JP2009034774A - Joint mechanism with variable stiffness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint mechanism with variable stiffness capable of being mounted on a robot arm, highly durable and capable of reducing influence by deterioration of an elastic member. <P>SOLUTION: An arm comprises a forearm transmission mechanism 42 and a forearm model 3 and is provided on an upper arm 2 to be rotatable around a joint shaft 41a. The forearm transmission mechanism 42 has a center rail groove 42d and a side rail groove 42e extending in a longitudinal direction. The respective grooves 42d and 42e are provided at a predetermined distance in a vertical direction to the longitudinal direction of a model pipe 31 from the joint shaft 41a. Elastic members 43f have linearity and are provided on the upper arm 2 to be rotatable around the joint shaft 41a so that urging force is always directed to the shaft 41a. Each elastic member 43f is structured so that one end on the side of the joint shaft 41a slides along the respective grooves 42d and 42e to keep a distance between the other end and the shaft 41a constant when rotating around the shaft 41a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a joint mechanism having variable rigidity.

  In the conventional robot arm, the actuator is directly attached to the arm, so that when the arm receives an active or passive impact force, the impact force propagates to the actuator, causing deterioration or damage to the actuator. There was a problem. In order to solve this problem, it is conceivable to incorporate an elastic element between the actuator and the arm so that the impact force is absorbed by the elastic element and relaxed. However, simply incorporating an elastic element results in a soft joint, which makes it difficult to apply a force such as carrying a load. In addition, because of the soft joint, the hand becomes vibrating and fine work cannot be performed.

  Further, the robot is required to have high rigidity when performing force work. On the other hand, in the field of welfare and nursing care, physical contact with humans is involved, so it is desirable that the rigidity be as low as possible. Thus, the ability to arbitrarily change the joint stiffness is highly necessary for robots in the welfare field and the nursing field that may involve physical contact with humans. Therefore, it can be expected that the robot will be able to communicate smoothly with humans. Further, in an operation in which the robot receives an impact force from the outside, it is possible to protect the robot by reducing the rigidity and reducing the generated impact.

  Therefore, as a method for changing the rigidity of the joint of the robot, a method using software control or a mechanism using a combination of mechanical elements or material characteristics has been proposed. However, when the rigidity is changed by software, a general robot having a reduction gear with a high reduction ratio at the joint cannot realize low rigidity due to a high frictional force in the reduction gear. In addition, it is common practice to detect external force with a force sensor and change the apparent rigidity according to the detected force. However, it takes time to operate the robot after detecting the force with the force sensor. There is a delay and the momentary impact force cannot be mitigated.

  Therefore, by providing a variable rigidity mechanism on the output side of the speed reducer, it is possible to cope with a sudden impact without using software control, and it is possible to realize both high rigidity and low rigidity. As such, a rod-like elastic member is incorporated in a drive device (see, for example, Patent Document 1) that has a variable stiffness mechanism and is used as a part of a medical auxiliary instrument, and a mesh-like exterior tube member, There is a spring device (for example, refer to Patent Document 2) that allows easy adjustment of rigidity.

JP 2004-105609 A JP 2004-169795 A

  However, since the drive device described in Patent Document 1 is for knee joint rehabilitation and is used by being installed on the ground, it can be designed without being limited by the weight or size of the mechanism. For this reason, there has been a problem that it cannot be mounted on a mechanism such as a robot arm that is limited in weight or size. Moreover, although the spring device described in Patent Document 2 is excellent in terms of weight reduction, since the material is a flexible body, there is a problem that deterioration with respect to use time is remarkable and durability is inferior. Since the drive device described in Patent Document 1 and the spring device described in Patent Document 2 have a mechanism that makes the rigidity variable using a non-linear spring, deterioration due to fatigue of the spring directly affects the non-linear characteristics, As a result, there is also a problem that it affects the characteristic deterioration of the variable stiffness.

  The present invention has been made paying attention to such problems, and provides a joint mechanism having variable rigidity that can be mounted on a robot arm, has high durability, and can suppress the influence of deterioration of an elastic member. For the purpose.

  In order to achieve the above object, a joint mechanism having variable rigidity according to the present invention includes a support member, an arm, and an elastic member, and the arm is rotatable about a rotation axis perpendicular to the length direction. The elastic member has linearity, and exerts an urging force toward the rotating shaft on the arm, and the angle between the direction of the urging force and the arm can be changed. It is provided in a support member, and is configured such that the magnitude of the biasing force changes and the rigidity of the rotating shaft changes nonlinearly according to the angle formed by the direction of the biasing force and the arm. Features.

  Since the joint mechanism having variable rigidity according to the present invention has a simple configuration including a support member, an arm, and an elastic member, the weight and size of the joint mechanism can be reduced, and a robot arm or the like subject to weight or size restrictions can be used. It can be mounted as a joint mechanism. Since the magnitude of the biasing force acting on the arm changes according to the direction of the biasing force toward the rotating shaft by the elastic member and the angle formed with the arm, the rigidity of the rotating shaft changes nonlinearly. The rigidity of the rotating shaft, that is, the joint can be changed from high rigidity to low rigidity.

  In the case of a non-linear elastic member such as rubber, the output with respect to the input becomes non-linear, so that the output greatly changes with a slight input error or characteristic change. On the other hand, in the joint mechanism having variable rigidity according to the present invention, since the elastic member has linearity, the output changes linearly with respect to the input error or characteristic change, and the error can be easily estimated. . Further, since the direction of the biasing force acting on the arm by the elastic member changes, the rigidity of the rotating shaft, that is, the joint is changed, so that the influence of deterioration of the elastic member can be suppressed and the influence can be easily estimated. is there. The durability can be enhanced by using a durable coil spring or the like as the elastic member.

  In the joint mechanism having variable rigidity according to the present invention, the arm has a guide portion along a length direction, and the guide portion has a predetermined distance in a direction perpendicular to the length direction of the arm from the rotation shaft. The elastic member is formed of a compression spring, and is provided on the support member so as to be rotatable about the rotation axis so that the compression direction always faces the rotation axis, and when the rotation member rotates about the rotation axis. It is preferable that one end on the rotating shaft side slides along the guide portion, and the distance between the other end and the rotating shaft is kept constant. In this case, when the elastic member rotates about the rotation axis with respect to the arm, one end on the rotation axis side of the elastic member is provided at a predetermined distance from the rotation axis in a direction perpendicular to the length direction of the arm. The elastic member expands and contracts by sliding along the guide portion. Thereby, the magnitude | size of the urging | biasing force which acts on an arm changes, and the rigidity of a rotating shaft can be changed nonlinearly.

The principle of the joint mechanism having variable rigidity according to the present invention in this case will be described with reference to FIG.
As shown in FIG. 1A, the joint mechanism includes an arm a, an elastic member c made of a compression spring having linearity, and a mechanism that limits displacement of the elastic member c only to a straight line t passing through the rotation axis o. b and a slider d that pushes the arm a by the urging force of the elastic member c. The arm a and the elastic member c can rotate around the rotation axis o. The elastic member c is always directed to the rotation axis o by the mechanism b. The slider d provided at one end of the elastic member c on the rotating shaft o side slides on the straight line u along the guide portion along the length direction of the arm a by the mechanism b. The guide portion is provided along a straight line u on the arm a with a predetermined distance from the rotation axis o in a direction perpendicular to the length direction of the arm a. The other end of the elastic member c is held at a constant distance from the rotation axis o by the mechanism b.

  Hereinafter, a mechanism including the mechanism b, the elastic member c, and the slider d is referred to as a slider type pressurizing mechanism. An actuator is attached to the slider-type pressurizing mechanism, and the actuator can rotate the slider-type pressurizing mechanism about the rotation axis o. At this time, the distance between the mechanism b and the rotation axis o is always a constant length L. As shown in FIG. 1A, the slider-type pressurizing mechanism is adjusted so that the elastic member c has a natural length l in a state where the arm a and the straight line t that is the displacement direction of the elastic member c are orthogonal to each other. ing.

  Here, Δθ is a minute rotation angle of the arm a around the rotation axis o when the arm a receives a very small force, and Δτ is a torque change at that time. As shown in FIG. 1A, in the state where the arm a and the straight line t which is the displacement direction of the elastic member c are orthogonal to each other, the rigidity (Δτ / Δθ) around the rotation axis o of the arm a is zero. However, as shown in FIG. 1B, when the actuator is given a rotational displacement of φ around the point o by the actuator, the slider d slides along the guide portion and moves on the straight line u. , The elastic member c is compressed by the length of l−l ′. Due to the displacement of the elastic member c, the slider d applies a force to the arm a. Therefore, as shown in FIG. 1 (c), the rigidity (Δτ / Δθ) around the rotation axis o of the arm a is theoretically non-linear from 0 to infinity with respect to the rotational displacement φ of the slider type pressurizing mechanism. To change.

  In the joint mechanism having variable rigidity according to the present invention, the arm includes a pair of the guide portions, the elastic member includes a pair, and each of the elastic members can rotate independently about the rotation axis. It is preferable that the one end is configured to slide along each guide portion when rotating around the center. In this case, the rigidity of the rotating shaft and the position of the arm with respect to the support member can be adjusted by adjusting the rotation angle of each elastic member with respect to the support member.

The principle of the joint mechanism having variable rigidity according to the present invention in this case will be described with reference to FIG.
As shown in FIG. 1, when only one slider type pressurizing mechanism is used, when the actuator is subjected to a rotational displacement −φ by the actuator, the slider d pressurizes the arm a. Will only rotate. Therefore, in order to fix the arm a at a predetermined position, another slider type pressurizing mechanism is used as shown in FIG. These are called a slider type pressurizing mechanism I and a slider type pressurizing mechanism II. As shown in FIG. 2A, when the rotational displacement φ is applied to the slider pressure mechanism I and the rotational displacement −φ is applied to the slider pressure mechanism II, the arm a does not rotate. As shown in FIG. 2B, when it is desired to rotate the arm a about the rotation axis o by an angle θ, the rotational displacement θ−φ is applied to the slider type pressurizing mechanism I, and the rotational displacement is applied to the slider type pressurizing mechanism II. θ + φ can be given. Further, by adjusting the value of φ, the rigidity around the rotation axis o of the arm a can be changed.

  ADVANTAGE OF THE INVENTION According to this invention, the joint mechanism which has the variable rigidity which can be mounted in a robot arm, has high durability, and can suppress the influence by deterioration of an elastic member can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
3 to 8 show a joint mechanism having variable rigidity according to an embodiment of the present invention.
As shown in FIGS. 3 to 8, the joint mechanism 1 having variable rigidity is manufactured as an elbow joint of a robot arm, and includes an upper arm 2, a forearm model 3, a slider-type pressure mechanism 4, and an actuator 5. ing.

  As shown in FIGS. 3 and 4, the upper arm 2 has a bottom plate 21, a pair of side plates 22 and 23, an upper plate 24, and a joint plate 25. The bottom plate 21 is formed in a rectangular shape. The side plates 22 and 23 are provided on both side edges of the bottom plate 21 so as to rise perpendicularly to the bottom plate 21. The upper plate 24 is provided so as to connect the upper ends of the side plates 22 and 23 opposite to the forearms. The joint plate 25 is provided so as to connect the upper portions on the forearm side with respect to the upper plates 24 of the side plates 22 and 23. The joint plate 25 is attached to be inclined toward the bottom plate 21 on the forearm side so that when the arm is bent, the forearm is bent about 135 degrees with respect to the upper arm 2 in the same manner as a human being. The upper arm 2 forms a support member.

  As shown in FIGS. 3 and 4, the forearm model 3 includes a cylindrical model pipe 31, a forearm flange 32 attached to one end of the model pipe 31, and the forearm flange 32 opposite to the model pipe 31. And a flange fixing member 33 provided on the head.

  As shown in FIGS. 5 to 7, the slider pressure mechanism 4 includes a slider guide mechanism 41, a forearm transmission mechanism 42, and two pairs of slider mechanisms 43. As shown in FIG. 6, the slider guide mechanism 41 includes a joint shaft 41a, a pair of bearings 41b, a pair of large pulleys 41c, a pair of slider guides 41d, a pair of joint blocks 41e, and two pairs of spring guides 41f. And have. The joint shaft 41a is composed of an elongated shaft. The joint shaft 41a is provided with a collar (not shown) for attaching joint angle detection encoders at both ends.

  Each bearing 41b is cylindrical and has a joint shaft 41a inserted therein, and is provided at both ends of the joint shaft 41a. Each bearing 41b rotates smoothly around the joint shaft 41a. Each large pulley 41c is disk-shaped, and the joint shaft 41a passes through the center. Each large pulley 41c is arranged inside each bearing 41b, and can rotate independently around the joint shaft 41a. Each slider guide 41d includes an elongated rectangular plate-shaped side portion 41g and a pair of fixing portions 41h provided at both ends of the side portion 41g so as to extend perpendicularly to the same side with respect to the side portion 41g. Have. Each slider guide 41d has a joint shaft 41a passing through the center of the side portion 41g. Each slider guide 41d is arranged inside each large pulley 41c with each fixed portion 41h facing inward. Each slider guide 41d is fixed to each large pulley 41c by a hexagonal bolt, and rotates together with each large pulley 41c.

  Each joint block 41e has a rectangular parallelepiped shape and has an insertion hole (not shown) for inserting each spring guide 41f into a pair of facing surfaces. Each joint block 41e has a joint shaft 41a passing through the center of another pair of facing surfaces. Each joint block 41e is provided inside each slider guide 41d at a predetermined distance from each slider guide 41d. Each spring guide 41f has an elongated cylindrical shape and has a flange portion 41i at one end. The other end of each spring guide 41f is inserted into the insertion hole of each joint block 41e, and the flange portion 41i is fixed to each fixing portion 41h of each slider guide 41d. Each spring guide 41f is not fixed to each joint block 41e with a screw or the like so as to be displaceable with respect to the insertion hole of each joint block 41e. Each joint block 41e and each spring guide 41f rotate together with each slider guide 41d.

  Each joint block 41e is provided to prevent the upper and lower spring guides 41f from being cantilevered. Each joint block 41e plays a role as a post as if the upper and lower spring guides 41f are formed of a single shaft. Each joint block 41e is configured such that each spring guide 41f does not interfere with the joint shaft 41a because the joint shaft 41a passes therethrough.

  As shown in FIG. 6, the forearm transmission mechanism 42 includes a central transmission part 42 a and a pair of side transmission parts 42 b and 42 c. The central transmission part 42a has an elongated cubic shape. The central transmission part 42a has two pairs of central rail grooves 42d provided from the central part in the length direction to one end part along both side edges of the pair of side surfaces. Each side transmission part 42b, 42c comprises the rectangular frame shape. Each side transmission part 42b, 42c has the same side width as the width of the other pair of side faces of the central transmission part 42a. Each side transmission part 42b, 42c has one side surface fixed to the other pair of side surfaces, respectively. Each side transmission part 42b, 42c is being fixed to the position corresponding to each center rail groove | channel 42d of the center transmission part 42a so that the other end part of the length direction of the center transmission part 42a may protrude. Each of the side transmission portions 42b and 42c has a pair of side rail grooves 42e along the outer side edges of both end faces.

  The forearm transmission mechanism 42 is arranged inside each side transmission part 42b, 42c so that each joint block 41e is located. In the forearm transmission mechanism 42, the joint shaft 41a passes through the central transmission portion 42a and the side transmission portions 42b and 42c, and is rotatable independently of the joint blocks 41e and the spring guides 41f. As shown in FIGS. 3 and 4, in the forearm transmission mechanism 42, the flange fixing tool 33 of the forearm model 3 is fixed to the other end portion of the central transmission portion 42 a in the length direction. As a result, the forearm transmission mechanism 42 rotates together with the forearm model 3.

  As shown in FIG. 7, each slider mechanism 43 has a slider body 43a, a slider shaft 43b, a pair of slider sides 43c, a pair of rollers 43d, a pair of retaining rings 43e, and an elastic member 43f. . The slider main body 43a penetrates the inside in the horizontal direction and is attached with a slider shaft 43b. A bearing (not shown) for the slider shaft 43b is enclosed inside. The slider main body 43a has a spring installation surface 43g parallel to the slider shaft 43b and a guide through hole (not shown) provided so as to penetrate the center of the spring installation surface 43g. Each slider side 43c penetrates the slider shaft 43b, and is fixed to both side surfaces of the slider body 43a as a bearing stopper inside the slider body 43a.

  Each roller 43d has a cylindrical shape, and a slider shaft 43b passes through the center thereof. The rollers 43d are provided outside the slider side 43c so as to be rotatable about the slider shaft 43b as a rotation axis. Each roller 43d has a bearing (not shown) that is resistant to the compressive load applied by the elastic member 43f. Each retaining ring 43e has a disk shape, and a slider shaft 43b passes through the center. Each retaining ring 43e is attached to the outside of each roller 43d so as to prevent each roller 43d from being detached from the slider shaft 43b.

  The elastic member 43f is composed of a coil spring of a linear spring. The elastic member 43f is disposed on the spring installation surface 43g of the slider body 43a so that the inside communicates with the guide through hole. As shown in FIGS. 5 and 7, each slider mechanism 43 is attached to the slider guide mechanism 41 so that the spring guide 41f penetrates the inside of the elastic member 43f and the guide through hole. At this time, in each slider mechanism 43, each roller 43d is positioned in the central rail groove 42d and the side rail groove 42e, respectively, and can move linearly along each of the grooves 42d and 42e. Each slider mechanism 43 rotates together with each joint block 41e, each spring guide 41f, and the like.

  Thus, in the slider-type pressurizing mechanism 4, the slider guide 41 d transmits the torque of the rotational motion to the slider mechanism 43. The spring guide 41f assists the linear deformation of the elastic member 43f. When the spring guide 41f is not provided, the elastic member 43f is not deformed and compressed linearly, and the compressive force is biased to cause damage to the elastic member 43f. Therefore, the spring guide 41f must be attached.

  As shown in FIG. 3, the forearm model 3 and the slider-type pressurizing mechanism 4 are attached to the forearm side of the joint plate 25 of the upper arm 2 so that the model pipe 31 faces the forearm side. The slider type pressurizing mechanism 4 is provided between the side plates 22 and 23 of the upper arm 2 so that both ends of the joint shaft 41 a penetrate from the side plates 22 and 23. In the slider type pressurizing mechanism 4, each bearing 41b of the slider guide mechanism 41 is fixed to each side plate 22, 23 of the upper arm 2 as a rolling bearing, and the forearm transmission mechanism 42, the forearm model 3, each joint block 41e, each spring guide 41f. Are rotatable with respect to the upper arm 2 using the joint shaft 41a as a rotation axis.

  As shown in FIG. 4, the actuator 5 includes two units, and each includes a DC motor 51, a speed reducer 52, and a small pulley 53. The small pulley 53 is attached to the output shaft of the speed reducer 52. Each actuator 5 is disposed between the upper plate 24 and the bottom plate 21 of the upper arm 2 such that the small pulley 53 is in a position corresponding to each large pulley 41 c of the slider type pressurizing mechanism 4. Each actuator 5 is attached to an actuator mount 55 fixed to the upper plate 24 and the bottom plate 21 of the upper arm 2 by a fixing plate 54 so as to be parallel to each other in opposite directions.

  The actuator 5 transmits its power to the slider-type pressurizing mechanism 4 by a belt (not shown) wound around the small pulley 53 and the large pulley 41c. The pulley ratio between the large pulley 41 c and the small pulley 53 is 2: 1, and the torque from the actuator 5 is configured to be doubled by the slider type pressurizing mechanism 4. Further, as shown in FIG. 3, an idler 56 serving as a tension pulley is slidably attached to the side plates 22 and 23 of the upper arm 2 in order to prevent loss of power transmission by the belt. The idler 56 is configured to apply a tension that prevents the belt from slackening.

  As shown in FIG. 5, in the joint mechanism 1 having variable rigidity, the power from the actuator 5 gives a rotational motion to the slider guide mechanism 41. At this time, the slider mechanism 43 is inclined from the initial posture in the vertical state with respect to the forearm transmission mechanism 42 by the rotational force of the slider guide mechanism 41. As the inclination angle further increases, the spring length of the elastic member 43f of the slider mechanism 43 is compressed from the natural length. As a result, the force that the slider mechanism 43 acts on the forearm transmission mechanism 42 increases. That is, the force applied to the elastic member 43f increases with respect to the rotation angle of the slider guide mechanism 41, and as a result, the force acting on the forearm transmission mechanism 42 increases.

  In the joint mechanism 1 having variable rigidity, each slider mechanism 43 converts the rotational motion of the slider guide mechanism 41 into linear motion by each roller 43d, and transmits the compression load by the elastic member 43f from each roller 43d to the forearm transmission mechanism 42. I have a role to let you. The linear motion by each roller 43d is always steady as each roller 43d moves linearly along the central rail groove 42d and the side rail groove 42e. The forearm transmission mechanism 42 transmits a force received from the slider mechanism 43 through the central rail groove 42d and the side rail groove 42e, and as a result, is a rigid transmission unit that affects the forearm model 3 with the force.

  In the joint mechanism 1 having variable rigidity, the forearm transmission mechanism 42 and the forearm model 3 form an arm. The arm is provided on the upper arm 2 that is a support member so as to be rotatable about a rotation axis perpendicular to the length direction, that is, the joint axis 41a. The arm has a central rail groove 42d and a side rail groove 42e as guide portions along the length direction. The guide portion is provided at a predetermined distance from the joint shaft 41a in a direction perpendicular to the length direction of the model pipe 31.

  The elastic member 43f is provided on the upper arm 2 so as to be rotatable about the joint shaft 41a so that the compression direction always faces the joint shaft 41a. When the elastic member 43f rotates around the joint shaft 41a, one end on the joint shaft 41a side is slid along the central rail groove 42d and the side rail groove 42e by each roller 43d, and the other is formed by the flange portion 41i of the spring guide 41f. The distance between the end and the joint shaft 41a is held constant. As a result, the elastic member 43f allows the forearm transmission mechanism 42 to exert an urging force directed toward the joint shaft 41a, and can change the angle between the direction of the urging force and the model pipe 31. Further, the magnitude of the urging force changes according to the direction of the urging force and the angle formed by the model pipe 31, and the rigidity of the joint shaft 41a changes non-linearly.

Next, the operation will be described.
Since the joint mechanism 1 having variable rigidity has a relatively simple configuration, the weight and size can be reduced, and the joint mechanism 1 can be mounted as a joint mechanism 1 of a robot arm subject to restrictions on the weight and size. . The magnitude of the urging force acting on the forearm transmission mechanism 42 changes in accordance with the direction of the urging force toward the joint shaft 41a by the elastic member 43f and the angle formed with the model pipe 31, and the stiffness of the joint shaft 41a becomes nonlinear. Therefore, the joint shaft 41a, that is, the joint rigidity can be changed from high rigidity to low rigidity.

  In the case of a non-linear elastic member such as rubber, the output with respect to the input becomes non-linear, so that the output greatly changes with a slight input error or characteristic change. On the other hand, in the joint mechanism 1 having variable rigidity, since the elastic member 43f has linearity, the output changes linearly with respect to the input error or characteristic change, and the error can be easily estimated. Further, since the direction in which the urging force of the elastic member 43f acts on the forearm transmission mechanism 42 changes, the joint shaft 41a, that is, the stiffness of the joint is changed, so that the influence of the deterioration of the elastic member 43f can be suppressed, and It is easy to estimate the impact. Since the elastic member 43f is made of a coil spring, the durability is high.

  The joint mechanism 1 having variable rigidity adjusts the rotation angle of each elastic member 43 f with respect to the upper arm 2 by the actuator 5, thereby providing two outputs of the rigidity of the joint shaft 41 a and the position (joint angle) of the model pipe 31 with respect to the upper arm 2. Can be adjusted. That is, the joint mechanism 1 having variable rigidity can perform the following three behaviors by operating the two actuators 5.

  Low rigidity state: When two opposing slider guides 41d are in the same phase (same rotation direction and same rotation angle), the angle of the joint shaft 41a is changed, that is, the forearm is moved, and the joint rigidity is low. .

  High rigidity state: Contrary to the low rigidity state, the joint shaft 41a does not change in the opposite phase state (the rotation directions are opposite and the same rotation angle), but as the rotation angle of the slider guide 41d increases. Further, the support force of the slider mechanism 43 with respect to the forearm transmission mechanism 42 increases. Further, as the difference in the reverse phase (the difference in absolute value of the rotation angle) occurs, the urging force to the forearm transmission mechanism 42 increases and the joint rigidity changes to high rigidity. FIG. 8 shows the situation at this time. However, in this state, only the stiffness is changed, and the joint angle cannot be changed.

  A state in which the stiffness and the joint angle are changed: When the low stiffness state and the high stiffness state are combined, that is, when the forearm (model pipe 31) is moved while changing the joint angle while having a certain degree of stiffness, This can be realized if there is a difference in the rotation angle of the slider guide 41d. As an example, in order to bend the forearm by 90 degrees from the horizontal state (joint angle is 0 degree) and also change the rigidity, the rotation angle of each slider guide 41d is set to 105 degrees and 75 degrees in the same direction. To do. At this time, the forearm (model pipe 31) can be bent 90 degrees with respect to the upper arm 2. Furthermore, since the angle difference of each slider guide 41d is 30 degrees, this angle difference appears as joint rigidity. Similarly, if each slider guide 41d has an angle of 120 degrees and 60 degrees in the same rotational direction, the forearm bends 90 degrees and the angle difference is 60 degrees, so that the rigidity is higher than the previous 30 degrees. .

  The joint mechanism 1 having variable rigidity is expected to be applied not only to robot joints but also to medical aids such as artificial legs and artificial arms. For the user side of the medical aid, a joint having flexibility is close to a human joint and thus has an affinity, and an improvement in convenience in real life can be expected.

It is a principle figure which shows the principle of the joint mechanism which has variable rigidity based on this invention. It is a principle figure which shows the principle when two slider type pressurization mechanisms of the joint mechanism which has the variable rigidity based on this invention are used. It is a perspective view which shows the joint mechanism which has the variable rigidity of embodiment of this invention. It is the perspective view which removed one side board and upper board of the exterior of the joint mechanism which has variable rigidity shown in FIG. It is a perspective view which shows the slider type pressurization mechanism of the joint mechanism which has the variable rigidity shown in FIG. FIG. 4 is a perspective view showing a slider guide mechanism and a forearm transmission mechanism of the joint mechanism having variable rigidity shown in FIG. 3. It is a perspective view which shows the slider mechanism of the joint mechanism which has the variable rigidity shown in FIG. It is a side view which shows the slider type pressurization mechanism of the highly rigid state of the joint mechanism which has the variable rigidity shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joint mechanism with variable rigidity 2 Upper arm 21 Bottom plate 22, 23 Side plate 24 Upper plate 25 Joint plate 3 Forearm model 31 Model pipe 32 Forearm flange 33 Flange fixture 4 Slider type pressurization mechanism 41 Slider guide mechanism 41a Joint shaft 41b Bearing 41c Large pulley 41d Slider guide 41e Joint block 41f Spring guide 42 Forearm transmission mechanism 42a Central transmission part 42b, 42c Side transmission part 42d Central rail groove 42e Side rail groove 43 Slider mechanism 43a Slider body 43b Slider shaft 43c Slider side 43d Roller 43e Stop Wheel 43f Elastic member 5 Actuator 51 DC motor 52 Reduction gear 53 Small pulley 54 Fixed plate 55 Actuator mount 56 Idler

Claims (3)

A support member, an arm, and an elastic member;
The arm is provided on the support member so as to be rotatable about a rotation axis perpendicular to the length direction,
The elastic member has linearity, and is provided on the support member so that an urging force directed to the rotation shaft is applied to the arm, and an angle formed by the direction of the urging force and the arm is changeable. In accordance with the direction of the force and the angle formed by the arm, the magnitude of the biasing force is changed, and the rigidity of the rotating shaft is configured to change nonlinearly.
A joint mechanism having variable rigidity. The arm has a guide portion along a length direction, and the guide portion is provided at a predetermined distance from the rotation axis in a direction perpendicular to the length direction of the arm,
The elastic member is formed of a compression spring, and is provided on the support member so as to be rotatable about the rotation axis so that the compression direction is always directed to the rotation axis, and when rotating about the rotation axis, One end slides along the guide portion, and the distance between the other end and the rotation shaft is held constant.
The joint mechanism having variable rigidity according to claim 1. The arm has a pair of the guide portions,
The elastic member is formed of a pair, and can be independently rotated about the rotation axis, and is configured such that, when rotating about the rotation axis, the one end slides along each guide portion. That
The joint mechanism having variable rigidity according to claim 2.

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