JP6719756B2 - Body part contact force sensor - Google Patents

Description

The present invention relates to a body part contact force sensor that measures a contact force acting on a contact part in a state where a part of the body such as a finger of a measurement target person is in direct contact with a predetermined object.

When a robot hand imitating a human hand is used to perform the same work as a human hand, such as an operation of grasping and carrying a soft object or rotating and opening and closing a bottle cap. Teaching to memorize the movement of is required in advance. At the time of this teaching, for example, in order to set the force adjustment for grasping the object so as not to destroy the object in the robot, it is necessary to acquire the force adjustment when a human performs the same work as accurate data. Furthermore, for example, when developing a device that automatically detects the texture of clothes, etc., the human sense of moving the surface of the clothes with the fingertips and the contact force acting on the fingertips corresponding to the texture of the clothes It is necessary to construct a database in which the data and the data are associated with each other, and in this case as well, it is necessary to obtain accurate data of the contact force when the human finger touches the clothes. In addition, in order to develop various devices in consideration of the coexistence of humans and robots, it is necessary to accurately detect the contact force when not only the human finger but also other body parts contact the object.

BACKGROUND ART Conventionally, various force sensors have been proposed for measuring a force acting on a human finger when a human performs a predetermined motion while gripping an object. An example of this force sensor is a finger sack type force sensor proposed in Patent Document 1. This force sensor measures the force acting on the finger sack with the fingertip inserted into the finger sack existing inside the tubular finger cover. However, in this force sensor, the entire surface of the fingertip is covered with two kinds of members, a finger cover and a finger sack, and the user contacts an object through the finger cover and the finger sack. As a result, the fingertip cannot directly contact the object. Therefore, if you do not get the feeling that your fingertips are in direct contact with an object and there is a need to measure the contact force acting on the contact surface with the contact surface of the fingertip in direct contact with the object, use it. I can't.

Here, Patent Document 2 discloses a contact force detection sensor that is attached to a fingertip so that the contact force acting on the contact surface can be detected in a state where the contact surface of the ball of the fingertip is in direct contact with an object. This contact force detection sensor, a strain sensor is attached to the arm that is mounted so as to straddle the fingertip, based on the detection value of the strain sensor corresponding to the deformation of the fingertip when the fingertip touches the object, the contact force It is designed to detect. That is, in this contact force detection sensor, when the contact surface is displaced when the object is pressed by the finger, the side surface of the fingertip is displaced accordingly, and the strain sensor measures the displacement amount in the width direction of the fingertip side surface. By doing so, the contact force can be derived from the preset relationship between the displacement amount and the contact force in the state where the contact surface is in direct contact with the object.

JP, 2008-32511, A JP, 2013-3782, A

However, in the contact force detection sensor of Patent Document 2, since the contact force of the fingertip on the object is derived from the measurement of the displacement amount on the side surface of the fingertip, the state of the force acting on the contact surface of the fingertip is accurately determined. Cannot be detected. That is, the contact force is not uniquely determined from the amount of displacement of the side surface of the fingertip in the width direction of the finger, and an accurate value cannot be obtained unless various conditions are taken into consideration. For example, when a contact force acting as a reaction force in the direction perpendicular to the contact surface acts, such as when the object is simply pressed with the fingertip, and when the object is stroked with the fingertip, the contact surface is touched. Even when the contact force is different in magnitude or direction, such as when a contact force acting as a shearing force is applied along the same direction, it is possible that the displacement amount of the fingertip side surface in the width direction is the same. .. Therefore, in the example here, the contact force cannot be accurately measured unless either case is specified. In addition, before use, it is necessary to perform calibration for correcting the data of the relationship between the displacement amount and the contact force, which is stored in advance, for each user, which is troublesome.

The present invention has been devised by focusing on such a problem, and its purpose is to act on a contact portion of a body part such as a finger of a measurement target person in a state of being in direct contact with a predetermined object. It is an object of the present invention to provide a body part contact force sensor capable of accurately and easily measuring a contact force.

In order to achieve the above-mentioned object, the present invention mainly relates to a body part contact force sensor for measuring a contact force acting on a contact part of a body part of a measurement target person when the part contacts a predetermined object. The sensor body includes a sensor body that detects a state when a peripheral portion of the contact portion is deformed by the contact force, and a processing unit that obtains the contact force based on a detection result of the sensor body. A contact member that is arranged so that it can be contacted with a portion and that is pressed by the deformation of the peripheral portion, and force measuring means for measuring the magnitude of the pressing force of each component acting on the contact member in the directions of the three orthogonal axes. In the processing means, from the measurement result of the force measuring means, using each component of each pressing force acting on the contact member, the magnitude of the contact force is calculated by each component. Is adopted.

In the claims and the specification, “left”, “right”, “top”, “bottom”, “front”, and “rear” when indicating a position or direction, unless otherwise specified, It means the position or direction of the fingertip with reference to the orientation of FIG. That is, “left” and “right” mean “left” and “right” in FIG. 2, which are on both sides in the width direction of the finger, and “upper” and “bottom” are on both sides in the thickness direction of the finger. Inside means “upper” and “lower”, and “front” and “rear” mean “front” and “rear” on both sides in the finger length direction, that is, the direction orthogonal to the paper surface of FIG. The front side in the figure is referred to as "front".

ADVANTAGE OF THE INVENTION According to this invention, the force of each component of the said direction is synthesize|combined based on the measurement of the pressing force of the orthogonal 3 axial directions which acts on the contact member arrange|positioned so that the peripheral part except the contact part of a body part can be contacted. Then, since the magnitude of the contact force in the directions of the three orthogonal axes is obtained, the magnitude of the contact force can be accurately obtained. In addition, since the contact force in the orthogonal three-axis directions is obtained from the force acting on the contact member only by a dynamic calculation, a pre-calibration such as the above-mentioned Patent Document 2 for establishing the correspondence between the data is performed. Is unnecessary, and the contact force of the fingertip can be easily obtained only by mounting the sensor body on the fingertip. In this way, if the magnitude of the contact force is known for each of the components in the directions of the three orthogonal axes, it is possible to know the type of contact motion with respect to the object, and also the moment when the finger is horizontally rotated while contacting the object. Easy to find.

The schematic block diagram of the body part contact force sensor concerning this embodiment. The schematic sectional front view of a sensor main body.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a body part contact force sensor according to the present embodiment. In the figure, the body part contact force sensor 10 is a sensor that measures the contact force acting on the contact portion of the fingertip when the fingertip of the measurement target person contacts a predetermined object. Specifically, the contact force is based on the deformed state of the side surface of the finger (hereinafter, simply referred to as “finger side surface”), which is the peripheral portion except for the contact portion, which is the belly part of the fingertip. I'm supposed to ask.

The fingertip contact force sensor 10 includes a sensor body 11 that detects a deformed state of the side surface of the finger due to the action of the contact force, and a processing unit 12 that obtains the contact force based on the detection result of the sensor body 11.

As shown in FIG. 2, the sensor body 11 is attached to a fingertip so as to surround a region of the finger T on the nail T2 side except the contact portion T1. The sensor main body 11 includes a holder 14 having a substantially inverted U-shape when viewed from the front, a contact member 15 attached to two inner surfaces of the holder 14 so as to be in contact with the left and right finger side surfaces, and a finger side surface. The force measuring means 16 for measuring the pressing force applied to the contact member 15 by the deformation is provided.

The holder 14 is formed so that the sensor main body 11 can be attached to and detached from the finger T while elastically deforming. When the sensor main body 11 is attached to the finger T, the contact members 15 on both left and right sides are touched by the fingers. It is sized to abut each side.

The contact member 15 is formed of an elastic body that is elastically deformable when the abutting finger side surface is deformed so as to bulge outward by the action of the contact force of the contact portion T1, and is not particularly limited. Although not present, it is made of a material that does not prevent the magnetic sensor 19 described later from detecting a change in magnetic field, such as a urethane material or a silicon material.

The force measuring means 16 includes a magnetic body 18 embedded in the contact member 15, and a magnetic sensor 19 fixedly arranged so as to face the magnetic body 18 and detecting a change in a magnetic field between the magnetic body 18 and the magnetic body 18. It is composed by.

Although the magnetic body 18 is formed of a permanent magnet, various magnetic bodies and magnetic field generators may be used as long as they generate a magnetic field of a predetermined magnitude with the magnetic sensor 19. The magnetic body 18 is fixed inside the contact member 15, and is displaced by elastic deformation of the contact member 15.

Although not shown, the magnetic sensor 19 has a known structure including a magnetic detection element including a Hall element or a magnetic resistance element, and a substrate to which the magnetic detection element is electrically connected. The structure is such that it is converted into an electric signal corresponding to the magnitude of the magnetic field with the magnetic body 18 via the contact member 15. In addition, since the magnetic detection element can detect the magnitude of the pressing force in each of the three orthogonal directions (x, y, z axes in FIG. 2) acting on the contact member 15 due to the deformation of the side surface of the finger, It should be understood that three sets are provided as one set, and in FIG. 2, they are collectively illustrated as a single rectangular parallelepiped.

With the sensor body 11 having the above configuration, the deformed state of the left and right sides of the finger side surface is detected as follows. That is, when the contact portion T1 of the ball of the fingertip comes into contact with the predetermined object B, the side surface of the finger is deformed so as to bulge outward along with the contact. As a result, the contact member 15 that comes into contact with each of the two left and right positions on the side surface of the finger is pressed, and the contact member 15 is elastically deformed. As a result, the magnetic body 18 integrated with the contact member 15 is displaced, and the relative positional relationship between the magnetic sensor 19 and the magnetic body 18, which are fixedly arranged, changes. As a result, the magnitude of the magnetic field detected by the magnetic sensor 19 changes, and an electric signal at the magnetic sensor 19 corresponding to the pressing force from the side surface of the finger to each contact member 15 is generated.

Note that the force measuring unit 16 is not limited to the above-described configuration as long as it can detect the pressing force acting on the contact member 15 in the directions of the three orthogonal axes, and another sensor or the like can be used.

The processing unit 12 has one function incorporated in a computer, and a device including the computer is electrically connected to the magnetic sensor 19 by wire or wirelessly. This device is not particularly limited, but is provided so as to be attachable to a part of the body such as the wrist of the measurement target person, for example. Note that the computer of the mobile terminal may be provided with the function of the processing means 12 so that the person to be measured can carry it.

As shown in FIG. 1, the processing means 12 includes a force detection unit 21 for detecting the magnitude of the pressing force acting on the contact members 15 on the left and right sides, and a force detection unit 21, based on the electric signal from the magnetic sensor 19. The contact force calculator 22 is configured to calculate the contact force at the contact portion T1 of the fingertip from the detected values of the pressing forces on the left and right sides detected by the detector 21.

In the force detection unit 21, the pressing force on the finger side faces at the two left and right positions is derived for each component in the directions of the three orthogonal axes by converting the electric signal from the magnetic sensor 19.

In the contact force calculation unit 22, as shown by the following equation, the contact forces of the respective components are integrated by summing up the respective components of the pressing force of the left and right finger side faces detected by the force processing means 21 in the directions of the three orthogonal axes. And the moment when the fingertip F is horizontally rotated while being in contact with the object B.

In the above equation, F _x , F _y , and F _z are the x-axis direction in the first coordinate system C1 in FIG. 2, which is the width direction of the finger, the y-axis direction of the coordinate system that is the thickness direction of the finger, and the finger direction. Represents the contact force in the z-axis direction of the same coordinate system, which is the length direction, and My represents the moment about the y-axis of the same coordinate system, which is the horizontal rotation.
Further, S1 _x , S1 _y , and S1 _z are the x-axis direction, the y-axis direction, and the z-coaxial direction in the second coordinate system C2 in the figure measured by the force measuring means 16 (S1) on the right side in FIG. Represents the pressing force of.
S2 _x , S2 _y and S2 _z are the x-axis direction, the y-axis direction and the z-axis direction in the third coordinate system C3 in the figure measured by the force measuring means 16 (S2) on the left side in FIG. Indicates pressing force.
Further, k _{1 to} k ₁₂ represent preset gains, and take positive values other than 0.

Here, in the present embodiment, the first to third coordinate systems C1 to C3 are set as shown in FIG. 2, and the pressing force and the contact force direction of each component are as follows. In all coordinate systems, the y component has a positive value in the upper part of FIG. 2, and the z component has a positive value in the front part of FIG. On the other hand, in the x component, the directions of positive values are opposite between the first and second coordinate systems C1 and C2 and the third coordinate system C3. That is, in the first and second coordinate systems C1 and C2, the right side in FIG. 2 takes a positive value, and in the third coordinate system C3, the left side in the figure takes a positive value. In other words, the pressing force in the width direction of the finger has a positive value in the direction of compressing the contact member, which is the direction in which the side surface of the finger bulges due to the contact of the finger T.

According to the above equation, the contact force F _{x in the} x-axis direction, which is the width direction of the finger, is obtained by multiplying the x and y components (S1 _x , S1 _y ) in the pressing force applied to the right contact member 15 by a predetermined gain. , The x and y components (S2 _x , S2 _y ) of the pressing force to the contact member 15 on the left side are multiplied by predetermined gains, respectively, and added to cancel each added value in units of the contact member 15. Is required by doing.

Further, the contact force F _{y in the} y-axis direction, which is the thickness direction of the finger, is added after multiplying the x and y components (S1 _x , S1 _y ) in the pressing force on the contact member 15 on the right side by predetermined gains. Then, the x and y components (S2 _x , S2 _y ) of the pressing force to the contact member 15 on the left side are multiplied by predetermined gains, respectively, and added, and the added values are summed.

Further, the contact force F _{z in the} z-axis direction, which is the length direction of the finger, is the z component S1 _z in the pressing force on the right contact member 15 and the z component S2 _z in the pressing force on the left contact member 15. It is obtained by multiplying each by a gain to a predetermined value and totaling them.

Further, the moment M _y direction of the y-axis of lateral rotation of fingers, and z components S1 _z in the pressing force to the right of the contact member 15 and to the z component S2 _z in the pressing force to the left of the contact member 15 It is obtained by multiplying each by a gain and canceling them.

In the body part contact force sensor 10 in the above-described embodiment, the sensor body 11 is attached to the fingertip to obtain the contact force of the fingertip, but the present invention is not limited to this, and the sensor body 11 is It is also possible to adopt a configuration in which the body part can be attached to other body parts such as a finger part other than the fingertip, and the contact force of the body part is obtained.

Further, in the above-described embodiment, the contact force is obtained from the pressing force applied to the contact members 15 at two locations, but the contact member 15 may be provided at one location or at three locations or more depending on the body part or the like for measuring the contact force. In the same manner as described above, the pressing force acting on each contact member 15 due to the deformation of the peripheral portion is measured by the force measuring means 16, and the contact force is calculated by using the measurement result. good.

In addition, the configuration of each part of the device in the present invention is not limited to the illustrated configuration example, and various modifications can be made as long as substantially the same action is exhibited.

10 body part contact force sensor 11 sensor body 12 processing means 15 contact member 16 force measuring means B object T finger (body part)
T1 contact part

Claims (4)

In a body part contact force sensor for measuring the contact force acting on the contact part of the body part of the measurement subject when the body part contacts a predetermined object,
A sensor main body that detects a state when a peripheral portion of the contact portion is deformed by the contact force; and a processing unit that obtains the contact force based on a detection result of the sensor main body,
The sensor body has a contact member that is disposed so as to be contactable with the peripheral portion and that is pressed as the peripheral portion is deformed, and a magnitude of the pressing force of each component acting on the contact member in the orthogonal triaxial directions. Equipped with force measuring means for measuring,
In the processing means, from the measurement result of the force measuring means, the components of the pressing forces acting on the contact member are used, and the magnitude of the contact force is calculated by each component. Body part contact force sensor. The contact member is arranged at least at two places in the peripheral portion,
2. The body part contact force sensor according to claim 1, wherein the force measuring unit measures the magnitude of the pressing force of each component acting on each of the contact members in the directions of the three orthogonal axes. The contact member is arranged so as to be contactable on the finger side surfaces on both sides in the width direction of the finger contacting the object,
In the processing means, the pressing force in the width direction of the finger and the pressing force in the thickness direction of the finger are multiplied by a predetermined gain for each contact member, and then added, and the added value is calculated for each contact member. By canceling, the contact force in the width direction is obtained, and the contact force in the thickness direction is obtained by summing up the added values calculated for each of the contact members, and the length direction of the finger is obtained. 3. The body part contact force sensor according to claim 2, wherein the contact force in the lengthwise direction is obtained by multiplying each of the pressing forces of 1. by a predetermined gain and then totalizing the product. In the processing means, the moment in the lateral rotation direction of the finger is obtained by multiplying each pressing force in the length direction by a predetermined gain and canceling each pressing force. The body part contact force sensor according to claim 3.

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