication system, the Wi-Fi message frame contains 33 bytes of spatio-temporal data (UtmX, UtmY, Speed, and Heading) of the mobile robots. On the other hand, this system is also capable of sending other sensor data within the remaining 2279 bytes in the data section of the Wi-Fi message frame. Figure 10: Algorithm for collecting and merging the WiFi message frame. The multi-robots in farm areas need to adjust their locations in real time. For this reason, the data exchange of communication among multiple robots is mainly focused on wireless communication technology. This technology mainly involves a wireless local or personal area network such as Wi-Fi, Bluetooth, ZigBee, and IRDA (infrared data association). Among them, Wi-Fi technology has been mostly preferred in agricultural multi-robots [31]. When these three wireless communication technologies are compared, Wi-Fi technology has been used in our study due to its features such as fast transmission speed, long effective distance, reliable connection, and wide coverage.