| In recent years,with the rapid development of intelligent robot technology,it has been widely used in all walks of life.How to make robots develop in a more autonomous and intelligent direction,and make them have independent and autonomous behaviors similar to human beings and complete tasks excellently has become the current research focus.At present,scientists are studying the application of mechanical sensing system in the wrist and other joints of intelligent robots,these mechanical sensing units can detect the force of the robot when it contacts with objects.At the same time,the demand for special function robots in special industries is also increasing,such as earthquake relief robots,fire fighting robots and micro robots for medical science.The perception of external forces is the premise to ensure the stable balance and normal work of these robots,so it is of great significance to apply stress sensors to the wrist of robots to ensure stable work.Traditional resistive and capacitive stress sensors are susceptible to electromagnetic interference,corrosion and high temperature and high pressure,so they cannot be used normally in complex environments.Compared with traditional sensors,FBG has the characteristics of anti-electromagnetic interference,strong corrosion resistance,small volume and high sensitivity,and has been widely used in medical devices,intelligent wearable devices,robotics,aerospace and other fields in recent years.It has great potential in replacing traditional sensors.In this paper,the status quo of fiber Bragg grating(FBG)stress sensor is analyzed,and a multi-dimensional force sensor technology based on fiber Bragg grating method for robot wrist force analysis is studied.Firstly the research status of fiber optic stress sensing technology at home and abroad is analyzed.The sensing principle and demodulation technology of fiber grating are studied.Two kinds of multi-dimensional force sensors for robot wrist are proposed according to the requirements of robot wrist for force perception.The sensing principle of the sensor is analyzed.The sensor model is established by Solid Works,and the mechanical simulation analysis of the sensor is carried out by ANSYS.The stress and strain distribution of the sensor was studied to determine the optimal packing position of the fiber Bragg grating.We analyzed the linearity and sensitivity of the sensor and the relationship between the central wavelength drift of the grating used by the sensor and studied the force on different parts.In order to solve the problem that the accuracy of the stress sensor is affected by the influence of the fiber Bragg grating on the temperature sensitivity,a temperature compensation scheme is proposed,we build a temperature sensing experiment platform,the temperature sensing experiment is carried out,the temperature sensitivity coefficient of the fiber Bragg grating is measured,and the influence of the temperature change on the stress test of the sensor is eliminated.Experimental results show that the maximum sensitivity of the sensor is 15.9 PM /N.The maximum measurement error is within 3%.The sensor has the advantages of high sensitivity,strong electromagnetic interference resistance,high temperature resistance,and can be used in complex environment.At the same time,it can detect the environment temperature,and realize the measurement of stress and temperature parameters.It is of great significance for robot wrist force analysis,grasping objects and realizing various functions.Finally,we summarized and analyzed the research results,pointed out the current shortcomings,and the following research contents and assumptions are put forward. |
