JP2013061223A - Six-axis force measuring device, and six-axis force measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a six-axis force measuring device and a system therefor, which facilitates manufacturing and downsizing, has flexibility on a contact surface with an article, and can measure six-axis force without depending on complicated stress distortion characteristics of soft material; and a dynamic quantity measuring device and a system therefor, which can be applied for another optical tactile sensor and simultaneously measure six-axis force without the loss of functions of the optical tactile sensor itself.SOLUTION: A six-axis force measuring device 1 includes: a CCD camera 4 and an illumination 5 as shape extracting means; and a pressure sensor 10 or a compressed fluid 19 and a box 20 as pressure extracting means, in addition to a touch pad 3. A CPU 15 extracts a shape of a film 6 and a direction of tension acting on an end of the film 6, from images shot by the CCD camera 4, and extracts a non-contact area in which an article W1 is not contacted with the film 6, from the shape of the film 6. Furthermore, the CPU 15 inputs an analog signal from the pressure sensor 10, and extracts the pressure of liquid 11. Finally, the CPU 15 extracts six-axis force acting on a plate 7 (force and moment in and around an optional axial direction) from the information.

Description

  The present invention relates to a six-axis force measuring device, a six-axis force measuring method, a six-axis force measuring system, an optical tactile sensor, and a mechanical quantity measuring method.

  In recent years, the robot business has been focusing on the development of autonomous robots that can adapt to the environment in cooperation with people, and its practical application is gradually approaching. Unlike industrial robots, in order for robots to act autonomously, they need the ability to recognize the environment like humans, and many tactile sensors have been developed. Among them, there are the most types of sensors that measure the contact force when a robot comes into contact with an object, and the principle is various such as a resistance type, a capacitance type, a piezoelectric type, and an ultrasonic type. However, many sensors based on these principles have a large number of elements arranged on the contact surface, and it is difficult to simplify and miniaturize the structure, leaving many problems for mounting on a robot.

  On the other hand, there is a sensor in which the contact surface is made of an elastic body and information on contact force is obtained from deformation information of the elastic body. Since many elements are not required, it is advantageous for simplification and miniaturization of the structure. Furthermore, since the contact surface is an elastic body, it is a great advantage that it is easy to become familiar with the surrounding environment and contact objects. it is conceivable that. For example, a sensor has been developed that obtains a triaxial force distribution from marker position information by providing a two-layer marker inside an elastic body on a contact surface having a planar shape and photographing the marker with an imaging means. (For example, refer to Patent Document 1) In addition, the contact portion is composed of an elastic body provided with a plurality of columnar protrusions, and the elastic body comes into contact with the internal acrylic plate when the object comes into contact, and the inside of the plate is irradiated. Sensors that acquire a triaxial force distribution have been developed by photographing and analyzing the scattered light phenomenon with an imaging means. (For example, refer to Patent Document 2) In addition, the deformation state of the elastic film is extracted by irradiating the elastic film that is deformed by the contact of the object with light having several colors and photographing it with the imaging means. There are also sensors that calculate the magnitude and direction of the contact force. (For example, see Patent Document 3)

International Publication WO2005 / 029028 JP 7-128163 A JP 2009-145085 PR

  However, the sensors described above can measure the contact force, but are limited to only the measurement of the normal force and the shear force, and many of them do not consider the moment measurement. In order for the robot to recognize the surrounding environment more accurately, a sensor that can acquire multidimensional force information is desirable. Also, most sensors that use many elements on the contact surface and sensors with a structure in which a relatively hard plate is arranged inside the elastic surface (for example, see Patent Document 2) Therefore, it is difficult for the contact surface to be sufficiently deformed, that is, it has a structure that is not easily adapted to the object. For example, it can be said that it is difficult to apply a sensor to a field that requires a stable contact state with an object such as a finger of a robot because a sufficient contact area cannot be secured.

  In the case of a sensor using deformation information of the elastic body on the contact surface, there is a possibility that these problems can be solved, but there are many problems in the method of acquiring force information from the deformation information of the elastic body. Since the relationship between stress and strain of an elastic body is generally complicated, the relationship between stress and strain is experimentally determined based on a method that assumes a linear relationship between stress and strain, and information on deformation and force acquired in advance. However, in these methods, when the elastic body undergoes large deformation or complex deformation, the stress / strain relationship used may deviate from the original relationship, and the measurement accuracy may deteriorate. There is sex.

  The present invention has been made in view of the above-described problems, and by forming a contact portion with an object by an elastic body, a structure that can be easily adapted to the object is realized, and force information is obtained from deformation information of the elastic body. When acquiring the measurement, we use a method that is not easily affected by the complex deformation characteristics of the elastic body by not using the relationship between stress and strain, and further measures the force in six axes without depending on the shape of the object It is in providing a 6-axis force measuring device which makes possible. Another object of the present invention is to provide a new tactile sensor and a mechanical quantity measuring method capable of simultaneously measuring six-axis forces while maintaining the ability of a conventional tactile sensor.

  In order to solve the above-described problem, the invention according to claim 1 is configured such that the deformable film (6) according to the shape of the object that is a contact portion with the object and the object of the film are in contact with each other. The member (7, 8) for fixing the membrane from the side opposite to the side, the shape extracting means (4, 5, 11) for extracting the shape of the membrane, and the side on which the object of the membrane contacts The gist is a six-axis force measuring device including pressure extracting means (10, 19, 20) for extracting the pressure in the side space.

  Therefore, according to the first aspect of the present invention, it is composed of a deformable membrane, a member for holding it, a shape extraction means, and a pressure extraction means, and is processed with a relatively small and simple structure. can do. Therefore, when combined with a conventional optical tactile sensor system or applied to other fields, it can be applied more easily than other six-axis force measuring devices.

  Moreover, since the film | membrane which is a contact part with a target object can deform | transform according to the shape of a target object, it is mentioned that it is easy to become familiar with a target object. Therefore, it is possible to maintain stable contact with the object and to make contact without damaging the object.

The “deformable film” is preferably formed from a silicone resin such as a silicone rubber, but may be formed from other elastic bodies such as other rubbers or elastomers.
According to a second aspect of the present invention, in the first aspect, the membrane and the member have a closed space formed by the membrane and the member on a side opposite to a side where the object of the membrane contacts. The gist.

  Therefore, according to the second aspect of the present invention, since the membrane and the member have a closed space constituted by the membrane and the member, the pressure extraction means can extract the pressure. Extraction is relatively easy.

  The invention according to claim 3 is the volume of the closed space at the arbitrary time point when the pressure extraction means obtains the pressure of the closed space at the arbitrary time point in the first or second aspect. The gist is to extract the pressure of the closed space at the arbitrary time point from the function including the physical quantities using the pressure and volume of the closed space at the time point before the time point.

  Therefore, according to the third aspect of the present invention, a dedicated device such as a pressure sensor is not required when the pressure is extracted by the pressure extracting means. Therefore, the apparatus can be further simplified and downsized.

The gist of the invention of claim 4 is that, in any one of claims 1 to 3, the volume of the closed space is a volume obtained from the shape of the film.
Therefore, according to the fourth aspect of the present invention, since the volume of the closed space can be obtained from the shape of the membrane, no means or apparatus for obtaining the volume of the closed space is required. Therefore, the apparatus can be further simplified and downsized.

  A fifth aspect of the present invention is the volume of the closed space according to any one of the first to fourth aspects, wherein the volume of the closed space is extracted by photographing a part or all of the closed space with the imaging means (4). That is the gist.

  Therefore, according to the fifth aspect of the present invention, since the volume of the closed space can be extracted by photographing with the imaging means, it is realized by a relatively small device. Therefore, the apparatus can be further simplified and downsized.

  As the “imaging means”, it is preferable to use a camera that outputs image information as an electrical signal, and it is particularly preferable to use a digital camera. Here, examples of the “digital camera” include a CCD camera and a digital camera using a C-MOS image sensor.

  A sixth aspect of the present invention is the six-axis force measuring device according to any one of the first to fifth aspects, wherein the six-axis force measuring device according to any one of the first to fifth aspects is used. A method for measuring an arbitrary axial force and moment acting on the film, the step of extracting the shape of the film by the shape extraction means, and the side on which the object of the film contacts by the pressure extraction means Extracting the pressure in the opposite space, dividing the membrane into several elements from the shape of the membrane, deriving an equation for mechanical quantities for one or more of the elements, The step of obtaining the tension acting on the membrane from the equation relating to the mechanical quantity and the pressure in the space on the opposite side, and the arbitrary acting on the six-axis force measuring device from the tension acting on the membrane and the pressure in the space on the opposite side Axial force of To include the steps of finely moments extracted as its gist.

  Therefore, according to the invention described in claim 6, the shape of the film is extracted by the shape extracting means, and then the pressure in the space opposite to the side on which the object of the film contacts is detected by the pressure extracting means. Extracting, further dividing the membrane into several elements from the shape of the membrane, and using it to derive an equation relating to the mechanical quantity for one or more of the elements, The tension acting on the membrane is obtained from the pressure in the space on the opposite side, and finally the axial force and moment acting on the six-axis force measuring device from the tension acting on the membrane and the pressure in the space on the opposite side. To extract. That is, 6-axis force can be measured by a simple device and means, and 6-axis force can be measured in real time.

The gist of the invention according to claim 7 is that, in claim 6, the formula relating to the mechanical quantity is a formula of balance of force and moment acting on the element.
Therefore, according to the seventh aspect of the present invention, since the formula relating to the mechanical quantity is a formula for balancing the force and moment acting on the element, the complicated stress-strain relationship of the film is not used. Therefore, even if the film is largely deformed or complicatedly deformed, it can be measured while maintaining measurement accuracy.

  The invention according to claim 8 is the method according to claim 6 or 7, wherein the formula relating to the mechanical quantity is obtained using information relating to a non-contact area where the film extracted by the non-contact area extraction means is not in contact with the object. The gist is that

  Therefore, according to the invention described in claim 8, the equation relating to the mechanical quantity is an equation obtained using information relating to the non-contact region where the film extracted by the non-contact region extracting means is not in contact with the object. Therefore, the formula relating to the mechanical quantity originally considers only the tension and pressure of the film with respect to the film, and the influence of the contact force caused by the contact of the object becomes a problem, but the influence can be prevented. Become.

  The invention according to a ninth aspect is the formula according to any one of the sixth to eighth aspects, wherein the formula relating to the mechanical quantity is obtained using information relating to the tension direction acting on the film obtained by the tension direction extracting means. That is the gist.

  Therefore, according to the invention described in claim 9, since the equation relating to the mechanical quantity is an equation obtained using information relating to the tension direction acting on the membrane obtained by the tension direction extracting means, It becomes possible to consider the behavior of the acting tension more accurately.

  A tenth aspect of the present invention provides the non-contact region according to any one of the sixth to ninth aspects, wherein the non-contact region extraction means includes a region included within a certain distance from a contact portion between the film and the member. The gist of this is

  Therefore, according to the invention described in claim 10, the non-contact region extracting means sets the region included within a certain distance from the contact portion of the film and the member as the non-contact region. By providing, extraction of the non-contact area can be simplified.

  An eleventh aspect of the present invention is that, in any one of the sixth to tenth aspects, the tension direction extracting means provides a marker (12) on the film, and information on the tension direction is obtained from position information of the marker. The gist is that it is a means for extraction.

  Therefore, according to the invention described in claim 11, since the tension direction acting on the membrane can be extracted by the marker provided on the membrane, a complicated device and means are not required and a relatively easy method is used. realizable.

  According to a twelfth aspect of the present invention, in any one of the sixth to eleventh aspects, the marker position information is position information of the marker extracted by photographing the marker with an imaging unit. The gist.

  Therefore, according to the twelfth aspect of the present invention, since the marker position information can be extracted by photographing with the imaging means, this is realized by a relatively small device. Therefore, the apparatus can be further simplified and downsized.

  As the “imaging means”, it is preferable to use a camera that outputs image information as an electrical signal, and it is particularly preferable to use a digital camera. Here, examples of the “digital camera” include a CCD camera and a digital camera using a C-MOS image sensor.

  According to the thirteenth aspect of the present invention, the film is deformable according to the shape of the object that is a contact portion with the object, and the film is fixed from the side opposite to the side of the film that contacts the object. A six-axis force measuring device including a member, a shape extracting means for extracting the shape of the film, and a pressure extracting means for extracting a pressure in a space opposite to the side on which the object of the film contacts, and the film The shape extracting means for extracting the shape of the film, the pressure extracting means for extracting the pressure in the space opposite to the side on which the object of the film contacts, and the film from the shape of the film into several elements A step of dividing, a membrane element dividing unit, a dynamic equation deriving unit for deriving an equation related to a mechanical quantity for one or a plurality of the elements, and Tension extracting means for determining the acting tension, and acting on the membrane A six-axis force measuring device comprising: six-axis force extracting means for extracting an arbitrary axial force and moment acting on the six-axis force measuring device from the tension and the pressure in the opposite space. The six-axis force measurement system is the gist.

  Therefore, according to the invention described in claim 13, the shape of the film is extracted by the shape extraction means, and then the pressure of the space opposite to the side on which the object of the film contacts is detected by the pressure extraction means. Extracting, further dividing the membrane into several elements from the shape of the membrane, and using it to derive an equation relating to the mechanical quantity for one or more of the elements, The tension acting on the membrane is obtained from the pressure in the space on the opposite side, and finally the axial force and moment acting on the six-axis force measuring device from the tension acting on the membrane and the pressure in the space on the opposite side. To extract. That is, 6-axis force can be measured by a simple device and means, and 6-axis force can be measured in real time.

  In the invention according to claim 14, the marker is disposed on a side opposite to the side on which the object of the film (contact part) included in the six-axis force measuring device contacts, and the object contacts the film. An optical tactile sensation comprising: a tactile information extracting means comprising: an imaging means for photographing the behavior of the marker portion at the time; and a six-axis force measuring device according to any one of claims 1 to 5 The gist of the sensor.

  Therefore, according to the invention described in claim 14, the optical tactile sensor in which the marker part is arranged in the tactile part (contact part) and the behavior is photographed by the imaging means, and the six-axis force measuring method of the present invention It is possible to combine devices. If a marker portion is arranged on the film of the shape measuring device and is photographed by an imaging means included in the shape measuring device, the function of the optical tactile sensor having the marker portion can be achieved. That is, this 6-axis force measurement method / device can be applied not only to a tactile sensor, but also to an apparatus capable of measuring a 6-axis force while maintaining the function of a conventional tactile sensor.

  A fifteenth aspect of the invention is a method for measuring a mechanical quantity and an arbitrary axial force and moment acting on the optical tactile sensor using the optical tactile sensor of the fourteenth aspect. , Measuring a mechanical quantity using the tactile information extracting means, and measuring an arbitrary axial force and moment acting on the optical tactile sensor using the six-axis force measuring method. The gist is a mechanical quantity measuring method using an optical tactile sensor characterized by the following.

  Therefore, according to the invention described in claim 15, the optical tactile sensor in which the marker part is arranged in the tactile part (contact part) and the behavior is photographed by the imaging means, and the six-axis force measuring method of the present invention It is possible to combine devices. If a marker portion is arranged on the film of the shape measuring device and is photographed by an imaging means included in the shape measuring device, the function of the optical tactile sensor having the marker portion can be achieved. That is, this 6-axis force measurement method / device can be applied not only to a tactile sensor, but also to a method that enables 6-axis force measurement while maintaining the function of a conventional tactile sensor.

Examples of the mechanical quantity include one or more selected from the group consisting of slip, coefficient of friction, shape, position of the object, and posture of the object.
(Effect of the invention)
As described above in detail, according to the first aspect of the invention, the six-axis force measuring device can be easily manufactured, and the shape measuring device can be easily downsized. In addition, the conventional optical tactile sensor system and other fields can be easily applied.

According to invention of Claim 2, when extracting a pressure by the said pressure extraction means, since it is a closed space, extraction becomes comparatively easy.
According to the invention described in claim 3, the device can be further simplified and miniaturized.

According to the fourth aspect of the present invention, the device can be further simplified and downsized.
According to the invention described in claim 5, it is possible to further simplify and miniaturize the apparatus.
According to the sixth aspect of the invention, it is possible to measure 6-axis force with a simple device and means, and it is possible to measure 6-axis force in real time.

According to the invention described in claim 7, even if the film is largely deformed or complicatedly deformed, it can be measured while maintaining measurement accuracy.
According to invention of Claim 8, it becomes possible to prevent the influence of the contact force which arises by the contact of a target object with respect to the type | formula regarding the said mechanical quantity.

According to the ninth aspect of the present invention, it is possible to more accurately consider the behavior of the tension actually acting on the film.
According to the invention described in claim 10, the extraction of the non-contact area can be simplified.

According to the invention described in claim 11, it is possible to extract the direction of tension acting on the film by a relatively easy method without requiring a complicated device or means.
According to the twelfth aspect of the present invention, the device can be further simplified and downsized.

According to the thirteenth aspect of the present invention, it is possible to measure a six-axis force with a simple device and means, and it is possible to measure a six-axis force in real time.
According to the fourteenth aspect of the present invention, a 6-axis force measurement device and a 6-axis force measurement device are applied to a tactile sensor, and a method for enabling 6-axis force measurement while maintaining the function of a conventional tactile sensor. Can be equipment.

  According to the fifteenth aspect of the present invention, a 6-axis force measurement device and a 6-axis force measurement device are applied to a tactile sensor, and a method that enables 6-axis force measurement while maintaining the function of a conventional tactile sensor. realizable.

The whole perspective view which shows the 6-axis force measuring device in this invention. The whole perspective view of the touchpad using a pressure sensor. The figure which shows the marker position which a film | membrane has. The block diagram which shows the structure of a 6-axis force measurement system. The flowchart which shows the outline of the process by a 6-axis force measurement system. The figure which shows the marker position and other symbols in the tension direction extracting means. The figure which shows the division | segmentation method of a film | membrane at the time of 6 axial force extraction, and its symbol. The whole perspective view which shows the tension | tensile_strength which acts on one film | membrane at the time of 6 axial force extraction, and its symbol. The side view which shows the tension | tensile_strength which acts on one film | membrane at the time of 6 axial force extraction, and its symbol. The side view which shows the tension | tensile_strength which acts on a some film | membrane at the time of 6 axial force extraction, and its symbol. The figure which shows the relationship of the tension | tensile_strength which acts on the edge of a film | membrane at the time of 6 axial force extraction. The figure which shows the relationship between the tension | tensile_strength which acts on the edge of a film | membrane at the time of 6-axis force extraction, and the 6-axis force which acts. The figure which shows the Z-axis direction component of force when an object comes in parallel with the Z-axis with respect to a touchpad. The figure which shows the X-axis direction component of force when an object comes in parallel with the X-axis with respect to a touchpad. The figure which shows the Z-axis direction component of force when an object comes in parallel with the X-axis with respect to a touchpad. The figure which shows the Z-axis direction component of force when an object rotates with respect to a touchpad in parallel with a Z-axis, and rotates around a Z-axis. The figure which shows the moment around a Z-axis when an object rotates with respect to a Z-axis after an object comes in parallel with a Z-axis with respect to a touchpad. The whole perspective view of the touchpad using a compressible fluid and a box. The figure which shows the dot pattern which a film | membrane has. The flowchart which shows the outline of the process by an optical touch sensor. The figure which shows the state which an operator's finger contacts with the hemispherical touchpad of a 6-axis force measuring device.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is embodied in a six-axis force measurement system will be described in detail with reference to FIGS.

As shown in FIG. 1, a touch pad 3 (contact portion) having a shape in which a flat plate and a hemisphere are joined is provided on the distal end side of a casing 2 constituting the six-axis force measuring device 1. . In the casing 2, a CCD camera 4 as an imaging means is arranged.
The CCD camera 4 is arranged on the side opposite to the side in contact with the object W1 with the touch pad 3 as the center.

  An illumination 5 is arranged in the casing 2. The illumination 5 is disposed on the touch pad 3 on the side opposite to the side in contact with the object W1. The CCD camera 4 captures images from the back side of the touch pad 3.

  As shown in FIG. 2, the touch pad 3 fixes an elastically deformable film 6 as a contact portion, a light-transmitting plate 7 in which all ends of the film 6 are in close contact, and the film 6 and the plate 7. It is comprised with the board | substrate 7 and the state which pinched | interposed the film | membrane 6 with the fixture 7.

The film 6 includes a hemispherical portion 6a and a flat plate-like portion 6b surrounding the periphery. The hemispherical portion 6a protrudes to the side in contact with the object W1 (lower side in FIG. 1).
The plate 7 is located on the “side opposite to the side in contact with the object W1” in the film 6 and is in contact with the flat plate-like portion 6b, but there is a closed space between the hemispherical portion 6a. To do.

  A tube 9 is connected to the plate 7, and a pressure sensor 10 as a pressure extracting means is connected to the other end of the tube 9. Here, the space surrounded by the membrane 6, the plate 7, the tube 9, and the pressure sensor 10 is a closed space in which traffic from outside air is blocked and is filled with the liquid 11.

As shown in FIGS. 2 and 3, a marker 12 is disposed on the side of the film 6 opposite to the side in contact with the object W <b> 1.
Here, the CCD camera 4, the illumination 5, and the liquid 11 play a role as a part of the shape extraction unit. Therefore, when using other shape extraction means, the CCD camera 4, the illumination 5, and the liquid 11 may be omitted. Further, the CCD camera 4 and the marker 12 serve as a part of the tension direction extracting means. Therefore, when other tension direction extracting means is used, the CCD camera 4 and the marker 12 need not be provided.

The CCD camera 4 is a three-channel CCD camera of red, green and blue. Any camera having two or more channels may be used, and a C-MOS camera may be used instead of a CCD camera.
As the illumination 5, coaxial epi-illumination (manufactured by CCS: LFV-50SW2) was used. In addition, a polarizing plate (made by CCS: PL-LFV-50SW2) is attached to the illumination 5 in order to prevent the component from entering the CCD camera 4 when the light emitted from the illumination 5 is reflected by the plate 7. Then, a polarizing filter was attached to the CCD camera 4. Further, the illumination 5 may be another point light source or a surface light source as long as the position where the light is irradiated (light source position) and the direction in which the light is irradiated can be known.

  It is desirable that the thickness of the film 6 be reduced to such an extent that the bending moment of the film 6 is sufficiently small compared to the force measured. The shape of the film 6 is hemispherical when viewed from the side in contact with the object W1, but may be other shapes as long as it is convex when viewed from the side in contact with the object W1. When the object W1 is not in contact with the touch pad 3, the film 6 is provided at the end of the film 6 (the boundary between the contact portions of the film 6 and the fixture 8) so that no shearing force is applied. Yes.

  The film 6 is made of a transparent silicone rubber (manufactured by Shin-Etsu Silicon: KE-1950-10) mixed with a black colorant and a black film having a thickness of 0.5 mm and a transparent silicone rubber (Shin-Etsu Silicone). -Manufactured by KE-1950-10) and a white film having a thickness of 0.5 mm formed by mixing a white colorant. Therefore, the film 6 has a black color on the side in contact with the object W1 and a white color on the opposite side.

The plate 7 is a transparent acrylic plate, but may be made of other materials as long as it is light transmissive and has a hardness that does not deform during measurement.
The fixture 8 is a metal plate having a touchpad-sized circular hole, but may be made of other materials as long as it has a hardness that does not deform during measurement.

The tube 9 is a silicone rubber tube having an inner diameter of 2 mm and an outer diameter of 4 mm. However, the tube 9 may have other shapes and materials as long as it does not change greatly with respect to the pressure change in the closed space. However, the larger the inner diameter, the better. The pressure sensor 10 is a diaphragm type pressure transducer and uses a pressure sensor with a measurement range of 0 Pa to 200 kPa in gauge pressure, but may be a sensor having other types or other measurement ranges.
The liquid 11 is red translucent water obtained by dissolving red pigment (manufactured by ZEBRA: JK-05) in tap water. However, the liquid 11 may be made of other materials as long as it is suitable for the patent document (Japanese Patent Application No. 2010-180928). May be.

  The marker 12 has a circular shape with a radius of about 0.5 mm and has a black color. However, the marker 12 has other colors and shapes as long as the position information can be acquired when the image is taken by the CCD camera 4. Also good. In addition, although 36 markers 12 are provided at equal intervals along the end of the membrane 6 (the boundary between the contact portions of the membrane 6 and the fixture 8) at a distance of about 2 mm, other markers and intervals are provided. May be.

  As shown in FIG. 4, the 6-axis force measurement system 13 including the 6-axis force measurement device 1 includes a control unit 14 that controls the entire 6-axis force measurement system 13. The control unit 14 includes a CPU 15, and a ROM 16, a RAM 17, and an input / output port (I / O port) 18 are connected to the CPU 15. The CPU 15 executes various processes for controlling the entire six-axis force measurement system 13 and outputs the processing results as predetermined control signals. The ROM 16 stores a control program for controlling the six-axis force measurement system 13 and the like. The RAM 17 temporarily stores various information necessary for the operation of the six-axis force measurement system 13. Further, the CCD camera 4, the illumination 5 and the pressure sensor 10 are connected to the input / output port 18. Image information inputted from the CCD camera 4 by photographing the touch pad 3 is inputted to the CPU 15 via the input / output port 18. At the same time, the CPU 15 outputs a signal for turning on the illumination 5 to the illumination 5 via the input / output port 18.

  The CPU 15 shown in FIG. 4 performs image processing on image information from the CCD camera 4 that is input via the input / output port 18 at regular intervals (in this embodiment, every 100 ms). Note that image information acquired at regular intervals is stored in a storage area of the RAM 17 for a certain period, and is erased sequentially from the oldest one. As the image processing software, commercially available software (manufactured by MVTec: HALCON) is used. Then, the CPU 15 extracts the shape of the film 6 and the direction of the tension acting on the end of the film 6 from the photographed image, and extracts a non-contact area where the object W1 is not in contact with the film 6 from the shape of the film 6. . Further, the CPU 15 inputs an analog signal from the pressure sensor 10 and extracts the pressure of the liquid 11. Finally, the CPU 15 calculates and extracts the 6-axis force acting on the plate 7 from these pieces of information. That is, the CPU 15 has a function as information extraction means.

Next, a method for measuring the six-axis force acting on the plate 7 by the six-axis force measurement system 13 will be described.
As shown in FIG. 5, when the touch pad 3 comes into contact with the object W1 in step S110 (step S110), contact is determined based on a change in an image taken through the touch pad 3. The CPU 15 captures image information input from the CCD camera 4 by photographing the behavior of the touch pad 3 (step S120), extracts the shape of the film 6 using the shape extracting means (step S130), and extracts the image information from the image information. The position information of the marker 12 is used to calculate the direction of tension acting on the end of the film 6 (step S140). Next, the CPU 15 extracts the non-contact area where the object W1 is not in contact with the film 6 by the non-contact area extraction means using the acquired shape information of the film 6 (step S150). And the pressure of the liquid 11 is extracted (step S160). Finally, the CPU 15 is based on the obtained shape information of the membrane 6, the direction of the tension acting on the end of the membrane 6, the non-contact area of the membrane 6 and the pressure information acting on the space between the membrane 6 and the plate 7. A six-axis force acting on the plate 7 is calculated and extracted (step S170).

As described above, by performing the processing from step S110 to step S170, the six-axis force acting on the plate 7 can be measured.
Here, a method (step S130) of extracting the shape of the film 6 from a photographed image based on an analysis of the intensity of light of two different channels captured by the camera using a single camera is disclosed in Japanese Patent Application (Patent Application (Japanese Patent Application). 2010-180928) or non-patent literature (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Shape Sensing by Vision-based Tactile Sensor for Dexterous Handling of Robot Hands” In Proceedings of 2020 IEEE Conference on Automation Science and Engineering, Aug, 2010).

The method of calculating the position information of the marker 12 using the image information and extracting the direction of the tension acting on the end of the film 6 (step S140) is as follows.
First, as shown in FIG. 6, the X, Y, and Z axes are defined with the center Q1 of the plate 7 as the origin. Next, an axis that is on the XY plane and forms an angle of 2π (i + 1/2) / N1 (rad) with the X axis is defined as U1 (i) (i = 1, 2,... N1). . N1 is the number of markers 12. Then, the position vector of the intersection of the end of the membrane 6 (the boundary between the contact portion of the membrane 6 and the fixture 8) and the U1 (i) axis is defined as E (i).
In a state where the object W1 is not in contact with the touch pad 3, the touch pad 3 maintains a hemispherical shape, and shear force acts on the end of the film 6 (boundary boundary between the film 6 and the fixture 8). Not done. Therefore, the position vector of the N1 markers 12 in this state is defined and stored as D1 (i) (i = 1, 2,... N1). Next, when the object W1 comes into contact with the touch pad 3, the position of the marker 12 changes, and the position vector of the marker 12 at this time is defined as D2 (i) (i = 1, 2,... N1). Here, the direction of the tension acting on the position of each E (i) forms an angle of ∠D1 (i) E (i) D2 (i) with respect to the vector (D1 (i) -E (i)) And let this angle be φ1 (i) (i = 1, 2,... N1). Further, the direction of tension acting on an arbitrary point D3 between E (i) and E (i + 1) on the end of the membrane 6 (boundary of the contact portion between the membrane 6 and the fixture 8) is E ( When the distance to i) is L1 (i) and the distance from that point to E (i + 1) is L2 (i), the direction of tension acting on that point is φ1 (i) and φ1 (i + 1) Is expressed by using φ2 given as follows as a linear combination.

φ2 = (φ1 (i) · L2 (i) + φ1 (i + 1) · L1 (i)) / (L1 (i) + L2 (i)) (Formula 1)
φ2 expresses an angle formed by the direction of tension when the object W1 is not in contact with the film 6 and the direction of tension when the object W1 is in contact. Therefore, the direction of tension acting on the end of the membrane 6 (the boundary between the contact portions of the membrane 6 and the fixture 8) can be expressed by φ2.

  Next, a method (step S150) for extracting a non-contact area where the object W1 is not in contact with the film 6 by the non-contact area extracting means using the acquired shape information of the film 6 is described in a non-patent document (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Acquisition of Tactile Information by Vision-based Tactile Sensor for Dexterous Handling of Robot Hands” In Proceedings of IEEE / RSJ 2010 International Conference on Intelligent Robots and Systems, Oct, 2010) By using the touch area extracting means described, a convex area is extracted as a non-contact area when viewed from the side on which the object W1 in the shape of the film 6 contacts. Further, in the region on the film 6, a region in the range of δ1 or less with respect to the Z-axis direction is also extracted as a non-contact region. In this embodiment, δ1 = 4.62 mm, but other values may be used.

  Further, when the analog signal from the pressure sensor 10 is input and the pressure of the liquid 11 is extracted (step S160), it is assumed that the pressure of the liquid 11 is constant in the entire region. That is, the liquid 11 is treated as having no body force.

  Based on the shape information of the film 6 obtained by the CPU 15, the direction of the tension acting on the edge of the film 6, the pressure information acting on the non-contact area of the film 6 and the space between the film 6 and the plate 7, A method for calculating and extracting the 6-axis force acting on the pressure 7 (step S170) is as follows.

  As shown in FIG. 7, contour lines having a constant interval δ2 with respect to the Z axis defined above are drawn on the film 6, and are sequentially drawn as A1 (1), A1 (2), A1 (3), . . . We will define In this embodiment, δ2 = 0.154 mm, but other values may be used. Next, an axis that is on the XY plane and forms an angle of 2πi / N2 (rad) with the X axis is defined as U2 (i) (i = 1, 2,... N2). In this embodiment, N2 = 72, but other values may be used. The intersection of the end of the membrane 6 (the boundary between the contact portion of the membrane 6 and the fixture 8) and the U2 (i) axis is defined as B1 (i). Here, when a line B2 (i) is drawn on the film 6 so as to intersect each A1 (i) perpendicularly from B1 (i), the Z-direction component of the slope of this line B2 (i) becomes zero. Is point B3 (i). Further, a line segment connecting B3 (i) and B3 (i + 1) is defined as A2 (i) (i = 1, 2,... N2-1), and a line connecting B3 (N2) and B3 (1). Let the minutes be A2 (N2).

  Next, the film 6 is divided into a plurality of elements. An element surrounded by four lines A1 (j), A1 (j + 1), B2 (i), and B2 (i + 1) is defined as M (i, j) (however, if i = N2 1 is inserted instead of i + 1 in the definition of Here, the contour line at the highest position in the Z-axis direction is A1 (N3 (i)) among the contour lines A1 (i) at a position lower in the Z-axis direction than A2 (i). Define to be Then, an element surrounded by four lines A1 (N3 (i)), A2 (i), B2 (i), and B2 (i + 1) is defined as M (i, N3 (i)) (however, When i = N2, 1 is inserted instead of i + 1 in the above definition).

  Next, a force balance equation is applied to each of the divided elements M (i, j) (i = 1, 2,... N2) (j = 1, 2,... N3 (i)). Stand up. As shown in FIG. 8, the tension acting on each side of the element M (i, j) is expressed as F1 (i, j), F1 (i, j + 1), F2 (i, j), F2 (i + 1, j ). Furthermore, since each element is sufficiently small, it is assumed that the point at which each tension acts acts on the midpoint of each side of the element M (i, j).

  Here, considering the shear force acting on each element, generally the shear force acts almost symmetrically on each element, and the shear component of the tension F2 is difficult to act structurally. Approximate 0. By this approximation, the direction of the tension F2 is a direction parallel to the contour line A1, that is, a direction perpendicular to the Z axis.

  Using these assumptions and approximations, consider FIG. 9 where each element M (i, j) is projected onto the U3 (i) -Z plane, where U3 (i) (i = 1, 2,... N2 ) Is defined on the XY plane as an axis that forms an angle of 2π (i + 1/2) / N2 (rad) with the X axis. When M (i, j) is projected onto the U3 (i) -Z plane, the U3 (i) -Z plane components of F1 (i, j) and F1 (i, j + 1) are respectively F3 (i, j) and F3 (i, j + 1) is assumed, and the resultant force of F2 (i, j) and F2 (i + 1, j) is assumed to be F4 (i, j). At this time, F4 (i, j) has only a U3 (i) direction component because it operates in a direction perpendicular to the Z-axis by the above approximation. As described above, the balance equations in the Z direction and the U3 (i) direction are given by the following (Expression 2) and (Expression 3), respectively.

F3 (i, j + 1) · sinΘ (i, j + 1) = F3 (i, j) · sinΘ (i, j) −P · S1 (i, j) (Formula 2)
F4 (i, j) = F3 (i, j) .cos.THETA. (I, j) -F3 (i, j + 1) .cos.THETA. (I, j + 1) + P.S2 (i, j) (Formula 3)
Here, P is the pressure acting on the space between the membrane 6 and the plate 7, and S1 (i, j) is the area when the element M (i, j) is projected onto a plane perpendicular to the Z axis. S2 (i, j) is an area when the element M (i, j) is projected onto a plane perpendicular to the U3 (i) axis. Θ (i, j) and Θ (i, j + 1) are angles with respect to the U3 (i) axis at both ends of the element M (i, j) as shown in FIG. Further, S1 (i, j), S2 (i, j), Θ (i, j), and Θ (i, j + 1) can be acquired based on the shape information of the film 6 obtained by the shape extracting means. The pressure P is acquired by the pressure sensor 10.

  Next, as shown in FIG. 10, the elements M (i, j) (j = 1, 2,... N3 (i)) are combined and considered as one element. Here, N3 (i) is an element in a non-contact area where M (i, j) (j = 1, 2,... N3 (i)) is not in contact with the object W1, and M (i, N3 (i) +1) is defined to be an element in the contact area. Here, the non-contact area and the contact area are areas extracted by using a non-contact area extraction unit. As shown in FIG. 10, with respect to elements obtained by combining M (i, j) (j = 1, 2,... N3 (i)), the balance equations in the Z direction and U3 (i) direction are respectively It is given by (Equation 4) and (Equation 5).

F3 (i, N3 (i) +1) · sinΘ (i, N3 (i) +1) = F3 (i, 1) · sinΘ (i, 1) −P · (S1 (i, 1) + S1 (i, 2) ) + ... + S1 (i, N3 (i))) (Equation 4)
F4 (i, 1) + F4 (i, 2) +. . . + F4 (i, N3 (i)) = F3 (i, 1) .cos.THETA. (I, 1) -F3 (i, N3 (i) +1) .cos.THETA. (I, N3 (i) +1) + P. (S2 ( i, 1) + S2 (i, 2) + ... + S2 (i, N3 (i))) (Equation 5)
Further, by simultaneously solving (Equation 2) and (Equation 3), F4 (i, j) (j = 1, 2,... N3 (i)) and F3 (i, 1) are known numbers. The following (formula 6) can be expressed by P, S1, and Θ.

F4 (i, j) = (sinΘ (i, 1) / tanΘ (i, j) −sinΘ (i, 1) / tanΘ (i, j + 1)) · F3 (i, 1) + P · (1 / tanΘ ( i, j + 1) · (S1 (i, 1) + S1 (i, 2) +... + S1 (i, j)) − 1 / tan Θ (i, j) · (S1 (i, 1) + S1 (i, 2) + ... + S1 (i, j-1)) + S2 (i, j)) (j = 1, 2,... N3 (i)) (Equation 6)
Next, the balance of moments on the U3 (i) -Z plane will be considered with the point C1 at which F3 (i, N3 (i) +1) acts as a fulcrum. In order to derive the moment balance, it is necessary to obtain the distance between the point of action of each force acting on the element and the point C1. F4 (i, j) (j = 1, 2,... N3 (i)) is perpendicular to the Z axis and acts on the midpoint of the side of the element M (i, j). Therefore, the distance L3 (i, j) from the operating point of F4 (i, j) to the point C1 is given by the following (Expression 7).

L3 (i, j) = δ2 · (N3 (i) −i + 1/2) (Formula 7)
From (Expression 7), the balance of moments on the U3 (i) -Z plane with the point C1 as a fulcrum is given by the following (Expression 8).
L4 (i, j) .F5 (i, 1) = (L3 (i, 1) .F4 (i, 1) -L5 (i, 1) .P.S1 (i, 1) -L6 (i, 1) P.S2 (i, 1)) + (L3 (i, 2) .F4 (i, 2) -L5 (i, 2) .P.S1 (i, 2) -L6 (i, 2). P · S2 (i, 2)) +. . . + (L3 (i, N3 (i)). F4 (i, N3 (i))-L5 (i, N3 (i)). P.S1 (i, N3 (i))-L6 (i, N3 ( i)) · P · S2 (i, N3 (i))) (Equation 8)
Here, F5 (i, 1) is a vector including the direction of the scalar F3 (i, 1), and L4 (i, j) is a point from the point C1 to the action point of F5 (i, 1). Is a vector. L5 (i, j) is the distance of the U3 (i) direction component from the point C1 to the center of gravity of the element M (i, j), and L6 (i, j) is the element M (i, j) from the point C1. The distance of the Z direction component to the center of gravity position. L4 (i, j), L5 (i, j) and L6 (i, j) can be acquired based on the shape information of the film 6 obtained by the shape extraction means, and F5 (i, 1) is F3. It can be acquired based on (i, 1) and the shape information of the film 6.

  By the above derivation, (Equation 4), (Equation 5), (Equation 6), and (Equation 8) are combined, and F5 (i, 1) (i = 1) that is the tension acting on the end of the film 6 , 2, ... N2) can be obtained algebraically. However, F5 (i, 1) (i = 1, 2,... N2) is a component on the U3 (i) -Z plane of the tension acting on the end of the film 6, that is, a shear direction component is included. Absent. Here, as shown in FIG. 11, by using φ2 representing the direction of tension acting on the end of the membrane 6 (the boundary between the contact portions of the membrane 6 and the fixture 8), a shear direction tension vector F6 (i ) Is given by the following (Equation 9).

F6 (i) = (F3 (i, 1) · cosΘ (i, 1) · tanφ3) (Equation 9)
However, φ3 is an angle when the angle φ2 is projected onto the XY plane. Further, it is assumed that the direction of the tension vector F6 (i) is perpendicular to the U3 (i) axis and the Z axis. Therefore, the tension vector F7 (i) acting on the end of the film 6 including the shear direction component is expressed as the following (Equation 10).

F7 (i) = F5 (i, 1) + F6 (i) (Formula 10)
Finally, using the tension vector F7 (i) (i = 1, 2,... N2) acting on the end of the derived film 6 and the pressure P, the center Q1 of the plate 7 acts on the 6-axis force. Is calculated and extracted.

F8 = F7 (1) + F7 (2) +. . . + F7 (N2) + P · S3 (Formula 11)
M1 = L7 (1) .F7 (1) + L7 (2) .F7 (2) +. . . + L7 (N2) · F7 (N2) (Formula 12)
Here, F8 is a force vector (X, Y, Z axis direction component) acting on the center Q1 of the plate 7, and M1 is a moment vector (components around the X, Y, Z axes) acting on the center Q1 of the plate 7. is there. L7 (i) (i = 1, 2,... N2) is a vector from Q1 to the action point of F7 (i) as shown in FIG. S3 is the area of the region where the liquid 11 is in contact with the plate 7.

Through the above process, the extraction of the six-axis force is completed for the center Q1 of the plate 7 to act.
Therefore, according to the present embodiment, the following effects can be obtained.
(1) The six-axis force measuring device 1 and the six-axis force measuring system 13 of the present embodiment are composed of four touch pads 3, a CCD camera 4, an illumination 5 and a pressure sensor 10, which are relatively small. It can be processed with a simple structure. It can be applied relatively easily when applied to an optical tactile sensor mounted on a robot and other fields.

(2) In the present embodiment, six-axis forces acting on the touch pad 3 can be extracted, so that the present invention can also be applied in fields requiring multidimensional force information.
(3) In this embodiment, since the touch pad 3 is composed of the elastic film 6 and the plate 7 and the liquid 11 filling the space between them, the touch pad 3 is easy to become familiar with the object W1 and is sufficient for contact. A contact area can be secured. Therefore, application to a part that maintains stable contact with the object W1, such as a fingertip of a robot hand, is also possible.

  (4) In this embodiment, the relationship between the stress and strain of the elastic body is very complicated. However, since the 6-axis force can be extracted without using this relationship, the elastic body is greatly deformed or complicated. Even in the case of deformation, 6-axis force can be extracted without being relatively affected by the influence.

(5) In the present embodiment, it is considered that the measurement by the six-axis force measurement system 13 can achieve practical accuracy. FIG. 13, FIG. 14, FIG. 15, FIG. 16 and FIG. 17 show the measurement results of the force acting on the plate 7 by the six-axis force measurement system 13. FIG. FIG. 13 shows the Z-axis direction component of the force acting on the plate 7 when the object W1 comes into contact with the touch pad 3 in parallel with the Z-axis, and the maximum error is about 0.8N. 14 and 15 show the X-axis direction component and the Z-axis direction component of the force acting on the plate 7 when the object W1 comes into contact with the touch pad 3 in parallel with the X-axis, and the maximum error is They are about 0.8N and 0.7N, respectively. 16 and 17 show the Z-axis direction component of the force acting on the plate 7 and the Z-axis direction when the object W1 rotates around the Z-axis after contacting the touchpad 3 in parallel with the Z-axis. The maximum error is about 1N and 4Nmm, respectively. The cause of these errors is thought to be that errors in the subsequent force extraction were caused by the measurement error of the shape of the film 6 obtained by the shape measuring means. Therefore, it is considered that the measurement accuracy of the six-axis force is improved by improving the measurement accuracy of the shape measuring means by increasing the spatial resolution of the CCD camera 4 or the like. From the above results, it is shown that the measurement by the 6-axis force measurement system 13 can sufficiently achieve practical accuracy.
[Second Embodiment]
Next, a second embodiment will be described based on FIGS. In addition, about the location which is common in 1st Embodiment, the detailed description is abbreviate | omitted instead of attaching | subjecting the same number.
This embodiment is an embodiment in which the extraction of the pressure of the liquid 11 in the first embodiment (step S160) is performed by another method.

In the touch pad 3, as shown in FIG. 18, instead of the pressure sensor 10, a box 20 in which a compressive fluid 19 is enclosed is attached.
Here, the connection portion between the tube 9 and the box 20 can move the liquid 11, but the tube cannot be moved to the extent that the compressible fluid 19 passes through the tube 9 and enters the opposite side due to the change in the posture of the touch pad 3. 9 is narrowed. The box 20 is sealed so that the compressive fluid 19 cannot move with respect to the outside air.

  Next, the method for extracting the pressure of the liquid 11 in the present embodiment is as follows. (Step S160) At a certain time T1, the volume of the compressive fluid 19 enclosed in the box 20 is set to V1, the pressure of the liquid 11 at that time is set to P1, and P1 is measured in advance. Next, assuming that the volume of the compressive fluid 19 at an arbitrary time T2 after that is V2, and the pressure of the liquid 11 at that time is P2, P2 is given by the function G1 of P1, V1, and V2.

In the present embodiment, the function G1 is derived using the following Boyle's law (Equation 13) or Van der Waals equation (Equation 14).
P2 = P1 · V1 / V2 (Formula 13)
(P2 + H1 / V2) * (V2-H2) = (P1 + H1 / V1) * (V1-H2) (Formula 14)
Here, H1 and H2 are coefficients, and can be identified in advance using actually measured values. Alternatively, a function estimated in advance using actually measured values may be used as the function G1.

  Next, in the pressure extraction method described above, the methods for obtaining the volumes V1 and V2 are as described below for the first method and the second method. Here, the volume at time T1 of the space surrounded by the membrane 6, the plate 7, the tube 9 and the box 20 is V3, and the volume at time T2 is V4.

As a first method, the following relational expression (Formula 15) is established by making the liquid 11 an incompressible fluid.
V3-V1 = V4-V2 (Formula 15)
Therefore, by measuring V1 in advance from (Equation 15), the volume V2 at an arbitrary time T2 is extracted.

Next, as a second method, the box 20 is made of a light-transmitting material, and the color of the compressive fluid 19 is different from that of the liquid 11, so that the inside of the box 20 is photographed by the CCD camera 4, By performing image processing, V1 and V2 can be estimated at arbitrary times T1 and T2.
Therefore, according to the present embodiment, the following effects can be obtained.

(1) In the six-axis force measuring device 1 and the six-axis force measuring system 13 of the present embodiment, the pressure of the liquid 11 is extracted without using the pressure sensor 10, and thus the structure of the six-axis force measuring device 1 is further simplified. This is advantageous in terms of miniaturization.
[Third Embodiment]
Next, a third embodiment will be described based on FIGS.

In addition, about the location which is common in 1st or 2nd embodiment, the detailed description is abbreviate | omitted instead of attaching | subjecting the same number.
The present embodiment is a system in which the first or second embodiment is applied to an optical tactile sensor.

As shown in FIG. 19, a dot pattern 21 as a marker portion is arranged on the opposite side of the hemispherical portion of the film 6 from the side in contact with the object W1.
Here, the dot pattern 21 may be another pattern such as a lattice pattern, a triangular mesh pattern, or a hexagonal mesh pattern (honeycomb pattern).

  As a result, the 6-axis force measurement device 1 is combined with a mechanical quantity extraction device and a mechanical quantity extraction method including the film on which the marker portion (12) is arranged and the imaging means in a state in which the 6-axis force measurement system 13 is enabled. It is also established as an optical tactile sensor 22.

  In the present embodiment, the mechanical quantity extraction device and the mechanical quantity extraction method use the optical tactile sensor described in the patent document (Japanese Patent Application No. 2005-257343 public information) and the sensing method using the optical tactile sensor. A quantity extraction device and a mechanical quantity extraction method may be used.

Next, a method for simultaneously measuring six-axis forces and other tactile information by the optical tactile sensor 22 will be described.
As shown in FIG. 20, when the touch pad 3 touches the object W1 in step S180, the CPU 15 captures image information input from the CCD camera 4 by photographing the behavior of the touch pad 3 (step S190). Image processing is performed (step S200). Next, the CPU 15 extracts tactile information from the behavior of the dot pattern 21 (step S210). Then, the CPU 15 extracts a six-axis force that acts on the plate 7 by the same method as steps S130 to S170 using the acquired image (step S220).

  As an example of extracting tactile information in step S200 and step S210, contact force and slip can be extracted by the tactile information extracting means described in the patent document (Japanese Patent Application No. 2005-257343 Public Information). 180928) or non-patent literature (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Shape Sensing by Vision-based Tactile Sensor for Dexterous Handling of Robot Hands” In Proceedings of 2020 IEEE Conference on Automation Science and Engineering , Aug, 2010), the shape information of the object W1 can be extracted. Non-patent literature (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Acquisition of Tactile Information by Vision-based Tactile Sensor for Dexterous Handling of Robot Hands ”In Proceedings of IEEE / RSJ 2010 International Conference on Intelligent Robots and Systems, Oct, 2010) By using the body posture extraction means, the contact region and between the object W1 and touchpad 3, information about the position and angle change of the touch pad 3 of the object W1 can be extracted.

Through the above steps 180 to 220, the 6-axis force and other tactile information can be simultaneously measured by the optical tactile sensor 22.
Therefore, according to the present embodiment, the following effects can be obtained.

(1) The six-axis force measuring device 1 and the six-axis force measuring system 13 of the present embodiment are configured by the touch pad 3, the CCD camera 4, the illumination 5, the tube 9, and the pressure sensor 10, and are relatively small. It can be processed with a simple structure. Therefore, when combined with a conventional optical tactile sensor system or applied to other fields, it can be applied more easily than other six-axis force measuring devices. For example, by arranging the marker portion on the film 6, it is possible to combine the optical tactile sensor that captures its behavior with the imaging means and the six-axis force measuring method / device of the present invention. That is, this 6-axis force measurement method / device can be applied not only to a tactile sensor, but also to an apparatus and system that enable 6-axis force measurement while maintaining the function of a conventional tactile sensor.
[Fourth Embodiment]
Next, a fourth embodiment will be described based on FIGS.

In addition, about the location which is common in 1st, 2nd or 3rd embodiment, the detailed description is abbreviate | omitted instead of attaching | subjecting the same number.
The present embodiment is a system in which the first, second, or third embodiment is applied to a human interface.

  FIG. 21 shows a human interface 22 in which the operator's finger W2 comes into contact with the hemispherical portion of the film 6 included in the touch pad 3 of the six-axis force measuring device 1. When the finger W2 is in contact with the touch pad 3, by using the same method as in the first, second, or third embodiment, the six-axis force acting on the touch pad 3 and the finger W2, the touch pad 3 And the shape of the finger W2, the contact area between the touch pad 3 and the finger W2, the information regarding the slip between the touch pad 3 and the finger W2, the information regarding the change in the position and angle of the finger W2 with respect to the touch pad 3. As a result, various information that the operator acts on is transmitted to various devices via the touch pad 3.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) Since the human interface 22 of the present embodiment is configured only by the six-axis force measuring device 1, it can be processed with a relatively small and simple structure. In addition, the flexibility of the touch pad 3 makes it easy to become familiar with the operator. And many information, such as 6 axial force which an operator acts, a shape, a contact area, a slip, a change of a position and an angle, can be transmitted, and many information can be transmitted to various apparatuses. Therefore, since it has more functions than conventional human interfaces such as a mouse, a touch panel, a touch pen, and a joystick, more flexible and comfortable information transmission is expected.
In addition, you may change embodiment of this invention as follows.

  In each of the above embodiments, the film 6 is formed by bonding two different color films, but may be a single color film as long as the light blocking property is strong. Further, the film is not particularly colored, but it may be colored.

  -In each said embodiment, although the illumination 5 was coaxial epi-illumination, if the position (light source position) where light is irradiated and the direction where light is irradiated is known, other point light sources and surface light sources may be used. There may be.

  In each of the above embodiments, the shape of the touch pad 3 has a shape in which a plate and a hemisphere are bonded to each other. However, the liquid 11 can be sealed inside, and the film 6 can be seen from the CCD camera 4 so as not to overlap. The shape may be acceptable.

  In each of the above embodiments, as a shape extraction means, a patent document (Japanese Patent Application No. 2010-180928) or a non-patent document (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Shape Sensing by Vision-based Tactile Sensor” For Dexterous Handling of Robot Hands ”In Proceedings of 2020 IEEE Conference on Automation Science and Engineering, Aug, 2010), the shape extraction means is used, but other methods may be used as long as the shape of the film 6 can be extracted. .

In each of the above-described embodiments, the pressure sensor 10, the box 20, or the CCD camera 4 is used as the pressure extraction unit, but other methods may be used as long as the pressure of the liquid 11 can be extracted.
In each of the above embodiments, non-patent documents (Y. Ito, Y. Kim, C. Nagai and G. Obinata, “Acquisition of Tactile Information by Vision-based Tactile Sensor for Dexterous Handling of Robot Hands The non-contact area extraction means described in “In Proceedings of IEEE / RSJ 2010 International Conference on Intelligent Robots and Systems, Oct, 2010) was used, but other methods can be used as long as the non-contact area of the membrane 6 can be extracted. good.
(Industrial applicability)
For example, if the 6-axis force measurement system of the present invention is used, the contact portion is made of an elastic body and a liquid, and multidimensional force can be measured. Application to is expected. In addition, since the 6-axis force measuring device has a relatively simple structure and requires a small amount of constituent materials, it can be applied in combination with, for example, a tactile sensor using an elastic body and an imaging means. Furthermore, since the 6-axis force measuring device can be expected to be further miniaturized due to the simplicity of the structure, and the contact portion is easily adapted, it can be applied to the medical field. By mounting on the distal end of the endoscope, it is possible to extract information on contact force from the inside of the human body, and there is a possibility that it can also be applied to the fingertips of surgical robots, contact parts of cancer screening instruments, etc. is there. In addition, taking advantage of the ability to extract multidimensional force information, it can also be applied to the operation unit of various devices as a human interface.

DESCRIPTION OF SYMBOLS 1 ... Shape measuring apparatus 2 ... Case 3 ... Touch pad 4 as a contact part ... CCD camera 5 ... Illumination 6 ... Film 7 as a contact part ... Plate 8 ... Metal plate 9 as a fixture ... Pipe 10 ... Pressure sensor DESCRIPTION OF SYMBOLS 11 ... Liquid 12 as light attenuating means ... Marker 13 for extracting tension direction ... 6-axis force measurement system 19 ... Compressible fluid 20 ... Box 21 ... Dot pattern 22 ... Human interface W1 ... Object W2 ... Operator's finger

Claims (15)

A film (6) that is deformable according to the shape of the object that is a contact portion with the object;
Members (7, 8) for holding the film from the side opposite to the side on which the object of the film contacts;
Shape extraction means (4, 5, 11) for extracting information on the shape of the film;
Pressure extraction means (10, 19, 20) for extracting information on the pressure of the space on the side opposite to the side in contact with the object when the film is used as a reference;
Force measuring means for measuring information on force using information on the shape of the membrane and information on the pressure;
A six-axis force measuring device comprising:   The six-axis force measuring device according to claim 1, wherein the space is a closed space constituted by the film and the member. When the pressure extraction means obtains the pressure of the closed space at an arbitrary time, the volume of the closed space at the arbitrary time and the pressure and volume of the closed space at a time before the arbitrary time are calculated. The 6-axis force measuring device according to claim 2, wherein the pressure in the closed space at the arbitrary time is extracted from a function including those physical quantities. The six-axis force measuring device according to claim 2 or 3, wherein the volume of the closed space is a volume obtained from the shape of the film. An imaging means capable of imaging part or all of the film;
The six-axis force measuring device according to any one of claims 2 to 4, wherein the volume of the closed space is a volume extracted from a part or all of the film imaged by the imaging means. . A six-axis force measuring method for measuring an arbitrary axial force and moment acting on the six-axis force measuring device using the six-axis force measuring device according to any one of claims 1 to 5. And
Extracting the shape of the film by the shape extraction means;
Extracting the pressure of the space by the pressure extraction means;
Dividing the membrane into several elements from the shape of the membrane;
Deriving an equation relating to a mechanical quantity for one or more of the elements;
Obtaining a tension acting on the membrane from the equation relating to the mechanical quantity and the pressure in the space;
A method for measuring a six-axis force, comprising: extracting an arbitrary axial force and moment acting on the six-axis force measuring device from the tension acting on the membrane and the pressure in the space. The six-axis force measurement method according to claim 6, wherein the formula relating to the mechanical quantity is a formula of balance of force and moment acting on the element. Extracting information about a non-contact area where the film is not in contact with an object based on the shape of the film;
The six-axis force measuring method according to claim 6 or 7, wherein the formula related to the mechanical quantity is a formula obtained using information related to a non-contact area where the film is not in contact with an object. The 6-axis force measurement according to claim 8, wherein in the step of extracting information about the non-contact area, an area included within a certain distance from the contact portion between the film and the member is set as the non-contact area. Method. Extracting information regarding the direction of tension acting on the membrane,
The six-axis force measuring method according to claim 6 or 7, wherein the formula related to the mechanical quantity is a formula obtained using information related to a direction of tension acting on the film. The step of extracting information on the direction of tension acting on the film is a step of extracting information on the direction of tension from position information of a marker (12) provided on the film. 6-axis force measurement method. The six-axis force measurement method according to claim 11, wherein the marker position information is position information of the marker extracted by photographing the marker with an imaging unit. The 6-axis force measuring device according to any one of claims 1 to 5,
Membrane element dividing means for dividing the membrane into several elements from the shape of the membrane;
Dynamic equation deriving means for deriving an equation relating to a dynamic quantity for one or a plurality of the elements;
A tension extracting means for obtaining a tension acting on the membrane from the equation relating to the mechanical quantity and the pressure of the space on the opposite side;
6-axis force extracting means for extracting an arbitrary axial force and moment acting on the 6-axis force measuring device from the tension acting on the membrane and the pressure in the space on the opposite side; Force measurement system. The 6-axis force measuring device according to any one of claims 1 to 5,
Among the films, a marker portion disposed on the opposite surface,
Marker part imaging means for photographing the behavior of the marker part when an object comes into contact with the film;
Means for obtaining three-dimensional shape information by analyzing light intensity;
An optical tactile sensor comprising: tactile information extracting means for extracting tactile information by analyzing light brightness. A mechanical quantity measuring method for measuring a mechanical quantity and an arbitrary axial force and moment acting on the optical tactile sensor using the optical tactile sensor according to claim 14,
Measuring mechanical quantities using the tactile information extracting means;
And measuring an arbitrary axial force and moment acting on the optical tactile sensor using the six-axis force measuring device.