Research On The Optimization Design Of Integrated Torque Sensor For Cooperative Manipulator

Under the background of the era when countries vigorously promote intelligent production,robot-related technologies are developing rapidly,and people begin to expect robots that can work with people in the fields of medical care,education,service,aerospace,etc.Thus,collaborative robots emerge.Collaborative robots can work collaboratively with people in the same environment to greatly improve manufacturing efficiency.However,without the protective isolation cover of traditional industrial robots,the safety of cooperative robots face severe tests.In order to ensure the safety of cooperative robots,it is necessary to install torque sensors to obtain the force of joints when the robot is working,in order to avoid danger.More and more people pay attention to how to design a torque sensor structure with better comprehensive performance for dexterous collaborative robots.After investigating and analyzing the typical application of collaborative robot torque sensors,this paper intends to design a strain-type torque sensor with simple structure,compact size,high sensitivity and large range,which is suitable for the existing nine-degree-of-freedom collaborative robot arm in the laboratory.First of all,this article comprehensively compares the application characteristics and shortcomings of the five typical types of torque sensors,determines the design scheme of strain-type torque sensors,and formulates the design requirements of the torque sensors according to the use requirements of the laboratory's nine-degree-offreedom manipulator.Comparing the basic configuration of the strain sensor,the integrated structure design of the output shaft and the torque sensor is proposed,the sensor elastomer material is selected through analysis and comparison,and the overall installation design of the sensor is completed according to the structural characteristics of the mechanical arm joint.Secondly,in order to improve the sensitivity of the sensor,the elastic body of the sensor is mechanically modeled and analyzed,and the functional relationship between sensor load and deformation is deduced.The waist-shaped hole structure is designed by the principle of stress concentration,and the average strain of the strain gauge is increased.Analyze and determine the sensor optimization target and variable parameter range,establish the sensor optimization mathematical model,design the optimization test according to the BBD design method,establish the response surface model to solve the optimization model,and use the static finite element simulation to check and verify.Thirdly,the measurement bridge scheme of the strain gauge is designed,the mapping relationship between the output voltage of the strain-type torque sensor and the strain is deduced,the nonlinear error of the measurement circuit is analyzed,and the four-arm differential circuit is drawn up to reduce the error.Finally,analyze and compare the commonly used strain gauge types,select the appropriate strain gauge model,design the paste process,and complete the processing of the torque sensor.According to the actual joint force,this paper designs the auxiliary tool and the calibration platform for the static calibration of the torque sensor,draws up the calibration plan,and analyzes the calibration error.According to the calibration results and the performance comparison with the market sensors,the torque sensor designed in this paper has good performance,which verifies the feasibility of the integrated structure design of the output shaft and the torque sensor and optimization scheme.