**2. Methodology**

In this MR simulation, a computer with X-Plane software represented the simulation platform, and a real quadcopter within an airfield represented the real platform. In this paper, the interaction between the real and the virtual quadcopters in real time is called MR simulation. The data flow between the real and the virtual quadcopters are shown in Figure 1. More precisely, we developed a connection interface between the X-Plane flight simulator and the quadcopter ground control station (GCS) using the transmission control protocol/internet protocol (TCP/IP) [30] and the user datagram protocol (UDP) [31] in MATLAB. Both are the suite of communication protocols used for data transferring. For the simulation of the performance of the real quadcopter on the X-Plane platform, we needed the position (latitude, longitude, and altitude) and attitude (pitch, roll, and heading) data from the real quadcopter. The GCS receives the real-time flight data of the real quadcopter through a radio telemetry device. In our case, the developed connection interface needed two ways of communication; one to receive the real-time data from the GCS and the second to send the real-time position and attitude data from the received flight data to X-Plane. Therefore, here, we used, TCP/IP communication between the GCS and developed interface, and UDP communication between the developed interface and X-Plane. By using the developed connection interface, the GCS sends the real-time position and attitude data to X-Plane, and the virtual quadcopter in X-Plane follows the real quadcopter. Consequently, here, the virtual quadcopter interacted with the real quadcopter in real time (i.e., MR simulation).

**Figure 1.** Data flow between the real and the virtual quadcopters (overview of mixed reality simulation).
