Robot hand and robot system

Abstract

To provide a robot hand and a robot system in which such a problem that appropriate grasping of the state concerning action to an object is difficult in the conventional robot hand is resolved.SOLUTION: A robot hand 2 is used together with a force sensor 5 which detects such a force as to change along with an action to an object 900. The robot hand 2 includes a hand part 10 having a contact part 27 brought into contact with the object 900 and a transmission part 7 which is connected with the force sensor 5 and the contact part 27, and transmits a force applied to the contact part 27 so that the force detected by the force sensor 5 is changed in accordance with the change of a force applied to the contact part 27. The transmission part 7, in such a case that the position of the contact part 27 with respect to the force sensor 5 exists within a predetermined range, is constituted so as to change the force to be transmitted to the force sensor 5 along with a displacement of the contact part 27 into a non-linear form. By the use of the robot hand 2, whether a position of the contact part 27 with respect to the force sensor 5 exists within the predetermined range can be easily detected.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a robot hand that acts on a target object, and a robot system.

Background Art

[0002] Conventionally, robot systems for performing various actions on target objects have been used in manufacturing sites and the like. As such a robot system, there is one having a robot hand for making contact with a target object, gripping various tools used for the target object, and the like. In a robot system having a robot hand, a force sensor for detecting a force applied to the robot hand may be used. For example, the position, movement, and the like of the robot hand can be controlled according to the detection result of the force sensor.

[0003] For example, Patent Document 1 below describes a method for detecting jamming of a fitting component using a force sensor, with respect to jamming that occurs during a fitting operation using a robot.

[0004] Further, Patent Document 2 below describes an assembly apparatus that assembles a component gripped by a hand onto a workpiece, wherein an obstacle is detected by a force sensor so as to change the search trajectory of the assembly hole of the component.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when using a robot hand to perform tasks such as gripping and fitting by controlling it while understanding the state of the force acting on an object using force sensors as described above, there is a problem in that the difficulty of control can increase. In other words, the forces detected by force sensors generally include forces that are difficult to estimate and change depending on the situation, such as friction. When forces from factors other than the force to be detected are also detected by force sensors, it can be difficult to properly understand the state of the force acting on the object. Therefore, it can be difficult to properly perform control based on the detection results of force sensors.

[0007] This invention was made to solve the above problems and aims to provide a robot hand and robot system that can easily grasp the state of action on an object. [Means for solving the problem]

[0008] The robot hand of the first invention is a robot hand used in conjunction with a force sensor that detects a force that changes in accordance with an action on an object, and comprises a hand portion having a contact portion that contacts the object, and a transmission portion connected to the force sensor and the contact portion, which transmits the force applied to the contact portion such that the force detected by the force sensor changes in accordance with the change in the force applied to the contact portion, wherein the contact portion is displaceable in a predetermined direction relative to the force sensor, and the transmission portion has a transmission force changing means configured to change the force transmitted to the force sensor nonlinearly in accordance with the displacement of the contact portion when the position of the contact portion relative to the force sensor is within a predetermined range, the robot hand.

[0009] This configuration makes it easy to detect whether the position of the contact point relative to the force sensor is within a predetermined range, and allows for an appropriate understanding of the state of the action on the object.

[0010] Furthermore, the robot hand of this second invention is configured such that, compared to the first invention, the transmission force changing means generates a click sensation when the position of the contact part relative to the force sensor is within a predetermined range, and transmits the click sensation to the force sensor.

[0011] This configuration makes it easier to detect whether the position of the contact portion relative to the force sensor is within a predetermined range.

[0012] Furthermore, the robot hand of this third invention, compared to the first or second invention, has a transmission unit comprising a first structure connected to a force sensor and a second structure displaceable relative to the first structure together with a contact portion, the first and second structures being connected to a transmission force changing means, the transmission force changing means comprising a plurality of teeth and an engaging portion that engages with at least one of the plurality of teeth, and is configured such that the engagement state between the plurality of teeth and the engaging portion changes in accordance with the change in the position of the second structure relative to the first structure.

[0013] With this configuration, it is possible to easily detect whether the position of the contact portion relative to the force sensor is within a predetermined range.

[0014] Furthermore, the robot hand of this fourth invention is a robot hand that, with respect to any one of the first to third inventions, has an action part configured such that the contact part comes into contact with the object and moves closer to the object as it is displaced in a predetermined direction relative to the force sensor. This configuration allows for an appropriate understanding of the state of the action on the object and enables control of the action of the working part on the object.

[0015] Furthermore, the dual-arm robot system of this fifth invention is a dual-arm robot system that, in addition to any one of the first to fourth inventions, is equipped with at least two robot hands, the hand portions of each robot hand are arranged to face each other in the first direction, and is configured to be able to simultaneously bring each hand portion close to an object and act upon it.

[0016] With such a configuration, in a dual-arm robot system, it is possible to appropriately grasp the state related to the action on the target object. Advantageous Effects of Invention

[0017] According to the robot hand of the present invention, it is possible to appropriately grasp the state related to the action on the target object. Brief Description of Drawings

[0018] [Figure 1] Perspective view showing the robot system according to the present embodiment [Figure 2] Side view showing the structure of the same hand unit and transmission unit [Figure 3] Diagram showing an example of the configuration and operation of the same transmission force changing means [Figure 4] Graph showing an example of the relationship between the force in the first direction detected by the same force sensor and the displacement amount of the contact portion in the first direction [Figure 5] Diagram showing a configuration example of a transmission unit according to a modification of the present embodiment [Figure 6] Graph showing an example of the relationship between the force in the first direction detected by the force sensor and the displacement amount of the contact portion in the first direction in the present modification Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the robot hand and a robot system using the same will be described with reference to the drawings.

[0020] The coordinates shown in the following drawings are common among the respective drawings. Regarding the robot system, the z-direction of the coordinates is a direction perpendicular to the horizontal plane. The x-direction is a direction perpendicular to the z-direction, and the y-direction is a direction perpendicular to the z-direction and perpendicular to the x-direction. The z-direction may be referred to as the up-down direction (the direction that is positive on the z-axis as viewed from the origin of the illustrated coordinates is up), the x-direction may be referred to as the left-right direction (the direction that is positive on the x-axis as viewed from the origin of the illustrated coordinates is left), and the y-direction may be referred to as the front-rear direction (the direction that is positive on the y-axis as viewed from the origin of the illustrated coordinates is rear).

[0021] Further, regarding the robot hand, the Z-direction of the coordinates is a direction perpendicular to the horizontal plane. The X-direction is a direction perpendicular to the Z-direction, and the Y-direction is a direction perpendicular to the Z-direction and perpendicular to the X-direction. The Z-direction may be referred to as the up-down direction (the direction that is positive on the Z-axis as viewed from the origin of the illustrated coordinates is up), the Y-direction may be referred to as the left-right direction (the direction that is positive on the Y-axis as viewed from the origin of the illustrated coordinates is right), and the X-direction may be referred to as the front-rear direction (the direction that is positive on the X-axis as viewed from the origin of the illustrated coordinates is front).

[0022] In the following description, the shapes and positional relationships of the respective parts may be described by indicating the respective directions in this way, but the explicit indication of directions is merely for the convenience of description, and does not limit the orientation, posture, or the like of each device according to the present invention during use.

[0023] (Embodiment)

[0024] Figure 1 is a perspective view showing a robot system 1 according to the present embodiment.

[0025] The robot system 1 includes two robot hands 2 (a first robot hand 2b, a second robot hand 2c), a first moving unit 110, a second moving unit 120, a third moving unit 130, and a carriage 140.

[0026] Figure 1 shows the robot system 1 in a state where the robot hand 2 is gripping an object 900. The robot hand 2 used in this embodiment is used in particular to grip an object to be transported (hereinafter referred to as the object 900).

[0027] The object 900 is not particularly limited, but may be something used in a manufacturing site, such as a plasma power supply or a welding jig. The weight of the object 900 is not particularly limited, but may be a weight that is difficult for a human to transport, for example, 30 kg or more, or 50 kg or more. Also, the weight of the object 900 may be such that it does not require the use of a large transport vehicle such as a forklift, for example, 200 kg or less, 150 kg or less, or 100 kg or less. The robot system 1 can grasp an object 900, for example, one which has plate-like portions having a predetermined thickness at both ends in one direction.

[0028] Figure 1 shows an example where a flat object 900 is being gripped, but the object 900 may be a three-dimensional object, or it may be a plate-shaped member on which another device or the like is placed. In the latter case, for example, the plate-shaped member and the device or other object placed on that plate-shaped member may constitute the object 900. Note that the object 900 may not have a flat plate-shaped portion.

[0029] In this embodiment, the two robot hands 2 are positioned spaced apart in the first direction in the horizontal plane. Hereinafter, the x-direction will be considered the first direction. The two robot hands 2 are positioned so as to be separated from each other in the left-right direction. The first robot hand 2b is positioned on the right side, and the second robot hand 2c is positioned on the left side.

[0030] The first robot hand 2b and the second robot hand 2c each include an arm 4 that supports the hand portion 10, a transmission unit 7, the hand portion 10, and a force sensor 5 provided between the arm 4 and the transmission unit 7. In other words, in this embodiment, the robot system 1 has two arm portions 4 that are spaced apart from each other to the left and right. The hand portion 10 is indirectly attached to each arm portion 4 via the force sensor 5 and the transmission unit 7. The hand portions 10 of the two robot hands 2 are positioned to face each other in the first direction.

[0031] In this embodiment, each hand portion 10 is configured to simultaneously hold the object 900. That is, the robot system 1 is configured to bring both hand portions 10 close to the object 900 at the same time and act on the object 900. By holding the object 900 with the two hand portions 10, the magnitude of the moment acting on the hand portions 10 during object transport can be reduced. Therefore, the requirements for strength, rigidity, and other properties of each component of the robot system 1 can be reduced, making it easier to achieve, for example, miniaturization and weight reduction of the robot system 1.

[0032] The force sensor 5 can detect the force applied to the hand unit 10. The force sensor 5 detects the force that changes as the hand unit 10 acts on the object 900. In this embodiment, the force applied to the hand unit 10 is transmitted to the force sensor 5 via the transmission unit 7. The force sensor 5 is used, for example, to obtain the weight of the object 900 held by the hand unit 10. Each force sensor 5 is, for example, a sensor for detecting external forces. The sensor for detecting external forces may be, for example, a 3-axis or 6-axis force sensor. When each force sensor 5 is a sensor for detecting external forces, it is preferable that the sensor is arranged so as to be able to measure the weight of the object 900 held by each hand unit 10.

[0033] The transmission unit 7 is positioned between the hand unit 10 and the force sensor 5. The transmission unit 7 is configured to transmit the force applied to the hand unit 10 to the force sensor 5. It can also be said that the force sensor 5 detects the force transmitted by the transmission unit 7. The transmission unit 7 may be configured to transmit only a portion of the force detected by the force sensor 5. In other words, the force sensor 5 may be configured to detect both the force transmitted by the transmission unit 7 and the force transmitted by other parts. The configuration of the hand unit 10 may also be considered as including the transmission unit 7. In other words, the configuration of the hand unit 10 may be specified as including the transmission unit 7.

[0034] In this embodiment, the force applied to the hand portion 10 in the first direction can be transmitted to the force sensor 5 as a characteristic force via the transmission portion 7. Details of this will be described later.

[0035] It can be said that each arm portion 4 has a hand attachment portion (not shown) on the surface facing the other arm portion 4 to which a hand portion 10 or the like is attached. The force sensor 5 can be said to be a sensor for detecting the force applied to the hand attachment portion.

[0036] The mounting position of the force sensor 5 is not limited to the position between the arm portion 4 and the hand portion 10. The force sensor 5 may be positioned, for example, between the arm portion 4 and the structure supporting the first robot hand 2b or the second robot hand 2c. Alternatively, the arm portion 4 may be composed of multiple members, and the force sensor 5 may be positioned between any of these members. Furthermore, the force sensor 5 may be a sensor (for example, a strain gauge) attached to a member constituting the arm portion 4, etc., that can detect the strain of the member.

[0037] Furthermore, although the transmission unit 7 is mounted between the force sensor 5 and the hand unit 10, other members or structures may be placed between the force sensor 5 and the transmission unit 7, or between the transmission unit 7 and the hand unit 10.

[0038] In this embodiment, the weight applied to the hand portion 10 can be obtained by the force sensor 5 in both the first robot hand 2b and the second robot hand 2c. The sum of the weights obtained by each force sensor 5 may be, for example, the weight of the object 900, or the weight of the object 900 plus the weights of both hand portions 10 and the transmission portion 7.

[0039] Each robot hand 2 is movable relative to the trolley 140 by the moving parts 110, 120, and 130. Each hand part 10 is movable in a first and second direction in the horizontal plane, and is movable in the vertical direction, i.e., the z direction. The second direction is perpendicular to the first direction, i.e., the y direction. Each hand part 10 is moved in the directions of the three axes in the Cartesian coordinate system. Alternatively, the configuration of the robot hand 2 may be considered as one of the moving parts 110, 120, or 130 being included in the robot hand 2.

[0040] The first moving unit 110 supports each robot hand 2. That is, the first moving unit 110 supports each hand unit 10. The first moving unit 110 displaces each hand unit 10 in a first direction. The first moving unit 110 can move each hand unit 10 independently in the first direction. That is, the first moving unit 110 is configured to displace the arm unit 4 and change the distance between the two hand units 10. The robot system 1 is configured so that by moving each hand unit 10 with the first moving unit 110, it can, for example, hold or release an object 900 held by each hand unit 10. The robot system 1 can also move the object 900 held by each hand unit 10 in the first direction by moving each hand unit 10 simultaneously in the same direction with the first moving unit 110.

[0041] The first moving section 110 includes, for example, a first support section 111 that supports each hand section 10, and a linear actuator that moves each hand section 10 in a first direction relative to the first support section 111. More specifically, for example, a guide along the first direction is provided on the bottom surface of the first support section 111 that extends in the first direction, and a slider is assembled to the guide so as to be slidable in the first direction. Each arm section 4 to which each hand section 10 is attached is fixed to a different slider.

[0042] The second moving part 120 supports the first moving part 110 and moves the first moving part 110 in the second direction. Therefore, each hand part 10 is moved together in the second direction by the second moving part 120. The second moving part 120 includes, for example, a second support part 121 that supports the first support part 111 of the first moving part 110, and a linear actuator that moves the first support part 111 in the second direction relative to the second support part 121. More specifically, for example, a guide along the second direction may be provided on the bottom surface of the second support part 121 that extends in the second direction, and a slider may be mounted on the guide so as to be slidable in the second direction. The upper surface of the first support part 111 may be fixed to the slider.

[0043] The third moving section 130 supports the second moving section 120 and moves the second moving section 120 vertically. Therefore, each hand section 10 is moved vertically together by the third moving section 130. The third moving section 130, as an example, includes a pair of support columns 131 and 132 spaced apart in the first direction, a top plate 133 connecting the upper ends of the support columns 131 and 132, a lifting section 134 whose end is supported by the pair of support columns 131 and 132 and which supports the second support section 121 of the second moving section 120, and a pair of linear actuators that move the lifting section 134 vertically synchronously with respect to the pair of support columns 131 and 132. More specifically, guides along the vertical direction may be provided on the lifting section 134 side of the vertically extending support columns 131 and 132, and sliders may be assembled to these guides so as to be slidable vertically. Furthermore, both ends of the lifting section 134 in the first direction may be fixed to the slider.

[0044] In the moving sections 110, 120, and 130, for example, a slider may be assembled to two or more parallel guides. Furthermore, the linear actuators of the moving sections 110, 120, and 130 may each independently comprise, for example, a rack-and-pinion mechanism and a driving means for rotating the pinion; a ball screw mechanism and a driving means for rotating the screw shaft of the ball screw mechanism; a pair of pulleys, an endless belt stretched between the pair of pulleys, and a driving means for rotating the pulleys; or sprockets and chains may be used instead of the pulleys and belt; or other configurations are also possible. To move each hand section 10 independently in the first direction, the first moving section 110 may have a linear actuator for moving the first robot hand 2b and a linear actuator for moving the second robot hand 2c. Note that mechanisms for moving a supported object in a linear direction using guides, sliders, linear actuators, etc., are already known, and a detailed explanation is omitted. In Figure 1, the guides, sliders, and linear actuators are not shown.

[0045] The third movable part 130 is fixed to the trolley 140. The base end, i.e., the lower end, of the third movable part 130 may also be fixed to the trolley 140. For example, the trolley 140 may have a base 141 to which the base end of the third movable part 130 is fixed, and a plurality of running means 142 fixed to the base 141 and capable of traveling on a running surface such as a floor. For example, the base 141 may be a plate-shaped member. The running means 142 are usually wheels, but may also be rollers, tracks, ball casters, etc. Furthermore, the trolley 140 may or may not have a driving means for driving the running means 142. In the latter case, the trolley 140 may be moved manually. Furthermore, the manually moved trolley 140 may have fixing means to secure the running means 142 so that the trolley 140 does not move when the moving parts 110, 120, and 130 perform localized transport of the object 900. The fixing means may be, for example, wheel stoppers. In this embodiment, the case in which the trolley 140 does not have a driving means and is moved manually will be mainly described. While the object 900 is transported locally by the moving parts 110, 120, and 130, the object 900 is transported more globally by the trolley 140.

[0046] The robot system 1 includes a reception unit (not shown) for receiving operations and instructions from the user, and a control unit (not shown) for controlling the movements of the mobile units 110, 120, and 130. The reception unit may, for example, receive operations and instructions related to the mobile units 110, 120, and 130, or it may receive operations and instructions related to the trolley 140. Reception may, for example, be the reception of information input from an input device (e.g., a keyboard, mouse, touch panel, etc.), or the reception of information transmitted via a wired or wireless communication line. The reception unit may or may not include a device for performing reception (e.g., an input device, a communication device, etc.). Furthermore, the reception unit may be implemented by hardware, or by software such as a driver that drives a predetermined device.

[0047] The control unit controls the first moving unit 110, the second moving unit 120, and the third moving unit 130, respectively. Through this control, for example, the object 900 is held by each of the hand units 10, or released. This control also enables localized transport, such as positioning of the object 900. Furthermore, if the trolley 140 has a driving mechanism, the control unit may also control the movement of the trolley 140. These controls may be performed, for example, in response to operations or instructions received by the reception unit. The movement control of the trolley 140 may be, for example, movement control relating to the direction and speed of movement in response to operations received by the reception unit, or it may be autonomous movement control from a predetermined starting point to a destination.

[0048] Next, an example of the structure of the hand unit 10 and the transmission unit 7 will be described in more detail. Note that the directions shown in the description of the structure of the hand unit 10 and the transmission unit 7 do not necessarily coincide with the directions shown in the description of the configuration of the robot system 1 above, and are independent of each other.

[0049] In this embodiment, expressions such as "a part is displaced in a direction that moves it closer to or away from another part," for example, "the contact part 25 is displaced in a direction that moves it closer to the force sensor 5," represent relative displacement. That is, even in cases where the position of the contact part 25 relative to the force sensor 5 changes due to the displacement of the force sensor 5 together with the arm part 4, etc., relative to the contact part 25 which is in the same position when viewed from the outside, this is also included in the events represented by the above expression.

[0050] Figure 2 is a side view showing the structure of the hand unit 10 and the transmission unit 7.

[0051] In this embodiment, the hand portion 10 includes a base 11, an action portion 21, and a contact portion 25.

[0052] In this embodiment, the base 11 is configured to be a plate-like shape parallel to the horizontal plane. The upper surface of the base 11 becomes the contact surface that the object 900 may come into contact with when gripping the object 900. The contact surface is a substantially flat plane. In this embodiment, the contact surface is parallel to the X and Y directions. The X direction is the direction in which the hand portion 10 extends from the arm portion 4, and is sometimes referred to here as the first direction. The Y direction is perpendicular to the X direction, and is sometimes referred to here as the second direction. It can also be said that the contact surface has a shape that extends in the X direction.

[0053] The base 11 is attached to each arm portion 4 via a force sensor 5, a transmission portion 7, and a contact portion 25. In other words, the base 11 is configured to be held by the arm portions 4. Various methods can be used to attach the base 11 to the members on the arm portion 4 side. The base 11 may also be held by the arm portions 4 and force sensors 5, etc., without using the contact portion 25.

[0054] In this embodiment, a contact portion 25 is positioned on the rear end side of the base 11, above the contact surface. The contact portion 25 is positioned on the base 11 so as to be displaceable in a first direction. That is, the contact portion 25 is displaceable in a first direction, which is a predetermined direction, relative to the force sensor 5.

[0055] When the hand portion 10 performs an action such as gripping the object 900, the contact portion 25 becomes one of the parts that come into contact with the object 900. In this embodiment, the contact portion 25 can come into contact with the object 900 in the first direction.

[0056] The working portion 21 is positioned, for example, above the base 11. The working portion 21 is located above the base 11 and has an working portion 21b that is positioned opposite the contact surface of the base 11.

[0057] In this embodiment, the working portion 21 is configured using a link structure 23 having a plurality of link members that can rotate relative to each other via a plurality of axes. As shown in the figure by solid lines and dashed lines, the link structure 23 is configured to displace the working portion 21b in accordance with, for example, the displacement of the contact portion 25 in the first direction. As the contact portion 25 is displaced backward, the vertical distance between the working portion 21b and the base 11 is reduced.

[0058] With the working part 21 configured in this way, the hand part 10 can grip the object 900. In other words, in this embodiment, the working part 21 is configured such that the contact part 25 contacts the object 900 which is in front, and as the object 900 is displaced backward relative to the force sensor 5 together with the contact part 25, the working part 21b moves closer to the object 900. The object 900 is gripped by being sandwiched between the working part 21b and the contact surface of the base 11.

[0059] Furthermore, the object 900 can be grasped and transported by the robot system 1 by having its left and right ends near the respective hand portions 10 of the two robot hands 2.

[0060] Furthermore, the operating part 21 can be configured in a way different from the configuration described above. The operating part 21 may be configured to operate in response to the displacement of the contact part 25 in the first direction, for example, by using a different link structure than described above, or by using various power transmission mechanisms such as gears, rack and pinion, or pulleys. Moreover, the operating part 21 is not limited to operating in response to the displacement of the contact part 25 in the first direction. For example, it may be configured to operate in response to the displacement of the contact part 25 in a different direction than described above (for example, a second direction or vertical direction), the displacement of the base 11, or changes in force applied to the hand part 10.

[0061] Furthermore, the hand portion 10 may be equipped with an actuator, and the actuator may be configured to operate the action portion 21. The operation of the actuator may be performed in response to the detection result of the displacement of the contact portion 25 in the first direction, or it may be performed due to other events.

[0062] In this embodiment, the transmission unit 7 comprises a first structure 71, a second structure 72, and a transmission force changing means 75. The transmission unit 7 has a structure in which the first structure 71 and the second structure 72 are aligned in a first direction via the transmission force changing means 75.

[0063] The first structure 71 is connected to the force sensor 5, but it does not matter whether it is directly or indirectly connected. In other words, the first structure 71 can be said to be a structure located between the force transmission means 75 and the force sensor 5. In this embodiment, the first structure 71 has a rod-shaped member arranged to allow force input to the force sensor 5, but it is not limited to this.

[0064] The second structure 72 is connected to the hand portion 10. The second structure 72 is connected to the contact portion 25, but it does not matter whether it is directly or indirectly connected. In other words, the second structure 72 can be said to be a structure located between the force transmission means 75 and the contact portion 25.

[0065] The second structure 72 is displaceable together with the contact portion 25 relative to the first structure 71. That is, the second structure 72 is displaceable in the first direction in conjunction with the displacement of the contact portion 25 in the first direction.

[0066] In other words, in this embodiment, the transmission unit 7 is connected to the force sensor 5 and the contact unit 25. The transmission unit 7 is configured to transmit the force applied to the contact unit 25 to the force sensor 5 in such a way that the force detected by the force sensor 5 changes in response to the change in force applied to the contact unit 25.

[0067] Here, when the force applied to the contact portion 25 in the transmission unit 7 is transmitted to the force sensor 5, the force is configured to change nonlinearly by the transmission force changing means 75. The transmission force changing means 75 is configured to change the force transmitted to the force sensor 5 nonlinearly in accordance with the displacement of the contact portion 25. The transmission force changing means 75 is configured to change the force nonlinearly when the position of the contact portion 25 relative to the force sensor 5 (hereinafter sometimes simply referred to as the position of the contact portion 25) is within a predetermined range. The predetermined range may be a range with a width, or it may be a range with no width (close to zero). In other words, the predetermined range may be a range from one position to another, or it may be a position that can be called a certain point.

[0068] A nonlinear change refers to a change that does not change linearly in response to the displacement of the contact portion 25. For example, consider a case where, in a region where the position of the contact portion 25 is not within a predetermined range, the magnitude of the force in the first direction detected by the force sensor 5 increases linearly as the contact portion 25 approaches the force sensor 5. In this case, when the position of the contact portion 25 is within a predetermined range, a change such as a sudden decrease in the force in the first direction detected by the force sensor 5, or a decrease in the magnitude of the force in the first direction detected by the force sensor 5 as the contact portion 25 approaches the force sensor 5, can be described as a nonlinear change.

[0069] In this embodiment, the force transmission means 75 is configured to generate a click sensation and transmit the click sensation to the force sensor 5 when the position of the contact portion 25 is within a predetermined range. A click sensation refers to a sudden decrease in the transmitted force. Generating a click sensation can be rephrased as rapidly decreasing the force transmitted to the force sensor 5. Transmitting a click sensation to the force sensor 5 means transmitting force in such a way that the magnitude of the force detected by the force sensor 5 decreases rapidly.

[0070] Figure 3 shows an example of the configuration and operation of the transmission force changing means 75.

[0071] In this embodiment, the force transmission means 75 has, for example, a plurality of teeth 76 and an engaging portion 77 that can engage with at least one of the plurality of teeth 76. The force transmission means 75 also has a spring 78 positioned between the first structure 71 and the second structure 72. The spring 78 makes it possible to change the distance between the first structure 71 and the second structure 72 in the first direction and transmits force in the first direction between the first structure 71 and the second structure 72.

[0072] The force transmission means 75 has a structure similar to a known, so-called knock cam mechanism, which is used, for example, in a retractable ballpoint pen to extend or retract the refill with the pen tip by knocking. The configuration of the force transmission means 75 shown in Figure 3 is partially simplified, but in reality, it may include various necessary components, similar to a known knock cam mechanism. The operation of the force transmission means 75 is as follows, for example: For example, an engaging portion 77, which displaces in accordance with the displacement of the second structure 72, engages with a rotating cam composed of multiple teeth 76 (step S1). When the second structure 72 displaces toward the first structure 71, the second structure 72 presses against the rotating cam and compresses the spring 78, increasing the force applied to the first structure 71 at the other end of the spring 78. At this time, in response to the engagement between the teeth 76 and the engaging portion 77, the rotating cam rotates in a predetermined direction (a predetermined direction around an axis along the first direction) (step S2). 。 So doFurthermore, as the second structure 72 is displaced toward the first structure 71, the rotating cam rotates further in a predetermined direction, and the engagement state between the tooth 76 and the engaging portion 77 changes to a different state. Due to the repulsive force of the spring 78, the rotating cam is displaced toward the first structure 71, so the amount of compression of the spring 78 decreases sharply, and the force applied to the first structure 71 decreases sharply. That is, a click sensation occurs (step S3). After that, as the second structure 72 is displaced toward the first structure 71, the force applied to the first structure 71 increases linearly in proportion to the amount of displacement until the distance between the first structure 71 and the second structure 72 is closest. When the force applied to the second structure 72 toward the first structure 71 is released, the second structure 72 becomes able to be displaced toward the opposite side. When the engagement between the rotating cam and the engaging portion 77 is released, the rotating cam rotates in a predetermined direction, and the next tooth 76 becomes able to engage with the engaging portion 77 (return to step S1).

[0073] Figure 4 is a graph showing an example of the relationship between the force in the first direction detected by the force sensor 5 and the displacement of the contact portion 25 in the first direction.

[0074] As described above, the force transmission means 75 is configured such that, in this embodiment, as shown in the figure, the magnitude of the force in the first direction detected by the force sensor 5 changes with the displacement of the contact portion 25 in the first direction. In this embodiment, it can also be said that the magnitude of the force in the first direction detected by the force sensor 5 changes with the displacement of the second structure 72 in the first direction. That is, as described above, in the knock cam mechanism, as the rotation of the rotating cam increases, the magnitude of the force increases substantially linearly as the amount of displacement of the contact portion 25 increases until the engagement state between the engagement portion 77 and the teeth 76 changes to a different state. The point at which the amount of displacement reaches T1 is when the contact portion 25 is within a predetermined range. That is, when the amount of displacement reaches T1, the engagement state between the engagement portion 77 and the teeth 76 changes to a different state, and the amount of compression of the spring 78 decreases sharply. Accordingly, the magnitude of the detected force decreases sharply. This phenomenon can be felt as a click sensation. That is, when the amount of displacement reaches T1, a click sensation occurs, and this click sensation is transmitted to the force sensor 5.

[0075] Subsequently, as the displacement of the contact portion 25 increases further, the magnitude of the force increases again in a roughly linear fashion. This relationship between the amount of displacement and the magnitude of the detected force continues until the second structure 72 can approach the first structure 71.

[0076] Note that the change in force magnitude shown in the figure is a schematic representation, and in reality, it may differ due to differences in the spring characteristics of spring 78 (such as differences in the magnitude of its progressiveness) and other influences.

[0077] Thus, in this embodiment, the force detected by the force sensor 5 changes in accordance with the change in the force applied to the contact portion 25. When the position of the contact portion 25 relative to the force sensor 5 is within a predetermined range, the force detected by the force sensor 5 changes nonlinearly. Therefore, when performing control operations while detecting the force applied to the hand portion 10 with the force sensor 5, the force sensor 5 can obtain information for determining whether the position of the contact portion 25 relative to the force sensor 5 is within a predetermined range, which was not possible with conventional force sensors 5. Because it is easy to detect whether the position of the contact portion 25 relative to the force sensor 5 is within a predetermined range, the state of the action on the object 900 can be appropriately grasped.

[0078] Furthermore, the configuration of the means for changing the transmission force is not limited to the one using the knock cam mechanism described above. For example, it may be as follows.

[0079] Figure 5 shows an example of the configuration of the transmission unit 307 according to one modified example of this embodiment.

[0080] As shown in the figure, the transmission unit 307 has a first structure 371, a second structure 372, and a transmission force changing means 375. The transmission force changing means 375 has a plurality of teeth 376 arranged in a first direction and an engaging portion 377 that can engage with any of the teeth 376. The teeth 376 are, for example, integrally formed with the first structure 371. The engaging portion 377 is formed with the second structure 372.

[0081] In this modified example, the first structure 371 has a cylindrical portion into which the tip of the second structure 372 fits. Multiple teeth 376 are formed on the inner circumferential surface of the cylindrical portion, aligned in the first direction and having irregularities in a direction perpendicular to the first direction. The multiple teeth 376 can also be said to be the portion that forms an irregular surface opposite to the engaging portion 377.

[0082] The engaging portion 377 has a projection 377b that protrudes in a direction perpendicular to the first direction and contacts (engages) with one of the teeth 376. The projection 377b is biased toward the teeth 376, for example, by a spring.

[0083] Furthermore, a spring 78 is positioned between the first structure 371 and the second structure 372. The role of the spring 78 is the same as in the embodiment described above.

[0084] Figure 6 is a graph showing an example of the relationship between the force in the first direction detected by the force sensor 5 and the displacement of the contact portion 25 in the first direction in this modified example.

[0085] With the force transmission means 375 configured in this way, at the position of the contact portion 25 where the engaging portion 377 engages with any of the multiple teeth 376, the force detected by the force sensor 5 changes nonlinearly in accordance with the change in the first direction of the contact portion 25. That is, in the range where the engagement between the engaging portion 377 and the innermost tooth 376 is released (the range up to displacement amount T2 in the graph), the detected force repeatedly becomes stronger and weaker as the engagement state between the engaging portion 377 and the tooth 376 switches in accordance with the displacement of the contact portion 25. By detecting such changes in force, the amount of displacement of the contact portion 25 can be used as information that can be used to estimate, and the same effects as in the above-described embodiment can be obtained.

[0086] The force transmission means may have further different configurations. For example, the engaging portion, which is shaped like a leaf spring, may be able to engage with a plurality of teeth formed in the first direction or with projections formed at predetermined positions in the first direction, and when the engagement state between the engaging portion and the projections changes according to the positional relationship between the first structure and the second structure, this affects the force detected by the force sensor 5. Various mechanisms that can produce a nonlinear change in force due to a change in the positional relationship between the first structure and the second structure, such as known mechanisms for producing a tactile sensation or a click sensation, can be used as the force transmission means.

[0087] (others)

[0088] The present invention is not limited to the embodiments described above, and various modifications are possible, which are also included within the scope of the present invention.

[0089] The components of the above-described embodiments and modifications may be replaced or combined with other elements as appropriate. Furthermore, some components or functions of the above-described embodiments and modifications may be omitted.

[0090] The robot system is not limited to the transport device described above. The robot system only needs to have one or more robot hands. For example, by using the robot hand according to the above embodiment as the manipulator of the robot system, useful information for understanding the state of action on an object can be obtained by force sensors. The robot system does not need to have a cart. For example, the robot system may be fixed to a fixed base or the like.

[0091] A robot hand is not limited to one that grasps an object. A robot hand only needs to have a contact part that makes contact with an object in order to act upon it. For example, in applications where it is necessary to press an object such as a button, a robot hand can be configured to press the object using its contact part. Similarly, in applications where it is necessary to pull an object, a robot hand can be configured to pull the object using a contact part that can engage with the object. [Industrial applicability]

[0092] As described above, the robot hand according to the present invention has the effect of making it easier to appropriately grasp the state of the action on the object, and is useful as a robot hand, etc. [Explanation of symbols]

[0093] 1 Robot system, 2 Robot hand, 4 Arm section, 5 Force sensor, 7, 307 Transmission section, 10 Hand section, 11 Base, 21 Working section, 25 Contact section, 71, 371 First structure, 72, 372 Second structure, 75, 375 Transmission force changing means, 76, 376 Teeth, 77, 377 Engaging section, 900 Object

Claims

1. A robot hand used in conjunction with a force sensor that detects the force that changes in response to an action on an object, A hand portion having a contact portion that contacts the object, The device comprises a force sensor and a transmission unit connected to the contact portion, which transmits the force applied to the contact portion such that the force detected by the force sensor changes in accordance with the change in the force applied to the contact portion. The contact portion is displaceable in a predetermined direction relative to the force sensor. The transmission unit has a transmission force changing means configured such that as the amount of displacement of the contact portion relative to the force sensor in the predetermined direction increases, the magnitude of the force detected by the force sensor in the predetermined direction increases, and when the amount of displacement increases further, the magnitude of the force in the predetermined direction decreases.

2. The robot hand according to claim 1, wherein the force transmission means is configured to generate a click sensation by rapidly reducing the magnitude of the force in the predetermined direction and to transmit the click sensation to the force sensor.

3. The transmission unit has a first structure connected to the force sensor and a second structure that is displaceable relative to the first structure together with the contact unit. The first structure and the second structure are connected to the transmission force changing means, The force transmission means comprises a plurality of teeth, an engaging portion that engages with at least one of the plurality of teeth, and a spring disposed between the first structure and the second structure, wherein as the second structure is displaced toward the first structure in the predetermined direction, the position of the engaging portion with respect to the plurality of teeth in the predetermined direction changes, thereby changing the engagement state between the plurality of teeth and the engaging portion to a different state, and as the amount of compression of the spring decreases in accordance with the change in engagement state, the force transmitted to the force sensor in the predetermined direction decreases, as described in claim 1.

4. The robot hand according to claim 1, wherein the hand portion has an action portion configured to approach the object as the contact portion contacts the object and is displaced in a predetermined direction relative to the force sensor.

5. The robot comprises at least two robot hands according to any one of claims 1 to 4, The hand portions of each of the aforementioned robot hands are arranged to face each other in the first direction. A dual-arm robot system configured to simultaneously bring each of its hands close to the object and act upon it.

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