| In order to experience rich haptic sensations in virtual reality and human-computer interaction,the research on haptic simulation technology is getting more and more advanced.Piezoelectric haptic feedback devices have outstanding advantages,but the mechanism of haptic modulation based on piezoelectricity is still not perfect.There are two main effects to explain the haptic modulation mechanism,one is the air squeeze film effect,and the other is the intermittent contact effect.To address the incompleteness of the kinetic modeling of the air squeeze film effect and the intermittent contact effect,this paper improves the kinetic models of these two effects,integrates the contribution of these two effects to the friction modulation,and establishes the friction modulation equation,which can reflect the changing trend of the friction force under different frequencies and amplitudes.The free vibration analysis and forced vibration analysis of the piezoelectric touch beam were carried out,and the modal analysis and transient analysis of the piezoelectric touch beam were carried out in ANSYS to verify the correctness of the theoretical calculation.The kinetic model of intermittent contact effect was established,which can reflect at which frequency and amplitude intermittent contact will occur between finger skin and touch beam,and the expression of the average interaction force between finger skin and touch beam was derived.The first contact model and the second contact model of the finger and the touch beam were established,and the kinetic model of the air squeezing membrane effect was developed according to the Reynolds equation.The analytical solution of the pressure in the membrane of the first contact model and the numerical solution of the pressure in the membrane of the second contact model were obtained.It was verified that the pressure obtained by the second contact model was more accurate,and the effects of system parameters such as frequency,amplitude and skin epidermal ridge height on the pressure in the squeezed membrane were analyzed.Based on the kinetic model of intermittent contact effect and air squeeze film effect,the coupling relationship between these two effects was inferred and the friction modulation equation was established.The variation of the relative friction coefficient between finger skin and touch beam at different frequencies and amplitudes was analyzed.According to the friction modulation mechanism,a two-dimensional haptic feedback device was designed,which can realize a relatively rich tactile feedback.The amplitude and friction measurement platform was built to verify the correctness of the forced response analysis and amplitude superposition theory by measuring the amplitude of the touch beam.Then the friction force between finger skin and the touch beam was measured at different excitation frequencies and amplitudes,and the friction force data were analyzed and processed to verify the rationality of the friction modulation equation establishment.Finally,the haptic evaluation experiments of the haptic feedback device were conducted to verify that the device can achieve a relatively rich haptic feedback. |
