## 1 Introduction
The main contributions of this paper are summarized as follows:  
(1) Owing to the anatomy theory, motion mechanism and range of human upper limbs, a novel wearable upper limb rehabilitation robot with tension mechanism is firstly designed, investigated and analyzed for upper limb injured patients based on flexible transmission during rehabilitation training process. A cable-driven modular parallel joints are innovatively designed for elbow/wrist and a shoulder joint driven by a toothed belt. All the cable-driven motors are rear-mounted to achieve long-distance transmission and reduce the drive inertia of the end joints. The gear belt is exploited to drive the joints of a wearable upper limb rehabilitation robot, which realizing high precision meshing. The design approach of the wearable upper limb rehabilitation robot facilitates the rehabilitation training of the joint, effectively reduces the volume, mass and inertia of the actuators, and achieves the lightweight design of the overall structure. (2) Additionally, this paper proposes a flexibly parallel mechanism of humanoid wrist driven by rope and supported through a compression spring. The fixed base and moving platform of the wearable upper limb rehabilitation robot are connected by three ropes and a conical compression spring. The springs are designed by simulating the human wrist and support the mobile platform to complete the wrist movement, while the ropes are constructed via simulating the wrist muscles to control the wearable upper limb rehabilitation robot. In this paper, the design approach will contribute to the further study of parallel mechanisms with flexible joints. The results will play an important role in reappearing the movement of human wrist and promote the development of rehabilitation robot and rope drive technology. (3) The kinematics and workspace of the wearable upper limb rehabilitation robot are verified and analyzed based on the D-H method and Monte Carlo method. It demonstrates that the wearable upper limb rehabilitation robot can satisfy the requirements of rehabilitation training through kinematics/dynamics analysis and rehabilitation training experiments. Therefore, it also further verifies that the feasibility and effectiveness of the design method, which provides a valuable idea for improving rehabilitation robot mechanism. The rest of this paper are organized as follows. From the perspective of bionics, Section 2 analyzes the joints of the wearable upper limb rehabilitation robot, and designs the mechanical system model of the joints. To obtain the relationship of rotation and translation between adjacent members of the wearable upper limb rehabilitation robot and its terminal pose, the kinematics model is investigated and analyzed for the wearable upper limb rehabilitation robot, and the correctness of the solutions is demonstrated for forward/inverse kinematics of the wearable upper limb rehabilitation robot in Section 3. Owing to the Monte Carlo method, the workspace and full workspace are analyzed and obtained for the wearable upper limb rehabilitation robot in Section 3. Section 4 simulates and analyzes the kinematics/dynamics model of the wearable upper limb rehabilitation robot to demonstrating the stability of the motion state and verifying the output torque of the motor can satisfy the needs of rehabilitation training process. In Section 5, the control system is designed for the wearable upper limb rehabilitation robot, and the rehabilitation training process is completed for upper limb injured patients, followed by the tracking result of the robot rehabilitation training. Conclusions are drawn in Section 6.