Research On Spokes Piezoelectric Six-dimensional Force Sensor Based On Fault-tolerant Mechanism

Six axis force / torque sensor is a kind of device with the ability of sensing spatial external force / torque information.Six axis force sensors are widely used in aerospace,industrial robots,heavy equipment manufacturing and other fields.The working environment of six axis force sensor is complex and harsh.Environmental factors or human factors may lead to the failure of six axis force sensor.It is difficult or impossible for people to detect and repair the fault of the six axis force sensor in the process of carrying out the measurement task.It may make the system unable to accurately complete the real-time measurement of the external force vector information and other tasks,and resulting in huge economic losses and even serious casualties.Most of the existing sensors only have the ability of accurate measurement.They can not continue to work when there is a failure.Which limits the development of intelligent manufacturing equipment.Therefore,the basic theory of six axis force sensor with fault tolerance measurement ability is studied.A fault-tolerant measurement method of piezoelectric six axis force sensor with redundant branches is proposed based on the principle of multi-point measurement and fault-tolerant measurement in this paper.The deformation law of force sensing element of six axis force sensor under space external force load is analyzed from the point of view of mechanics.The mapping relationship between the force of the force sensitive element and the external force in space is derived.The sensor fault free measurement model and fault measurement model are established.The feasibility of the measurement principle is verified by the ability of ANSYS finite element software to simulate and solve real engineering.A spoke sensor structure is designed based on the fault-tolerant measurement mechanism of sensor.The process of load transfer on the surface is analyzed.The model of its static and dynamic analysis is established.The theoretical formulas of charge sensitivity and natural frequency of the sensor are derived.The influence law of the size design parameters of the structure on the measurement performance of the sensor is obtained through the finite element simulation analysis.The structure of the sensor is optimized based on genetic algorithm.The static and dynamic simulation of the final size parameters is carried out.The sensitivity and natural frequency are calculated.The sensor prototype is processed and manufactured.The calibration system of six axis force sensor is built.The static and dynamic calibration experiments of six axis force sensor are carried out.The performance index of the sensor is obtained.It will produce large error when the sensor makes fault-tolerant measurement.So the nonlinear decoupling algorithm of six axis force sensor is studied.The experimental data are used as samples for verification.