JP2018158392A - Assist suit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assist suit capable of preventing wrong action at non-wearing time.SOLUTION: An assist suit includes a driving device A capable of assisting action of an operator, a control part 49 for performing control of drive of the driving device A, and a detection sensor B capable of detecting wearing to the operator, and is constituted so that the control part 49 allows the drive of the driving device A when the wearing to the operator is detected by the detection sensor B, and on the other hand, prohibits the drive of the driving device A when the wearing to the operator is not detected by the detection sensor B.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an assist suit capable of assisting an operator's operation.

  For example, Patent Document 1 describes a conventional assist suit. The assist suit described in Patent Document 1 includes a drive device (a “leg operation unit” in the same document) capable of assisting an operator's movement, and a control unit (a “control unit” in the same document) that performs drive control of the drive device. ) And are provided. The control unit drives the drive device based on the operation of the switch.

Japanese Patent Laid-Open No. 2006-129918

  However, in the above-described conventional assist suit, for example, even when the operator is not wearing, the drive device is driven when the switch is pressed. In this way, when the drive device is driven when not worn, for example, the placed assist suit may fall over and be damaged, or an operator may perform an unexpected operation while wearing it. was there.

  In view of the above circumstances, it has been desired to provide an assist suit that can prevent malfunction when not worn.

The assist suit of the present invention is
A driving device capable of assisting the operation of the worker;
A control unit that performs drive control of the drive device;
A detection sensor capable of detecting attachment to an operator,
The control unit allows the drive device to be driven when the detection sensor detects that the worker is wearing, and when the detection sensor detects that the worker is not worn, It is configured to prohibit driving.

According to the present invention, the drive device can be driven only when the detection sensor detects the attachment to the worker, and the operation of the worker can be assisted by the drive device, and the detection sensor detects the attachment to the worker. If not, the driving device is not driven. Therefore, if it is this invention, the malfunctioning at the time of non-wearing can be prevented. For this reason, due to the malfunction of the drive device when not worn, there is a problem that the assist suit placed falls down and is damaged, or the operator performs an unexpected operation during wearing. You can avoid that.
in this way,

In the present invention,
As the detection sensor, it is preferable that a back sensor capable of detecting a pressing force by a worker's back when worn is provided.

  According to this configuration, the driving device is allowed to be driven only in a state where the back of the worker is detected by the back sensor. For example, the driving device is erroneously driven while the worker is wearing it. Can be avoided.

In the present invention,
There is a back pad that comes into contact with the back of the operator when worn,
It is preferable that the back sensor is disposed on the back side of the back pad opposite to the operator's back.

  According to this configuration, since the back sensor is hidden behind the back pad, it is possible to reduce the possibility that erroneous detection of wearing is erroneously performed by the back sensor. Further, since the back sensor is brought into a detection state by pressing the operator's back against the back pad, the driving device can be allowed to be driven in a state where the operator is firmly attached to the operator's back.

In the present invention,
A shoulder belt is provided around the operator's shoulder,
It is preferable that a tension sensor capable of detecting the tension of the shoulder belt is provided as the detection sensor.

  According to this configuration, the driving device is allowed to be driven only when the operator puts on the shoulder belt and the tension sensor is in the detection state. It is possible to avoid erroneous driving.

In the present invention,
As the detection sensor, it is preferable that a waist sensor capable of detecting the pressing force by the operator's waist when worn is provided.

  According to this configuration, the drive device is allowed to be driven only when the operator wraps the waist belt and the waist sensor is in the detection state. It is possible to avoid erroneous driving.

In the present invention,
A waist pad that comes into contact with the operator's waist when worn is provided,
The waist sensor is preferably arranged on the back side of the waist pad opposite to the operator's waist.

  According to this configuration, since the waist sensor is hidden behind the waist pad, it is possible to reduce the possibility of erroneous attachment detection by the waist sensor. In addition, since the waist sensor is brought into a detection state by pressing the operator's waist against the waist pad, the drive device is allowed to be driven in a state in which the waist sensor is firmly attached to the operator.

In the present invention,
A waist belt that can be wound around and attached to the waist of an operator by engaging a pair of belts with each other is provided.
It is preferable that an engagement sensor capable of detecting the engagement of the belt portion is provided as the detection sensor.

  According to this configuration, the driving device is allowed to be driven only when the operator winds the waist belt and engages the belt portion and the engagement sensor is in the detection state. It is possible to avoid the drive device being erroneously driven during the mounting.

It is a side view which shows the assist suit of the state with which the operator wore. It is a rear view which shows the assist suit of the state with which the operator wore. It is a perspective view which shows an assist suit. It is a block diagram which shows the control structure of an assist suit.

  Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings. In the following explanation, the notation regarding directions such as “up”, “down”, “front”, “back”, “left”, “right” is based on the viewpoint of the worker wearing the assist suit. It is said.

[Basic structure of assist suit]
The assist suit shown in FIGS. 1 to 3 and the like is attached to the body of an operator, and can apply an assist force that assists the operator in raising and lowering an object (load).

  As shown in FIG. 1 to FIG. 3, the assist suit is attached to the worker's back (back) side and supported by the operator's body, and the driving device capable of assisting the operator's operation. A, a control device 4 that controls the drive device A, a battery 5 that can supply power to the electrical system related to the drive device A, and the like.

  As shown in FIG. 1 to FIG. 3, as the driving device A, the arm assist device 2 that assists the muscle height of the arm by assisting the change operation of the load height position, which is an example of the object, the bending of the leg A waist assist device 3 is provided for assisting the stretching operation and supporting the muscle strength of the waist and legs.

  As shown in FIGS. 1-3, the main-body part 1 has assembled several members in frame shape. In other words, the main body 1 includes a pair of left and right vertical frames 6, a vertical plate-like support frame 7 that connects the left and right vertical frames 6, and the like. An arm assist device 2, a waist assist device 3, a control device 4, and a battery 5 are supported on the main body 1.

  As shown in FIGS. 1 and 3, etc., the front side of the support frame 7 is provided with left and right shoulder belts 8 wound around the shoulders of the operator and a waist belt 9 wound around the operator's waist. Yes. The waist belt 9 can be attached by being wound around the operator's waist by engaging a pair of belt portions 33 with each other. The tip portions of the pair of belt portions 33 can be switched between an engaged state and a disengaged state by a detachable buckle portion 34.

  As shown in FIGS. 1 and 3, the assist suit is provided with a back pad 29 that comes into contact with the back of the operator when worn. A pair of back pads 29 are provided on the front side of the lower portion of the support frame 7. The back pad 29 is made of a flexible material.

  As shown in FIG. 1, FIG. 3, etc., the assist suit is provided with a waist pad 32 that comes into contact with the waist of the operator when worn. The waist pad 32 is provided on the lower front side of the support frame 7. The waist pad 32 is made of a flexible material.

  The operator attaches the main body 1 to the body by hanging the waist belt 9 around the waist through the arm portions corresponding to the left and right shoulder belts 8 and hanging them around the shoulder. Thereby, as shown in FIG. 1, FIG. 2, the operator can mount | wear with an assist suit in the form which bears the main-body part 1 on the back part side.

[About the arm assist device]
As shown in FIG. 1, FIG. 2, etc., the arm assist device 2 can suspend a load and assist the lifting operation of the load. The arm assist device 2 is a winch type device capable of hanging a load. The arm assist device 2 includes left and right arm portions 10 for determining a suspension fulcrum of the load, two left and right suspension ropes 11 for hanging the load, left and right hand portions 12 for holding the load, A reel mechanism 13 that feeds and winds the suspended rope 11, a lift motor 14 that rotationally drives the reel mechanism 13, a speed change mechanism 15 that shifts the power of the lift motor 14 and transmits the power to the reel mechanism 13, and a reel An electromagnetic brake 16 or the like that can apply a braking force to the mechanism 13 is provided.

  As shown in FIG. 1, FIG. 2, etc., the left and right arm portions 10 extend from the upper ends of the left and right vertical frames 6 in the main body portion 1 toward the front upper side. As shown in FIG. 1, the left and right arm portions 10 extend through the side of the wearer's head to a location positioned in front of the worker's head. As shown in FIG. 2, the left and right arm portions 10 are provided in such a manner that the distance between them is increased toward the front. As shown in FIG. 1, rotatable pulleys 17 are provided at the upper end portions (front end portions) of the left and right arm portions 10, respectively.

  As shown in FIGS. 1, 2, etc., each suspended rope-like body 11 is provided with a cylindrical outer 18 and an inner wire 19 partially covered by the outer 18. Each inner wire 19 has one end portion fixed to the reel mechanism 13, a midway portion spanned over a pulley 17 of the arm portion 10, and a hand portion 12 attached to the other end portion. Each outer 18 covers a portion of the corresponding inner wire 19 from the vicinity of the reel mechanism 13 to the vicinity of the pulley 17 of the arm portion 10.

  As shown in FIG. 2, the left and right hand portions 12 are symmetrical to each other. Each of the left and right hand portions 12 can support the load by hooking it on the handle portion of the load. The left and right hand portions 12 are respectively suspended by two inner wires 19. One of the two inner wires 19 takes charge of the load engaged with the hand portion 12. On the other hand, the remaining one of the two inner wires 19 is basically not tensioned, and when one of the inner wires 19 responsible for the load has a problem, it takes charge of the load and prevents the load from falling. It has become a thing.

  As shown in FIGS. 1 and 2, stoppers 20 that restrict excessive winding of the inner wire 19 are provided above the left and right hand portions 12, respectively.

  The lifting motor 14 shown in FIGS. 1, 2, and 4 is an electric motor, and is driven using electric power supplied from the battery 5 based on a command from the control device 4. The power of the elevating motor 14 is changed (decelerated) by the speed change mechanism 15 and the reel mechanism 13 is rotationally driven by the changed speed. By rotating and driving the reel mechanism 13, the inner wire 19 is wound and fed out, and thereby the left and right hand portions 12 that support the load are raised and lowered.

  The electromagnetic brake 16 shown in FIGS. 1, 2, and 4 is configured as a so-called negative brake that exhibits a braking force when not energized. In other words, the electromagnetic brake 16 exerts a braking force in the absence of power supply from the battery 5 to prevent the reel mechanism 13 from rotating and prevent the right and left hand portions 12 from being raised and lowered. When the electric power is supplied from the motor, the application of the braking force is canceled to allow the reel mechanism 13 to rotate and allow the left and right hand portions 12 to be raised and lowered.

  As shown in FIG. 2, the reel mechanism 13, the elevating motor 14, the speed change mechanism 15, and the electromagnetic brake 16 are attached to the upper rear surface of the support frame 7 in a collective manner. The control device 4 is attached to the rear surface of the intermediate portion below the parts related to the arm assist device 2 in the support frame 7. The battery 5 is attached to the lower rear surface of the support frame 7 located below the control device 4.

  The arm assist device 2 is configured to assist between an upper limit height and a lower limit height set for the height of the hand portion 12 (load). That is, the arm assist device 2 is configured to assist in the height range set for the height of the hand portion 12 (load). The arm assist device 2 basically keeps the reel mechanism 13 in position so that the height of the hand portion 12 (load) is maintained by the action of the electromagnetic brake 16 while the assist is not performed. It has become.

[About waist assist device]
The waist assist device 3 shown in FIGS. 1 to 3 and the like can assist an operator's standing up motion and the like. The waist assist device 3 has a pair of left and right base cases 21, left and right leg motors 22, and leg arms 23 attached to the front ends of the base cases 21 so as to be swingable around a horizontal axis P in the left-right direction. A leg belt 25 having a surface fastener 24 attached to each leg arm 23 is provided.

  As shown in FIG. 3, the base case 21 is substantially L-shaped when viewed from above. As shown in FIG. 2, the left and right base cases 21 have substantially bilaterally symmetrical shapes. As shown in FIGS. 1, 2, and 4, each base case 21 has a leg motor 22 that drives the leg arm 23, and a drive mechanism that decelerates the power of the leg motor 22 and transmits it to the leg arm 23. And are each housed. As shown in FIG. 1, the left and right leg belts 25 are attached to the operator's legs by wrapping around the operator's thighs and engaging the surface fastener 24. By driving the left and right leg motors 22, the corresponding leg arms 23 can be swung with respect to the base case 21. The driving force of each leg motor 22 is transmitted to the operator's thigh via the corresponding leg arm 23 and leg belt 25.

  Each of the left and right leg motors 22 is an electric motor including, for example, a servo motor. The left and right leg motors 22 are driven using electric power supplied from the battery 5 based on commands from the control device 4.

  The waist assist device 3 is configured to assist between an upper limit angle and a lower limit angle set for the arm angle of the leg arm 23 (relative angle of the leg arm 23 with respect to the base case 21). That is, the waist assist device 3 is configured to assist in the angle range set for the arm angle of the leg arm 23. The waist assist device 3 allows the leg arm 23 to swing while not assisting.

[Up and down switches]
As shown in FIG. 1 and FIG. 2, a lifting switch 26 is provided on one hand (right side) of the left and right hand parts 12, and the other hand (left side) of the left and right hand parts 12. 12 is provided with a lowering switch 27. The up switch 26 and the down switch 27 are connected to the control device 4. The raising switch 26 is operated when lifting the load, and the lowering switch 27 is operated when lowering the load. Based on the operation of the ascending switch 26 or the descending switch 27, the arm assist device 2 and the waist assist device 3 are cooperatively driven. If both the ascending switch 26 and the descending switch 27 are pressed simultaneously, the operations of the ascending switch 26 and the descending switch 27 are both invalidated.

  As shown in FIGS. 1 to 3, a right switch case 36 is provided on the right outer side of the right base case 21. As shown in FIGS. 2 and 3, a left switch case 40 is provided on the left outer side of the left base case 21. The left switch case 40 and the right switch case 36 are arranged in a left-right manner with the main body 1 as the center. On the upper surface side of the right switch case 36, switches such as a push-type power switch 38 are provided. Also, the left switch case 40 is provided with switches having different functions from the switches provided in the right switch case 36.

  As shown in FIG. 4, the assist suit includes a lift motor sensor 42 that detects the rotational speed of the lift motor 14 and a feed sensor that detects the feed amount of the inner wire 19 based on the rotational speed of the reel mechanism 13. 43, a leg motor sensor 44 for detecting the rotation speed of the leg motor 22, a leg angle sensor 45 for detecting the arm angle of the leg arm 23, and the like.

  As shown in FIG. 4, each of the leg motor sensor 44 and the lifting motor sensor 42 is composed of, for example, a rotary encoder. Each of the leg angle sensor 45 and the feeding sensor 43 is composed of, for example, a potentiometer. Output signals of the lift motor sensor 42, the feed sensor 43, the leg motor sensor 44, and the leg angle sensor 45 are input to the control device 4.

[About detection sensor]
As shown in FIG. 4, the assist suit is provided with a detection sensor B capable of detecting attachment to an operator as a sensor different from the sensors. As the detection sensor B, a back sensor 28 capable of detecting the pressing force applied by the operator's back when worn, a tension sensor 30 capable of detecting the tension of the shoulder belt 8, and a pressing force applied by the operator's waist when worn. A waist sensor 31 and an engagement sensor 35 capable of detecting the engagement of the pair of belt portions 33 are provided.

  The back sensor 28 is disposed on the back side of the back pad 29 opposite to the worker's back. The back sensor 28 is constituted by, for example, a pressure-sensitive sensor.

  The tension sensor 30 is constituted by, for example, a tension sensor.

  The waist sensor 31 is disposed on the back side of the waist pad 32 opposite to the operator's waist. The waist sensor 31 is composed of, for example, a pressure-sensitive sensor.

  The engagement sensor 35 is provided in the buckle portion 34. The engagement sensor 35 is configured by, for example, a contact type sensor.

[About control configuration]
As shown in FIG. 4, the control device 4 includes a power supply unit 47 that turns on and off the power supply from the battery 5, a monitoring unit 48 that monitors an input signal from the detection sensor B, and a control unit that performs drive control of the drive device A. 49 etc. are provided.

  Based on the operation of the power switch 38, the power supply unit 47 can switch between an on state in which the power of the battery 5 can be supplied to each element and a disconnected state in which the power of the battery 5 is not supplied to each element.

  When there is an input signal from the detection sensor B (when wearing by an operator is detected), the monitoring unit 48 outputs a drive permission signal to the control unit 49 and there is no input signal from the detection sensor B. In the case (when wearing by an operator is not detected), a drive prohibition signal is output to the control unit 49.

  The control unit 49 uses the power of the battery 5 based on the operation input of the ascending switch 26 and the descending switch 27, and for the legs 14 of the waist assist device 3 and the lifting motor 14 and the electromagnetic brake 16 of the arm assist device 2. The drive of the motor 22 is controlled.

  The control unit 49 allows the driving device A to be driven when the detection sensor B detects the mounting on the worker, and when the detection sensor B does not detect the mounting on the worker, It is comprised so that a drive may be prohibited. The control unit 49 detects that the attachment to the worker is detected by the detection sensor B based on the drive permission signal input from the monitoring unit 48. Further, the control unit 49 detects that the attachment to the worker is not detected by the detection sensor B based on the drive prohibition signal input from the monitoring unit 48.

[Basic operation mode of assist suit]
A basic operation mode of the assist suit having the above structure will be described.
For example, when lifting a load placed on the ground or floor and transferring it to a high place, first, the lowering switch 27 is continuously pressed. As a result, the inner wire 19 is fed out from the reel mechanism 13 in the arm assist device 2 to lower the left and right hand portions 12 and the left and right hand portions 12 are lowered to some extent. Driven in the direction of bending the part, the operator's squatting action is assisted. After the left and right hand portions 12 are hooked on the load, the raising switch 26 is continuously pressed. As a result, the left and right hand portions 12 in a state where the inner wire 19 is wound around the reel mechanism 13 and supports the load in the arm assist device 2 are raised, and the leg arms 23 of the waist assist device 3 are bent in the direction of bending the knee. It is driven to assist the worker's rising motion. Thus, the muscle strength of the operator's arm is assisted by the arm assist device 2, and the muscle strength of the operator's legs and waist is assisted by the waist assist device 3, so that the load can be easily lifted.

  When the pressing operation of the raising switch 26 is stopped and the raising operation of the hand portion 12 is stopped, the braking force of the electromagnetic brake 16 is exerted, and the left and right hand portions 12 supporting the load are maintained at a desired height. The When the assist of the waist assist device 3 is completed, the leg arm 23 is in a swingable state. Before the left and right hand portions 12 in the arm assist device 2 are raised to the upper limit position, the assisting of the rising motion by the waist assist device 3 is completed, so the left and right hand portions 12 supporting the load are raised to a desired height. In this state, the operator can freely walk and move the load to a predetermined place without using much muscle strength of the arm.

  And when placing a load in a predetermined place, the lowering switch 27 is continuously pressed. As a result, the inner wire 19 is fed out from the reel mechanism 13 in the arm assist device 2, and the left and right hand portions 12 supporting the load are lowered. When the height for placing the load is low, the waist assist device 3 is also driven to assist the operator's squatting action. When the load is placed at a predetermined location, the load transfer operation is completed.

  The operation of the assist suit is executed only when the worker wears the assist suit and the detection sensor B is in the detection state, and the worker does not wear the assist suit and the detection sensor B is not turned on. It is not executed when it is in the detection state. As a result, malfunctions when the assist suit is not worn can be prevented, and the assist suit that is placed falls over due to a malfunction of the drive device A when the assist suit is not worn, or the worker wears the assist suit. It is possible to avoid the occurrence of inconveniences such as unexpected operations during the process.

[Another embodiment]
Hereinafter, another embodiment in which the above embodiment is modified will be described. The following other embodiments can be applied in combination with the above embodiment as long as no contradiction arises. The scope of the present invention is not limited to the contents shown in each embodiment.

(1) In the above embodiment, the back sensor 28 is disposed on the back side of the back pad 29 opposite to the worker's back, but the present invention is not limited thereto. For example, the back sensor 28 may be built in the back pad 29, or may be provided on the front side of the back pad 29 (where it touches the operator's back).

(2) In the above embodiment, the waist sensor 31 is disposed on the back side of the waist pad 32 opposite to the operator's waist, but the present invention is not limited thereto. For example, the waist sensor 31 may be incorporated in the waist pad 32, or may be provided on the front side of the waist pad 32 (a location that contacts the waist of the operator).

(3) In the above-described embodiment, the back sensor 28 configured by a pressure-sensitive sensor, the tension sensor 30 configured by a tension sensor, the waist sensor 31 configured by a pressure-sensitive sensor, and a contact-type sensor Although the engagement sensor 35 comprised by the sensor is illustrated, it is not restricted to this. The detection methods of the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35 may be other methods, respectively.

(4) In the above-described embodiment, only when the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35 are in the detection state, the control unit 49 allows the drive device A to be driven. However, the present invention is not limited to this. For example, if at least one of the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35 is in a detection state, the drive of the driving device A by the control unit 49 may be permitted.

(5) In the embodiment described above, the detection sensor B includes the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35, but is not limited thereto. Any of the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35 may not be provided. In other words, it is sufficient that at least one of the back sensor 28, the tension sensor 30, the waist sensor 31, and the engagement sensor 35 is provided. Further, as the detection sensor B, for example, another sensor such as a leg sensor for detecting the wearing of the leg belt 25 may be provided.

(6) In the above embodiment, the monitoring unit 48 provided in the control device 4 monitors the signal of the detection sensor B, and whether to allow or prohibit the driving of the driving device A by the control unit 49 based on the monitoring result. However, the present invention is not limited to this. For example, instead of such a monitoring unit 48, a relay circuit that is in a conductive state when the detection sensor B is in a detection state and is in a cutoff state when the detection sensor B is in a non-detection state is replaced with the lift switch 26 and the control device 4. It may be provided in the middle of the path connecting the two and the path connecting the lowering switch 27 and the control device 4. In this case, when the detection sensor B is in the non-detection state, the relay circuit is cut off, and the operation signals of the up switch 26 and the down switch 27 are not input to the control device 4, and the up switch 26 and the down switch when not mounted The operation input of the switch 27 becomes invalid, and the drive of the driving device A by the control unit 49 is prohibited.

(7) In the above embodiment, the drive device A is exemplified as having two types of the waist assist device 3 and the arm assist device 2, but is not limited thereto. For example, as the driving device A, only one of the waist assist device 3 and the arm assist device 2 may be provided.

(8) In the above embodiment, the load is exemplified as the object, but the present invention is not limited to this. For example, the object may be a crop planted in a field. In this case, for example, the crop can be pulled out from the field and lifted using the assist of the arm assist device 2.

(9) The left and right structures may be reversed from the above embodiment.

  INDUSTRIAL APPLICABILITY The present invention can be used for an assist suit capable of assisting an operator in raising and lowering an object.

8: Shoulder belt 28: Back sensor 29: Back pad 30: Tension sensor 31: Waist sensor 32: Waist pad 33: Belt part 34: Buckle part 35: Engage sensor 49: Control part A: Drive device B: Detection sensor

Claims (7)

A driving device capable of assisting the operation of the worker;
A control unit that performs drive control of the drive device;
A detection sensor capable of detecting attachment to an operator,
The control unit allows the drive device to be driven when the detection sensor detects that the worker is wearing, and when the detection sensor detects that the worker is not worn, Assist suit configured to prohibit driving.   The assist suit according to claim 1, wherein a back sensor capable of detecting a pressing force applied by a worker's back when worn is provided as the detection sensor. There is a back pad that comes into contact with the back of the operator when worn,
The assist suit according to claim 2, wherein the back sensor is disposed on the back side of the back pad opposite to the back of the operator. A shoulder belt is provided around the operator's shoulder,
The assist suit according to any one of claims 1 to 3, wherein a tension sensor capable of detecting a tension of the shoulder belt is provided as the detection sensor.   The assist suit as described in any one of Claims 1-4 with which the waist sensor which can detect the pressing force by the operator's waist | hip | lumbar part at the time of mounting | wearing is provided as said detection sensor. A waist pad that comes into contact with the operator's waist when worn is provided,
The assist suit according to claim 5, wherein the waist sensor is disposed on the back side of the waist pad opposite to the operator's waist. A waist belt that can be wound around and attached to the waist of an operator by engaging a pair of belts with each other is provided.
The assist suit according to any one of claims 1 to 6, wherein an engagement sensor capable of detecting engagement of a pair of the belt portions is provided as the detection sensor.

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