Humanoid robot and knee joint thereof with variable stiffness and variable reduction ratio functions

Abstract

The invention discloses a humanoid robot and knee joints with variable stiffness and variable reduction ratio functions thereof, and the humanoid robot comprises thighs, push rods, first connecting rods, second connecting rods, first guide rods, second guide rods, variable stiffness mechanisms and shanks, the upper ends of the thighs are rotatably connected with the upper ends of the push rods, and the lower parts of the thighs are rotatably connected with one ends of the two first connecting rods; the thigh lower end is rotationally connected with the shank upper end; the lower end of the push rod is coaxially and rotationally connected with the other ends of the two first connecting rods and one end of a second connecting rod in sequence from inside to outside; the other end of the second connecting rod is rotationally connected to shafts in the middles of the outer sides of the first guide rod and the second guide rod; the upper ends of the first guide rod and the second guide rod which are in mirror image are rotationally connected to the inner sides of shafts at the upper ends of the shanks respectively; the first guide rod and the second guide rod are respectively provided with a sliding groove, and the variable stiffness mechanism is provided with a fulcrum sliding in the sliding grooves. And the variable stiffness mechanism is also connected with a plate spring in the shank. The knee joint integrates high outbreak, buffering and energy storage, and long-time high-dynamic movement of the humanoid robot is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of humanoid robots, and in particular relates to a humanoid robot knee joint with variable stiffness and variable reduction ratio functions. Background Art

[0002] Humanoid robots can replace humans in performing various tasks without changing the environment by imitating human appearance and movement. In recent years, they have become a hot field in robotics research. In the movement of humanoid robots, the buffering capacity, high explosive force and energy storage characteristics of the knee joint are crucial for sustained high-dynamic movement. However, the current knee joints are difficult to meet the above requirements. Therefore, designing a new knee joint with the above functions is the key to improving the running and jumping capabilities of humanoid robots and other high-dynamic tasks.

[0003] The knee joint of a humanoid robot needs a larger speed output and torque output capacity during high-dynamic operation, which requires a higher-power drive motor. However, a high-power drive motor increases the mass and moment of inertia of the robot, which will reduce the robot's rapid response capability. In addition, due to the size limitation of the robot, a high-power motor cannot be installed on the robot's joint. Since the area where the robot needs to move quickly and the area where it needs to move with high torque are inconsistent, the robot's high-dynamic movement capability can be improved by changing the reduction ratio. However, the existing variable reduction ratio joints have one or more defects such as complex structure, low load-bearing torque, poor variable reduction ratio curve, and low reliability. After assembly, when the required high-dynamic task changes, it is difficult to simply modify some of the simple parts to change its reduction ratio so as to adapt to the new high-dynamic task.

[0004] During the high-dynamic motion of humanoid robots, joint flexibility can not only alleviate the impact force and protect the robot, but also reduce the power output of the joints and increase the robot's operating time. Variable stiffness joints can be applied to energy storage in different motion situations, which helps to increase the energy storage and buffering effect in different motion situations. Existing variable stiffness joints have the defects of small output torque and complex structure, which are difficult to meet the high-dynamic motion requirements of humanoid robots. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a humanoid robot knee joint with variable stiffness and variable reduction ratio functions.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A knee joint of a humanoid robot with variable stiffness and variable reduction ratio functions comprises a thigh, a push rod, a first connecting rod, a second connecting rod, a first guide rod, a second guide rod, a variable stiffness mechanism and a shank, wherein the first guide rod and the second guide rod are mirror images of each other;

[0008] The upper end of the thigh is rotatably connected to the upper end of the push rod, the lower part of the thigh is rotatably connected to one end of the two first connecting rods, and the lower end of the thigh is rotatably connected to the upper end of the calf;

[0009] The lower end of the push rod is coaxially connected to the other ends of the two first connecting rods and one end of the second connecting rod in sequence from the inside to the outside, and the other end of the second connecting rod is connected to the shaft in the middle of the outer sides of the first guide rod and the second guide rod;

[0010] The upper ends of the first guide rod and the second guide rod are respectively rotatably connected to the inner side of the shaft at the upper end of the calf; the first guide rod and the second guide rod are also respectively provided with a slide groove, and the variable stiffness mechanism is provided with a fulcrum sliding in the slide groove; the variable stiffness mechanism is also connected to the leaf spring of the calf.

[0011] In the above technical scheme, the thigh includes a thigh structure, a first thigh shaft, a second thigh shaft, a driver A and a joint bearing; the first thigh shaft and the second thigh shaft are respectively fixed in the holes at the upper end and the lower part of the thigh structure, and are used to connect the upper end of the push rod and one end of the first connecting rod; the driver A is fixed on the thigh structure; the joint bearings are respectively fixed in the cylindrical holes at the lower end of the thigh structure, and are used to connect the calf; the thigh also includes a joint encoder, and the joint encoder includes a magnetic ring and a reader, the reader is fixed in the cylindrical hole at the lower end of the thigh structure, and the magnetic ring is fixed on the calf.

[0012] In the above technical solution, the push rod includes a push rod first housing, a driver B, a push rod motor, a push rod second housing, a push rod encoder, a push rod ball screw, a push rod ball screw nut, a push rod third housing and a push rod output connector;

[0013] The first push rod housing is rotatably connected to the first thigh shaft via the first push rod bearing;

[0014] The driver B is mounted on the first housing of the push rod;

[0015] The push rod third housing is fixed to the lower end of the push rod second housing, and the push rod second housing is connected to the push rod first housing through the push rod second bearing;

[0016] The push rod motor includes a stator and a rotor, wherein the stator is located inside the first housing of the push rod, the rotor is located inside the stator, and the rotor is fixed on the second housing of the push rod;

[0017] A push rod ball screw nut is fixed inside the push rod third housing, the push rod ball screw nut is sleeved on the push rod ball screw, and a push rod output connector is fixed at the end of the push rod ball screw;

[0018] The push rod encoder comprises a magnetic ring and a reader, wherein the magnetic ring is fixed on the second shell of the push rod, and the reader is fixed on the first shell of the push rod.

[0019] In the above technical solution, the first connecting rod is in a straight line shape and consists of a first connecting rod structure and a first connecting rod bearing; circular holes are provided at both ends of the first connecting rod structure, and the first connecting rod bearing is fixed inside the circular holes, which are respectively connected to the second rotating shaft of the thigh and the second connecting rod.

[0020] In the above technical solution, the second connecting rod is H-shaped and consists of a second connecting rod input shaft, a second connecting rod structural member and a second connecting rod bearing; circular holes are provided at both ends of the second connecting rod structural member, and the second connecting rod bearing is fixed inside the circular holes; the second connecting rod bearing near one end of the push rod output connecting member is provided with a second connecting rod input shaft, and the second connecting rod input shaft is sequentially sleeved with the push rod output connecting member, the first connecting rod structural member and the second connecting rod structural member from the inside to the outside.

[0021] In the above technical solution, the first guide rod and the second guide rod are both composed of a guide rod structure, a guide rod bearing and a guide rod input shaft. The guide rod structure is provided with a first circular hole, a second circular hole and a slide groove, the first circular hole is located at the upper end of the guide rod structure, the second circular hole is located in the middle of one side of the guide rod structure, and the slide groove is located in the lower middle part of the guide rod structure; the guide rod bearing is fixed in the first circular hole, the guide rod input shaft is fixed in the second circular hole, the guide rod bearing is fixed on the calf, and the guide rod input shaft is fixed inside the second connecting rod bearing away from the push rod output connecting member.

[0022] In the above technical solution, the variable stiffness mechanism includes a first bracket of the stiffness adjustment mechanism, a second bracket of the stiffness adjustment mechanism, a ball screw of the stiffness adjustment mechanism, a guide rail of the stiffness adjustment mechanism, a nut of the ball screw of the stiffness adjustment mechanism, a copper sleeve of the guide rail of the stiffness adjustment mechanism, a slider of the stiffness adjustment mechanism, a second bearing of the stiffness adjustment mechanism, a motor of the stiffness adjustment mechanism, an output shaft of the motor of the stiffness adjustment mechanism, an encoder shaft of the motor of the stiffness adjustment mechanism, and an encoder of the motor of the stiffness adjustment mechanism;

[0023] The first bracket of the rigidity adjustment mechanism and the second bracket of the rigidity adjustment mechanism are fixed to each other to form a support frame of the rigidity variable mechanism;

[0024] The two ends of the steel adjustment mechanism ball screw are respectively connected to the inside of the first bracket of the steel adjustment mechanism through the first bearing of the steel adjustment mechanism, and the steel adjustment mechanism ball screw nut is sleeved on the steel adjustment mechanism ball screw; one end of the steel adjustment mechanism ball screw close to the second bracket of the steel adjustment mechanism is also connected to the output shaft of the steel adjustment mechanism motor;

[0025] A guide rail of the rigidity adjustment mechanism parallel to the ball screw of the rigidity adjustment mechanism is also fixed inside the first bracket of the rigidity adjustment mechanism, and a copper sleeve of the guide rail of the rigidity adjustment mechanism is sleeved on the guide rail of the rigidity adjustment mechanism;

[0026] The ball screw of the rigidity adjustment mechanism and the guide rail of the rigidity adjustment mechanism are both located inside the slider of the rigidity adjustment mechanism; pivot points are arranged on both sides of the slider of the rigidity adjustment mechanism, and the second bearing of the rigidity adjustment mechanism is sleeved on the pivot points, and the second bearing of the rigidity adjustment mechanism slides in the slide groove of the guide rod;

[0027] The rigidity adjustment mechanism motor comprises a stator and a rotor, the rotor is located inside the stator, the stator is located at the upper end of the second bracket of the rigidity adjustment mechanism, the rigidity adjustment mechanism motor output shaft is fixed inside the rotor, and the rigidity adjustment mechanism motor encoder shaft is fixed at the lower end of the rigidity adjustment mechanism motor output shaft;

[0028] The motor encoder of the rigidity adjustment mechanism comprises a magnetic ring and a reader, wherein the magnetic ring is fixed on the motor encoder shaft of the rigidity adjustment mechanism, and the reader is fixed on the motor gland of the rigidity adjustment mechanism.

[0029] In the above technical solution, the calf includes a calf structure, a first joint shaft, a second joint shaft, a leaf spring and a driver C, and the calf structure is U-shaped; the first joint shaft and the second joint shaft are respectively fixed in the holes at the upper end of the calf structure, the outer sides of the first joint shaft and the second joint shaft are respectively connected to the joint bearings, and the inner sides of the first joint shaft and the second joint shaft are respectively connected to the first guide rod and the second guide rod; the leaf spring is fixed in the hole in the middle part of the calf structure, and the leaf spring is connected to the shafts with keyways on both sides of the second bracket of the rigidity adjustment mechanism; the driver C is fixed on the calf structure.

[0030] In the above technical solution, the first guide rod, the second guide rod, the variable stiffness mechanism and the calf constitute a variable stiffness module of the knee joint, and the thigh, the push rod, the first connecting rod, the second connecting rod, the first guide rod and the second guide rod constitute a variable reduction ratio module of the knee joint.

[0031] A humanoid robot comprises the above-mentioned knee joint with the functions of variable stiffness and variable reduction ratio.

[0032] The beneficial effects of the present invention are:

[0033] (1) The present invention provides a humanoid robot knee joint with both variable speed ratio and variable stiffness, wherein the variable speed ratio is related to the joint angle and is a passive variable speed ratio, and the variable stiffness is an active variable stiffness, and its stiffness range is 0 to infinity.

[0034] (2) The joint of the present invention has a symmetrical structure. From the output part of the push rod to the calf, the motion-force is transmitted bilaterally, which is more reliable than unilateral transmission. At the same time, bilateral transmission can also enable the joint to have a larger bearing torque.

[0035] (3) The present invention uses a push rod drive method to separate the joint driving part and the stiffness adjustment part, thereby reducing its axial length and making it easier to install it in the knee joint of a humanoid robot.

[0036] (4) The variable stiffness module of the joint in the present invention is connected in series to the rear of the variable reduction ratio module. The two are separated from each other and can be designed and optimized separately.

[0037] (5) In the present invention, there are many parameters related to the joint reduction ratio, and a better reduction ratio curve suitable for different high dynamic movements can be obtained through optimization.

[0038] (6) The present invention adopts a modular joint design. When different motion requirements of the robot require different reduction ratios, connecting rods of different lengths can be quickly replaced while keeping the upper and lower legs and driving joints unchanged, thereby changing the joint reduction ratio curve.

[0039] (7) The joint stiffness of the present invention is actively adjustable, and different stiffnesses can be suitable for the buffering and energy storage needs of different high-dynamic movements.

[0040] (8) When the fulcrum position in the variable stiffness mechanism of the present invention remains unchanged (other positions of zero stiffness and infinite stiffness), the stiffness of the joint increases with the increase of the load moment, which is more in line with the movement law of human skeletal muscles.

[0041] (9) The variable stiffness mechanism of the present invention has a rolling bearing sleeve on the outer side of the fulcrum, which reduces its friction and increases the service life of the joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the structure of the humanoid robot knee joint with variable stiffness and variable reduction ratio functions according to the present invention;

[0043] Figure 2 This is a schematic diagram of the thigh structure of the present invention;

[0044] Figure 3 It is a cross-sectional view of the third rotation axis of the thigh according to the present invention;

[0045] Figure 4 is a cross-sectional view of the push rod of the present invention;

[0046] Figure 5 This is a structural diagram of the first housing of the push rod of the present invention;

[0047] Figure 6 This is the structural diagram of the first connecting rod of the present invention;

[0048] Figure 7 This is a structural diagram of the second connecting rod of the present invention;

[0049] Figure 8 Structural diagram of the first guide rod and the second guide rod of the present invention;

[0050] Fig. 9 This is a structural diagram of the variable stiffness mechanism of the present invention;

[0051] Fig.10 This is a structural diagram of the first bracket and the second bracket of the rigidity adjustment mechanism of the present invention;

[0052] Fig.11 It is a cross-sectional view of the variable stiffness mechanism of the present invention;

[0053] Fig.12 This is a structural diagram of the lower leg according to the present invention;

[0054] Fig.13 This is the variable stiffness principle diagram of the present invention;

[0055] Fig.14 This is a schematic diagram of the joint speed reduction ratio of the present invention;

[0056] In the figure: 100-thigh, 200-push rod, 300-first connecting rod, 400-second connecting rod, 500-guide rod, 500a-first guide rod, 500b-second guide rod, 600-variable stiffness mechanism, 700-calf, 11-first rotating shaft axis, 12-second rotating shaft axis, 13-third rotating shaft axis, 14-fourth rotating shaft axis, 15-fifth rotating shaft axis, 16-sixth rotating shaft axis, 101-thigh structure, 102-thigh first rotating shaft, 103-thigh second rotating shaft, 104-driver A, 105-joint bearing, 106-joint bearing first pressure cover, 107-joint bearing second pressure cover, 108-joint encoder, 1081-joint encoder magnetic ring, 1082-joint Encoder reader, 201-push rod first housing, 202-push rod first bearing, 203-driver mounting plate, 204-driver B, 205-push rod dust cover, 206-push rod heat sink, 207-push rod motor, 208-push rod second housing, 209-push rod encoder, 210-push rod first pressure ring, 211-push rod second bearing, 212-push rod second pressure ring, 213-push rod ball screw, 214-push rod ball screw nut, 215-push rod third housing, 216-push rod third pressure ring, 217-push rod output connector, 2071-push rod motor stator, 2072-push rod motor rotor, 2091-push rod encoder magnetic ring, 2092-push rod encoder reader, 301-first A connecting rod structure, 302-a first connecting rod bearing, 401-a second connecting rod input shaft, 402-a second connecting rod structure, 403-a second connecting rod bearing, 501-a first guide rod structure, 502-a first guide rod bearing, 503-a first guide rod bearing baffle, 504-a first guide rod input shaft, 505-a second guide rod structure, 506-a second guide rod bearing, 507-a second guide rod bearing baffle, 508-a second guide rod input shaft, 601-a first bracket of a rigid adjustment mechanism, 602-a second bracket of a rigid adjustment mechanism, 603-a fixed plate of a rigid adjustment mechanism, 604-a first bearing of a rigid adjustment mechanism, 605-a ball screw of a rigid adjustment mechanism, 606-a guide rail of a rigid adjustment mechanism, 607-a ball screw nut of a rigid adjustment mechanism, 608-a rigid adjustment mechanism Mechanism locking nut, 609-adjustment mechanism guide rail copper sleeve, 610-adjustment mechanism slider, 611-adjustment mechanism second bearing, 612-adjustment mechanism second bearing baffle, 613-adjustment mechanism motor, 614-adjustment mechanism motor output shaft, 615-adjustment mechanism motor encoder shaft, 616-adjustment mechanism motor pressure cover, 617-adjustment mechanism motor encoder, 6131-adjustment mechanism motor stator, 6132-adjustment mechanism motor rotor, 6171-adjustment mechanism motor encoder magnetic ring, 6172-adjustment mechanism motor encoder reader, 701-calf structure, 702-first joint shaft, 703-second joint shaft, 704-leaf spring, 705-driver C, 706-calf bearing baffle. DETAILED DESCRIPTION

[0057] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0058] like Figure 1 As shown, a humanoid robot knee joint with variable stiffness and variable reduction ratio functions of the present invention is composed of a thigh 100, a push rod 200, two first connecting rods 300, a second connecting rod 400, a first guide rod 500a, a second guide rod 500b, a variable stiffness mechanism 600, and a calf 700, wherein the first guide rod 500a and the second guide rod 500b are mirror images of each other. One end of the push rod 200 is rotatably connected to the upper end of the thigh 100, one end of the first connecting rod 300 is rotatably connected to the lower part of the thigh 100, the outer side of the other end of the push rod 200 is connected to the other end of the first connecting rod 300, the hole at one end of the second connecting rod 400 is connected to the hole at the other end of the first connecting rod 300, and the second connecting rod 400 is located on the outer side of the first connecting rod 300, and the center lines of the other end of the push rod 200, the other end of the first connecting rod 300, and one end of the second connecting rod 400 coincide with each other and are defined as the fourth shaft axis 14. The holes at the other end of the second connecting rod 400 are respectively connected to the shafts at the middle of the outer side of the first guide rod 500a and the second guide rod 500b, and the center lines of the other end of the second connecting rod 400, the shaft at the middle of the outer side of the first guide rod 500a, and the shaft at the middle of the outer side of the second guide rod 500b coincide and are defined as the fifth rotating shaft axis 15. The holes at the upper ends of the first guide rod 500a and the second guide rod 500b are respectively fixed to the shaft at the upper end of the shank 700 (the shaft axis is the third rotating shaft axis 13). The first guide rod 500a and the second guide rod 500b are respectively provided with a slide groove, and the variable stiffness mechanism 600 is provided with a fulcrum and can slide in the slide groove. The shafts with keyways on both sides of the variable stiffness mechanism 600 are fixed on the shank 700, and the axis of the cylinder is defined as the sixth rotating shaft axis 16.

[0059] like Figure 2 and Figure 3As shown, the thigh 100 is composed of a thigh structure 101, a thigh first rotating shaft 102, a thigh second rotating shaft 103, a driver A104, two joint bearings 105, a joint bearing first pressure cover 106, a joint bearing second pressure cover 107 and a joint encoder 108. Among them, the center lines of the thigh first rotating shaft 102 and the thigh second rotating shaft 103 are respectively recorded as the first rotating shaft axis 11 and the second rotating shaft axis 12, and the center lines of the two cylinders at the lower end of the thigh structure 101 are recorded as the third rotating shaft axis 13. The first thigh shaft 102 and the second thigh shaft 103 are respectively fixed in the holes at the upper end and the lower part of the thigh structure 101. One end of the push rod 200 is rotatably connected to the first thigh shaft 102 and the push rod 200 can rotate around the first shaft axis 11. One end of the first connecting rod 300 is connected to the second thigh shaft 103 and the first connecting rod 300 can rotate around the second shaft axis 12. The calf 700 is connected to the lower end of the thigh structure 101 and the calf 700 can rotate around the third shaft axis 13. The driver A104 is fixed to the back plate of the thigh structure 101. Two joint bearings 105 are respectively fixed in the cylindrical holes at the lower end of the thigh structure 101 and are respectively fixed by the first joint bearing pressure cover 106 and the second joint bearing pressure cover 107. The first joint bearing pressure cover 106 and the second joint bearing pressure cover 107 are respectively fixed to the side wall of the thigh structure 101. The joint encoder 108 is composed of a joint encoder magnetic ring 1081 and a joint encoder reader 1082 . The joint encoder reader 1082 is fixed to the outside of the first joint bearing pressure cover 106 , and the joint encoder magnetic ring 1081 is fixed to the first calf joint shaft 702 .

[0060] like Figure 4As shown, the push rod 200 is composed of a push rod first housing 201, a push rod first bearing 202, a driver mounting plate 203, a driver B204, a push rod dust cover 205, a push rod heat sink 206, a push rod motor 207, a push rod second housing 208, a push rod encoder 209, a push rod first pressing ring 210, a push rod second bearing 211, a push rod second pressing ring 212, a push rod ball screw 213, a push rod ball screw nut 214, a push rod third housing 215, a push rod third pressing ring 216, and a push rod output connector 217. The push rod first bearing 202 is fixed to the circular hole of the push rod first housing 201 and is rotatably connected to the thigh first rotating shaft 102. The driver mounting plate 203 is fixed to the push rod first housing 201, and the driver B204 is fixed to the driver mounting plate 203. The push rod heat sink 206 is circumferentially fixed to the push rod first housing 201, which helps the push rod motor 207 to dissipate heat. The push rod third housing 215 is fixed to the lower end of the push rod second housing 208. The push rod second housing 208 is connected to the push rod first housing 201 through the push rod second bearing 211. The push rod third housing 215 and the push rod second housing 208 can rotate around the push rod first housing 201 and the three are coaxial. The push rod motor 207 is composed of a push rod motor stator 2071 and a push rod motor rotor 2072. The push rod motor stator 2071 is located inside the push rod first housing 201, and the push rod motor rotor 2072 is located inside the push rod motor stator 2071 and fixed to the push rod second housing 208. The ball screw nut 214 is fixed inside the push rod third housing 215, and the push rod ball screw 213 is located inside the push rod ball screw nut 214. When the push rod motor stator 2071 drives the push rod motor rotor 2072 to rotate, the push rod ball screw nut 214 can be driven to rotate through the push rod second housing 208 and the push rod third housing 215, thereby driving the push rod ball screw 213 to move along its axis. The push rod encoder 209 is composed of a push rod encoder magnetic ring 2091 and a push rod encoder reader 2092. The push rod encoder magnetic ring 2091 is fixed on the push rod second housing 208, and the push rod encoder reader 2092 is fixed on the push rod first housing 201. The angle read by the push rod encoder reader 2092 is the relative rotation angle of the push rod encoder magnetic ring 2091 and the push rod encoder reader 2092, that is, the angle at which the push rod motor rotor 2072 and the push rod ball screw nut 214 rotate around their axes. The first push rod pressure ring 210 is fixed to the side of the first push rod housing 201 to press the push rod motor stator 2071. The second push rod pressure ring 212 is fixed to the side of the third push rod housing 215 to press the second push rod bearing 211. The third push rod pressure ring 216 is fixed to the third push rod housing 215 to press the push rod ball screw nut 214 to prevent it from falling off. The push rod output connector 217 is fixed to the end of the push rod ball screw 213 as the output part of the push rod 200. The upper end of the first push rod housing 201 is a hollow U-shaped structure ( Figure 5), the push rod dust cover 205 is installed inside the U-shaped structure, located at the upper end of the push rod ball screw 213, with a gap between the two, and the push rod dust cover 205 is coaxial with the push rod ball screw 213.

[0061] like Figure 6 As shown, the first connecting rod 300 is in a straight line shape, and is composed of a first connecting rod structure 301 and a first connecting rod bearing 302. Round holes are provided at both ends of the first connecting rod structure 301, and the first connecting rod bearing 302 is fixed inside the round holes.

[0062] like Figure 7 As shown, the second connecting rod 400 is H-shaped, and consists of a second connecting rod input shaft 401, a second connecting rod structural member 402 and a second connecting rod bearing 403. The axes of the holes on both sides of the second connecting rod structural member 402 coincide with the fourth rotating shaft axis 14 and the fifth rotating shaft axis 15 respectively. The second connecting rod bearing 403 is located in the holes on both sides of the second connecting rod structural member 402. The second connecting rod input shaft 401 is located in the hole on one side of the second connecting rod structural member 402 and coincides with the fourth rotating shaft axis 14.

[0063] like Figure 8 As shown, the first guide rod 500a is composed of a first guide rod structure 501, a first guide rod bearing 502, a first guide rod bearing baffle 503 and a first guide rod input shaft 504. The first guide rod structure 501 is provided with a first circular hole (the hole at the upper end), a second circular hole (the hole in the middle) and a slide groove. The first guide rod bearing 502 is fixed in the first circular hole of the first guide rod structure 501, the first guide rod input shaft 504 is fixed in the second circular hole of the first guide rod structure 501, and the first guide rod bearing baffle 503 is fixed outside the first circular hole of the first guide rod structure 501. The axis of the first circular hole of the first guide rod structure 501 coincides with the axis of the third rotating shaft 13, and the axis of the second circular hole of the first guide rod structure 501 coincides with the axis of the fifth rotating shaft 15. The structure of the second guide rod 500b is composed of a second guide rod structural member 505, a second guide rod bearing 506, a second guide rod bearing baffle 507 and a second guide rod input shaft 508. The specific structure is the same as that of the first guide rod 500a and will not be repeated here.

[0064] like Fig. 9 , 10As shown in FIG. 11 , the variable stiffness mechanism 600 is composed of a first support 601 of the rigidity adjustment mechanism, a second support 602 of the rigidity adjustment mechanism, a fixed plate 603 of the rigidity adjustment mechanism, two first bearings 604 of the rigidity adjustment mechanism, a ball screw 605 of the rigidity adjustment mechanism, a guide rail 606 of the rigidity adjustment mechanism, a ball screw nut 607 of the rigidity adjustment mechanism, a locking nut 608 of the rigidity adjustment mechanism, a copper sleeve 609 of the guide rail of the rigidity adjustment mechanism, a slider 610 of the rigidity adjustment mechanism, a second bearing 611 of the rigidity adjustment mechanism, a second bearing baffle 612 of the rigidity adjustment mechanism, a motor 613 of the rigidity adjustment mechanism, an output shaft 614 of the rigidity adjustment mechanism motor, an encoder shaft 615 of the rigidity adjustment mechanism motor, a gland 616 of the rigidity adjustment mechanism motor, and an encoder 617 of the rigidity adjustment mechanism motor. The first support 601 of the rigidity adjustment mechanism and the second support 602 of the rigidity adjustment mechanism are fixed to each other to form a support frame for other components in the variable stiffness mechanism 600. Axes with keyways are provided on both sides of the second support 602 of the rigidity adjustment mechanism for connecting with the leaf spring 704. The two first bearings 604 of the rigid adjustment mechanism are located in the internal holes of the first bracket 601 of the rigid adjustment mechanism, and the first bearings 604 of the rigid adjustment mechanism are prevented from falling off by the rigid adjustment mechanism fixing plate 603 fixed on the first bracket 601 of the rigid adjustment mechanism; the guide rail 606 of the rigid adjustment mechanism is fixed inside the first bracket 601 of the rigid adjustment mechanism, and the two ends of the ball screw 605 of the rigid adjustment mechanism are fixed inside the two first bearings 604 of the rigid adjustment mechanism, and the ball screw 605 of the rigid adjustment mechanism can rotate around its axis. The ball screw nut 607 of the rigid adjustment mechanism and the copper sleeve 609 of the guide rail of the rigid adjustment mechanism are both fixed inside the slider 610 of the rigid adjustment mechanism, and the ball screw nut 607 of the rigid adjustment mechanism is sleeved on the ball screw 605 of the rigid adjustment mechanism, and the locking nut 608 of the rigid adjustment mechanism is located at one end of the slider 610 of the rigid adjustment mechanism, and is used to fix the ball screw nut 607 of the rigid adjustment mechanism, and the copper sleeve 609 of the guide rail of the rigid adjustment mechanism is sleeved on the guide rail 606 of the rigid adjustment mechanism. The rigidity adjustment mechanism slider 610 moves on the axis of the rigidity adjustment mechanism ball screw 605 (i.e., the axis of the rigidity adjustment mechanism guide rail 606). A fulcrum is provided on both sides of the rigidity adjustment mechanism slider 610, and the rigidity adjustment mechanism second bearing 611 is sleeved on the fulcrum and can rotate around the fulcrum. The rigidity adjustment mechanism second bearing stopper 612 is fixed on the outside of the fulcrum to prevent the rigidity adjustment mechanism second bearing 611 from falling off.The rigidity adjustment mechanism motor 613 is composed of a rigidity adjustment mechanism motor stator 6131 and a rigidity adjustment mechanism motor rotor 6132, and the rigidity adjustment mechanism motor rotor 6132 is located inside the rigidity adjustment mechanism motor stator 6131, and the rigidity adjustment mechanism motor stator 6131 is located in a shell composed of the upper end of the rigidity adjustment mechanism second bracket 602 and the rigidity adjustment mechanism motor pressure cover 616, the rigidity adjustment mechanism motor output shaft 614 is fixed on the inner side of the rigidity adjustment mechanism motor rotor 6132, and the rigidity adjustment mechanism motor encoder shaft 615 is fixed on the lower end of the rigidity adjustment mechanism motor output shaft 614; the rigidity adjustment mechanism motor encoder 617 is composed of a rigidity adjustment mechanism motor encoder magnetic ring 6171 and a rigidity adjustment mechanism motor encoder reader 6172, the rigidity adjustment mechanism motor encoder magnetic ring 6171 is fixed on the rigidity adjustment mechanism motor encoder shaft 615, and the rigidity adjustment mechanism motor encoder reader 6172 is fixed on the rigidity adjustment mechanism motor pressure cover 616. One end of the rigidity adjustment mechanism ball screw 605 close to the rigidity adjustment mechanism second bracket 602 is also connected to the rigidity adjustment mechanism motor output shaft 614 .

[0065] like Fig.12 As shown, the calf 700 is composed of a calf structure 701, a first joint shaft 702, a second joint shaft 703, two leaf springs 704, a driver C705 and a calf bearing baffle 706. The calf structure 701 is U-shaped. The first joint shaft 702 and the second joint shaft 703 are respectively fixed in the holes on the upper side of the calf structure 701, specifically: the first joint shaft 702 is fixed in the hole on the left side of the calf structure 701, and the second joint shaft 703 is fixed in the hole on the right side of the calf structure 701. The first joint shaft 702 and the second joint shaft 703 are respectively connected to the joint bearing 105 on the outside, and are respectively connected to the first guide rod bearing 502 and the second guide rod bearing 506 on the inside; the two leaf springs 704 are fixed in the hole in the middle of the calf structure 701. The axis of the upper hole of the calf structure 701 coincides with the axis of the third rotating shaft 13, and the axis of the middle hole coincides with the axis of the sixth rotating shaft 16. Two lower leg bearing baffles 706 are respectively fixed on the inner side of the first joint shaft 702 and the second joint shaft 703. The driver C705 is fixed on the lower leg structure 701.

[0066] The variable stiffness principle of the humanoid robot knee joint with variable stiffness and variable reduction ratio function of the present invention is as follows: Fig.13, the guide rods 500 (the first guide rod 500a and the second guide rod 500b), the variable stiffness mechanism 600, and the calf 700 constitute the variable stiffness module of the joint. The guide rods 500 (the first guide rod 500a and the second guide rod 500b) rotate around the third rotating shaft axis 13, the fulcrum of the variable stiffness mechanism 600 (i.e. the fulcrums on both sides of the rigidity adjustment mechanism slider 610) are located in the slide grooves of the first guide rod 500a and the second guide rod 500b and can move in the slide grooves, the variable stiffness mechanism 600 is fixed on the leaf spring 704 of the calf 700, the first guide rod 500a and the second guide rod 500b are the input parts, and the calf 700 is the output part. When the joint does not bear external torque (i.e. when the calf 700 has no torque output), the first guide rod 500a, the second guide rod 500b, the variable stiffness mechanism 600, and the calf 700 are collinear, i.e. θ 1 The angle value is 0. When there is an external torque, due to the flexibility of the leaf spring 704, the first guide rod 500a, the second guide rod 500b and the calf 700 form an angle θ 1 , which is related to the external torque and is defined as the joint deformation angle. At the same time, under the action of the external torque, the deformation angle of the leaf spring 704 is θ 2 The length of the variable stiffness mechanism 600 (the distance from the fulcrum axis to the leaf spring axis) can be adjusted according to the stiffness adjustment mechanism ball screw 605, specifically: the control computer sends a control instruction through the driver C705 to drive the stiffness adjustment mechanism motor rotor 6132 in the stiffness adjustment mechanism motor 613 to rotate, thereby driving the stiffness adjustment mechanism ball screw 605 to rotate through the stiffness adjustment mechanism motor output shaft 614. Due to the existence of the stiffness adjustment mechanism guide rail 606, the rotation of the stiffness adjustment mechanism ball screw 605 will cause the stiffness adjustment mechanism slider 610 to move linearly along the stiffness adjustment mechanism guide rail 606 (stiffness adjustment mechanism ball screw 605), and the fulcrum on the stiffness adjustment mechanism slider 610 moves linearly along the stiffness adjustment mechanism guide rail 606 (stiffness adjustment mechanism ball screw 605). Define the length ratio of the variable stiffness mechanism 600 and the lower leg 700 as r. The load moment and stiffness of the joint decrease as r increases. When r is 0, the stiffness of the joint is infinite. When r is 1, the stiffness of the joint is 0. The stiffness of the joint also increases with the joint deformation angle θ. 1 This is consistent with the changing characteristics of human skeletal muscle stiffness.

[0067] The joint load moment T and joint deformation angle θ are 1 The relationship and its differential relationship (i.e., joint stiffness K and θ 1 The calculation formula of the relationship is as follows:

[0068] θ 1 With θ 2 The relationship is:

[0069] Joint load moment T versus joint deformation angle θ1 The work done is equal to the energy stored in the leaf spring 704, that is: Wherein, k is twice the stiffness of the leaf spring 704;

[0070] According to the above formula, the joint load moment T and joint deformation angle θ can be calculated: 1 The relationship between them is:

[0071]

[0072] Convert the above formula to θ 1 By taking the differential, we can get the joint stiffness K and the joint deformation angle θ 1 The relationship between them is:

[0073]

[0074] From the above formula, it can be seen that the joint load moment T and joint stiffness K are both related to r and θ 1 When θ 1 When the value of θ remains unchanged, T and K decrease as the value of r decreases. When the value of r remains unchanged, T and K increase as θ decreases. 1 The value of r increases, which is consistent with the change characteristics of biological skeletal muscle stiffness. When the value of r is 0, the stiffness of the joint is infinite, and when the value of r is 1, the stiffness of the joint is 0.

[0075] The invention provides a humanoid robot knee joint with variable stiffness and variable reduction ratio function, and the reduction ratio principle is as follows: Fig.14As shown, the thigh 100, the push rod 200, the two first connecting rods 300, the second connecting rod 400, and the first guide rod 500a and the second guide rod 500b constitute a variable speed ratio module. When the length of the push rod 200 changes, the push rod 200 will push the first connecting rod 300 to rotate around the second rotating shaft axis 12, and the first connecting rod 300, the second connecting rod 400, the guide rod 500 (the first guide rod 500a and the second guide rod 500b), the second rotating shaft axis 12 and the third rotating shaft axis 13 form a four-bar linkage, so the rotation of the first connecting rod 300 around the second rotating shaft axis 12 will drive the guide rod 500 (the first guide rod 500a and the second guide rod 500b) to move around the third rotating shaft axis 13. The length change principle of the push rod 200 is: the control computer sends a control instruction through the driver B204 to drive the push rod motor rotor 6132 in the push rod motor 207 to rotate, thereby driving the push rod second housing 208 and the push rod third housing 216 to rotate, and then driving the push rod ball screw nut 214 to rotate, thereby driving the push rod ball screw 213 to move along its axial direction, so that the length of the push rod 200 changes. The ratio of the rotation angle of the push rod motor rotor 2172 in the push rod motor 207 to the rotation angle of the guide rod 500 is not constant, so the knee joint is a variable reduction ratio joint. Before the calculation formula of the reduction ratio and the joint angle, the following definition is made: the distance between the first shaft axis 11 and the second shaft axis 12 is L 0 , the distance between the second rotating shaft axis 12 and the third rotating shaft axis 13 is L 1 , the distance between the third rotating shaft axis 13 and the fourth rotating shaft axis 14 is L 2 , the distance L between the fourth rotating shaft axis 14 and the fifth rotating shaft axis 15 3 , the distance between the third rotating shaft axis 13 and the fifth rotating shaft axis 15 is L 4 , β 1 is the angle between the line connecting the second rotating shaft axis 12 and the fourth rotating shaft axis 14 and the line connecting the second rotating shaft axis 12 and the third rotating shaft axis 13, that is, the angle between the first connecting rod 300 and the thigh 100, β 2 is the angle between the extended line of the second shaft axis 12 and the third shaft axis 13 and the line of the third shaft axis 13 and the fifth shaft axis 15, that is, the angle between the guide rod 500 and the thigh 100, and h is the pitch of the push rod ball screw 213. The reduction ratio calculation formula of the joint is as follows:

[0076] Push rod 200 speed The rotation angle of the push rod motor 207 The relationship is:

[0077] The rotation speed of the first connecting rod 300 With push rod 200 speed The ratio is:

[0078]

[0079] Rotation angle of guide rod 500 The rotation speed of the first connecting rod 300 The ratio is:

[0080]

[0081] The reduction ratio of the joint is: R = R 1 ×R 2 ×R 3 .

[0082] Change L 0 , L 1 , L 2 , L 3 and L 4 The length of the joint can change the reduction ratio of the joint and the movement angle of the guide rod 500 β 2 The law of change of the joint is realized, that is, the variable reduction ratio of the joint is realized.

[0083] The invention discloses a humanoid robot knee joint variable stiffness module with variable stiffness and variable reduction ratio functions, which is connected in series to the rear end of the variable reduction ratio module. The knee joint movement angle α is β 2 With θ 1 Therefore, in the robot design process, the joint deformation angle θ can be calculated based on the joint torque required for robot movement. 1 , and then according to the joint motion angle α, joint deformation angle θ 1 The motion angle β of the variable stiffness mechanism is calculated 2 The relationship between the joint torque and the load required can be used to optimize the reduction ratio of the joint and obtain a reduction ratio law that is more suitable for the high dynamic motion of the robot. 0 , L 1 , L 2 , L 3 and L 4 The length of the gear ratio is 1 / 4, so the design can optimize a better reduction ratio variation rule. In the motion control of the robot, the joint angle α can be measured by the joint encoder 108, and the angle value can be sent to the control computer through the driver A104, so as to realize the joint angle reading during the robot motion process.

[0084] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A knee joint of a humanoid robot with variable stiffness and variable reduction ratio functions, characterized in that: The device comprises a thigh (100), a push rod (200), a first connecting rod (300), a second connecting rod (400), a first guide rod (500a), a second guide rod (500b), a variable stiffness mechanism (600) and a calf (700), wherein the first guide rod (500a) and the second guide rod (500b) are mirror images of each other; The upper end of the thigh (100) is rotatably connected to the upper end of the push rod (200), the lower part of the thigh (100) is rotatably connected to one end of two first connecting rods (300), and the lower end of the thigh (100) is rotatably connected to the upper end of the calf (700); The lower end of the push rod (200) is coaxially rotatably connected to the other ends of the two first connecting rods (300) and one end of the second connecting rod (400) in sequence from the inside to the outside, and the other end of the second connecting rod (400) is rotatably connected to the shaft in the middle of the outer sides of the first guide rod (500a) and the second guide rod (500b); The upper ends of the first guide rod (500a) and the second guide rod (500b) are respectively rotatably connected to the inner side of the shaft at the upper end of the calf (700); the first guide rod (500a) and the second guide rod (500b) are also respectively provided with a slide groove, and the variable stiffness mechanism (600) is provided with a fulcrum sliding in the slide groove; the variable stiffness mechanism (600) is also connected to the leaf spring (704) of the calf (700).

2. The knee joint of the humanoid robot with variable stiffness and variable reduction ratio function according to claim 1, characterized in that: The thigh (100) comprises a thigh structure (101), a first thigh rotating shaft (102), a second thigh rotating shaft (103), a driver A (104) and a joint bearing (105); the first thigh rotating shaft (102) and the second thigh rotating shaft (103) are respectively fixed in holes at the upper end and the lower part of the thigh structure (101), and are used to connect the upper end of the push rod (200) and one end of the first connecting rod (300); the driver A (104) is fixed on the thigh structure (101); the joint bearings (105) are respectively fixed in the cylindrical holes at the lower end of the thigh structure (101), and are used to connect the calf (700); the thigh (100) further comprises a joint encoder (108), and the joint encoder (108) comprises a magnetic ring and a reader, the reader is fixed in the cylindrical hole at the lower end of the thigh structure (101), and the magnetic ring is fixed on the calf (700).

3. The knee joint with variable stiffness and variable reduction ratio function of the humanoid robot according to claim 2, characterized in that: The push rod (200) comprises a push rod first housing (201), a driver B (204), a push rod motor (207), a push rod second housing (208), a push rod encoder (209), a push rod ball screw (213), a push rod ball screw nut (214), a push rod third housing (216) and a push rod output connector (217); The push rod first housing (201) is rotatably connected to the thigh first rotating shaft (102) via the push rod first bearing (202); The driver B (204) is mounted on the first push rod housing (201); The push rod third housing (216) is fixed to the lower end of the push rod second housing (208), and the push rod second housing (208) is connected to the push rod first housing (201) via the push rod second bearing (211); The push rod motor (207) comprises a stator and a rotor, wherein the stator is located inside the push rod first housing (201), the rotor is located inside the stator, and the rotor is fixed on the push rod second housing (208); A push rod ball screw nut (214) is fixed inside the push rod third housing (216), the push rod ball screw nut (214) is sleeved on the push rod ball screw (213), and a push rod output connector (217) is fixed at the end of the push rod ball screw (213); The push rod encoder (209) comprises a magnetic ring and a reader, wherein the magnetic ring is fixed on the push rod second housing (208), and the reader is fixed on the push rod first housing (201).

4. The knee joint with variable stiffness and variable reduction ratio of the humanoid robot according to claim 3, characterized in that: The first connecting rod (300) is in the shape of a straight line and is composed of a first connecting rod structure (301) and a first connecting rod bearing (302); circular holes are provided at both ends of the first connecting rod structure (301), and the first connecting rod bearing (302) is fixed inside the circular holes and is respectively connected to the second rotating shaft (103) of the thigh and the second connecting rod (400).

5. The knee joint with variable stiffness and variable reduction ratio function of the humanoid robot according to claim 4, characterized in that: The second connecting rod (400) is H-shaped and consists of a second connecting rod input shaft (401), a second connecting rod structural member (402) and a second connecting rod bearing (403); circular holes are provided at both ends of the second connecting rod structural member (402), and the second connecting rod bearing (403) is fixed inside the circular holes; the second connecting rod input shaft (401) is provided inside the second connecting rod bearing (403) near one end of the push rod output connecting member (217); the second connecting rod input shaft (401) is sequentially sleeved with the push rod output connecting member (217), the first connecting rod structural member (301) and the second connecting rod structural member (402) from the inside to the outside.

6. The knee joint with variable stiffness and variable reduction ratio of the humanoid robot according to claim 5, characterized in that: The first guide rod (500a) and the second guide rod (500b) are both composed of a guide rod structure, a guide rod bearing and a guide rod input shaft. The guide rod structure is provided with a first circular hole, a second circular hole and a slide groove. The first circular hole is located at the upper end of the guide rod structure, the second circular hole is located in the middle of one side of the guide rod structure, and the slide groove is located in the lower middle part of the guide rod structure. The guide rod bearing is fixed in the first circular hole, and the guide rod input shaft is fixed in the second circular hole. The guide rod bearing is fixed on the shank (700), and the guide rod input shaft is rotatably connected to the inside of the second connecting rod bearing (403) away from the push rod output connecting member (217).

7. The knee joint with variable stiffness and variable reduction ratio of the humanoid robot according to claim 6, characterized in that: The variable stiffness mechanism (600) comprises a stiffness adjustment mechanism first bracket (601), a stiffness adjustment mechanism second bracket (602), a stiffness adjustment mechanism ball screw (605), a stiffness adjustment mechanism guide rail (606), a stiffness adjustment mechanism ball screw nut (607), a stiffness adjustment mechanism guide rail copper sleeve (609), a stiffness adjustment mechanism slider (610), a stiffness adjustment mechanism second bearing (611), a stiffness adjustment mechanism motor (613), a stiffness adjustment mechanism motor output shaft (614), a stiffness adjustment mechanism motor encoder shaft (615) and a stiffness adjustment mechanism motor encoder (617); The first bracket (601) of the rigidity adjustment mechanism and the second bracket (602) of the rigidity adjustment mechanism are fixed to each other to form a support frame of the rigidity variable mechanism (600); The two ends of the rigidity adjustment mechanism ball screw (605) are respectively connected to the interior of the rigidity adjustment mechanism first bracket (601) through the rigidity adjustment mechanism first bearing (604), and the rigidity adjustment mechanism ball screw nut (607) is sleeved on the rigidity adjustment mechanism ball screw (605); one end of the rigidity adjustment mechanism ball screw (605) close to the rigidity adjustment mechanism second bracket (602) is also connected to the rigidity adjustment mechanism motor output shaft (614); A rigidity adjustment mechanism guide rail (606) parallel to the rigidity adjustment mechanism ball screw (605) is also fixed inside the rigidity adjustment mechanism first bracket (601), and the rigidity adjustment mechanism guide rail copper sleeve (609) is sleeved on the rigidity adjustment mechanism guide rail (606); The rigidity adjustment mechanism ball screw (605) and the rigidity adjustment mechanism guide rail (606) are both located inside the rigidity adjustment mechanism slider (610); pivot points are provided on both sides of the rigidity adjustment mechanism slider (610), and the rigidity adjustment mechanism second bearing (611) is sleeved on the pivot points, and the rigidity adjustment mechanism second bearing (611) slides in the slide groove of the guide rod; The rigidity adjustment mechanism motor (613) comprises a stator and a rotor, the rotor is located inside the stator, the stator is located at the upper end of the rigidity adjustment mechanism second bracket (602), an rigidity adjustment mechanism motor output shaft (614) is fixed inside the rotor, and an rigidity adjustment mechanism motor encoder shaft (615) is fixed at the lower end of the rigidity adjustment mechanism motor output shaft (614); The rigidity adjustment mechanism motor encoder (617) comprises a magnetic ring and a reader, wherein the magnetic ring is fixed on the rigidity adjustment mechanism motor encoder shaft (615), and the reader is fixed on the rigidity adjustment mechanism motor pressure cover (616).

8. The knee joint with variable stiffness and variable reduction ratio function of the humanoid robot according to claim 7, characterized in that: The calf (700) comprises a calf structure (701), a first joint shaft (702), a second joint shaft (703), a leaf spring (704) and a driver C (705); the calf structure (701) is U-shaped; the first joint shaft (702) and the second joint shaft (703) are respectively fixed in holes at the upper end of the calf structure (701); the outer sides of the first joint shaft (702) and the second joint shaft (703) are respectively connected to joint bearings (105); the inner sides of the first joint shaft (702) and the second joint shaft (703) are respectively connected to a first guide rod (500a) and a second guide rod (500b); the leaf spring (704) is fixed in a hole in the middle of the calf structure (701); the leaf spring (704) is connected to shafts with keyways on both sides of the second bracket (602) of the rigidity adjustment mechanism; and the driver C (705) is fixed on the calf structure (701).

9. The knee joint with variable stiffness and variable reduction ratio of the humanoid robot according to claim 8, characterized in that: The first guide rod (500a), the second guide rod (500b), the variable stiffness mechanism (600) and the calf (700) constitute a variable stiffness module of the knee joint, and the thigh (100), the push rod (200), the first connecting rod (300), the second connecting rod (400), the first guide rod (500a) and the second guide rod (500b) constitute a variable reduction ratio module of the knee joint.

10. A humanoid robot, characterized in that: A knee joint with variable stiffness and variable reduction ratio functions comprising the knee joint described in any one of claims 1 to 9.

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