High Payload Manipulator Design With Active And Passive Safety Control For Nursing Tasks

With the increasing aging of the society and the insufficient number of nurse,it is urgent to develop robots that can replace or assist the nurse to complete the care work.The working environment of nursing robots is dynamic and unstructured,and the working object is the disabled elderly.Therefore,the environmental perception ability of nursing robots and the reliability of human-robot interaction have become the research difficulties and hot spots.This paper develops a six degree-of-freedom(DOF)manipulator with flexible skin,which has a compact structure and high payload,and it can lift the disabled elderly from the bed.The flexible skin on the surface of the arm has tactile and proximity perception,the robot can perform nursing tasks safely and reliably by using the proposed active and passive safety control method.According to the requirements of lifting disabled patient,the configuration and performance indexes of the high payload manipulator are determined.A double DOF joint scheme based on multi-stage deceleration is proposed,a six DOF manipulator is designed,and the key components are selected according to the design indexes.The kinematic model of the manipulator is established,and its reachable operation space is analyzed.In order to improve the safety of human-robot interaction,a skin sensing system with tactile and proximity sensor is designed,different types of tactile sensors and proximity sensor characteristics are analyzed and selected.According to the working characteristics of the sensor,acquisition circuits board of tactile and proximity sensor is designed and tested.A flexible skin substrate of honeycomb is designed that not only protects the sensor,but also improves comfort and safety in human-robot contact.According to skin sensing system of robotic arm,an active and passive safety control method applied is proposed.Method of avoiding obstacles and approaching safety of the manipulator based on the fuzzy control theory is designed,so as to improve the active safety of the manipulator.The possible dangerous situation in the nursing task is analyzed.Through the pressure information fed back by the tactile sensor,the joints of the manipulator are controlled and adjusted to the action state when holding the patient task,so as to realize the active and passive safety of the manipulator.On the basis of the above work,the prototype integration and experimental platform of the high payload manipulator is completed,and the performance test of the manipulator and the experimental of the active and passive safety control method are carried out,including the load performance and repeat positioning accuracy of the manipulator.Then different experimental scenes are designed,and the active obstacle avoidance,safety approach and attitude adjustment experiments are carried out,the experimental results show that the designed high payload manipulator performance and active and passive safety meet the requirements of nursing tasks.