On The Design And Assessment Of A Wearable Load-carrying Device

Automation equipment has been widely used in the logistics and manufacturing industry,however,material materials handling(MMH)is still available in our daily life,being considered as an important factor of occupational musculoskeletal injuries.Over the years,several of assistive device and load-carrying equipment have been developed for risk prevention,energy reduction,mobility improvement,and enhancement of comfort in manufacturing and other high demand industries such as logistics,medical environment and safety.With the benefit of mobility,efficiency and usability,the werable assistive device is becoming one of the most popular areas.In this thesis,after examing the biomechanical model of MMH,an ergonomic experiment was organized to analyse the demands of assist from the device.A wearable load-carrying device(WLCD)was designed and assessed based on a human-device interface.The main contents of this thesis include:(1)Combining theoretical and experimental study of manual handling mechanism,kinematics and kinetics,hand load and surface electromyography was analysed for the development of an assist strategy based on force conduction.(2)An insole plantar pressure system(iPPS)was generated using film pressure sensors for measureing movement information such as plantar pressure and joint angles.A gait experiment was implemented for gait phase detection and pressure-angle model.Based on a gene expression program,prediction model of correlational relationship between joint angle and plantar pressure was generated.(3)After analyzing the "human centered" conception and guildlines for MMH elements design,three types of assistive strategies including the use of load transfer,torque transfer and energy transfer were presented to help transfering the load from hand to the body.The prototype of the WLCD was customized including upper arm assistant,low back assistant and lower extremity assistant under based on the human-device interface of iPPS.(4)Three experiments were conducted to assess the ergonomical function of WLCD.For repeated lifting tasks,low back muscle activity and heart rate were significantly reduced for 7kg,14kg,and 21kg load and rang of motion for hip was significantly reduced for 14kg load.The maximum acceptable weight of lifting was increased from 15.44kg to 16.56 kg while wearing WLCD in a high frequency task.For load carrying task at 15kg,the mean heart rate,normalized oxygen uptake,minute ventilation and peripheral rating of perceived exertion were significantly lower by 6.6%,8.0%,11.8%and 13.9%respectively in WLCD condition when compared to the no device condition.