Human body enhancement is an interesting branch of robotics. It focuses on wearable robots in order to improve the performance of human body, reduce energy consumption and delay fatigue, as well as increase body speed. Robot-assisted equipment, such as wearable exoskeletons, are wearable robot systems that integrate human intelligence and robot power. After careful design and adaptation, the human body has energy-saving sports, but it is an arduous task for the exoskeleton to achieve considerable reduction in metabolic rate. Therefore, it is necessary to understand the biomechanics of human sports, the body, and its weaknesses. In this study, a lower limb exoskeleton was classified according to the power source, and the working principle, design idea, wearing mode, material and performance of different types of lower limb exoskeletons were compared and analyzed. The study shows that the unpowered exoskeleton robot has inherent advantages in endurance, mass, volume, and cost, which is a new development direction of robot exoskeletons. This paper not only summarizes the existing research but also points out its shortcomings through the comparative analysis of different lower limb wearable exoskeletons. Furthermore, improvement measures suitable for practical application have been provided.

With the increasing utilization of portable electronic devices and wearable technologies, the field of human motion energy harvesting has gained significant attention. These devices have the potential to efficiently convert the mechanical energy generated by human motion into electrical energy, enabling a continuous power supply for low-power devices. This paper provides an overview of the fundamental principles underlying various energy harvesting modes, including friction-based, electromagnetic, and piezoelectric mechanisms, and categorizes existing energy harvesting devices accordingly. Furthermore, this study conducts a comprehensive analysis of key techniques in energy harvesting, such as mode selection, efficiency enhancement, miniaturized design of devices, and evaluation of energy harvesting experiments. It also compares the distinct characteristics of different energy harvesting modes. Finally, the paper summarizes the challenges faced by these devices in terms of integrating human biomechanics, achieving higher energy harvesting efficiencies, facilitating micro-miniaturization, enabling composite designs, and exploring broader applications. Moreover, it offers insights into the future development of human motion energy harvesting technology, laying a theoretical framework and providing a reference for future research endeavors in this field.

This paper focuses on the dynamic responses of a planar mechanism with multiple clearance joints. The effect of the impact between the journal and the bearing in the clearance joint is described using an improved impact force model, and a typical four-bar linkage mechanism with multiple clearance joints is presented as an example. Two conditions are considered in this research, one is the single clearance joint with different position, and the other is multiple clearance joints. From a large number of numerical results, some important conclusions are obtained as follows: (1) with the influence of the clearance joint, the dynamic output of system has obvious vibration in comparison to the ideal value. (2) The position of the clearance joint has a clear effect on the response of system; the larger the distance of the clearance joint from the drive motor, the smaller its influence on the output of the system. (3) With the increase in the clearance joint number, the dynamic stability of the multibody system is decreased gradually, and the dynamic characteristic of the system also appears as obvious nonlinear phenomenon. (4) The coupling phenomenon appears when multiple clearance joints in the multibody system are considered, which should be examined seriously during the process of design and numerical analysis.

Long-term manual material handling (MMH) work leads to the trend of the younger onset of work-related musculoskeletal disorders (WMSDs), with low back pain (LBP) being the most common, which causes great trouble for both society and patients. To effectively prevent LBP and provide support for workers engaged in MMH work, wearable lumbar assistive exoskeletons have played a key role in industrial scenarios. This paper divides wearable lumbar assistive exoskeletons into powered, unpowered, and quasi-passive types, systematically reviews the research status of each type of exoskeleton, and compares and discusses the key factors such as driving mode, mechanical structure, control strategy, performance evaluation, and human–machine interaction. It is found that many studies focus on the assistive performance, human–machine coupling coordination, and adaptability of wearable lumbar assistive exoskeletons. At the same time, the analysis results show that there are many types of performance evaluation indicators, but a unified and standardized evaluation method and system are still lacking. This paper analyzes current research findings, identifies existing issues, and provides recommendations for future research. This study provides a theoretical basis and design ideas for the development of wearable lumbar assistive exoskeleton systems.

The article introduces a general solution for dynamic analysis of a planar multibody system with revolute lubricated clearance joint. An improved transition force model is established, which includes dry contact force and hydrodynamic forces, accounts for not only squeeze-film effects but also wedge-film effects, and is applicable to both long and short bearings. Then, the dynamic behaviors are presented based on this transition force model and a planar slider-crank mechanism with a lubricated revolute clearance joint. Different test conditions are considered in order to present a parametric study about the effects of clearance size, crank speed, and lubricant viscosity on the dynamic characteristics of planar multibody system with lubricated revolute clearance joint. As shown by numerical simulation results, it can be included that with larger clearance size and crank speed, as well as smaller lubricant viscosity, the system has higher vibration amplitude and lower minimum film thickness.

In order to reduce the impact of knee injury and energy consumption during exercise, an unpowered exoskeleton was proposed based on the characteristics of ergonomics and human lower limb gait. The device is assisted by a double spring mechanism and worn parallel to the knee joint. The metabolic energy of the human body is reduced by compensating for the energy loss the lower limbs negative work. At the same time, the elastic energy storage element is simulated and analyzed in ANSYS software, and the corresponding relationship between the size of energy storage unit and strain energy is determined, so as to realize the parameter matching design and application of energy storage unit. Finally, the effectiveness of the exoskeleton is proved by analyzing EMG data and human knee torque data. The experimental results showing that the exoskeleton has a good assistant effect, and can achieve the purpose of daily walking assistance.