A repeatable locking mechanism based on disc spring unstable switching and its working method

Abstract

This invention discloses a repeatable locking mechanism based on disc spring unstable switching, including a support housing, a spindle, a motor assembly, a screw, a slider, a nut slider, a conical coil spring, a disc spring, and a self-locking mechanism. The invention also discloses a method for operating the above-mentioned repeatable locking mechanism, including: the motor assembly driving the spindle to rotate; the slider moving to a first driving position engaging with the upper screw, the spindle driving the upper screw to rotate via the slider; the upper screw driving the upper nut slider to move up and down, locking or unlocking the self-locking mechanism A; the upper screw driving the upper nut slider to continue moving downwards, after the conical coil spring undergoes torsional deformation, the nut slider pushes the slider downwards, causing the slider to move to a second driving position engaging with the lower screw, the spindle driving the lower screw to rotate via the slider. This invention enables selective locking and further improves the stiffness of the flexible arm.

Description

Technical Field

[0001] This invention relates to a repeatable locking mechanism based on disc spring unstable switching and its working method, belonging to the field of robotics technology. Background Technology

[0002] Robotics has a long history of application, especially with the rapid development of information and control technologies in recent decades. Robotics has grown rapidly, extending from traditional industrial applications to everyday life; from ground applications to marine and space applications; and from rigid robots to continuous biomimetic robots. In short, replacing, enhancing, and expanding certain functions of intelligent organisms like humans through robots will become an inevitable trend in social development. Rigid robots, such as rigid serial manipulators and rigid parallel mechanisms, have been extensively studied and widely used, but their flexibility and adaptability are insufficient. With the deepening of bionics research and a better understanding of the functional advantages of certain biological systems, biomimetic robots have emerged.

[0003] Current space robots are primarily based on rigid robotic arms. The microgravity environment of space poses significant risks to operations such as capturing non-cooperative targets, demanding high precision and adaptability from robotic arms. While the design and control technology of traditional rigid articulated robotic arms are mature, they lack sufficient compliance and flexibility, resulting in low environmental adaptability. Deviations between the probe's attitude control and the robotic arm's operational control can lead to capture failures or even damage to the probe. Therefore, there is an urgent need to develop new robotic arms with multi-degree-of-freedom motion capabilities and operational compliance to reduce control precision requirements, prevent collision damage to spacecraft, and improve operational success rates. Continuum robots, with their flexible deformability, can ensure the safety and robustness of capture operations, meeting the needs of space probe capture, docking, berthing, parts twisting, insertion, removal, refueling, maintenance, space debris removal, and enemy satellite capture and destruction. They possess unique advantages in space station construction and space governance.

[0004] Continuum robots are designed to mimic the flexible biological structures of snakes, elephant trunks, octopuses, and other similar organisms. They primarily achieve bending and deformation motion through the expansion and contraction of their elastic structures. Compared to traditional rigid articulated industrial robots, the flexible structure and underactuated nature of continuum robots give them excellent adaptability and compliance. Their adaptive bending capability allows them to operate in unstructured environments, including confined spaces and areas with numerous obstacles. Their compliance ensures excellent safety when interacting with objects and the environment.

[0005] Continuum robots have achieved excellent environmental adaptability and safety, but at the cost of system stiffness and operational accuracy. Therefore, designing robots that possess both flexible adaptive capabilities to ensure safe and smooth interaction with the environment during motion, and high load-bearing capacity and end-effector accuracy remains a challenge. Biomimetic dexterous mechanism design techniques and repeatable variable stiffness mechanism design methods hold promise for resolving these contradictions and improving the applicability of continuum robots.

[0006] There is currently a lot of research on reusable locking mechanisms, mainly including mechanical, shape memory alloy, and electromagnetic types. These generally directly drive the locking mechanism, which is inconvenient for multi-stage transmission. Among them, mechanical locking mechanisms such as hook type, claw type, and bolt-nut type locking methods basically use one motor to control one degree of freedom. This method only locks a single degree of freedom and does not have selective locking function. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned defects and provide a repeatable locking mechanism based on disc spring unstable switching and its working method. This invention solves the technical problem that traditional repeatable locking mechanisms do not have selective locking function. This invention can perform selective locking and further improve the stiffness of the flexible arm.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A repeatable locking mechanism based on disc spring unstable switching includes a support housing, a spindle, a motor assembly, a screw, a slider, a nut slider, a conical coil spring, a disc spring, and a self-locking mechanism;

[0010] The spindle is located inside the support housing, with its upper and lower ends mounted on the top and bottom of the support housing, respectively; the motor assembly is used to drive the spindle to rotate.

[0011] The mandrel is divided into an upper section, a middle section and a lower section. Two screws are respectively located on the outside of the upper section and the lower section of the mandrel. The two screws are referred to as the upper screw and the lower screw.

[0012] The middle section of the mandrel is provided with a first slide rail in the vertical direction. The first protrusion provided on the inner side of the slider is embedded in the first slide rail. When the slider moves along the mandrel to the first driving position that cooperates with the upper screw, the mandrel drives the upper screw to rotate through the slider. When the slider moves along the mandrel to the second driving position that cooperates with the lower screw, the mandrel drives the lower screw to rotate through the slider.

[0013] The two nut sliders are referred to as the upper nut slider and the lower nut slider, respectively. The upper nut slider and the lower nut slider are installed on the outside of the upper screw and the lower screw, respectively. The rotation of the screw drives the nut sliders to move up and down along the screw. The up and down movement of the upper nut slider and the lower nut slider are used to lock or unlock two different self-locking mechanisms, respectively.

[0014] The screw has a first boss at its end. A conical coil spring is sleeved on the outside of the screw and located between the first boss and the nut slider. The conical coil spring is used to generate torsional deformation under the action of the nut slider and to realize the reset of the nut slider after the nut slider stops moving. The slider moves along the spindle under the push of the nut slider.

[0015] The inner edge of the disc spring is connected to the outer side of the middle section of the spindle, and the outer edge of the disc spring is connected to the inner side of the slider. The up and down movement of the slider drives the outer edge of the disc spring to move relative to the inner edge of the disc spring, realizing the switching between the first steady state and the second steady state of the disc spring. The disc spring in the first steady state and the second steady state are used to realize the positioning of the slider in the first driving position and the second driving position, respectively.

[0016] Furthermore, the self-locking mechanism includes a mounting ring, a bearing housing, and a slotted bearing;

[0017] There are two bearing housings, referred to as the upper bearing housing and the lower bearing housing; there are two slotted bearings, referred to as the upper slotted bearing and the lower slotted bearing.

[0018] The first ends of several locking springs are respectively installed in several radial grooves opened on the upper surface of the mounting ring, and the second ends are fixedly connected to the upper bearing seat, and the upper slotted bearing is installed on the upper bearing seat; the lower bearing seat is installed on the lower surface of the mounting ring, and the lower slotted bearing is installed on the lower bearing seat.

[0019] The first end of the upper or lower rope is simultaneously wound around the upper slotted bearing and the lower slotted bearing, and the second end is fixedly connected to the locking spring. The upper or lower rope passes through the upper nut slider or the lower nut slider respectively and is fixedly connected to the upper nut slider or the lower nut slider at that point. The part between the first end of the upper or lower rope and the fixed connection point is called the locking drive section, and the part between the second end of the upper or lower rope and the fixed connection point is called the unlocking drive section.

[0020] The mounting ring has a first through hole, the first end of the locking spring has a second through hole, one end of the steel bar or rope is connected to the flexible arm drive motor, and the other end passes through the first through hole and the second through hole in sequence to connect to the end of the flexible arm.

[0021] When the locking drive section retracts, the upper slotted bearing presses down the second end of the locking spring through the upper bearing seat, causing the first end of the locking spring to slide outward along the radial groove, pressing the steel bar or rope against the upper surface of the mounting ring. Locking is achieved through the friction between the steel bar or rope, the upper surface of the mounting ring, and the locking spring.

[0022] When the unlocking drive section retracts, it pulls the locking spring to reset, and the first through hole, the second through hole, and the steel bar or rope become coaxial, thus unlocking the device.

[0023] Furthermore, the inner wall of the support housing is provided with a second slide rail in the vertical direction;

[0024] The inner side of the nut slider is threaded to the outer side of the screw, and the outer side of the nut slider is engaged with the second slide rail provided on the inner wall of the support housing. When the screw rotates, the movement of the nut slider is limited by the second slide rail.

[0025] Furthermore, a first groove is provided on the first protrusion of the screw, one end of the conical coil spring is fixedly connected to the nut slider, and the other end of the conical coil spring is provided with a pin. The movement of the nut slider drives the other end of the conical coil spring to cooperate with the first groove through the pin. The continued movement of the nut slider causes the conical coil spring to undergo torsional deformation.

[0026] A second groove matching the slider is formed on the first boss of the screw;

[0027] When the slider moves to the first drive position or the second drive position, the slider is embedded in the second groove to cooperate with the screw;

[0028] When the disc spring is in the first stable state, the outer edge of the disc spring is above the inner edge. When the disc spring is in the second stable state, the outer edge of the disc spring is below the inner edge.

[0029] Furthermore, the support housing includes a support cover and a support base;

[0030] The support cover is installed above the support base; the upper and lower ends of the spindle are respectively installed on the support cover and the support base;

[0031] The motor assembly is mounted on a support base and includes a geared motor, motor gears, and spindle gears;

[0032] The motor gear is connected to the geared motor by a key. The motor gear and the spindle gear mesh with each other. The spindle gear is mounted on the outside of the spindle by a cylindrical pin.

[0033] The upper and lower ends of the spindle are respectively mounted on the top and bottom of the support housing via support bearings;

[0034] The screw is mounted on the outside of the spindle via a locking bearing cover, an outer locking bearing, and an inner locking bearing.

[0035] The locking bearing cover is fixedly installed on the top of the support housing. The inner cylindrical surface and lower end face of the outer locking bearing of the locking bearing cover are engaged with the screw, and the outer cylindrical surface and upper end face of the outer ring are engaged with the locking bearing cover. The outer cylindrical surface and upper end face of the inner locking bearing are engaged with the screw, and the inner cylindrical surface and lower end face of the inner ring are engaged with the spindle.

[0036] Furthermore, the first ends of several locking springs are evenly arranged in a circle;

[0037] In the unlocked state, the second end of the locking spring forms an angle of 30° to 60° with the upper surface of the mounting ring. During the locking process, the upper slotted bearing presses down on the locking spring through the upper bearing seat. The mounting ring has a recess of 2° to 10°. When the locking spring is locked, the protrusion of the locking spring moves in the opposite direction beyond the critical surface and is restricted by the concave surface of the mounting ring, thus achieving self-locking. The branches of the locking spring extend horizontally, thereby pressing the steel bar or rope onto the mounting ring, thus locking the flexible arm drive steel bar or rope.

[0038] Furthermore, the recess is frustum-shaped, with the generatrix of the frustum forming an angle of 2° to 10° with the plane of the mounting ring, and the locking spring sinks into the recess after being pressed down.

[0039] Furthermore, the number of turns of the upper or lower rope on the slotted bearing in the locking mechanism of each section of the flexible arm is different. When the upper or lower rope is tensioned, the locking mechanism with more turns exerts a greater force on the locking spring and the locking spring deforms faster, thereby realizing the allocation of the locking sequence of each section of the flexible arm.

[0040] Furthermore, a loop is provided on the outside of the upper or lower rope;

[0041] One end of the sling is fixed to the support housing, and the other end is fixed to the end of a section of the flexible arm connected to the mounting ring.

[0042] The above-mentioned working method of a repeatable locking mechanism based on disc spring unstable switching is characterized by comprising:

[0043] The motor assembly drives the spindle to rotate;

[0044] When the slider moves to the first driving position that engages with the upper screw, the spindle drives the upper screw to rotate through the slider, while the lower screw remains stationary.

[0045] The upper screw drives the upper nut slider to move up and down, thereby locking or unlocking the self-locking mechanism A; the lowest position of the upper nut slider during the up and down movement is recorded as the first position;

[0046] When the self-locking mechanism B needs to work, the upper screw drives the upper nut slider to continue moving downward from the first position, causing the conical coil spring to undergo torsional deformation. The nut slider then pushes the slider downward, causing the slider to move to the second driving position that cooperates with the lower screw. The spindle drives the lower screw to rotate through the slider.

[0047] The upper screw rotates in the opposite direction under the elastic force of the conical coil spring, driving the upper nut slider to move upward to the first position.

[0048] Furthermore, the working method of the above-mentioned repeatable locking mechanism based on disc spring unstable switching includes:

[0049] The motor assembly drives the spindle to rotate;

[0050] When the slider moves to the first driving position that engages with the upper screw, the spindle drives the upper screw to rotate through the slider, while the lower screw remains stationary.

[0051] The upper screw drives the upper nut slider to move up and down. The lowest position of the upper nut slider during the up and down movement is recorded as the first position. The up and down movement of the upper nut slider causes the unlocking drive section or locking drive section of the upper rope to retract.

[0052] When the locking drive section retracts, the upper slotted bearing presses down the second end of the locking spring through the upper bearing seat, causing the first end of the locking spring to slide outward along the radial groove, pressing the steel bar or rope against the upper surface of the mounting ring. The self-locking mechanism A is locked by the friction between the steel bar or rope, the upper surface of the mounting ring, and the locking spring.

[0053] When the unlocking drive section retracts, it pulls the locking spring to reset, thus unlocking the self-locking mechanism A.

[0054] When the self-locking mechanism B needs to work, the upper screw drives the upper nut slider to continue moving downward from the first position. After the conical coil spring undergoes torsional deformation, the nut slider pushes the slider downward, causing the slider to move to the second driving position that cooperates with the lower screw. The spindle drives the lower screw to rotate through the slider, thereby realizing the reversing locking.

[0055] The upper screw rotates in the opposite direction under the elastic force of the conical coil spring, driving the upper nut slider to move upward to the first position.

[0056] Compared with the prior art, the present invention has at least one of the following advantages:

[0057] (1) This invention creatively proposes a repeatable locking mechanism based on disc spring unstable switching. Through the unstable switching of the spring, a motor selectively drives different self-locking mechanisms, which is particularly suitable for selective locking of multi-degree-of-freedom deformation of continuous robots.

[0058] (2) The self-locking mechanism of the present invention adopts non-stable self-locking, which can achieve reliable and stable locking and unlocking by using rope drive. At the same time, it not only ensures the deformation ability of the flexible arm, but also improves the support stiffness of the flexible arm, which will help improve the load-bearing capacity and control accuracy of the flexible arm.

[0059] (3) This invention uses a lasso drive and disc spring clamping support steel bar and other repeatable locking methods to overcome the shortcomings of traditional flexible robots that cannot balance stiffness and deformation. It not only achieves decoupling of multi-segment deformation control of the flexible arm, but also realizes the deformation of the flexible robot to a certain extent. After the deformation is in place, a locking mechanism is used for selective locking, which improves the stiffness of the flexible robot and enhances the load-bearing capacity of the robot. This invention is conducive to realizing the variable stiffness function of flexible robots for space operations such as on-orbit maintenance. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the selective locking drive mechanism for disc spring unstable switching according to the present invention;

[0061] Figure 2 This is a schematic diagram of the disc spring selective switching structure of the repeatable locking mechanism of the present invention.

[0062] Figure 3 This is a schematic diagram of the rope-driven spring-pressed self-locking mechanism in the repeatable locking mechanism of the present invention;

[0063] Figure 4 This is a schematic diagram showing the load balance relationship of the locking bearing on the self-locking spring of the present invention;

[0064] In the diagram, 1-support cover, 2-nut, 3-support bearing cover, 4-support bearing, 5-locking bearing cover, 6-outer locking bearing, 7-nut slider, 8-conical coil spring, 9-screw, 10-slider, 11-inner locking bearing, 12-disc spring, 13-spindle, 14-support seat, 15-spindle gear, 16-cylindrical pin, 17-key, 18-motor gear, 19-gear motor, 20-lower rope, 21-upper rope, 22-lower cable loop B, 23-upper cable loop B, 24-lower cable loop A, 25-upper cable loop A;

[0065] 26-Mounting ring, 27-Steel bar or rope, 28-Locking spring, 29-Bearing housing, 30-Slotted bearing. Detailed Implementation

[0066] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0067] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0068] This invention provides a repeatable locking mechanism based on the unsteady switching of disc springs. Through the unsteady switching and self-locking of the spring, a single motor can selectively lock the multi-degree-of-freedom deformation of mechanisms such as continuous robots. This ensures both the deformability of the flexible arm and improves its support stiffness, which contributes to the load-bearing capacity and control accuracy of the flexible arm. Simultaneously, the lasso structure decouples the deformation control of multiple flexible arm segments, simplifying control complexity. This structure, combined with the flexible arm, can adapt well to different objects and environments, achieving a good balance between the compliance and rigidity of the flexible arm with relatively low weight and power consumption.

[0069] The present invention discloses a repeatable locking mechanism based on disc spring unstable switching, comprising two parts: a selective locking drive mechanism and a rope-driven spring-pressed self-locking mechanism.

[0070] (1) Selective locking drive mechanism

[0071] The selective locking drive mechanism uses a geared motor to drive the nut screw, achieving rope tension and relaxation. Utilizing the instability of the disc spring's axial stiffness, it selectively switches between two axial directions, connecting the screw and drive shaft in different directions to achieve motion output transformation. The motion is then output to the locking mechanism via the rope and lasso, achieving selective locking. This mechanism mainly includes: support cover 1, nut 2, support bearing cover 3, support bearing 4, locking bearing cover 5, outer locking bearing 6, nut slider 7, conical coil spring 8, screw 9, slider 10, inner locking bearing 11, disc spring 12, spindle 13, support seat 14, spindle gear 15, cylindrical pin 16, key 17, motor gear 18, geared motor 19, lower rope 20, upper rope 21, lower lasso sleeve B 22, upper lasso sleeve B 23, lower lasso sleeve A 24, upper lasso sleeve A 25, etc. Figure 1 As shown.

[0072] The support cover 1 and the support seat 14 constitute the support housing as the main support structure. The support cover 1 and the support seat 14 are fixed together by screws and fixed to the workbench. The geared motor 19 is fixed to the support seat 14 by screws, and the motor gear 18 is fixed to the geared motor 19 by key 17. The spindle gear 15 is mounted on the spindle 13 by cylindrical pin 16. The spindle gear 15 and the motor gear 18 transmit the driving torque of the motor to the spindle 13 through tooth surface meshing, causing it to rotate.

[0073] The upper end of the mandrel 13 is fixed to the support cover 1 by a support bearing 4, a support bearing cover 3, and a nut 2. The inner cylindrical surface of the inner ring of the support bearing 4 mates with the mandrel 13, the upper end face of the inner ring of the support bearing 4 contacts the support bearing cover 3, the upper end face of the outer ring of the support bearing 4 does not contact the support bearing cover 3, and the outer cylindrical surface and lower end face of the outer ring of the support bearing 4 mate with the support cover 1. The lower end of the mandrel 13 is fixed to the support seat 14 by another support bearing 4, a mandrel gear 15, and another nut 2. The inner cylindrical surface of the inner ring of the support bearing 4 mates with the mandrel 13, the lower end face of the inner ring of the support bearing 4 contacts the mandrel gear 15, the upper end face of the outer ring of the support bearing 4 does not contact the mandrel gear 15, and the outer cylindrical surface and upper end face of the outer ring of the support bearing 4 mate with the support seat 14. The mandrel 13 is fixed between the support cover 1 and the support seat 14 by the nuts 2 at both ends of the mandrel 13.

[0074] The screw 9 is mounted on the outside of the spindle 13 via the locking bearing cover 5, the outer locking bearing 6, and the inner locking bearing 11. The inner cylindrical surface and lower end face of the outer locking bearing 6 mate with the screw 9, while its outer cylindrical surface and upper end face mate with the locking bearing cover 5. The outer cylindrical surface and upper end face of the inner locking bearing 11 mate with the screw 9, while its inner cylindrical surface and lower end face mate with the spindle 13. The screw 9 and spindle 13 do not contact each other; that is, the rotation of the spindle 13 cannot directly drive the screw 9 to rotate. The upper and lower nut sliders 7 are threaded onto the upper and lower screws 9. The sides of the nut sliders 7 are restricted by the sliding tracks on the inner wall of the support seat 14, allowing them to move vertically only under the drive of the screws 9, thus traction of the rope fixed to the nut sliders 7.

[0075] One end of the conical coil spring 8 is fixed to the nut slider 7, and the other end of the conical coil spring 8 is provided with a pin or boss. The upper end face of the large end of the screw 9 is provided with a groove. When the screw 9 rotates and drives the nut slider 7 to approach the large end of the screw 9, the pin or boss of the conical coil spring 8 will slide into the groove of the large end of the screw 9. As the screw 9 continues to rotate, a certain torque will be applied to the conical coil spring 8, causing it to undergo a certain torsional deformation.

[0076] The inner edge of the disc spring 12 is fixed to the spindle 13, and its outer edge is fixed to the slider 10. The inner wall of the slider 10 is embedded in the concave slide of the spindle 13 by means of an axial boss, and can move up and down in the slide.

[0077] The lower rope 20 and the upper rope 21 are respectively pressed onto the upper and lower nut sliders 7 by screws. The lower rope 20 passes through the lower cable sleeve B 22 and the upper cable sleeve B 23, driving a locking mechanism B. The upper rope 21 passes through the lower cable sleeve A 24 and the upper cable sleeve A 25, driving another locking mechanism A, namely the rope-driven spring-pressed self-locking mechanism.

[0078] One end of the lower cable sleeve B 22, the upper cable sleeve B 23, the lower cable sleeve A 24, and the upper cable sleeve A 25 is fixed in the corresponding holes of the support cover 1 and the support seat 14, and the other end is fixed to the end of a section of the flexible arm connected to the mounting ring 26.

[0079] The geared motor 19 transmits torque to the spindle 13 via the motor gear 18 and the spindle gear 15. This torque then drives the screw 9 at one end via the slider 10, causing the nut slider 7 to move up and down. This changes the tension of the lower rope 20 or the upper rope 21 in a certain direction, thus driving the locking and unlocking of the locking mechanism. Let's assume that in the initial state, the slider 10 is connected to the upper screw, enabling operation of the locking mechanism A:

[0080] 1) When A needs to be locked, the nut slider 7 moves to the lower end of the screw 9, thereby causing the upper rope 21 in the upper cable sleeve A 25 to be tensioned downwards, and causing the upper rope 21 in the lower cable sleeve A 24 to be relaxed (at this time the lower rope 20 has no tension). The upper rope 21 drives the locking mechanism to achieve locking.

[0081] 2) When A needs to be unlocked, the nut slider 7 moves to the upper end of the screw 9, thereby causing the upper rope 21 in the upper cable sleeve A 25 to loosen upward and causing the upper rope 21 in the lower cable sleeve A 24 to contract. After reaching a certain degree, it tightens to unlock the locking mechanism.

[0082] When the nut slider 7 moves downward to a certain extent, it contacts the slider 10, pushing the slider 10 downward. This causes the disc spring 12 supporting the middle slider 10 to deform axially. When the outer edge of the disc spring crosses the inner edge (Note: When the outer edge and inner edge of the disc spring are on the same plane, this disc spring plane is its critical point of motion, which is an unstable equilibrium point, such as...), Figure 2 As shown), the disc spring 12 will spring to the other end, changing direction, thereby driving the slider 10 to switch to the lower end and disengage from the upper screw 9. At this time, the upper conical coil spring 8, in a pre-torsional deformation state, will rotate the screw 9 in the opposite direction and return it to the initial position. Under the axial pressure of the disc spring, during the rotation of the spindle 13, the slider 10 will inevitably be embedded in the drive groove of the lower screw. Thus, the operation of B can be achieved through the slider 10. The operation steps are similar to those of operation A, only in the opposite direction.

[0083] Therefore, the selective locking drive mechanism in this invention uses a geared motor 19 to drive the screw 9 and the nut slider 7 to achieve rope tension and relaxation. This selective mechanism allows for selective and repeatable locking and unlocking in two situations with a single motor drive. Of course, similar structures can achieve selective locking in even more situations. This simplifies the drive system and saves onboard weight, space, and energy resources.

[0084] (2) Rope-driven spring self-locking mechanism

[0085] This invention utilizes the force amplification effect of an inclined locking spring, that is, using a small axial force to generate a large radial force, to achieve clamping and locking between structures. It mainly includes a mounting ring 26, a steel bar or rope 27, a locking spring 28, a bearing seat 29, a slotted bearing 30, etc. Figure 3 As shown.

[0086] Mounting ring 26 is part of the locking structure in the flexible arm. Bolts pass through bearing housing 29 and slotted bearing 30, and are secured with nuts to fix slotted bearing 30 to bearing housing 29. The lower part of bearing housing 29 is fixed to mounting ring 26, while the upper part of bearing housing 29 is fixed to locking spring 28. Locking spring 28 is then mounted to mounting ring 26 with screws, but the lugs of locking spring 28 can slide along the screw holes (i.e., radially). Locking steel bar or rope 27 passes through the holes in both mounting ring 26 and locking spring 28.

[0087] The lower rope 20 or the upper rope 21 is simultaneously wound around the upper and lower sets of slotted bearings 30. When the rope contracts, the locking spring 28 is compressed, its lugs move radially, and press the steel bar or rope 27 against the mounting ring 26. Locking is achieved by the friction between the steel bar or rope 27, the mounting ring 26, and the locking spring 28. Using a steel bar can increase the support stiffness and achieve locking of structures such as flexible arms; using a rope requires it to antagonize other ropes to increase the locking stiffness.

[0088] The rope-driven spring-pressure self-locking mechanism of this invention achieves locking of flexible arms and other structures through the cooperation of a rope and slotted bearings, thereby improving structural rigidity, changing the pressure of the spring on the locking steel bar, and utilizing the friction between them for locking. The specific working process is as follows:

[0089] 1) Wrap one end of the lower rope 20 or the upper rope 21 around the upper and lower slotted bearings 30; in the unlocked state, the second end of the locking spring 28 forms an angle of 30-60° with the upper surface of the mounting ring 26; when the rope is tensioned, the slotted bearing 30 on the locking spring 28 moves towards the fixed slotted bearing 30 at the lower end under tension. The axial displacement of the locking spring 28 will cause radial displacement in each branch. If we assume that in a certain intermediate state, the tension of the rope and the pressure of the locking spring 28 are balanced, then there is a situation where... Figure 4The force balance relationship is shown. It can be seen that during the locking process, the tilt angle gradually decreases, the force amplification effect increases, and a smaller rope tension can generate a larger radial locking force, thus providing a greater radial locking force. When the locking spring 28 is in the plane, the thrust of the left and right springs cancels each other out, achieving self-locking. To ensure stable locking, the mounting ring 26 is designed with a small-angle recess of 2° to 10°. After the locking spring 28 is locked, the convex direction of the locking spring 28 reverses and exceeds the critical surface, and is restricted by the concave surface of the mounting ring 26, thereby achieving a more stable locking through the support of the mounting ring. The branches of the locking spring 28 extend horizontally, thereby pressing the steel bar or rope 27 against the mounting ring 26, thus locking the flexible arm drive steel bar or rope 27.

[0090] 2) By varying the number of turns of the rope around the slotted bearing 30 of the self-locking mechanism used to lock each flexible arm segment, when the upper rope 21 or lower rope 20 is tensioned, the locking mechanism with more turns exerts a greater force on the locking spring 28 through the pulley action of the slotted bearing 30, resulting in faster deformation of the locking spring 28, thus determining the allocation of the locking sequence of different flexible arm segments.

[0091] 3) Fix the other end of rope 20 or 21 to locking spring 28. When this end is tensioned, pull the locking spring 28 from the self-locking state (the locking spring 28 is critically locked and cannot reset itself. After pulling it past the critical point, the locking spring 28 can automatically reset). Under the restoring force of the locking spring 28, it will disengage from the locking steel bar or rope 27, thereby unlocking the installation ring 26 from the steel bar or rope 27.

[0092] 4) The sling uses a universal sleeve with high axial stiffness and low radial stiffness, allowing for omnidirectional bending. Passing the rope through the universal sleeve has minimal, negligible, impact on its axial displacement, while allowing for arbitrary radial bending. Thus, although the drive rope at the front end of the flexible arm (away from the drive mechanism) passes through the rear end (closer to the drive mechanism), the ability to bend radially ensures that the tension of the front drive rope does not affect the rear end. This sling structure decouples the front and rear drive mechanisms.

[0093] Specifically, a selective locking drive mechanism can selectively drive one of two rope-driven spring-pressure self-locking mechanisms. Taking locking mechanism A as an example, the first end of a rope is first fixed to the upper slotted bearing, and then the second end passes around the upper and lower slotted bearings and is inserted into a cable loop. After exiting the cable loop, it enters the support cover or support seat, passes through the upper nut slider, and is then fixed to the upper slotted bearing. Finally, the part of the rope that passes through the upper nut slider is pressed against the upper nut slider to achieve a fixed connection between the two. Similarly, taking locking mechanism B as an example, the first end of a rope is first fixed to the lower slotted bearing, and then the second end passes around the lower and upper slotted bearings and is inserted into a cable loop. After exiting the cable loop, it enters the support cover or support seat, passes through the lower nut slider, and is then fixed to the lower slotted bearing. Finally, the part of the rope that passes through the upper nut slider is pressed against the lower nut slider to achieve a fixed connection between the two.

[0094] When it is necessary to lock the locking mechanism A, the upper nut slider moves downward, causing the upper rope in the upper cable sleeve A 25 to move downward, ensuring that the upper nut slider does not contact the slider 10 when the locking mechanism A is locked, and the conical coil spring is not compressed at this time.

[0095] When it is necessary to switch to locking mechanism B, the upper nut slider continues to move downward, compressing the conical coil spring until it pushes slider 10 to change direction.

[0096] As can be seen, this structure enables the large displacement of the rope to generate a large locking force for the locking mechanism. When locking is required, the steel bar or rope 27 in an antagonistic state can be firmly pressed onto the mounting ring 26, greatly improving the stiffness of the flexible arm. Furthermore, it enables independent control and independent deformation of each section of the flexible arm at the front and rear ends, simplifying the deformation control of the flexible arm.

[0097] This invention utilizes a disc spring-based unstable switching locking mechanism. Through the unstable switching and self-locking of the spring, a single motor selectively locks the multi-degree-of-freedom deformation of a continuous robot. This ensures both the deformability of the flexible arm and improves its support stiffness, which contributes to enhancing the load-bearing capacity and control precision of the flexible arm. Simultaneously, a lasso structure decouples the deformation control of multiple flexible arm segments, simplifying control complexity. This structure, combined with the flexible arm, can adapt well to different objects and environments, effectively balancing the flexibility and rigidity of the flexible arm.

[0098] Traditional flexible arm control methods use one motor to control one degree of freedom. This invention, however, utilizes a designed disc spring unstable switching mechanism to achieve selective locking control of two states or two degrees of freedom driven by a single motor. This enables repeatable locking of continuous robots and selective locking of the flexible arm, thereby achieving variable stiffness in the robot and balancing the compliance and rigidity of the flexible arm. Compared to traditional locking mechanisms, this invention offers better selectivity, a better balance of rigidity and flexibility, and easier control. It also boasts better adaptability, flexibility, compliance, and rigidity, with the potential for higher load-bearing capacity and control precision, while significantly saving onboard weight, space, and energy.

[0099] Traditional flexible arms have relatively low locking force and a single locking mode, some even lacking locking altogether. This results in low stiffness and consequently, low load-bearing capacity, making precise control of the flexible body difficult. Much flexible arm research focuses on altering the closed-loop stiffness of the structure and control system by changing the motor's driving force. Therefore, their load-bearing capacity depends entirely on the motor's output torque and the transmission structure; control accuracy is limited by the motor's servo control precision. This invention, however, utilizes the force amplification effect of a small-angle spring to press the antagonistic support steel bar or rope onto the mounting ring, achieving a stable lock on the flexible arm and other structures, thus improving the support stiffness of the flexible arm structure. Selective locking of the locking mechanism ensures different stiffness selection under various application conditions, balancing the robot's flexibility and variable stiffness, as well as the flexible arm's deformation and load-bearing capacity. Segmented, gradual stiffness adjustment reduces control difficulty and improves control accuracy. Furthermore, the motor does not need to be powered after locking, saving energy.

[0100] In traditional flexible arms, the ropes pass directly through each segment. Under complex deformation conditions, the radial component of the tension and friction of the driving rope at the front end directly affect the rear end. This non-ideal interference not only affects the complexity of the control algorithm at the rear end but also weakens the deformation capability of the flexible arm at the rear end. This invention, however, employs a lasso structure, whose radially arbitrary bending capability decouples the deformation control of each segment of the flexible arm, simplifying the control complexity.

[0101] As space debris increases, so does the threat it poses to satellites. The benefits of clearing space debris to protect high-value satellites are growing. This invention's robot can perform operations such as space debris clearing around celestial bodies and on-orbit maintenance. With the increasing demand for automation in various fields, this invention can also enable automated refueling and charging in automobiles and automated industrial painting. In conclusion, this mechanism, combined with a flexible arm, has broad application prospects.

[0102] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0103] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A repeatable locking mechanism based on disc spring unstable switching, characterized in that, It includes a support housing, a spindle (13), a motor assembly, a screw (9), a slider (10), a nut slider (7), a conical coil spring (8), a disc spring (12), and a self-locking mechanism; The spindle (13) is located inside the support housing, and the upper and lower ends of the spindle (13) are respectively installed on the top and bottom of the support housing; the motor assembly is used to drive the spindle (13) to rotate; The mandrel (13) is divided into an upper section, a middle section and a lower section. Two screws (9) are respectively located on the outer side of the upper section and the lower section of the mandrel (13). The two screws (9) are respectively referred to as the upper screw and the lower screw. The middle section of the mandrel (13) is provided with a first slide rail in the vertical direction. The first protrusion provided on the inner side of the slider (10) is embedded in the first slide rail. When the slider (10) moves along the mandrel (13) to the first driving position that cooperates with the upper screw, the mandrel (13) drives the upper screw to rotate through the slider (10). When the slider (10) moves along the mandrel (13) to the second driving position that cooperates with the lower screw, the mandrel (13) drives the lower screw to rotate through the slider (10). The two nut sliders (7) are referred to as the upper nut slider and the lower nut slider, respectively. The upper nut slider and the lower nut slider are installed on the outside of the upper screw and the lower screw, respectively. The rotation of the screw (9) drives the nut sliders (7) to move up and down along the screw (9). The up and down movement of the upper nut slider and the lower nut slider is used to realize the locking or unlocking of two different self-locking mechanisms. The screw (9) has a first boss at its end. A conical coil spring (8) is sleeved on the outside of the screw (9) and located between the first boss and the nut slider (7). The conical coil spring (8) is used to generate torsional deformation under the action of the nut slider (7) and to realize the reset of the nut slider (7) after the nut slider (7) stops moving. The slider (10) moves along the spindle (13) under the push of the nut slider (7). The inner edge of the disc spring (12) is connected to the outer side of the middle section of the spindle (13), and the outer edge of the disc spring (12) is connected to the inner side of the slider (10). The up and down movement of the slider (10) drives the outer edge of the disc spring (12) to move relative to the inner edge of the disc spring (12), thereby realizing the switching of the first steady state and the second steady state of the disc spring (12). The disc spring (12) in the first steady state and the second steady state are respectively used to realize the positioning of the slider (10) in the first driving position and the second driving position.

2. The repeatable locking mechanism based on disc spring unstable switching of claim 1, wherein, The self-locking mechanism includes a mounting ring (26), a bearing housing (29), and a slotted bearing (30); There are two bearing housings (29), which are referred to as the upper bearing housing and the lower bearing housing respectively; there are two slotted bearings (30), which are referred to as the upper slotted bearing and the lower slotted bearing respectively; The first ends of several locking springs (28) are respectively installed in several radial grooves opened on the upper surface of the mounting ring (26), and the second ends are fixedly connected to the upper bearing seat. The upper slotted bearing is installed on the upper bearing seat; the lower bearing seat is installed on the lower surface of the mounting ring (26), and the lower slotted bearing is installed on the lower bearing seat. The first end of the upper rope (21) or the lower rope (20) is simultaneously wound around the upper slotted bearing and the lower slotted bearing, and the second end is fixedly connected to the locking spring (28). The upper rope (21) or the lower rope (20) passes through the upper nut slider or the lower nut slider respectively and is fixedly connected to the upper nut slider or the lower nut slider at that point. The part between the first end of the upper rope (21) or the lower rope (20) and the fixed connection point is called the locking drive section, and the part between the second end of the upper rope (21) or the lower rope (20) and the fixed connection point is called the unlocking drive section. The mounting ring (26) has a first through hole, and the first end of the locking spring (28) has a second through hole. One end of the steel bar or rope is connected to the flexible arm drive motor, and the other end passes through the first through hole and the second through hole in sequence to connect to the end of the flexible arm. When the locking drive section retracts, the upper slotted bearing presses down the second end of the locking spring (28) through the upper bearing seat, causing the first end of the locking spring (28) to slide outward along the radial groove, pressing the steel bar or rope against the upper surface of the mounting ring (26), and locking is achieved through the friction between the steel bar or rope, the upper surface of the mounting ring (26) and the locking spring (28); When the unlocking drive section retracts, it pulls the locking spring (28) to reset, and the first through hole, the second through hole, and the steel bar or rope are coaxial, thus unlocking.

3. The repeatable locking mechanism based on disc spring unstable switching of claim 1, wherein, The inner wall of the support housing is provided with a second slide rail in the vertical direction; The inner side of the nut slider (7) is threadedly connected to the outer side of the screw (9). The outer side of the nut slider (7) is engaged with the second slide rail provided on the inner wall of the support housing. When the screw (9) rotates, the movement of the nut slider (7) is limited by the second slide rail.

4. The repeatable locking mechanism based on disc spring unstable switching according to claim 1, characterized in that, The screw (9) has a first groove on its first protrusion. One end of the conical coil spring (8) is fixedly connected to the nut slider (7). The other end of the conical coil spring (8) is provided with a pin. The movement of the nut slider (7) drives the other end of the conical coil spring (8) to cooperate with the first groove through the pin. The continued movement of the nut slider (7) causes the conical coil spring (8) to undergo torsional deformation. A second groove matching the slider (10) is formed on the first boss of the screw (9); When the slider (10) moves to the first driving position or the second driving position, the slider (10) is embedded in the second groove to achieve cooperation with the screw (9); When the disc spring (12) is in the first steady state, the outer edge of the disc spring (12) is above the inner edge. When the disc spring (12) is in the second steady state, the outer edge of the disc spring (12) is below the inner edge.

5. The repeatable locking mechanism based on disc spring unstable switching according to claim 1, characterized in that, The support housing includes a support cover (1) and a support base (14); The support cover (1) is installed above the support base (14); the upper and lower ends of the spindle (13) are respectively installed on the support cover (1) and the support base (14); The motor assembly is mounted on the support (14) and includes a geared motor (19), a motor gear (18) and a spindle gear (15). The motor gear (18) is connected to the geared motor (19) via a key (17). The motor gear (18) and the spindle gear (15) mesh with each other. The spindle gear (15) is mounted on the outside of the spindle (13) via a cylindrical pin. The upper and lower ends of the mandrel (13) are respectively mounted on the top and bottom of the support housing via support bearings; The screw (9) is mounted on the outside of the spindle (13) via the locking bearing cover (5), the outer locking bearing (6) and the inner locking bearing (11); The locking bearing cover (5) is fixedly installed on the top of the support housing. The inner cylindrical surface and the lower end face of the outer locking bearing (6) of the locking bearing cover (5) are engaged with the screw (9), and the outer cylindrical surface and the upper end face of the outer ring are engaged with the locking bearing cover (5). The outer cylindrical surface and the upper end face of the inner locking bearing (11) are engaged with the screw (9), and the inner cylindrical surface and the lower end face of the inner ring are engaged with the spindle (13).

6. A repeatable locking mechanism based on disc spring unstable switching according to claim 2, characterized in that, The first ends of several locking springs (28) are evenly arranged in a circle; In the unlocked state, the second end of the locking spring (28) is inclined at an angle of 30 to 60 degrees to the upper surface of the mounting ring (26); during the locking process, the upper slotted bearing presses down the locking spring (28) through the upper bearing seat; the mounting ring (26) has a recess of 2 to 10 degrees. When the locking spring (28) is locked, the protrusion of the locking spring (28) is reversed and exceeds the critical surface, and is restricted by the concave surface of the mounting ring (26), thereby achieving self-locking; each branch of the locking spring (28) extends in the horizontal direction, thereby pressing the steel bar or rope (27) onto the mounting ring (26), thereby achieving the locking of the flexible arm drive steel bar or rope (27).

7. A repeatable locking mechanism based on disc spring unstable switching according to claim 2, characterized in that, The number of turns of the upper rope (21) or lower rope (20) on the slotted bearing (30) in the locking mechanism of each section of the flexible arm is different. When the upper rope (21) or lower rope (20) is tensioned, the locking mechanism with more turns exerts a greater force on the locking spring (28), and the locking spring (28) deforms faster, thereby realizing the allocation of the locking sequence of each section of the flexible arm.

8. A repeatable locking mechanism based on disc spring unstable switching according to claim 2, characterized in that, A loop is provided on the outside of the upper rope (21) or the lower rope (20); One end of the cable is fixed to the support housing, and the other end is fixed to the end of a section of the flexible arm connected to the mounting ring (26).

9. The working method of a repeatable locking mechanism based on disc spring unstable switching according to any one of claims 1-8, characterized in that, include: The motor assembly drives the spindle (13) to rotate; When the slider (10) moves to the first driving position that engages with the upper screw, the spindle (13) drives the upper screw to rotate through the slider (10), while the lower screw remains stationary; The upper screw drives the upper nut slider to move up and down, thereby locking or unlocking the self-locking mechanism A; the lowest position of the upper nut slider during the up and down movement is recorded as the first position; When the self-locking mechanism B needs to work, the upper screw drives the upper nut slider to continue moving downward from the first position, causing the conical coil spring (8) to undergo torsional deformation. Then, the nut slider pushes the slider (10) downward, causing the slider (10) to move to the second driving position that cooperates with the lower screw. The spindle (13) drives the lower screw to rotate through the slider (10). The upper screw rotates in the opposite direction under the elastic force of the conical coil spring (8), driving the upper nut slider to move upward to the first position.

10. The working method of a repeatable locking mechanism based on disc spring unstable switching according to any one of claims 2-8, characterized in that, include: The motor assembly drives the spindle (13) to rotate; When the slider (10) moves to the first driving position that engages with the upper screw, the spindle (13) drives the upper screw to rotate through the slider (10), while the lower screw remains stationary; The upper screw drives the upper nut slider to move up and down. The lowest position of the upper nut slider during the up and down movement is recorded as the first position. The up and down movement of the upper nut slider causes the unlocking drive section or locking drive section of the upper rope (21) to contract. When the locking drive section retracts, the upper slotted bearing presses down the second end of the locking spring (28) through the upper bearing seat, causing the first end of the locking spring (28) to slide outward along the radial groove, pressing the steel bar or rope against the upper surface of the mounting ring (26). The self-locking mechanism A is locked by the friction between the steel bar or rope, the upper surface of the mounting ring (26) and the locking spring (28). When the unlocking drive section retracts, the unlocking drive section pulls the locking spring (28) to reset, thereby unlocking the self-locking mechanism A; When the self-locking mechanism B needs to work, the upper screw drives the upper nut slider to continue moving downward from the first position, causing the conical coil spring (8) to undergo torsional deformation. The nut slider then pushes the slider (10) downward, causing the slider (10) to move to the second driving position that cooperates with the lower screw. The spindle (13) drives the lower screw to rotate through the slider (10), thereby achieving reversing locking. The upper screw rotates in the opposite direction under the elastic force of the conical coil spring (8), driving the upper nut slider to move upward to the first position.

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