Research Of Multi-dimensional Force Sensing Technology Based On Fiber Bragg Grating

Multi-dimensional wrist force sensor is one of the important external sensors for robot. It is installed in wrists and ankles in operator of robot, and it can be used to sense the contact force between operator and external environment. Wrist force sensor is an important source of information for robot perception of the role of environmental force characteristics. The test on wrist force of walking robot ankle joints help to intelligent robot posture, movement and accurate control of environment awareness. This requires force sensor owns many advantages such as high sensitivity in each axis, small cross-axis sensitivities and good static and dynamic characteristics, etc. If we use fiber Bragg grating as the sensing element design a force sensor, it will be used in strong electromagnetic fields or corrosion harsh and other special environments. And it can meet the needs of the actual operating environments of the robot. Therefore, design a multidimensional wrist force based on FBG has very important significance. The force sensor should be a relatively simple structure and can be meet the needs of robot in a harsh environment.An ankle force sensor based on FBG is introduced in this paper. The static and dynamic characteristic of the elastic body is obtained by finite element analysis. Then the distribution of stress and strain of elastic under different force and torque in each direction are obtained. And we calculate the sensitivity of sensor under single way force is0.265pm/N. Modal analysis of the sensor elastic structure is conducted by ANSYS. and we can obtain the vibration characteristics of the sensor structure, the natural frequencies and mode shapes of the first six orders are given. Transient analysis of the sensor elastic structure is conducted too. We can see the deformation of elastic structure under different dynamic loads.Considering the actual needs of walking robot wrist force sensor, the number of fiber bragg grating and the paste process of FBG, the multi-dimensional wrist force sensor can be designed. On the basis of ANSYS simulation, the mechanical structure of the sensor is designed and manufactured, FBG is layed, and simulation measurement system is built in the lab. In the pressure and torque experiment machine, we conduct a series of static testing. According to the force situation of robot ankle in the actual walk. a series dynamic impact experiments are conducted. The FBG static and dynamic demodulation test system is established. We analyz a large number of test data from the experiments and extracted features, then the characteristics of the sensor are obtained. The results demonstrate that the force sensor is simple in structure, corrupting EMI (Electro-Magnetic Interference), high stability, high sensitivity, low cost and worths extension. The couple between force/torque and signals is negligible.