JP2004174696A - Power sensor overload protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism for preventing a power sensor from being broken by external force over a measuring range or overload, in a work operation of an anthropomorphic robot, an assembling work robot, and the like. <P>SOLUTION: When applied to the power sensor 3 used by being installed between an arm 1 and an end effector 2 in a manipulator, the mechanism comprises an active engaging member 8 having a driving portion 7 fixed to the arm 1, and a passive engaging member 8 fixed to the end effector 2. The active engaging member is driven to be engaged with the passive engaging member, thereby fixing the arm 1 and the effector 2. By releasing the engagement, the power sensor 3 is actuated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an overload prevention device for a force sensor used by being attached to a manipulator or a hand of an industrial robot.
[0002]
[Prior art]
For general-purpose industrial robots and industrial robots dedicated to various types of equipment, force sensors are installed in each part to detect and adjust the force applied to the object handled by the robot or unscheduled others. While performing a series of operations, a target operation is performed. In particular, in high-end robots such as assembly robots and humanoid robots that perform work by force control, information on the force acting on the target by the hand or manipulator corresponding to the hand and the reaction force received from the target and others is controlled. Therefore, it is desirable to incorporate and use a six-axis force sensor.
[0003]
Since the force sensor is provided between the base and the end effector that connects to the robot body, such as a shoulder and an arm, the end sensor can withstand the weight and inertia force of the end effector itself, and the action of the end effector and the object It is necessary to have a strong structure that can withstand the force and also withstand the impact force when colliding with an obstacle or the like. In the first place, the force sensor measures based on a change in a physical quantity due to an acting force, usually distortion of a member. Therefore, if the rigidity of a portion acting on the sensitive member is high, measurement with high sensitivity cannot be performed. Therefore, when measuring based on the deformation of a sturdy member, it is difficult to provide high sensitivity that is sensitive to weak forces or minute changes in force, because measurement resolution and measurement accuracy cannot be expected. is there.
[0004]
Therefore, especially when the measurement accuracy is a problem, a highly delicate sensor is used even if it is somewhat delicate, and it is naturally easy to break down and tends to suffer from maintenance and repair. Since the force sensor is expensive, and the one used by being incorporated into the robot takes a long time to replace, it is desirable to prevent breakage and failure as much as possible. On the other hand, in the working environment of a humanoid robot or an assembly robot, interference with surrounding articles is likely to occur, so that a force sensor incorporated in the robot is easily damaged. Despite these circumstances, no protection mechanism has been previously found that accurately protects a high-precision six-axis force sensor used in a robot.
[0005]
Note that as an overload protection device, there is a so-called mechanical lock that prevents a deformation of a predetermined amount or more from occurring by a mechanism that presses and fixes a convex tapered surface provided on one of an arm and a hand to a concave tapered surface provided on the other. . The mecha lock can sufficiently cope with an extremely large load far exceeding the rating of the sensor. However, due to limited manufacturing accuracy, the force sensor locks accurately near the load to be detected to protect the sensor and protects it so accurately that it does not need to be calibrated, especially when reusing the sensor. The target load cannot be set. Therefore, even if protection is performed using a mechanical lock, the sensor mechanism is not damaged, but usually the sensor calibration matrix needs to be readjusted, and in some cases, the strain gauge is damaged and overhaul is required.
[0006]
Further, as disclosed in Patent Literature 1 and Patent Literature 2, a robot is interposed between an arm and a hand to fix the robot and the hand so that the hand can be moved relative to the arm when necessary. There is a so-called tool floating device that absorbs a positional shift of a tool. For example, the floating device of the hand described in Patent Document 1 includes an intermediate moving member having a flange supported by a number of hard spheres in a housing fixed to an arm, and a spherical receiving means provided inside the intermediate moving member through a spherical receiving means. And a structure for fixing the hand to the rotating member. The intermediate moving member is movable in the x and y directions with respect to the housing and is rotatable around the axis of the hand. The pivot member pivots around the center with respect to the intermediate moving member. Further, the hand can be fixed at a predetermined position with respect to the arm by pressing the positioning ball against the tapered surface of the ball receiver provided in the housing by the air drive piston charged in the rotating member.
[0007]
The floating device described in Patent Document 1 is applied to a hand equipped with a force sensor. When measurement is performed, the connection of the floating device is released, the arm and the hand are connected via a force sensor, and when an overload is applied, the floating device is floated. It is conceivable that the apparatus is operated to fix the hand to the arm to protect the force sensor. However, in this floating device, a pneumatic drive device is installed on the hand side, so that the load on the hand increases and the sensitivity of the force sensor is impaired, and the load changes when applying and releasing the pressurized air. Difficulty in calibration. In addition, the mechanism of the floating device is complicated, which increases the cost of the device.
[0008]
The floating device described in Patent Literature 2 also incorporates an air cylinder driven by pressurized air so that the piston is in close contact with the contact surface or floats from the contact surface to be free. This floating device cannot release all six axes. In other words, only a limited number of shafts can be released even if a certain force or more acts. Therefore, it is not preferable to protect all six axes because the size of the end effector such as a hand is increased, and the force control is complicated. Further, since a complicated pneumatic device is provided on the hand side, there is the same difficulty as that described in Patent Document 1. These floating devices use a passive mechanism that releases the connection when a certain level of force is applied.However, the protection of the force sensor is based on the output of the force sensor, and the arm is actively activated at an appropriate load level. And the hand need to be combined to protect the sensor.
[0009]
In the six-axis force sensor, it is preferable that all the six axes are released from the mechanism during measurement and an acting force is applied to the sensor pressure-sensitive portion, and at this time, no other external force acts. On the other hand, when the sensor is protected, it is necessary that the hand and the arm are mechanically fixed so that no force acts on the sensor pressure sensing portion. As described above, a protection device having the technical idea of fixing the hand and the arm to protect the sensor has not existed before. In the current situation where the force sensor cannot be protected, it is necessary to select the measurement range of the sensor so that it can withstand the maximum acting force that can occur during the robot's operation cycle. Has been invited.
[0010]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 07-096487 [Patent Document 2]
JP-A-07-051954
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a mechanism for preventing a force sensor from being destroyed by an external force or an overload exceeding a measurement range in a work operation of a humanoid robot or an assembly work robot. It is.
[0012]
[Means for Solving the Problems]
The force sensor overload protection device according to the present invention is applied to a force sensor installed and used between an arm and an end effector in a manipulator, and includes an active engagement member having a drive unit fixed to the arm and an end effector. A passive engagement member fixed to the arm, the active sensor is driven to engage with the passive engagement member, thereby fixing between the arm and the effector, and the force sensor is activated by releasing the engagement. It is characterized by doing so.
[0013]
According to the force sensor overload protection device of the present invention, at the time of measurement, the arm and the end effector are disengaged from each other, and the reaction force applied to the end effector directly acts on the force sensor, so that the force measurement accuracy is improved. When the sensor is protected, the end effector is fixed to the arm, and no force from the end effector is transmitted to the force sensor, so that the sensor is completely protected even if an unexpected large force acts from the outside. Also, since the component of the force sensor overload protection device provided on the end effector side is passive, unlike a mechanism using a spring or air pressure, no extra force is generated when the engagement is released Since the measurement is not adversely affected, the measurement accuracy of the sensor can be secured.
[0014]
Further, the force sensor overload protection device of the present invention is a plurality of claw-equipped rotating rods in which an active engaging member is fixed at its tip to an eccentric disk having an outer edge whose distance from the rotation axis is different, On the other hand, the passive engaging member is a receiving member having a recess which presses and engages an outer edge portion of the disk whose distance from the rotation axis is large, and comprises a passive engaging member and an active engaging member. It may be. The eccentric disk can be easily rotated by a simple drive mechanism with small output, and the arm and end effector are securely fixed by pressing the eccentric disk claw to the deepest part of the recess. Can be combined.
[0015]
It is preferable that an even number of the claw-equipped rotating rods are provided and arranged so that the operating moments of the passive engagement members are canceled out by a pair rotating in opposite directions. When the rotating rod is rotated in the same direction, the end effector is driven to rotate in the same direction, so that there is a possibility that the end effector does not work effectively as a robot hand, but if the rotating rod is rotated in the opposite direction for each pair, , The end effector can be stopped by canceling the rotation.
[0016]
Further, it is preferable that the rotation axis of the rotary rod with claws is arranged in a direction parallel to the axis of the arm and the end effector, and the engagement recess of the receiving member is formed on a surface parallel to the axis of the arm and the end effector. By making the engaging concave surface and the rotating rod claw act perpendicularly to make the acting force perpendicular to the arm end effector axis, a neutral effect is exerted on the end effector, and the end effector is not intended It can be prevented from moving in the direction.
[0017]
Further, the engaging dent is provided inside the receiving member toward the axis of the arm and the end effector, and the rotating rod with the claw is provided inside the engaging dent and pushes the eccentric disk outward when driven. You may make it contact and fix. In addition, the engaging dent is provided toward the outside of the receiving material, and the plurality of rotary rods with claws are provided outside the engaging dent, and when driven, press the eccentric disk toward the inside and fix it. May be performed. In addition, the rotating rods with claws are provided on the inside and outside of the receiving material, and the engagement recesses are provided on both the inside and outside surfaces of the receiving material, and the inner rotating rod and the outer rotating rod are fixed so as to sandwich the receiving material. It goes without saying that it may be possible to do so.
[0018]
Further, a plurality of telescoping rods in which the active engaging member includes a core rod having a flange and a sheath rod having a contact surface, and the core rod and the sheath rod are driven in opposite directions to each other. Wherein the passive engagement member has a hole through which the core rod of the telescopic rod passes, and a receiving portion which is sandwiched between the hole by a flange and a contact surface, and when the telescopic rod is driven, the telescopic rod is passively engaged. A structure that engages with the receiving portion of the joining member to fix the space between the arm and the end effector may be employed. In the structure using the telescopic rod, a complicated structure for balancing the force is not required because the force for rotating the engagement member does not work.
[0019]
Further, the active engagement member may be a belt having an actuator that fixes one end and pushes and pulls the other end, and the passive engagement member may be a receiving portion that engages with the belt. When the belt is pulled by the actuator, the belt can be engaged with the receiving portion to fix the arm and the effector. It is preferable that the belt be disposed at a position where the belt is divided around the axis of the end effector. The belt fastening device can be manufactured with an extremely simple structure.
In the force sensor overload protection device of the present invention, the active engagement member can be driven when the overload state is detected based on the output of the force sensor to protect the force sensor. Activating based on the measured value of the force sensor enables the protective action to be taken immediately when a load suitable for preventing danger in the measurable range of the force sensor is detected, so that the force sensor is extremely safe. Not only does the sensor section not need to be damaged, and there is no need to perform calibration again when the protection state is released.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the force sensor overload protection device of the present invention will be described in detail using embodiments. The overload protection device according to the present invention is a device that protects a force sensor by fixedly connecting the arm and the hand when an excessive force is applied between the arm and the hand.
[0021]
Embodiment 1
FIG. 1 is a partial cross-sectional view illustrating a force sensor overload protection device according to a first embodiment, and FIGS. 2 to 4 are explanatory diagrams each illustrating an example of a locking mechanism.
[0022]
In the overload protection device of the present embodiment, a six-axis force sensor 3 is interposed between the arm 1 and the hand 2. The arm 1 and the force sensor 3 are fixed on the front and back of the arm mounting base 4, respectively, and the force sensor 3 and the hand 2 are fixed on the front and back of another hand mounting base 5, respectively. A disk-shaped flange 6 is provided on the outer periphery of the arm mounting base 4, and a plurality of rotary motors 7 are fixed on the flange 6 at appropriate intervals. The rotating motor 7 drives the rotating rod 8 to rotate. An eccentric disk 9 is fixed to the tip of the rotating rod 8. Further, a ring 10 having a wedge-shaped recess 11 formed inside is fixed downward on the outer peripheral portion of the hand mounting base 5. It is needless to say that an air-driven rotary actuator or the like can be used instead of the electric rotary motor as the rotary motor for rotating the rotary rod 8.
[0023]
As shown in FIG. 2, in the eccentric disk 9, the distance from the axis of the rotating rod 8 to the outer periphery differs depending on the rotation angle. The outer periphery 12 of the eccentric disk 9 which is initially separated from the inner surface of the ring 10 approaches the inner surface of the ring 10 as the rotating rod 8 rotates, and eventually hits the surface of the wedge-shaped recess 11. Further, when the rotating rod 8 rotates, the wedge-shaped recess 11 is pulled in the vertical direction, and moves to a position where the tip of the eccentric disk 9 fits into the deepest portion 13 of the recess. The plurality of rotating rods 8 operate simultaneously to adjust the positions of the wedge-shaped recesses 11 so that the tip of the eccentric disk 9 projects toward the innermost portion 13 so that the arm 1 and the hand 2 do not change their positions with respect to each other. Fixed to. Therefore, no stress acts on the force sensor 3 and the force sensor 3 is completely protected from overload. The dotted curve in FIG. 2 is the inner ridge 14 of the ring 10.
[0024]
When the rotating rod 8 is driven in the opposite direction to separate the tip of the eccentric disk 9 from the ring 10 so that the hand 2 and the arm 1 are connected via the force sensor 3, the force sensor 3 operates. Thus, six-axis force applied to the hand 2 can be measured. In the measurement state, the extra part added to the portion connected to the hand 2 is almost only the ring 10. Since the ring 10 is a relatively lightweight and passive element without a driving mechanism, it does not strongly interfere with the measurement of the reaction force.
[0025]
In the force sensor overload protection device according to the present embodiment, when the overload state is detected based on the output of the force sensor 3, the rotation motor 7 is driven to protect the force sensor 3. If the operation is performed based on the measurement value of the force sensor 3, the protection operation can be performed immediately when an appropriate load in the measurable range of the force sensor 3 is detected. Since the protection can be performed at a low force setting level, the protection is extremely safe, and there is no need to worry about damage to the sensor unit, and it is not necessary to perform the calibration operation again when the protection state is released.
[0026]
By equipping an even number of rotating rods 8 to rotate and urge one pair at a time in the opposite direction, when the eccentric disk 9 is pressed against the recess 11 inside the ring 10 and the hand 2 is fixed, 2 does not generate unnecessary rotational moment, and does not affect the force sensor 3.
[0027]
The rotating rod 8 may be arranged inside the ring 10 as shown in FIG. 2, or may be arranged outside the ring 10 as shown in FIG. When the rotating rod 8 is arranged outside the ring 10, the wedge-shaped recess is formed outside the ring 10, and the eccentric disk 9 presses the outermost portion 13 of the recess from the outside to move the hand 2 at a certain position. To be fixed. Further, as shown in FIG. 4, the rotating rods 8 may be provided as a pair on the outside and inside of the ring 10 and pressed so as to sandwich the ring 10 from both sides.
[0028]
According to the force sensor overload protection device of the present embodiment, it is possible to detect an accurate force without applying an extra force such as a spring force or a pipe tension force during normal measurement, and when protecting the force sensor. The arm and the hand can be fixed so that the acting force does not reach the force sensor. Further, the overload level to be protected can be accurately determined by using the measurement result of the force sensor, so that damage to the sensor can be reliably prevented. Further, by selecting the measurement range of the force sensor to a range suitable for a level requiring measurement, the sensitivity of the sensor can be increased, and the measurement accuracy can be greatly improved.
[0029]
Further, in the overload protection device according to the present embodiment, even if the eccentric disk or the wedge-shaped recess is worn, by adjusting the rotation angle, a completely fixed state can be guaranteed. Note that the overload protection device of the present embodiment can be used by fixing an end effector such as an arc welding torch on the distal end side and fixing the end effector to the arm. In such a method of use, severe breakage of the robot arm or the end effector can be prevented by disconnecting the end effector from the arm when an unexpected external force is generated.
[0030]
Embodiment 2
FIG. 5 is a partial sectional view illustrating a force sensor overload protection device according to a second embodiment. In this embodiment, a telescopic rod is used in place of a rotating rod as a locking component. In the overload protection device of the present embodiment, similarly to the first embodiment, a six-axis force sensor 23 is interposed between the arm 21 and the hand 22. The arm 21 and the force sensor 23 are fixed to the front and back of the arm mounting base 25, respectively, and the force sensor 23 and the hand 22 are fixed to the front and back of another hand mounting base 24, respectively. A skirt 26 having a cylindrical shape and a flange at the lower end is provided on the outer peripheral portion of the arm mounting base 25, and a plurality of telescopic rods 27 are fixed on the flange of the skirt 26 at appropriate intervals. . The telescopic rod 27 includes a core rod 28 and a sheath rod 29.
[0031]
A flange is attached to the tip of the core rod 28, and a tapered surface 30 whose diameter decreases in the axial direction is formed below the flange. Further, the sheath-side rod 29 has a tapered surface 31 extending outward at the upper end. The hand mounting base 24 and the arm mounting base 25 are provided with holes 32 through which the core-side rod 28 penetrates and holes 33 through which the sheath-side rod 29 penetrates, for each position of each telescopic rod 27. An upper edge of the through hole 32 of the hand mounting base 24 is formed with a tapered surface 34 to which the downward tapered surface 30 of the core rod 28 is joined, and an upward tapered surface of the sheath rod 29 is formed on the lower edge. A tapered surface 35 to which the junction 31 is joined is formed.
[0032]
The core rod 28 and the sheath rod 29 each include a core actuator 36 and a sheath actuator 37 that are driven in the vertical direction, and these actuators 36 and 37 are fixed on a flange 38 provided at the lower end of the skirt 26. Is done. Any linear drive device such as a fluid-driven cylinder or a rotary drive device using screws can be used as the actuator. The core rod 28 and the sheath rod 29 are driven in opposite directions. The force sensor 23 measures the force such that the tapered surfaces 30, 31 of the rods 28, 29 are separated from the tapered surfaces 34, 35 of the hand mounting base 24. Further, by driving the rods 28 and 29 in opposite directions to reduce the distance between the tapered surfaces 30 and 31 and to sandwich the hand mounting base 24, the hand 22 is fixed to the arm 21 and a large force is applied to the force sensor 23. Protect from action.
[0033]
In the force sensor overload protection device of the present embodiment, the core-side rod 28 and the sheath-side rod 29 expand and contract in opposite directions, so that no extra operating force is applied to the hand 22 and the hand 22 is driven in a direction parallel to the axis. Do not give extra operating moment. Further, only the passive elements are included on the hand side, and all the active elements such as actuators are arranged on the arm side, so that the force measurement by the force sensor 3 is performed accurately. The tapered surfaces 30, 31, 34, and 35 may be of any shape, such as a cone, a pyramid, or a sphere, as long as the corresponding surfaces are compatible. Further, even if the tapered surface is worn, the initial function can be ensured by adjusting the expansion / contraction stroke.
[0034]
Embodiment 3
FIG. 6 is a partial sectional view illustrating a force sensor overload protection device according to a third embodiment, and FIG. 7 is a perspective view thereof. In this embodiment, a band is used as a locking component. In the overload protection device of this embodiment, a six-axis force sensor 43 is interposed between the arm 41 and the hand 42. The arm 41 and the force sensor 43 are respectively fixed on the front and back of the arm mounting base 44, and the force sensor 43 and the hand 42 are fixed on the front and back of the hand mounting base 45. The hand mounting base 45 is provided with a tape winding cylinder 46 surrounding the hand 42, and an outer peripheral portion of the arm mounting base 44 is provided with a tape supporting cylinder 47 up to the height of the tape winding cylinder 46.
[0035]
A tape end support 48 and an actuator 49 are provided inside the tape support cylinder 47, and a tape 50 is passed between them. One end of the tape 50 is fixed to the tape end support 48, and the tape 50 is wound around the tape winding cylinder 46, and the other end is engaged with the actuator 49 so that the tape 50 can be wound up or loosened by the actuator 49. The tape 50 is wound around a plurality of tape-wrapped cylinders 46 to prevent imbalance in force when the arm 41 and the hand 42 are fixed to protect the force sensor 43. If a plurality of tapes 50 can be arranged at equal intervals, it is more preferable to arrange the tapes 50 at symmetric positions one by one. The actuator 49 can be configured using an electric motor, an air cylinder, or the like. The rigidity at the time of fixing can be adjusted by the force generated by the actuator 49. The tape 50 may be a steel tape, a rubber tape, or the like, or may be a string.
[0036]
【The invention's effect】
As described above, the force sensor overload protection device of the present invention does not apply extra force such as spring force, air pressure, or piping rigidity during normal force measurement, and shuts off external acting force when protecting the force sensor. As a result, safety can be ensured, so that a force sensor used for a humanoid robot or an assembly robot can be prevented from being damaged by overload or abnormal external force. In particular, if the external force is actively shut off using the measurement result of the force sensor, the measurement range of the force sensor can be limited to the required range, and the sensitivity of the sensor can be increased to achieve highly accurate measurement. Will be possible.
[Brief description of the drawings]
FIG. 1 is a partial sectional view illustrating a force sensor overload protection device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating an example of a locking mechanism used in the first embodiment.
FIG. 3 is an explanatory view showing another example of the locking mechanism used in the first embodiment.
FIG. 4 is an explanatory view showing still another example of the locking mechanism used in the first embodiment.
FIG. 5 is a partial sectional view illustrating a force sensor overload protection device according to a second embodiment of the present invention.
FIG. 6 is a partial sectional view illustrating a force sensor overload protection device according to a third embodiment of the present invention.
FIG. 7 is a perspective view illustrating a force sensor overload protection device according to a third embodiment.
[Explanation of symbols]
Reference Signs List 1 robot arm 2 robot hand 3 force sensor 4 arm mounting base 5 hand mounting base 6 disk-shaped flange 7 rotating motor 8 rotating rod 9 eccentric disk 10 ring 11 wedge-shaped recess 12 outer periphery of eccentric disk 13 Innermost part of ring 14 Arm 21
Reference Signs List 22 Hand 23 Force sensor 24 Hand mounting base 25 Arm mounting base 26 Skirt 27 Telescopic rod 28 Core rod 29 Sheath rod 30, 31, 34, 35 Tapered surface 32 Core rod through hole 33 Sheath rod through hole 36 Core side actuator 37 Sheath side actuator 38 Flange

Claims (9)

A manipulator that uses a force sensor installed between an arm and an end effector, comprising: an active engaging member having a driving unit fixed to the arm; and a passive engaging member fixed to an end effector. The force sensor is actuated by driving the actuator to engage the passive engagement member to fix the arm and the effector, and releasing the engagement to activate the force sensor. . The active engagement member is a plurality of claw-equipped rotary rods having a distal end fixed to an eccentric disk having an outer edge having a different distance from the rotation axis, and the passive engagement member is a rotary shaft of the disk. 2. The force sensor overload protection device according to claim 1, wherein the receiving member has a recess that presses and engages an outer edge portion having a large distance from a core. The plurality of claw-equipped rotating rods are provided in an even number, and are arranged such that operating moments of the passive engaging members are canceled out by a pair rotating in opposite directions. 2. The force sensor overload protection device according to 2. The rotation axes of the plurality of claw-equipped rotating rods are arranged in a direction parallel to the axis of the arm and the end effector, and the engagement recess of the receiving member is formed on a surface parallel to the axis of the arm and the end effector. The force sensor overload protection device according to claim 2 or 3, wherein: The engaging recess is provided inside the receiving member toward the axis of the arm and the end effector, and the plurality of rotary rods with claws are provided inside the engaging recess and when driven, the eccentric shape is formed. 5. The overload protection device according to claim 4, wherein the disk is fixed by pressing the disk outward. The engaging recess is provided toward the outside of the receiving member, and the plurality of rotary rods with claws are provided outside the engaging recess and, when driven, push the eccentric disk inward. The force sensor overload protection device according to claim 4, wherein the device is fixed by applying. The active engaging member is a plurality of telescopic rods that are driven in opposite directions with a core side rod having a flange and a sheath side rod having a contact surface, and the passive engaging member is a telescopic rod of the telescopic rod. A receiving portion that has a hole through which the core-side rod passes and is sandwiched between the flange and the contact surface around the hole, and when the telescopic rod is driven, the telescopic rod engages with the receiving portion and the arm and the end; The force sensor overload protection device according to claim 1, wherein a space between the effectors is fixed. The active engagement member is a belt having an actuator that fixes one end and pushes and pulls the other end, and the passive engagement member is a receiving portion that engages with the belt, and the belt is pulled by the actuator. The force sensor overload protection device according to claim 1, wherein the belt and the belt engage with the receiving portion to fix the space between the arm and the end effector. . 8. The device according to claim 1, wherein when the overload state is detected based on an output of the force sensor, the active engagement member is driven to engage the passive engagement member. 9. Force sensor overload protection device.

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