Force detection device and robot

Abstract

To provide a force detection device that can accurately measure a force.SOLUTION: A force detection device in an example of the present disclosure comprises: a movable part; a first magnet that is displaced with the movable part; a second magnet that, when the first magnet is displaced, urges the first magnet in a direction to prevent the displacement; and a sensor that detects the displacement of the movable part or the first magnet.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a force detection device and a robot. [Background technology]

[0002] One force detection device that uses a worm gear composed of a worm wheel and a worm is a technology in which the torque of the worm wheel is received by the axial force of the worm biased by a leaf spring, and the torque is detected by detecting the displacement of the worm (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-070257 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional configuration, mechanical contact between the worm and the leaf spring generates friction loss, which may reduce the accuracy of torque measurement.

[0005] An object of the present disclosure is to provide a force detection device and a robot that are capable of measuring force with high accuracy. [Means for solving the problem]

[0006] A force detection device in one embodiment of the present disclosure includes a movable part, a first magnet that displaces together with the movable part, a second magnet that urges the first magnet in a direction that suppresses displacement when the first magnet is displaced, and a sensor that detects displacement of the movable part or the first magnet.

[0007] A robot in one embodiment of the present disclosure includes a force detection device including a movable part, a first magnet that displaces together with the movable part, a second magnet that urges the first magnet in a direction that suppresses the displacement of the first magnet when the first magnet is displaced, and a sensor that detects the displacement of the movable part or the first magnet. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a force detection device and a robot that are capable of measuring force with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration example of a force detection device; [Diagram 2] A diagram showing an example of a worm supported by an integrated case. [Diagram 3] A diagram showing an example using multiple leaf springs with different spring constants. [Figure 4] FIG. 1 is a diagram showing an example of a force detection device equipped with a displacement sensor that detects the displacement of a case. [Diagram 5] Diagram showing an eddy current displacement sensor [Figure 6] Diagram showing a photosensor [Figure 7A] Diagram showing a capacitive displacement sensor [Figure 7B] Diagram showing a capacitive displacement sensor [Figure 8] Diagram showing a laser displacement sensor [Figure 9] Diagram showing the relationship between displacement and repulsive force [Figure 10] FIG. 1 shows an example of a force detection device having an arm attached thereto. [Figure 11] FIG. 1 shows an example of a force detection device using one second magnet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are merely examples, and the present disclosure is not limited to the following embodiments.

[0011] However, in some cases, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations of substantially the same configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0012] First, the principle of detecting torque, which is a force acting in the rotational direction, from displacement will be described.

[0013] 1 is a diagram showing an example of the configuration of a force detection device 100. The force detection device 100 is composed of a worm 110, a worm wheel 120, and an elastic body 130. When the worm 110 is rotated around its axis, the helical teeth 111 of the worm 110 come into contact with the gear of the worm wheel 120, causing the worm wheel 120 to rotate around the axis 121 of the worm wheel. The worm 110 is supported by a bearing portion 112.

[0014] On the other hand, when torque is generated in the worm wheel 120 of the force detection device 100, the worm 110 is displaced in the thrust direction. If the worm 110 is biased by the elastic body 130 in a direction that suppresses the displacement of the worm 110, the worm 110 is displaced in the thrust direction until the amount of displacement reaches a point where the torque of the worm wheel 120 and the repulsive force of the elastic body 130 generated by the displacement of the worm 110 are balanced.

[0015] If the torque of the worm wheel 120 is T, the radius of the worm wheel 120 is r, the elastic constant of the elastic body 130 is k, the force in the thrust direction of the worm 110 generated by T (hereinafter referred to as the "worm thrust force") is f, and the thrust displacement is x, then: T = r × f (1) f = k × x (2) Therefore, the relationship between torque T and thrust displacement x is T = r × k × x (3) It becomes.

[0016] In other words, if r and k are known, the torque T can be detected from the thrust displacement x.

[0017] On the other hand, if we transform equation (1) f = T / r (4) Equation (4) describes the relationship between the torque T of the worm wheel 120 and the worm thrust force f.

[0018] Here, it is taken into consideration that friction exists in the bearing portion 112 of the worm 110.

[0019] When the worm 110 is held by sliding bearings at n locations, if the friction coefficients of each bearing are μ0, μ1, . . . μn and the normal forces of each sliding bearing are F0, F1, . . . Fn, the total friction force is μ0×F0+μ1×F1+. . . +μn×Fn, so the worm thrust force f is f=T / r-μ0×F0-μ1×F1-...-μn×Fn...(5) It becomes.

[0020] In the conventional example shown in FIG. 1, the worm 110 is supported by bearing portions 112 at two locations, so there are sliding bearings at least at two locations.

[0021] If T / r is smaller than the maximum friction force and is balanced with the friction force, the worm thrust force f will be 0 and no thrust displacement x will occur, so the torque T cannot be detected.

[0022] Also, if T / r is larger than the frictional force, the frictional force will cause an error when calculating the torque T from the thrust displacement x, and the accuracy of force detection will deteriorate.

[0023] 2 is a diagram showing an example in which the worm 110 is supported by an integrated case 230. By supporting the entire case 230 by a linear slider 250 in rolling contact, the worm 110 is held by extremely small rolling friction, making it possible to detect torque with high accuracy.

[0024] Fig. 3 is a diagram showing an example using a plurality of leaf springs with different spring constants. An example using leaf springs 310 and 311 as the elastic body 130 in Fig. 1 is shown. Leaf spring 310 with a small spring constant is brought into contact with case 230 in advance, and leaf spring 311 with a large spring constant is brought into contact when case 230 is displaced by a predetermined amount, thereby enabling highly accurate detection of small forces.

[0025] In such a configuration, friction loss occurs due to mechanical contact between the case 230 and the leaf springs 310 and 311, which may reduce the accuracy of torque measurement. Therefore, there is a demand for a method of detecting torque with even higher accuracy.

[0026] Furthermore, due to limitations in the processing and assembly precision of the device, the precision with which the force is detected at the time when leaf spring 311 contacts case 230 may decrease.

[0027] Furthermore, since the elastic modulus of the leaf springs 310 and 311 is a fixed value, the leaf springs must be replaced in order to change the force measurement range.

[0028] As shown in FIG. 3, the spring constant can be changed by bringing leaf spring 311 into contact with case 230, and thereby the force measurement range can be changed. However, each time the measurement range is changed, it is necessary to add a new leaf spring, and there is a limit to the number of times that the range can be changed.

[0029] Furthermore, when a robot arm is attached to the worm wheel 120, the weight of the arm causes the worm wheel 120 to rotate, which poses a problem of reduced accuracy in detecting the torque acting on the arm.

[0030] In the following, a force detection device that solves the above problems and a robot equipped with the force detection device will be described in detail. Note that, although the force detection device will be described below for a case in which the final force detection target is torque, which is a force acting in the rotational direction, the final force detection target may also be worm thrust force.

[0031] <Embodiment 1> 4 is a diagram showing an example of a force detection device 400 equipped with a displacement sensor that detects the displacement of the case 230. The force detection device 100 is mounted on, for example, a robot.

[0032] The force detection device 400 includes a movable part 110, a worm wheel 120, a case 230, a magnet 431, and a sensor 440. The movable part 110, the case 230, and the magnet 431 together form a support device 432.

[0033] The movable part 110 is, for example, a worm that constitutes a worm gear together with a worm wheel 120. The worm gear has a structure in which, by rotating the movable part 110, the helical teeth 111 of the worm 110 come into contact with the gear of the worm wheel 120, causing the worm wheel 120 to rotate about an axis 121.

[0034] The worm wheel 120 is a worm wheel that constitutes a worm gear together with the movable part 110, which is a worm. The worm wheel 120 rotates due to the rotation of the movable part 110. When a torque due to an external force is applied to the worm wheel 120 and the worm wheel 120 rotates, the worm wheel 120 displaces the movable part 110 in the thrust direction.

[0035] The case 230, together with the movable part 110 and the magnet 431, constitutes a support device 432. The case 230 houses the movable part 110 therein, and has a hole for allowing the movable part 110 and the worm wheel 120 inside to come into contact with each other.

[0036] It should be noted that case 230 is not limited to being box-shaped, but may be of any shape as long as it supports movable part 110, displaces together with movable part 110, and is supported by rolling contact with another member (e.g., linear slider 250).

[0037] Movable part 110 is fixed to case 230 in the thrust direction. That is, movable part 110, case 230, and magnet 431, which constitute support device 432, move together in the thrust direction.

[0038] Sensor 440 detects the displacement of movable part 110, case 230, or magnet 431. Then, the magnitude of torque is detected from the displacement detected by sensor 440. Sensor 440 is desirably a non-contact type displacement sensor.

[0039] As a non-contact type displacement sensor, an eddy current type displacement sensor shown in Fig. 5 can be used. In an eddy current type displacement sensor, a high frequency magnetic field is generated by passing a high frequency current through a coil inside a sensor head 510, and when a metal 520 is present in this magnetic field, an eddy current is generated on the surface of the metal 520 due to electromagnetic induction according to the distance between the metal 520 and the sensor head 510, and the oscillation amplitude changes.

[0040] The eddy current displacement sensor is a sensor that measures the distance between the sensor head 510 and the metal 520 by utilizing the fact that the magnitude of the oscillation amplitude correlates with the distance between the sensor head 510 and the metal 520. When the movable part 110 has a portion made of the metal 520, the displacement of the movable part 110 can be detected by detecting how much the oscillation amplitude has changed.

[0041] As another example of a non-contact type displacement sensor, a photosensor shown in Fig. 6 can be used. The photosensor is a sensor in which a light emitting section made up of a light emitting element 610 that emits light faces a light receiving section made up of a light receiving element 620 that receives light and outputs a signal, and when an object 630 passes between the light emitting element 610 and the light receiving element 620, part of the light emitted by the light emitting element 610 is blocked, so that the amount of light received by the light receiving element 620 changes.

[0042] The movable part 110 is disposed as the target object 630, and the displacement of the movable part 110 can be detected by detecting how much the amount of light received by the light receiving element 620 has changed.

[0043] As yet another example of a non-contact type displacement sensor, a capacitance displacement sensor shown in Fig. 7A or 7B can be used. The capacitance displacement sensor shown in Fig. 7A is a sensor that utilizes a change in capacitance caused by a change in the distance between a movable electrode 720 and a fixed electrode 730 that constitute a capacitor due to the displacement of an object 710.

[0044] Alternatively, as shown in FIG. 7B, a movable electrode 720, which displaces integrally with the object 710, moves in and out between fixed electrodes 730 arranged opposite to it, changing the opposing area between the movable electrode 720 and the fixed electrode 730, thereby changing the capacitance.

[0045] In this embodiment, the target object 710 is the movable part 110. By disposing a fixed electrode 730 across a space from the metallic movable part 110, the displacement of the movable part 110 can be detected from a change in the electrostatic capacitance of a capacitor formed by the fixed electrode 730 and the movable part 110.

[0046] As yet another example of a non-contact type displacement sensor, a laser displacement sensor shown in Fig. 8 can be used. The laser displacement sensor is a sensor that detects position information of an object by emitting laser light from a light-emitting element 810 to an object 820 and detecting the light receiving position on a light-receiving element 830 or the time until the light is received.

[0047] By using the movable part 110 as the target object 820, the displacement of the movable part 110 can be detected from the light receiving position or the time until the light is received.

[0048] It should be noted that by using a non-contact displacement sensor as described above, the displacement sensor does not affect the displacement of the movable part 110. Furthermore, a force can be detected by a displacement sensor that is less expensive than a torque sensor.

[0049] The photosensor or laser displacement sensor can be used for the movable part 110 made of materials other than metal. Also, as the non-contact displacement sensor, sensors other than those exemplified in Figs.

[0050] The magnet 431 is integrated with the support device 432. When a force is applied to the movable part 110 and the movable part 110 is displaced, the magnet 431 biases the movable part 110 in a direction that suppresses the displacement due to a repulsive force between the magnets 451 and 452. The magnet 431 biases at least one of the movable part 110 and the case 230.

[0051] For example, the magnet 431 is a permanent magnet, and the magnets 451 and 452 are electromagnets. The magnet 431 may be an electromagnet, or may be a magnet that is a combination of a permanent magnet and an electromagnet. The magnets 451 and 452 may be permanent magnets, or may be a magnet that is a combination of a permanent magnet and an electromagnet. The magnets 431, 451, and 452 may be electromagnets, permanent magnets, or magnets that are a combination of a permanent magnet and an electromagnet, as long as they can generate magnetic force.

[0052] The repulsive force between magnet 431 and magnets 451 and 452 will be described.

[0053] When no torque is generated in the worm wheel 120, that is, in the initial state, the distance between the magnet 431 and the magnet 451, and the distance between the magnet 431 and the magnet 452 are both L. The S pole of the magnet 431 has -q m1 There is a magnetic charge of q on the north pole. m1 There is a magnetic charge of -q on the south pole of magnet 451. m2 There is a magnetic charge of q on the north pole. m2 There is a magnetic charge of -q at the south pole of magnet 452. m3 There is a magnetic charge of q on the north pole. m3 There is a magnetic charge of

[0054] When torque is generated in the worm wheel 120 and the magnet 431 is displaced by a distance x toward the magnet 452, the repulsive force F1 due to the south pole of the magnet 431 and the south pole of the magnet 451 is expressed as follows:

number

number

[0055] The total repulsive force F acting on magnet 431 is calculated as F = F1 - F2. In addition, the permanent magnet and electromagnet are each considered to be rods with a south pole and a north pole at both ends, and the length is sufficiently long compared to the diameter so that the existence of the opposite magnetic pole can be ignored.

[0056] Magnetic charge q of magnet 431 m1 is the surface magnetic flux density at the end B1 [T (tesla)], and the cross-sectional area of ​​the end S p [m 2 ], the cross-sectional area of ​​the end S p If we set the value of q to be negligibly small for the entire system, m1 =B1S p [Wb (Weber)].

[0057] On the other hand, the magnetic charge q of electromagnet 451 m2 can be calculated as follows. The coil radius is a [m] and the length is L E [m], the number of turns per unit length is n [ / m], and the magnetic permeability of the core is μ c [H / m], and the coil current is I2 [A]. The diameters of the coil and core are the same, i.e., the thickness of the coil winding is ignored.

[0058] In this case, the magnetic flux density B2 [T] at the center of the coil end is

number

[0059] Cross-sectional area of ​​the end S E [m 2 ] and is negligibly small for the entire system, then the magnetic charge q m2 teeth,

number

[0060] If the left and right electromagnets are of the same configuration, the repulsive force F1 is

number

[0061] Similarly, the repulsive force F2 is

number

[0062] In the end, the repulsive force F of magnet 431 is

number

[0063] For example, if magnet 431 has an average surface magnetic flux density of 500 [mT] at the end and an area of ​​the end of 28.26 [mm 2 In this case, the magnetic charge q of magnet 431 is m1 q m1 =B1S p =500×10 -3 x28.26x10 -6 =1.4×10 -5 [Wb].

[0064] On the other hand, both magnets 451 and 452 have a coil radius of 3 mm, a length of 30 mm, a number of turns per unit length of 2000 [ / m], and a core permeability of 6.3 × 10 -3 [H / m] and the coil current is 100 [mA].

[0065] In this case, the magnetic charge q of magnet 451m2 teeth,

number

[0066] Here, the magnetic permeability of air is μ = 1.25663753 × 10 -6 [H / m]. If the initial distance L is 1 mm, the total repulsive force F is

number

[0067] Fig. 9 is a diagram showing the relationship between the displacement x and the repulsive force F. It can be seen from Fig. 9 that a small force applied causes a large displacement, but a large force applied does not cause a large displacement. In other words, by detecting force based on the repulsive force of the magnet, it is possible to detect small forces precisely, while also detecting large forces.

[0068] <Embodiment 2> In the first embodiment, it is possible to control the magnetic force by controlling the current flowing through the electromagnet. That is, by increasing the current flowing through the electromagnet, the magnetic force increases, and the repulsive force due to the magnetic force increases. The increase in repulsive force means that a stronger force is detected for the same displacement. Also, by decreasing the current flowing through the electromagnet, the magnetic force decreases, and the repulsive force due to the magnetic force decreases. The decrease in repulsive force means that a weaker force is detected for the same displacement.

[0069] Therefore, a control device (not shown) can change the range of forces to be measured by changing the current flowing through the electromagnet according to the range of forces to be measured. The control device can increase the current flowing through the electromagnet when measuring a wide range of forces, and decrease the current flowing through the electromagnet when measuring a narrow range of forces.

[0070] The control device can also differentiate the current flowing through the electromagnet of magnet 151 from the current flowing through the electromagnet of magnet 152. By the control device differentiating the current flowing through the electromagnet of magnet 151 from the current flowing through the electromagnet of magnet 152, the force detection device can differentiate the range of forces measured when movable part 110 is displaced toward magnet 151 from the range of forces measured when movable part 110 is displaced toward magnet 152.

[0071] Furthermore, when both the first magnet 431 and the second magnets 451 and 452 are permanent magnets and at least one of the first magnet 431 and the second magnets 451 and 452 is an electromagnet, the control device may control the current of the electromagnet so that the first magnet 431 does not come into contact with the second magnets 451 and 452. This makes it possible to prevent a change in the magnetic quantity of the permanent magnet due to contact between the first magnet 431 and the second magnets 451 and 452.

[0072] In addition, when at least one of the first magnet 431 and the second magnets 451 and 452 has a permanent magnet and an electromagnet, the control device can also calibrate the individual differences in the magnetic force of the permanent magnet by controlling the current of the electromagnet.

[0073] <Embodiment 3> In the first or second embodiment, when a structure such as an arm is attached to the worm wheel, torque is generated by the arm's own weight depending on the angle of the arm.

[0074] FIG. 10 is a diagram showing an example of a force detection device 1000 having an arm 1060 attached thereto.

[0075] When the arm 1060 is tilted, the weight of the arm 1060 acts on the worm wheel 120 as torque T, and a worm thrust force is applied to the movable part 110. The arm 1060 is connected to the worm wheel 120, and the worm wheel 120 is connected to the movable part 110. That is, the arm 1060 is connected to the movable part 110.

[0076] A control device (not shown) calculates torque T due to the weight of arm 1060 from the inclination of arm 1060. The control device can calculate a magnetic force that compensates for the inclination of arm 1060 from the worm thrust force due to torque T and the displacement of movable part 110 due to the worm thrust force. Furthermore, the control device can calculate a current to be passed through magnets 451 and 452 that is necessary to generate a magnetic force that compensates for the inclination of arm 1060. The currents passed through magnets 451 and 452 may be different.

[0077] The control device may increase the current flowing through the electromagnet of the second magnet 452 that is in the direction of the force applied to the movable part 110 or the first magnet 431 due to the weight of the arm 1060, and decrease the current flowing through the electromagnet that constitutes the second magnet on the opposite side to the direction of the force.

[0078] For example, in FIG. 10, the weight of arm 1060 causes a worm thrust force to act on movable part 110 to the right, so the control device increases the current flowing through the electromagnet that constitutes magnet 452 and decreases the current flowing through the electromagnet that constitutes magnet 451.

[0079] The control device passes a current of the calculated magnitude through magnets 451 and 452, thereby generating a repulsive force against magnet 431, compensating for the displacement of movable part 110 and returning movable part 110 to a position where no torque T due to the weight of arm 1060 is applied.

[0080] For example, the control device can control the current using a table that indicates a correspondence between the angle of the arm 1060 calculated in advance and the current flowing through the electromagnet. For example, the angle of the arm 1060 can be detected by the angle of the joint of the robot. The angle of the arm 1060 may be detected by a camera or a sensor.

[0081] <Fourth embodiment> In each of the above-described embodiments, when the same current is applied to the electromagnets of magnets 451 and 452 which are the second magnet, the second magnet can be configured as a single magnet.

[0082] 11 is a diagram showing an example of a force detection device using one second magnet 1151. For example, by making each pole of magnet 1151 configured in a substantially U-shape correspond to each pole of magnet 431, the second magnet can be configured with one magnet.

[0083] <Modification> In each of the above-described embodiments, the repulsive force of the magnet is used to suppress the displacement of the movable part 110, but the attractive force of the magnet may be used to suppress the displacement of the movable part 110. That is, the attractive force acting between the first magnet 431 and the second magnets 451, 452, 1151 may suppress the displacement of the first magnet 431, and as a result, the displacement of the movable part 110 may be suppressed.

[0084] <Effects> By using a magnet instead of a leaf spring, it is possible to measure force without mechanical contact. When a magnet is used, the relationship between displacement and force changes nonlinearly, making it possible to measure a wide range of forces, from weak to strong. Furthermore, when an electromagnet is used, the measurement range can be changed by changing the current flowing through the electromagnet. Furthermore, the current flowing through the electromagnet can compensate for the weight of the structure itself.

[0085] Although the embodiments have been described above with reference to the drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the claims. It is understood that such modified or altered examples also belong to the technical scope of the present disclosure. In addition, the components in the embodiments may be arbitrarily combined within the scope of the present disclosure.

[0086] (1) A force detection device in one embodiment of the present disclosure includes a movable part, a first magnet that displaces together with the movable part, a second magnet that urges the first magnet in a direction suppressing displacement of the first magnet when the first magnet is displaced, and a sensor that detects displacement of the movable part or the first magnet.

[0087] (2) In one embodiment of the force detection device according to the present disclosure, in the force detection device of (1), the first magnet and the second magnet are permanent magnets, electromagnets, or magnets that combine the permanent magnet and the electromagnet.

[0088] (3) According to an embodiment of the present disclosure, there is provided a force detection device according to (1), wherein the first magnet is provided on a support device that supports the movable part.

[0089] (4) In one embodiment of the force detection device disclosed herein, in the force detection device of (1), the first magnet is biased by a repulsive force between the first magnet and the second magnet.

[0090] (5) In one embodiment of the force detection device of the present disclosure, in the force detection device of (1), at least one of the first magnet and the second magnet comprises an electromagnet or a magnet that combines the electromagnet with a permanent magnet, and the force detection device further comprises a control unit that changes the magnetic force of the electromagnet by controlling current when the measurement range of force detection is changed.

[0091] (6) In one embodiment of the force detection device disclosed herein, in the force detection device of (5), the control unit increases the current when the measurement range is widened and decreases the current when the measurement range is narrowed.

[0092] (7) In one embodiment of the force detection device of the present disclosure, in the force detection device of (1), at least one of the first magnet and the second magnet comprises an electromagnet or a magnet that combines the electromagnet with a permanent magnet, and further comprises a control unit that cancels the force applied to the movable part or the first magnet due to the weight of the movable part or the weight of a structure provided on or connected to the movable part by controlling the current flowing through the electromagnet.

[0093] (8) In one embodiment of the force detection device disclosed herein, in the force detection device of (7), the second magnet has two electromagnets on either side of the first magnet corresponding to the north and south poles of the first magnet, and the control unit makes the current flowing through the electromagnets in the direction of the force applied to the movable part or the first magnet, as viewed from the first magnet, greater than the current flowing through the electromagnets in the opposite direction to the force direction.

[0094] (9) One embodiment of the force detection device according to the present disclosure is the force detection device of (1), in which at least one of the first magnet and the second magnet comprises an electromagnet or a magnet that combines the electromagnet with a permanent magnet, and further comprises a control device that controls the current flowing through the electromagnet so that the first magnet and the second magnet do not come into contact with each other.

[0095] (10) One embodiment of the force detection device according to the present disclosure is the force detection device of (1), wherein at least one of the first magnet and the second magnet comprises a permanent magnet and an electromagnet, and further comprises a control unit that calibrates individual differences in the magnetic force of the permanent magnet by controlling a current in the electromagnet.

[0096] (11) A robot according to one embodiment of the present disclosure includes a force detection device as described in (1). [Industrial Applicability]

[0097] One embodiment of the present disclosure is useful in a force sensing device. [Explanation of symbols]

[0098] 100 Force detection device 110 Moving parts 111 Spiral teeth 112 Bearing section 120 Worm Wheel 121 Axis 130 Elastic Body 230 cases 250 Linear Slider 310, 311 Leaf springs 431, 451, 452, 1151 Magnets 432 Support device 440 Sensors 510 Sensor Head 520 metal 610, 810 Light emitting element 620, 830 Photodetector 630, 710, 820 Object 720 Movable Electrode 730 Fixed electrode 1060 Arm

Claims

1. A movable part; A first magnet that is displaced together with the movable portion; a second magnet that biases the first magnet in a direction that suppresses the displacement of the first magnet when the first magnet is displaced; a sensor for detecting a displacement of the movable portion or the first magnet; A force detection device comprising:

2. The first magnet and the second magnet include a permanent magnet, an electromagnet, or a magnet that is a combination of the permanent magnet and the electromagnet. The force detection device according to claim 1 .

3. The first magnet is provided on a support device that supports the movable part. The force detection device according to claim 1 .

4. The first magnet is biased by a repulsive force between the first magnet and the second magnet. The force detection device according to claim 1 .

5. At least one of the first magnet and the second magnet comprises an electromagnet or a magnet that is a combination of the electromagnet and a permanent magnet, A control unit is further provided that changes the magnetic force of the electromagnet by controlling a current when a measurement range of the force detection is changed. The force detection device according to claim 1 .

6. The control unit increases the current when the measurement range is to be expanded, and decreases the current when the measurement range is to be narrowed. The force detection device according to claim 5 .

7. At least one of the first magnet and the second magnet comprises an electromagnet or a magnet that is a combination of the electromagnet and a permanent magnet, A control unit is further provided that cancels a force applied to the movable part or the first magnet due to the weight of the movable part or the weight of a structure provided on or connected to the movable part by controlling a current flowing through the electromagnet. The force detection device according to claim 1 .

8. The second magnet has two electromagnets on both sides of the first magnet, the electromagnets corresponding to the north and south poles of the first magnet, The control unit makes a current flowing through an electromagnet located in a direction of a force applied to the movable part or the first magnet when viewed from the first magnet larger than a current flowing through an electromagnet located on an opposite side to the direction of the force. The force detection device according to claim 7.

9. At least one of the first magnet and the second magnet comprises an electromagnet or a magnet that is a combination of the electromagnet and a permanent magnet, a control device for controlling a current flowing through the electromagnet so that the first magnet and the second magnet do not come into contact with each other; The force detection device according to claim 1 .

10. At least one of the first magnet and the second magnet comprises a permanent magnet and an electromagnet, A control unit is further provided which calibrates individual differences in magnetic force of the permanent magnet by controlling a current of the electromagnet. The force detection device according to claim 1 .

11. A robot comprising the force detection device according to claim 1.

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