Design And Comfort Experiment Of Multi-arm Cooperative Nursing Robot

The accelerated aging of the population and the shortage of nursing staff have brought severe challenges to the elderly support and patient care.The application of nursing robots can effectively improve the quality of nursing service,reduce the burden of nursing staff and reduce the probability of secondary injury in the nursing process.In this paper,aiming at realizing the shift task of holding in the process of nursing operation,combined with the shortcomings of the dual-arm holding robot,a new mechanism scheme of holding nursing robot is proposed.The kinematics,simulation analysis and prototype development of its body mechanism are carried out,and the human-computer interaction comfort in the process of four-arm holding is studied.The main research contents are as follows :Firstly,starting from the actual nursing task,the task requirements of the nursing robot are analyzed,which requires the robot to have the characteristics of high comfort,large carrying capacity,large working space and self-balancing of the body.Based on the design requirements of nursing robot,a new type of four-arm cooperative holding nursing robot mechanism was designed,including four-arm holding linkage mechanism and selfbalancing large workspace pitching linkage mechanism.The statics,kinematics,simulation analysis and scenario simulation of each linkage mechanism were carried out to verify the feasibility of robot principle and mechanism motion.Secondly,the mapping relationship between human posture and local contact pressure is studied,and the mechanical model of human body and the mechanical equation of fixed posture under four-arm bracket are established.Then the relationship between four-arm load distribution and different postures and different bracket positions is obtained.Based on the human body mechanics model,the human body compression and joint torque under the condition of double arm and four arm bracket are compared and analyzed to verify the characteristics of high comfort of four arm bracket.In addition,based on the Lagrange method,the dynamic model of the robot holding the human body is established.Thirdly,the engineering transformation and the development of the principle prototype of the multi-arm cooperative holding nursing robot are carried out.The holding simulation experiment of the principle prototype is carried out to verify the feasibility of the mechanism,and the appearance of the robot is designed.In addition,the experimental prototype of the robot is designed and developed to build a platform for subsequent experiments.On this basis,considering subjective and objective factors,the experimental design of four-arm holding comfort was carried out to determine the purpose and method of the experiment.The objective and subjective data of the experiment were collected and processed by building the EMG measurement system,the attitude recognition system and the body pressure measurement system.The activation degree of three muscles and the local compression degree of four contact arms in 25 groups of experiments were obtained,and the subjective evaluation scores of five parts in each group of experiments were obtained.The EMG data were summarized by designing the GUI interface.Finally,using the analytic hierarchy process(AHP)and principal component analysis(PCA),the comfort evaluation model is established.Through the comprehensive analysis of the subjective and objective evaluation function,the comfort range and uncomfortable range of each joint of the human body under the four-arm holding state are obtained,and the most comfortable holding posture is determined.The results show that the hip joint angle is relatively comfortable in the range of 90° – 135° under the holding posture,and discomfort occurs when the hip joint angle is greater than 135°.The posture angle is relatively comfortable in the range of 0° – 25°,and discomfort occurs when the posture angle is less than 20°.The comfort is the highest when the hip joint is 125° and the posture angle is 25°.The work in this paper provides a reference for the design and development of a new generation of multi-arm collaborative holding nursing robot.