Variable stiffness hybrid elastic drive based on variable stiffness planetary gear reducer unit

Abstract

The present invention discloses a variable stiffness hybrid elastic driver based on a variable stiffness planetary gear reducer unit. The variable stiffness motor mounting frame of the variable stiffness planetary gear reducer unit is connected to the outer sleeve of the drive motor at the input motor end. The inner ring gear positioning frame at the input motor end is connected to the inner ring gear of the variable stiffness planetary gear reducer unit. The lower end of the sun gear of the variable stiffness planetary gear reducer unit is inserted into the middle hole of the sun gear drive end at the input motor end. The lead screw of the variable stiffness planetary gear reducer unit is inserted into the inner hole of the flange bearing at the input motor end. The driver housing of the protective housing is connected to the outer sleeve of the motor. The driver cover of the protective housing presses the planet carrier bearing of the variable stiffness planetary gear reducer unit. The raised steel balls of the steel ball linear bearing of the variable stiffness planetary gear reducer unit are tangent to the conical groove on the inner wall of the driver housing. The present invention has the advantages of being able to absorb external impact and vibration, achieving high energy efficiency, and increasing torque output.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field, and in particular to a variable stiffness hybrid elastic driver based on a variable stiffness planetary gear reducer unit. BACKGROUND

[0002] Biology in nature exhibits amazing adaptability, and can perform diversified tasks in a changing environment. This adaptability is largely due to the coordinated work of muscle and joint systems, which can adjust the stiffness in real time to adapt to different motion requirements. Specifically, the joint can increase the stiffness through muscle adjustment when performing tasks such as jumping that require stability and greater power output; the joint can reduce the stiffness when performing tasks such as landing that require shock absorption and energy storage. This dynamic adjustment mechanism is the result of the high complexity and fine regulation of the biological motion system. Inspired by this natural muscle and joint stiffness adjustment mechanism, people invented variable stiffness drivers.

[0003] Traditional rigid drivers have the characteristics of simple control, high precision, and infinite theoretical stiffness. With the development of robot technology, traditional rigid drivers have been unable to meet the needs. For example, various impacts often occur when the robot moves, and there is no energy absorption and buffer structure in the rigid driver, so the instantaneous impact force can easily cause damage to the structure of the robot. The introduction of variable stiffness drivers in these application scenarios can effectively solve these problems. Variable stiffness drivers can make joint motion smoother, not only preventing hardware damage caused by impact, but also constantly storing and releasing energy during robot walking to achieve higher energy efficiency.

[0004] By integrating flexible mechanical components with variable stiffness characteristics into the driver in series or parallel, it is a simple and effective solution to realize a variable stiffness driver. Existing variable stiffness drivers can be divided into series and parallel types according to their structure, and can be divided into variable stiffness based on spring pre-tightening, variable stiffness based on lever principle, variable stiffness based on changing the effective length of elastic elements, etc. according to their variable stiffness principle. The existing variable stiffness drivers have their own advantages and disadvantages, and they can perform well in their own applicable scenarios; however, they cannot fully meet all the technical specifications of the ideal driver in actual applications: compact and simple mechanical design, no motion range limitation, wide stiffness adjustment range, rapid stiffness change, high energy efficiency drive. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a variable stiffness hybrid elastic driver based on a variable stiffness planetary gear reducer unit, which combines the advantages of variable stiffness series elastic drivers and variable stiffness parallel elastic drivers, and complements the disadvantages, and can better meet the technical specification requirements of the ideal variable stiffness driver.

[0006] The present application is achieved by the following technical means to achieve the above technical purposes.

[0007] The variable stiffness hybrid elastic driver based on the variable stiffness planetary gear reducer unit comprises a protective shell, a variable stiffness planetary gear reducer unit and an input motor end;

[0008] The variable stiffness planetary gear reducer unit comprises a planet carrier, a sun gear, a planet carrier bearing, planet shafts, an inner ring gear, a spring mounting frame, springs, steel ball linear bearings, a variable stiffness motor, a variable stiffness motor end gear, a slotted connecting rod, a lead screw nut, a lead screw, a lead screw end gear and planet gears; the planet carrier bearing, the inner ring gear and the spring mounting frame are sequentially arranged, and the planet carrier is coaxially arranged inside the planet carrier bearing; the sun gear is rotatably arranged in the middle of the planet carrier at the upper end and is inserted into the middle of the sun gear driving end of the input motor end at the lower end; one end of each of the three planet shafts is fixed to the planet carrier, and the other end of each of the three planet shafts is fixed to the inside of a planet gear; the planet gear is matched with the inner wall of the inner ring gear; the inner ring gear and the spring mounting frame are matched through a sliding block sliding rail; a plurality of tracks are arranged on the outer side of the spring mounting frame, each track is matched with a steel ball linear bearing, and a spring is arranged between the spring mounting frame and the steel ball linear bearing; the variable stiffness motor is arranged on the variable stiffness motor mounting frame, and the output end of the variable stiffness motor is fixed through the middle hole of the variable stiffness motor end gear; one end of the lead screw is matched with the lead screw nut, then passes through the variable stiffness motor mounting frame, and is fixedly connected with the lead screw end gear; the other end of the lead screw is inserted into the inner hole of the flange bearing of the input motor end; the lead screw nut is connected with the lead screw nut connecting piece, the round hole of the lead screw nut connecting piece is matched with the round hole side of the slotted connecting rod, and is penetrated through a plug screw; the notch side of the slotted connecting rod is matched with the round hole on the spring mounting frame, and is also penetrated through a plug screw;

[0009] The inner ring gear is connected with the inner ring gear positioning frame of the input motor end.

[0010] The convex steel ball of the steel ball linear bearing is tangentially matched with the conical groove on the inner wall of the driver shell of the protective shell.

[0011] In the above technical solution, the protective shell is connected by the driver cover plate and the driver shell.

[0012] In the above technical solution, the input motor end comprises a driving motor, the driving motor is connected with a driving motor sleeve, the flange bearing is embedded in the driving motor sleeve; the output end of the driving motor is connected with the sun gear driving end, the sun gear driving end is embedded with a sun gear driving end bearing on the outer side, one end of the sun gear driving end bearing is attached to the flange of the sun gear driving end, and the other end is pressed by a screw.

[0013] The driver shell is connected with the motor sleeve together, and the driver cover plate presses the planet carrier bearing.

[0014] The variable stiffness motor mounting frame is connected with the driving motor sleeve together.

[0015] The inner ring gear positioning frame is pressed tightly with the sun gear driving end bearing at one end close to the driving motor sleeve.

[0016] The sun gear is installed in the inner hole of the sun gear bearing, and the sun gear bearing is embeddedly installed in the through hole in the middle of the planet carrier.

[0017] The inner ring gear is uniformly provided with a plurality of sliding rails on the outer side, the spring mounting frame is uniformly provided with a plurality of sliding blocks on the inner side, and the sliding blocks slide along the sliding rails.

[0018] The track is composed of two optical axes, and the steel ball linear bearing moves along the optical axis in the axial direction.

[0019] The planet shaft is fixed by the gasket and the snap spring at both ends.

[0020] The beneficial effects of the present application are:

[0021] (1) The variable stiffness elastic mechanism (the part of the variable stiffness planetary gear reducer unit except the planetary gear reducer, the planetary gear reducer including the planet carrier, the sun gear bearing, the sun gear, the planet carrier bearing, the planet shaft and the inner ring gear) is introduced into the structure design between the inner ring gear of the planetary gear reducer and the fixed end of the driver (protective shell), the flexibility is introduced into the driver, the driver has the ability to absorb external impact and protect the driver, and the ability to store elastic potential energy in motion and improve energy efficiency.

[0022] (2) The variable stiffness structure is introduced between the inner ring gear and the fixed end of the driver, so that the driver simultaneously realizes the characteristics of series elastic drive (such as absorbing external impact and vibration, high energy efficiency, balancing position arbitrary adjustment, human-computer interaction safety, etc.) and parallel elastic drive (such as high output torque, high energy efficiency, etc.) and variable stiffness (such as high working bandwidth, strong adaptability, outstanding bionics, etc.), which enriches the application scenarios of the driver and solves the problem that the series or parallel elastic drive itself cannot meet all the technical specifications of the ideal variable stiffness drive.

[0023] (3) The present application adjusts the screw nut to change the curvature of the tangent position of the steel ball and the conical groove, realizes variable stiffness, has the characteristics of low energy consumption to realize variable stiffness and zero energy consumption to maintain stiffness, and the conical groove can be customized according to the stiffness requirement. Theoretically, the stiffness adjustment range can be from a certain value greater than zero to infinity. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The variable stiffness mixed elastic driver assembly schematic diagram of the present application is shown.

[0025] Figure 2 The variable stiffness mixed elastic driver explosion schematic diagram of the present application is shown.

[0026] Figure 3(a) is a schematic diagram of the protective shell structure of the present application;

[0027] Figure 3(b) is a rear view of the protective shell of the present application;

[0028] Figure 4(a) is a schematic diagram of the variable stiffness planetary gear reducer unit structure of the present application;

[0029] Figure 4(b) is a bottom view of the variable stiffness planetary gear reducer unit of the present application;

[0030] Figure 5 The input motor end assembly diagram of the present application is shown.

[0031] In the figure: 1-protective shell, 2-variable stiffness planetary gear reducer unit, 3-input motor end, 4-driver cover plate, 5-M3 countersunk head screw, 6-driver shell, 7-carrier, 8-sun gear bearing, 9-sun gear, 10-carrier bearing, 11-planet shaft, 12-8mm circlip, 13-8mm spacer, 14-inner ring, 15-rail, 16-M2 screw, 17-sliding block, 18-spring mounting bracket, 19-spring, 20-3mm optical axis, 21-steel ball linear bearing, 22-variable stiffness motor, 23-variable stiffness motor mounting bracket, 24-M3 flat head screw, 25-screw nut connecting piece, 26-variable stiffness motor end gear, 27-grooved connecting rod, 28-screw nut, 29-screw, 30-bolt, 31-screw end gear, 32-M3 spacer, 33-planet wheel, 34-flange bearing, 35-driving motor outer sleeve, 36-sun gear driving end bearing, 37-inner ring positioning bracket, 38-M4 screw, 39-sun gear driving end, 40-M2.5 screw, 41-M2 flat head screw, 42-bearing pressing ring, 43-driving motor, 44-M3 screw, 45-conical groove. DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the drawings and specific embodiments, but the scope of protection of the application is not limited thereto.

[0033] As Figure 1 , 2 , 3(a), 3(b), 4(a), 4(b), 5, the variable stiffness hybrid elastic driver based on the variable stiffness planetary gear reducer unit of the application is composed of a protective shell 1, a variable stiffness planetary gear reducer unit 2 and an input motor end 3. The variable stiffness motor mounting bracket 23 of the variable stiffness planetary gear reducer unit 2 is connected together with the drive motor outer sleeve 35 of the input motor end 3 through M3 screws 44. The M2.5 screws 40 pass through the reserved holes of the inner ring gear positioning bracket 37 of the input motor end 3 and are connected together with the inner ring gear 14 of the variable stiffness planetary gear reducer unit 2. The driver shell 6 of the protective shell 1 is connected together with the motor outer sleeve 35 of the input motor end 3 through M3 screws 44, and the driver cover plate 4 of the protective shell 1 presses the planet carrier bearing 10 of the variable stiffness planetary gear reducer unit 2. The convex steel balls of the three steel ball linear bearings 21 of the variable stiffness planetary gear reducer unit 2 are tangent to the conical grooves 45 on the inner wall of the driver shell 6 of the protective shell 1. The D-shaped shaft at the lower end of the sun gear 9 of the variable stiffness planetary gear reducer unit 2 is inserted into the middle D-shaped hole of the sun gear drive end 39 of the input motor end 3. The lower end of the lead screw 29 of the variable stiffness planetary gear reducer unit 2 is inserted into the inner hole of the flange bearing 34 of the input motor end 3.

[0034] As Figure 3(a) , 3(b) shown, the assembly diagram of the protective shell 1, the driver cover plate 4 and one side of the driver shell 6 are connected together through ten M3 countersunk head screws 5.

[0035] As Figure 4(a) , 4(b)As shown, the assembly diagram of the variable stiffness planetary gear reducer unit 2, the planetary carrier bearing 10 is coaxial with the planetary carrier 7, and the planetary carrier bearing 10 is embedded with the outer wall of the planetary carrier 7; The sun gear bearing 8 is embedded in the through hole in the middle of the planetary carrier 7; The protruding shaft on the upper part of the sun gear 9 is installed in the inner hole of the sun gear bearing 8; One end of the three planetary shafts 11 passes through the reserved hole of the planetary carrier 7, and is fixed through the 8mm spacer 13 and the 8mm snap spring 12, and the other end of the planetary shaft 11 passes through the planetary gear 33, and is also fixed through the 8mm spacer 13 and the 8mm snap spring 12; The inner ring 14 is geared together with the three planetary gears 33; Three slide rails 15 are evenly distributed and installed on the outside of the inner ring 14, and each slide rail 15 is fixed on the inner ring 14 by two M2 screws 16; Three sliders 17 are installed on the inside of the spring mounting bracket 18, and each slider 17 is fixed by two M2 screws 16, and the three sliders 17 are matched together with the three slide rails 15 and can move along the slide rails 15; Six 3mm optical shafts 20 are inserted into the reserved holes of the spring mounting bracket 18, and each 3mm optical shaft 20 is fixed by an M2 screw 16 to form three groups of tracks; Three steel ball linear bearings 21 are matched together with the three groups of tracks, and the steel ball linear bearings 21 can freely move along the axial direction of the 3mm optical shaft 20; The spring 19 is embedded between the spring mounting bracket 18 and the steel ball linear bearing 21; The lead screw nut 28 is matched together with the lead screw 29, and when the lead screw 29 rotates, the lead screw nut 28 will move up and down along the lead screw 29; One end of the lead screw 29 passes through the variable stiffness motor mounting bracket 23, passes through the lead screw end gear 31, and connects the lead screw end gear 31 and the lead screw 29 together through the M3 spacer 32 and the M3 flat head screw 24; The variable stiffness motor 22 is installed on the variable stiffness motor mounting bracket 23 by three M3 screws 24; The output end of the variable stiffness motor 22 passes through the middle hole of the variable stiffness motor end gear 26, is connected together through the M3 spacer 32 and the M3 flat head screw 24, and is fixed on the shaft side by an M3 flat head screw 24; The lead screw nut connecting piece 25 is connected together with the lead screw nut 28 by four M3 flat head screws 24; The round hole side of the slotted connecting rod 27 is matched with the round hole of the lead screw nut connecting piece 25, and is penetrated by a set bolt 30, and the slotted connecting rod 27 can freely rotate around the set bolt 30; The slot side of the slotted connecting rod 27 is matched with the round hole on the spring mounting bracket 18, and is also penetrated by a set bolt 30, and the slotted connecting rod 27 is matched with the set bolt 30 through the slot.

[0036] As Figure 5As shown, the assembly diagram of the input motor end 3, the driving motor 43 is connected with the driving motor outer sleeve 35 through ten M2.5 screws 40; the sun gear driving end 39 is connected with the output end of the driving motor 43 through three M4 screws 38; the inner wall of the sun gear driving end bearing 36 is embedded in the outer wall of the sun gear driving end 39, one end of the sun gear driving end bearing 36 is attached to the flange of the sun gear driving end 39, and the other end is pressed by six M3 flat head screws 24; the inner tooth ring positioning frame 37 is concentrically installed on the inner tooth ring 14, and the end of the inner tooth ring positioning frame 37 close to the driving motor outer sleeve 35 is pressed by the bearing pressing ring 42 and eight M2 flat head screws 41 and the sun gear driving end bearing 36; the flange bearing 34 is embedded in the reserved hole of the driving motor outer sleeve 35.

[0037] The working principle of the variable stiffness hybrid elastic driver based on the variable stiffness planetary gear reducer unit is:

[0038] The variable stiffness principle: the rotation of the variable stiffness motor 22 can make the spring mounting frame 18 indirectly matched with the lead screw nut 28 move axially along the lead screw 29, so as to change the matching position of the steel ball linear bearing 21 and the conical groove 45, that is, the curvature of the tangent matching surface of the steel ball is changed, and the variable stiffness adjustment is realized. The conical surface of the groove can be customized according to the requirements, so as to realize different stiffness ranges. In the present application, the stiffness range of the driver is from a value greater than zero to infinity.

[0039] The driving principle: assuming that the position of the spring mounting frame 18 along the lead screw 29 is fixed, when the external load is zero, the spring mounting frame 18 will not be deflected, the spring 19 will not be deformed, and the driving motor 43 drives the sun gear 9 to rotate, thereby driving the output end (i.e. the planet carrier 7) to rotate; when the external load is not zero, the load force is transmitted to the inner tooth ring 14 and the sun gear 9 in a certain proportion, and the spring mounting frame 18 connected with the inner tooth ring 14 will be deflected under the action of force, so that the spring 19 is compressed, forming a buffering effect.

[0040] In the present application, the lead screw 29 is used as the mechanism for realizing variable stiffness. When there is no load, the variable stiffness motor 22 can realize stiffness change with very small force, and when driving, the variable stiffness motor 22 does not need to output force for maintaining stiffness.

[0041] The embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A variable stiffness hybrid elastic drive based on a variable stiffness planetary gear reducer unit, characterized in that: It comprises a protective housing (1), a variable stiffness planetary gear reducer unit (2) and an input motor end (3); The variable stiffness planetary gear reducer unit (2) comprises a planet carrier (7), a sun gear (9), a planet carrier bearing (10), a planet shaft (11), an inner gear ring (14), a spring mounting frame (18), a spring (19), a steel ball linear bearing (21), a variable stiffness motor (22), a variable stiffness motor end gear (26), a grooved connecting rod (27), a screw nut (28), a screw (29), a screw end gear (31) and a planet gear (33); the planet carrier bearing (10), the inner gear ring (14) and the spring mounting frame The mounting frame (18) is arranged in sequence, and the planetary frame (7) is coaxially mounted inside the planetary frame bearing (10). The upper end of the sun gear (9) is rotatably mounted in the middle of the planetary frame (7), and the lower end is inserted into the middle of the sun gear driving end (39) of the input motor end (3); one end of three planetary shafts (11) is also fixed on the planetary frame (7), and the other ends of the three planetary shafts (11) are respectively fixed inside a planetary wheel (33), and the outer wall of the planetary wheel (33) is matched with the inner wall of the inner gear ring (14); the inner gear ring (14) is connected to the spring The mounting frames (18) are matched with each other through slider rails; a plurality of rails are provided on the outside of the spring mounting frame (18), each rail is matched with a steel ball linear bearing (21), and a spring (19) is provided between the spring mounting frame (18) and the steel ball linear bearing (21); the variable stiffness motor (22) is mounted on the variable stiffness motor mounting frame (23), and the output end of the variable stiffness motor (22) passes through the middle hole of the variable stiffness motor end gear (26) and is fixed; one end of the lead screw (29) is matched with the lead screw nut (28) After closing, it passes through the variable stiffness motor mounting frame (23) and is fixedly connected to the screw end gear (31). The other end of the screw (29) is inserted into the inner hole of the flange bearing (34) of the input motor end (3); the screw nut (28) is connected to the screw nut connector (25), and the circular hole of the screw nut connector (25) cooperates with the circular hole side of the slotted connecting rod (27) and is penetrated by a plug bolt; the notch side of the slotted connecting rod (27) cooperates with the circular hole on the spring mounting frame (18) and is also penetrated by a plug bolt; The inner gear ring (14) is connected to the inner gear ring positioning frame (37) of the input motor end (3); The protruding steel balls of the steel ball linear bearing (21) are tangentially matched with the conical grooves (45) on the inner wall of the driver housing (6) of the protective housing (1).

2. The variable stiffness hybrid elastic actuator according to claim 1, characterized in that: The protective housing (1) is formed by connecting a driver cover plate (4) and a driver housing (6).

3. The variable stiffness hybrid elastic actuator according to claim 2, characterized in that: The input motor end (3) includes a drive motor (43), the drive motor (43) is connected to the drive motor outer sleeve (35), and a flange bearing (34) is embedded in the drive motor outer sleeve (35); the output end of the drive motor (43) is connected to the sun gear drive end (39), and a sun gear drive end bearing (36) is embedded on the outer side of the sun gear drive end (39), one end of the sun gear drive end bearing (36) is in contact with the flange of the sun gear drive end (39), and the other end is tightened by a screw.

4. The variable stiffness parallel-parallel elastic actuator according to claim 3, characterized in that: The drive housing (6) is connected to the motor outer sleeve (35), and the drive cover (4) presses the planetary carrier bearing (10).

5. The variable stiffness parallel-parallel elastic actuator according to claim 3, characterized in that: The variable stiffness motor mounting frame (23) is connected to the outer sleeve (35) of the driving motor.

6. The variable stiffness parallel-parallel elastic actuator according to claim 3, characterized in that: One end of the inner gear ring positioning frame (37) close to the outer sleeve (35) of the driving motor is pressed against the sun gear driving end bearing (36).

7. The variable stiffness parallel-parallel elastic actuator according to claim 1, characterized in that: The upper part of the sun gear (9) is mounted in the inner hole of the sun gear bearing (8), and the sun gear bearing (8) is embedded in the through hole in the middle of the planet carrier (7).

8. The variable stiffness parallel-parallel elastic actuator according to claim 1, characterized in that: A plurality of slide rails (15) are evenly installed on the outer side of the inner gear ring (14), and a plurality of sliders (17) are evenly installed on the inner side of the spring mounting frame (18), and the sliders (17) slide along the slide rails (15).

9. The variable stiffness parallel-parallel elastic actuator according to claim 1, characterized in that: A set of tracks is composed of two optical axes (20), and the steel ball linear bearing (21) moves axially along the optical axes (20).

10. The variable stiffness parallel-parallel elastic actuator according to claim 1, characterized in that: Both ends of the planetary shaft (11) are fixed by gaskets and retaining springs.

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