CN104834380A - Flexible object tactile modeling and expressing method applied to mobile terminal - Google Patents

Abstract

The invention discloses a flexible object tactile modeling and expressing method applied to a mobile terminal. The method is characterized in that the change of a contact area between a human finger end and a touch screen is obtained in real time on the mobile terminal by utilizing a contact area detection function of the mobile terminal, then the magnitude of finger press force is calculated according to pre-marked relation between the press force and the contact area and is used for calculating tactile response and virtual flexible object deformation, then contact force is fed back to a user in virtue of a certain tactile reproduction device, and meanwhile a deformation effect is displayed on the mobile terminal. The method has the advantages that 1, the problem that traditionally, in case of touch screen-based tactile reproduction, only tangential displacement is detected, and normal direction relative displacement cannot be directly detected is solved; 2, based on a principle that acting force and counter-acting force are balanced, the accurate calculation of virtual contact force is realized; 3, by considering object hardness and the magnitude of the finger active press force, deformation rendering and touch interaction with sense of reality are realized.

Description

A kind of touch feeling model building and expression being applied to the flexible article of mobile terminal

Technical field

The invention belongs to haptic modeling field, specifically, relate to a kind of touch feeling model building and the expression that are applied to the flexible article of mobile terminal.

Background technology

Along with the continuous popularization of mobile terminal as the portable set such as smart mobile phone, panel computer, the life of people more and more be unable to do without mobile terminal, but the function of its Man Machine Interface mainly concentrate at present look, the sense of hearing mutual on, the feeling function that can provide is very limited.Power sense of touch and mobile terminal product are organically combined, can allow operator touches, perception dummy object, produce feeling of immersion, thus experience more true to nature can be brought to user.Therefore, the modeling method depending on/sense of touch of facing moving terminal becomes the study hotspot in haptic modeling field.

At present, the flexible article haptic modeling of facing moving terminal, mainly based on power feel feedback, utilizes mechanical hook-up output action power, thus realizes the expression of object compliance.But the method has special requirement to mobile terminal screen or haptic device, meanwhile, when pointing mutual with mobile terminal touch screen, being difficult to realize depth detection, can not reflecting that staff active role power is on the impact of power haptic response really.Mainly contain two kinds of methods to the calculating of the deflection of flexible article: a class is the haptic modeling based on geometry, another kind of is the haptic modeling of physically based deformation meaning.Based on the haptic modeling method of geometry, be directly change the reference mark of body surface by the method for geometry interpolation thus change body form, such as linear interpolation method and Gaussian function method of interpolation; The haptic modeling of physically based deformation meaning is from physical law, analyzes the relation of power and deformation, such as finite element method and spring-mass method.Modeling method based on geometry has speed feature that is fast, that easily realize, but can not react the physical attribute of interior of articles really, and the modeling method of physically based deformation meaning can describe the physical attribute of object, fidelity is high, but calculated amount is large, real-time is poor.These two kinds of computing method, can not realize realistic distortion simultaneously and play up and haptic interaction.

Summary of the invention

Technical matters to be solved by this invention is: utilize finger tip and mobile terminal screen contact area, calculates the size of initiatively pressing force, then calculates haptic response and the dummy object surface deformation amount of flexible article, to the more real tactile experience of people.

For solving the problems of the technologies described above, the technical solution used in the present invention divides following three steps:

Step 1) based on mobile terminal system platform, obtain the contact area of staff finger tip and touch-screen, calibrate the computing formula of finger active pressing force and finger tip contact area;

Step 2) utilize 1) the middle computing formula set up, according to the contact area size detected in real time, calculate and point initiatively pressing force size, and then calculate finger and the haptic response in touch screen interaction process.

Step 3) according to the stiffness coefficient pointing initiatively pressing force size and dummy object, calculate the deflection on dummy object surface.

Further, described step 1) in, utilize mobile-terminal platform, the contact area of Real-time Obtaining finger and mobile terminal touch screen, calibrate the computing formula of finger active pressing force and finger tip contact area, its calibration process is as follows:

First, pressure transducer is arranged on the behind of mobile terminal, gathers staff initiatively pressing force size.Meanwhile, call the function that mobile terminal system carries, finger and the contact area of touch-screen are equivalent to an ellipse, detect transverse and minor axis size, and then calculate ellipse area.Under original state, when finger contact mobile terminal screen, the force value of pressure transducer collection is F ₀, the contact area size of finger tip and screen is S ₀, wherein F ₀the pressure produced when comprising own wt and the finger tip nature contact screen of mobile terminal.When the contact area of finger tip and touch-screen changes, the active pressing force size of finger calculates according to formula (1):

$F_p=\left\{\begin{array}{cc}f\left(S_t\right)-F_0,& F_p<F_{p\max }\\ f\left(S_{\max }\right)-F_0,& F_p\&GreaterEqual;F_{p\max }\end{array}\right.$ Formula (1)

In formula (1), F _prepresent the size of the active pressing force of finger, f is the fitting function according to measuring force value and the contact area obtained, f (S _t) represent when finger tip and mobile terminal screen contact area are S _ttime finger initiatively pressing force size, S _maxrepresent the Maximum Contact area of finger tip and screen, after the active pressing force of finger is increased to certain value, initiatively the increase of pressing force does not have a great impact finger contact screen area, so setting acting force threshold value F _{p max}, when finger active pressing force is greater than F _{p max}time, F _pconstant, and the acting force of finger tip when reality pressing screen generally can not be greater than F _{p max}.

Further, utilize step 1) the middle computing formula set up, calculate the size of finger active pressing force, and then calculating mobile terminal haptic response.When staff is when pressing object, the power that the active pressing force of finger tip and object feed back to finger tip is the relation of acting force and reacting force, and namely the equal and opposite in direction of pressing force and feedback force, direction are contrary.And when being applied on mobile terminals by pressing force, due to the maximum holding capacity of touch-screen and the restriction of haptic feedback devices power output, the size of actual tactile feedback force is proportional to initiatively pressing force, but not equal initiatively pressing force.Therefore, mobile terminal haptic response power size calculates according to formula (2):

$F_o=\frac{F_{o\max }\&times;F_p}{F_{p\max }}---\left(2\right)$

In formula (2), F _orepresent mobile terminal haptic response power size, F _prepresent finger initiatively pressing force size, F _{p max}represent the maximal value of initiatively pressing force, F _{o max}represent the maximum force that haptic feedback devices can produce.

Further, described step 3) in, the deflection on dummy object surface is calculated according to finger active pressing force size.Due to when staff and dummy object mutual time, the consistance of sensation only need be reached depending on/tactile sense reproduction process, namely close in the variation tendency of sensuously seen distortion and the power experienced and true environment, and without the need to numerically completely the same, therefore deflection adopts the computing method that Function Fitting is similar to.When staff is on the touchscreen without relative sliding, dummy object produces distortion, the normal direction relative displacement of center of deformation point under staff initiatively pressing force effect, and namely object is at the deformation quantity of center of deformation point, calculates according to formula (3):

$d(x_0,y_0)=\frac{F_p}{k_n}$ Formula (3)

In formula (3), d (x ₀, y ₀) represent body surface center of deformation (x ₀, y ₀) deflection at some place, F _prepresent at (x ₀, y ₀) some place finger initiatively pressing force size, F _psize according to formula (1) calculate, k _nrepresentation is to deformation coefficient, relevant to the stiffness coefficient of object, k _nbe worth larger, under the effect of formed objects power, the deflection of generation is less.

For isotropic object, according to distributed spring-mass model, when being subject to normal force effect, acting force can be delivered to each particle of adjacent area by action center by central spring, cause adjacent particle generation relative displacement, namely in the region that deformation occurs, equal with the deformation quantity that the point on the equidistant concentric circles of center of deformation point produces.Due to the restriction of mobile terminal computing power, in conjunction with early-stage Study, the deformation quantity of each point in terminal deformed region and the distance relation from center of deformation point are equivalent to exponential function.The deformation quantity of body surface each point, calculates according to formula (4):

$d(x,y)=\left\{\begin{array}{cc}d(x_0,y_0)\&times;e^{-k\&times;L(x,y)}& ,(x,y)\&Element;D\\ 0& ,(x,y)\&NotElement;D\end{array}\right.$ Formula (4)

In formula (4), d (x, y) represents the deformation quantity of point (x, y) in deformed region, d (x ₀, y ₀) represent center of deformation point (x ₀, y ₀) deflection at place, L (x, y) represents that point (x, y) is to center of deformation point (x ₀, y ₀) distance, k represents the attenuation coefficient of tangential deformation, and the value of k is relevant with the rigidity of object, and rigidity is larger, and k value is larger, and body surface deformed region is less, and D represents body surface deformed region, and the deformation of body amount exceeding deformed region D is ignored.Being out of shape rendering effect intuitively for realizing flexible article, usually making the area of deformed region be greater than the contact area of finger and mobile terminal touch screen.

Compared with prior art, technical scheme of the present invention has following beneficial effect:

Flexible article touch feeling model building and the expression being applied to mobile terminal of the present invention, utilize the measurement of finger tip and mobile terminal screen contact area, calculate the size of initiatively pressing force, then the computation model of flexible article haptic response and dummy object surface deformation is set up, to the more real tactile experience of people.The advantage of the method is, the feature for the haptic interaction of mobile terminal: when 1) solving the tactile sense reproduction of tradition based on touch-screen, only have tangential displacement to detect, and normal direction relative displacement cannot the problem of direct-detection; 2) based on acting force and reacting force equilibrium principle, the accurate calculating of dummy contact power is achieved; 3) consider the hardness of dummy object and the size of staff active pressing force, achieve realistic distortion and play up and haptic interaction.

Accompanying drawing explanation

Fig. 1 is system framework of the present invention.

Fig. 2 is acting force of the present invention and body surface deformation intention.

Fig. 3 is the graph of relation demarcating initiatively pressing force and contact area.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail.

As shown in Figure 1, a kind of flexible article touch feeling model building and expression being applied to mobile terminal of the present invention, comprises following process:

Step 1), build mobile terminal software platform, the contact area of Real-time Obtaining finger and mobile terminal touch screen, calibrate the computing formula of finger active pressing force and contact area, its calibration process is as follows:

First, pressure transducer is arranged on the behind of mobile terminal, gathers staff initiatively pressing force size.Meanwhile, call the function that mobile terminal system carries, finger and the contact area of touch-screen are equivalent to an ellipse, detect transverse and minor axis size, and then calculate ellipse area.Under original state, when finger contact mobile terminal screen, the force value of pressure transducer collection is F ₀, the contact area size of finger tip and screen is S ₀, wherein F ₀the pressure produced when comprising own wt and the finger tip nature contact screen of mobile terminal.When the contact area of finger tip and touch-screen changes, the active pressing force size of finger calculates according to formula (1):

$F_p=\left\{\begin{array}{cc}f\left(S_t\right)-F_0,& F_p<F_{p\max }\\ f\left(S_{\max }\right)-F_0,& F_p\&GreaterEqual;F_{p\max }\end{array}\right.$ Formula (1)

In formula (1), F _prepresent the size of the active pressing force of finger, f is the fitting function according to measuring force value and the contact area obtained, f (S _t) represent when finger tip and mobile terminal screen contact area are S _ttime finger initiatively pressing force size, S _maxrepresent the Maximum Contact area of finger tip and screen, after the active pressing force of finger is increased to certain value, initiatively the increase of pressing force does not have a great impact finger contact screen area, so setting acting force threshold value F _{p max}, when finger active pressing force is greater than F _{p max}time, F _pconstant, and the acting force of finger tip when reality pressing screen generally can not be greater than F _{p max}.

Step 2), utilize step 1) the middle computing formula set up, calculate the size of finger active pressing force, and then calculating mobile terminal haptic response.When staff is when pressing object, the power that the active pressing force of finger tip and object feed back to finger tip is the relation of acting force and reacting force, and namely the equal and opposite in direction of pressing force and feedback force, direction are contrary.And when being applied on mobile terminals by pressing force, due to the maximum holding capacity of touch-screen and the restriction of haptic feedback devices power output, the size of actual tactile feedback force is proportional to initiatively pressing force, but not equal initiatively pressing force.Therefore, mobile terminal haptic response power size calculates according to formula (2):

$F_o=\frac{F_{o\max }\&times;F_p}{F_{p\max }}---\left(2\right)$

In formula (2), F _orepresent mobile terminal haptic response power size, F _prepresent finger initiatively pressing force size, F _{p max}represent the maximal value of initiatively pressing force, F _{o max}represent the maximum force that haptic feedback devices can produce.

Step 3), as shown in Figure 2, calculate the deflection on dummy object surface according to finger active pressing force size.Due to when staff and dummy object mutual time, the consistance of sensation only need be reached depending on/tactile sense reproduction process, namely close in the variation tendency of sensuously seen distortion and the power experienced and true environment, and without the need to numerically completely the same, therefore deflection adopts the computing method that Function Fitting is similar to.When staff is on the touchscreen without relative sliding, dummy object produces distortion, the normal direction relative displacement of center of deformation point under staff initiatively pressing force effect, and namely object is at the deformation quantity of center of deformation point, calculates according to formula (3):

$d(x_0,y_0)=\frac{F_p}{k_n}$ Formula (3)

In formula (3), d (x ₀, y ₀) represent body surface center of deformation (x ₀, y ₀) deflection at some place, F _prepresent at (x ₀, y ₀) some place finger initiatively pressing force size, F _psize according to formula (1) calculate, k _nrepresentation is to deformation coefficient, relevant to the stiffness coefficient of object, k _nbe worth larger, under the effect of formed objects power, the deflection of generation is less.

For isotropic object, according to distributed spring-mass model, when being subject to normal force effect, acting force can be delivered to each particle of adjacent area by action center by central spring, cause adjacent particle generation relative displacement, namely in the region that deformation occurs, equal with the deformation quantity that the point on the equidistant concentric circles of center of deformation point produces.Due to the restriction of mobile terminal computing power, in conjunction with early-stage Study, the deformation quantity of each point in terminal deformed region and the distance relation from center of deformation point are equivalent to exponential function.The deformation quantity of body surface each point, calculates according to formula (4):

$d(x,y)=\left\{\begin{array}{cc}d(x_0,y_0)\&times;e^{-k\&times;L(x,y)}& ,(x,y)\&Element;D\\ 0& ,(x,y)\&NotElement;D\end{array}\right.$ Formula (4)

In formula (4), d (x, y) represents the deformation quantity of point (x, y) in deformed region, d (x ₀, y ₀) represent center of deformation point (x ₀, y ₀) deflection at place, L (x, y) represents that point (x, y) is to center of deformation point (x ₀, y ₀) distance, k represents the attenuation coefficient of tangential deformation, and the value of k is relevant with the rigidity of object, and rigidity is larger, and k value is larger, and body surface deformed region is less, and D represents body surface deformed region, and the deformation of body amount exceeding deformed region D is ignored.Being out of shape rendering effect intuitively for realizing flexible article, usually making the area of deformed region be greater than the contact area of finger and mobile terminal touch screen.

Below for the haptic feedback of virtual textile, the concrete implementation step of the method is described.

Step 1), demarcate the active pressing force of finger on mobile terminal touch screen and the relation curve of contact area:

The mobile terminal that this example adopts is the Samsung panel computer T310 having carried Android 4.2 system, first, build software platform, and at panel computer back, three pressure transducers are installed, the installation site distribution triangular in shape of pressure transducer, the panel computer having installed sensor is made to be placed in horizontal table top reposefully, like this, when finger tip pressing panel computer screen, can obtain finger presses size and active pressing force size, initiatively pressing force size equals the force value sum that three pressure transducers collect simultaneously.

Under original state, when finger contact mobile terminal screen, the active pressing force size F of finger tip ₀=3.07N, the contact area size S of finger tip and screen ₀=9.43.Then collection finger tip and screen contact area S are along with active pressing force F _pslow increase and the area value that changes, the relation curve of the finger being illustrated in figure 3 demarcation initiatively pressing force and contact area, the relational expression of matched curve is the max-thresholds of setting staff active pressing force is F _{p max}=5N, the initiatively computing formula of pressing force and contact area $F_p=\left\{\begin{array}{cc}3.08e^{3.3\&times;{10}^{-3}S}-3.07& ,F_p<5N\\ 5& ,F_p\&GreaterEqual;5N\end{array}\right..$

Step 2) according to finger tip initiatively pressing force size, calculate the size of mobile terminal haptic response power:

This example adopts gently little sense of touch finger ring as haptic device device, this sense of touch finger ring draught line is enclosed within finger tip (finger ring position is not overlapping with finger contact screen position), produce normal force by the minitype motor driving draught line being fixed on finger tip back, the normal force maximal value of generation is F _omax=3.3N.When point (640,250) on finger tip pressing touch-screen, during contact area S=200 with screen, utilize step 1) in the relation of the finger tip set up initiatively pressing force and contact area, obtain the active pressing force size of staff in real time now, haptic response power size $F_o=\frac{F_{o\max }\&times;F_p}{F_{p\max }}=\frac{3.3\&times;2.89}{5}=1.91N.$

Step 3) calculate dummy object be pressed acting force time the size of surface deformation amount and distribution:

This example is with normal deformation coefficient k _nthe virtual textile of=0.5mm/N is example, and when object is subject to finger tip active pressing force effect, the normal direction relative displacement of textile center of deformation point is appoint get 1 M in deformed region, this point to the distance L=1.5mm of center of deformation point, tangential deformation coefficient k _s=0.5mm/N, the deformation quantity at this some place: $d_M=d(x_0,y_0)\&times;e^{-k_s\&times;L}=5.78\&times;e^{-0.5\&times;1.5}=2.73\mathrm{mm}.$

Claims (4)

1. one kind is applied to touch feeling model building and the expression of the flexible article of mobile terminal, it is characterized in that, utilize finger tip and mobile terminal screen contact area, calculate the size of initiatively pressing force, then calculate haptic response and the dummy object surface deformation amount of flexible article, performing step comprises following three steps:

Step 1) based on mobile terminal system platform, obtain the contact area of staff finger tip and touch-screen, calibrate the computing formula of finger active pressing force and finger tip contact area;

Step 2) utilize 1) the middle computing formula set up, according to the contact area size detected in real time, calculate and point initiatively pressing force size, and then calculate finger and the haptic response in touch screen interaction process;

Step 3) according to the stiffness coefficient pointing initiatively pressing force size and dummy object, calculate the deflection on dummy object surface.

2. touch feeling model building and the expression being applied to the flexible article of mobile terminal according to claim 1, it is characterized in that, utilize mobile-terminal platform, the contact area of Real-time Obtaining finger and mobile terminal touch screen, calibrate the computing formula of finger active pressing force and finger tip contact area, its calibration process is as follows:

First, pressure transducer is arranged on the behind of mobile terminal, gathers staff initiatively pressing force size, meanwhile, call the function that mobile terminal system carries, finger and the contact area of touch-screen are equivalent to an ellipse, detect transverse and minor axis size, and then calculate ellipse area; Under original state, when finger contact mobile terminal screen, the force value of pressure transducer collection is F ₀, the contact area size of finger tip and screen is S ₀, wherein F ₀the pressure produced when comprising own wt and the finger tip nature contact screen of mobile terminal.When the contact area of finger tip and touch-screen changes, the active pressing force size of finger calculates according to formula (1):

$F_p=\left\{\begin{array}{c}f\left(S_t\right)-F_0,F_p<F_{p\max }\\ f\left(S_{\max }\right)-F_0,F_p\&GreaterEqual;F_{p\max }\end{array}\right.$ Formula (1)

In formula (1), F _prepresent the size of the active pressing force of finger, f is the fitting function according to measuring force value and the contact area obtained, f (S _t) represent when finger tip and mobile terminal screen contact area are S _ttime finger initiatively pressing force size, S _maxrepresent the Maximum Contact area of finger tip and screen, after the active pressing force of finger is increased to certain value, initiatively the increase of pressing force does not have a great impact finger contact screen area, so setting acting force threshold value F _pmax, when finger active pressing force is greater than F _pmaxtime, F _pconstant, and the acting force of finger tip when reality pressing screen generally can not be greater than F _pmax.

3. touch feeling model building and the expression being applied to the flexible article of mobile terminal according to claim 1, is characterized in that, utilize step 1) the middle computing formula set up, calculate the size of finger active pressing force, and then calculating mobile terminal haptic response; When staff is when pressing object, the power that the active pressing force of finger tip and object feed back to finger tip is the relation of acting force and reacting force, and namely the equal and opposite in direction of pressing force and feedback force, direction are contrary; And when being applied on mobile terminals by pressing force, due to the maximum holding capacity of touch-screen and the restriction of haptic feedback devices power output, the size of actual tactile feedback force is proportional to initiatively pressing force, but not equal initiatively pressing force; Therefore, mobile terminal haptic response power size calculates according to formula (2):

$F_o=\frac{F_{o\max }\&times;F_p}{F_{p\max }}---\left(2\right)$

In formula (2), F _orepresent mobile terminal haptic response power size, F _prepresent finger initiatively pressing force size, F _pmaxrepresent the maximal value of initiatively pressing force, F _omaxrepresent the maximum force that haptic feedback devices can produce.

4. touch feeling model building and the expression being applied to the flexible article of mobile terminal according to claim 1, is characterized in that, calculates the deflection on dummy object surface according to finger active pressing force size; Due to when staff and dummy object mutual time, the consistance of sensation only need be reached depending on/tactile sense reproduction process, namely close in the variation tendency of sensuously seen distortion and the power experienced and true environment, and without the need to numerically completely the same, therefore deflection adopts the computing method that Function Fitting is similar to; When staff is on the touchscreen without relative sliding, dummy object produces distortion, the normal direction relative displacement of center of deformation point under staff initiatively pressing force effect, and namely object is at the deformation quantity of center of deformation point, calculates according to formula (3):

$d(x_0,y_0)=\frac{F_p}{k_n}$ Formula (3)

In formula (3), d (x ₀, y ₀) represent body surface center of deformation (x ₀, y ₀) deflection at some place, F _prepresent at (x ₀, y ₀) some place finger initiatively pressing force size, F _psize according to formula (1) calculate, k _nrepresentation is to deformation coefficient, relevant to the stiffness coefficient of object, k _nbe worth larger, under the effect of formed objects power, the deflection of generation is less;

For isotropic object, according to distributed spring-mass model, when being subject to normal force effect, acting force can be delivered to each particle of adjacent area by action center by central spring, cause adjacent particle generation relative displacement, namely in the region that deformation occurs, equal with the deformation quantity that the point on the equidistant concentric circles of center of deformation point produces; Due to the restriction of mobile terminal computing power, in conjunction with early-stage Study, the deformation quantity of each point in terminal deformed region and the distance relation from center of deformation point are equivalent to exponential function.The deformation quantity of body surface each point, calculates according to formula (4):

$d(x,y)=\left\{\begin{array}{c}d(x_0,y_0)\&times;e^{-k\&times;L(x,y)},(x,y)\&Element;D\\ 0,(x,y)\&NotElement;D\end{array}\right.$ Formula (4)

In formula (4), d (x, y) represents the deformation quantity of point (x, y) in deformed region, d (x ₀, y ₀) represent center of deformation point (x ₀, y ₀) deflection at place, L (x, y) represents that point (x, y) is to center of deformation point (x ₀, y ₀) distance, k represents the attenuation coefficient of tangential deformation, and the value of k is relevant with the rigidity of object, and rigidity is larger, and k value is larger, and body surface deformed region is less, and D represents body surface deformed region, and the deformation of body amount exceeding deformed region D is ignored.Being out of shape rendering effect intuitively for realizing flexible article, usually making the area of deformed region be greater than the contact area of finger and mobile terminal touch screen.