Indirect measurement of upper limb load for users of four-wheeled mobility aids based on torque sensors

Assistive walking devices are widely used, and the four-wheeled walker (FWW) is one of the most commonly used assistive devices to improve the stability and walking ability of users. In order to study the changes in upper limb joint torques when users use the FWW in their daily life, we developed a torque sensor-based FWW instrumentation system to monitor and collect force and torque information from the wrist and to build the corresponding biomechanical model. In this experiment, experimental data were collected from 10 healthy young people under six assisted walking modes. The upper limb kinematic data were collected and processed by Vicon Nexus software, and the angular conversion was performed to obtain an upper limb kinematic model consistent with FWW-assisted walking. Based on the kinematic data, the internal joint torques of the upper limb in three clinical planes were determined using the inverse kinematic method. The results show that there are significant differences in the joint angles and joint torques of the human upper extremity under different assisted walking patterns of difficulty that require the user's attention during assisted walking to prevent additional injuries. The standardized data provided by this experiment will help people to improve the usage of FWW and further optimize the FWW mechanics.