###### Abstract
Although they are lighter and less bulky, they have less joint torque and limited load capacity and cannot be used in an industrial setting. The Raytheon Company developed the XOS2 exoskeleton; the upper-limb portion has 5-DOF, including 3-DOF shoulders and 2-DOF elbows. The exoskeleton can perform lateral-lifting, raising-up, pull down and other actions. It can amplify user strength and endurance and allow them, for example, to lift 200-lb loads repeatedly without tiring [2; 3]. [PERSON] of the Scuola Superiore Sant'Anna in Italy developed a type of whole-body exoskeleton called the Body Extender system with a weight of 160-kg [4; 5; 6]. The upper-limb of the exoskeleton has 5-DOF (including a crawl DOF). It can amplify the power of the human body 3-20 times, and each arm can lift a 50-kg load. These power-assisted exoskeletons with anthropomorphic structures have large joint torque and heavy load capacity. However, due to their complex structure and heavy weight, they are not suitable for industrial applications. [PERSON] et al. [1] of the Hanyang University developed an upper-limb exoskeleton for material handling, which is called the Hanyang University EXoskeleton Assistive Robot (HEXAR). It has 3-DOF, including 2-DOF shoulders and 1-DOF elbow, and is actuated by motors. The exoskeleton is used to handling heavy loads in industrial settings by the front side of the operator body. When carrying loads in front of the body, HEXAR's assistive principle is the same as the XOS2 developed by Raytheon and the Body Extender system developed by Santa Ana University of Italy. They are all assisted by the anthropomorphic shoulder flexion/extension and elbow flexion/extension. The torque generated by a load on the elbow joint is entirely driven by the elbow flexion/extension actuator, which makes the elbow actuator larger and heavy, and the volume and weight of the upper-limb exoskeleton can hardly be reduced. Many of the existing power-assisted exoskeletons adopt an anthropomorphic structure similar to that of the human body, with few considerations for non-anthropomorphic structures. In this article, a typical anthropomorphic 5-DOF power-assisted upper-limb exoskeleton for material handling was designed based on the upper-limb structure of the human body. On this basis, the joints were analyzed and optimized to reduce the self-weight and ensure the load capacity and the workspace. Then, a non-anthropomorphic 3-DOF upper-limb exoskeleton applied in an industrial setting was proposed, which internally rotated the traditional humanoid elbow joint \(90^{\circ}\). The shoulder was modeled as a 2-DOF joint, and the elbow was modeled as a 1-DOF joint. The proposed exoskeleton can improve the force status of the elbow, reduce the required torque and power consumption of the elbow joint when carrying the load in industrial settings, and thus reduce the size and weight of the elbow joint actuator. The paper is structured as follows. Section 2 gives the principle of the 5-DOF upper-limb exoskeleton and the 3-DOF upper-limb exoskeleton. The differences and the singularity are analyzed. In Section 3, the forward and inverse kinematics analysis based on workspace is presented. Section 4 illustrates the dynamic analysis of the joint torque and power consumption. Section 5 presents the experimental results of the exoskeleton prototypes. In Section 6, the authors draw conclusions and provide directions for future work.