JP2010102560A - Gripping sense exhibition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gripping sense exhibition device for exhibiting an article gripping sense to a hand of a person. <P>SOLUTION: A gripping sense exhibition part 2 of the gripping sense exhibition device includes a servo motor 10, a differential mechanism 20, and two inner force sense exhibition parts 30, 40. The inner force sense exhibition part 30 includes a pedestal 31, a ball screw 32, a slider 33, slide rails 34a, 34b, a finger rest block 35, a pressure sensor 36, a fixed side unit 37, and a support side unit 38. The ball screw 32 is held by the fixed side unit 37 and the support side unit 38, and is rotatable around an X-axis as an axis. A miter gear 21a is attached to the ball screw 32. The ball screw 32 is rotated around the X-axis as the axis, when rotating a motor shaft 11 of the servo motor 10. The slider 33 is attached to the ball screw 32 and the slide rails 34a, 34b, and includes a ball nut 33a, and a nut support plate 33b for attaching the ball nut 33a. The slider 33 is rectilinearly moved along an X-direction, when rotating the ball screw 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a force sense presentation device that presents a force sense to a person, and more particularly, to a grip sense device for presenting a sense of grasping a virtual object to a human hand.

  In recent years, research on technologies for presenting virtual reality to people has been actively conducted. Representative examples of such technologies include virtual reality and mixed reality. Virtual reality is a technology that artificially creates reality by combining computer graphics and sound effects. Mixed reality is a technology that combines interactive three-dimensional computer graphics and real space.

  In presenting virtual reality, it is necessary to stimulate the human senses as if there were actually objects. In particular, the presentation of force sense is important for generating virtual reality. Research on haptic presentation has been made so far, and several devices for presenting haptic have already been developed.

  A representative example of the haptic device is PHANTOM (registered trademark) (see Non-Patent Document 1, for example). The appearance of PHANTOM (registered trademark) is shown in FIG. Referring to FIG. 1, PHANTOM (registered trademark) includes a pen-shaped stylus 1000. The PHANTOM also includes a motor that applies force to the stylus 1000. The force that the motor applies to the stylus 1000 is determined according to the position of the stylus 1000. Therefore, when the user of PHANTOM grasps and moves the stylus 1000, the user senses a force sense such as hard or soft according to the position of the stylus.

  So far, various studies have been conducted on the presentation of virtual reality using PHANTOM (registered trademark). For example, Non-Patent Document 2 describes research on enhancing the sense of presence when simultaneously presenting and touching a user with force information presented by the force sense presentation device PHANTOM and voice information generated when touching an object. There is disclosure. Non-Patent Document 2 discloses a program in which PHANTOM detects how to touch various things, and automatically generates a sound suitable for it.

  SPIDAR is a well-known haptic device similar to PHANTOM (registered trademark) (see, for example, Non-Patent Document 3 and Non-Patent Document 4). The appearance of SPIDAR is shown in FIG. The SPIDAR includes a haptic pointer 2100 and a plurality of wires 2200 connected to the haptic pointer 2100. The SPIDAR calculates the position and posture of the haptic pointer 2100 from the length of each wire 2200, and presents the haptic according to the position and posture by the tension of the wire 2200.

Non-Patent Document 5 proposes a tweezers type device that facilitates a selection / movement operation in a spatial work.
http: // www. sensorable. com / products-haptic-devices. htm Juan Liu, Hiroshi Ando “Healing How You Touch: Real-Time Synthesis of Contact Sounds for Multiple Interactions 8th, IEEE Conference on Hen 8th, IEEE Conference on Hen. Akabane et al. “High-resolution haptic rendering with an update frequency of 10 kHz”, Journal of the Virtual Reality Society of Japan, Vol. 9, no. 3, pp. 217-226 (2004) Shoichi Hasegawa, Masaharu Inoue, Manabu Kinki, Makoto Sato, “Tension Calculation Method for Tension-type Force Display”, Journal of the Robotics Society of Japan, Vol. 22, no. 6, pp. 1-6 (2004) Uesaka et al., “Tool-type device that facilitates selection and movement in spatial work”, Interaction 2008, No. 5 101, Information Processing Society of Japan, March 2008

  The above-mentioned PHANTOM (registered trademark) and SPIDAR are not suitable for presenting a sense when an object is held with a plurality of fingers.

  First, using these devices, it is difficult to present force sensations at a plurality of locations. Each of these devices has only one location for presenting a force sense, and cannot present a force sense at a plurality of locations. In order to present a sense of force at a plurality of locations, a combination of a plurality of these devices may be considered, but this method complicates the device configuration.

  Also, it is said that an important factor for judging the hardness when grasping an object is the force (terminal force) when the reaction force becomes the largest after the grasping. However, in these devices, the force (presentation force) that the device can output is too small to present the terminal force when gripping a hard object. For example, the presentation power of PHANTOM (registered trademark) is currently 3.3 to 37.5N. Moreover, the presentation power of SPIDAR in Non-Patent Document 4 is 5N for each axis.

  The reason why PHANTOM (registered trademark) and SPIDAR cannot present a large force is because these devices transmit the force of the motor to the point where the force is presented by a wire. Due to the elasticity of the wires, these devices cannot present a large force suddenly. Further, in PHANTOM, a force is applied in the vertical direction to the elongated bar-like arm, so that there is a problem that the arm is easily distorted due to elasticity.

  Furthermore, these are stationary devices, and there is a problem that the range in which a force sense can be presented is limited to the vicinity of the installation location of the device.

  The tweezers type device described in Non-Patent Document 5 cannot present an arbitrary force sense. Non-Patent Document 5 discloses using a ratchet type or drum brake type reaction force presentation mechanism of a tweezers type device, but there are only two types of force sensations in a state where the tweezers are fixed or a state where the tweezers are not fixed. Cannot output.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a grasping sensation device for presenting a sense of grasping an object to a human hand. Furthermore, it is an object to provide a portable grip sensor device.

  The present invention according to one aspect is a gripping sensation presentation device that presents a gripping sensation of a virtual object to a user, and includes a drive unit that generates a rotational force and a plurality of force presentation units. Each force presentation unit includes a rod-like screw that is connected to the drive unit and rotates in accordance with the rotational force, and a slider unit that is connected to the screw and moves in the axial direction of the screw in accordance with the rotation of the screw. The grasping sensation presentation device further includes detection means for detecting information related to the action of the external object applied to each slider part, and control means for controlling the operation of the drive part based on the detection result of the detection means. The control means includes a storage means for storing gripping object information representing a characteristic of stress applied to the outside by the virtual object, and a drive section so that the slider section generates a stress corresponding to the characteristics based on the detection result and the gripping object information. Signal generating means for generating a drive signal for controlling the motor.

  Preferably, the plurality of force presentation units include a first force presentation unit and a second force presentation unit facing each other.

  More preferably, the drive unit includes a motor and a force transmission unit that converts rotation of the motor into rotation of a screw of the first force presentation unit and a screw of the second force presentation unit.

More preferably, the force transmission unit has a differential mechanism.
Preferably, the slider part of the first force presentation unit and the slider part of the second force presentation unit move by different distances with respect to the drive signal.

Preferably, the detection means includes a pressure sensor installed in each slider portion.
Preferably, the detection means includes an encoder that detects a rotation amount of the drive unit.

  Preferably, each screw is a ball screw.

  The device according to the present invention includes a plurality of screw mechanisms, and each screw mechanism presents a force to the user. As a result, it is possible to provide a gripping sensation device that can present a sensation (force sense) when a hard object is gripped. Alternatively, according to the present invention, a portable grip sensor device can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(1. Overall configuration)
The outline | summary of the holding | grip sense presentation device 1 which concerns on this invention is demonstrated with reference to FIG. FIG. 3 is a diagram illustrating an appearance of the grasping sensation presentation device 1. With reference to FIG. 3, the grip sensation presentation device 1 includes a grip sensation presentation unit 2, a control device 3, and a cable 4.

  The grasping sensation presentation unit 2 presents a force received from the virtual object when the user grasps the virtual object. Here, the characteristic of the force (stress) applied to the user by the virtual object is determined in advance and stored in the control device 3. Details of the grip sense presentation unit 2 will be described later.

  The control device 3 controls the operation of the grasping sensation presentation unit 2. That is, the control device 3 obtains the stress to be presented to the outside based on the detection result of the information regarding the action given by the external object to the grasping sensation presentation unit 2 and causes the grasping sensation presentation unit 2 to present the reaction force. Details of the control device 3 will be described later.

  The cable 4 connects the grip sensation presentation unit 2 and the control device 3, and transmits a signal between the grip sensation presentation unit 2 and the control device 3. The cable 4 supplies power to the grasping sensation presentation unit 2. However, when the grip sense presentation unit 2 is driven by a built-in battery, it is not necessary to supply power. Furthermore, the cable 4 is not necessary if the grasping sensation presentation unit 2 and the control device 3 are provided with a wireless communication function.

(2. Holding sense presentation part)
The configuration of the grasping sensation presentation unit 2 will be described with reference to FIGS. 4 and 5. FIG. 4 is a top view of the grip sense presentation unit 2. FIG. 5 is a side view of the grip sense presentation unit 2. As shown in FIG. 5, the grip sense presentation unit 2 includes a servo motor 10, a force transmission unit 20, and two force sense presentation units 30 and 40.

  The servo motor 10 receives the supply of electric power from the control device 3 and rotates the motor shaft 11. Here, the direction of the motor shaft 11 is the Z direction. The operation of the servo motor 10 is controlled by a signal from the control device 3. Details of the operation control of the servo motor 10 by the control device 3 will be described later.

  The force transmission unit 20 converts the rotational motion of the motor shaft about the Z direction into the rotational motion about the X direction. The force transmission unit 20 includes a motor side gear attached to the motor shaft and two conversion gears that mesh with the motor side gear. The two conversion gears are connected to the force sense presentation units 30 and 40, respectively. Here, the miter gear 21a and the miter gear 21b are used as the conversion gears.

  4 and 5, the force sense presentation unit 30 includes a pedestal 31, a ball screw 32, a slider 33, slide rails 34a and 34b, a finger rest 35, a pressure sensor 36, and a fixed unit. 37 and a support side unit 38.

  The pedestal 31 is a rectangular plate and is arranged such that the longitudinal direction is in the X direction and the minor axis direction is in the Y direction. The pedestal 31 is fixed to the servo motor 10. In addition, slide rails 34 a and 34 b are arranged on the surface of the base 31 at a predetermined interval along the X direction.

  A fixed-side unit 37 is arranged at one end (not connected to the servo motor 10) in the longitudinal direction of the base 31. A support side unit 38 is disposed at the other end of the pedestal 31 in the longitudinal direction.

  The ball screw 32 is held by the fixed side unit 37 and the support side unit 38, and is rotatable about the X direction in FIGS. A miter gear 21 a is attached to the ball screw 32. When the motor shaft 11 of the servo motor 10 rotates, the ball screw 32 rotates about the X direction.

  The slider 33 is attached to the ball screw 32 and the slide rails 34a and 34b, and includes a ball nut 33a and a nut support plate 33b to which the ball nut 33a is attached. When the ball screw 32 rotates, the slider 33 moves linearly in the X direction. The movable range is between the fixed side unit 37 and the support side unit 38.

  The finger rest 35 is attached to the slider 33. The finger rest 35 moves as the slider 33 moves. FIG. 4 shows the finger rest 35 in the most closed state and the finger rest 35 # in the most open state.

  Here, the finger rest 35 is assumed to be L-shaped, but the shape is not limited to this. The finger rest 35 only has to protrude from the base 31 in the XY plane so that the user can place a finger.

  Both the slider 33 and the finger rest 35 move linearly according to the rotation of the ball screw 32. These are collectively called “slider part”. In the above description, the slider 33 and the finger rest 35 are described as separate ones, but they may be integrated. However, when a commercially available ball screw mechanism (a combination of the ball screw 32 and the slider 33) is used for the grasping sensation presentation unit 2, the configuration is as shown in FIG.

  The pressure sensor 36 is disposed on the surface of the finger rest 35. The pressure sensor 36 detects the pressure applied to the finger rest 35 from the outside.

  The structure of the force sense presentation unit 40 is substantially the same as the structure of the force sense presentation unit 30. The force sense presentation unit 40 includes a pedestal 41, a ball screw 42, a slider 43, slide rails 44 a and 44 b, a finger rest 45, a pressure sensor 46, a fixed side unit 47, and a support side unit 48. . Since the structure and function of each part are the same as each part of the force sense presentation unit 40, the description thereof will not be repeated.

  The force sense presentation unit 30 and the force sense presentation unit 40 face each other. That is, the axes of the ball screw 32 and the ball screw 42 coincide. Further, the screw grooves of the ball screw 32 and the ball screw 42 are cut so that the slider 33 and the slider 43 move in the opposite directions with respect to the rotation of the motor shaft.

  The force sense presentation units 30 and 40 convert the rotational motion of the servo motor 10 into linear motion using screws and sliders (collectively referred to as a screw mechanism). 40 can present a greater force to the user than a device that presents force with a conventional wire. In this embodiment, a ball screw is used for the screw mechanism, but a screw other than the ball screw, for example, a sliding screw may be used. However, it is preferable to use a ball screw from the viewpoint of energy efficiency.

  The configuration of the gripping sensation presentation unit 2 is not limited to that shown in FIGS. 4 and 5. A grip sensation presentation unit 2 # having a configuration different from the grip sensation presentation unit 2 described above will be described with reference to FIG. FIG. 6 is a side view of the grip sensation presentation unit 2 #. However, the description of the configuration common to the grasping sensation presentation unit 2 will not be repeated.

  The grasping sensation presentation unit 2 # includes a servo motor 10, an encoder 12, a force transmission unit 20 #, and two force sense presentation units 30 and 40.

  The encoder 12 is mounted on the servo motor 10 and detects the number of rotations of the motor shaft. The encoder 12 outputs the detected rotation speed to the control device 3.

  Force transmission unit 20 # includes a differential device. The differential device includes a motor-side gear 22, a gear 24 connected to the ball screw 32, and a gear 26 connected to the ball screw 42. The force transmission unit 20 # functions in the same manner as the force transmission unit 20 in that the rotational movement of the motor shaft about the Z direction is converted into the rotational movement about the X direction. However, the force transmission unit 20 # includes a differential device, so that the ball screw 32 and the ball screw 42 can be rotated at different rotational speeds.

  A usage form of the grip sensation presentation unit 2 will be described with reference to FIG. FIG. 7A is a view of the state in which the user has the grasping sensation presentation unit 2 as viewed from the −Y side in FIG. 4 or FIG. 5. FIG. 7B is a view of the state in which the user has the grasping sensation presentation unit 2 as viewed from the + Y side in FIG. 4 or FIG. The user holds the servo motor 10 and puts a thumb on one finger rest and puts an index finger on the other finger rest.

(3. Control device)
A functional configuration of the control device 3 will be described with reference to FIG. FIG. 8 is a block diagram illustrating a functional configuration of the control device 3. FIG. 8 also shows peripheral devices of the control device 3 in addition to the control device 3. Here, as a peripheral device, a grasping sensation presentation unit 2 #, a personal computer 5, and a monitor 6 are shown.

  The control device 3 includes a sensor amplifier 102, a digital conversion circuit (ADCNV) 104, a pressure calculation unit 106, a serial converter 112, a servo motor amplifier (AMP) 114, a position calculation unit 116, and a speed calculation. Unit 118, grasped object information holding unit 120, position control unit 122, speed control unit 124, thrust control unit 126, and analog conversion circuit (DACNV) 128.

  The sensor amplifier 102 amplifies analog signals (hereinafter referred to as pressure signals) from the pressure sensors 36 and 46 of the grasping sensation presentation unit 2. The digital conversion circuit 104 converts the pressure signal amplified by the sensor amplifier 102 into a digital signal. The pressure calculation unit 106 calculates the pressure applied to the sliders 33 and 43 based on the pressure signal converted into the digital signal.

  The serial converter 112 converts a signal (referred to as a rotation amount signal) about the rotation amount of the motor shaft 11 output by the encoder 12 at regular time intervals into a serial data string. The amplifier 114 amplifies the rotation amount signal converted by the serial converter 112.

  The position calculation unit 116 calculates the positions of the sliders 33 and 43 based on the amplified rotation amount signal and the design information of the grasping sensation presentation unit 2. Here, the design information of the grip sensation presentation unit 2 includes the number of gears of each gear (gear 22, gear 24, gear 26) of the force transmission unit 20 and the pitch of the ball screws 32 and 42.

  The speed calculation unit 118 calculates the speeds of the sliders 33 and 43 based on the positions of the sliders 33 and 43 calculated by the position calculation unit 116 at a plurality of times and the measurement times of the positions.

  The gripping object information holding unit 120 stores gripping object information. As the gripping object information holding unit 120, a readable / writable storage device such as a RAM (Random Access Memory) or a flash memory can be used.

  The grasped object information represents the characteristics of the virtual object to be reproduced by the grasping sensation presentation device 1. That is, the gripping object information holding unit 120 represents a characteristic of stress that a virtual object that is considered to be in contact with the real object should apply to the real object. Specifically, the gripping object information is a set of values indicating how much force is required to push the virtual object (or how much stress is returned when the virtual object is pushed). Includes multiple. By setting various values of the stress at the time of deformation of the virtual object, it is possible to express the grip sensation of the object having various hardnesses.

  As the gripping object information, for example, sample data obtained by measuring an actual object can be used. It is also possible for the user of the grasping sensation presentation device 1 to create parameters by inputting parameters, that is, external force values and stress values.

  In the present embodiment, the control device 3 receives gripping object information from the personal computer 5 and stores the received gripping object information in the gripping object information holding unit 120. For example, the user can connect the force sensor to the personal computer 5 and create gripping object information on the personal computer 5 using the measurement result of the force sensor.

  The position control unit 122 determines the position of the sliders 33 and 43 at the next time t + dt based on the gripping object information stored in the gripping object information holding unit 120 and the position of the sliders 33 and 43 at the time t calculated by the position calculation unit 116. A position control signal for specifying is generated. Specifically, first, the position control unit 122 obtains a stress value based on the gripping object information and the positions of the sliders 33 and 43 at time t. Then, the position control unit 122 obtains a value obtained by dividing the stress value by the total mass of the slider and the finger, that is, the acceleration of the slider. Finally, the position control unit 122 obtains a position control signal based on the positions of the sliders 33 and 43 at time t and the acceleration of the slider.

  Further, the position control unit 122 transmits the position information of the sliders 33 and 43 to the personal computer 5. The personal computer 5 displays an image of the virtual space on the monitor 6 based on the position information. For example, the personal computer 5 displays a finger image on the monitor 6 at a position in the screen corresponding to the positions of the sliders 33 and 43. Further, the personal computer 5 displays an image of the virtual object to be grasped on the monitor 6. As described above, when the personal computer 5 and the monitor 6 are combined with the grasping sensation presentation device 1, an image of the virtual space can be displayed in addition to the force sense presentation, so that the virtual object can be reproduced more realistically.

  The speed control unit 124 includes the gripping object information stored in the gripping object information holding unit 120, the speeds of the sliders 33 and 43 at the time t calculated by the speed calculation unit 118, and the position control signal generated by the position control unit 122. Based on the above, a speed control signal for designating the speed of the sliders 33 and 43 at the next time t + dt is generated. Specifically, for example, the speed control unit 124 obtains a speed control signal as follows. First, the speed control unit 124 obtains a change in the position of the slider from the position control signal and the positions of the sliders 33 and 43. Then, the speed control unit 124 obtains a speed change from the position change, and calculates a speed control signal from the obtained speed change and the speeds of the sliders 33 and 43 at time t.

  The thrust control unit 126 generates a thrust control signal that specifies the thrust of the sliders 33 and 43 based on the speed control signal generated by the speed control unit 124. Specifically, the thrust control unit 126 first calculates the acceleration of the sliders 33 and 43 from the speed of the sliders 33 and 43 calculated by the speed calculation unit 118 and the speed control signal. Then, the thrust control unit 126 calculates the rotational speed of the servo motor 10 and the thrust control signal to be given to the servo motor 10 based on the calculated acceleration and the design information of the gripping sense presentation unit 2. The thrust control unit 126 may calculate the thrust to be generated by the sliders 33 and 43 based on the positions of the sliders 33 and 43 calculated by the position calculation unit 116 and the gripping object information.

  The analog conversion circuit 128 converts the thrust control signal into an analog signal. The amplifier 114 amplifies the thrust control signal converted by the analog conversion circuit 128 and outputs a drive signal for driving the servo motor 10 to the servo motor 10. The amplifier 114 amplifies the signal with a predetermined amplification factor based on the design information of the grasping sensation presentation unit 2, the characteristics of the analog conversion circuit 128, and the like. Here, it is assumed that the drive signal is a current for driving the servo motor 10.

  The control device 3 can also control the servo motor 10 based on information from the pressure sensors 36 and 46.

  In this case, the speed control unit 124 calculates a speed control signal based on the pressure applied to the pressure sensors 36 and 46 calculated by the pressure calculation unit 106 and the gripping object information stored in the gripping object information holding unit 120. . The thrust control unit 126 calculates a thrust control signal based on the speed control signal calculated in this way and the pressure value calculated by the pressure calculation unit 106.

  Thus, controlling the servo motor 10 based on information from the pressure sensor can control the stress more accurately than based on the information from the encoder 12. However, if there is a situation where a pressure sensor cannot be provided, the control device 3 may control the servo motor 10 based on information from the encoder 12.

  FIG. 9 is a flowchart showing processing performed by the control device 3 when the servo motor 10 is controlled using information from the encoder 12. Hereinafter, processing performed by the control device 3 will be described collectively with reference to FIG.

  In step S <b> 101, the position calculation unit 116 in the control device 3 acquires the rotation amount signal of the servo motor 10 detected by the encoder 12. Specifically, here, the rotation amount signal acquired by the position calculation unit 116 is obtained by converting the rotation amount signal output from the encoder 12 by the serial converter 112 and amplifying by the amplifier 114.

  In step S103, the position calculation unit 116 calculates the position information of the sliders 33 and 43 based on the rotation amount signal acquired in step S101 and the design information of the grasping sensation presentation unit 2. In this processing, the position calculation unit 116 may store a table in which the rotation amount signal and the position information are associated with each other in advance, and obtain the position information based on the table and the acquired rotation amount signal.

  In step S105, the speed calculation unit 118 in the control device 3 calculates the speeds of the sliders 33 and 43 based on the position information obtained by the position calculation unit 116 in step S103.

  In step S107, the position calculation unit 116 outputs the position information obtained in step S116 to the personal computer 5. The personal computer 5 that has received the position information displays a virtual space screen corresponding to the position information on the monitor 6.

  In step S109, the position control unit 122 is based on the gripping object information stored in the gripping object information holding unit 120 and the positions of the sliders 33 and 43 at time t calculated by the position calculation unit 116 in step S103. A position control signal for designating the positions of the sliders 33 and 43 at the next time t + dt is generated.

  In step S111, the speed control unit 124 determines the gripping object information stored in the gripping object information holding unit 120, the speeds of the sliders 33 and 43 at the time t calculated by the speed calculation unit 118 in step S105, and the position control unit. Based on the position control signal generated by 122, a speed control signal for designating the speed of the sliders 33 and 43 at the next time t + dt is generated.

  In step S113, the thrust control unit 126 generates a thrust control signal that specifies the thrust of the sliders 33 and 43 based on the speed control signal generated by the speed control unit 124 in step S111. Alternatively, the thrust control unit 126 generates a thrust control signal based on the position information and gripped object information calculated by the position calculation unit 116 in step S103.

  In step S115, the analog conversion circuit 128 converts the thrust control signal into an analog signal. The amplifier 114 amplifies the thrust control signal converted by the analog conversion circuit 128 and creates a drive signal for driving the servo motor 10. Further, the amplifier 114 outputs a drive signal to the servo motor 10.

  In step S117, the control device 3 determines whether a predetermined time has elapsed since the execution of step S101. When control device 3 determines that the predetermined time has elapsed (YES in step S117), it repeats the series of processing from step S101. Until a predetermined time has elapsed from the execution of step S101, the control device 3 waits without starting the execution of the process from step S101 again.

  The control device 3 can determine whether or not a predetermined time has elapsed since the execution of step S101 by allowing the position calculation unit 116 to measure the time. Alternatively, a clock unit that measures the time provided outside the position calculation unit 116 may send a command for acquiring rotation amount information to the position calculation unit 116 at predetermined time intervals. In any case, the control device 3 only needs to be able to repeatedly execute the processing from step S101 to step S115.

  FIG. 10 is a flowchart showing processing performed by the control device 3 when the servo motor 10 is controlled using information from the pressure sensors 36 and 46. Hereinafter, processing performed by the control device 3 will be described collectively with reference to FIG.

  In step S <b> 201, the pressure calculation unit 106 in the control device 3 acquires pressure signals from the pressure sensors 36 and 46. Specifically, here, the pressure calculation unit 106 acquires, from the digital conversion circuit 104, a signal obtained by converting the pressure signal output from the pressure sensors 36 and 46 by the digital conversion circuit 104.

  In step S203, the pressure calculation unit 106 calculates the pressure value applied to the pressure sensors 36 and 46 based on the pressure signal acquired in step S201.

  In step S <b> 205, the speed control unit 124 calculates a speed control signal based on the pressure value calculated by the pressure calculation unit 106 in step S <b> 203 and the gripping object information stored in the gripping object information holding unit 120.

  In step S207, the thrust control unit 126 calculates a thrust control signal based on the pressure value calculated in step S203 and the speed control signal calculated in step S205.

  In step S209, the analog conversion circuit 128 converts the thrust control signal into an analog signal. The amplifier 114 amplifies the thrust control signal converted by the analog conversion circuit 128 and creates a drive signal for driving the servo motor 10. Further, the amplifier 114 outputs a drive signal to the servo motor 10.

  In step S211, the control device 3 determines whether a predetermined time has elapsed since the execution of step S201. When control device 3 determines that the predetermined time has elapsed (YES in step S211), it repeats the series of processing from step S201. Until a predetermined time has elapsed from the execution of step S201, the control device 3 waits without starting the execution of the process from step S201 again. The control device 3 can determine whether or not the predetermined time has elapsed by a method similar to the method described in step S117 in FIG.

  The information from the encoder 12 and the information from the pressure sensors 36 and 46 have been described above as information for controlling the servo motor 10. However, the information for controlling the servo motor 10 is not limited to these. The control device 3 only needs to be able to receive information that can calculate the pressure applied to the sliders 33 and 43.

  Therefore, the grasping sensation presentation device 1 is not necessarily provided with a pressure sensor or an encoder. The pressure sensor or the encoder detects information related to the action applied to the finger rest (position information of the sliders 33 and 43, pressure information applied to the sliders 33 and 43, or both position information and pressure information). It is an example. Instead of these, other detection means may be used. For example, the grasping sensation presentation device 1 may include a measuring device for counter electromotive force generated in the servo motor 10. The control device 3 calculates the pressure applied to the finger rest from the back electromotive force.

(4. Device performance)
The grip sensation presentation device 1 according to the present embodiment has sufficient performance to present a grip sensation to the user. This will be described below.

First, conditions necessary for presenting a gripping feeling will be described. This condition has been clarified by subject experiments (Koichi Nakayama, Naomi Inoue, “Verification Experiment of Hardness Discrimination Performance at Fingertips for Creation of Hardness Sense Presenting Device”, 127th Human Computer Interaction Study Group IPSJ, January 2008). In this subject experiment, an experimental apparatus that can control the fingertip position when the fingertip collides with the virtual object with an accuracy of 1 ms and 1 μm and can present a force of 250 N and an acceleration of 200 m / s ² is used. Using an experimental device, the trajectory of the fingertip when the fingertip collides with a virtual object is reproduced, and the hardness discrimination ability only with the sense of the fingertip is verified.

There are the following three parameters representing the hardness of an object.
(I) Acceleration when the fingertip collides with the object and repels (ii) Contact time when the fingertip collides with the object and repels (iii) Depth of sinking when the fingertip collides with the object and stands still Hardness is infinite Since there is no perfect rigid body that becomes large, there is a finite contact time from when the fingertip touches the object until it leaves, and a finite acceleration applied to the fingertip at the time of collision. In general, the softer the longer the contact time and the lower the acceleration. When the fingertip collides with an object and stops, the object sinks by a finite depth. Softer objects have greater depth of sinking.

In this experiment, six types of contact time {10, 20, 40, 80, 160, 320 (ms)}, six types of acceleration {5, 10, 20, 40, 80, 160 (m / s ² )}, From the six types of sinking depths {1, 2, 4, 8, 16, 32 (mm)}, two adjacent values are presented to the subject. Then, ask the subject to answer whether the change can be discriminated.

The experimental results are shown in FIGS. FIG. 11 to FIG. 13 are diagrams showing experimental results for acceleration, contact time, and sinking depth, respectively. From these experimental results, it was found that the discrimination threshold for acceleration was 20 m / s ² , the discrimination threshold for contact time was 40 ms, and the discrimination threshold for subsidence depth was 4 mm. Accordingly, the grasping sensation presentation device has an acceleration of 20 m / s ² or more when colliding with an object and repelling, a time when the fingertip is in contact with the object is 40 ms or less, and an overshoot of the fingertip position when colliding with the object and stationary. Must be capable of realizing the condition of 2 mm or less.

  The grasping sensation presentation device 1 according to the present embodiment has the above performance. This will be described below with reference to FIGS.

  FIG. 14 is a diagram showing the fingertip speed and the fingertip interval presented by the grasping sensation presentation device 1. The horizontal axis of the graph shown in FIG. 14 represents time (unit: s). The upper graph shows the time variation of the fingertip speed, and the vertical axis of the graph represents the fingertip speed (unit: mm / s). The value above the origin 0 indicates the speed at which the fingertips are opened, and the value below the origin 0 indicates the speed at which the gap between the fingertips is closed. The lower graph shows the time change of the fingertip interval, and the vertical axis of the graph represents the fingertip interval (unit: mm).

  FIG. 15 is an enlarged view of the time change of the fingertip interval. FIG. 15 is an enlarged view of a portion surrounded by a frame 1410 in FIG. Referring to FIG. 15, the overshoot generated at the time of force sense is about 1 mm for one slider, that is, about 2 mm for both sliders, and satisfies the above condition.

  FIG. 16 is an enlarged view of the time change of the fingertip speed. FIG. 16 is an enlarged view of a portion surrounded by a frame 1420 in FIG. One scale on the horizontal axis in FIG. 16 is 100 ms as in FIG. Therefore, with reference to FIG. 16, it can be seen that the contact time of the grasping sensation presentation device 1, that is, the time from the rigid body collision until the speed becomes 0 is 10 ms or less. It should be noted that the positive speed appears after the rigid collision due to overshoot.

In addition, referring to FIG. 16, it can be seen that 40 m / s ² = (400 mm / s) / (10 ms) can be realized with one slider, that is, an acceleration of 80 m / s ² can be realized with both sliders.

  As described above, the grip sensation presentation device 1 according to the present embodiment has sufficient performance to present a grip sensation.

  The grasping sensation presentation device 1 includes two stands (finger rests) that are fixed to a slider of a ball screw and present a force sense to two fingers, respectively. The grasping sensation presentation device 1 controls the force to be presented on the finger rest with a motor connected to the ball screw. The grasping sensation presentation device 1 transmits a presentation force to a fingertip when grasping an object using a ball screw having high rigidity without using a wire. Therefore, the grasping sensation presentation device 1 has a small distortion and can present a large force rapidly. The gripping sensation presentation device 1 can make a fingertip feel various hardness sensations, from a sensation when grasping a hard object to a sensation when grasping a soft object.

  Since the ball screw is a technology completed as an industrial machine, a large force can be instantly presented and control is relatively easy. Therefore, the grasping sensation presentation device 1 has a low price and high performance.

  In addition, the grasping sensation presentation device 1 is smaller and lighter than conventional devices such as PHANTOM and SPIDAR. In addition, the grasping sensation presentation device 1 is a portable device that has a much smaller movement range than conventional devices. Therefore, the grip sense presentation device 1 can present the hardness of the virtual object anywhere in the place where the arm can be moved.

(5. Other)
The movement amounts of the two slider portions may be different. In particular, it is preferable to move the slider part for the index finger largely compared to the slider part for the thumb. By doing in this way, a more natural grip feeling can be presented to the user. In order to change the movement amount, for example, a force transmission unit having a differential mechanism such as the force transmission unit 20 # may be used. Alternatively, the number of gears connected to the ball screw may be changed, or the pitch of the ball screw may be changed.

  In the above embodiment, one motor provides driving force to the two force sense presentation units. However, the grasping sensation presentation device may include two motors. In this case, the grasping sense presentation device drives the two force sense presentation units independently by each motor.

  According to the grip sense presentation device including two motors, the movement amounts of the two slider portions can be freely controlled, and a more natural grip sense can be presented. On the other hand, the grasping sensation presentation device 1 according to the present embodiment can be downsized because the number of motors is small.

  In addition, the grasping sensation presentation device may include three or more force sense presentation units. If the presenting force intersects at one point, the grasping sensation presentation device is portable.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention uses a technology that presents virtual reality (virtual reality: mixed reality) that expresses everything from the sensation of grasping a hard object to the sensation of grasping a soft object. It is suitable for the industrial field. Such industrial fields include, for example, the entertainment industry such as commercial / home game machines. In recent years, haptic devices have also been applied in the field of medical education as practice devices for finding lesions by palpation. The present invention is also expected to be used in this way.

It is a figure which shows the external appearance of PHANTOM (trademark). It is a figure which shows the external appearance of SPIDAR. It is a figure which shows the external appearance of the holding | grip sense presentation device. FIG. 4 is a top view of a gripping sensation presentation unit 2. FIG. 4 is a side view of a grip sense presentation unit 2. It is a side view of grasp sense presentation part 2 #. It is a figure for demonstrating the utilization form of the grip sense presentation part. 3 is a block diagram showing a functional configuration of a control device 3. FIG. 5 is a flowchart showing processing performed by the control device 3 when controlling the servo motor 10 using information from the encoder 12; 4 is a flowchart showing processing performed by the control device 3 when controlling the servo motor 10 using information from the pressure sensors 36 and 46; It is a figure which shows the experimental result about acceleration. It is a figure which shows the experimental result about contact time. It is a figure which shows the experimental result about a subduction depth. It is a figure which shows the fingertip speed and fingertip space | interval which the grip sense presentation device 1 presents. It is an enlarged view of the time change of a fingertip interval. It is an enlarged view of the time change of fingertip speed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Grasping sense presentation device, 2 Grasping sense presentation part, 3 Control apparatus, 4 Cable, 5 PC, 6 Monitor, 10 Servo motor, 11 Motor shaft, 12 Encoder, 20, 20 # Force transmission part, 21a, 21b Miter gear, 22 , 24, 26 gear, 30 force sense presentation unit, 31 pedestal, 32 ball screw, 33 slider, 33a ball nut, 33b nut support plate, 34a, 34b slide rail, 35 finger rest, 36 pressure sensor, 37 fixed side unit, 38 support side unit, 40 force sense presentation unit, 41 base, 42 ball screw, 43 slider, 44a, 44b slide rail, 45 finger rest, 46 pressure sensor, 47 fixed side unit, 48 support side unit, 102 sensor amplifier, 104 Digital conversion circuit, 106 pressure calculation unit, 112 serial converter, 114 amplifier, 116 position calculation unit, 118 speed calculation unit, 120 gripped object information holding unit, 122 position control unit, 124 speed control unit, 126 thrust control unit, 128 analog conversion circuit, 1000 stylus, 2100 force Perception pointer, 2200 wires.

Claims (8)

A gripping sensation presentation device for presenting a gripping sensation of a virtual object to a user,
A drive that generates rotational force;
A plurality of force presentation units,
Each of the force presentation units
A rod-like screw connected to the drive unit and rotating according to the rotational force;
A slider portion connected to the screw and moving in the axial direction of the screw according to the rotation of the screw;
Detecting means for detecting information on the action of an external object applied to each of the slider parts;
Control means for controlling the operation of the drive unit based on the detection result of the detection means,
The control means includes
Storage means for storing gripping object information representing a characteristic of stress applied to the outside by the virtual object;
A gripping sensation presentation apparatus including signal generation means for generating a driving signal for controlling the driving unit so that the slider unit generates the stress corresponding to the characteristic based on the detection result and the gripping object information. .   The grip sense presentation device according to claim 1, wherein the plurality of force presentation units include a first force presentation unit and a second force presentation unit facing each other. The drive unit is
A motor,
The grasping sensation presentation device according to claim 2, further comprising: a force transmission unit that converts rotation of the motor into rotation of the screw of the first force presentation unit and rotation of the screw of the second force presentation unit.   The grasping sensation presentation device according to claim 3, wherein the force transmission unit includes a differential device.   The slider unit of the first force presentation unit and the slider unit of the second force presentation unit move by different distances with respect to the drive signal. The grip sensation presentation device according to claim 1.   The grasping sensation presentation device according to any one of claims 1 to 5, wherein the detection unit includes a pressure sensor installed on each of the slider portions.   The grasping sensation presentation device according to claim 1, wherein the detection unit includes an encoder that detects an amount of rotation of the driving unit.   Each said screw is a ball screw, The holding sense presentation apparatus of any one of Claim 1 to 7.