A continuum robot capable of stiffness self-regulation

Abstract

The application relates to the field of continuum robots, and particularly relates to a continuum robot capable of realizing self-adjusting rigidity, which comprises a continuum robot body, a plurality of traction ropes, a plurality of supporting discs, a plurality of tensioning reels and a plurality of limiting springs. The continuum robot body comprises an operating arm, a front end base, a rear end base and a driving mechanism. The operating arm comprises a plurality of flexible rods arranged axially in parallel. The first ends of the flexible rods are fixed on the front end base. The driving mechanism is fixed on the rear end base. The ends of the flexible rods can independently move axially in the rear end base. The tensioning reels are fixed on the front end base. The application makes the operating arm have variable warping in the axial direction, thereby improving the self-adaptive rigidity gain of the operating arm. The rigidity gain component has a simple structure. Since the rigidity gain component is installed in the operating arm, the rigidity gain component does not occupy the external space of the operating arm, has high volume utilization rate, and the overall structure does not have a prime mover.

Description

Technical Field

[0001] This invention relates to the field of continuum robots, and more specifically to a continuum robot capable of self-adjusting stiffness. Background Technology

[0002] In recent years, continuum robots have developed rapidly. Unlike traditional rigid robots, they possess the unique characteristic of controllable deformation, enabling continuous deformation (the main curve has continuous tangent vectors) and infinite degrees of freedom. This makes them more adaptable to complex working conditions and application requirements, thus their application and promotion have gradually become a new hot topic and area of ​​exploration. However, while continuum robots have controllable deformation capabilities, their materials also limit the amount of rigid support they can provide during application. This makes it difficult to balance the load capacity and operational space accuracy of the soft manipulator. When the soft manipulator is carrying a large object, its bending deflection becomes significant, resulting in a large deviation of the manipulator's end-effector position, which greatly affects operational space accuracy. It also makes it difficult to balance the manipulator's operational elongation and operational space accuracy. When the operational elongation of the soft manipulator is too long, the deviation of the manipulator's end-effector position also becomes large, significantly impacting operational space accuracy. Therefore, achieving variable stiffness in continuum robots is an urgent need.

[0003] Currently, continuum robots are still mainly driven by air and liquid, and methods to change stiffness are also concentrated in this field. For example, Chinese patent CN112692872B discloses a pneumatically based continuously variable stiffness spinal joint, which is based on the design of a pneumatic structure of joint units of continuum. Variable stiffness is achieved by adjusting the air source pressure, but it cannot meet the requirement of the mechanism to achieve adaptive stiffness gain based on characteristics such as bending deflection.

[0004] Chinese patent application CN114227696A discloses a biomimetic rigid-flexible coupled variable stiffness continuum robot and its control method. The proposed biomimetic rigid-flexible coupled variable stiffness continuum robot has the characteristic of variable stiffness by adding relevant structures to the outside of the continuum robot. However, the structure must be attached to the outside of the continuum robot and the arrangement density is high, which greatly increases the size and mechanical complexity of the continuum robot. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the fact that although the continuum robot in the prior art has the characteristic of variable stiffness, it is necessary to add rigid gain components to the outside of the continuum robot, and the arrangement density is high, which greatly increases the size and structural complexity of the continuum robot and reduces the working reliability of the continuum robot.

[0006] To address the aforementioned technical problems, this invention provides a continuous robot capable of self-adjusting stiffness, comprising a continuous robot body, several traction ropes, several support discs, several tension reels, and several limiting springs. The continuous robot body includes an operating arm, a front base, a rear base, and a drive mechanism. The operating arm includes several axially parallel flexible rods, the ends of which are fixed to the front base. The drive mechanism is fixed to the rear base, and the end of each flexible rod can move independently axially within the rear base under the drive mechanism. The tension reels are all fixed to the front base. One end of each traction rope is fixed to the inner side of the rear base, and the other end is wound around the tension reel. The support discs include two adjacent first radial branch segments, a second radial branch segment, and a third radial branch segment. Two radial branch segments and a third radial branch segment, the number of branch segments, the number of flexible rods and the number of traction ropes are corresponding. Several support discs are distributed at intervals along the axial direction of the operating arm, and each branch segment is respectively sleeved on a flexible rod. The limiting spring is sleeved on the flexible rod, so that the support discs remain evenly spaced when the continuous robot body is working dynamically. The traction ropes also pass through the corresponding branch segments in sequence. When the continuous robot is working dynamically, the traction rope on one branch segment of each support disc applies a force to the outside of the continuous robot body, and the traction rope on the other branch segments applies a force to the inside of the continuous robot body. The position of the branch segment with the traction rope that applies a force to the outside of the continuous robot body extends clockwise or counterclockwise along the axial direction of the operating arm.

[0007] Furthermore, each branch segment of the support plate is provided with a through hole at its outer end.

[0008] Furthermore, each branch segment of the support plate is provided with an installation port in the middle, and a pulley is rotatably connected inside the installation port. The rotation axis of the pulley is perpendicular to the radial direction of the branch segment. The traction rope on one branch segment of each support plate is threaded between the inner end of the installation port and the pulley, and the traction rope on the other branch segment is threaded between the outer end of the installation port and the pulley. The position of the branch segment with the traction rope threaded between the inner end of the installation port and the pulley extends clockwise or counterclockwise along the axial direction of the operating arm.

[0009] Furthermore, the front-end base includes several fixed terminals and a connecting plate I. The number of side lengths of the connecting plate I and the number of fixed terminals correspond to the number of flexible rods. Each included angle of the connecting plate I is fixed with a fixed terminal, and the head end of each flexible rod is fixed in the corresponding fixed terminal.

[0010] Furthermore, the rear base includes several drive terminals and a connecting plate II. The number of side lengths of the connecting plate II and the number of drive terminals correspond to the number of flexible rods. Each included angle of the connecting plate II is fixed with a drive terminal, and the end of each flexible rod passes through the corresponding drive terminal.

[0011] Furthermore, the driving mechanism includes a first driving mechanism, a second driving mechanism, and a third driving mechanism that are independently configured, and the first driving mechanism, the second driving mechanism, and the third driving mechanism are respectively fixed on three driving terminals.

[0012] The technical solution of this invention has the following advantages:

[0013] This invention provides a continuous robot with self-adjusting stiffness. Through a special traction arrangement and support structure, the manipulator arm exhibits axial warping of three flexible rods, thereby improving its stiffness. Furthermore, it avoids the impact on the accuracy of the operating space caused by the previously low stiffness of the manipulator arm under heavy loads or large extensions. The rigidity gain component of this invention has a simple structure; because it is installed inside the manipulator arm, it does not occupy external space, resulting in high volume utilization. The overall structure has no prime mover, requires no external control, and has high reliability. This gain component uses linearly varying rope tension, acting on the continuous robot through a support plate, effectively fitting the stiffness variation requirements of the continuous robot under both elongation and bending conditions, without affecting the robot's main performance indicators. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is an overall schematic diagram of a continuum robot capable of self-adjusting stiffness provided in an embodiment of the present invention;

[0016] Figure 2 A perspective view of the rear base provided for an embodiment of the present invention;

[0017] Figure 3 A perspective view of the front-end base provided for an embodiment of the present invention;

[0018] Figure 4 A perspective view of the support disk provided for an embodiment of the present invention;

[0019] Figure 5 A structural diagram of the driving mechanism provided for an embodiment of the present invention;

[0020] Figure 6 A cross-sectional view of the flexible rod inside the drive terminal and its corresponding drive structure provided for an embodiment of the present invention;

[0021] Figure 7 An external view of the traction rope fixing part provided for an embodiment of the present invention;

[0022] Figure 8 A cross-sectional view of the traction rope fixing part provided in an embodiment of the present invention;

[0023] Figure 9 This is a schematic diagram illustrating the misalignment of the support disk in an embodiment of the present invention;

[0024] Figure 10 This is a schematic diagram of the force applied to the support plate according to an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached drawings: 1. Continuous robot body; 11. Manipulator arm; 111. Flexible rod; 12. Front base; 121. Fixed terminal; 122. Connecting plate I; 13. Rear base; 131. Drive terminal; 132. Connecting plate II; 14. Drive mechanism; 141. First drive mechanism; 142. Second drive mechanism; 143. Third drive mechanism; 01. DC motor; 02. Reducer; 03. Drive gear ; 04. Driven gear; 05. First sliding pin; 06. Second sliding pin; 07. Third sliding pin; 131a. Front hollow cylinder; 131b. Rear hollow cylinder; 131c. Connecting rib; 2. Traction rope; 3. Support plate; 31. Through hole; 32. Mounting port; 33. Pulley; 4. Tensioning reel; 5. Limiting spring; 6. Traction rope fixing part; 61. Outer tube; 62. Fixing rod; 63. Locking screw; 64. Threaded hole. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The present invention provides a continuous robot with self-adjustable stiffness, comprising a continuous robot body 1, a plurality of traction ropes 2, a plurality of support discs 3, a plurality of tensioning reels 4 and a plurality of limiting springs 5. The continuous robot body 1 includes an operating arm 11, a front base 12, a rear base 13 and a drive mechanism 14.

[0031] The operating arm 11 provided in this embodiment of the invention includes three axially parallel flexible rods 111. The surface of the flexible rods 111 is provided with threads. The head end of each flexible rod 111 is fixed on the front end base 12. The driving mechanism 14 is fixed on the rear end base 13. The end of each flexible rod 111 can move axially independently within the rear end base 13 under the drive of the driving mechanism 14. When the three flexible rods 111 move towards the front end with the same increment, the operating arm 11 moves forward as a whole (or extends). When the three flexible rods 111 move towards the front end with different increments, the operating arm 11 bends.

[0032] The tensioning reels 4 are all fixed to the front base 12. One end of the traction rope 2 is fixed to the inner side of the rear base 13, and the other end is wound on the tensioning reel 4. The rear base 13 is provided with a traction rope fixing part, which corresponds to the number of traction ropes 2. The traction rope fixing part includes an outer tube 61, a fixing rod 62, and a locking screw 63. The end of the traction rope is fixed to the fixing rod 62. When it is necessary to install the traction rope 2, the fixing rod 62 can be coaxially inserted into the outer tube 61. The outer tube 61 has a threaded hole 64 on its circumferential surface. The locking screw 63 is threadedly connected to the threaded hole 64. When the locking screw 63 is screwed to the innermost position, so that the tail end of the locking screw 63 tightly abuts against the fixing rod 62, one end of the traction rope 2 is fixed to the rear base 13.

[0033] In this embodiment of the invention, the number of branch segments and traction ropes 2 is also 3, which must correspond to the number of flexible rods 111.

[0034] The support plate 3 includes a first radial branch segment, a second radial branch segment, and a third radial branch segment that are adjacent to each other.

[0035] Several support discs 3 are distributed at intervals along the axial direction of the operating arm 11, and each branch segment is respectively sleeved on a flexible rod 111. The outer ends of the first radial branch segment, the second radial branch segment and the third radial branch segment are provided with a through hole 31, and the three through holes 31 allow the three flexible rods 111 to pass through.

[0036] The limiting spring 5 is a lightweight spring that is sleeved on the flexible rod 111 to separate the rear base 13 from the adjacent support plate 3, separate two adjacent support plates 3, and separate the front base 12 from the adjacent support plate 3, so that the support plates 3 are evenly distributed on the operating arm 11. The support plates 3 maintain an evenly distributed distribution when the continuous robot body 1 is working dynamically.

[0037] The traction rope 2 also passes through the corresponding branch segments in sequence. When the continuous robot is working dynamically, each branch segment of the support plate 3 is provided with an installation port 32 in the middle. A pulley 33 is rotatably connected in the installation port 32. The rotation axis of the pulley 33 is perpendicular to the radial direction of the branch segment. The traction rope 2 on one branch segment of each support plate 3 passes between the inner end of the installation port 32 and the pulley 33. The traction rope 2 on the other branch segment passes between the outer end of the installation port 32 and the pulley 33. The position of the branch segment with the traction rope 2 passing between the inner end of the installation port 32 and the pulley 33 extends clockwise or counterclockwise along the axial direction of the operating arm 11.

[0038] The support discs 3 distributed along the axial direction of the operating arm 11 provided in this embodiment of the invention are Z1, Z2, and Z3 from end to beginning. The first radial segment of Z1 is d11, the second radial segment is d12, and the third radial segment is d13. The first radial segment of Z2 is d21, the second radial segment is d22, and the third radial segment is d23. The first radial segment of Z3 is d31, the second radial segment is d32, and the third radial segment is d33. The first traction rope... The insertion method of the second traction rope 2 from end to beginning is as follows: the outer end of the mounting port 32 of d11 is between the pulley 33 and the inner end of the mounting port 32 of d21 is between the pulley 33 and the outer end of the mounting port 32 of d31 is between the pulley 33; the insertion method of the third traction rope 2 from end to beginning is as follows: the outer end of the mounting port 32 of d21 is between the pulley 33 and the inner end of the mounting port 32 of d22 is between the pulley 33 and the outer end of the mounting port 32 of d23 is between the pulley 33.

[0039] When the manipulator 11 extends, its axial dimension increases, causing a portion of the traction rope 2 to be released from the tension reel 4, thus passively lengthening the traction rope 2. The increased dynamic load on the actuator side caused by the lengthening of the traction rope 2 has a negligible impact on the overall functionality of the structure. As the traction rope 2 lengthens, the tension reel 4 applies a linear tension force to it, causing the tension on the traction rope 2 to adaptively increase with changes in axial dimension. By staggering the direction and position of the traction rope 2's movement, the radial displacement of the support plate 3 along the manipulator 11 can be further achieved, which ultimately provides the axial stiffness of the continuum robot. Furthermore, even after the three staggered movements are superimposed, the corresponding positional relationship between the beginning and end remains unchanged. Therefore, this mechanism achieves adaptive stiffness gain during the axial extension of the continuum robot.

[0040] The internal structure of the tensioning reel 4 is the same as that of the tension spring balancer in existing technology products, and will not be described further here.

[0041] When the manipulator 11 bends, its stiffness adaptive gain realization process is similar to that of the manipulator 11 extension condition. That is, the greater the bending amount of the flexible rod 111, the greater the elongation and the greater the supporting force provided. Under the bending condition of the manipulator 11, the three flexible rods 111 have different bending degrees, so the elongation is different, and the corresponding elongation of the traction rope is also different. The outermost flexible rod 111 has the largest bending degree. Assuming the typical bending condition of the manipulator 11 (the outermost flexible rod 111 elongates by 0.5m, the outermost flexible rod 111 bends by 45°, and the traction rope 2 corresponding to the outermost flexible rod 111 is offset by 5cm), the calculated disturbance of the outermost flexible rod 111 relative to the center arrangement is 3.18%. That is, the positional offset of the head and tail of the continuum robot is small under this condition, and the impact on the spatial operation accuracy is small.

[0042] Specifically, the front-end base 12 includes several fixed terminals 121 and connecting plates I 122. The number of sides of the connecting plate I 122 and the number of fixed terminals 121 correspond to the number of flexible rods 111, which is also three. One fixed terminal 121 is fixed at each angle of the connecting plate I 122, and the head end of each flexible rod 111 is fixed in the corresponding fixed terminal 121. The front-end base 12 serves to connect the heads of the three flexible rods 111 and can be used to mount suction cups, cameras, detectors, or mechanical grippers.

[0043] The front base 12 includes several drive terminals 131 and a connecting plate II 132. The number of side lengths of the connecting plate II 132 and the number of drive terminals 131 correspond to the number of flexible rods 111. Each included angle of the connecting plate II 132 is fixed with a drive terminal 131. The end of each flexible rod 111 passes through the corresponding drive terminal 131. The flexible rods 111 can move within the drive terminals 131.

[0044] The drive mechanism 14 includes a first drive mechanism 141, a second drive mechanism 142, and a third drive mechanism 143, which are independently set. The first drive mechanism 141, the second drive mechanism 142, and the third drive mechanism 143 are respectively fixed on three drive terminals 131 and can drive the movement of a flexible rod 111 respectively.

[0045] The thread profile of the flexible rod 111 is rectangular. The first drive mechanism 141, the second drive mechanism 142, and the third drive mechanism all include a DC motor 01, a reducer 02, a driving gear 03, a driven gear 04, a first sliding pin 05, a second sliding pin 06, and a third sliding pin 07. The drive terminal 131 includes two hollow cylinders 131a and 131b on the same axial direction. A gap is provided between the hollow cylinders 131a and 131b, and the two hollow cylinders 131a and 131b are connected by two spaced connecting ribs 131c. The front and rear ends of the connecting ribs 131c are respectively fixed to the circumferential surfaces of the hollow cylinders 131a and 131b. The driven gear 04 is positioned within the gap between the hollow cylinders 131a and 131b, and the two connecting ribs 131c are located on either side of the driven gear 04.

[0046] The diameter of the driven gear 04 is larger than the outer diameter of the rear hollow cylinder 131b. The tooth extension distance of the driven gear 04 is the same, and the driven gear 04 and the front hollow cylinder 131a are aligned axially. A reducer 02 and a DC motor 01 are fixed on the front and rear sides of each rear hollow cylinder 131b, respectively. The input end of the reducer 02 is connected to the output end of the DC motor 01. A driving gear 03 is fixed on the output end of the reducer 02. The driving gear 03 and the driven gear 04 mesh with each other. A cavity concentric with the driven gear 04 is provided in the middle of the driven gear 04. A first sliding pin 05, a second sliding pin 06, and a third sliding pin 07 are also provided. All are fixed to the curved inner wall of the cavity. The flexible rod 111 passes into the drive terminal 131. The first sliding pin 05 and the second sliding pin 06 are engaged on both sides of the thread on the outer wall of the flexible rod 111, and the line connecting the first sliding pin 05 and the second sliding pin 06 is parallel to the axis of the flexible rod 111. The third sliding pin 07 is engaged at the lower edge of the thread on the flexible rod 111. The plane where the third sliding pin 07 is located and the plane where the first sliding pin 05 is located are symmetrical about the central axis of the driven gear 04. The axial position of the third sliding pin 07 on the driven gear 04 is between the first sliding pin 05 and the third sliding pin 07. Two connecting ribs 131c are located on both sides of the driven gear 04, which can limit the movement of the driven gear 04, effectively ensuring the rotational accuracy of the driven gear 04 and preventing slippage.

[0047] When DC motor 01 starts, its output shaft rotates, driving the output end of reducer 02 to rotate, which in turn causes drive gear 03 to rotate, which in turn drives driven gear 04 to rotate. When driven gear 04 rotates, the three sliding pins slide within the grooves of flexible rod 111, causing the three flexible rods 111 to move relative to the three drive terminals 131. Of course, the rotation direction of DC motor 01 can be forward or reverse. During operation, the three flexible rods 111 move forward in unison most of the time. When encountering a turn, one or two flexible rods 111 temporarily retract to achieve self-adaptation, and then move forward again after passing the turn.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A continuum robot capable of self-adjusting stiffness, characterized in that, The system includes a continuous robot body (1), several traction ropes (2), several support discs (3), several tension reels (4), and several limiting springs (5). The continuous robot body (1) includes an operating arm (11), a front base (12), a rear base (13), and a drive mechanism (14). The operating arm (11) includes several axially parallel flexible rods (111). The ends of the flexible rods (111) are all fixed on the front base (12). The drive mechanism (14) is fixed on the rear base (13). The end of each flexible rod (111) can move axially independently within the rear base (13) under the drive of the drive mechanism (14). The tension reels (4) are all fixed on the front base (12). One end of the traction rope (2) is fixed on the inner side of the rear base (13), and the other end is wound on the tension reel (4). The support discs (3) include two adjacent first radial branch segments, a second... The radial branch segments and the third radial branch segment correspond in number to the flexible rod (111) and the traction rope (2). Several support discs (3) are distributed at intervals along the axial direction of the operating arm (11), and each branch segment is respectively sleeved on a flexible rod (111). The limiting spring (5) is sleeved on the flexible rod (111), so that the support discs (3) remain evenly spaced when the continuous robot body (1) is working dynamically. The traction rope (2) also passes through the corresponding branch segments in sequence. When the continuous robot is working dynamically, the traction rope (2) on one branch segment of each support disc (3) applies force to the outside of the continuous robot body (1), and the traction rope (2) on the other branch segments applies force to the inside of the continuous robot body (1). The position of the branch segment through which the traction rope (2) applies force to the outside of the continuous robot body (1) extends clockwise or counterclockwise along the axial direction of the operating arm (11).

2. A continuum robot capable of self-adjusting stiffness according to claim 1, characterized in that, Each branch of the support plate (3) has a through hole (31) at its outer end.

3. A continuum robot capable of self-adjusting stiffness according to claim 1, characterized in that, Each branch of the support plate (3) has a mounting port (32) in the middle. A pulley (33) is rotatably connected inside the mounting port (32). The rotation axis of the pulley (33) is perpendicular to the radial direction of the branch. A traction rope (2) on one branch of each support plate (3) is threaded between the inner end of the mounting port (32) and the pulley (33). The traction rope (2) on the other branch is threaded between the outer end of the mounting port (32) and the pulley (33). The position of the branch with the traction rope (2) threaded between the inner end of the mounting port (32) and the pulley (33) extends clockwise or counterclockwise along the axial direction of the operating arm (11).

4. A continuum robot capable of self-adjusting stiffness according to claim 1, characterized in that, The front base (12) includes a number of fixed terminals (121) and a connecting plate I (122). The number of side lengths of the connecting plate I (122) and the number of fixed terminals (121) correspond to the number of flexible rods (111). Each included angle of the connecting plate I (122) is fixed with a fixed terminal (121), and the head end of each flexible rod (111) is fixed in the corresponding fixed terminal (121).

5. A continuum robot capable of self-adjusting stiffness according to any one of claims 1-4, characterized in that, The rear base (13) includes a plurality of drive terminals (131) and a connecting plate II (132). The number of side lengths of the connecting plate II (132) and the number of drive terminals (131) correspond to the number of flexible rods (111). Each angle of the connecting plate II (132) is fixed with a drive terminal (131). The end of each flexible rod (111) is inserted into the corresponding drive terminal (131).

6. A continuum robot capable of self-adjusting stiffness according to claim 5, characterized in that, The drive mechanism (14) includes a first drive mechanism (141), a second drive mechanism (142), and a third drive mechanism (143) that are independently set. The first drive mechanism (141), the second drive mechanism (142), and the third drive mechanism (143) are respectively fixed on three drive terminals (131).

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