JP2007316936A - Tactile interface and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tactile interface capable of responding to a number of tools in itself. <P>SOLUTION: Many kinds of tool devices differed in operation mode are prepared, and the tactile interface is configured so that a plurality of joint balls provided on each tool device can be detachably connected to ball bearings at the tip of a plurality of tactile fingers 21-25 provided on a tactile finger base 20 which is spatially moved by an arm mechanism. Consequently, the tool device used for operations of the tactile interface can be easily replaced as occasion demands. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a haptic interface and a control method thereof.

  The tactile interface is an input / output device that generates force sensation in response to input and performs force feedback. For example, the tactile interface is used for work in a virtual reality space or remote operation of a robot or the like. By using such a tactile interface, it is possible to present to the operator a feeling of weight of the operation object that is physically isolated in reality or a feeling of resistance to the operation. In addition, a tactile interface capable of presenting the shape and texture of an object touched by an operation target through fine control of the generated force sense has been put into practical use.

Conventionally, as such a tactile interface, a multi-finger type tactile interface as described in Patent Document 1 has been proposed. This multi-finger type tactile interface has a structure in which five tactile fingers are arranged on a tactile finger base that is spatially moved by an arm mechanism. Each tactile finger is provided with a finger folder at the tip for holding the fingertip of the operator, and a sensor for detecting the movement of the fingertip is incorporated. Then, by performing force control of the tactile finger in conjunction with the detected movement of the fingertip, the force sense can be presented to the operator's fingertip. Further, in the multi-finger type haptic interface described in the same document, the position and posture of the arm are controlled so that the tactile finger base faces the fingertip of the operator held by each tactile finger. In particular,
(1) arranging the tactile finger base so that the operator's hand and the tactile finger base are plane-symmetric with respect to a plane formed by each fingertip of the operator;
(2) The tactile finger base is arranged so that the fingertips of the operator's finger and the tactile finger of the tactile interface are geometrically opposed to each other in the order of the middle finger, the thumb, and the pointing finger.
(3) arranging the tactile finger base so that the operability of the tactile finger is maximized;
Control of the position and posture of the arm is realized by any one of these three methods.
JP2003-300188A

  Recently, the use of such a tactile interface for medical and precision work training using virtual reality technology has been studied, and technical development for that purpose is being promoted. In order to bring such training in virtual reality closer to the actual one, it is desirable that the shape and operation mode of the operation unit and the tool actually used in the medical or precision work site are the same. For this reason, various tactile interfaces have been proposed in which an operation unit is formed in a shape and operation mode adapted to various tools.

  However, medical and precision work is more often performed by replacing various tools with different shapes and operation modes according to the situation, rather than working with only a single tool. Due to differences in the shape of the operation unit, the number of operation input points and their positional relationship, the generation of force senses required for presentation, and the like, the functions required for the tactile interface differ depending on the type of tool. Therefore, when performing training using a large number of tools, tactile interfaces corresponding to the number of tools must be prepared, the training system is expensive, and a large installation space is required.

  On the other hand, as shown in FIG. 11, when the object O is grasped and lifted by using a finger, a straight line L is axially centered on the object O by gravity G due to a shift between the support point and the center of gravity of the object O. Rotational moment M is generated. Then, the rotational moment is transmitted to the fingertip through friction with the surface of the object O. However, a tactile interface that can present the pressing force and frictional force when gripping an object has been practically used in the past, but there has not yet been proposed that it can present even the rotational moment transmitted to the fingertip. It is.

  Furthermore, there are the following problems regarding the control of the arm position and posture of the conventional multi-finger type haptic interface described above. As described above, in the conventional multi-finger type haptic interface, the position and posture of the arm are controlled so that the haptic base of the haptic interface is always arranged facing the fingertip of the operator. In such a case, even if the operation performed by the operator is slight, it may be necessary to move the arm greatly in order to maintain the positional relationship between the fingertip and the tactile base as described above. In this way, if the arm is moved disproportionately with respect to the magnitude of the operation performed, there is a risk that the operator may feel uneasy.

  The present invention has been made in view of the above circumstances, and a first problem to be solved is to provide a tactile interface capable of dealing with a large number of tools by itself. .

A second problem to be solved by the present invention is to propose a tactile interface capable of presenting a rotational moment transmitted to a fingertip when an object is gripped.
Furthermore, a third problem to be solved by the present invention is that a tactile sensation that can suppress the movement of an arm disproportionately large with respect to the magnitude of the performed operation while suitably ensuring the operation performance of the tactile finger. To provide an interface and a control method thereof.

  In order to solve the first problem, the invention described in claim 1 is a tactile finger base that is spatially moved by an arm mechanism, and is provided on the tactile finger base and used for an operation input and a force sense output, respectively. A tactile interface comprising a plurality of tactile fingers provided with a plurality of types of tool devices having different operation modes, and attachment tools that can be detachably connected to receiving portions respectively provided at the tips of the tactile fingers. Each device is provided.

  In the above configuration, the tactile finger connected to the tool device has a function of detecting an operation input and a function of outputting a force sense. Therefore, even if a sensor or an actuator is not provided on the tool device side, a force sense corresponding to the operation is provided. Can be presented. In addition, by changing the posture of a plurality of tactile fingers, the number and position of operation input points and force output points can be freely changed within a range allowed by the degree of freedom of each tactile finger. In addition, it is possible to flexibly cope with various device devices having different haptic generation modes. Therefore, the operation mode of the tactile interface can be easily changed to a mode corresponding to various types of tools only by preparing a tool device simulating the shape and mechanism of the required tool operation unit.

  In addition, if the receiving part provided in the tactile finger is connected to the attachment point of the tool device so as to be rotatable, the passive joint is connected to the connection part between the tactile finger and the tool device. Can be added, and the degree of freedom of the attachment mode of the tool device can be increased. In particular, if the mounting point and the receiving portion are configured to form a ball joint as described in claim 3, a passive joint having three degrees of freedom is added to the connecting portion between the tactile finger and the tool device. . Furthermore, in each tactile interface configured as described above, if the attachment point and the receiving portion are connected by magnetic force as described in claim 4, the tool device can be attached and detached easily and quickly. Will be able to.

  On the other hand, in order to solve the second problem, in the invention according to claim 5, in the haptic interface according to any one of claims 1 to 4, in the tool device, the operator may A rotary plate that is rotatably supported is provided at a portion where the fingertip comes into contact, and an actuator that applies rotational torque to the rotary plate is provided. In the invention described in claim 6, a tactile finger base that is spatially moved by an arm mechanism, a plurality of tactile fingers that are provided on the tactile finger base and are respectively used for operation input and force output, and the tactile sense A tactile interface comprising a finger folder provided at the tip of a finger and holding the fingertip of the operator, and abutting on the fingertip of the operator held inside the finger folder and rotatably supported A rotating plate and an actuator for generating a rotating torque applied to the rotating plate are provided.

  In each of the above configurations, when the rotational torque generated by the actuator is applied to the rotating plate, the rotational moment is transmitted to the fingertip of the operator who touched the rotating plate through friction with the rotating plate. Therefore, by controlling the actuator to generate a rotational torque as necessary, it is possible to present a rotational moment that is transmitted to the fingertip of the operator when an object is gripped.

  Furthermore, in order to solve the third problem, in the invention according to claim 7, in the haptic interface according to any one of claims 1 to 6, the arm mechanism is driven to a target position and posture. The index value of the degree of change in the joint angle of the arm mechanism for driving the arm mechanism from the current position and posture to the target position and posture is subtracted from the index value of the operability of the tactile finger when Control means for controlling the position and posture of the arm mechanism is provided so as to maximize the value. The invention according to claim 8 further includes a tactile finger base that is moved in space by an arm mechanism, and a plurality of tactile fingers that are provided on the tactile finger base and are used for operation input and force output, respectively. In the tactile interface, the arm mechanism is driven from the current position and posture to the target position and posture from the index value of the operability of the tactile finger when the arm mechanism is driven to the target position and posture. Therefore, control means for controlling the position and posture of the arm mechanism is provided so that the value obtained by subtracting the index value of the change amount of the joint angle of the arm mechanism for the purpose is maximized. Furthermore, in the invention described in claim 9, a tactile interface comprising: a tactile finger base that is moved in space by an arm mechanism; and a plurality of tactile fingers that are provided on the tactile finger base and are used for operation input and force sense, respectively. As a method of controlling the arm mechanism, the arm mechanism is moved from the current position and posture to the target position and posture from the index value of the operability of the tactile finger when the arm mechanism is driven to the target position and posture. The control target of the position and posture of the arm mechanism is calculated so that the value obtained by subtracting the index value of the change amount of the joint angle of the arm mechanism for driving the arm mechanism is maximized.

  According to these configurations and control methods, the control target is set so that the amount of change in the joint angle of the arm mechanism can be suppressed while maintaining high operability of the tactile finger. Therefore, while maintaining the operational performance of tactile fingers in a suitable state and enabling high-precision force sense presentation, changes in the position and posture of the arm mechanism do not become unduly large with respect to the size of the performed operation. Will be suppressed.

According to the tactile interface according to the first to fourth aspects of the present invention, it is possible to deal with a large number of tools using only a single tactile interface.
Further, according to the haptic interface according to claims 5 and 6 of the present invention, it is possible to present a rotational moment transmitted to the fingertip when an object is gripped.

  Furthermore, according to the tactile interface according to the seventh and eighth aspects of the present invention and the tactile interface control method according to the ninth aspect of the present invention, the magnitude of the operation performed while suitably ensuring the operation performance of the tactile finger. In contrast, the movement of the arm which is disproportionately large can be suppressed.

Hereinafter, an embodiment embodying a tactile sensation interface and a control method thereof according to the present invention will be described in detail with reference to FIGS. The tactile interface of this embodiment includes a 6-degree-of-freedom arm mechanism and five tactile fingers, and is configured to perform multipoint force sense presentation using these tactile fingers. And this tactile interface is largely
・ Various changes can be made to the operation mode with the exchangeable tool device.
-The ability to present a rotational (friction) moment that acts when an object is gripped to the operator's fingertips,
・ By controlling the position and posture of the arm mechanism in consideration of the increase in operability of the tactile fingers and the suppression of joint changes in the arm mechanism, it is possible to suppress arm movements that are disproportionately large with respect to the performed operation.
It has the following three features.

  Here, first, the configuration of the arm mechanism of the tactile interface of this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 shows a side structure of the haptic interface of the present embodiment, and FIG. 2 shows a link structure of arms of the haptic interface.

  As shown in FIG. 1, an arm base 11 is installed at the upper end of a support column 10 that serves as a base for a tactile interface. The arm mechanism 12 attached to the arm base 11 has two links of almost the same length, that is, an arm first link 13 and an arm second link 14 so as to have an appearance similar to that of a human arm. It is configured. The arm first link 13 is connected to the arm base 11 via the shoulder joint portion 15, and the arm first link 13 and the arm second link 14 are connected to each other via the elbow joint portion 16. Further, a tactile finger base 20 is connected to the tip of the arm second link 14 via a wrist joint portion 17. The tactile finger base 20 is provided with first to fifth tactile fingers 21 to 25 respectively corresponding to five fingers of a human hand.

  In the tactile interface of this embodiment, such an arm mechanism 12 is configured as a six-degree-of-freedom mechanism. Specifically, as shown in FIG. 2, two degrees of freedom are set for the shoulder joint portion 15, one degree of freedom for the elbow joint portion 16, and three degrees of freedom for the wrist joint portion 17. The arm first link 13 is allowed to be twisted (rotation direction Φ1) and bent back and forth (rotation direction Φ2) with respect to the arm base 11 by the shoulder joint portion 15. The arm second link 14 is allowed to bend back and forth (rotation direction Φ3) with respect to the arm first link 13 by the elbow joint portion 16. Further, the tactile finger base 20 is allowed to be twisted (rotation direction Φ4), bent back and forth (rotation direction Φ5), and inward and outward (rotation direction Φ6) with respect to the arm second link 13 by the wrist joint portion 17. . In addition, a servo motor and an encoder (not shown) are provided on each rotation shaft of each joint portion (15, 16, 17), and the drive of each rotation shaft and the detection of the rotation angle are performed individually. .

  Next, the configuration of the haptic fingers 21 to 25 installed on the haptic finger base 20 will be described with reference to FIG. 3 schematically showing the perspective structure of the first haptic finger 21. Each of the tactile fingers 21 to 25 has the same configuration. As shown in the figure, each tactile finger 21 to 25 has two links (first finger link 26 and second finger link 27). The finger first link 26 is connected to the tactile finger base 20 via a finger first joint portion 28 having two degrees of freedom that allows its forward and backward bending (rotation direction Φ6) and inward and outward rotation (rotation direction Φ7). . Further, the finger second link 27 is connected to the finger first joint portion 28 via a finger second joint portion 29 having one degree of freedom allowing its forward / backward bending (rotation direction Φ8). In the tactile fingers 21 to 25 as well, servo motors and encoders (not shown) are provided on the rotation shafts of the joints (28, 29), respectively, so that the rotation shafts are driven and the rotation angles are detected. It is done individually. In addition, a triaxial force sensor 30 is installed on the finger second link 27 of each tactile finger 21 to 25, and the forces applied to the tactile fingers 21 to 25 are orthogonal to each other. It is also detected in the three-axis direction.

  The arm mechanism 12 of the tactile interface and the rotation angles of the joints of the tactile fingers 21 to 25 and the detection signals of the forces applied to the tactile fingers 21 to 25 detected by the triaxial force sensor 30 are externally controlled. Input to the device 18. Based on these detection signals, the external control device 18 sets the positions and postures of the arm mechanism 12 and the tactile fingers 21 to 25 and the control targets of the generated force senses, and outputs control signals to the servo motors of the joints. Details of the control of the tactile interface by the external control device 18 will be described later.

<Replacement of tool device>
In the tactile interface of the present embodiment, a tool device used for operation by the operator is detachably connected to the tips of the tactile fingers 21 to 25. Multiple types of tool devices are prepared depending on the application, and can be easily replaced as necessary. In order to attach and detach such a tool device, a ball bearing 32 recessed in a hemispherical shape is formed at the tip of the finger second link 27 of each tactile finger 21 to 25, and a permanent magnet 31 is directly below the ball bearing 32. Built in. A joint ball 33 provided on the tool device is attached to such a ball bearing 32. The joint ball 33 is a sphere formed of a ferromagnetic material such as steel, and is attracted to the ball bearing 32 by the permanent magnet 31. A joint ball 33 is rotatably connected to the ball bearing 32, and the ball bearing 32 and the joint ball 33 form a passive ball joint having three degrees of freedom.

  Next, various tool devices prepared for the tactile interface will be described. This tactile interface provides four tool devices for reproducing the operation of three types of tools used in surgery and direct manipulation of objects by hand.

  FIG. 4 shows the general shape of a saddle-type tool device for reproducing the operation of a saddle-shaped tool used for applications such as cutting, sandwiching, and pushing-out. Various types of scissors-type tools are used in the field of surgery, but the basic operation mode is common, so the operation of various scissors-type surgical tools can be reproduced with a single tool device. .

  As shown in the figure, the scissors-type tool device 40 has two blades each having a blade portion 41 at one end and a grip portion 42 at the other end, similar to a general scissors. 44 and 45 are connected to each other so as to be rotatable around a fulcrum portion 43 provided in the intermediate portion. The saddle-shaped tool device 40 is provided with three joint balls 33 as described above. Specifically, the joint balls 33 are respectively installed on the fulcrum part 43 of the scissors-type tool device 40 and the two grip parts 42 as the action points.

  FIG. 5 shows an example of how the saddle-type tool device 40 is attached to the tactile fingers 21 to 25 of the tactile interface. In the example of the figure, the joint ball 33 of the fulcrum part 43 of the scissors-type tool device 40 is connected to the tip of the fourth tactile finger 24 corresponding to the ring finger, and corresponds to the first tactile finger 21 and the indicating finger corresponding to the thumb. The joint balls 33 of the grip portions 42 of the scissors-type tool device 40 are respectively connected to the tip of the second tactile finger 22 that performs the above operation. The remaining tactile fingers that are not used for connection, that is, the third tactile finger 23 and the fifth tactile finger 25 are retracted in a folded state at positions that do not interfere with the operation or operation of the saddle-type tool device 40. According to such an attachment mode, the force sense at the time of cutting the object by opening and closing the heel is controlled while supporting the three points of the heel tool device 40 and holding the posture, and the first and second tactile fingers 21 and 22 are controlled. Can be presented through. The force sense when an object touches the tip or side of the bag can be presented mainly by the control of the arm mechanism 12.

  Next, a cutting simulation using such a saddle type tool device 40 will be described. Here, the stress R (τ) corresponding to the resistance feeling at the time of cutting at the coordinate τ is calculated by the following equation (1).

上式（１）では、支点から作用点までの距離を「σ」、支点から鋏の握りまでの距離を「ψ」、粘性及び弾性を考慮した見かけの弾性係数を「Ｋ」、両刃の開閉角を「θ」、二枚の刃の間の間隔を「ｄ」、粘性係数を「γ」、支点を中心とした回転運動の角速度を「ω」でそれぞれ表している。また上式（１）において、「Ｔｓ＝ｔａｎ（θ／２）」である。こうした上式（１）を用いて、鋏の刃と切断対象の物体との接触範囲における座標τの応力Ｒ（τ）を求め、その応力Ｒ（τ）を接触範囲の長さで積分することで、操作者の手にフィードバックする抵抗力の大きさを求めることができる。

In the above equation (1), the distance from the fulcrum to the action point is “σ”, the distance from the fulcrum to the grip of the heel is “ψ”, the apparent elastic coefficient considering the viscosity and elasticity is “K”, and the opening and closing of the double-edged blade The angle is represented by “θ”, the interval between the two blades is represented by “d”, the viscosity coefficient is represented by “γ”, and the angular velocity of the rotational motion around the fulcrum is represented by “ω”. In the above equation (1), “Ts = tan (θ / 2)”. Using the above equation (1), the stress R (τ) of the coordinate τ in the contact range between the scissors blade and the object to be cut is obtained, and the stress R (τ) is integrated by the length of the contact range. Thus, the magnitude of the resistance force fed back to the operator's hand can be obtained.

  FIG. 6 shows a measurement result of the resistance force when the scissors-type tool device 40 is attached to the tactile interface of the present embodiment and the scissors are opened and closed every two seconds in a free space, that is, without a cutting target. . From this result, when opening and closing the saddle type device device 40 attached to the tactile interface, the resistance of the mechanism of the tactile interface is added, so that the resistance force is higher than when opening and closing the saddle type device device 40 alone. Was confirmed to be large. Therefore, when performing a cutting simulation, it is necessary to determine the magnitude of the force sense (resistance force) to be applied to the saddle tool device 40 in consideration of the resistance of the added mechanism.

  FIG. 7 shows an example of how the female tool device used to reproduce the operation of the surgical scalpel is attached to the tactile interface. In the figure, the state of the hand when operating the female tool device is also indicated by a one-dot chain line. The female tool device 50 imitating the shape of a surgical scalpel has three joint balls 33 installed at the tips of the first to third tactile fingers 21 to 23, respectively. It is connected. According to such an attachment aspect, the force sense at the time of cutting of the object by the scalpel can be presented through the control of the first to third tactile fingers 21 to 23. The movement of the female tool device 50 and the presentation of the sense of force when the female touches the surrounding object can be performed mainly through the control of the arm mechanism 12.

  FIG. 8 shows an example of how the syringe-type tool device is attached to the tactile interface used to reproduce the operation of the syringe. Also in the figure, the state of the hand during the operation of the syringe-type tool device is also shown by a one-dot chain line. The syringe-type tool device 60 is composed of two pearls, which are a cylinder part 61 and a piston part 62 inserted into the cylinder part 61 so as to be capable of reciprocating linearly. The joint balls 33 are provided at the tip of the cylinder part 61 and the end part of the piston part 62, respectively, and are connected to the first tactile finger 21 and the fifth tactile finger 25, respectively. These two joint balls 33 are both located on the central axis of the cylinder portion 61. The force sense accompanying the injection operation of the syringe by pushing the piston portion 62 can be presented by controlling the first tactile finger 21 and the fifth tactile finger 25. Further, the movement of the syringe-type tool device 60 and the presentation of the sense of force when the syringe contacts a surrounding object can be performed mainly through the control of the arm mechanism 12. In addition, in the attachment mode of the figure, since the syringe-type tool device 60 is only supported at two points at both ends thereof, the moment around the axis of the syringe cannot be presented. However, such moment can be presented if the number of connecting portions with the tactile fingers is increased by one more point at a position somewhat away from the central axis of the cylinder portion 61. However, since the presentation of such moments is almost unnecessary in training the operation of the syringe, here, such moments are intentionally ignored to simplify the configuration and control.

  Furthermore, the tactile interface of the present embodiment is also provided with a tool device for performing an operation of directly grasping or touching an object by hand. FIG. 9 shows an overview of the finger folder, which is a tool device used for such operations. The finger folder 70 includes a substantially bowl-shaped folder unit 71 into which an operator's fingertip is inserted and held. A joint ball 33 is fixed to the distal end portion of the folder portion 71, and is connected to the distal ends of the tactile fingers 21 to 25 via the joint ball 33 so as to be rotatable. Such a finger folder 70 is connected to each of the five tactile fingers 21 to 25 of the tactile interface. In this state, each of the tactile fingers 21 to 25 is added with 3 degrees of freedom by the joint ball 33 to 3 degrees of freedom by the finger first joint portion 28 and the second joint portion 29 which are active joints. Will be set. Thereby, the tactile fingers 21 to 25 can flexibly follow the movement of the operator's fingers. Since the finger folder 70 is only attracted by the magnetic force of the permanent magnet 31 built in the tactile fingers 21 to 25, an excessive force acts between the tactile fingers 21 to 25 and the fingertip of the operator. Sometimes, the finger folder 70 and the tactile fingers 21 to 25 are easily separated.

  As described above, in the tactile interface of this embodiment, various types of tool devices can be easily exchanged. In this tactile interface, the tactile fingers 21 to 25 to which the tool device is connected have a function of detecting an input operation force and a function of outputting a force sense, respectively. It is possible to present a sense of force according to the operation without providing a touch. In addition, by changing the postures of a plurality of (here, five) tactile fingers 21 to 25, it becomes possible to flexibly cope with various tool devices having different operation modes and required force generation modes. ing.

  When performing surgical training using virtual reality technology using such a tactile interface, the tactile sensation corresponds to the tools required for the progress of the operation in the virtual reality space displayed on the display etc. The tool devices connected to the fingers 21 to 25 can be exchanged sequentially. Therefore, training can be performed in a state closer to the actual situation. In addition, since the tool device is only attracted | sucked with the magnetic force of the permanent magnet 31 with respect to the tactile fingers 21-25, it can exchange very easily and rapidly.

  In the above, the case where various tool devices corresponding to surgical tools are provided has been described. However, if a tool device corresponding to a required tool is prepared, the tactile interface performs training other than surgical operations such as precision machining. Also available. By the way, the tool device does not need to have the entire shape and mechanism of the corresponding tool, but at least it should be formed in the same way as the shape and mechanism of the operation part of the tool, so that the operation feeling similar to that tool can be reproduced. Can do. For example, in the case of the saddle-type tool device 40, if the two grip portions 42 are connected to the fulcrum portion 43 so as to be opened and closed even if the portion closer to the cutting edge than the fulcrum portion 43 is omitted, It is possible to reproduce the operational feeling of various types of tools. However, if the tool device is formed to mimic the overall shape and function of the corresponding tool, the reproducibility of the tool can be enhanced visually.

In the tactile device of the present embodiment, the ball bearing 32 corresponds to the “receiving portion” and the joint ball 33 corresponds to the “mounting point”.
<Presentation of rotational (friction) moment accompanying object gripping>
Next, a configuration for realizing the presentation of the rotational (friction) moment acting on the fingertip when the object is held as described above will be described. Here, a case will be described in which a mechanism related to the presentation of the rotational moment is incorporated in the finger folder.

  FIG. 10 shows a cross-sectional structure of a finger folder with such a rotational moment presentation function. As shown in the figure, a disk-shaped rotary plate 76 is rotatably supported on a portion of the inner periphery of the folder portion 75 of the finger folder that comes into contact with the fingertip of the operator to be inserted. It is installed at. The rotating plate 76 is fixed to an output shaft of a motor 77 inserted and fixed inside a joint ball 78 attached to the folder portion 75 so as to be integrally rotatable.

  When an operating voltage is applied to the motor 77, the motor 77 generates rotational torque. At this time, if the rotating plate 76 is pressed with a certain amount of force by the fingertip of the operator, the rotation of the rotating plate 76 is limited, but the frictional moment corresponding to the rotational torque generated by the motor 77 is reduced. It is transmitted to the fingertip of the operator who touched 76. Here, this friction moment is presented as a rotational moment that is felt when the object is gripped as described above. That is, when the operator performs an operation of gripping an object in the virtual space, the motor 77 can be controlled as necessary to present the rotational moment to the fingertip of the operator. In the present embodiment, the motor 77 corresponds to “an actuator that applies rotational torque to the rotating plate”.

<Arm control considering suppression of inappropriate arm movement>
Next, the control of the position and posture of the arm for suppressing the movement of the arm disproportionately large with respect to the magnitude of the operation as described above will be described.

  The external controller 18 (see FIG. 1) of the haptic interface uses the force of each haptic finger 21 to 25 based on the detection result of the triaxial force sensor 30 of each haptic finger 21 to 25 and the simulation result of the virtual reality space. In addition to performing control, position / posture control of the arm mechanism 12 is performed based on the detection results of the joint angles of the arm mechanism 12 and the tactile fingers 21 to 25. In the present embodiment, the following evaluation function is used for the position / posture control of the arm mechanism 12 at this time. This evaluation function is given by the following equation (2).

上式（２）において「αi 」，「βi 」はそれぞれ第ｉ触覚指についての重み係数を示している。また「Ｗi 」は第ｉ触覚指の可操作性をそれぞれ示しており、同第ｉ触覚指の運動学ヤコビ行列を「Ｊi 」とすると、下式（３）で与えられる。下式（３）において「ｌi1」，「ｌi2」はそれぞれ、第ｉ触覚指の指第１リンク、及び指第２リンクの長さを、「ｑi2」，「ｑi3」はそれぞれ、同第ｉ触覚指の第２関節（回動方向Φ８）の角度，第３関節（回動方向Φ９）の角度を表している。

In the above equation (2), “αi” and “βi” indicate weighting factors for the i-th tactile finger, respectively. “Wi” indicates the operability of the i-th tactile finger. When the kinematic Jacobian matrix of the i-th tactile finger is “Ji”, it is given by the following equation (3). In the following formula (3), “li1” and “li2” are the lengths of the first and second finger links of the i-th tactile finger, respectively, and “qi2” and “qi3” are the i-th touch sensations, respectively. It represents the angle of the second joint (rotation direction Φ8) and the angle of the third joint (rotation direction Φ9) of the finger.

一方、上式（２）において「Ｐi 」は、第ｉ触覚指についてその各関節の回動角が稼動範囲内に収まるようにするために与えられるペナルティ関数で、下式（４）にて与えられる。下式（４）において「ａij」，「ｂij」は、第ｉ触覚指の第ｊ関節の左右の可動限界を、「ｋj 」は第ｊ関節の重み係数を、「ｌ」は指数関数の形状を調整する係数である。

On the other hand, in the above equation (2), “Pi” is a penalty function that is given so that the rotation angle of each joint of the i-th tactile finger is within the operating range, and is given by the following equation (4). It is done. In the following expression (4), “aij” and “bij” are the left and right movement limits of the j-th joint of the i-th tactile finger, “kj” is the weight coefficient of the j-th joint, and “l” is the shape of the exponential function Is a coefficient to adjust.

更に上式（２）において「Ｑa 」は、アーム機構１２の関節角度ベクトルｑa の変化量を評価する項であり、下式（５）にて与えられる。下式（５）での「ｑa0」は計算初期のアーム機構１２の関節角度ベクトルを、「Γ」は重み行列をそれぞれ表している。

Further, in the above equation (2), “Qa” is a term for evaluating the amount of change in the joint angle vector qa of the arm mechanism 12 and is given by the following equation (5). In the following equation (5), “qa0” represents the joint angle vector of the arm mechanism 12 at the initial stage of calculation, and “Γ” represents the weight matrix.

以上のような評価関数の右辺第１項の値は、アーム機構１２を目標とする位置及び姿勢に駆動したときの触覚指２１〜２５の可操作性の大きさの指標値となっている。また右辺第２項は、アーム機構１２を現状の位置及び姿勢から目標とする位置及び姿勢に駆動するためのアーム機構１２の関節角度の変化度合の指標値となっている。そして外部制御装置１８は、前者の指標値から後者の指標値を減算した評価関数の値ＰＩが最大となるように、最終的なアーム機構１２の位置及び姿勢の制御目標を算出するようにしている。

The value of the first term on the right side of the evaluation function as described above is an index value of the operability of the tactile fingers 21 to 25 when the arm mechanism 12 is driven to the target position and posture. The second term on the right side is an index value of the degree of change in the joint angle of the arm mechanism 12 for driving the arm mechanism 12 from the current position and posture to the target position and posture. Then, the external control device 18 calculates the final position and orientation control targets of the arm mechanism 12 so that the value PI of the evaluation function obtained by subtracting the latter index value from the former index value is maximized. Yes.

  According to such position / posture control of the arm mechanism 12, the joint angle of the arm mechanism 12 is maintained while maintaining the high operability of the tactile fingers 21 to 25 by keeping the rotation angle of each finger joint within the movable range. The control target is set so that the amount of change in the amount can be kept small. Therefore, the position and posture of the arm mechanism 12 are changed disproportionately with respect to the size of the operation while maintaining the operational performance of the tactile fingers 21 to 25 in a suitable state and enabling highly accurate force sense presentation. It is possible to prevent the operator from feeling uneasy.

According to the tactile interface and its control method of the present embodiment, the following effects can be obtained.
(1) Joints that can be detachably connected to the ball bearings 32 provided at the tips of the tactile fingers 21 to 25 while preparing a plurality of types of tool devices (40, 50, 60, 70) having different operation modes. A ball 33 is provided for each tool device. In such a tactile interface, the tactile fingers 21 to 25 have a function of detecting an operation input and a function of outputting a force sense. Therefore, even if a sensor or an actuator is not provided on the tool device side, a force sense corresponding to the operation is not provided. You can make a presentation. In addition, by changing the postures of the tactile fingers 21 to 25, the number of input points of operation and the output points of force senses and positional relationships can be freely changed within a range permitted by the degrees of freedom of the tactile fingers 21 to 25. Therefore, it is possible to flexibly cope with various tool devices having different operation modes and necessary force generation modes. For this reason, it is possible to easily change the operation mode of the tactile interface to a mode corresponding to various types of tools only by preparing a tool device imitating the shape and mechanism of the operation unit of the required tool.

  (2) Since a passive joint with 3 degrees of freedom is added to the connecting portion between the joint ball 33 of the tool device and the ball bearing 32 at the tip of the tactile fingers 21 to 25, the degree of freedom regarding the mounting manner of the tool device is increased. It is possible to use a wider variety of device devices.

(3) Since the tool device and the tactile fingers 21 to 25 are coupled by magnetic attraction, the tool device can be exchanged easily and quickly.
(4) Since the tool device and the tactile fingers 21 to 25 can be easily attached and detached, when an excessive force is applied between them, both of them can be easily separated, which is excessive for the tool device and the operator. Can be avoided.

  (5) A finger folder connected to the tip of each of the tactile fingers 21 to 25 as one of the tool devices, and is rotatably supported at a portion where the operator's fingertip comes into contact with the inner periphery of the finger folder. A rotating plate 76 is provided, and a motor 77 for applying a rotating torque to the rotating plate 76 is provided. In such a finger folder, when the rotational torque generated by the motor 77 is applied to the rotary plate 76, the rotational moment is transmitted to the operator's fingertip touching the rotary plate 76 through friction with the rotary plate 76. Therefore, by controlling the motor 77 and generating rotational torque as necessary, it is possible to present a rotational moment that is transmitted to the fingertip of the operator when an object is gripped.

  (6) From the index value of the operability of the tactile fingers 21 to 25 when the arm mechanism 12 is driven to the target position and posture, the arm mechanism 12 is set to the target position and the current position and posture. The position and posture of the arm mechanism 12 are controlled so that the value obtained by subtracting the index value of the degree of change in the joint angle of the arm mechanism 12 for driving to the posture is maximized. According to such a control mode, the control target is set so that the amount of change in the joint angle of the arm mechanism 12 can be kept small while maintaining high operability of the tactile fingers 21 to 25. Therefore, while maintaining the operation performance of the tactile fingers 21 to 25 in a suitable state and enabling high-precision force sense presentation, the change in the position and posture of the arm mechanism 12 with respect to the magnitude of the performed operation It can be suppressed so that it does not grow disproportionately.

(7) The multipoint force sense can be presented by the five tactile fingers 21 to 25.
(8) The arm mechanism 12 can freely move the haptic point (tactile finger base 20) in space.

(9) Since the arm mechanism 12 is configured as a six-degree-of-freedom mechanism, the tactile finger base 20 can be moved while flexibly following the movement of the operator's arm.
In addition, you may change the said embodiment as follows.

  In the above embodiment, the permanent magnet 31 for connecting the tactile fingers 21 to 25 and the tool device is provided on the tool device side, or is provided on both the tactile fingers 21 to 25 side and the tool device side. Or you can do it. Moreover, you may make it connect those using an electromagnet instead of a permanent magnet. Even in such a case, it is possible to easily and quickly attach and detach the tool device with the tactile interface of the above embodiment.

  The tactile fingers 21 to 25 and the tool device may be connected by means other than magnetic force such as fitting. Even in that case, the tool devices can be exchanged if they are detachably connected.

  The connecting portion between the tactile fingers 21 to 25 and the tool device may be a passive joint with one degree of freedom or two degrees of freedom. Also in this case, if the mounting points provided on the tool device are rotatably connected to the receiving portions provided at the tips of the tactile fingers 21 to 25, the passive joints are connected to those connecting portions. Therefore, the degree of freedom of the mounting mode of the tool device can be increased. However, even if those connecting portions are completely fixed (0 degrees of freedom), if the tactile fingers 21 to 25 have a high degree of freedom in the first place, it is possible to deal with various tool devices. .

The tactile interface of the above embodiment is largely
1) To make it possible to change the operation mode of the exchangeable device device in various ways.
2) Considering the possibility of presenting the rotational (friction) moment acting on the operator's fingertips when gripping an object, and 3) Considering the increase in operability of tactile fingers and the suppression of joint changes in the arm mechanism Controlling the position and posture of the arm mechanism 12,
However, any one or two of them may be omitted.

  The tactile interface arm mechanism 12 and the link structure (number of links, the number of joints, etc.) of the tactile fingers 21 to 25 or the number of tactile fingers are not limited to the configuration exemplified in the above embodiment, but can be arbitrarily changed. May be. However, it is desirable to ensure 6 or more degrees of freedom for the arm mechanism in order to follow the force generation point sufficiently flexibly in accordance with the movement of the operator's arm. In addition, in order to attach various tool devices and perform tactile finger movements that follow the movement of the operator's fingers sufficiently flexibly, it is necessary to secure a certain number of tactile fingers and a certain degree of freedom.

The side view which shows the whole structure about the tactile interface which concerns on one Embodiment of this invention. The schematic diagram which shows the link structure of the arm mechanism of the tactile interface. The perspective view which shows typically the structure of the tactile finger of the same tactile interface. The perspective view which shows the perspective structure of the scissors-type tool device which can be attached to the same tactile interface. The perspective view which shows typically an example of the attachment aspect of the said saddle-type tool device with respect to the tactile interface. The graph which shows the measurement result of the resistive force accompanying the opening / closing operation of the vertical tool device in the state attached to the tactile interface. The perspective view which shows typically an example of the attachment aspect of the female-type tool device with respect to the tactile interface. The perspective view which shows typically an example of the attachment aspect of the syringe type tool device with respect to the tactile interface. The perspective view of the finger folder which can be attached to the same tactile interface. Sectional drawing which shows the side part cross-section about the modification of the finger folder to which the presentation function of the rotational moment was provided. The perspective view which shows the generation | occurrence | production aspect of the rotational moment which acts on a fingertip when an object is hold | gripped.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Column, 11 ... Arm base, 12 ... Arm mechanism, 13 ... Arm 1st link, 14 ... Arm 2nd link, 15 ... Shoulder joint part, 16 ... Elbow joint part, 17 ... Wrist joint part, 18 ... External control Device (control means) 20 ... tactile finger base, 21 ... first tactile finger, 22 ... second tactile finger, 23 ... third tactile finger, 24 ... fourth tactile finger, 25 ... fifth tactile finger, 26 ... finger 1st link, 27 ... 2nd finger link, 28 ... 1st finger joint, 29 ... 2nd finger joint, 30 ... 3-axis force sensor, 31 ... permanent magnet, 32 ... ball bearing (passive ball joint), 33 78 ... Articulated ball (passive ball joint), 40 ... Saddle type tool device, 41 ... Blade part, 42 ... Grip part, 43 ... Support point part, 44, 45 ... Blade, 50 ... Female tool device, 60 ... Syringe type Tool device 61 ... Cylinder part 62 ... Piston part 70 ... Finger folder 7 , 75 ... folder unit, 76 ... rotating plate, 77 ... motor (actuator).

Claims (9)

In a tactile interface comprising a tactile finger base that is spatially moved by an arm mechanism, and a plurality of tactile fingers that are provided on the tactile finger base and are used for operation input and force output, respectively.
A tactile interface comprising: a plurality of types of tool devices having different operation modes; and a mounting point that can be detachably connected to a receiving portion provided at a tip of the tactile finger. The tactile interface according to claim 1, wherein the attachment point is rotatably connected to the receiving portion. The tactile interface according to claim 1, wherein the mounting point and the receiving part form a ball joint. The tactile interface according to any one of claims 1 to 3, wherein the attachment point and the receiving portion are connected by a magnetic force. In the tool device, a rotary plate that is rotatably supported is provided at a portion where an operator's fingertip abuts at the time of operation, and an actuator that applies rotational torque to the rotary plate is provided. The haptic interface according to any one of claims 1 to 4. A tactile finger base that is moved in space by an arm mechanism, a plurality of tactile fingers provided on the tactile finger base and used for input of operation and output of force sense, and provided at the tip of the tactile finger, A tactile interface comprising: a finger folder that holds a fingertip;
A rotating plate that is in contact with the fingertip of the operator held inside the finger folder and is rotatably supported by the operator;
An actuator that generates rotational torque applied to the rotating plate;
A tactile interface characterized by comprising: The haptic interface according to any one of claims 1 to 6,
In order to drive the arm mechanism from the current position and posture to the target position and posture from the index value of the operability of the tactile finger when the arm mechanism is driven to the target position and posture A tactile interface comprising: control means for controlling the position and posture of the arm mechanism so that a value obtained by subtracting the index value of the degree of change in the joint angle of the arm mechanism is maximized. In a tactile interface comprising a tactile finger base that is spatially moved by an arm mechanism, and a plurality of tactile fingers that are provided on the tactile finger base and are used for operation input and force output, respectively.
In order to drive the arm mechanism from the current position and posture to the target position and posture from the index value of the operability of the tactile finger when the arm mechanism is driven to the target position and posture A tactile interface comprising: control means for controlling the position and posture of the arm mechanism so that a value obtained by subtracting the index value of the change amount of the joint angle of the arm mechanism is maximized. A method for controlling a tactile interface comprising a tactile finger base moved in space by an arm mechanism and a plurality of tactile fingers provided on the tactile finger base and used for input of operation and force sense,
In order to drive the arm mechanism from the current position and posture to the target position and posture from the index value of the operability of the tactile finger when the arm mechanism is driven to the target position and posture A control target for the tactile interface, wherein the control target of the position and orientation of the arm mechanism is calculated so that the value obtained by subtracting the index value of the change amount of the joint angle of the arm mechanism is maximized.

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