A driving device for a continuum robot

Abstract

A driving device for a continuum robot provided by the present invention comprises a base; a plurality of fixed pulleys and perforated plates arranged at intervals; a variable stiffness mechanism supported on the base and located between two adjacent perforated plates, which has M variable stiffness cams arranged coaxially with a first rotating shaft, and each variable stiffness cam changes the tension degree of a corresponding driving rope after passing through the fixed pulley by changing its own radius; a plurality of cam mechanism assemblies respectively arranged between two adjacent perforated plates, each cam mechanism assembly has M elastic driving cams arranged coaxially with a second rotating shaft, each driving cam is respectively provided with a follower at its upper part, each driving rope passes through the top end of a corresponding follower, during the rotation of the driving cam, the bottom end of the follower makes rolling contact with the top end of the driving cam and drives the follower to move along the radial direction of the driving cam through the change of the radius of the driving cam itself, so as to change the length of the driving rope. The present invention can reduce the number of driving motors, simplify the control difficulty and improve the stiffness of the continuum robot.

Description

Technical Field

[0001] The present invention belongs to the technical field of continuum robots, and particularly relates to a driving device for a continuum robot. Background Art

[0002] Due to its flexibility, continuum robots have broad application prospects in the fields of medical treatment, industry, and scientific research. However, there are also some deficiencies. For example, they have poor rigidity and can only work with low loads. In addition, the driving mechanism of continuum robots is relatively complex. Basically, each one or two driving ropes need to be connected to an actuator such as a motor. And a flexible continuum robot has at least ten or twenty-some driving ropes, which requires a large number of driving motors, resulting in too large a volume of the driving device, being not conducive to miniaturization, and the control program of a large number of driving motors becoming complex.

[0003] In addition, the continuum robot has weak stiffness. Common methods to improve stiffness include blocked variable stiffness, adding airbags and blockers in the continuum. By changing the air pressure, the friction force is increased, thereby improving the stiffness. This type of variable stiffness method makes the structure of the continuum robot bloated and requires a high-power air pump. In addition to this, adding special materials to the continuum can also improve the stiffness. This material has two states, solid and liquid, and the stiffness is improved by changing the state. This method has low efficiency, and the transformation of the solid-liquid state of the material requires time and conditions. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] For this reason, the driving device for a continuum robot provided by the present invention can reduce the number of required driving motors to meet the miniaturization requirement and simplify the control difficulty. At the same time, it can also improve the stiffness of the continuum robot and ensure smoother and more stable bending of the continuum robot.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The driving device for a continuum robot provided by the present invention includes a base, a rope-laying mechanism, a variable stiffness mechanism, and a driving mechanism;

[0008] One end of the base is provided with a connector for installing the end of the continuum robot. The continuum robot has N bending segments and is driven by a total of M driving ropes;

[0009] The rope-laying mechanism includes a plurality of fixed pulleys and N + 2 rope hole plates arranged at intervals; each fixed pulley is distributed in the area of the base close to the connector for dispersing and guiding the driving ropes; the spacing direction between two adjacent rope hole plates is consistent with the axial direction of the base, and each rope hole plate is provided with a rope-passing hole corresponding to the position of each fixed pulley to constrain the corresponding driving rope;

[0010] The variable stiffness mechanism is supported on the base and located between two adjacent rope hole plates. Areas for installing the fixed pulley and the driving mechanism are respectively formed outside the two rope hole plates. There are M variable stiffness cams arranged coaxially with a first rotating shaft in the variable stiffness mechanism. Each variable stiffness cam changes the tension of a corresponding driving rope passing through the fixed pulley by varying its own radius.

[0011] The driving mechanism includes N cam mechanism components. One cam mechanism component is respectively arranged between two adjacent rope hole plates for driving a corresponding bending section of the continuum robot. There are M driving cams arranged coaxially with a second rotating shaft in a single cam mechanism component. Driven members are respectively arranged on the upper parts of the driving cams. Rope passing holes for passing through a corresponding driving rope are respectively arranged at the tops of the driven members. Each driving cam is a variable diameter cam with elasticity, and the elasticity of the driving cam is utilized to ensure its smooth rotation. During the rotation of the driving cam, the bottom end of the driven member makes rolling contact with the top end of the driving cam and drives the driven member to move radially along the driving cam through the change of the radius of the driving cam itself, thereby changing the rope length of the driving rope and causing a corresponding rotation angle of the driven bending section.

[0012] In some embodiments, the first rotating shaft and each second rotating shaft in the cam mechanism component are at the same height, and their axes are both perpendicular to the running direction of the driving rope in the base.

[0013] In some embodiments, the variable stiffness mechanism further includes a first motor fixed on the side wall of the base for driving the first rotating shaft. The M variable stiffness cams rotate synchronously with the first rotating shaft, and the radius of the variable stiffness cam gradually changes as the central angle of the variable stiffness cam increases.

[0014] In some embodiments, when it is necessary to tension the driving rope, the first rotating shaft is driven to make the variable stiffness cam rotate in the direction of increasing its radius. When it is necessary to relax the driving rope, the first rotating shaft is driven to make the variable stiffness cam rotate in the direction of decreasing its radius.

[0015] In some embodiments, the cam mechanism component further includes a second motor fixed on the side wall of the base for driving the rotating shaft. The M driving cams rotate synchronously with the second rotating shaft. The outer peripheral surface of the driving cam is divided into three curved surface segments. Let the central angles corresponding to the three curved surface segments be α 1, α 2, α 3, and simultaneously satisfy: α 1 ∈ (90°, 180°), α2 ∈ (90°, 180°), α 1 + α 2 + α 3 = 360°, where the first curved surface segment and the second curved surface segment are working segments, and the central angles α 1 and α 2 are the ranges of the driving cam rotating clockwise and counterclockwise respectively, which determine the rotation direction and rotation range of a bending segment of the driven continuum robot. The radius of the driving cam gradually changes with the increase of its respective central angle within the range of each working segment; the third curved surface segment is a transition segment that smoothly connects the first curved surface segment and the second curved surface segment.

[0016] In some embodiments, the driving cam is a solid structure made of an elastic material; or,

[0017] the driving cam is a hollow structure, and the hollow structure includes an outer ring and an inner ring arranged coaxially with the second axis and a plurality of support members circumferentially distributed and connected between the outer ring and the inner ring. Both the outer ring and the inner ring are made of a rigid material, and the support members are elastic elements.

[0018] In some embodiments, the number of the support members is 6 - 8, and they are springs or S-shaped structures made of the same material as the outer ring and the inner ring.

[0019] In some embodiments, the outer contour of a certain working segment of the driving cam is determined according to the following steps:

[0020] First, according to the structure and the rope threading method of the continuum robot, a series of driving rope length change values corresponding to a series of bending angle values of the controlled continuum are determined; then, according to the geometric position relationship between the second rotating shaft and the rope hole plates on its two sides, a series of radius values of a certain working segment of the driving cam are calculated from the series of driving rope length change values, and the series of radius values are evenly distributed within the central angle range of a certain working segment of the driving cam, so as to obtain the outer contour of a certain working segment of the driving cam.

[0021] Let the length change of the driving rope caused by the radius change Δ r of the driving cam be Δ l , and the relationship between Δ r and Δ l is as follows:

[0022]

[0023] where, l 3 is the vertical distance between the follower on the driving cam and the rope hole plates on its two sides; l4 is the height difference between the follower and the corresponding rope passing hole on the rope hole plate when the driving cam does not rotate.

[0024] In some embodiments, the driving mechanism further includes a limiting component fixedly connected to the base, configured to keep the bottom end of the follower in contact with the top end of the driving cam, and restrict the follower to move only in the radial direction of the driving cam.

[0025] In some embodiments, the limiting component includes N cross beams, with an end cover provided at the top end of each cross beam. Each cross beam is located above a corresponding cam mechanism component and fixedly connected to the base. A plurality of limiting through holes for the followers in the cam mechanism components to pass through are formed on the cross beam. A limiting piece with a cross-sectional dimension matching that of the limiting through hole is fixedly provided on the follower to limit the rotation of the follower in the limiting through hole; a plurality of second through holes for the top parts of the followers to extend out are formed on the end cover, and a compression spring fixedly connected to the limiting piece is respectively provided in each second through hole.

[0026] The driving device of the continuum robot provided by the present invention has the following characteristics and beneficial effects:

[0027] 1. Multiple cams with variable radii are arranged on a single motor shaft to achieve the function of a single motor controlling multiple driving ropes simultaneously, reducing the number of driving motors in the driving device, lowering the complexity of the driving device, and simplifying the control program.

[0028] 2. During the rotation of the variable stiffness cam, the driving rope can be tightened by using its own radius change. Through the mutual antagonistic action of multiple driving ropes, the effect of improving the stiffness of the continuum robot is achieved.

[0029] 3. An elastic variable-diameter cam is used as the driving cam, and its own elasticity is utilized to ensure the smooth rotation of the driving cam, thereby ensuring smoother and more stable bending of the continuum robot; the outer contour of the driving cam is divided into two working sections and a transition section connecting the two. For each working section, precise control of the rotation direction and rotation range of a certain bending section of the driven continuum robot is achieved through the radius change of the driving cam itself, while the transition section can ensure the stability of the system when the control accuracy is relatively low. Description of the Drawings

[0030] Figure 1 is the overall structural schematic diagram of a driving device of a continuum robot provided by an embodiment of the present invention;

[0031] Figure 2 is Figure 1 the structural schematic diagram of the first cam mechanism component in the shown driving device;

[0032] Figure 3 is Figure 2 Schematic diagram of the structure of a single driving cam in the first cam mechanism assembly shown;

[0033] Figure 4 is for Figure 3 Schematic diagram for designing the radius of the driving cam shown;

[0034] Figure 5 Schematic diagram of the structure of an improved driving cam provided in this embodiment;

[0035] Figure 6 is Figure 1 Schematic diagram of the structure of the limit component in the driving device shown;

[0036] Figure 7 is Figure 1 Schematic diagram of the layout of the driving rope in the driving device shown.

[0037] Label description:

[0038] 100 - Driving device; 110 - Base, 111 - First side wall, 112 - Second side wall, 113 - Connecting piece; 120 - Rope laying mechanism, 121 - Fixed pulley, 122 - Stud, 123 - First rope hole plate, 124 - Second rope hole plate, 125 - Third rope hole plate, 126 - Fourth rope hole plate; 130 - Variable stiffness mechanism, 131 - First motor, 132 - Variable stiffness cam, 133 - First bearing seat; 140 - First cam mechanism assembly; 141 - Second motor, 142 - Driving cam, 142a - First curved surface section, 142b - Second curved surface section, 142c - Third curved surface section, 142d - First through hole, 142’ - Improved driving cam, A - Outer ring, B - Inner ring, C - Support piece, 143 - Second bearing seat, 144 - Driven part, 144a - Rope passing hole, 145 - Second rotating shaft, 146 - Coupling; 150 - Second cam mechanism assembly; 160 - Limit component, 161 - Longitudinal beam, 162 - Cross beam, 162a - Limit through hole, 163 - End cover, 163a - Second through hole, 164 - Limit piece, 165 - Compression spring; 170 - Driving rope;

[0039] 200 - Continuum robot. Detailed implementation manners

[0040] In order to make the objectives, technical solutions and advantages of this application clearer, the following further describes this application in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0041] Rather, this application covers any alternatives, modifications, equivalent methods, and solutions defined by the claims that fall within the spirit and scope of this application. Further, for the purpose of enabling the public to better understand this application, in the following detailed description of this application, some specific details are described in detail. Those skilled in the art can fully understand this application even without the description of these details.

[0042] The structures, proportions, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the conditions for the implementation of this application. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that this application can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope of implementation of this application. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which this application can be implemented.

[0043] See Figure 1 , a driving device 100 of a continuum robot provided by an embodiment of the present invention includes a base 110, a rope laying mechanism 120, a variable stiffness mechanism 130, and a driving mechanism;

[0044] The base 110, one end of the base 110 is provided with a connecting member 113 for installing the end of the continuum robot 200. The continuum robot 200 has N bending segments and is driven by a total of M driving ropes 170;

[0045] The rope laying mechanism 120 includes a plurality of fixed pulleys 121 and N + 2 spaced rope hole plates (123 to 126); each fixed pulley 121 is distributed in the area of the base 110 close to the connecting member 113. Through the guiding action of the fixed pulley 121, the driving ropes 170 are dispersed and the walking directions are ensured to be parallel; the spacing direction between adjacent two rope hole plates is consistent with the axial direction of the base 110, and each rope hole plate is provided with a rope passing hole corresponding to the position of each fixed pulley 121 to restrict the corresponding driving rope 170;

[0046] The variable stiffness mechanism 130 is supported on the base 110 and is located between two adjacent rope hole plates, and the outer sides of these two rope hole plates are respectively the areas for installing the fixed pulley 121 and the driving mechanism. The variable stiffness mechanism 130 has M variable stiffness cams 132 arranged coaxially with the first rotating shaft. The first rotating shaft is perpendicular to the walking direction of the driving rope 170. Each variable stiffness cam 132 changes the tension of a corresponding driving rope 170 after passing through the fixed pulley 121 by changing its own radius;

[0047] The driving mechanism includes N cam mechanism components (140, 150). One cam mechanism component is provided between two adjacent rope hole plates respectively, which is used to drive a corresponding bending section of the continuum robot 200. There are M driving cams with a common rotating shaft arranged in a single cam mechanism component. Driven parts are respectively arranged on the upper parts of the driving cams. Rope-passing holes for passing through a corresponding driving rope 170 are respectively arranged at the tops of the driven parts. Each driving cam adopts a variable-diameter cam with elasticity to ensure its smooth rotation by utilizing the elasticity of the driving cam. During the rotation of the driving cam, the bottom end of the driven part makes rolling contact with the top end of the driving cam, and the driven part is driven to move along the radial direction of the driving cam through the radius change of the driving cam itself, so as to change the rope length of the driving rope 170 and make the driven bending section generate a corresponding rotation angle.

[0048] Next, a specific application example will be used to describe in detail the specific implementation manner of the driving device 100 of this embodiment in conjunction with the accompanying drawings. The driving device 100 of this embodiment is used to drive a common continuum robot 200 on the market. The continuum robot 200 is composed of several threading discs and intermediate elastic rods, has two bending degrees of freedom (i.e., N = 2), and is driven by a total of M = 12 driving ropes 170. Each bending section is respectively controlled by 6 driving ropes.

[0049] See Figures 1 to 5 , the driving device 100 of this embodiment includes:

[0050] A base 110, and a connecting piece 113 for installing the end of the continuum robot 200 is provided at one end of the base 110;

[0051] A rope-laying mechanism 120, including M fixed pulleys 121 and 4 spaced rope hole plates (123 - 126); each fixed pulley 121 is distributed in the area of the base 110 close to the connecting piece 113 through a stud 122. Through the guiding action of the fixed pulley 121, the driving ropes 170 are dispersed and the running directions are ensured to be parallel; the spacing direction between two adjacent rope hole plates is consistent with the axial direction of the base 110, and rope-passing holes corresponding to the positions of the fixed pulleys 121 are provided on each rope hole plate to restrict the corresponding driving ropes 170;

[0052] A variable stiffness mechanism 130 is supported on the base 110 and is located between the first rope hole plate 123 and the second rope hole plate 124. The outer sides of these two rope hole plates are respectively the areas for installing the fixed pulleys 121 and the driving mechanism. There are M variable stiffness cams 132 with a common first rotating shaft arranged in the variable stiffness mechanism 130. The first rotating shaft is perpendicular to the running direction of the driving rope 170. Each variable stiffness cam 132 changes the tension of a corresponding driving rope 170 after passing through the fixed pulley 121 through its own radius change;

[0053] The driving mechanism includes a first cam mechanism assembly 140 and a second cam mechanism assembly 150. The first cam mechanism assembly 140 is located between the second rope hole plate 124 and the third rope hole plate 125, and the second cam mechanism assembly 150 is located between the third rope hole plate 125 and the fourth rope hole plate 126, and is used to drive a corresponding bending section of the continuum robot 200; there are M driving cams arranged coaxially in a single cam mechanism assembly, and followers are respectively arranged on the upper parts of the driving cams, and rope passing holes for passing through a corresponding driving rope 170 are respectively arranged at the tops of the followers; each driving cam is a variable-diameter cam with elasticity, and the elasticity of the driving cam is used to ensure its smooth rotation. During the rotation of the driving cam, the bottom end of the follower makes rolling contact with the top end of the driving cam and drives the follower to move radially along the driving cam through the radius change of the driving cam itself, so as to change the rope length of the driving rope 170 and make the driven bending section generate a corresponding rotation angle.

[0054] Further, the base 110 is mainly used to install and position the components in this embodiment and is connected to the end of the driven continuum robot 200. The length direction (defined as its axial direction) of the base 110 is parallel to the running direction of the driving rope 170. The base 110 is divided into several regions along its axial direction by the rope hole plates in the rope laying mechanism 120. Among them, each fixed pulley 121 of the rope laying mechanism 120 is arranged in the region close to the end of the continuum robot 200, and the variable stiffness mechanism 130, the first cam mechanism assembly 140 and the second cam mechanism assembly 150 are sequentially arranged in the regions between the remaining adjacent two rope hole plates. The length directions (defined as their respective axial directions) of the variable stiffness mechanism 130, the first cam mechanism assembly 140 and the second cam mechanism assembly 150 are all perpendicular to the axial direction of the base 110, and their two ends are respectively supported on the first side wall 111 and the second side wall 112 of the base 110.

[0055] Further, in the rope laying mechanism 120, each fixed pulley 121 is fixed on the base 110 through a stud 122 respectively, which serves to disperse and lay the driving ropes 170 flat. Rope passing holes are respectively arranged at set positions on the four rope hole plates (123, 124, 125, 126), and their positions correspond to the positions of the fixed pulleys 121, which are used to restrain the driving ropes 170 to prevent the driving ropes 170 from shifting and misaligning. The ends of the driving ropes 170 are finally fixed on the fourth rope hole plate 126. The four rope hole plates (123, 124, 125, 126) are all fixed on the base 110 by screws.

[0056] Further, the variable stiffness mechanism 130 includes a first motor 131, a first rotating shaft, and M variable stiffness cams 132. The first motor 131 is fixed on the first side wall 111 of the base 110 between the first rope hole plate 123 and the second rope hole plate 124. The output end of the first motor 131 is connected to one end of the first rotating shaft. The first rotating shaft is driven by the first motor 131 to rotate. The M variable stiffness cams 132 are fixedly sleeved on the first rotating shaft and rotate synchronously with the first rotating shaft. The other end of the first rotating shaft is supported on the second side wall 112 of the base 110 between the first rope hole plate 123 and the second rope hole plate 124 through a first bearing block 133. Each variable stiffness cam 132 is a variable diameter cam. Specifically, the radius of the variable stiffness cam 132 gradually increases or decreases as the central angle of the variable stiffness cam 132 increases. When it is necessary to tension the drive rope 170, the first motor 131 is used to drive the first rotating shaft to make the variable stiffness cam 132 rotate in the direction of increasing its radius. When it is necessary to relax the drive rope 170, the first motor 131 is used to drive the first rotating shaft to make the variable stiffness cam 132 rotate in the direction of decreasing its radius. When the drive rope 170 is tensioned, the binding force generated between the drive ropes 170 is similar to the mutual antagonistic effect between antagonist muscles, thereby improving the stiffness of the continuum robot 200. The mutual antagonistic effect described in this article can refer to muscle antagonism, which is a part of the human muscles. It is the muscle that relaxes and elongates simultaneously on the opposite side of the prime mover during the process of the prime mover contracting to complete the action. For example, in the process of completing the elbow flexion action, the prime movers are the biceps brachii and the brachialis. The triceps brachii on the opposite side of them relaxes and elongates simultaneously and is the antagonist muscle in the elbow flexion action, and vice versa. The antagonist muscle and the prime mover are formally opposite, but their functions around the joint movement are unified and coordinated.

[0057] Further, the components of each cam mechanism in the driving mechanism are the same. Now, the first cam mechanism component 140 is taken as an example for illustration. Referring to FIG. 2, the first cam mechanism component 140 includes a second motor 141, a second rotating shaft 145, M driving cams 142, and M driven members 144. The second motor 141 is fixed on the first side wall 111 of the base 110 between the second rope hole plate 124 and the third rope hole plate 125. The output end of the second motor 141 is connected to one end of the second rotating shaft 145. The second rotating shaft 145 is driven to rotate by the second motor 141. The M driving cams 142 are fixedly sleeved on the second rotating shaft 145 and rotate synchronously with the second rotating shaft 145. The other end of the second rotating shaft 145 is supported on the second side wall 112 of the base 110 between the second rope hole plate 124 and the third rope hole plate 125 through a second bearing block 143. During the rotation of the driving cam 142, the bottom end of the driven member 144 remains in rolling contact with the top end of the driving cam 142. A rope passing hole 144a for passing through a corresponding driving rope 170 is provided at the top end of the driven member 144. Optionally, a coupling 146 is further provided between the output end of the second motor 141 and the second rotating shaft 145 to ensure smooth power transmission.

[0058] Further, referring to Figure 3 , which is a schematic structural diagram of a certain driving cam 142 in the first cam mechanism component 140, and the other driving cams are similar to it. Except for a first through hole 142d provided in the middle of the driving cam 142 for fitting and assembling with the second rotating shaft 145, the rest of the driving cam 142 is a solid structure. In this embodiment, both the second rotating shaft 145 and the first through hole 142d of the driving cam 142 have a square cross-section. Considering that during the driving of the continuum robot 200, there is a situation where the tension of some driving ropes 170 is too large. If a rigid driving cam is used, there will be a situation where the driving rope 170 is broken or the continuum robot 200 is stuck and cannot move. In addition, considering the possible errors during the processing and assembly of this driving device, it will also lead to the situation where the tension of the driving rope 170 is too large. Therefore, each driving cam 142 is made of an elastic material, and the elasticity of the driving cam itself is used to ensure that the driving cam can rotate smoothly, thereby ensuring that the bending of the continuum robot 200 is more smooth and stable. The driving cam 142 is a variable-diameter cam. The outer peripheral surface of the driving cam 142 is divided into three curved surface segments, which are respectively denoted as a first curved surface segment 142a, a second curved surface segment 142b, and a third curved surface segment 142c. Let the central angles corresponding to the three curved surface segments be α 1, α 2, α 3, and at the same time satisfy: α 1 ∈ (90°, 180°), α 2 ∈ (90°, 180°), α 1 + α 2 + α3 = 360°, where the first curved surface segment 142a and the second curved surface segment 142b are working segments, and the central angles α 1 and α 2 are the ranges for the driving cam 142 to rotate clockwise and counterclockwise respectively, which determine the rotation direction and rotation range of a certain bending segment of the driven continuum robot 200. The radius of the driving cam 142 is set to gradually change with the increase of its respective central angle within the range of each working segment; the third curved surface segment 142c is a transition segment connecting the first curved surface segment 142a and the second curved surface segment 142b, so that the central angle of the outer contour of the driving cam 142 is 360°. The driving rope 170 generally does not pass through the third curved surface segment 142c. When the control accuracy of this device decreases, it may occur that the driving rope 170 passes through a small part of the third curved surface segment 142c, which plays a role in stabilizing the system. It can be understood that setting the central angle in this way can make full use of the entire outer peripheral surface of the driving cam 142. If the central angle α 1, α 2 are both less than or equal to 90 degrees, then will be greater than or equal to 180 degrees, resulting in the underutilization of the outer peripheral surface of the driving cam 142; if the central angles α 1, α 2 are both equal to 180 degrees, there will be a lack of a transition segment, and the first curved surface segment 142a and the second curved surface segment 142b are directly connected, and a sudden change in the radius of the driving cam may occur at their connection, which is not conducive to the stability of the system.

[0059] The following briefly describes the design process of each curved surface segment of the driving cam 142:

[0060] The design of the curved surface segment of the driving cam 142 is related to its corresponding driving rope 170. First, according to the structure and rope threading method of the continuum robot 200, the relationship between the bending angle of the controlled continuum and the length change of the driving rope 170 is calculated; then, according to the geometric position relationship between the second rotating shaft 145 and the rope hole plates on both sides of the second rotating shaft 145, the relationship between the bending angle of the controlled continuum and the radius of the driving cam 142 is further calculated. For a series of angle values of the controlled continuum bending in one direction, a series of values corresponding to the radius of the driving cam 142 will be calculated, and these values are evenly distributed within the central angle α 1 (such as 150 degrees) of the first curved surface segment 142a of the driving cam 142, so as to obtain the first curved surface segment 142a of the driving cam 142. Similarly, for the working condition of the continuum robot 200 bending in the reverse direction, the second curved surface segment 142b of the driving cam can be obtained according to the same steps as above. The third curved surface segment 142c is a transition contour and does not need to be calculated. Only a smooth transition is required to connect the first curved surface segment 142a and the second curved surface segment 142b of the driving cam 142.

[0061] Furthermore, referring toFigure 4 When the driving cam 142 is not rotating and is in the initial position, the follower 144 and the driving rope 170 are in the solid line position; when the driving cam 142 rotates in the direction of increasing its radius, the follower 144 and the driving rope 170 are in the dashed line position. Since the present invention does not involve the design of the configuration of the continuum robot 200 itself, and it uses a continuum robot with a common configuration that already exists, the relationship between the bending angle of the controlled continuum and the change in the rope length of the driving rope 170 is used as a known condition and will not be separately calculated and described. Let the displacement of the follower 144 along the radial direction of the driving cam 142 be h , the radius change value of the driving cam 142 be Δ r , and it satisfies Δ r = h . Let the change in the length of the driving rope 170 caused by the radius change of the driving cam 142 be Δ l . The initial length and the changed length of the driving rope 170 between the second rope hole plate 124 and the third rope hole plate 125 are respectively l 1, l 2. By listing equations through the geometric relationship shown in Figure 4 :

[0062]

[0063] Combining the above three equations, we get:

[0064]

[0065] Among them, l 3 is the vertical distance between the follower 144 and the second rope hole plate 124 and the third rope hole plate 125 on both sides of it, and they are taken to be equal; l 4 is the height difference between the rope hole 144a on the follower 144 and the rope hole on the second rope hole plate 124 when the driving cam is not rotating, l 3 and l 4 are both known values.

[0066] Based on the above formula, the relationship between the radius change value Δ r of the driving cam 142 and the change Δ l in the rope length of the driving rope 170 can be obtained, and then the relationship between the radius change value Δ r of the driving cam 142 and the bending angle of the controlled continuum can be obtained.

[0067] Furthermore, an improved driving cam 142' is proposed in the embodiment of the present invention. The difference between it and the driving cam 142 is that this improved driving cam 142' has a part of its shape hollowed out, and a support member C is arranged in the hollowed-out part to form a structure similar to a hub. Specifically, see Figure 5, the improved drive cam 142' includes an outer ring A and an inner ring B disposed on a common second axis 145, and a plurality of support members C that are circumferentially evenly distributed and connected between the outer ring A and the inner ring B. The number of support members C is preferably set to 6 to 8. Both the outer ring A and the inner ring B are made of rigid materials. The support member C is a rigid material and has an S-shaped structure integrally formed with the inner and outer rings. Both ends of the S-shaped structure are linear and point to the axis of the drive cam; alternatively, the support member C is an elastic element, such as a spring. In this embodiment, the support member C has an S-shaped structure integrally formed with the inner and outer rings. The thickness a of the support member C is 0.5 mm, the distance from the outer peripheral surface of the inner ring B to the outer peripheral surface of the outer ring A is b = 9 mm, and the distance between the outer peripheral surface of the inner ring B and the inner peripheral surface of the outer ring A is c = 6 mm. The improved drive cam 142' is obtained by 3D printing with a resin material. The outer peripheral surfaces of the outer ring A and the inner ring B are equidistant curves, which is the same as the design process of the outer peripheral surface of the drive cam 142 and is also divided into three curved surface segments, which will not be elaborated here. After adding the support member C, when the displacement of the inner ring B is restricted and the force received by the outer ring A exceeds a certain threshold, the support member C will be compressed and undergo elastic deformation, causing the outer ring A to move in the direction of the force, ensuring that the bending of the continuum robot 200 is smoother and more stable. Compared with the drive cam 142, the improved drive cam 142' has a lighter self-weight. In addition, since the outer ring A of the improved drive cam 142' is made of a rigid material, it has better control accuracy compared with the drive cam 142.

[0068] Further, in order to ensure that the drive cam 142 and its corresponding follower 144 can maintain a rolling contact state during the operation of the drive device 100, the drive mechanism of this embodiment further includes a limit assembly 160. See Figure 1 , Figure 2 , Figure 6, the limiting component 160 includes a frame formed by fixedly connecting two longitudinal beams 161 and a plurality of cross beams 162. End caps 163 are respectively arranged at the tops of the cross beams 162. The axial directions of the two longitudinal beams 161 are consistent with the axial direction of the base 110 and are respectively fixed to the tops of the first side wall 111 and the second side wall 112 of the base 110 by bolts. The number of the cross beams 162 and the end caps 163 is the same as the number of the cam mechanism components in the driving mechanism. In this embodiment, there are two cross beams 162 and two end caps 163. Each cross beam 162 is respectively fixed above a corresponding cam mechanism component through the longitudinal beam 161. Limiting through holes 162a corresponding to the driven members 144 in the cam mechanism component are formed in the cross beams 162. Each driven member 144 passes through a corresponding limiting through hole 162a, and a limiting piece 164 with a cross-sectional size matching that of the limiting through hole 162a is fixedly arranged on the driven member 144 for restricting the rotation of the driven member 144 in the limiting through hole 162a. In this embodiment, both the limiting piece 164 and the limiting through hole 162a have a square cross-section. The limiting piece 164 can move along the axial direction (i.e., the up-and-down direction) of the limiting through hole 162a in the limiting through hole 162a along with the driven member 144, but cannot rotate; the axial directions of the end caps 163 are consistent with those of the cross beams 162. A plurality of second through holes 163a are formed in the end caps 163 for the tops of the corresponding driven members 144 to extend out respectively. Compression springs 165 fixedly connected to the limiting pieces 164 on the corresponding driven members 144 are respectively arranged in the second through holes 163a for ensuring that the bottom ends of the driven members 144 are in full contact with the tops of the driving cams 142.

[0069] Further, referring to Figure 7 , which is a wire threading schematic diagram of the driving device 100 of this embodiment. In this example, the continuum robot 200 is divided into two segments with a total of two degrees of freedom. The first segment bends up and down, and the second segment bends left and right. Each is driven by six ropes, with a total of 12 driving ropes 170. In this driving device 100, there is a variable stiffness mechanism 130, and a first cam mechanism component 140 and a second cam mechanism component 150 respectively controlling the movements of the two segments of the continuum. Therefore, if the continuum robot 200 is divided into N segments in total, then a total of N + 1 cam rotation shafts need to be arranged, and the number of cams on each rotation shaft should correspond to the number of the driving ropes 170. If the present invention is used to drive other continuum robots, the number of cam rotation shafts and the number of cams on the cam rotation shafts need to be increased or decreased according to the number of segments (the number of degrees of freedom) and the number of driving ropes of the continuum robot.

[0070] Taking the driving rope 170 in this example as an example, referring to Figure 7, after the driving rope 170 departs from the continuum robot 200, it first passes through the connecting member 113, then passes through the guiding and dispersing of the fixed pulley 121, passes through the first rope hole plate 123, bypasses the lower contour of the variable stiffness cam 132, and then passes through the second rope hole plate 124, the rope passing hole 144a of the follower on the driving cam in the first cam mechanism assembly 140, the third rope hole plate 125, and the rope passing hole of the follower on the driving cam in the second cam mechanism assembly 150 in sequence, and is finally fixed on the fourth rope hole plate 126. When each motor drives the corresponding rotating shaft to drive the driving cam to rotate, the follower moves up and down, causing the rope length of the driving rope 170 to change, thereby causing the continuum robot 200 to bend. It should be noted that all the rotating shafts are arranged in parallel and at the same height, and the rotating shaft is perpendicular to the running direction of the driving rope in this driving device.

[0071] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0072] Although the examples of the present invention have been shown and described above, it can be understood that the above examples are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above examples within the scope of the present invention.

Claims

1. A driving device for a continuum robot, characterized in that, It includes a base, a rope laying mechanism, a variable stiffness mechanism and a driving mechanism; One end of the base is provided with a connector for installing the end of the continuum robot. The continuum robot has N bending segments and is driven by M driving ropes in total; The rope laying mechanism includes several fixed pulleys and N + 2 rope hole plates arranged at intervals; each fixed pulley is distributed in the area of the base close to the connector for dispersing and guiding the driving ropes; the spacing direction between two adjacent rope hole plates is consistent with the axial direction of the base, and each rope hole plate is provided with a rope passing hole corresponding to the position of each fixed pulley to restrain the corresponding driving rope; The variable stiffness mechanism is supported on the base and located between two adjacent rope hole plates, and areas for installing the fixed pulley and the driving mechanism are respectively formed outside the two rope hole plates. There are M variable stiffness cams arranged coaxially with the first rotating shaft in the variable stiffness mechanism. Each variable stiffness cam changes the tension of a corresponding driving rope after passing through the fixed pulley by changing its own radius; The driving mechanism includes N cam mechanism components, and one cam mechanism component is respectively arranged between two adjacent rope hole plates for driving a corresponding bending segment of the continuum robot; there are M driving cams arranged coaxially with the second rotating shaft in a single cam mechanism component. Driven members are respectively arranged on the upper parts of the driving cams, and rope passing holes for passing through a corresponding driving rope are respectively arranged at the tops of the driven members; each driving cam is a variable diameter cam made of an elastic material, and the elasticity of the driving cam is used to ensure its smooth rotation. During the rotation of the driving cam, the bottom end of the driven member makes rolling contact with the top end of the driving cam and drives the driven member to move radially along the driving cam through the change of the radius of the driving cam itself, so as to change the rope length of the driving rope and make the driven bending segment generate a corresponding rotation angle.

2. The drive device according to claim 1, characterized in that, The first rotating shaft and each second rotating shaft in the cam mechanism component are at the same height, and their axes are all perpendicular to the running direction of the driving rope in the base.

3. The drive device according to claim 1, characterized in that, The variable stiffness mechanism further includes a first motor fixed on the side wall of the base for driving the first rotating shaft. The M variable stiffness cams rotate synchronously with the first rotating shaft, and the radius of the variable stiffness cam gradually changes as the central angle of the variable stiffness cam increases.

4. The drive device according to claim 1, characterized in that, When it is necessary to tension the driving rope, the first rotating shaft is driven to make the variable stiffness cam rotate in the direction of increasing its radius. When it is necessary to relax the driving rope, the first rotating shaft is driven to make the variable stiffness cam rotate in the direction of decreasing its radius.

5. The drive device according to claim 1, characterized in that, The cam mechanism assembly further includes a second motor fixed to the side wall of the base for driving the rotating shaft, and the M driving cams rotate synchronously with the second rotating shaft; the outer peripheral surface of the driving cam is divided into three curved surface segments, and let the central angles corresponding to the three curved surface segments be α 1, α 2, α 3, and at the same time satisfy: α 1 ∈ (90°, 180°), α 2 ∈ (90°, 180°), α 1 + α 2 + α 3 = 360°, where the first curved surface segment and the second curved surface segment are working segments, and the central angles α 1 and α 2 are the ranges of the clockwise rotation and counterclockwise rotation of the driving cam respectively, which determine the rotation direction and rotation range of a certain bending segment of the driven continuum robot. The radius of the driving cam gradually changes with the increase of its respective central angle within the range of each working segment; the third curved surface segment is a transition segment that smoothly connects the first curved surface segment and the second curved surface segment.

6. The drive device according to claim 5, characterized in that The driving cam is a solid structure made of an elastic material; or, The driving cam is a hollow structure, which includes an outer ring and an inner ring arranged coaxially with the second shaft and a plurality of support members connected between the outer ring and the inner ring and circumferentially distributed. The outer ring and the inner ring are both made of rigid materials, and the support members are elastic elements.

7. The drive device according to claim 6, characterized in that The number of the support members is 6 - 8, and springs or S-shaped structures made of the same materials as the outer ring and the inner ring are adopted.

8. The drive device according to any one of claims 5 to 7, characterized in that, Determine the outer contour of a certain working section of the driving cam according to the following steps: First, according to the structure and the rope threading method of the continuum robot, a series of driving rope length change values corresponding to a series of bending angle values of the controlled continuum are determined; subsequently, according to the geometric positional relationship between the second rotating shaft and the rope hole plates on its two sides, a series of radius values of a certain working section of the driving cam are calculated from the series of driving rope length change values, and the series of radius values are evenly distributed within the central angle range of a certain working section of the driving cam, thereby obtaining the outer contour of a certain working section of the driving cam. Let the change in the length of the drive rope caused by the change in the radius Δ of the drive cam be Δ r , and the following relationship is satisfied between Δ l and Δ r : l ​ Wherein, l 3 is the vertical distance between the follower on the driving cam and the rope hole plates on both sides thereof; l 4 is the height difference between the follower and the corresponding rope passing holes on the rope hole plate when the driving cam is not rotating.

9. The drive device according to claim 1, characterized in that, The driving mechanism further includes a limiting component fixedly connected to the base, which is used to keep the bottom end of the driven member in contact with the top end of the driving cam and to restrict the driven member to move only radially along the driving cam.

10. The drive device according to claim 9, characterized in that, The limiting component includes N cross beams. End caps are respectively arranged at the top ends of the cross beams. Each cross beam is located above a corresponding cam mechanism component and is fixedly connected to the base. A number of limiting through holes for the driven members in each cam mechanism component to pass through are formed in the cross beams. Limiting pieces with cross-sectional dimensions matching those of the limiting through holes are fixedly arranged on the driven members, which are used to restrict the rotation of the driven members in the limiting through holes; second through holes for the tops of the driven members to extend out are formed in the end caps, and compression springs fixedly connected to the limiting pieces are respectively arranged in the second through holes.

Images