JP2008079371A - Twisted string type actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize a light-weight, space-saving and low noise actuator using a small motor. <P>SOLUTION: The twisted string type actuator is constituted of a twisted string 1 having a structure of loosely twisting two strings 11, 12 together and a motor 2. One end side of the twisted string 1 is connected to a knuckle FJ1 and the other end side is connected to the rotary shaft 21 of the motor 2 via a power transmission mechanism 4. When the rotary shaft 21 of the motor 2 is rotated, the twisting strength of the two strings 11, 12 constituting the twisted string 1 is strengthened or loosened corresponding to the rotating direction, to shorten or increase the length of the twisted string 1, resultantly causing the knuckle FJ1 to rotate centering around the axial center AX1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an actuator applicable to a motor-driven artificial hand, a robot hand, and the like, and more particularly to a twisted string actuator using a twisted string having a structure in which two strings are twisted together and a motor.

  Conventionally, as an actuator using a wire and a motor (hereinafter referred to as a wire actuator), for example, one described in Patent Document 1 or 2 is known. FIG. 8 shows a basic concept of a configuration that is considered to be a related art close to the present invention among various wire actuators for a finger joint using a wire or string (hereinafter simply referred to as a string) and a motor.

  In FIG. 8, a rotating body 102 such as a pulley is connected to a rotating shaft 101a of a motor 101 via a speed reducer. Alternatively, the rotating body 102 is directly connected to the rotating shaft 101a of the motor 101 with a built-in reducer. One string 103, 104 is connected to each of two locations facing the radial direction of the rotating body 102, and the other end of each string 103, 104 is connected to the finger joint 105.

When the rotating shaft 101a of the motor 101 rotates, the rotating body 102 rotates slowly, and the two strings 103 and 104 are driven in opposite directions. That is, one is pulled and the other is loosened. As a result, the finger joint 105 is driven to rotate about the axis AX.
Japanese Patent Laid-Open No. 06-008178 Japanese Patent Application Laid-Open No. 07-096485

  When using a wire actuator as described above for a motor-driven prosthetic hand or robot hand having many joints, one motor is required for each joint. It is necessary to use a motor. On the other hand, in order to ensure a certain level of gripping force required for a motor-driven artificial hand, a robot hand, or the like, a minimum output torque is required for a drive system including a motor and a speed reducer.

  Even with a small motor, it is possible to obtain a large torque by using a speed reducer. However, since the speed reducer itself increases the weight of the device, for example, the tip of the prosthesis (hand) becomes heavy. Problems arise. Furthermore, since a space for incorporating a reduction gear is required, it is difficult to realize a small and lightweight motor-driven artificial hand or robot hand.

  In addition, when using a gear type speed reducer incorporating a plurality of speed reduction gears, there is a problem of noise generated at the meshing portion of the gears when the gears rotate in addition to the weight and space problems. .

  In view of the above-described conventional problems, an object of the present invention is to realize a lightweight, space-saving, low-noise actuator using a small motor.

  The actuator according to the present invention is a twisted string type actuator using a twisted string having a structure in which two strings are twisted together and a motor, wherein one end side of the twisted string is connected to an object to be driven, and the twisted string When the other end side of the motor is connected to the rotating shaft of the motor directly or via a power transmission mechanism and the rotating shaft of the motor rotates, the twist of the two strings constituting the twisted string according to the rotating direction The length of the twisted string is shortened or extended by being strengthened or loosened, and as a result, the driven object is driven (Claim 1). .

  According to such a configuration, the twisted string converts rotational motion (rotational force) in the twist direction into linear motion (tension) in the length direction, and functions as power transmission means including a speed reduction mechanism. Therefore, a speed reducer using a multi-stage gear or the like is not necessary, which can greatly contribute to reducing the size and weight of the entire apparatus. Further, there is no noise generated by a reduction gear using a multistage gear or the like, and a silent actuator can be realized. In general, a twisted string is less expensive than a speed reducer using a multistage gear or the like, so that the cost of the actuator can be reduced.

  Furthermore, since there is a certain degree of flexibility (flexibility) and elasticity between the rotational movement in the twist direction of the twisted string and the linear movement in the length direction, it is not necessary to use an elastic biasing means such as a spring or an air cylinder. However, it is possible to realize a so-called soft actuator. Thereby, for example, a compliance function like a human hand can be easily realized.

  In a preferred embodiment of the present invention, in order to regulate the drive direction and drive range of the drive object, the slide member is movable within a predetermined range along a slide guide, and one end side of the twisted string is the slide member. Is connected to the driven object via the (Claim 2).

  According to such a structure, the drive direction and drive range of a drive target object can be easily controlled with a slide guide and a slide member. In addition, design flexibility regarding the distance and direction between the motor and the object to be driven can be secured, making it easier to meet the restrictions on the space where the actuator is mounted and making effective use of the space possible. become.

  In another preferred embodiment of the present invention, the drive object is a finger joint rotatable about an axis, and two sets of actuator kits including the twisted string and the slide member are provided, and the finger joint One end sides of the twisted strings of the two sets of actuator kits are respectively connected to the two locations facing each other across the shaft center via the slide member.

  According to such a configuration, the twisted strings of the two sets of actuator kits are driven in opposite directions, that is, one of the twisted strings is driven in a shortening direction, and the other is driven in an extending direction. Thus, the finger joint can be driven easily and accurately.

  As a more preferable configuration in the above embodiment, the other end side of the twisted strings of the two sets of actuator kits is connected to two different output shafts of the power transmission mechanism connected to the rotation shaft of the motor, When the rotating shaft of the motor rotates, one of the two output shafts rotates in a direction to increase the twist of the twisted string connected thereto, and the other in a direction to loosen the twist of the twisted string connected thereto. It is comprised so that it may rotate (Claim 4).

  According to such a configuration, the twist kit can be driven by one motor while using an actuator kit including two sets of twist cords for one finger joint. Drive control is simpler than when individually driven. In addition, the finger joint can be driven quickly.

  According to the twisted string actuator of the present invention, a twisted string having a structure in which two strings are twisted together drives a finger joint or the like by shortening or extending in accordance with the rotation direction of the motor. The string functions as power transmission means including a speed reduction mechanism. Therefore, a speed reducer using a multi-stage gear or the like is not necessary, which can greatly contribute to the reduction in size and weight of the entire apparatus. Further, there is no noise generated by a reduction gear using a multistage gear or the like, and a silent actuator can be realized. As described above, the effect that the compliance function can be easily realized is also obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, when describing the positional relationship and direction of each member vertically and horizontally, it means the positional relationship and direction in the drawings to the last, and it means the positional relationship and direction when incorporated in an actual device. is not.

  FIG. 1 is a schematic diagram showing the concept of a twisted string actuator according to the present invention. As shown in FIG. 1, the twisted string actuator according to the present invention uses a twisted string 1 and a motor 2 having a structure in which two strings or wires (hereinafter simply referred to as strings) 11 and 12 are loosely twisted together. Composed. FIG. 1A schematically shows a state in which the twisting of the two cords 11 and 12 is loosened to form two parallel cords, and FIG. 12 schematically shows a state in which 12 are twisted together. One end side of the twisted string 1, that is, the two strings 11, 12 is connected (fixed) to the driving object OB, and the other end side is connected (fixed) to the rotating shaft 21 of the motor 2.

  The length of the twisted cord 1 in the state shown in FIG. 1 (a) is L, and the rotating shaft 21 of the motor 2 rotates from this state to constitute the twisted cord 1 as shown in FIG. 1 (b). When the two cords 11 and 12 are twisted together, the length of the twisted cord 1 is L−ΔL. That is, when the two cords 11 and 12 are twisted together, the length of the twisted cord 1 is shortened by ΔL. As a result, the driving force F in the direction (right direction) attracted to the motor 2 by the tension of the twisted string 1 acts on the driving object OB. Therefore, the twisted string 1 has a function of converting the rotational motion in the twisted direction (the rotational force of the motor 2) into the linear motion (tension) in the lengthwise direction.

  When the rotating shaft 21 of the motor 2 rotates in the direction opposite to the above from the state of FIG. 1B, the twist of the two cords 11 and 12 constituting the twisted cord 1 is loosened. At this time, although not shown in FIG. 1, if it is assumed that the object OB is urged leftward by an urging means such as a tension spring, the object OB moves away from the motor 2 by the urging force (left Direction) and the length of the twisted string 1 is extended. It can be seen that the length of the twisted cord 1 is the longest value (L) in the state of FIG. 1A in which the twisting of the two cords 11 and 12 is loosened to form two parallel cords. .

  Therefore, according to the twisted string actuator of the present invention using the twisted string 1 and the motor 2 having a structure in which the two strings 11 and 12 are loosely twisted together, according to the rotation direction of the rotating shaft 21 of the motor 2. The twist of the two cords 11 and 12 constituting the twisted cord 1 is strengthened or loosened, so that the length of the twisted cord 1 is shortened or extended, and as a result, the drive object OB is set within a predetermined range. It is possible to drive within.

  Since the twisted string 1 functions as power transmission means including a speed reduction mechanism, a speed reducer using a multi-stage gear or the like is not required, and can greatly contribute to reduction in size and weight of the entire apparatus. In addition, there is no noise generated by a reduction gear using a multistage gear or the like, and a silent actuator can be realized. In general, a twisted string is less expensive than a speed reducer using a multistage gear or the like, so that the cost of the actuator can be reduced.

  Further, since there is a certain degree of flexibility and elasticity between the rotational movement in the twist direction and the linear movement in the length direction of the twisted string 1, it is not necessary to use an elastic biasing means such as a spring or an air cylinder. However, it is possible to realize a so-called soft actuator. Thereby, for example, a compliance function like a human hand can be easily realized.

  FIG. 2 is a schematic view showing an embodiment of a twisted string actuator according to the present invention. In the description of this embodiment and the embodiments described later, the finger joint FJ that can rotate about the axis AX corresponds to the driving object. As shown in FIG. 2, in order to regulate the driving direction and driving range of the finger joint FJ as a driving object, a slide member 32 that is movable within a predetermined range along the slide guide 31 is provided, and the twisted string 11 is provided. Is connected to the finger joint FJ through the slide member 32.

  In addition, two sets of actuator kits including the twisted string 1 and the slide member 32 are provided, and one end side of the twisted string 1 of the two sets of actuator kits is connected to two locations P1 and P2 facing each other across the axis AX of the finger joint FJ. Each is connected via a slide member 32.

  In the configuration of the present embodiment, the driving direction and driving range of the finger joint FJ that is the driving object can be easily regulated by the slide guide 31 and the slide member 32. In addition, since design flexibility regarding the distance and direction between the motor 2 and the finger joint FJ can be secured, it becomes easy to cope with the limitation of the space where the actuator is mounted, and the effective use of the space is facilitated. It becomes possible. In FIG. 2, the driving direction of the finger joint FJ and the axial center direction of the rotating shaft 21 of the motor 2 are substantially the same. However, by bending the flexible twisted string 1 using, for example, a pulley or the like, both directions are changed. It is also possible to configure it to be 90 degrees different. It is also possible to bring the finger joint FJ and the motor 2 closer to or away from each other.

  Further, by driving the twisted cords 1 of the two sets of actuators in opposite directions, for example, as shown in FIG. 2, the upper twisted cord 1 is driven in a shortening direction, and the lower twisted cord 1 is driven. Is driven in the direction of stretching. Thereby, the finger joint FJ can be driven easily and accurately. In the configuration shown in FIG. 2, two motors 2 are used to individually drive the twisted strings 1 of two sets of actuator kits. In this configuration, it is necessary to control driving of the two motors 2 in synchronization. It is also preferable to provide an interlock circuit that prevents only one motor 2 from operating. In order to simplify such control and circuit, the twisted string 1 of two sets of actuator kits may be driven simultaneously using one motor as in the embodiment described later.

  FIG. 3 is a schematic diagram showing an application example of the twisted string actuator shown in FIG. 2 to a plurality of finger joints. A state in which two finger joints FJ1 and FJ2 are pivotally connected by an axis AX1 is shown. The finger joint FJ1 can rotate about the axis AX1, and the finger joint FJ2 can rotate about the axis AX2. Although omitted in FIG. 3, the finger joint FJ2 is also provided with two sets of actuator kits including the twisted string 1 and the slide member 32 in two positions opposite to each other with the axis AX2 interposed therebetween, similarly to the finger joint FJ1. One end side of the twisted string 1 of the two sets of actuator kits is configured to be connected via a slide member 32. In this way, two twisted strings 1 are used for one joint, and in the case of n joints, 2n twisted strings 1 are used.

  FIG. 4 is a schematic view showing another embodiment of the twisted string actuator according to the present invention. In this embodiment, in the configuration shown in FIG. 2 or FIG. 3, the twisted cords 1 of two sets of actuator kits are driven simultaneously using one motor. That is, the other end side (motor side) of the twisted string 1 of the two sets of actuator kits is connected to two different output shafts 41 and 42 of the power transmission mechanism 4 connected to the rotating shaft 21 of the motor 2. Yes. When the rotating shaft 21 of the motor 2 rotates, the upper first output shaft 41 rotates in a direction to increase the twist of the twisted string 1 connected thereto, and the lower second output shaft 42 twists connected thereto. It is comprised so that it may rotate in the direction which loosens the twist of a string.

  In this configuration, while using an actuator kit including two sets of twisted cords 1 for one finger joint FJ1, the twisted cords 1 are simultaneously driven by one motor 2, so that the two motors individually Drive control is simpler than in the case of driving. In addition, the finger joint FJ1 can be driven quickly.

  In the configuration shown in FIG. 4, a speed reduction mechanism using three spur gears 43, 44 and 45 is used as the power transmission mechanism 4. The central flat gear 43 is fixed to the rotating shaft 21 of the motor 2, the upper flat gear 44 is fixed to the first output shaft 41 to which the upper twisted string 1 is connected, and the lower flat gear 45 is The twisted string 1 is fixed to the second output shaft 42 connected thereto. Since the upper flat gear 44 and the lower flat gear 45 rotate in the same direction (both directions opposite to the central flat gear 43), the twisting directions of the twisted cords 1 of the two sets of actuator kits are opposite to each other. It is necessary to keep.

  That is, when the rotating shaft 21 of the motor 2 rotates, the first output shaft 41 and the second output shaft 42 rotate in the same direction (both directions opposite to the rotating shaft 21 of the motor 2). Since the twisting directions are opposite to each other, for example, as shown in FIG. 4, the upper twisted string 1 is driven in a direction to increase the twist (the direction in which the length is shortened), and the lower twisted string 1 is twisted. Driven in the loosening direction (the direction in which the length extends).

  By changing the number and combination of the gears constituting the power transmission mechanism 4, the power transmission mechanism 4 is configured so that the rotation directions of the two output shafts 41 and 42 are opposite to each other, and two upper and lower twisted strings One twist direction may be the same as each other. In short, when the rotating shaft 21 of the motor 2 rotates, one of the first output shaft 41 and the second output shaft 42 rotates in a direction to increase the twist of the twisted string 1, and the other in a direction to loosen the twist of the twisted string. What is necessary is just to comprise the power transmission mechanism 4 and the twisted string 1 so that it may rotate. However, it is desirable to configure the power transmission mechanism 4 so that the output torques of the first output shaft 41 and the second output shaft 42 are equal to each other, or so that both are balanced.

  Further, in order to avoid the generation of noise at the meshing portion between the gears, the power transmission mechanism 4 is configured by using a plurality of rollers or rollers and belts that transmit power by the frictional force of the contact surface instead of the gears. May be. It is also desirable to reduce noise generated from the motor 2 by using a DC brushless motor as the motor 2.

  FIG. 5 is a schematic diagram showing a state in which the twisted string actuator of FIG. 4 is driven to one limit of the driving range. As described above, the drive range of the twisted string actuator (that is, the drive range of the finger joint FJ1) is determined by the movable range of the slide member 32 that can move along the slide guide 31.

  In the state shown in FIG. 5, the slide member 32 connected to the upper twisted string 1 has moved to the right limit of the movable range, and conversely, the slide member 32 connected to the lower twisted string 1 is within the movable range. It has moved to the left limit. This state is the right rotation limit of the driving range of the finger joint FJ1 that can rotate around the axis AX1.

  In this state, the upper twisted string 1 has the shortest length in the driving range (the most twisted state), and the lower twisted string 1 has the longest length in the driving range (the most untwisted state). is there. At the left rotation limit of the driving range of the finger joint FJ1, the relationship is opposite to the above. Within the required rotational drive range of the finger joint FJ1, the initial twist amount of the twisted cord 1 so that the rotation amount of the output shafts 41 and 42 and the amount of expansion / contraction of the upper and lower twisted cords 1 are as linear as possible. Is set.

  FIG. 6 is a schematic diagram showing an example in which the twisted string actuator according to the present invention is used as a multi-joint finger joint actuator. Two sets of actuator kits including the twisted string 1 and the slide member 32 as shown in FIG. 5 and the twisted string type actuator 5 including one motor 2 and the power transmission mechanism 4 are respectively connected to the finger joints FJ1, FJ2,. . . A state in which FJn is connected one by one is schematically shown. If the twisted string actuators 5 are used by the number n of the finger joints to be moved, the respective finger joints can be individually driven by controlling the motors 2 of the twisted string actuators 5.

  FIG. 7 is a schematic diagram showing an example of using three twisted string actuators according to the present invention to drive three finger joints constituting one finger. Three twisted string actuators 5A, 5B, and 5C for individually driving the three finger joints FJ1, FJ2, and FJ3 are provided, and the motors 2A, 2B, and 2C of the twisted string actuators are driven and controlled by the controller 6. The The controller 6 is configured using, for example, a microcomputer.

  The controller 6 twists connected to the respective finger joints via slide members 32A, 32B, and 32C in accordance with angles (target drive angles) θ1, θ2, and θ3 that the finger joints FJ1, FJ2, and FJ3 are to be driven. The target expansion / contraction amounts ΔLA, ΔLB, ΔLC of the strings 1A, 1B, 1C are calculated. Further, the controller 6 controls the motor 2A connected to each twisted string via the power transmission mechanisms 4A, 4B, 4C according to the calculated target expansion / contraction amounts ΔLA, ΔLB, ΔLC of the twisted strings 1A, 1B, 1C. The target rotation angles φ1, φ2, and φ3 of the rotation axes 21A, 21B, and 21C of 2B and 2C are calculated. And the drive signal corresponding to those target rotation angles is output to each motor 2A, 2B, 2C.

  When the rotation shafts 21A, 21B of the motors 2A, 2B, 2C are rotated by the target rotation angles φ1, φ2, φ3 according to the drive signal, the pair of output shafts 41A of the respective power transmission mechanisms 4A, 4B, 4C are accordingly transmitted. And 42A, 41B and 42B, 41C and 42C rotate, and the twisted strings 1A, 1B and 1C of the twisted string actuators 5A, 5B and 5C expand and contract by the target expansion / contraction amounts ΔLA, ΔLB and ΔLC. As a result, the pair of slide members 32A, 32B, and 32C of the twisted string actuators 5A, 5B, and 5C move in the opposite directions by the target displacement amount, and the finger joints FJ1, FJ2, and FJ3 have the target drive angles θ1, θ2 , Θ3.

  As mentioned above, although several embodiment of this invention was described, this invention is not restricted to said embodiment, It is possible to implement with a various form. The twisted string actuator according to the present invention is not limited to finger joints such as motor-driven artificial hands and robot hands, but can be applied to wrist joints and other various joints. Furthermore, the present invention is not limited to a rotational motion such as a joint, and the twisted string actuator of the present invention can be used as an actuator for a member that reciprocates.

It is a schematic diagram which shows the concept of the twisted string type actuator by this invention. It is a mimetic diagram showing one embodiment of a twisted string type actuator by the present invention. It is a schematic diagram which shows the example of application to the multiple finger joint of the twisted string type actuator shown in FIG. It is a schematic diagram which shows another embodiment of the twisted string type actuator by this invention. FIG. 5 is a schematic diagram illustrating a state in which the twisted string actuator of FIG. 4 is driven to one limit of a driving range. It is a schematic diagram which shows the example which uses the twisted string type actuator by this invention as a multi-joint finger joint actuator. It is a schematic diagram which shows the example in the case of using the three twisted string type actuators by this invention and driving the three finger joints which comprise one finger. It is a schematic diagram which shows the basic concept of the structure of the wire type actuator which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Twist string 2 Motor 4 Power transmission mechanism 11, 12 Two strings which comprise a twist string 21 Motor rotating shaft 31 Slide guide 32 Slide member 41, 42 Two output shafts OB, FJ, FJ1 of a power transmission mechanism Object (finger joint)

Claims (4)

A twisted string actuator using a twisted string and a motor having a structure in which two strings are twisted together,
One end side of the twisted string is connected to an object to be driven, and the other end side of the twisted string is connected directly to the rotating shaft of the motor or via a power transmission mechanism,
When the rotation shaft of the motor rotates, the length of the twisted string is shortened or extended by strengthening or loosening the twist of the two strings constituting the twisted string according to the rotation direction. As a result, the twisted string actuator is configured such that the driven object is driven. In order to regulate the drive direction and drive range of the drive object, a slide member that is movable within a predetermined range along a slide guide is provided, and one end side of the twisted string is connected to the drive object via the slide member. The twisted string actuator according to claim 1, wherein the twisted string actuator is connected. The driving object is a finger joint that can rotate around an axis, and two sets of actuator kits including the twisted string and the slide member are provided, and are arranged at two locations facing each other across the axis of the finger joint. The twisted string actuator according to claim 2, wherein one end sides of the twisted strings of the two sets of actuator kits are connected to each other via the slide member. The other ends of the twisted strings of the two sets of actuator kits are connected to two different output shafts of the power transmission mechanism connected to the rotation shaft of the motor, and when the rotation shaft of the motor rotates, the 2 One of the output shafts of the book is configured to rotate in the direction of increasing the twist of the twisted string connected thereto, and the other is configured to rotate in the direction of loosening the twist of the twisted string connected thereto. The twisted string actuator according to claim 3.

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