## 2 Materials and Methods
### Experimental Design and Introduction
#### 2.1.4 Hardware and Software Introduction  
In this study, the mechanical and electrical system architecture of the robotic arm uses a PC and a real-time monitoring system as the control side. The host side is the Windows operating system, and the programming of the real-time monitoring system side is communicated by LabVIEW software and the embedded controller myRIO. The control process is that the host gives the control command to each rotary axis of the robotic arm, with a real-time monitoring system and embedded controller to control the corresponding pneumatic valve of each axis, through the rotary encoder and pressure sensor feedback information, in order to perform the task of tracking.  
The pneumatic artificial muscle cylinder is a tensioner produced by Festo (Esslingen, Germany, MAS-40-XXXXN-AA-MC-O-ER-BG), which uses pneumatic pressure as a power source to imitate the stretching motion of human muscles. Its structure is composed of a contraction system and two connectors, in which the contraction system is a flexible tube on the inside and a high-strength fiber mesh on the outside. When the internal gas pressure is applied, the flexible tube expands and deforms due to the high pressure, while the flexible tube squeezes the external fiber mesh to make its tensile displacement deformation, and the deformation is the expansion of the radial direction and the axial compression, and the axial compression is up to 25% of the original length of the pneumatic artificial muscle cylinder.  
The proportional directional control valve operates by converting the voltage input signal into a flow and flow direction control signal, and controlling the opening area as well as the inlet and outlet direction through the input voltage to achieve the purpose of controlling the pneumatic element. In this study, the proportional directional control valve (MPYE-5-M5-010-B) developed by Festo was used. The proportional pressure control valve operates by converting the voltage input signal into a pressure signal, and the proportional relationship between the input voltage and the output pressure is used to control the pneumatic element. The proportional pressure regulator (Model No. VPPM-6L-L-1-G18-0L10H-V1N) developed by Festo is used in this study with a pressure range of 0-10 Bar; input voltage range: 0-10 V; and return voltage range: 0-10 V. The pressure sensor is produced by Festo (SPAB-P10R-G18-NB-K1). By inputting a pressurized gas to its inlet, the sensor will automatically measure and display the corresponding pressure level. The pressure measurement range is 0-10 Bar, and the returned voltage signal is 1-5 V.  
The software part of the robotic arm designed in this study is developed by the LabVIEW program, including the kinematics and controller program. The control program is implemented on the NI myRIO embedded control platform, and the main purpose of the host PC is to execute the human-machine interface program through the user's command to the embedded control platform. Its embedded architecture can be divided into a Real-Time and FPGA side. The main function of the Real-Time side is to calculate the robot arm path planning and track the tracking controller design, while the main function of the FPGA side is to map software variables and the hardware IO position and encoder decoding work.