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Journal of ZheJiang University (Engineering Science)  2023, Vol. 57 Issue (10): 2042-2050    DOI: 10.3785/j.issn.1008-973X.2023.10.013
    
Online decoupling technology of six-dimensional force sensor based on EtherCAT bus
Hao ZHA1(),Shao-hua FEI2,Yun FU3,Zhen LV4,Wei-dong ZHU2,*()
1. Polytechnic Institute, Zhejiang University, Hangzhou 310015, China
2. College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China
3. Zhejiang Xizi Spirit Aviation Industry Ltd., Hangzhou 311228, China
4. Zhejiang University City College, Hangzhou 310015, China
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Abstract  

A six-dimensional force sensor data acquisition module based on EtherCAT bus was designed, overcoming the drawbacks of traditional modules, like large size, low accuracy, and absence of data processing. The module had small size, high precision, high real-time, fast acquisition speed and integration of acquisition and processing. A neural network optimized by genetic algorithm, was developed for offline training of experimental data, so as to decrease the inter-dimensional coupling of six-dimensional force sensor. Multiple randomization was used to enhance the generalization performance of the algorithm, and the trained parameters were transplanted to the microcontroller for the online decoupling. Through single-dimensional and six-dimensional force sensor loading experiments, the result indicated that the data acquisition and processing could be achieved by module within 1 ms. Relative error was less than 0.85% after decoupling, the accuracy improved by 37.1% compared to the least squares decoupling matrix calculation.



Key wordsEtherCAT      six-dimensional force sensor      genetic algorithm      neural network      online decoupling     
Received: 20 December 2022      Published: 18 October 2023
CLC:  TP 212.6  
Fund:  浙江省“尖兵”“领雁”研发攻关计划资助项目(2022C01134)
Corresponding Authors: Wei-dong ZHU     E-mail: zhahao@zju.edu.cn;wdzhu@zju.edu.cn
Cite this article:

Hao ZHA,Shao-hua FEI,Yun FU,Zhen LV,Wei-dong ZHU. Online decoupling technology of six-dimensional force sensor based on EtherCAT bus. Journal of ZheJiang University (Engineering Science), 2023, 57(10): 2042-2050.

URL:

https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2023.10.013     OR     https://www.zjujournals.com/eng/Y2023/V57/I10/2042


基于EtherCAT总线的六维力传感器在线解耦技术

为了克服传统六维力传感器数据采集模块体积大、精度低、缺乏数据处理功能的弊端,设计了一种体积小、精度高、实时性高、采集速度快、采集处理一体化的基于EtherCAT总线的六维力传感器数据采集模块. 为了减小六维力传感器的维间耦合,开发了遗传算法优化的神经网络来对实验数据进行离线训练. 利用多重随机操作来提高算法的泛化性能,并将训练好的参数移植到微控制器中进行在线解耦. 通过单维和六维力传感器加载实验,表明模块可在1 ms之内完成数据的采集及处理;解耦后相对误差在0.85%以下,相对于最小二乘法解耦矩阵计算得到的精度提高了37.1%.


关键词: EtherCAT,  六维力传感器,  遗传算法,  神经网络,  在线解耦 
Fig.1 Internal structure diagram of six-dimensional force sensor
Fig.2 Hardware composition diagram of six-dimensional force sensor data acquisition module
Fig.3 Principle block diagram of slave station
Fig.4 Program initialization flowchart of six-dimensional force sensor data acquisition module
Fig.5 Allocation and mapping of process data object
Fig.6 Acquisition flowchart of process data
Fig.7 Structure diagram of neural network
Fig.8 Neural network algorithm optimized by genetic algorithm
Fig.9 Flowchart of online decoupling
Fig.10 Site diagram of six-dimensional force sensor data acquisition experiment
通道 相对误差/% 通道 相对误差/%
Fx 0.083 5 Mx 0.135 6
Fy 0.225 7 My 0.191 1
Fz 0.135 6 Mz 0.128 4
Tab.1 Data relative error of single dimensional loading experiment
通道 相对误差/% 通道 相对误差/%
Fx 0.364 7 Mx 0.312 6
Fy 0.364 7 My 0.416 8
Fz 0.416 8 Mz 0.312 6
Tab.2 Data fluctuation characteristics of single dimensional loading experiment
Fig.11 Linearity characteristic diagram of single-dimensional loading experiment
Fig.12 Six-dimensional loading experiment of six-dimensional force sensor
Fig.13 Relative error diagram of prediction force of six dimensional loading experiment
通道 相对误差/% 通道 相对误差/%
Fx 1.150 2 Mx 1.028 5
Fy 1.350 8 My 0.949 1
Fz 1.294 0 Mz 1.270 6
Tab.3 Calculation error of least squares decoupling matrix
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