Design And Research Of A Strain Type Plantar Force Measuring Unit

The measurement of the interaction force between the foot and the ground is the most comprehensive way to obtain the information of the foot force in the field of human motion research.The interaction between the foot and the ground can can be used to model the human body movement.It has great significance for improving the effect of exercise training,diagnosis of diseases and rehabilitation training.At present,most of the measuring devices not only has more elastic components,but also is more expensive because of implementing by setting multiple force measuring devices.Therefore,the paper proposes a new method which based on elastic beam strain to reflect the foot force for the foot force measuring device,and a single measuring unit can measure the distribution of two plantar forces simultaneously.The following researches are carried out in this paper:1.The measuring device of the foot force is designed.Through mathematical modeling and finite element simulation,the measuring principle and structure design of the force measuring foot are selected.Theoretical analysis proves that the parallel beam structure is better than the single beam structure,and the force foot structure is determined.By analyzing the measuring principle of the force measuring unit through the mechanical model,it is obtained that the output strain on the force measuring foot can be expressed by the cubic polynomial of distance a and b,and is linearly proportional to the loading force F.2.The measuring principle of force measuring unit is studied.Through the single factor finite element simulation analysis and data fitting of the force measuring unit,the output strain and the loading force are obtained in a square relationship,which is in a cubic relationship with the coordinate of the loading force position X and Y.A mathematical model for calculating the distribution of the foot force is established.The structure of the device was simulated and optimized through the orthogonal experiment,and the thickness of the planar support plate and the size of the force foot were determined.The relationship between strain and force size and position is simulated and calculated theoretically.The error when calculating one force is less than 1%,and the error when calculating two forces is less than 3%.It is proved that the force measuring unit can accurately measure the magnitude and position of the foot force.3.The signal acquisition system is designed and verified by experiment.The hardware and software of the signal acquisition system are designed and the output voltage is obtained by constructing the wheatstone bridge.The performance of the measurement system was tested,and the measurement error was less than 0.4uv,meeting the requirements of experimental measurement.After loading multiple groups of forces,the output voltage and the loading force are obtained in a square relationship,which is in a cubic relationship with the coordinate of the loading force position X and Y.Using the corresponding relationship between the output voltage and the loading force,the magnitude and position of the loading force are calculated,and the experimental error is less than 5%.Through the analysis of the experimental data,the measurement error of the loading force is within the allowable range,which indicates that the measuring device can recognize the magnitude and location information of the loading force,and proves the effectiveness and accuracy of the measuring device and the measuring method.