A multi-section flexible robot arm and flexible robot

Abstract

This invention relates to a multi-segment flexible robotic arm and a flexible robot. The flexible robotic arm includes at least two interconnected flexible segments, each of which can perform bending motion under the antagonistic rotational drive of at least two flexible drive rods. The flexible drive rods are provided with threaded sections. Each flexible segment includes an end joint, multiple channel joints, and multiple drive joints. The multiple drive joints are threadedly engaged with the at least two flexible drive rods through threaded connection holes corresponding to the number of flexible drive rods. One end of each flexible drive rod rotates and is confined to the end joint of a flexible segment, while the other end, a smooth portion, passes sequentially through the remaining flexible segments. The flexible robotic arm and flexible robot of this invention can overcome the problems of driving force coupling and motion coupling between flexible segments, thereby achieving high-precision bending motion control.

Description

Technical Field

[0001] This invention relates to the field of flexible instruments, specifically to a flexible robotic arm and flexible robot that addresses the problems of non-driving force coupling and motion coupling between multiple flexible segments. Background Technology

[0002] Flexible robots, such as snake-like robots and continuum robots, are inspired by biomimicry, including snakes, elephant trunks, octopus tentacles, and vines. Compared to traditional rigid robots, flexible robot arms are composed of one or more flexible units connected by rigid joints. Flexible robots generate fully flexible motion through the deformation of these flexible units, theoretically possessing infinite degrees of freedom. Therefore, compared to rigid robots, flexible robots offer greater dexterity and safety.

[0003] In flexible robots, wire-driven or rod-driven methods are commonly used. These methods apply driving force to the tip of the flexible robot via a driving wire / rod, thereby generating dexterous bending motion and providing greater output force with a smaller size and longer transmission distance. Currently, these flexible robots are widely used in medical, industrial, and nuclear power plant inspection applications. However, the wire / rod driven method in multi-segment flexible robots presents problems of driving force coupling and motion coupling between flexible segments. Driving force coupling refers to the phenomenon where, when the distal segment of the robotic arm performs bending motion, the proximal segment is affected by the tension of the driving force of the distal segment, resulting in a corresponding deflection. Motion coupling refers to the fact that, because the driving wire of the distal segment must pass through the interior of the proximal segment, the bending shape of the distal segment changes accordingly when the proximal segment moves, and it cannot maintain its original bending shape.

[0004] Currently, to address the driving force coupling phenomenon between segments of multi-segment flexible robots, some researchers have proposed compensation models to actively compensate for the deflection caused by driving coupling, but this makes the control strategy extremely complex. Other researchers have taken a structural design approach, reducing coupling deflection by differentiating the stiffness of each segment or through special drive wire wiring designs, but these cannot completely eliminate driving force coupling. Furthermore, to solve the motion coupling problem, the drive motors of distal segments must adjust the drive wire length in real time according to the kinematic model; however, as the number of flexible segments in a flexible robot increases, the complexity of this control strategy rises sharply. Simultaneously, the elastic deformation and creep of the drive wire become significant over long scales, further exacerbating the difficulty of motion compensation.

[0005] Therefore, there is an urgent need to provide a multi-segment flexible robot that does not increase the complexity of motion control strategies or require complex structural design, while effectively overcoming the problems of inter-segment driving force coupling and motion coupling. Summary of the Invention

[0006] Based on the aforementioned defects and shortcomings of existing multi-segment flexible robots, the technical problem to be solved by the present invention is to provide a flexible manipulator and flexible robot that can overcome the problems of driving force coupling and motion coupling between flexible segments, thereby achieving high-precision bending motion control.

[0007] The technical solution adopted by this invention to solve the above-mentioned technical problem is: a multi-segment flexible robotic arm, comprising at least two interconnected flexible segments, each of which can perform bending motion under the antagonistic rotational drive of at least two flexible drive rods; wherein:

[0008] The flexible drive rod is provided with a threaded section;

[0009] The flexible segment includes an end joint, multiple channel joints, and multiple drive joints connected in series by at least two of the flexible drive rods; wherein:

[0010] Each of the aforementioned channel joints is provided with a channel through which at least two flexible drive rods can pass;

[0011] The plurality of drive joints are threadedly connected to at least two flexible drive rods through threaded connection holes of a number corresponding to the number of flexible drive rods;

[0012] One end of the flexible drive rod rotates and is confined to the end joint of the flexible segment, while the other end of the smooth rod passes through the remaining flexible segments in sequence.

[0013] Preferably, the flexible segment has two drive joints: a base drive joint located at the end of the flexible segment and a middle drive joint located in or near the middle of the flexible segment. Multiple channel joints are respectively located on both sides of the middle drive joint. The threaded segment on the flexible drive rod includes two interconnected variable-pitch threaded segments: the threaded segment matching the middle drive joint is the first threaded segment, and the threaded segment matching the base drive joint is the second threaded segment. The pitch ratio of the first threaded segment to the second threaded segment is equal to the ratio of the distance between the middle drive joint and the end joint to the distance between the base drive joint and the end joint, and the pitch of the first threaded segment should be less than the pitch of the second threaded segment.

[0014] Preferably, in the flexible segment, between any two adjacent joints, the tail end of the preceding joint is provided with an outwardly convex curved surface, and the head end of the following joint is provided with a groove that matches the curved surface, and the curved surface of the preceding joint abuts against the groove of the following joint.

[0015] Preferably, a central channel is provided at the central axis of each of the multiple flexible segments, and a steel wire flexible shaft is provided in the central channel. The steel wire flexible shaft is fixed to the two ends of each flexible segment.

[0016] Preferably, the central drive joint adopts a split structure, including a central joint, four semi-circular grooves evenly distributed in the circumferential direction of the central joint, and a fastening ring that connects and fixes the four semi-circular grooves to the central joint; four arc-shaped grooves are evenly distributed on the central joint, and threaded grooves are respectively provided on the semi-circular grooves; the threaded connection hole on the drive joint is formed by splicing the threaded grooves on the semi-circular grooves and the arc-shaped grooves provided on the central joint.

[0017] The present invention also provides a flexible robot, including the aforementioned flexible robotic arm, wherein the flexible drive rods in each flexible segment of the flexible robotic arm are respectively connected to corresponding follow-up drive devices, and the follow-up drive devices include a drive motor, a linear motion module, a synchronous belt drive device, and a synchronous belt drive shaft; wherein:

[0018] The drive motor and the synchronous belt transmission device are respectively fixed on the mounting bracket, and the mounting bracket is fixed on the linear motion module that can perform linear motion;

[0019] The power output end of the drive motor is connected to the drive pulley in the synchronous belt transmission device;

[0020] The synchronous belt drive shaft is connected to the driven pulley in the synchronous belt drive device, and the flexible drive rod is connected to the synchronous belt drive shaft.

[0021] Preferably, the flexible robotic arm includes three flexible segments with an overall columnar structure, namely a proximal flexible segment, an intermediate flexible segment, and a distal flexible segment connected in series; wherein: multiple flexible drive rods of the distal flexible segment pass through the joints of the intermediate flexible segment and the proximal flexible segment in sequence, and are respectively connected to the corresponding follow-up drive devices; multiple flexible drive rods of the intermediate flexible segment pass through the joints of the proximal flexible segment in sequence, and are respectively connected to the corresponding follow-up drive devices.

[0022] Preferably, the flexible robot further includes a drive base for fixing each follow-up drive device, wherein the proximal flexible segment is connected to the drive base and the diameter of the proximal flexible segment is larger than the diameter of the distal flexible segment.

[0023] Preferably, each of the flexible segments can achieve two degrees of freedom bending motion under the drive of four flexible drive rods.

[0024] Preferably, in the follow-up drive device, a first ferromagnetic screw is provided inside the synchronous belt drive shaft, and the flexible drive rod is connected to the synchronous belt drive shaft through a connecting shaft, with a second ferromagnetic screw threaded onto the connecting shaft; when the connecting shaft is assembled with the synchronous belt drive shaft, the first ferromagnetic screw and the second ferromagnetic screw achieve axial connection between the synchronous belt drive shaft and the flexible drive rod by relying on strong magnetic force.

[0025] Compared with the prior art, the present invention has the following advantages and effects:

[0026] 1. In the flexible robotic arm of the present invention, the flexible drive rod is provided with a threaded section. The joints of the flexible segment are divided into two types: one type is a drive joint with a threaded connection hole, whose thread is connected to the flexible drive rod; the other type is a channel joint without threads, which is provided with a channel around its perimeter for the flexible drive rod to pass through. The flexible drive rod achieves bending of the flexible segment by applying a pushing / pulling force to the end of the flexible segment. The reaction force of the end driving force is transmitted to the base drive joint of the flexible segment through the flexible drive rod, thereby achieving force balance of the flexible segment along the bending axis. Since the threaded flexible segment achieves bending motion through the antagonistic rotation of the relatively positioned flexible drive rod, and the threaded connection hole of the drive joint and the flexible drive rod in the relatively positioned position have the same structural parameters, it can be considered that the two antagonistically rotating flexible drive rods apply torques of equal magnitude and opposite direction to the flexible segment. The two torques cancel each other out, so that the flexible segment achieves a torque balance state. Therefore, the threaded flexible segment does not generate force or torque on other flexible segments during bending motion, thus achieving decoupling of driving force between segments.

[0027] 2. In the flexible robotic arm described in this invention, one end is defined as the distal flexible segment and the other end as the proximal flexible segment. The flexible drive rod of the distal flexible segment has one fixed end, while the other end, a smooth rod portion, passes through the channel of the proximal flexible segment. When the bending angle of the proximal flexible segment changes, the length of the drive rod within the proximal segment of the distal segment also changes accordingly. Due to the threaded self-locking characteristic between the flexible segment drive joint and the flexible drive rod, the distal flexible segment can maintain its original bending shape. In summary, motion decoupling between the flexible segments can be achieved.

[0028] 3. In the flexible robotic arm described in this invention, by simultaneously opening threaded connection holes on the base drive joint and the middle drive joint at the end, middle position, or near the middle position of the flexible segment, and by using a drive rod with a variable pitch threaded section to drive only the base drive joint and the middle drive joint at multiple points, the deflection angle between the middle drive joint and the end joint can be proportionally changed with the deflection angle between the base drive joint and the end joint, thereby achieving precise bending motion control and achieving a better bending deformation effect. At the same time, the self-locking characteristic of the thread restricts the relative movement between the drive joint and the flexible drive rod, thereby reducing the redundancy of the flexible segment to a certain extent and facilitating more accurate bending motion. In other words, the multi-point drive of the screw plays both a driving role and a limiting constraint role for the flexible segment.

[0029] 4. In the flexible robotic arm described in this invention, an elastic steel wire shaft runs through the central channel of multiple flexible segments. The inherent elasticity of the steel wire shaft makes the deflection angle between the joints more uniform when the flexible segments bend, which is beneficial to improving the accuracy of kinematic modeling based on the constant curvature assumption. At the same time, the steel wire shaft is fixed to the two ends of the flexible segments, and its high torsional stiffness can also limit the undesirable torsional movement of the flexible segments and improve their torsional resistance.

[0030] 5. In the flexible robotic arm described in this invention, the central drive joint adopts a separate structure, and the threaded connection hole of the central drive joint is formed by splicing the threaded groove on the semi-circular groove and the arc-shaped groove on the central joint. This arrangement can effectively avoid the problem of the base drive joint coming off when assembling the discrete joints of the flexible segment.

[0031] 6. In the flexible robot of the present invention, each of the flexible drive rods is connected to a corresponding follow-up drive device. In the follow-up drive device: the output end of the drive motor is connected to the synchronous belt transmission device, which is mounted on the linear motion module. When the drive motor starts, the flexible drive rod rotates by itself, which can drive the drive motor and the synchronous belt transmission device to move back and forth along the linear motion module. At the same time, since the flexible drive rod of the distal flexible segment passes through the channel of the proximal segment, the length of the drive rod of the distal segment in the proximal segment also changes accordingly with the change of the bending angle of the proximal flexible segment. The follow-up drive device allows the drive motor to move forward / backward under the pull / push of the flexible drive rod. Therefore, the drive motor can compensate for the coupled motion by passive movement without the need for active drive of the motor, thus effectively avoiding the application of traditional complex motion control strategies and making the bending motion control of each flexible segment in the multi-segment flexible robot simpler.

[0032] 7. The flexible robot described in this invention achieves excellent decoupling of driving force and motion between segments through the setting of threaded drive and follow-up drive devices (in the form of mechanical structure design); at the same time, the flexible drive rod with variable pitch drives multiple drive joints with threaded connection holes to perform multi-point drive, which reduces the redundancy of the flexible segments and makes the bending motion of the flexible segments more precise. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a three-dimensional structural diagram of the flexible robotic arm described in an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the flexible segmental three-dimensional structure described in an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the cross-sectional structure of the flexible segment described in an embodiment of the present invention.

[0037] Figure 4 This is a schematic diagram of the end joint portion structure according to an embodiment of the present invention.

[0038] Figure 5 This is an exploded view of the central drive joint structure described in an embodiment of the present invention.

[0039] Figure 6 , Figure 7 This is a schematic diagram of the channel joint in the flexible segment described in an embodiment of the present invention.

[0040] Figure 8 This is a schematic diagram of the two-degree-of-freedom bending state of a flexible segment in the flexible robotic arm described in an embodiment of the present invention.

[0041] Figure 9 This is a schematic diagram illustrating the force analysis of the flexible segment under bending conditions according to an embodiment of the present invention.

[0042] Figure 10 This is a schematic diagram of the overall structure of the flexible robot described in an embodiment of the present invention.

[0043] Figure 11 This is a schematic diagram of the split structure of the flexible robot drive device according to an embodiment of the present invention.

[0044] Figure 12 This is an exploded view of the follow-up drive device structure according to an embodiment of the present invention.

[0045] Labeling Explanation: 1. Flexible Segment; 11. Base Drive Joint; 12. Middle Drive Joint; 121. Middle Joint; 122. Arc-shaped Groove; 123. Semicircular Groove; 124. Threaded Groove; 125. Fastening Ring; 13. Channel Joint; 131. Joint Channel; 132. Groove; 133. Curved Surface; 14. End Joint; 141. Joint Body; 142. Joint End Cap; 143. Miniature Bearing; 144. Copper Sleeve; 145. Fastening Screw; 2 1. Flexible drive rod; 21. Threaded section; 211. First threaded section; 212. Second threaded section; 3. Steel wire flexible shaft; 4. Follow-up drive device; 41. Drive motor; 42. Synchronous belt drive device; 43. Synchronous belt fixing bracket; 44. Mounting bracket; 45. Synchronous belt drive shaft; 46. Connecting shaft; 47. First ferromagnetic screw; 48. Linear guide rail; 49. Slider; 5. Connecting seat; 6. Base; 7. Rear end cover; 8. Front end cover; 9. Mounting base plate. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to the embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0047] Example 1: As Figure 1 As shown, this embodiment provides a multi-segment flexible robotic arm, including at least two interconnected flexible segments 1, each of which can perform bending motion under the antagonistic rotational drive of at least two flexible drive rods 2; wherein:

[0048] like Figure 2 , 3 As shown, the flexible drive rod 2 is provided with a threaded section 21; the flexible segment 1 includes an end joint 14, a plurality of channel joints 13, and a plurality of drive joints, which are connected in series by at least two of the flexible drive rods 2; wherein:

[0049] The distal joint 14 is located at the end of the flexible segment 1;

[0050] Each of the multiple channel joints 13 is provided with a channel 131 through which at least two flexible drive rods 2 can pass;

[0051] The plurality of drive joints are threadedly connected to at least two flexible drive rods 2 through threaded connection holes of a number corresponding to the number of flexible drive rods;

[0052] One end of each of the flexible drive rods 2 rotates and is confined to the end joint 14 of the flexible segment 1, while the other end of the rod passes through the remaining flexible segments 1 in sequence.

[0053] like Figure 1 , 3As shown, in the flexible robotic arm described in this embodiment, at least two flexible segments 1 are connected in series mainly through the smooth rod portions of multiple flexible drive rods 2; wherein, "smooth rod" is interpreted as the non-threaded section portion on the flexible drive rod 2;

[0054] like Figure 3 , 4 As shown, the fact that one end of the flexible drive rod 2 rotates and is confined to the end joint 14 means that the flexible drive rod 2 is rotatably mounted on the end joint 14, and will not disengage from the end joint 14 during rotation; specifically, the flexible drive rod 2 and the end joint 14 are connected and installed in the following manner:

[0055] The end joint 14 is composed of a joint body 141 and a joint end cap 142, which are fixed by a plurality of fastening screws 145. Miniature bearings 143 for assembling flexible drive rod 2 are respectively embedded in the joint body 141 and the joint end cap 142. The end of the flexible drive rod 2 passes through two miniature bearings 143 disposed on the joint body 141 and the joint end cap 142, and a copper sleeve 144 is provided between the two miniature bearings 143 to axially limit the flexible drive rod 2. The copper sleeve 144 is clamped and fixed on the flexible drive rod 2.

[0056] The multi-segment flexible robotic arm designed in Embodiment 1 of this invention can effectively avoid the problems of driving force coupling and motion coupling between multiple flexible segments 1. The basic principle is as follows:

[0057] In traditional wire-driven flexible robots, a driving force along the axial direction of the driving wire is applied to the end of a flexible segment, causing the flexible segment to bend. In contrast, the flexible robotic arm described in this invention uses a lever-driven method, wherein: as... Figure 9 As shown, due to the characteristic of threaded transmission that it can convert input torque into axial output force, the flexible drive rod 2 applies an axial force F acting on the end of the flexible segment 1. e In addition, a counterforce F is applied through the threaded connection hole of the drive joint. b Meanwhile, due to the thread self-locking effect, the threaded connection hole of the drive joint and the threaded section of the drive rod will not be separated due to axial force F. e This generates relative movement, meaning that the axial force F applied by the flexible drive rod 2 to the threaded connection hole of the drive joint... b The size is always related to F e Equal, i.e., F e =-F bOn the other hand, because the threaded flexible segment achieves bending motion by lengthening or shortening the distance between the drive joint and the end joint through the antagonistic rotation of two relatively positioned flexible drive rods, the threaded connection hole of the drive joint and the flexible drive rods in the relatively positioned position have the same structural parameters. Therefore, it can be considered that the two antagonistically rotating drive rods apply torques of equal magnitude and opposite direction to the flexible segment, and the two torques cancel each other out, so that the flexible segment reaches a torque balance state. Therefore, the threaded flexible segment does not generate force or torque on other series-connected flexible segments during bending motion, thereby achieving decoupling of the driving force between the segments.

[0058] At the same time, such as Figure 1 As shown, in the flexible robotic arm of this invention, one end is defined as the distal flexible segment and the other end as the proximal flexible segment. The flexible drive rod of the distal flexible segment passes through the channel of the proximal flexible segment. Furthermore, as the bending angle of the proximal flexible segment changes, the length of the drive rod within the proximal segment also changes accordingly. Due to the threaded self-locking characteristic between the flexible segment drive joint and the flexible drive rod, the distal flexible segment maintains its original bending shape. In summary, motion decoupling between the flexible segments can be achieved.

[0059] Example 2: The flexible segment 1 of the present invention has a drive joint with a threaded connection hole. The thread engages with the flexible drive rod to drive the flexible segment in bending motion. A schematic diagram of the flexible segment's state is shown in Figure 8. In this example, to ensure good bending deformation of the flexible segment, the following limitations are made regarding the threaded section on the flexible drive rod 2 and the drive joint in the flexible segment 1:

[0060] like Figure 2 As shown, in one embodiment, the flexible segment 1 in this embodiment has two drive joints, namely a base drive joint 11 located at the end of the flexible segment 1 and a middle drive joint 12 located in or near the middle of the flexible segment 1. The plurality of channel joints 13 are respectively arranged on both sides of the middle drive joint 12.

[0061] The number of channel joints 13 can be arbitrarily set according to the design requirements such as the size and range of motion of the flexible robot, without strict limitations; the central drive joint 12 can be set in the middle of the flexible segment 1 or near the middle of the flexible segment 1; here, "near" is interpreted as a distance of 0.5-1 channel joint heights away from the middle position.

[0062] Furthermore, such as Figure 3As shown, the threaded segment 21 on the flexible drive rod 2 is composed of two interconnected variable pitch threaded segments. By driving the two variable pitch flexible drive rods 2 in opposite positions to perform antagonistic torsional motion, the distance between the base drive joint 11, the middle drive joint 12 and the end joint 14 can be shortened / extended, thereby causing the flexible segment to bend. Among them, on the flexible drive rod 2, the threaded segment matching the middle drive joint 12 is the first threaded segment 211, and the threaded segment matching the base drive joint 11 is the second threaded segment 212. The pitch ratio of the first threaded segment 211 to the second threaded segment 212 is equal to the ratio of the distance between the middle drive joint and the end joint to the distance between the base drive joint and the end joint, and the pitch of the first threaded segment should be less than the pitch of the second threaded segment.

[0063] The specific reasons and advantages for using the above-described configuration in the flexible segment of this embodiment are as follows:

[0064] (1) Typically, flexible robots are underactuated robots, whose joint bodies can undergo relative displacement with respect to the drive screw / rod, which is the source of their flexibility. However, the friction between the drive screw / rod and the joint body, as well as the influence of other external forces, can lead to inaccurate motion. In this embodiment, by setting drive joints at the ends and middle of the flexible segment 1 and opening threaded connection holes on the drive joints, and driving the relatively set variable pitch screws to drive the base drive joint 11 and the middle drive joint 12 at multiple points, the deflection angle θ1 between the middle drive joint 12 and the end joint 14 can be proportionally changed with the deflection angle θ2 between the base drive joint 11 and the end joint 14, thereby achieving precise bending motion control and achieving a better bending deformation effect. At the same time, the self-locking characteristic of the thread restricts the relative motion between the drive joint and the flexible drive rod, thereby reducing the redundancy of the flexible segment to a certain extent. In other words, the multi-point drive of the screw plays both a driving role and a limiting constraint role for the flexible segment, thus making the robot's bending motion more precise.

[0065] (2) In the flexible robotic arm described in this application, the bending motion of the flexible segment 1 is generated by the change in the length between the drive joint and the end joint, and the rotation of the flexible drive rod 2 is essentially to change its drive length; in the motion control of the flexible segment 1, such as Figure 8As shown, it is generally assumed that the flexible segment bends into a uniform arc (constant curvature assumption), with an arc radius of R, an arc length of L, and a distribution radius of the drive rod from the center of the flexible segment of r. The corresponding change in screw drive length is then (L / R)*r. Clearly, the distance between the middle drive joint 12 and the end joint 14 (corresponding to arc length L1) is different from the distance between the base drive joint 11 and the end joint 14 (corresponding to arc length L2). Therefore, when the flexible segment 1 bends, the changes in screw drive length at the middle drive joint 12 and the base drive joint 11 are also different, with a ratio of L1 / L2. Since both the middle drive joint 12 and the base drive joint 11 are driven by the same flexible drive rod, threaded segments with different pitches need to be set on the flexible drive rod 2. The pitch ratio of the different threaded segments is determined by the distance between the drive joint and the end joint.

[0066] Specifically, such as Figure 3 As shown, in this embodiment, the flexible drive rod 2 is made by adhering a customized variable pitch spring (the first threaded section 211 has a pitch of 1.2 mm, and the second threaded section 212 has a pitch of 2.2 mm) to the outer layer of a steel wire flexible shaft (outer diameter = 2 mm) with an adhesive.

[0067] Example 3: , as Figure 3 As shown, in this embodiment, five channel joints are provided between the middle driving joint 12 and the end joint 14, and four channel joints are provided between the base driving joint 11 and the middle driving joint 12. The flexible segment 1 is composed of 12 discrete joints. In order to further improve the bending motion capability of the flexible segment, as a preferred embodiment, the discrete joints in the flexible segment 1 can be interconnected in the following ways:

[0068] Between any two adjacent joints, the tail end of the preceding joint has an outwardly convex curved surface (e.g., ...). Figure 7 As shown, the tail end of the channel joint 13 is provided with an outwardly protruding curved surface 133, and the head end of the subsequent joint is provided with a groove that matches the curved surface (e.g., as shown). Figure 6 As shown, the first end of the channel joint 13 is provided with a groove 132 that matches the curved surface 133, and the curved surface of the first joint abuts against the groove of the second joint.

[0069] like Figure 3 As shown, this configuration allows for the formation of ball-and-socket joints that enable relative rotation between any adjacent joints. It features a simple structure and allows for two degrees of freedom of deflection between joints. In contrast, other types of discrete joints typically have more complex structural designs, such as universal joints and gear-meshing joints, which only allow one degree of freedom of deflection between joints, thus limiting bending motion capabilities.

[0070] Example 4: In the flexible robotic arm described in Examples 1 to 3 of the present invention, the assembly sequence of the flexible segment 1 is as follows: each flexible drive rod 2 is screwed into the threaded connection hole of the base drive joint 11, multiple channel joints 13 are fitted onto the flexible drive rod 2, the middle drive joint 12 is installed, and then the remaining channel joints 13 and the end joint 14 are installed; wherein: when installing the middle drive joint 12, due to the limitation of the screw thread, if the middle drive joint 12 adopts an integrated design, when the drive rod screw is screwed into the middle drive joint, it will be found that the base drive joint also moves relative to the screw and eventually disengages; therefore, to avoid this assembly problem:

[0071] like Figure 5 As shown, in this embodiment, the central drive joint 12 is designed as a split structure, including a central joint 121, four semi-circular grooves 123 evenly distributed in the circumferential direction of the central joint 121, and a fastening ring 125 that connects and fixes the four semi-circular grooves 123 to the central joint 121; wherein: four arc-shaped grooves 122 are evenly distributed on the central joint 121, and threaded grooves 124 are respectively provided on the semi-circular grooves 123; the threaded connection hole of the drive joint is formed by splicing the threaded grooves 124 on the semi-circular grooves 123 and the arc-shaped grooves 122 on the central joint 121; this split structure design can effectively avoid the assembly interference problem that exists when the threaded connection holes of multiple drive joints and the threads of the flexible drive rod are simultaneously engaged.

[0072] Example 5: Figures 1 to 3 As shown, this embodiment provides a flexible robotic arm. The difference from embodiments 1 to 4 is that a central channel is opened at the central axis of each of the multiple flexible segments 1, and a steel wire flexible shaft 3 is provided in the central channel. The steel wire flexible shaft 3 is fixed to the two ends of each flexible segment 1.

[0073] In the flexible robotic arm described in this embodiment, a flexible steel wire shaft runs through the central channel of each of the multiple flexible segments 1. The inherent elasticity of the steel wire shaft makes the deflection angle between the joints more uniform when the flexible segments bend, which helps to improve the accuracy of kinematic modeling based on the constant curvature assumption. At the same time, the steel wire shaft 3 is fixed to the two ends of the flexible segments 1, and its high torsional stiffness can also limit the undesirable torsional movement of the flexible segments and improve their torsional resistance.

[0074] Example 6: As Figures 10 to 12 As shown, this embodiment provides a flexible robot, which includes a flexible robotic arm as described in any of embodiments 1 to 5. Multiple flexible drive rods 2 within each flexible segment 1 of the flexible robotic arm are respectively connected to corresponding follow-up drive devices 4; as shown... Figure 12As shown, the follow-up drive device 4 includes a drive motor 41, a linear motion module, a synchronous belt drive device 42, and a synchronous belt drive shaft 45; wherein:

[0075] The drive motor 41 is fixed on the mounting bracket 44, and the power output end of the motor is connected to the drive pulley in the synchronous belt transmission device 42.

[0076] The synchronous belt drive device 42 is fixed on the mounting bracket 44 by the synchronous belt fixing frame 43, and the mounting bracket 44 is fixed on the linear motion module that can perform linear displacement.

[0077] The synchronous belt drive shaft 45 is connected to the driven wheel in the synchronous belt drive device 42, and the flexible drive rod 2 is connected to the synchronous belt drive shaft 45.

[0078] Among them: such as Figure 12 As shown, the linear motion module includes a linear guide rail 48 and a slider 49 slidably mounted on the linear guide rail, and the mounting bracket 44 is fixed on the slider 49.

[0079] In the flexible robot described in this embodiment, the follower drive device 4 can drive the flexible drive rod to rotate and generate linear displacement. The specific working principle is as follows:

[0080] In the synchronous belt drive device 42, the lower part is the driving pulley and the upper part is the driven pulley. When the drive motor 41 starts, the driving pulley rotates and drives the driven pulley to rotate through the synchronous belt. This, in turn, drives the synchronous belt drive shaft 45 fixed on the driven pulley and the flexible drive rod 2 connected to the synchronous belt drive shaft 45 to rotate. The flexible drive rod 2 drives the synchronous belt drive device 42 and the drive motor 41 fixed to the mounting bracket 44 to move linearly along the linear guide rail 48 through its own rotational movement.

[0081] In the flexible robotic arm of the flexible robot described in this embodiment, one end is defined as the distal flexible segment and the other end as the proximal flexible segment. Since the flexible drive rod in the distal flexible segment passes through the channel of the proximal flexible segment, the length of the drive rod in the proximal segment changes accordingly with the change of the bending angle of the proximal flexible segment. The follow-up drive device allows the drive motor 41 to move forward / backward under the pull / push of the flexible drive rod. Therefore, the drive motor can compensate for the coupled motion by passive movement without the need for active drive of the motor, thus effectively avoiding the application of traditional complex motion control strategies. In addition, due to the thread self-locking characteristic between the flexible drive rod and the drive joint, the distal flexible segment will maintain its original bending shape, thus avoiding motion coupling between flexible segments.

[0082] Example 7: As Figures 10 to 12As shown, this embodiment, based on the flexible robot described in Embodiment 6, further defines the following:

[0083] like Figure 10 As shown, the flexible robotic arm includes three flexible segments 1 with an overall columnar structure, namely a proximal flexible segment, a middle flexible segment, and a distal flexible segment connected in series.

[0084] Specifically: multiple flexible drive rods of the distal flexible segment pass through the joint interiors of the intermediate flexible segment and the proximal flexible segment in sequence, and are respectively connected to the corresponding follow-up drive devices; multiple flexible drive rods of the intermediate flexible segment pass through the joint interiors of the proximal flexible segment in sequence, and are respectively connected to the corresponding follow-up drive devices.

[0085] In this invention, there is no strict limitation on the number of flexible segments. However, the driving force coupling and motion coupling problems that this application needs to solve are common in multi-segment (two or more segments) flexible robots. The more flexible segments a flexible robot has, the higher its dexterity. This embodiment takes a three-segment flexible robot with interconnected proximal flexible segments, intermediate flexible segments and distal flexible segments as an example, which can realize full-degree-of-freedom (six-degree-of-freedom) motion in space.

[0086] In this embodiment, from the perspective of flexible robot structural design, the larger the diameter of the flexible segment, the greater its stiffness and the better its load-bearing capacity. The proximal flexible segment near the robot connector needs to withstand the gravity from the flexible segment near the robot's end (far end), which affects the overall motion accuracy of the flexible robot. Therefore, the proximal flexible segment has a design requirement for higher load-bearing capacity, necessitating an increased diameter. Simultaneously, the smaller design size of the far flexible segment helps reduce its weight and further mitigates the impact of the far flexible segment's gravity on the flexible robot's motion accuracy. Therefore, in this embodiment, preferably, the diameter of the proximal flexible segment can be set larger than that of the far flexible segment, satisfying both the high load-bearing capacity requirement at the proximal end and improving the motion accuracy at the far end. Specifically, the far flexible segment (132mm long, 20mm diameter), the intermediate flexible segment (132mm long, 22mm diameter), and the proximal flexible segment (132mm long, 24mm diameter) have different diameters but the same structural design.

[0087] Furthermore, as one implementation method, each flexible segment of the flexible robotic arm described in this embodiment can achieve two-degree-of-freedom bending motion under the drive of four flexible drive rods 2.

[0088] Among them: the four flexible drive rods 2 are grouped in pairs, and the two drive rods in each group control the bending degree of freedom of the flexible segment in one direction through antagonistic rotational motion. The bending state diagram is shown below. Figure 8As shown. Correspondingly, as Figure 11 As shown, in the flexible robot described in this embodiment, since each flexible segment is driven by four flexible drive rods, the total number of flexible drive rods located in the proximal flexible segment is 12. The 12 flexible drive rods are respectively connected to 12 follower drive devices. The 12 follower drive devices can be evenly distributed along the circumferential direction and are respectively fixed to the drive base of the flexible robot through the mounting base plate 9. The drive base consists of a front end cover 8, a rear end cover 7 connected to several mounting base plates 9, and a base 6 connected to one of the mounting base plates 9. In this embodiment, the flexible robotic arm is mounted on the front end cover 8 through the connecting seat 5.

[0089] Example 8: As Figures 10 to 12 As shown, this embodiment provides another preferred implementation method based on the flexible robot described in Embodiment 7:

[0090] like Figure 12 As shown, in the follow-up drive device 4, a first ferromagnetic screw 47 is provided inside the synchronous belt drive shaft 45. The flexible drive rod 2 is connected to the synchronous belt drive shaft 45 through a connecting shaft 46, and a second ferromagnetic screw is threaded onto the connecting shaft 46. When the connecting shaft 46 is assembled with the synchronous belt drive shaft 45, the first ferromagnetic screw 47 and the second ferromagnetic screw achieve axial connection between the synchronous belt drive shaft 45 and the flexible drive rod 2 by relying on strong magnetic force. This magnetic connection method can realize the quick assembly and disassembly between each flexible drive rod 2 and the follow-up drive device 4 in the multi-segment flexible robotic arm, thereby reducing assembly difficulty and assembly time.

[0091] Example 9: This example mainly verifies the relevant performance of the flexible robot described in this invention through the following experiments;

[0092] (1) End-positioning error test (bending performance)

[0093] Experimental method: An optical marker ball was fixed on the end joint of the flexible segment. The flexible segment was driven by a motor to reciprocate within a range of ±90°. The difference between the actual position of the optical marker ball measured by the optical sensor and the theoretical position of the kinematic model was compared. The results showed that the average positioning error of the flexible segment driven by the variable pitch thread in constant curvature bending motion was 1.97 mm, accounting for 1.44% of its total length (132 mm), and the maximum positioning error was 4.78 mm (accounting for 3.49% of its total length).

[0094] Secondly, through a spatial multi-point positioning accuracy evaluation experiment, 120 designated target points were given in three-dimensional space. After solving the inverse kinematics, the motor drive quantity was obtained, which drove the multi-segment flexible manipulator to move in three-dimensional space. The difference between the actual end position and the target position was compared. The experiment was repeated three times and the average error was calculated. The results showed that the average positioning error of the flexible manipulator described in this embodiment was 14.59 mm, accounting for 3.68% of the total length (496 mm). This indicates that the flexible manipulator described in this invention can achieve precise bending motion control and achieve a good bending deformation effect.

[0095] (2) Driving force decoupling performance experiment

[0096] This invention presents a driving force decoupling performance experiment on a three-segment thread-driven flexible robot to briefly demonstrate its driving force decoupling capability.

[0097] Specifically, by driving the proximal flexible segment to bend to a certain angle and then keeping it stationary, and then driving the distal segment to perform reciprocating bending motion, the results are tracked and sampled in real time. The results show that the position change of the proximal segment end is less than 0.76 mm and the bending angle change is less than 0.29°. It can be concluded that the flexible robot described in this invention achieves excellent decoupling of driving forces between segments.

[0098] (3) Motion decoupling experiment

[0099] This invention conducted motion decoupling performance experiments on a three-segment thread-driven flexible robot. By driving the distal segment to bend to a certain angle and keeping it stationary, and then driving the proximal segment to perform reciprocating bending motion, real-time tracking and sampling results showed that the bending angle change of the distal flexible segment was less than 0.63°. The experimental results indicate that the flexible robot described in this invention achieves excellent motion decoupling between segments.

[0100] In summary, the flexible robot provided by this invention achieves excellent decoupling of driving force and motion between the segments of the flexible robot through a mechanical structure design using threaded drive and follower drive devices. At the same time, the novel variable pitch threaded drive reduces the redundancy of the flexible robot by driving multiple threaded joints with a variable pitch flexible screw, making the robot's bending motion more precise.

[0101] Furthermore, it should be noted that the shapes and names of the parts and components described in the specific embodiments described in this specification may differ. All equivalent or simple variations made to the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the structure of this invention or exceed the scope defined in these claims, they should all fall within the protection scope of this invention.

Claims

1. A multi-section flexible robotic arm, characterized by, It includes at least two interconnected flexible segments, each of which can perform bending motion under the antagonistic rotational drive of at least two flexible drive rods; wherein: The flexible drive rod is provided with a threaded section; The flexible segment includes an end joint, multiple channel joints, and multiple drive joints connected in series by at least two of the flexible drive rods; wherein: Each of the aforementioned channel joints is provided with a channel through which at least two flexible drive rods can pass; The plurality of drive joints are threadedly connected to at least two flexible drive rods through threaded connection holes of a number corresponding to the number of flexible drive rods; One end of the flexible drive rod rotates and is confined to the end joint of the flexible segment, while the other end, a smooth rod portion, passes sequentially through the remaining flexible segments; additionally, The flexible segment has two drive joints: a base drive joint located at the end of the flexible segment and a middle drive joint located in or near the middle of the flexible segment. Multiple channel joints are respectively located on both sides of the middle drive joint. The threaded segment on the flexible drive rod includes two interconnected variable pitch threaded segments: the threaded segment matching the middle drive joint is the first threaded segment, and the threaded segment matching the base drive joint is the second threaded segment. The pitch ratio of the first threaded segment to the second threaded segment is equal to the ratio of the distance between the middle drive joint and the end joint to the distance between the base drive joint and the end joint, and the pitch of the first threaded segment is less than the pitch of the second threaded segment.

2. The flexible manipulator of claim 1, wherein, In the flexible segment, between any two adjacent joints, the tail end of the preceding joint is provided with an outwardly convex curved surface, and the head end of the following joint is provided with a groove that matches the curved surface. The curved surface of the preceding joint and the groove of the following joint abut against each other.

3. The flexible manipulator arm of claim 1 or 2, wherein, Each of the flexible segments has a central channel at its central axis, and a steel wire flexible shaft is installed in the central channel. The steel wire flexible shaft is fixed to the two ends of each flexible segment.

4. The flexible robotic arm of claim 3, wherein, The central drive joint adopts a split structure, including a central joint, four semi-circular grooves evenly distributed in the circumferential direction of the central joint, and a fastening ring that connects and fixes the four semi-circular grooves to the central joint; four arc-shaped grooves are evenly distributed on the central joint, and threaded grooves are respectively provided on the semi-circular grooves; the threaded connection hole on the drive joint is formed by splicing the threaded grooves on the semi-circular grooves and the arc-shaped grooves provided on the central joint.

5. A flexible robot, characterized in that, The flexible robotic arm includes any one of claims 1 to 4, wherein the flexible drive rods in each flexible segment of the flexible robotic arm are respectively connected to corresponding follow-up drive devices, and the follow-up drive device includes a drive motor, a linear motion module, a synchronous belt drive device, and a synchronous belt drive shaft; wherein: The drive motor and the synchronous belt transmission device are respectively fixed on the mounting bracket, and the mounting bracket is fixed on the linear motion module capable of linear motion; The power output end of the drive motor is connected to the drive pulley in the synchronous belt transmission device; The synchronous belt drive shaft is connected to the driven pulley in the synchronous belt drive device, and the flexible drive rod is connected to the synchronous belt drive shaft.

6. The flexible robot of claim 5, wherein, The flexible robotic arm comprises three flexible segments with an overall columnar structure: a proximal flexible segment, an intermediate flexible segment, and a distal flexible segment connected in series. Multiple flexible drive rods of the distal flexible segment pass sequentially through the joints of the intermediate and proximal flexible segments and are connected to corresponding follow-up drive devices. Similarly, multiple flexible drive rods of the intermediate flexible segment pass sequentially through the joints of the proximal flexible segment and are connected to corresponding follow-up drive devices.

7. The flexible robot of claim 6, wherein, The flexible robot also includes a drive base for fixing each follow-up drive device, the proximal flexible segment is connected to the drive base, and the diameter of the proximal flexible segment is larger than the diameter of the distal flexible segment.

8. The flexible robot of claim 6, wherein, Each of the flexible segments can achieve two degrees of freedom bending motion under the drive of four flexible drive rods.

9. The flexible robot of claim 8, wherein, In the follow-up drive device, a first ferromagnetic screw is provided inside the synchronous belt drive shaft, and the flexible drive rod is connected to the synchronous belt drive shaft through a connecting shaft. A second ferromagnetic screw is threaded onto the connecting shaft. When the connecting shaft and the synchronous belt drive shaft are assembled, the first ferromagnetic screw and the second ferromagnetic screw achieve axial connection between the synchronous belt drive shaft and the flexible drive rod by relying on strong magnetic force.

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