JP3722992B2 - Object contact feeling simulation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an object contact feeling simulation apparatus, and more particularly to a simulation apparatus that allows a user to experience a feeling of hardness when touching an object surface.
[0002]
[Prior art]
Computer-based simulations have been adopted in various fields, and in recent years, the simulation of displaying a virtual reality world called a so-called virtual reality on a display screen by improving the computer's image processing function. Devices are becoming popular. In this type of simulation apparatus, the operator can usually move freely in a virtual space, and the display screen of the display is redrawn in real time as the operator moves.
[0003]
[Problems to be solved by the invention]
However, the conventional simulation apparatus focuses on presenting the virtual world through the operator's vision using the image on the display, etc., and lacks the function of presenting the virtual world through the operator's sense of touch. . However, in the future, it is expected that there will be a demand for a simulation device that can provide a pseudo-feel such as hardness or softness when touching the surface of an object. An inexpensive simulation apparatus using a computer is desired.
[0004]
Therefore, an object of the present invention is to provide a simulation apparatus that allows a user to experience a feeling of contact with an object surface in a pseudo manner.
[0005]
[Means for Solving the Problems]
  (1) According to a first aspect of the present invention, there is provided an object contact sensation simulation apparatus that performs a simulation for defining a predetermined virtual object and causing the user to experience the contact feeling with the virtual object in a simulated manner.
  Object information setting means for setting information for defining a virtual object;
  An action part having an action point movable in an arbitrary three-dimensional direction based on a force applied by an operator, a position detection part for detecting the position of the action point on the three-dimensional coordinate system, and given force control A force transducer that generates a force applied to the point of action based on a vector;
Based on the position of the action point detected by the position detector and the information in the object information setting means, a force control vector indicating a control force to be applied to the action point is obtained, and control for giving the obtained force control vector to the force transducer is performed. Arithmetic control means to perform;
Provided,
In the calculation control means,
A mutual positional relationship recognition unit for recognizing a mutual positional relationship between the action point and the virtual object based on the position of the action point detected by the position detection unit and the position of the virtual object defined by the information in the object information setting unit; ,
A time measurement unit that measures the time from when the point of action is recognized as having reached the surface position of the virtual object by the mutual positional relationship recognition unit;
Reaction force for calculating the reaction force to be generated at the action point based on the internal stay time given as the measurement value of the time measurement unit when the action point is determined to be inside the virtual object by the mutual positional relationship recognition unit An arithmetic unit;
A force control vector computing unit for obtaining a force control vector indicating a control force to be applied to the action point based on the obtained reaction force;
  Is provided.
[0006]
  (2) According to a second aspect of the present invention, in the object touch simulation apparatus according to the first aspect described above,
  The reaction force calculator increases the amount of reaction force the longer the internal stay time is.An operation is performed.
[0007]
  (3) According to a third aspect of the present invention, in the object contact feeling simulation device according to the first or second aspect described above,
  Object information setting meansA predetermined function f (t) having time t as a variable is stored in the object information setting means as information for defining the surface state of the virtual object.Set,
  The reaction force calculation unitThe magnitude of the reaction force is determined based on a function value obtained by substituting the internal residence time t into the function f (t).
[0008]
  (4) According to a fourth aspect of the present invention, in the object touch simulation device according to the third aspect described above,
  Object information setting meansAs information for defining a virtual object, a parameter K indicating the hardness of the virtual object is used.Set,
  The reaction force calculation unitThe magnitude of the reaction force is determined based on the product K · f (t) of the function value f (t) and the parameter K.
[0009]
  (5) According to a fifth aspect of the present invention, in the object contact feeling simulation device according to the fourth aspect described above,
  Object information setting meansAs the information for defining the virtual object, set the shape data that represents the surface of the virtual object as an aggregate of two-dimensional polygons,
  Force control vector calculation unitWhen the action point P is located inside the virtual object, a normal vector N perpendicular to the two-dimensional polygon α closest to the action point P is obtained, and this normal vector N is determined as a unit vector.And the force control vector is a vector having a magnitude corresponding to the reaction force calculated by the reaction force calculation unit.It is what I did.
[0010]
  (6) According to a sixth aspect of the present invention, in the object touch simulation device according to the first to fifth aspects described above,
  The reaction force calculation unitA function of calculating a first reaction force determined based on an internal stay time of the action point and a second reaction force determined based on a distance between the surface of the virtual object and the action point; Force of force and second reaction forceIs the reaction force to be generated at the point of actionIt is what I did.
[0011]
  (7) According to a seventh aspect of the present invention, in the object touch simulation device according to the sixth aspect described above,
  The reaction force calculation unitThe greater the distance d between the surface of the virtual object and the point of action, the greaterSecond reaction force increasesAn operation is performed.
[0012]
  (8) According to an eighth aspect of the present invention, in the object touch simulation device according to the seventh aspect described above,
  Object information setting meansAs information for defining a virtual object, a parameter k indicating the hardness of the virtual object is set.Set,
  The reaction force calculation unitThe magnitude of the second reaction force is determined based on the product (k · d) of the parameter k and the distance d.
[0013]
  (9) A ninth aspect of the present invention is the object contact feeling simulation device according to the first to eighth aspects described above.
  A display for displaying virtual objects;
  Object shape drawing that draws the shape and action point of the virtual object at a predetermined display position on the display screen based on the information set in the object information setting means and the action point position information detected by the position detector Means,
  Is further provided so that the shape and position of the virtual object and the position of the action point can be presented to the operator.
[0014]
  (10) According to a tenth aspect of the present invention, in the object touch simulation apparatus according to the ninth aspect described above,
  Object information setting meansAs information for defining a virtual object, texture data indicating the surface texture of the virtual object and light source data indicating the nature of the light source for illuminating the virtual object are further included.Set,
  The object shape drawing means draws the shape of the virtual object in consideration of the texture data and the light source data.
[0015]
(11) According to an eleventh aspect of the present invention, a program for causing a computer to operate as the object contact feeling simulation apparatus according to the first to tenth aspects is recorded on a computer-readable recording medium. It is a thing.
[0016]
  (12) In a twelfth aspect of the present invention, in the object contact feeling simulation device according to the first to tenth aspects described above,
  A finger sack that allows the action part of the force transducer to be fixed to the operator's fingertipConfiguredIs.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
§1. Basic configuration of the device
Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a block diagram showing a basic configuration of an object contact feeling simulation apparatus according to an embodiment of the present invention. In this apparatus, a predetermined virtual object can be defined, and a simulation can be performed so as to simulate a feeling of contact with the virtual object. The components of this apparatus are an object information setting means 10, a display 20, an object shape drawing means 30, an operation control means 40, and a force transducer 50 as shown in the figure.
[0018]
The object information setting means 10 has a function of setting information for defining a virtual object. When the operator inputs information such as data and parameters to the object information setting means 10, the input information is stored and held in the object information setting means 10. The operator can appropriately change the simulation condition setting by changing the data and parameters set for the object information setting means 10. In this embodiment, as information for defining a virtual object, as shown in the figure, three types of data such as shape data, texture data, and light source data, a predetermined function f (t) having a time t as a variable, A parameter K indicating the hardness of the virtual object can be set.
[0019]
The display 20 is a means for displaying a virtual object, and FIG. 1 shows a state in which a cubic virtual object B is displayed at a predetermined position. The object shape drawing unit 30 has a function of drawing the shape of the virtual object B at a predetermined position on the screen of the display 20 based on information (shape data, texture data, light source data) set in the object information setting unit 10. Have Note that the object shape drawing means 30 has a function of drawing not only the virtual object B but also the position of an action point P described later on the screen of the display 20. Displays the position of the action point P together with the virtual object B.
[0020]
The force transducer 50 includes an action unit 51, a position detection unit 52, and a force generation unit 53, and is connected to the calculation control unit 40. The force transducer 50 functions as a man-machine interface for the operator, and inputs an operation amount given from the operator and returns a force to the operator. In this embodiment, the force transducer 50 will function as a single finger, and a sense of contact with the virtual object will be experienced via this finger.
[0021]
An action point P is defined on the action part 51, and the action point P can be moved in a three-dimensional arbitrary direction based on a force applied by an operator. The action point P displayed on the display 20 in FIG. 1 is the position of the action point on the action part 51. The position detection unit 52 has a function of detecting the position of the action point P on the action unit 51 on the three-dimensional coordinate system. Specifically, the position of the action point P is detected as three coordinate values of x coordinate, y coordinate, and z coordinate. Here, the position of the action point P indicated by these three coordinate values is represented by data P (x, y, z).
[0022]
Data P (x, y, z) indicating the position of the action point is given to the calculation control means 40 and further given to the object shape drawing means 30. As described above, the object shape drawing means 30 draws the position of the action point P on the screen of the display 20 based on the data indicating this position. On the other hand, the calculation control means 40 is based on the position of the action point P detected by the position detection unit 52 and the position of the virtual object defined by the information in the object information setting means 10. Are calculated, and a calculation is performed to obtain a reaction force (force returned from the virtual object side to the operator side) to be generated at the action point P according to the recognition result. Specific calculation contents performed here will be described in detail later. Thus, when the reaction force to be generated at the action point P is obtained, a force control vector C indicating the control force to be applied to the action point P is obtained based on this reaction force, and the data indicating the force control vector C is represented by force Is applied to the transducer 50. The force generator 53 in the force transducer 50 has a function of generating a force to be applied to the action point P based on a force control vector C given from the arithmetic control means 40.
[0023]
§2. Information set in the object information setting means
Next, specific information set in the object information setting unit 10 in the simulation apparatus shown in FIG. 1 will be described. As described above, in this embodiment, shape data, texture data, light source data, function f (t) of time t, and parameter K indicating hardness are set.
[0024]
The shape data is data for specifying the three-dimensional shape of the virtual object. Here, the surface of the virtual object is expressed as an aggregate of two-dimensional polygons, and the vertex table indicating the vertex coordinates of the two-dimensional polygons and the connection relationship between the vertices constituting each two-dimensional polygon are shown. The shape data is constituted by the surface table. For example, consider a case where a virtual object composed of a cube as shown in FIG. This cube can be expressed as an aggregate of six squares, and is composed of a total of eight vertices numbered 1 to 8 in the figure. The shape data for such a cube can be composed of a vertex table shown in FIG. 2 (b) and a surface table shown in FIG. 2 (c). The vertex table shown in FIG. 2A shows the position coordinates in the XYZ three-dimensional coordinate system for each of the eight vertices. In the illustrated example, the cube shown in FIG. 2A has a vertex 1 located at the origin of the coordinate system, the side along the vertex 1-2 is on the X axis, and the side along the vertex 1-4 is the Y axis. Above, a side along the vertex 1-5 is located on the Z axis, and the length of one side is 1. The vertex table in FIG. 2 (b) merely indicates the position coordinates of the eight vertices, and the shape of the virtual object is actually defined by the surface table in FIG. 2 (c). This surface table shows the vertex configuration of the six surfaces (1) to (6) constituting this cube. For example, the surface (1) is formed by connecting the vertices 1-2-6-5. It becomes the surface to be formed.
[0025]
As described above, by using the vertex table and the surface table, the surface of a virtual object having an arbitrary shape can be defined. In the example of FIG. 2, the surface of the virtual object is defined as an aggregate of rectangles, but any polygon such as a triangle or a hexagon may be used. In implementing the present invention, it is not always necessary to use a two-dimensional polygon for the shape definition of the virtual object. For example, if it is a sphere or a cone, it can be defined using an equation, and the shape data set in the object information setting means 10 is information that can define a shape regardless of a numerical value or an expression. Anything can be used. In the embodiment shown here, since the shape data includes information indicating coordinates (in the example of FIG. 2, each coordinate value in the vertex table), the shape data functions as information defining the position together with the shape. Of course, position data for indicating the position may be set separately from the shape data.
[0026]
The texture data set in the object information setting means 10 is data for indicating the texture of the surface of the virtual object defined by the shape data. Specifically, values such as environmental color, diffusion color, specular color, and specular coefficient for each surface constituting the virtual object (surfaces (1) to (6) in the example of FIG. 2) are set as the texture data. The The light source data is data indicating the properties of the light source for illuminating the virtual object. Data indicating the shape of the light source (point, line, surface), light source position, light source color, etc. is set as the light source data. The The texture data and the light source data are data used for displaying the defined virtual object on the screen of the display 20. The object shape drawing means 30 draws the shape of the virtual object B in consideration of the texture data and the light source data.
[0027]
On the other hand, the function f (t) of the time t and the parameter K indicating the hardness are information defining the surface state of the virtual object. Both the function f (t) and the parameter K are factors that affect the hardness or softness of the object surface, but the parameter K functions as a coefficient that determines the magnitude of the reaction force acting on the action point P. On the other hand, the function f (t) fulfills the function of determining the time change of the magnitude of the reaction force. These functions will be described later. Although it is possible to set different functions or parameter values for each surface of the virtual object, both the function f (t) and the parameter K can be set. In this embodiment, one function is used for one virtual object. Only one parameter K is set for f (t) only. Therefore, the touch feeling on any surface is the same for one virtual object, but since different functions f (t) and parameter K are set for different virtual objects, the touch feeling is different for each object. You can experience the difference. Of course, if these settings are changed for each surface of one virtual object, different touch feelings can be experienced for each surface even for the same virtual object.
[0028]
§3. Specific device configuration
The block diagram shown in FIG. 1 shows the apparatus according to the present invention as a set of functional elements for convenience of explanation, and shows each functional element as a block. In practice, this simulation apparatus uses a computer. Built. That is, the object information setting unit 10, the object shape drawing unit 30, and the calculation control unit 40 in the apparatus shown in FIG. 1 can be configured by incorporating a program for executing the above-described processes into a general-purpose computer. . For example, data and parameters can be set for the object information setting means 10 using a computer input device such as a keyboard and a mouse, and the set data and parameters are stored in a memory and various storage devices. become. The drawing function by the object shape drawing unit 30 and the calculation processing function by the calculation control unit 40 are realized by a program incorporated in a computer, and this program is recorded on a computer-readable recording medium. It is possible to distribute. The display 20 can be configured by a general display device for a computer.
[0029]
On the other hand, the force transducer 50 has a first function for converting the physical operation of the operator into digital data (data indicating the position of the action point) and digital data (data indicating the force control vector C) given from the arithmetic control means 40. ) Is a physical component that performs a second function that is converted into a physical force and provided to the operator. A finger is usually used for a contact operation with a general object. Therefore, in this embodiment, the action portion 51 of the force transducer 50 is constituted by a finger sack that can be fitted and fixed to the fingertip of the operator so that the above functions are executed effectively, and based on the movement of the operator's finger. The action point P can be moved, and the control force based on the force control vector C is transmitted to the operator's finger through the finger sack.
[0030]
FIG. 3 is a block diagram showing the function of the force transducer 50 configured using the action part 51 in the form of this finger sack. The action part 51 is made of a material having elasticity such as rubber, and the operator can attach and fix the action part 51 to the tip of the finger. In the example shown in the figure, an action point P is defined at the tip of the action part 51 (of course, the action point P may be defined in any part of the action part 51, but to improve operability. Then, it is preferable to define at the fingertip position). In the present invention, it is necessary to prepare at least one set of such force transducers.
[0031]
In this force transducer 50, the action part 51 needs to be supported in a movable state with a three-dimensional degree of freedom. That is, the action point P needs to be movable in any three-dimensional direction based on the force applied by the operator (of course, the movable space of the action point P is within a predetermined range. Can be limited). Therefore, the operator can move the fingertip in any direction in the three-dimensional space with the action unit 51 attached to the fingertip. As described above, the position detection unit 52 has a function of sequentially detecting the position of the action point P in the three-dimensional space as data including three coordinate values P (x, y, z) in real time. Yes. On the other hand, the force generator 53 generates a force F based on the force control vector C sequentially given in real time from the arithmetic control means 40 and performs a function of sequentially applying this force to the action point P. Here, the force F applied to the action point P is a force having the direction and magnitude of the force control vector C.
[0032]
Eventually, the operator can move the finger wearing the action part 51 in any direction, but conversely, the operator always receives the force F applied to the action point P at the fingertip and feels the reaction force from the object. (Of course, when F = 0, no reaction force is felt).
[0033]
FIG. 4 is a perspective view showing a specific configuration example of such a force transducer 50. In the figure, a state where the action part 51 (finger sack) of the force transducer 50 is attached to the index finger of the right hand is shown. An action point P is defined at the tip portion of the finger, and the operator can experience a feeling of contact with the virtual object while moving the action part 51 in an arbitrary direction. In the illustrated force transducer 50, the two functions described above are realized using a plurality of link mechanisms. That is, since the action part 51 is supported by a plurality of free arms, it can be freely moved in any three-dimensional direction within a certain range of space. In addition, a mechanism for detecting the rotational position of each free arm is provided, and the three-dimensional coordinate value P (x, y, z) of the action point P can be detected. Furthermore, motors for applying a force to each of the free arms are prepared. By driving these motors, an arbitrary direction and an arbitrary amount of force can be applied to the action point P.
[0034]
Since the force transducer using such a plurality of link mechanisms is already a known device, a detailed description of its structure and mechanism will be omitted. As a commercially available product, for example, a device sold by the US Sensable Device Inc. under the trade name “PHANToM” can be used. Eventually, the liquid contact feeling simulation apparatus according to the present invention can be realized by connecting a force transducer as shown in FIG. 4 to a general-purpose computer and incorporating a predetermined program into the computer.
[0035]
§4. Operation of arithmetic control means
Subsequently, a specific operation of the simulation apparatus according to the above-described embodiment, particularly a reaction force calculation processing operation performed in the calculation control means 40 will be described in detail. Assume that a virtual object B (α and β indicate the surface of the virtual object B) is present at a position as shown in FIG. 5 on the three-dimensional coordinate system. Of course, since this virtual object is not a real object, for example, when a force transducer 50 as shown in FIG. 4 is used, at any position in the three-dimensional space where the force transducer 50 is installed, The existence of a virtual object is only defined. Here, the operator wears a finger sack-like action part 51 as shown in FIG. 4 on the index finger, and the action point P defined at the tip of the action part 51 is set in the direction indicated by the arrow M in FIG. Suppose you move it. That is, the action point P moves along a locus of the points P1 → P2 → P3 → P4 → P5 → P6 shown in the figure. Since the virtual object B is not a real object, if no force control vector is given to the force transducer 50, the operator can freely move the action point as shown in FIG. .
[0036]
Such movement of the action point P is contradictory when the virtual object B is a real object. That is, the movement from the point P1 → P2 → P3 is possible even when the virtual object B is a real object, but the movement of the point P3 → P4 → P5 → P6 is performed when the fingertip is inside the object. As long as the object is invading and the object is not deformed, such a movement of the action point is practically impossible. Of course, assuming that the object undergoes elastic deformation or plastic deformation, and if the point of action enters the inside of the object, a method of correcting the shape of the object in real time accordingly, as shown in FIG. There is no practical contradiction in the movement of the action point. However, in order to correct the object shape in real time, an enormous amount of arithmetic processing is required. In particular, when an object is drawn on the display 20 in real time, a fairly high-performance computer is required. Therefore, in the present embodiment, the virtual object B is formed of a rigid body and is handled as a shape that does not change at all.
[0037]
When the virtual object B is treated as a rigid body in this way, the movement of the points P3 → P4 → P5 → P6 in FIG. 5 corresponds to the state where the fingertip is recessed in the rigid body, and thus the actual physical phenomenon is faithfully simulated. In the sense that it does However, since the main point of the present invention is to let the operator experience a sense of contact with an object, it is not always necessary to faithfully simulate actual physical phenomena. Therefore, in the present invention, as shown in FIG. 5, an event in which the action point P enters the inside of the virtual object B is also recognized. However, in order for the operator to feel a touch, it is necessary to return some reaction force to the action point P when the action point P enters the inside of the virtual object B. The inventor of the present application can effectively transmit the hardness or softness on the surface of the virtual object B to the operator if the magnitude of the reaction force is determined on the basis of the internal residence time of the action point. I found it possible.
[0038]
For example, in FIG. 5, when the action point P is at the position of the point P1 or the position of the point P2, the fingertip of the operator has not yet touched the virtual object B, so there is no need to return any reaction force. However, after the action point P reaches the position of the point P3 (position on the surface α of the virtual object B) and moves from the point P4 → P5 → P6, it is informed that the object has been touched. It is necessary to return some reaction force. Therefore, when the mutual positional relationship between the action point P and the virtual object B is recognized and it is determined that the action point P is inside the virtual object B, the action point P has reached the surface position of the virtual object B. Based on the internal residence time t from the time point to the present time point, a reaction force to be generated at the action point P is obtained by calculation, and a force control vector C indicating a control force to be applied to the action point P is obtained based on the reaction force. Thus, the control for giving the obtained force control vector C to the force transducer 50 is performed.
[0039]
In the example of FIG. 5, the time point when the action point reaches the position of the point P3 is the reference time 0, the time point when reaching the point P4 is the internal stay time t = t1, and the time point when reaching the point P5 is the internal stay time t = At time t2 when the point P6 is reached, the internal residence time t = t3. In this embodiment, the larger the internal stay time of the action point is, the greater the reaction force is obtained. Therefore, the magnitude of the reaction force increases with time. In order to define the magnitude of the reaction force, a predetermined function f (t) with time t as a variable may be used. As already described, this function f (t) can be set in the object information setting means 10. In other words, the function f (t) is information for defining the surface state of the virtual object B.
[0040]
FIG. 6 shows some specific examples of the function f (t). In any case, the function value f (t) increases with the increase of time t. FIG. 6A shows an example using a linear function, and in this case, using a predetermined coefficient A, it is expressed by a simple expression f (t) = A · t. FIG. 6B shows an example using a function that shows a rapid increase while the time t is small but gradually decreases the increase rate, and can provide a relatively hard contact feeling. On the other hand, FIG. 6 (c) is an example using a function in which the function value shows a slow increase as time t increases and the function value is saturated at the end. It is possible to give.
[0041]
In the present embodiment, the parameter K indicating the hardness is set together with the function f (t) in the object information setting means 10, and the magnitude of the reaction force is expressed by the function value f (t), the parameter K, and the like. Is determined based on the product K · f (t). For example, in the example shown in FIG. 5, since the internal stay time t = t1 when the action point P reaches the position of the point P4, the function obtained by substituting the internal stay time t1 into the function f (t). The magnitude of the reaction force is determined based on the value K · f (t1) obtained by multiplying the value f (t1) by the parameter K. Similarly, when the action point P reaches the position of the point P5, the magnitude of the reaction force is determined based on the value K · f (t2), and when the action point P reaches the position of the point P6, The magnitude of the reaction force is determined based on the value K · f (t3). While the function f (t) is a factor indicating a change with time, the parameter K is a factor that is multiplied as an absolute value. By using these two factors together, it is possible to set a surface state rich in variation. Become.
[0042]
The method for obtaining the magnitude of the reaction force has been described above, but the actual reaction force is given to the action point P by the force generation unit 53 as the force control vector C. Therefore, in the present embodiment, as the information for defining the virtual object B in the object information setting unit 10, shape data that represents the surface of the virtual object as an aggregate of two-dimensional polygons is set. When the action point P is located inside the virtual object B, a normal vector N perpendicular to the two-dimensional polygon closest to the action point P is obtained, and the magnitude K · f is determined using this normal vector N as a unit vector. The vector of (t) is set as the force control vector C.
[0043]
For example, in the case of the example shown in FIG. 7, the action point P is located inside the virtual object B. Here, the surface of the virtual object B is defined by a large number of two-dimensional polygons α, β,..., And a unit vector directed to the normal line set to the two-dimensional polygon α closest to the action point P is used as a modulus. The vector is a line vector N and faces the same direction as the normal vector N, and a vector having a magnitude of K · f (t) is used as the force control vector C. In other words, the force control vector C is given by C = K · f (t) · N using a normal vector N (unit vector). The calculation control means obtains such a force control vector C by calculation, and performs processing to be given to the force generation unit 53 in the force transducer 50. The force generation unit 53 causes a force corresponding to the magnitude of the force control vector C to act on the action point P of the action unit 51 in the direction of the force control vector C.
[0044]
Eventually, when the fingertip of the operator passes through the surface position of the virtual object and enters the inside, a reaction force having a magnitude determined according to the passage of time (internal stay time) is perpendicular to the surface of the virtual object. It will be added as a control force in the direction. The operator feels this control force as a resistance force from the object side, and recognizes the contact feeling on the object surface. Therefore, in the example shown in FIG. 5, the operator presses the reaction force pushed back in the direction opposite to the arrow M from the point when the fingertip reaches the position of the point P3 (more precisely, the reaction force pushed back vertically from the surface α). ), And as the fingertip moves from point P4 → P5 → P6, it can be felt that the magnitude of the reaction force gradually increases (a function that increases with t is used as function f (t)). If you have).
[0045]
As described above, when the method of obtaining the magnitude of the reaction force based on the internal stay time from the time when the action point reaches the surface position of the virtual object to the present time is taken, the calculation load of the calculation control means 40 is extremely reduced. The advantage that you can do it. That is, the calculation control means 40 does not need to perform any calculation regarding the reaction force when the action point is outside the virtual object, and when the action point is inside the virtual object, the operation staying time t at the action point. Is simply measured and C = K · f (t) · N is simply calculated.
[0046]
§5. Method for obtaining reaction force considering depth of action point
By the way, when the reaction force is obtained by the method of §4 described above, strictly speaking, a phenomenon that contradicts the actual contact feeling may occur. For example, in FIG. 5, it is assumed that after moving the action point along the arrow M from the point P1 to the point P6, this time, the action point is moved from the point P6 to the point P1 in the direction opposite to the arrow M. In this case, the internal stay time t always increases despite the point of action toward the shallow position on the surface of the object, so the reaction force continues to increase gradually (or is saturated to the maximum value). . Of course, once the action point reaches the position of the point P3, the reaction force does not act at all thereafter, but the magnitude of the reaction force is determined only by the internal stay time t regardless of the actual position of the action point. As a result, there is a possibility that a sense of incongruity may occur compared to the actual touch feeling. In FIG. 5, even when the fingertip is moved along the same arrow M, different touch feelings are obtained depending on the moving speed of the fingertip. Of course, even in the real world, when you touch slowly, when you touch quickly, the actual contact feeling will also be different, so it is not necessarily the case that different touch feelings are obtained depending on the moving speed of the fingertip. It does not contradict reality. However, in order to experience a more realistic contact feeling, it is preferable to obtain the reaction force in consideration of the depth of the action point as described below.
[0047]
For example, in the case of the example shown in FIG. 8, the depth d of the action point P (distance from the surface α of the virtual object B) is obtained, and this is distinguished from the parameter k indicating the hardness (here, the parameter K described above). Therefore, a reaction force having a magnitude of k · d is assumed. As the force control vector C, a vector represented by the equation C = (K · f (t) + k · d) · N is used. Here, K · f (t) of the first term on the right side indicates the magnitude of the first reaction force determined based on the internal stay time t of the action point P as described in §4. The second term k · d indicates the magnitude of the second reaction force determined based on the distance d between the surface α of the virtual object B and the action point P as described above. Further, the normal vector N on the right side is a unit vector perpendicular to the two-dimensional polygon α closest to the action point P as described above. Eventually, a force control vector C indicating the control force to be applied to the action point P is obtained based on the combined force of the first reaction force and the second reaction force. It should be noted that when the resultant force is obtained, the product of the magnitudes of the first reaction force and the second reaction force is taken, and C = (K · f (t) × k · d) · N The force control vector C may be obtained.
[0048]
The second reaction force used here takes a larger value as the distance d between the surface of the virtual object and the action point becomes larger. Therefore, as the fingertip is inserted deeper into the interior from the surface of the virtual object, the second reaction force is used. The second reaction force is increased. In addition, since the magnitude of the second reaction force is determined based on the product (k · d) of the parameter k indicating the hardness of the virtual object and the distance d, the setting information of the hardness of the object is obtained. It can be reflected.
[0049]
As mentioned above, although this invention was demonstrated based on embodiment shown in figure, this invention is not limited to these embodiment, In addition, it can implement in a various aspect.
[0050]
For example, in the above-described example, only one set of force transducers 50 is used. However, if a plurality of sets of force transducers 50 are prepared, it is possible to experience a gripping operation on a virtual object. FIG. 9 shows a state where two sets of force transducers 50 are used and both action portions 51 (finger sack) are respectively attached to the thumb and index finger. In any case, the action point P is defined at the tip of the finger, and the operator can experience the action of gripping the virtual object B while moving both action parts 51 in any direction.
[0051]
In the above-described embodiment, the function f (t) uses a type of function whose function value increases as the time t increases. However, a special touch feeling (for example, a strange material that does not exist in reality). It is also possible to use a function of a type in which the function value decreases as the time t increases.
[0052]
【The invention's effect】
As described above, according to the object touch sensation simulation apparatus according to the present invention, since the magnitude of the reaction force is determined based on the internal stay time of the action point, it is possible to simulate a touch feeling on the object surface. It is possible to provide a simulation apparatus capable of
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of an object contact feeling simulation apparatus according to an embodiment of the present invention.
2 is a diagram showing an example of a virtual object and its shape data defined in the simulation apparatus shown in FIG. 1; FIG.
FIG. 3 is a block diagram showing functions of a force transducer in the simulation apparatus shown in FIG.
4 is a perspective view showing a specific configuration example of the force transducer shown in FIG. 3; FIG.
FIG. 5 is a side sectional view of an object for explaining a basic concept of how to obtain a reaction force in the present invention.
FIG. 6 is a graph showing a specific example of a function f (t) of time t used for obtaining a reaction force in the present invention.
FIG. 7 is a side sectional view of an object for explaining the basic concept of the direction of reaction force in the present invention.
FIG. 8 is a side sectional view of an object for explaining a basic concept using two kinds of reaction forces in the present invention.
FIG. 9 is a perspective view showing a specific configuration example of the present invention using two sets of force transducers.
[Explanation of symbols]
1-8 ... vertices
10: Object information setting means
20 ... Display
30 ... Object shape drawing means
40. Calculation control means
50 ... Force transducer
51. Action part
52 ... Position detection unit
53 ... Force generator
B ... Virtual object
C: Force control vector
d: Distance between the point of action and the surface of the virtual object
f (t) ... function of time t
F ... Force applied to the point of action
K, k ... Parameters indicating hardness
M: Direction of movement of action point
N ... Normal vector
P: Action point
P1 to P6 ... position of the action point P
P (x, y, z) ... position of the action point P
α, β: Polygons that make up the surface of a virtual object

Claims (12)

A device that defines a predetermined virtual object and performs a simulation to simulate a sense of contact with the virtual object,
Object information setting means for setting information for defining a virtual object;
An action part having an action point movable in an arbitrary three-dimensional direction based on a force applied by an operator, a position detection part for detecting the position of the action point on a three-dimensional coordinate system, and the given force A force generation unit that generates a force to be applied to the action point based on a control vector;
Based on the position of the action point detected by the position detector and the information in the object information setting means, a force control vector indicating a control force to be applied to the action point is obtained, and the obtained force control vector is obtained as the force transducer. Arithmetic control means for performing control given to
With
The arithmetic control means is
Reciprocal relationship recognition for recognizing the mutual positional relationship between the action point and the virtual object based on the position of the action point detected by the position detection unit and the position of the virtual object defined by the information in the object information setting means And
A time measuring unit that measures the time from when the action point is recognized as having reached the surface position of the virtual object by the mutual positional relationship recognition unit to the present time;
When the action point is determined to be inside the virtual object by the mutual positional relationship recognition unit, the reaction force to be generated at the action point is calculated based on the internal stay time given as the measurement value of the time measurement unit. The desired reaction force calculator,
A force control vector computing unit for obtaining a force control vector indicating a control force to be applied to the action point based on the reaction force;
An apparatus for simulating contact feeling of an object, comprising: The simulation apparatus according to claim 1,
An apparatus for simulating the contact feeling of an object, characterized in that the reaction force calculation unit performs a calculation in which the magnitude of the reaction force increases as the internal residence time becomes longer . The simulation apparatus according to claim 1 or 2,
The object information setting means sets a predetermined function f (t) with time t as a variable as information for defining the surface state of the virtual object ,
An object contact feeling simulation device , wherein the reaction force calculation unit determines the magnitude of the reaction force based on a function value obtained by substituting the internal stay time t into the function f (t). The simulation apparatus according to claim 3,
The object information setting means sets a parameter K indicating the hardness of the virtual object as information for defining the virtual object ,
Reaction force calculation unit, the magnitude of the reaction force, the function value f (t) and the contact feeling simulation apparatus of an object and determining based on the product K · f (t) with the parameters K. The simulation apparatus according to claim 4,
The object information setting means sets shape data representing the surface of the virtual object as an aggregate of two-dimensional polygons as information for defining the virtual object,
When the action point P is located inside the virtual object , the force control vector calculation unit obtains a normal vector N perpendicular to the two-dimensional polygon α closest to the action point P, and the normal vector N An object contact feeling simulation apparatus, characterized in that a vector having a magnitude corresponding to a reaction force calculated by a reaction force calculation unit is used as a force control vector . In the simulation apparatus in any one of Claims 1-5,
The reaction force calculation unit has a function of calculating a first reaction force determined based on the internal stay time of the action point and a second reaction force determined based on the distance between the surface of the virtual object and the action point. An object contact sensation simulation apparatus characterized in that a combined force of the first reaction force and the second reaction force is a reaction force to be generated at an action point . The simulation apparatus according to claim 6,
The object contact feeling simulation device, wherein the reaction force calculation unit performs a calculation in which the second reaction force increases as the distance d between the surface of the virtual object and the action point increases. The simulation apparatus according to claim 7, wherein
Object information setting means, as information for defining a virtual object, and set the parameter k indicating the hardness of the virtual object,
Reaction force calculation unit, the size of the second reaction force, contact sensation simulation apparatus of an object and determining based on a product (k · d) between the parameter k and the distance d. In the simulation apparatus according to any one of claims 1 to 8,
A display for displaying virtual objects;
Based on the information set in the object information setting means and the information on the position of the action point detected by the position detector, the shape of the virtual object and the object shape that draws the action point at a predetermined display position on the screen of the display Drawing means;
An apparatus for simulating contact feeling of an object , further comprising: The simulation apparatus according to claim 9, wherein
Object information setting means, as information for defining the virtual objects, further sets the light source data indicating a source properties for illuminating the texture data and the virtual object showing the surface texture of the virtual object,
The object shape drawing means draws the shape of a virtual object in consideration of the texture data and the light source data.   A computer-readable recording medium storing a program for causing a computer to function as arithmetic control means in the simulation apparatus according to claim 1. In the simulation apparatus in any one of Claims 1-10,
An object touch sensation simulation apparatus characterized in that the action portion of the force transducer is configured by a finger sack that can be fixed by being fitted to an operator's fingertip.

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