Research On Multi-axis Force Calibration Method And System Based On The Flotation Principle

Three-dimensional flexible tactile sensor has its own special requirements for loading method when it is calibrated. The open-loop load calibration method represented by weight load is more complicated to operate. The loading device error is directly delivered to the load force, which leading to the load accuracy is difficult to improve; it is easy to operate in real-time measurement of calibration force for closed-loop load calibration method by using six-axis force/three-axis force sensor, and the load accuracy is only subject to the accuracy of six-axis force/three-axis force sensor which isn’t affected by the loading device error.The difficulty of flexible tactile sensor calibration based on six-axis force is the measurement accuracy of six-axis force. In view of the existing six-axis force sensor measurement accuracy is difficult to meet the calibration accuracy requirements of flexible tactile sensor array, this paper presents a flotation-type force measurement thought which designed to avoid coupling between the dimension and improve easurement accuracy in multi-axis measurements:the force on the floating plate could be measured by measuring the gas parameters of nozzle-floating plate mechanism, and designs a prototype of flotation-type six-axis force measurement platform that can calibrate the three-dimensional flexible tactile sensor. Theoretical studies and experimental results show that flotation-type six-axis force measurement platform has a high measurement accuracy, so the three-dimensional flexible tactile sensor calibration based on six-axis force can be achieved.The main content and innovative work of the paper is in the following areas:(1) the special requirement of flexible tactile sensor calibration and loading device error is analyzed, a program of flexible tactile sensor array calibration based on flotation-type six-axis force measurement is proposed in connection with high-precision flexible tactile sensor array;(2) a systematic study on the basic theory of the pressure nozzle-floating plate mechanism is carried out, a mathematical model of nozzle-floating plate mechanism is established, an experimental device of nozzle-floating plate mechanism is developed, and the experiments verify the correctness of the theoretical study;(3) The affect of nozzle orifice diameter, the diameter and the depth of the pressure chamber, nozzle diameter and gas film thickness and gas pressure on the static characteristics of the nozzle-floating plate mechanism is analyzed with Fluent software simulation, and an optimization scheme of nozzle structure size is proposed according to the simulation data;(4)a flotation-type six-axis force measurement platform is designed and made, a mathematical model of nozzle-floating plate mechanism platform is researched;(5)a calibration method of flotation-type six-axis force measurement based on gravity load of floating plate and the calibration problem of flotation-type six-axis force measurement platform is solved. In this paper, we draw the following conclusions:flotation-type force measurement platform contains no coupling between the dimension which is consistent with theoretical expectations; the space force measurement error is:the size of the force error <0.2%, direction of the force error <0.5°, Point error of the force≤±0.05mm, and they meet the calibration requirements of flexible tactile sensor array.The significance of flotation force measurement methods and flotation-type six-axis force sensor is not limited to solve the problem of three-dimensional flexible tactile sensor calibration. As a new force measurement approach, flotation force measurement has a unique prospect in the field of multi-axis force measurement, The breakthrough of the flotation-type multi-dimensional force measurement on the measurement accuracy has a significance on many related fields.The results of research have a universal application on a variety of flotation multidimensional force sensor design.