# Development of a Virtual Reality-Based System for Simulating Welding Processes
## 2 Materials and Methods  
### Architecture of the Virtual Reality-Based System  
Figure 1 shows the architecture of the virtual reality-based system for simulating welding processes. The system enables to simulate three welding processes, including SMAW, MIG, and TIG, in connecting with the physical system. By a change in the physical system, such as moving the welding torch or the distance between the welding torch and welded plates, there will be a change in weld formation in the virtual reality environment. In consideration of the engineering requirements of the VR system, components, and architecture of the VR system, including software and hardware and how to build a VR system [9; 28; 29; 30], we proposed a VR-based system including four modules as follows:  
1. Module #1 was responsible for controlling the infrared radiation source and controlling the stepper motor to shorten the welding rod. Module #1 included microcontroller unit #1 (MCU#1), infrared emitter, and stepper motor. MCU#1 received the control signals from computer to activate the infrared emitter and stepper motor and sent feedback signals to computer. So, the connection between MCU#1 with computer was two-way connection via recommended standard 485 (RS485) port, which is a communication standard defining the electrical characteristics of drivers and receivers for use in serial communication systems [31]. MCU#1 used the 5 volts of direct current (5V-DC) power source. To emit the infrared signals for the SMAW, MIG, and TIG welding process, the infrared emitters were attached on the welding torches for each welding process. Stepper motor was used to describe the truncation of the welding filler rod in the case of the TIG welding or the electrode wire or weld stick in the case of the MIG and SMAW welding processes. For emitting the infrared signals, the 850 nm light-emitting diode (LED) infrared light was utilized. 2. Module #2 was responsible for receiving and sending the infrared radiation source to the VR module. Module #2 included microcontroller unit #2 (MCU#2) and two circuit boards. In this module, there were two circuit boards that were considered as the two welding plates. Each circuit plate was attached to 32 infrared radiation (IR) sensors, which were radiation-sensitive optoelectronic components with a spectral sensitivity in the infrared wavelength range of 780 nm \(\div\) 50 \(\mu\)m [32]. These sensors were responsible for receiving the infrared source from the IR emitter attached on the welding torch. MCU#1 received the analog signals from the IR sensors and processed these signals to data as the current position of the welding torch, the distance from the welding torch to the plates, and the welding energy. Then, MCU#2 sent these data to the computer for describing the weld bead. So, the connection between the MCU#2 with the computer was one-way connection via RS485 port. To perform their functions, MCU#2 used the 5V-DC power source, while two circuit boards used the 8V-DC power source. 3. Module #3 was the VR-based simulation, which was responsible for simulating three welding processes (SMAW, MIG, and TIG). To simulate the virtual reality environment, the real 3D models for describing the welding processes, such as SMAW, MIG, and TIG, were scanned using the 3D scanner. Then, these point cloud models were converted to the 3D solid models using CAD software--Catia V5 R21. To develop the VR environment, the generation of the 3D models played an important role [33; 34]. Figure 1: Architecture of the virtual reality-based system for simulating welding processes. The filler rod appeared when simulating the TIG welding process. With the MIG and SMAW welding processes, the electrode wire or the weld stick appeared, respectively. The scenes showing the welding environments, such as in the factory and in the laboratory, were also added to the virtual reality environment. These models were inputted to the virtual reality simulation using the Unity3D platform.