Compliant robot based on changing the force of circular spring

Abstract

The invention belongs to the field of robots, and discloses a compliant robot based on changing the force of a circumferential spring sheet, comprising an upper platform, a first variable stiffness module, a variable stiffness joint, a second variable stiffness module and a lower platform; the circumferential spring sheet in the second variable stiffness module is fixed by a support column, which is equivalent to a free cantilever beam, and the change in the position of the second sliding component on the circumferential spring sheet will cause the circumferential spring sheet to be deformed by force, thereby realizing variable stiffness and having a larger output torque; the Archimedean spiral plate rotates to make the first connecting rod move linearly, thereby realizing variable stiffness; the invention adopts a stepping motor, a first synchronous pulley, a second synchronous pulley, and a bevel gear set to realize the rapid displacement of the second sliding component, and realizes the rapid displacement of the first sliding component through the Archimedean spiral plate, and the response is rapid; by adopting circumferential spring sheets with different elasticity or bevel gear sets with different moduli, different stiffness characteristics and output torques can be obtained to meet different stiffness characteristic requirements; and the invention is used to realize the flexible drive of the robot.

Description

Technical Field

[0001] The invention relates to a compliant robot, in particular to a compliant robot based on changing the force of a circumferential spring sheet. Background Art

[0002] Traditional robots are driven by high-rigidity drivers, which enable the actuators to achieve precise positioning and trajectory tracking. However, since the working space and working mode of high-rigidity drivers are fixed, robots may collide with humans in life and work, which in turn reduces the safety of robot-human contact and interaction and the robot's adaptability to unknown and complex environments. Therefore, traditional robots with high-strength drivers do not have a high level of environmental adaptability, human-machine interaction safety, and the ability to respond to external events in a timely manner.

[0003] At present, there is also a compliant robot that is driven by a variable stiffness joint. When a collision occurs, the compliant element can bend or stretch, which can buffer and store energy. The robot with a compliant drive has high bionic characteristics and plays an important role in ensuring the safety of human-machine interaction and improving the robot's ability to adapt to complex environments.

[0004] However, the existing compliant robots have a complex structure and require more drivers, resulting in slow response. In addition, the existing compliant robots have large deformation but small output torque and cannot meet different stiffness characteristic requirements. Summary of the invention

[0005] The present invention aims to provide a compliant robot based on changing the force of a circumferential spring sheet, so as to solve the problems of the existing compliant robots, such as slow response, large deformation but small output torque, and inability to meet the requirements of different stiffness characteristics.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A compliant robot based on changing the force of a circumferential spring sheet comprises an upper platform, a first variable stiffness module, a variable stiffness joint, a second variable stiffness module and a lower platform;

[0008] The first variable stiffness module includes a first rotation drive element, an Archimedean spiral plate, a plurality of first connecting rods, a plurality of first sliding assemblies, and a plurality of first sliding rails;

[0009] The first rotating driving element is fixed on the upper platform, the Archimedean spiral plate is connected to the output end of the first rotating driving element, a plurality of spiral grooves are provided on the Archimedean spiral plate, the number of the spiral grooves is equal to the number of the first connecting rods, a first connecting rod is slidably clamped in each spiral groove, the Archimedean spiral plate rotates to drive the first connecting rod to perform linear motion along the radial direction of the Archimedean spiral plate; the number of the first slide rails and the number of the first sliding assemblies are equal to the number of the first connecting rods, a first sliding assembly is fixed on each first connecting rod, and a first sliding assembly is slidably arranged on each first slide rail;

[0010] The second variable stiffness module includes a driving mechanism, a circumferential spring sheet, a plurality of second sliding components and a plurality of second sliding rails arranged on the circumferential spring sheet;

[0011] A support column is arranged between the circumferential spring sheet and the lower platform, a plurality of second slide rails are arranged on the circumferential spring sheet at intervals along the circumference thereof, the length direction of the second slide rails is arranged along the radial direction of the circumferential spring sheet, and a second slide assembly is slidably arranged on each second slide rail; the driving mechanism drives the second slide assembly to perform linear motion in a direction close to or away from the center of the circumferential spring sheet;

[0012] There are multiple variable stiffness joints, and their number is equal to the number of first connecting rods. Each variable stiffness joint includes a ball joint, a telescopic rod, a sleeve, a second connecting rod and a Hook's joint connected in sequence. The ball joint support is fixedly connected to the first connecting rod, the ball joint ball is fixedly connected to the telescopic rod, the telescopic rod is movably arranged in the sleeve, and the second connecting rod and the telescopic rod, as well as the second connecting rod and the first connecting rod are all hinged; the Hook's joint is fixedly arranged at the bottom of the sleeve, and the Hook's joint is fixedly connected to the second sliding assembly.

[0013] As a limitation of the present invention: the first variable stiffness module also includes a transmission mechanism, which is located between the upper platform and the Archimedean spiral plate; the transmission mechanism includes an active disc and a passive disc; the active disc is fixedly connected to the output end of the first rotating drive element, a spring guide support column is fixedly provided at the center of the passive disc, and the spring guide support column is movably connected to the active disc; the Archimedean spiral plate is detachably sleeved on the output shaft of the passive disc;

[0014] A plurality of cylinders are fixed at the bottom end of the active disc; a plurality of groups of driven components are arranged on the passive disc, and the plurality of groups of driven components are arranged at intervals along the circumference of the passive disc, and the driven components include two constraint plates fixed in parallel on the passive disc, a triangular plate is slidably arranged between the two constraint plates, the cylinder extends into a groove surrounded by the triangular plate and the two constraint plates, the hypotenuse of the triangular plate is arranged close to the cylinder, a guide column is arranged on the spring guide support column facing the triangular plate, the triangular plate is slidably arranged on the guide column, a spring is sleeved on the guide column, one end of the spring is fixedly connected to the triangular plate, and the other end is fixedly connected to the spring guide support column; the number of cylinders is equal to the number of driven components.

[0015] As a further limitation of the present invention: the transmission mechanism also includes a forward ratchet and a reverse ratchet arranged between the active disc and the passive disc, the forward ratchet is arranged close to the active disc, and the forward ratchet and the reverse ratchet are both fixedly connected to the upper platform; there are four groups of driven assemblies, and the triangular plates in two adjacent groups of driven assemblies are provided with a first pawl meshing with the forward ratchet, and the hypotenuses of the triangular plates in the two groups of driven assemblies are both against the cylinder; in addition, the triangular plates in the two adjacent groups of driven assemblies are provided with a second pawl meshing with the reverse ratchet;

[0016] The first ratchet is used to limit the passive disc to rotate counterclockwise, and the second ratchet is used to limit the passive disc to rotate clockwise.

[0017] As a further limitation of the present invention, the number of the first connecting rods is six, the Archimedean spiral plate comprises an upper plate and a lower plate which are arranged at intervals, the upper plate is provided with four spiral grooves, the lower plate is provided with two spiral grooves, the positions on the lower plate corresponding to the spiral grooves of the upper plate are provided with a hollow structure, the six first connecting rods are respectively slidably clamped in a spiral groove, and the Archimedean spiral plate rotates to drive the first connecting rods to perform linear motion along the radial direction of the Archimedean spiral plate;

[0018] A transmission shaft is fixedly arranged at the bottom of the passive disc, and the transmission shaft is the output shaft of the passive disc. The Archimedean spiral plate is sleeved on the transmission shaft. A first connecting block is fixedly arranged on the upper plate, and the first connecting block is detachably connected to the transmission shaft through a fastener. A second connecting block is fixedly arranged on the lower plate, and the second connecting block is also detachably connected to the transmission shaft through a fastener.

[0019] As another limitation of the present invention, the second sliding assembly includes a screw rotatably arranged on the circumferential spring sheet and a screw seat threadedly sleeved on the screw, the screw seat is axially arranged along the radial direction of the circumferential spring sheet, and the screw seat is slidably clamped on the second slide rail;

[0020] The driving mechanism is fixed on the lower platform, and the driving mechanism includes a second rotating driving element and a transmission assembly. The input end of the transmission assembly is connected to the output end of the second rotating driving element, and the output end of the transmission assembly is connected to the screw. The second rotating driving element drives the screw to rotate through the transmission assembly so that the screw seat performs a linear motion along the radial direction of the circumferential spring sheet.

[0021] As a further limitation of the present invention: the second rotating driving element is a stepping motor, and the transmission assembly includes a first synchronous pulley, multiple second synchronous pulleys, a synchronous belt, multiple stepped shafts and multiple bevel gear groups; the number of second synchronous pulleys, the number of stepped shafts, the number of bevel gear groups and the number of second slide rails are equal, the first synchronous pulley is fixed on the output shaft of the stepping motor, the first synchronous pulley and the second synchronous pulley are driven by a synchronous belt, the stepped shaft is fixed on the second synchronous pulley, the rotation axes of the first synchronous pulley and the second synchronous pulley are parallel to the axial direction of the stepped shaft, the input end of the bevel gear group is connected to the stepped shaft, and the output end of the bevel gear group is connected to the lead screw.

[0022] As another limitation of the present invention: an unfolding mechanism is provided on the second sliding assembly, the unfolding mechanism includes two hinges, each hinge includes a plurality of connecting rods, the connecting rods include a first straight rod and a second straight rod that are fixedly connected, the angle formed by the first straight rod and the second straight rod is an obtuse angle, and the plurality of connecting rods are hingedly connected end to end to form a ring structure; the two hinges are cross-arranged up and down, the overlapping positions of the two hinges are hingedly connected, and the two hinges are hingedly connected to the second sliding assembly at positions corresponding to the second sliding assembly.

[0023] As a further limitation of the present invention: the circumferential spring piece is made of 45# steel plate.

[0024] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0025] The present invention comprises an upper platform, a first variable stiffness module, a variable stiffness joint, a second variable stiffness module and a lower platform; the circumferential spring sheet in the second variable stiffness module is fixed by a support column, which is equivalent to a free cantilever beam. When the lead screw rotates, the second sliding component approaches or moves away from the center of the circumferential spring sheet. At this time, the position of the second sliding component on the circumferential spring sheet will change, and the circumferential spring sheet will be deformed by force to achieve variable stiffness; and because the circumferential spring sheet is made of 45# steel, it has the characteristic of generating a large elastic force under a small deformation. The use of the circumferential spring sheet enables the present invention to have a large output torque;

[0026] In the first variable stiffness module, the active disc is driven to rotate by the first rotating driving element, and the active disc drives the passive disc to rotate, thereby rotating the Archimedean spiral plate, so that the first connecting rod moves linearly along the radial direction of the Archimedean spiral plate, thereby realizing the variable stiffness characteristic;

[0027] When the cylinder on the active disc contacts the triangular plate, the triangular plate will move straight toward the center of the passive disc, thereby compressing the spring and achieving variable stiffness characteristics;

[0028] The present invention adopts a stepping motor, a first synchronous pulley, a second synchronous pulley, a synchronous belt, a bevel gear set and other structures to realize the rapid displacement of the second sliding component, and the Archimedean spiral plate can realize the rapid displacement of the first sliding component, which has the characteristics of rapid response, reduces the number of drivers used, and has a simple structure;

[0029] The present invention can obtain different stiffness characteristics and different output torques by adopting circumferential spring pieces with different elasticity or selecting bevel gear sets with different modules, thereby meeting different stiffness characteristic requirements.

[0030] In summary, the present invention can not only achieve variable stiffness, but also has the characteristics of fast response, small deformation, large output torque, and can meet the requirements of different stiffness characteristics; the present invention is suitable for the robotics industry and is used to achieve flexible driving of robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0033] Figure 2 It is a structural schematic diagram of a first variable stiffness module in an embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the structure of the upper plate, the lower plate, the first connecting rod and the sliding rod in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the upper plate, the lower plate, and the first connecting block in an embodiment of the present invention;

[0036] Figure 5 This is a schematic structural diagram of the lower plate, the second connecting block, and the transmission shaft in an embodiment of the present invention;

[0037] Figure 6 An exploded view of an Archimedean spiral plate in an embodiment of the present invention;

[0038] Figure 7 It is a schematic diagram of the structure of the forward ratchet, the reverse ratchet, and the passive disc in the embodiment of the present invention;

[0039] Figure 8 It is a schematic diagram of the structure of a cylinder and a triangular plate in an embodiment of the present invention;

[0040] Fig. 9 It is a schematic diagram of the structure of the active disc and the cylinder in the embodiment of the present invention;

[0041] Fig.10 It is a schematic diagram of the structure of the active disc and the passive disc in the embodiment of the present invention;

[0042] Fig.11 Schematic diagram of the structure of a variable stiffness joint in an embodiment of the present invention;

[0043] Fig.12 is a schematic structural diagram of a second variable stiffness module in an embodiment of the present invention;

[0044] Fig.13 It is a schematic structural diagram of a circumferential spring piece, a support column, and a lower platform in an embodiment of the present invention;

[0045] Fig.14 Schematic diagram of the structure of the unfolding mechanism in the embodiment of the present invention.

[0046] In the figure: 1-upper platform, 2-lower platform;

[0047] 3-first variable stiffness module, 301-first rotating drive element, 302-coupling, 303-Archimedes spiral plate, 3031-upper plate, 3032-lower plate, 3033-spiral groove, 3034-first connecting block, 3035-second connecting block, 304-first connecting rod, 305-sliding block, 306-first sliding rail, 307-active disc, 308-passive disc, 309-cylinder, 310-spring guide support column, 311-screw, 312-nut, 313 - annular groove, 314 - first driven assembly, 315 - second driven assembly, 316 - third driven assembly, 317 - fourth driven assembly, 318 - restraining plate, 319 - triangular plate, 320 - groove, 321 - pad, 322 - guide column, 323 - spring, 324 - forward ratchet, 325 - reverse ratchet, 326 - ratchet sleeve, 327 - fixed rod, 328 - first ratchet, 329 - second ratchet, 330 - transmission shaft, 331 - sliding rod, 332 - fixed block;

[0048] 4-variable stiffness joint, 41-ball joint, 42-telescopic rod, 43-sleeve, 44-second connecting rod, 45-Hooke's hinge;

[0049] 5-second variable stiffness module, 501-circumferential spring sheet, 502-second slide rail, 503-support column, 504-screw, 505-screw seat, 506-second rotation drive element, 507-first synchronous pulley, 508-second synchronous pulley, 509-synchronous belt, 510-step shaft, 511-bevel gear set, 512-unfolding mechanism, 513-hinge, 514-connecting rod, 5141-first straight rod, 5142-second straight rod, 5143-suspender rotating pair. DETAILED DESCRIPTION

[0050] It should be understood that the compliant robot based on changing the force of the circumferential spring sheet described here is a preferred embodiment, which is only used to illustrate and explain the present invention and does not constitute a limitation of the present invention.

[0051] like Figure 1 to Figure 14 As shown, this embodiment includes an upper platform 1, a first variable stiffness module 3, a variable stiffness joint 4, a second variable stiffness module 5 and a lower platform 2. The first variable stiffness module 3 realizes variable stiffness by controlling the movement of the first sliding component, and the second variable stiffness module 5 realizes variable stiffness by controlling the movement of the second sliding component to change the force of the circumferential spring piece 501; the second rotating drive element 506, the first synchronous pulley 507, the second synchronous pulley 508, the synchronous belt 509, the bevel gear set 511 and other structures can realize the rapid displacement of the second sliding component, and the Archimedean spiral plate 303 can realize the rapid displacement of the first sliding component, which has the characteristic of rapid response; the circumferential spring piece 501 has the characteristic of being able to generate a large elastic force under a small deformation, so that the present invention has a large output torque.

[0052] 1. The first variable stiffness module 3;

[0053] like Figure 2 As shown, the first variable stiffness module 3 includes a first rotation drive element 301, a transmission mechanism, an Archimedean spiral plate 303, a plurality of first connecting rods 304, a plurality of first sliding assemblies, and a plurality of first sliding rails 306;

[0054] The first rotation driving element 301 is fixed on the upper platform 1, and the Archimedean spiral plate 303 is connected to the output end of the first rotation driving element 301. In this embodiment, the first rotation driving element 301 adopts an existing stepping motor, and of course, any other existing structure can be selected as long as it can provide a rotation driving force. The transmission mechanism is located between the upper platform 1 and the Archimedean spiral plate 303, such as Figure 2 As shown, a coupling 302 is provided at the output end of the first rotation driving element 301, the transmission mechanism is connected to the coupling 302, and the Archimedean screw plate 303 is connected to the transmission mechanism.

[0055] The transmission mechanism includes an active disc 307 and a passive disc 308. The active disc 307 is fixedly connected to the output end of the first rotating drive element 301, that is, Figure 2 As shown, the driving disc 307 is fixedly connected to the coupling 302. Fig. 9 As shown, a plurality of cylinders 309 extending toward the passive disk 308 are fixedly disposed at the bottom end of the active disk 307. Figure 7 , 8As shown, a spring guide support column 310 is fixed at the center of the passive disc 308, and the spring guide support column 310 is movably connected to the active disc 307; the movably connected method here is: Fig.10 As shown, a screw rod 311 is fixed on the spring guide support column 310, a nut 312 is sleeved on the screw rod 311, an annular groove 313 and a through hole are provided on the active disc 307 at the position corresponding to the screw rod 311, the inner diameter of the through hole is slightly larger than the diameter of the screw rod 311 but smaller than the diameter of the nut 312, the inner diameter of the annular groove 313 is larger than the diameter of the nut 312, the screw rod 311 passes through the through hole and extends into the annular groove 313, the nut 312 is located in the annular groove 313, thereby achieving a snap connection, and the nut 312 and the screw rod 311 are not tightened, the top of the spring guide support column 310 does not abut the active disc 307, so that the active disc 307 and the passive disc 308 can rotate relative to each other. Of course, the spring guide support column 310 and the active disc 307 can also be connected in any structure in the prior art, such as realizing a movable connection through a bearing.

[0056] When the active disc 307 rotates, the passive disc 308 rotates. The specific structure is as follows: the passive disc 308 is provided with multiple groups of driven components, such as Figure 7 As shown, in this embodiment, the number of driven assemblies is set to four groups, and the four groups of driven assemblies are arranged at intervals along the circumference of the passive disc 308, and the interval between two adjacent driven assemblies is 90 degrees. The four groups of driven assemblies include a first driven assembly 314, a second driven assembly 315, a third driven assembly 316, and a fourth driven assembly 317. Each group of driven assemblies includes two constraint plates 318 fixedly arranged in parallel on the passive disc 308, and a triangular plate 319 is slidably arranged between the two constraint plates 318, as shown in FIG. Figure 7 , 8 As shown, the cylinder 309 extends into the groove 320 formed by the triangular plate 319 and the two restraining plates 318. In this embodiment, a pad 321 is fixed on the bottom surface of the triangular plate 319. The triangular plate 319, the pad 321 and the two restraining plates 318 form the groove 320. The hypotenuse of the triangular plate 319 is arranged close to the cylinder 309, and as shown in FIG. Figure 7 As shown, the triangular plate 319 in the first driven assembly 314 and the triangular plate 319 in the third driven assembly 316 are symmetrical about the spring guide support column 310 , and the triangular plate 319 in the second driven assembly 315 and the triangular plate 319 in the fourth driven assembly 317 are symmetrical about the spring guide support column 310 .

[0057] like Figure 7As shown, a guide post 322 is provided on the spring guide support post 310 toward the triangular plate 319, a sliding hole is provided on the triangular plate 319, and the guide post 322 extends into the sliding hole so that the triangular plate 319 is slidably provided on the guide post 322. A spring 323 is sleeved on the guide post 322, one end of the spring 323 is fixedly connected to the triangular plate 319, and the other end is fixedly connected to the spring guide support post 310.

[0058] like Figure 7 , 8 As shown, the number of cylinders 309 is equal to the number of driven components. In order to clearly see the positional relationship between the cylinder 309 and the triangular plate 319, Figure 8 The middle cylinder 309 is shown separately. In fact, the cylinder 309 is fixed to the bottom of the active disk 307. Fig. 9 . The working principle is: when the active disc 307 rotates counterclockwise with the first rotating drive element 301, the cylinder 309 in the first driven component 314 is against the triangular plate 319, and the cylinder 309 applies a force to the triangular plate 319, which can be decomposed into a force along the radial direction of the passive disc 308 and a force perpendicular to the radial direction of the passive disc 308. The force along the radial direction of the passive disc 308 causes the triangular plate 319 in the first driven component 314 to perform a linear motion along the radial direction of the passive disc 308, the spring 323 is compressed, and the overall stiffness changes; the force perpendicular to the radial direction of the passive disc 308 causes the first driven component 314 to rotate counterclockwise. The movement principle of the second driven component 315 is the same as that of the first driven component 314, and will not be repeated. This part causes the passive disc 308 to rotate counterclockwise. However, it should be noted that when the active disc 307 rotates counterclockwise, the cylinder 309 in the third driven component 316 does not exert force on the triangular plate 319, and the cylinder 309 in the fourth driven component 317 does not exert force on the triangular plate 319. Similarly, when the active disc 307 rotates clockwise, the third driven component 316 and the fourth driven component 317 make linear motion along the radial direction of the passive disc 308, and the spring 323 corresponding to the third driven component 316 and the fourth driven component 317 is compressed. At the same time, the third driven component 316 and the fourth driven component 317 drive the passive disc 308 to rotate clockwise. At this time, the cylinder 309 on the first driven component 314 and the second driven component 315 does not exert force on the corresponding triangular plate 319.

[0059] It should be noted that, in this embodiment, the number of driven components can also be set to other numbers, such as two groups, three groups, six groups or other numbers, as long as the number of cylinders 309 is equal to the number of driven components, and the cylinders 309 can drive the driven components to move.

[0060] Further, such as Figure 1 , 7As shown in FIG. 8 , the transmission mechanism further includes a forward ratchet 324 and a reverse ratchet 325 disposed between the active disc 307 and the passive disc 308. The forward ratchet 324 is disposed close to the active disc 307. Both the forward ratchet 324 and the reverse ratchet 325 are fixedly connected to the upper platform 1. In this embodiment, a ratchet sleeve 326 is sleeved outside the forward ratchet 324 and the reverse ratchet 325. The ratchet sleeve 326 is fixedly connected to the upper platform 1 via a fixing rod 327. The structure of the ratchet sleeve 326 is a prior art and will not be described in detail in this embodiment. Figure 7 As shown, the triangular plates 319 in the two adjacent groups of driven assemblies on the passive disc 308 are provided with first pawls 328 that mesh with the positive ratchet 324, that is, the ends of the pads 321 in the first driven assembly 314 and the second driven assembly 315 are fixed with first pawls 328, and the first pawls 328 are used to limit the counterclockwise rotation of the passive disc 308, and the hypotenuses of the triangular plates 319 in the first driven assembly 314 and the second driven assembly 315 are both against the cylinder 309, and the abutment here means that when the active disc 307 rotates counterclockwise, the cylinder 309 can squeeze the triangular plate 319 to move toward the center of the passive disc 308, and the first pawl 328 is separated from the positive ratchet 324 and is in an unlocked state, and the passive disc 308 can rotate counterclockwise at this time. In addition, the triangular plates 319 in the two adjacent groups of driven assemblies are provided with second pawls 329 meshing with the reverse ratchet 325, that is, the ends of the pads 321 in the third driven assembly 316 and the fourth driven assembly 317 are fixed with second pawls 329, which are used to limit the clockwise rotation of the passive disc 308.

[0061] It should be noted that the two first ratchets 328 are used to limit the counterclockwise rotation of the passive disc 308, and the two second ratchets 329 will not limit the counterclockwise rotation of the passive disc 308. When the active disc 307 rotates counterclockwise, the cylinder 309 pushes the triangular plate 319 in the first driven component 314 and the second driven component 315 to move toward the center, and the two first ratchets 328 are separated and unlocked from the positive ratchet 324, and the passive disc 308 can rotate counterclockwise. The two second ratchets 329 are used to limit the clockwise rotation of the passive disc 308, and the two first ratchets 328 will not limit the clockwise rotation of the passive disc 308. When the active disc 307 rotates clockwise, the cylinder 309 pushes the triangular plate 319 in the third driven component 316 and the fourth driven component 317 to move toward the center, and the two second ratchets 329 are separated and unlocked from the reverse ratchet 325, and the passive disc 308 can rotate clockwise.

[0062] In this embodiment, the positive ratchet 324 and the reverse ratchet 325 are provided to prevent the passive disc 308 from actively rotating, which has the characteristic of reducing the multi-drive on the moving pair.

[0063] The Archimedean spiral plate 303 is detachably mounted on the output shaft of the passive disc 308. Figure 2 , 4 As shown, a transmission shaft 330 is fixedly disposed at the bottom of the passive disc 308. The transmission shaft 330 is the output shaft of the passive disc 308. The Archimedean spiral plate 303 is sleeved on the transmission shaft 330. Figure 3-6 As shown, in this embodiment, the Archimedean spiral plate 303 includes an upper plate 3031 and a lower plate 3032 which are arranged at intervals. A first connecting block 3034 is fixedly arranged at the center of the upper plate 3031. The first connecting block 3034 is detachably connected to the transmission shaft 330 through a fastener. A second connecting block 3035 is fixedly arranged at the center of the lower plate 3032. The second connecting block 3035 has the same structure as the first connecting block 3034. The second connecting block 3035 is also detachably connected to the transmission shaft 330 through a fastener. The fastener here refers to a bolt. When the upper plate 3031 needs to be driven to rotate by the passive disc 308, the bolt on the first connecting block 3034 is screwed into the transmission shaft 330, and the upper plate 3031 will rotate with the transmission shaft 330; when the upper plate 3031 and the lower plate 3032 need to rotate together with the passive disc 308, the bolts on the first connecting block 3034 and the second connecting block 3035 are screwed into the transmission shaft 330.

[0064] The Archimedean screw plate 303 is provided with a plurality of spiral grooves 3033, the number of which is equal to the number of the first connecting rods 304, and a first connecting rod 304 is slidably clamped in each spiral groove 3033. In this embodiment, there are six first connecting rods 304, and there are also six spiral grooves 3033. Figure 6 As shown, four spiral grooves 3033 are provided on the upper plate 3031, two spiral grooves 3033 are provided on the lower plate 3032, and a sliding rod 331 is fixed on the first connecting rod 304, and the sliding rod 331 is slidably clamped in the spiral groove 3033, see Figure 3 In this embodiment, the upper plate 3031 and the lower plate 3032 are arranged at intervals, wherein the two first connecting rods 304 are clamped in the two spiral grooves 3033 of the lower plate 3032 through the sliding rods 331, and the sliding rods 331 pass through the two spiral grooves 3033 of the lower plate 3032 and extend between the lower plate 3032 and the upper plate 3031. The sliding rods 331 fixed on the other four first connecting rods 304 are clamped in the four spiral grooves 3033 of the upper plate 3031, and the positions on the lower plate 3032 corresponding to the spiral grooves 3033 of the upper plate 3031 are set as hollow structures, see Figure 6, so that the sliding rod 331 passes through the lower plate 3032 and extends into the spiral groove 3033 of the upper plate 3031. The starting point of the spiral groove 3033 is close to the transmission shaft 330, and the end point is close to the edge of the lower plate 3032 or the upper plate 3031. The Archimedean spiral plate 303 rotates to drive the first connecting rod 304 to make a linear motion along the radial direction of the Archimedean spiral plate 303.

[0065] The number of the first slide rails 306, the number of the first slide assemblies and the number of the first connecting rods 304 are equal, all of which are six. Figure 2 As shown, a first sliding assembly is fixed on each first connecting rod 304, and a first sliding assembly is slidably arranged on each first slide rail 306. Specifically, six first slide rails 306 are fixed at the bottom end of the upper platform 1 and are distributed at intervals along the circumference of the upper platform 1. The first sliding assembly includes a fixed block 332 and a slider 305. The fixed block 332 is fixedly connected to the first connecting rod 304. The slider 305 is fixed at the top of the fixed block 332. The slider 305 is slidably arranged on the first slide rail 306. The structure of the first slide rail 306 and the slider 305 is the prior art and will not be described in detail here. When the first connecting rod 304 moves linearly toward the center along the radial direction of the Archimedean spiral plate 303, the slider 305 moves toward the center of the upper platform 1 along the first slide rail 306, thereby driving the variable stiffness joint 4 to move toward the center position.

[0066] It should be noted that, in this embodiment, the number of the first slide rails 306 , the number of the first sliding components, and the first connecting rods 304 can be adjusted according to actual needs.

[0067] In this embodiment, the variable stiffness characteristic can be achieved through structures such as the active disc 307, the passive disc 308, the spring guide support column 310, and the spring 323. The active rotation of the passive disc 308 can be avoided through the positive ratchet 324, the reverse ratchet 325, the first pawl 328, and the second pawl 329. Of course, the Archimedean spiral 303 can also be directly connected to the output end of the first rotating drive element 301, so that the first rotating drive element 301 drives the Archimedean spiral 303 to rotate.

[0068] 2. Variable stiffness joint 4;

[0069] like Figure 1 , 11As shown, there are multiple variable stiffness joints 4, and the number is equal to the number of the first connecting rods 304. In this embodiment, the number of variable stiffness joints 4 is also six. Each variable stiffness joint 4 includes a ball joint 41, a telescopic rod 42, a sleeve 43, a second connecting rod 44 and a Hooker's joint 45 connected in sequence. The ball joint support is fixedly connected to the first connecting rod 304, the ball body of the ball joint is fixedly connected to the telescopic rod 42, the telescopic rod 42 is movably arranged in the sleeve 43, the second connecting rod 44 and the telescopic rod 42, and the second connecting rod 44 and the first connecting rod 304 are all hinged, and the second connecting rod 44, the telescopic rod 42, and the first connecting rod 304 form a triangle. The Hooke hinge 45 is fixedly arranged at the bottom of the sleeve 43, and the Hooke hinge 45 is fixedly connected to the second sliding assembly; when the Archimedean spiral plate 303 rotates, the first connecting rod 304 moves linearly along the radial direction of the Archimedean spiral plate 303. Since the second connecting rod 44 is hingedly connected to the first connecting rod 304, the movement of the first connecting rod 304 causes the telescopic rod 42 to extend or retract from the sleeve 43. Compared with the prior art in which an electric push rod is added to control the extension and retraction of the telescopic rod 42, this structure can reduce the drive, reduce the cost, and is simple to operate; at the same time, this structure also has the advantages of high positioning accuracy and strong bearing capacity. In addition, in this embodiment, a positive ratchet 324 and a reverse ratchet 325 are provided to prevent the passive disc 308 from actively rotating, and also to prevent the telescopic rod 42 from actively retracting into the sleeve 43.

[0070] The structures of the Hooke's joint 45 and the ball joint 41 are both prior art, and their structures and working principles will not be described in detail.

[0071] 3. The second variable stiffness module 5;

[0072] like Fig.12 As shown, the second variable stiffness module 5 includes a driving mechanism, a circumferential elastic sheet 501 , a plurality of second sliding components and a plurality of second sliding rails 502 disposed on the circumferential elastic sheet 501 .

[0073] like Fig.13 As shown, a support column 503 is provided between the circumferential spring piece 501 and the lower platform 2. In this embodiment, the circumferential spring piece 501 is made of 45# steel plate, which is equivalent to a free cantilever beam. When the second sliding component moves, the circumferential spring piece 501 is deformed by force, thereby achieving variable stiffness. 45# steel has the characteristic of generating a large elastic force under a small deformation, so the use of the circumferential spring piece 501 enables the present invention to have a large output torque.

[0074] like Fig.12As shown, in this embodiment, the number of the second slide rails 502 and the second sliding assembly are both six, and of course the number can be adjusted according to actual needs. The six second slide rails 502 are arranged on the circumferential spring sheet 501 at intervals along the circumference thereof, and the length direction of the second slide rails 502 is arranged along the radial direction of the circumferential spring sheet 501, and a second sliding assembly is slidably arranged on each second slide rail 502.

[0075] The second sliding assembly includes a screw 504 rotatably arranged on the circumferential spring piece 501 and a screw seat 505 threadedly sleeved on the screw 504. The screw seat 505 is axially arranged along the radial direction of the circumferential spring piece 501. The bottom of the screw seat 505 is slidably clamped on the second slide rail 502, and the Hooke's hinge 45 is fixedly connected to the screw seat 505.

[0076] The driving mechanism drives the second sliding assembly to perform linear motion in a direction close to or away from the center of the circumferential spring sheet 501. Specifically, the driving mechanism is fixed on the lower platform 2 through a bracket, and the driving mechanism includes a second rotating driving element 506 and a transmission assembly, the input end of the transmission assembly is connected to the output end of the second rotating driving element 506, and the output end of the transmission assembly is connected to the lead screw 504. The second rotating driving element 506 drives the lead screw 504 to rotate through the transmission assembly to make the lead screw seat 505 perform linear motion along the radial direction of the circumferential spring sheet 501. In this embodiment, the second rotating driving element 506 is a stepping motor, and the transmission assembly includes a first synchronous pulley 507, a plurality of second synchronous pulleys 508, a synchronous belt 509, a plurality of stepped shafts 510, and a plurality of bevel gear sets 511; the number of the second synchronous pulleys 508, the number of the stepped shafts 510, and the number of the bevel gear sets 511 are equal to the number of the second slide rails 502, which are all six. The first synchronous pulley 507 is fixed on the output shaft of the stepper motor, and the first synchronous pulley 507 and the second synchronous pulley 508 are driven by the synchronous belt 509. The stepped shaft 510 is fixed on the second synchronous pulley 508. The rotation axes of the first synchronous pulley 507 and the second synchronous pulley 508 are parallel to the axial direction of the stepped shaft 510. The input end of the bevel gear set 511 is connected to the stepped shaft 510, and the output end of the bevel gear set 511 is connected to the lead screw 504. The working principle is as follows: the second rotary drive element 506 rotates, the first synchronous pulley 507 rotates, the synchronous belt 509 rotates to drive the second synchronous pulley 508 to rotate, so that the bevel gear set 511 rotates to drive the lead screw 504 to rotate. At this time, the lead screw seat 505 has a tendency to rotate with the lead screw 504, but because the bottom of the lead screw seat 505 is stuck on the second slide rail 502, it can only move along the axial direction of the lead screw 504. At this time, the Hooke hinge 45 and the variable stiffness joint 4 move along the axial direction of the lead screw 504. After the movement, the position of the second sliding component on the circumferential spring piece 501 will change, the force point of the circumferential spring piece 501 will change, and the rigidity will also change.

[0077] Of course, in this embodiment, six stepper motors can also be used to drive the bevel gear set 511 to rotate respectively. Compared with this structure, this embodiment can reduce the use of motors and reduce costs.

[0078] Further, such as Fig.12 , 14 As shown, the second sliding assembly is provided with an unfolding mechanism 512, and the unfolding mechanism 512 includes two hinges 513, and each hinge 513 includes a plurality of connecting rods 514. In this embodiment, each hinge 513 includes six connecting rods 514, and each connecting rod 514 includes a first straight rod 5141 and a second straight rod 5142 that are fixedly connected. The angle formed by the first straight rod 5141 and the second straight rod 5142 is an obtuse angle, and the six connecting rods 514 are hingedly connected end to end to form a ring structure; the two hinges 513 are cross-arranged up and down, and the overlapping positions of the two hinges 513 are hingedly connected; the two hinges 513 are hingedly connected to the second sliding assembly at the positions corresponding to the second sliding assembly. Specifically, the six connecting rods 514 are hingedly connected end to end through shafts and bearings, and are more flexible when rotating. This structure is a prior art and will not be described in detail in this embodiment. The overlapping position of the two hinges 513 is the corner of the connecting rod 514, which is hingedly connected through a hinge shaft. It should be noted that the shaft, the bearing, and the hinge shaft are connected at the same time. Fig.12 , 14 A suspension rod rotation pair 5143 is provided on the lead screw seat 505 at positions corresponding to the two hinges 513 , and the two hinges 513 are hingedly connected to the lead screw seat 505 via the suspension rod rotation pair 5143 .

[0079] When the screw seat 505 moves axially along the screw 504, the two hinges 513 shrink inward or expand outward. This structure can buffer the movement of the screw 504 and the variable stiffness joint 4, making their movement smoother and increasing the stability and accuracy of the variable stiffness.

[0080] The present embodiment has the following advantages: first, the variable stiffness structure is formed by using the active disc 307, the passive disc 308, the Archimedean spiral plate 303, the unfolding mechanism 512, the lead screw 504 and the transmission assembly, which has a simple and reliable structure, a small volume, and can achieve the effect of variable stiffness in both forward and reverse driving; second, the circumferential spring piece 501 is used, which has the characteristics of small deformation and can generate large elastic force, so that the present invention has a large output torque; third, the structure of the stepping motor, the first synchronous pulley 507, the second synchronous pulley 508, the synchronous belt 509, the bevel gear set 511 and the like can realize the rapid displacement of the second sliding assembly, and the Archimedean spiral plate 303 can realize the rapid displacement of the first sliding assembly, which reduces the number of drivers as a whole, has a simple structure and a rapid response; fourth, by using the circumferential spring pieces 501 with different elasticity or selecting the bevel gear set 511 with different moduli, different stiffness characteristics and different output torques can be obtained, thereby meeting different stiffness characteristic requirements.

[0081] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the above embodiment, those skilled in the art can still modify the technical solutions described in the above embodiment or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A compliant robot based on changing the force of a circumferential spring, characterized in that: It includes an upper platform, a first variable stiffness module, a variable stiffness joint, a second variable stiffness module and a lower platform; The first variable stiffness module includes a first rotation drive element, an Archimedean spiral plate, a plurality of first connecting rods, a plurality of first sliding assemblies, and a plurality of first sliding rails; The first rotating driving element is fixed on the upper platform, the Archimedean spiral plate is connected to the output end of the first rotating driving element, a plurality of spiral grooves are provided on the Archimedean spiral plate, the number of the spiral grooves is equal to the number of the first connecting rods, a first connecting rod is slidably clamped in each spiral groove, the Archimedean spiral plate rotates to drive the first connecting rod to perform linear motion along the radial direction of the Archimedean spiral plate; the number of the first slide rails and the number of the first sliding assemblies are equal to the number of the first connecting rods, a first sliding assembly is fixed on each first connecting rod, and a first sliding assembly is slidably arranged on each first slide rail; The second variable stiffness module includes a driving mechanism, a circumferential spring sheet, a plurality of second sliding components and a plurality of second sliding rails arranged on the circumferential spring sheet; A support column is arranged between the circumferential spring sheet and the lower platform, a plurality of second slide rails are arranged on the circumferential spring sheet at intervals along the circumference thereof, the length direction of the second slide rails is arranged along the radial direction of the circumferential spring sheet, and a second slide assembly is slidably arranged on each second slide rail; the driving mechanism drives the second slide assembly to perform linear motion in a direction close to or away from the center of the circumferential spring sheet; There are multiple variable stiffness joints, and their number is equal to the number of first connecting rods. Each variable stiffness joint includes a ball joint, a telescopic rod, a sleeve, a second connecting rod and a Hook's joint connected in sequence. The ball joint support is fixedly connected to the first connecting rod, the ball joint ball is fixedly connected to the telescopic rod, the telescopic rod is movably arranged in the sleeve, and the second connecting rod and the telescopic rod, as well as the second connecting rod and the first connecting rod are all hinged; the Hook's joint is fixedly arranged at the bottom of the sleeve, and the Hook's joint is fixedly connected to the second sliding assembly.

2. The compliant robot based on changing the force of the circumferential spring sheet according to claim 1, characterized in that: The first variable stiffness module also includes a transmission mechanism, which is located between the upper platform and the Archimedean spiral plate; the transmission mechanism includes an active disc and a passive disc; the active disc is fixedly connected to the output end of the first rotating drive element, a spring guide support column is fixedly provided at the center of the passive disc, and the spring guide support column is movably connected to the active disc; the Archimedean spiral plate is detachably sleeved on the output shaft of the passive disc; A plurality of cylinders are fixed at the bottom end of the active disc; a plurality of groups of driven components are arranged on the passive disc, and the plurality of groups of driven components are arranged at intervals along the circumference of the passive disc, and the driven components include two constraint plates fixed in parallel on the passive disc, a triangular plate is slidably arranged between the two constraint plates, the cylinder extends into a groove surrounded by the triangular plate and the two constraint plates, the hypotenuse of the triangular plate is arranged close to the cylinder, a guide column is arranged on the spring guide support column facing the triangular plate, the triangular plate is slidably arranged on the guide column, a spring is sleeved on the guide column, one end of the spring is fixedly connected to the triangular plate, and the other end is fixedly connected to the spring guide support column; the number of cylinders is equal to the number of driven components.

3. The compliant robot based on changing the force of the circumferential spring sheet according to claim 2, characterized in that: The transmission mechanism also includes a forward ratchet and a reverse ratchet arranged between the active disc and the passive disc, the forward ratchet being arranged close to the active disc, and both the forward ratchet and the reverse ratchet being fixedly connected to the upper platform; the driven components are provided with four groups, and the triangular plates in two adjacent groups of driven components are provided with a first pawl meshing with the forward ratchet, and the hypotenuses of the triangular plates in the two groups of driven components are both against the cylinder; in addition, the triangular plates in the two adjacent groups of driven components are provided with a second pawl meshing with the reverse ratchet; The first ratchet is used to limit the passive disc to rotate counterclockwise, and the second ratchet is used to limit the passive disc to rotate clockwise.

4. The compliant robot based on changing the force of the circumferential spring sheet according to claim 3, characterized in that: The number of the first connecting rods is six, the Archimedean spiral plate comprises an upper plate and a lower plate which are arranged at intervals, the upper plate is provided with four spiral grooves, the lower plate is provided with two spiral grooves, the position of the lower plate corresponding to the spiral groove of the upper plate is provided with a hollow structure, the six first connecting rods are respectively slidably clamped in a spiral groove, and the Archimedean spiral plate rotates to drive the first connecting rods to perform linear motion along the radial direction of the Archimedean spiral plate; A transmission shaft is fixedly arranged at the bottom of the passive disc, and the transmission shaft is the output shaft of the passive disc. The Archimedean spiral plate is sleeved on the transmission shaft. A first connecting block is fixedly arranged on the upper plate, and the first connecting block is detachably connected to the transmission shaft through a fastener. A second connecting block is fixedly arranged on the lower plate, and the second connecting block is also detachably connected to the transmission shaft through a fastener.

5. The compliant robot based on changing the force of the circumferential spring sheet according to any one of claims 1 to 4, characterized in that: The second sliding assembly includes a screw rotatably arranged on the circumferential spring sheet and a screw seat threadedly sleeved on the screw, the screw seat is axially arranged along the radial direction of the circumferential spring sheet, and the screw seat is slidably clamped on the second slide rail; The driving mechanism is fixed on the lower platform, and the driving mechanism includes a second rotating driving element and a transmission assembly. The input end of the transmission assembly is connected to the output end of the second rotating driving element, and the output end of the transmission assembly is connected to the screw. The second rotating driving element drives the screw to rotate through the transmission assembly so that the screw seat performs a linear motion along the radial direction of the circumferential spring sheet.

6. The compliant robot based on changing the force of the circumferential spring sheet according to claim 5, characterized in that: The second rotating driving element is a stepping motor, and the transmission assembly includes a first synchronous pulley, multiple second synchronous pulleys, a synchronous belt, multiple stepped shafts and multiple bevel gear sets; the number of second synchronous pulleys, the number of stepped shafts, the number of bevel gear sets is equal to the number of second slide rails, the first synchronous pulley is fixed on the output shaft of the stepping motor, the first synchronous pulley and the second synchronous pulley are driven by a synchronous belt, the stepped shaft is fixed on the second synchronous pulley, the rotation axis of the first synchronous pulley and the second synchronous pulley is parallel to the axial direction of the stepped shaft, the input end of the bevel gear set is connected to the stepped shaft, and the output end of the bevel gear set is connected to the lead screw.

7. The compliant robot based on changing the force of the circumferential spring sheet according to any one of claims 1 to 4 and 6, characterized in that: The second sliding assembly is provided with an unfolding mechanism, which includes two hinges, each hinge includes a plurality of connecting rods, the connecting rods include a first straight rod and a second straight rod which are fixedly connected, the angle formed by the first straight rod and the second straight rod is an obtuse angle, and the plurality of connecting rods are hingedly connected end to end to form a ring structure; the two hinges are cross-arranged up and down, the overlapping positions of the two hinges are hingedly connected, and the two hinges are hingedly connected to the second sliding assembly at positions corresponding to the second sliding assembly.

8. The compliant robot based on changing the force of the circumferential spring sheet according to claim 7, characterized in that: The circumferential spring piece is made of 45# steel plate.

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