## 4 Simulation Analysis of the Rehabilitation Robot Based on Virtual Prototype
### Dynamic Simulation Analysis  
In this paper, the dynamic analysis uses the three-dimensional model established in Section 2 into Adams (Automatic dynamic analysis of mechanical systems) software, and then set the parameters of the imported model, and add driving to each joint of the wearable upper limb rehabilitation robot. In order to select the motor and ensure the output torque to satisfy the needs of rehabilitation, the dynamic simulation of the wearable upper limb rehabilitation robot was carried out. Considering the differences between patients with joint bearing capacity, for most people to bear upon initial value, limb resistance to wearable upper limb rehabilitation robot is set to: 100 N in the horizontal movement direction, 200 N in the vertical direction, the end points are in the hand close to the elbow, shoulder rotation direction of 4 Nm torque, stress points in the forearm center of mass. The initial position of the simulation is the wearable upper limb rehabilitation robot arm extending horizontally to the front, and the simulation results are shown in Figure 11. The solid line in the diagram represents the torque, while the dotted line indicates the rotation angle of the robot. Figure 10: End angular velocity/angular acceleration curve. As shown in Figure 11, the dotted line is the joint rotation angle change curve, the variable is set to \(\theta\), the solid line is the joint torque change curve \(T\), and the variable is set to \(T=G\cdot L(\theta(t))\). From the torque formula \(L\), where is the distance from the center of mass of the robot arm to the axis of the shoulder joint. \[ \begin{array}{ll}i-1T_{i}&=A_{i}=\text{Rot}(Z,\theta_{i})\times\text{Trans}(0,0,d_{i})\times\text{Trans}(a_{i},0,0)\times\text{Rot}(X,a_{i})\\ &=\left[\begin{array}{cccc}\text{c}\theta_{i}&-\text{s}\theta_{i}\text{c} \alpha_{i}&\text{s}\theta_{i}\text{s}\alpha_{i}&a_{i}\text{c}\theta_{i}\\ \text{s}\theta_{i}&\text{c}\theta_{i}\alpha_{i}&-\text{c}\theta_{i}\text{s} \alpha_{i}&a_{i}\text{s}\theta_{i}\\ 0&\text{s}\alpha_{i}&\text{c}\alpha_{i}&d_{i}\\ 0&0&0&1\end{array}\right]\end{array} \]  
\({}^{i-1}T_{i}\) is a transformation matrix between adjacent arm joints based on the D-H parameter model. \[L=\sum\left[T\_i\left[\theta(t)\right]\right]\]  
The maximum angle is \(\theta=120^{\circ}\) in the initial position, and returns to the original position \(\theta=-280^{\circ}\), and then goes to the maximum angle \(\theta=120^{\circ}\). More specifically, Figure 11a shows the relationship between the rotation angle and the output torque of the drive motor when the shoulder joint moves in the vertical direction at different moments. As can be seen from the Figure 11a, when the arm abducts to the maximum angle, the torque required is larger, and the mechanism is furthest from the static balance position. Figure 11b shows the relationship between the angle of rotation and the torque on the worm gear when the shoulder moves horizontally. The wearable upper limb rehabilitation robot first swings up to the lowest point, then returns to the initial point, and finally swings down to the maximum angle. The maximum torque of movement in the horizontal direction occurs near the position from the top swing to the highest point, where  
Figure 11: Torques and angles of joints. (**a**) The rotation angle and the output torque of the drive motor when the shoulder joint moves in the vertical direction at different moments; (**b**) the relationship between the angle of rotation and the torque on the worm gear when the shoulder moves horizontally; (**c**) the relationship between the rotation angle of the shoulder joint and the output torque of the motor; (**d**) relationship between elbow flexion and extension angle and driving torque. the required continuous torque time is relatively large, indicating that the motor continues to work. Figure 11c shows the relationship between the rotation angle of the shoulder joint and the output torque of the motor. The forearm rotates 600 in, 600 out and back to the starting position.