| Due to the deterioration of physical fitness or various diseases,the aging population has a high proportion of lower limb disability.It is difficult for those seniors to complete the transfer of any two places without the help of others.And the transfer nursing robot can effectively solve the above problems.However,most of these nursing robots represented by transfer devices are inconvenient to use and cannot effectively meet the safety and comfort of users during the completion of the task.At the same time,safety and comfort are important conditions and mandatory requirements that must be met during the movement of this type of robot.In addition to optimizing the structure of the robot,the motion control algorithm should also have relevant capabilities.Impedance control is a compliant control method of force-displacement conversion,and it has certain potential ability to ensure the safety and comfort of assisted person.At present,it is mostly used in industrial robots.However,in the field of human-robot interaction of nursing robots,it is rarely used due to the complex structure of human-robot system and the uncertain range of ideal human-robot interaction force.The main content of this thesis is based on the human-imitating transfer nursing robot and to plan the movement track of the manipulator in the process of human-robot interaction,and to establish a human-robot mechanical model to analyze the characteristics of force and to determine the impacts on the subjective comfort factors and range of the assisted person.The human-robot impedance model is completed and a control scheme that can be used for the movement process of the nursing robot is proposed.The safety and comfort of the assisted person are ensured.Firstly,the kinematics analysis of the human-imitating transfer nursing robot is performed to acquire the correlation of the driving device and the spatial posture of the manipulator.The selection mechanism of trajectory based on the physical characteristics of the assisted person is established;Secondly,the human-robot mechanical model is established to analyze the relationship of the human-robot interaction force and manipulator.The connection of human-robot interaction force,subjective comfort and the spatial posture of manipulator determined.The subjective comfort is used as the control basis and target.Thirdly,the human-robot impedance control system model is established to describe the relationship between the assisted person and the robot.Combined with the actual needs of the transfer robot,the simulation is used to determine the impedance parameters with excellent response.Finally,the motion control system for the transfer nursing robot is constructed and the impedance control program is completed.The impedance controller system is verified through experiments.On the basis of the above studies,a plurality of sets of manipulator motion trajectories with the body characteristics of the assisted person as the selection parameter are determined for the human-imitating transfer nursing robot.The human-robot mechanics model is established to analyze the correlation between the human-robot interaction force,subjective comfort and the spatial posture of the manipulator.The main influencing factors of comfort is defined and regarded as the control basis of the human-robot impedance control system.With the impedance control,the transfer nursing robot can adjust the spatial posture of manipulator according to the human-robot interaction force to meet the comfort demand.The experimental results show that the transfer nursing robot with impedance control has a remarkable evaluation compared with the regular motion control. |
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