# Design and Analysis of a Chinese Medicine Based Humanoid Robotic Arm Massage System
## 6 Simulations and Experiments  
### Statistical Analysis of the Humanoid Robotic Arm Massage System  
The ANSYS software is a general finite element analysis software. To verify whether the design of the robot arm strength and stiffness meet the design requirements, the humanoid massage robot arm was built via CATIA 3D model with the data interface built into the ANSYS [29; 30]. A stress diagram and displacement nephogram can be obtained, which evaluates the strength and stiffness of the parts and components of the whole arm structure optimization, and achieves miniaturization, weight reduction, and anthropomorphism of the massage robot arm.  
A humanoid massage robot arm has a series structure, where the arm shell, the rotating shaft, and the bearing may be deformed. The rigidity of the arm indicates the end-effector, which can overcome the deformation force under the external force. The strength and stiffness of the humanoid massage robot arm are the main factors which affect the dynamic characteristics and position accuracy under loaded conditions. Therefore, it is a key step in designing a humanoid massage robot arm. The size of the external load directly determines the size of the terminal deformation, which affects the positioning accuracy of the terminal. In a certain range of terminal variation, the static stiffness can be controlled by the terminal output force.  
During the movement of the humanoid massage robot arm, there will be a state of maximum force and deformation, that is, the arms of the robot are in a straight line. At this time, the gravity arm reaches the maximum value, so each arm of the humanoid massage robot arm is subject to the maximum state of force. In this paper, the state of maximum force and deformation were selected and investigated for static analysis. Both the upper and lower arms were fixed at one end, and the other end applied a reaction force and bending moment when the constraints were added in the design of the humanoid massage robot arm. Thereby, we could obtain the deformation and stress of each component in the most dangerous and deformed state. Owing to the load type and the structural characteristics and analysis requirements of the built entity, the size of the mesh division should be less than or equal to the minimum wall thickness of the entity. Finally, we adopted a free meshing method for the body of the humanoid massage robot arm. The following were the specific mesh divisions: the boom bracket was divided into 8223 units and 37,357 nodes; the shoulder pitch bracket was divided into 5127 units and 21,767 nodes; the number of units obtained by the elbow pitch bracket was 4772, and the number of nodes was 18,155. The elbow rotation bracket was divided into 4462 units and 15,076 nodes.  
The finite element analysis of the key components of the shoulder joint and the elbow joint was completed by adding a load, and the torque was applied by establishing a node at the center of the component, which obtained a highly accurate simulation result. The stress and deformation cloud diagrams of the shoulder and elbow joint structures are shown in Figures 13 and 14.  
The stress and deformation diagrams show that the structural design was unreasonable and facilitated the determination of corresponding improvements. The key components on the arm of the humanoid massage robot were analyzed in the actual analysis through the ANSYS software. The design of each part ensured rigidity to minimize weight. Therefore, the designed arm was also optimized by using dynamics and finite element analysis. The small deformation area of the arm was improved, resulting in a small, lightweight, and anthropomorphic arm.