Link-coupled adaptive underactuated robot finger device

Abstract

The connecting rod coupling adaptive underactuated robot finger device belongs to the field of robot hand technology, and includes a motor, a transmission mechanism, a base, a first finger segment, a second finger segment, a proximal joint axis, a distal joint axis, a first connecting rod, a second connecting rod, a first rotating shaft, a second rotating shaft, a third rotating shaft, a spring, and a limit convex block. The device has the functions of coupled grasping and adaptive grasping, and can realize the grasping function of a robot finger with two degrees of freedom driven by a single motor. In the initial stage, the coupling linkage method is used to realize the simultaneous movement of two joints, which is convenient for the end-point pinching grasping. For larger objects, two finger segments can also be used to contact to achieve the effect of implementing envelope grasping; it can automatically adapt to objects of different shapes and sizes, without the need for real-time sensing and complex control of the environment and objects, and at the same time, it has a simple structure and low cost, and is suitable for anthropomorphic robots.

Description

Technical Field

[0001] The present invention belongs to the technical field of robotic hands, and particularly relates to the structural design of a link-coupled adaptive under-actuated robotic finger device. Background Art

[0002] The technology and application of robots have developed rapidly in China. The application of industrial robots in industry and manufacturing has promoted the formation of intelligent factories and unmanned factories, greatly improving social productivity. Correspondingly, intelligent humanoid robots have also become the forefront of the academic field in recent years. Many scientists have proposed innovations to existing robots from different angles and fields to make robots more human-like. Coupled with the emergence of AI technology, the intelligent level of robots has been significantly improved, and robots are slowly becoming more like real people.

[0003] The robotic hand is an important part of the robot, performing the end grasping and operating tasks of the robot. People are keen on imitating the human hand. Existing highly realistic robotic hands have a high similarity in appearance to the human hand, with a large number of joint degrees of freedom, and are actively driven by multiple motors. They can complete various grasping and gesture actions similar to those of the human hand. However, the high integration results in a complex structure, requiring complex sensing and real-time control systems. The drive control system is bulky, the grasping force is small, and the design, manufacturing, and maintenance costs are high, making it difficult to promote and apply.

[0004] The human hand has two main characteristics in grasping:

[0005] 1) Coupled pinching: For small objects, it is necessary to bend multiple joints of the fingers and pinch the object with the opposite finger tips.

[0006] 2) Enveloping grasping: For large objects, it is necessary to use multiple finger segments to envelope the object contour and grasp the object in a holding manner, increasing the contact points and providing a larger grasping force to achieve a force-based stable grasping.

[0007] Traditional adaptive under-actuated fingers can adopt the enveloping grasping method to adaptively grasp objects, driving multiple joint degrees of freedom with a small number of motors, without the need for sensing and complex control systems, reducing the control difficulty and cost, and being suitable for popularization and use. However, traditional adaptive under-actuated fingers cannot perform coupled pinching grasping. Several finger segments need to rotate and contact the target in sequence, and the grasping time is relatively long. For example, an existing under-actuated two-joint robotic finger device (a Chinese invention patent with the publication number CN101234489A) includes a base, a motor, a middle finger segment, a terminal finger segment, a belt drive mechanism, etc. This device realizes the special effect of a double-joint under-actuated finger bending to grasp an object and has self-adaptability. Its disadvantage is that the finger always presents a straight state before touching the object and uses the holding grasping method, making it difficult to achieve the anthropomorphic grasping effect of coupled pinching.

[0008] An underactuated finger with two grasping modes, namely coupled pinch and adaptive envelope grasping (coupled adaptive), has been developed. An existing coupled adaptive clamping device (a Chinese invention patent with the publication number CN106142117A) includes a parallelogram linkage mechanism, multiple pulleys, two finger segments, a spring member, and mechanical constraints, etc. This device realizes the coupled adaptive grasping mode, but its disadvantages are that the device has a complex mechanism, a large volume, uses flexible components, has inaccurate transmission, and the rope will become loose after long-term use, which further affects the transmission accuracy. Summary of the Invention

[0009] To overcome the deficiencies of the existing technology, the purpose of the present invention is to provide a linkage-coupled adaptive underactuated robot finger device. This device can realize the grasping function of a robot finger with two degrees of freedom of joints driven by a single motor. In the initial stage, it realizes the simultaneous movement of the two joints in a coupled linkage manner, which is convenient for pinch grasping at the end. For larger objects, it can also use the two finger segments to contact to achieve the effect of envelope grasping; it can automatically adapt to objects of different shapes and sizes without real-time sensing and complex control of the environment and objects. At the same time, it has a simple structure and low cost, and is suitable for anthropomorphic robots.

[0010] The purpose of the present invention is achieved by adopting the following technical solutions. A linkage-coupled adaptive underactuated robot finger device according to the present invention includes a motor, a transmission mechanism, a base, a first finger segment, a second finger segment, a proximal joint axis, and a distal joint axis; the motor is fixedly connected to the base, and the output shaft of the motor is connected to the input end of the transmission mechanism; the proximal joint axis is movably sleeved in the base, and the first finger segment is movably sleeved on the proximal joint axis; the distal joint axis is movably sleeved in the first finger segment, and the second finger segment is movably sleeved on the distal joint axis; the center line of the proximal joint axis is parallel to the center line of the distal joint axis; this linkage-coupled adaptive underactuated robot finger device further includes a first link, a second link, a first rotating shaft, a second rotating shaft, a third rotating shaft, a spring member, and a limit convex block; the first rotating shaft is movably sleeved in the base; the output end of the transmission mechanism is connected to the first link; one end of the first link is sleeved on the first rotating shaft, and the other end is sleeved on the second rotating shaft; the third rotating shaft is fixedly connected to the second finger segment; one end of the second link is sleeved on the second rotating shaft, and the other end is sleeved on the third rotating shaft; the two ends of the spring member are respectively connected to the first link and the second link; the limit convex block is fixedly connected to the first link, and in the initial state, under the action of the spring member, the second link abuts against the limit convex block;

[0011] The near joint axis, far joint axis, first rotating shaft, second rotating shaft, and third rotating shaft satisfy the following relationships: Let the center point of the near joint axis be A, the center point of the first rotating shaft be B, the center point of the far joint axis be C, the center point of the third rotating shaft be D, and the center point of the second rotating shaft be E; The line segment AC intersects with the line segment BD, and the line segments AB, BD, DC, and CA form an "8"-shaped quadrilateral. The points B, D, and E are connected to form a triangle, and the points E and C are on both sides of the line segment BD respectively.

[0012] Further, the transmission mechanism includes a reducer, a first pulley, a transmission belt, and a second pulley; The output shaft of the motor is connected to the input shaft of the reducer; The first pulley is fixedly sleeved on the output shaft of the reducer; The transmission belt is respectively connected to the first pulley and the second pulley; The first pulley, the second pulley, and the transmission belt cooperate to form a pulley transmission relationship; The second pulley is sleeved on the first rotating shaft; The second pulley is fixedly connected to the first connecting rod.

[0013] Further, the spring member is a tension spring or a torsion spring.

[0014] The device of the present invention has the following beneficial effects and prominent features:

[0015] The present invention uses a motor, two connecting rods, a spring member, and a limit convex block to comprehensively realize a connecting rod coupling adaptive underactuated robot finger device. This device can realize the grasping function of a robot finger with two joint degrees of freedom driven by a single motor. In the initial stage, it uses a coupling linkage method to realize the simultaneous movement of the two joints, which is convenient for the end to pinch and grasp. For larger objects, the two finger segments can also be used to contact, achieving the effect of envelope grasping; It can automatically adapt to objects of different shapes and sizes, without the need for real-time sensing and complex control of the environment and objects. At the same time, the structure is simple, the cost is low, and it is suitable for anthropomorphic robots.

[0016] The above description is only an overview of the technical solution of the present invention. In order to be able to more clearly understand the technical means of the present invention, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given, and in conjunction with the drawings, the details are described as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a three-dimensional external view of an embodiment of the connecting rod coupling adaptive underactuated robot finger device designed by the present invention.

[0018] Figure 2 is Figure 1 a three-dimensional external view of the shown embodiment in another direction (removing some parts).

[0019] Figure 3 is Figure 1Front view of the illustrated embodiment.

[0020] Figure 4 is Figure 1 Right view of the illustrated embodiment (with some parts removed).

[0021] Figure 5 is Figure 1 Cross-sectional view of the illustrated embodiment.

[0022] Figure 6 is Figure 1 Position diagram of some parts in the illustrated embodiment.

[0023] Figure 7 is Figure 1 Position diagram of some parts in the illustrated embodiment.

[0024] Figures 8 to 11 is Figure 1 Schematic diagram of the action process of grasping an object in the illustrated embodiment in the manner of coupling adaptive envelope grasping.

[0025] Figure 12 is Figure 1 Superposition diagram of the pose states at different moments during the movement process of the illustrated embodiment.

[0026] Figures 13 to 15 is Figure 1 Schematic diagram of the action process of coupling and clamping a small object in the illustrated embodiment.

[0027] Figure 16 , Figure 17 , Figure 18 is Figure 1 Change situation of the relative positions of the spring member, the first link and the second link at several key positions during the action process of grasping an object in the manner of coupling adaptive envelope grasping in the illustrated embodiment.

[0028]

Reference Signs

[0029] 1 - Base, 2 - First finger segment, 3 - Second finger segment, 4 - Proximal joint axis, 5 - Distal joint axis, 61 - First link, 62 - Second link, 71 - First rotating shaft, 72 - Second rotating shaft, 73 - Third rotating shaft, 8 - Spring member, 90 - Object, 9 - Limit projection, 14 - Motor, 141 - Reducer, 145 - First pulley, 146 - Transmission belt, 147 - Second pulley. Detailed implementation manners

[0030] The following further details the specific structure and working principle of the present invention in conjunction with the drawings and embodiments.

[0031] An embodiment of a link-coupled adaptive underactuated robot finger device according to the present invention, as Figures 1 to 7As shown in the figure. This embodiment includes a motor 14, a transmission mechanism, a base 1, a first finger segment 2, a second finger segment 3, a proximal joint axis 4, and a distal joint axis 5; the motor 14 is fixedly connected to the base 1, and the output shaft of the motor 14 is connected to the input end of the transmission mechanism; the proximal joint axis 4 is movably sleeved in the base 1; the first finger segment 2 is movably sleeved on the proximal joint axis 4; the distal joint axis 5 is movably sleeved in the first finger segment 2; the second finger segment 3 is movably sleeved on the distal joint axis 5; the center line of the proximal joint axis is parallel to the center line of the distal joint axis. This embodiment further includes a first connecting rod 61, a second connecting rod 62, a first rotating shaft 71, a second rotating shaft 72, a third rotating shaft 73, a spring member 8, and a limiting convex block 9; the first rotating shaft 71 is movably sleeved in the base; the output end of the transmission mechanism is connected to the first connecting rod 61; one end of the first connecting rod 61 is movably sleeved on the first rotating shaft 71, and the other end of the first connecting rod 61 is movably sleeved on the second rotating shaft 72; the third rotating shaft 73 is fixedly connected to the second finger segment 3, and the center lines of the first rotating shaft, the second rotating shaft, and the third rotating shaft are arranged in parallel; one end of the second connecting rod 62 is movably sleeved on the second rotating shaft 72, and the other end of the second connecting rod 62 is movably sleeved on the third rotating shaft 73; the two ends of the spring member 8 are respectively connected to the first connecting rod 61 and the second connecting rod 62; the limiting convex block 9 is fixedly connected to the first connecting rod 61; in the initial state, under the action of the spring member 8, the second connecting rod 62 abuts against the limiting convex block 9; Please refer to Figure 5 , let the center point of the proximal joint axis 4 be A, the center point of the first rotating shaft 71 be B, the center point of the distal joint axis 5 be C, the center point of the third rotating shaft 73 be D, and the center point of the second rotating shaft 72 be E; the line segment AC intersects the line segment BD, and the line segments AB, BD, DC, and CA form an "8"-shaped quadrilateral, and the three points B, D, and E are connected to form a triangle, and the points E and C are respectively on both sides of the line segment BD.

[0032] In this embodiment, the transmission mechanism includes a reducer 141, a first pulley 145, a transmission belt 146, and a second pulley 147; the output shaft of the motor 14 is connected to the input shaft of the reducer 141; the first pulley 145 is fixedly sleeved on the output shaft of the reducer 141; the transmission belt 146 is respectively connected to the first pulley 145 and the second pulley 147; the first pulley 145, the second pulley 147, and the transmission belt 146 cooperate to form a pulley transmission relationship; the second pulley 147 is sleeved on the first rotating shaft 71; the second pulley 147 is fixedly connected to the first connecting rod 61.

[0033] In this embodiment, the spring member 8 is a tension spring. Of course, in other embodiments, a torsion spring can also be used.

[0034] The working principle of this embodiment is described as follows in combination with the accompanying drawings:

[0035] The motor 14 rotates. Driven by the speed reducer, the first pulley, and the second pulley, the first link 61 rotates clockwise (as Figures 8 to 15 shown) and approaches the object 90. The rotation of the first link 61 will cause the linkage of the second link 62, the first finger segment 2, and the second finger segment 3. Let the angle between the first link and the horizontal line be α, and the angle between the first link 61 and the second link 62 be β. In this linkage situation, since the spring member 8 makes the limit bump 9 contact the second link 62 in the initial state, the triangle formed by triangle BDE does not deform, which will cause the second finger segment 3 to also rotate simultaneously around the distal joint axis 5. At this time, α decreases and β remains unchanged (as Figures 16 to 17 shown), achieving the function of the coupled rotation of the first finger segment 2 and the second finger segment 3. This process has a high degree of anthropomorphism.

[0036] If the second finger segment 3 touches the object 90 at this time, the clamping ends, achieving the effect of coupled grasping. This grasping mode is suitable for pinching small objects with the end of the second finger segment 3 (as Figures 13 to 15 shown).

[0037] If in the above process, the first finger segment 2 touches the object 90 first, then the first finger segment 2 is blocked by the object 90 and cannot move. At this time, the motor 14 continues to rotate, driving the first link 61 to continue rotating through the transmission mechanism (as Figure 8 to 11 shown). In the case where the first finger segment 2 is restricted from rotating, the spring member 8 will be stretched and deformed, and the limit bump 9 and the second link 62 will separate. The second finger segment 3 will have a further rotation around the distal joint axis 5. This rotation is based on the fact that triangle BDE deforms and the angle BED becomes larger, that is, Figure 18 the angle β of Figure 17 is larger than the angle β of

[0038] This realizes the further bending of the second finger segment 3 until it touches the object 90. In this way, it can adapt to different object shapes and sizes, achieving the effect of adaptive envelope grasping.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the design and scope of the technical solutions of the present invention.

Claims

1. A link-coupled adaptive underactuated robot finger device, comprising a motor, a transmission mechanism, a base, a first finger segment, a second finger segment, a proximal joint axis and a distal joint axis; the motor is fixedly connected to the base, and the output shaft of the motor is connected to the input end of the transmission mechanism; the proximal joint axis is movably sleeved in the base, and the first finger segment is movably sleeved on the proximal joint axis; the distal joint axis is movably sleeved in the first finger segment, and the second finger segment is movably sleeved on the distal joint axis; the centerline of the proximal joint axis is parallel to the centerline of the distal joint axis; it is characterized in that: The link-coupled adaptive underactuated robot finger device also includes a first link, a second link, a first rotating shaft, a second rotating shaft, a third rotating shaft, a spring member, and a limiting protrusion; the first rotating shaft is movably sleeved in the base; the output end of the transmission mechanism is connected to the first link; one end of the first link is sleeved on the first rotating shaft, and the other end is sleeved on the second rotating shaft; the third rotating shaft is fixedly connected to the second finger segment; one end of the second link is sleeved on the second rotating shaft, and the other end is sleeved on the third rotating shaft; the two ends of the spring member are respectively connected to the first link and the second link; the limiting protrusion is fixedly connected to the first link, and in the initial state, under the action of the spring member, the second link is close to the limiting protrusion; The proximal joint axis, distal joint axis, first rotation axis, second rotation axis and third rotation axis conform to the following relationship: let the center point of the proximal joint axis be A, the center point of the first rotation axis be B, the center point of the distal joint axis be C, the center point of the third rotation axis be D, and the center point of the second rotation axis be E; line segment AC intersects with line segment BD, line segment AB, line segment BD, line segment DC and line segment CA form an "8"-shaped quadrilateral, and the lines connecting points B, D and E form a triangle, and point E and point C are respectively on both sides of line segment BD.

2. A link-coupled adaptive underactuated robot finger device according to claim 1, characterized in that: The transmission mechanism includes a reducer, a first pulley, a transmission belt and a second pulley; the output shaft of the motor is connected to the input shaft of the reducer; the first pulley is fixed on the output shaft of the reducer; the transmission belt connects the first pulley and the second pulley respectively; the first pulley, the second pulley and the transmission belt cooperate to form a pulley transmission relationship; the second pulley is sleeved on the first rotating shaft; the second pulley is fixed to the first connecting rod.

3. The link-coupled adaptive underactuated robot finger device according to claim 1, characterized in that: The spring element is a tension spring or a torsion spring.

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