New landing buffer leg

Abstract

The present invention provides a new type of landing buffer leg, including a horizontal drive motor, a fixed bracket, a hip joint drive motor, a knee joint drive motor, a double-drive four-bar transmission mechanism, a landing buffer device and an adaptive terrain foot; the horizontal drive motor is connected to the fixed bracket and rotates and drives the fixed bracket in the horizontal direction; the hip joint drive motor and the knee joint drive motor are fixed on both sides of the fixed bracket and connected to the double-drive four-bar transmission mechanism; the double-drive four-bar transmission mechanism is connected to the adaptive terrain foot through the landing buffer device. The new type of landing buffer leg of the present invention can achieve multiple landing buffers; innovate the leg design to achieve both landing buffers and walking; change the foot design to achieve terrain adaptation; change the whole leg design to reduce the inertia of the leg components.

Description

Technical Field

[0001] The invention relates to the field of mechanical and aerospace engineering, and in particular to a novel landing buffer leg. Background Art

[0002] At present, deep space probes are mostly composed of landers and rovers, but the launch method of a single-function lander carrying a rover is expensive. Although there have been many research results on landers and rovers for lunar and extraterrestrial exploration at home and abroad, the research on integrated probes that can both land and walk is still immature. If an extraterrestrial probe can both land and walk, it can use its own engine to repeatedly land and walk on the surface of an extraterrestrial planet to achieve one launch, multiple landings and walking detections. This will significantly improve the efficiency of extraterrestrial exploration and greatly reduce the cost of exploration.

[0003] The existing buffer legs are basically unable to restore to their original state after a buffer is completed, and are unable to achieve both landing buffering and walking. Few can adapt to different terrains. Specifically, the existing technology mainly has the following problems:

[0004] 1. It is impossible to restore the original state after one buffering is completed. The landing buffer structure mostly adopts spring damping, magnetorheological damping or pure damping, which are all passive buffering designs. Although some of them adopt energy-absorbing structures that can only be used once, they cannot restore the original state after the buffering is completed and then perform the next buffering.

[0005] 2. It is unable to meet the requirements of landing cushioning and walking at the same time. Its structural design mostly only considers the needs of landing, and the structural rigidity is insufficient during walking.

[0006] 3. The influence of different terrains on the star surface is not taken into account. Extraterrestrial star surfaces are mostly craters, craters, slopes, etc. It is very necessary to be able to fit closely to the star surface when landing and walking. Summary of the invention

[0007] In view of the deficiencies in the above-mentioned prior art, the present invention provides a new landing cushioning leg, which can achieve multiple landing cushioning; innovates the leg design to achieve both landing cushioning and walking; changes the foot design to achieve terrain adaptation; and changes the whole leg design to reduce the inertia of the leg components.

[0008] To achieve the above object, the present invention provides a novel landing buffer leg, comprising a horizontal drive motor, a fixed bracket, a hip joint drive motor, a knee joint drive motor, a double-drive four-bar linkage mechanism, a landing buffer device and an adaptive terrain foot; the horizontal drive motor is in transmission connection with the fixed bracket and rotates and drives the fixed bracket in the horizontal direction; the hip joint drive motor and the knee joint drive motor are fixed on both sides of the fixed bracket and are in transmission connection with the double-drive four-bar linkage mechanism; the double-drive four-bar linkage mechanism is connected to the adaptive terrain foot through the landing buffer device.

[0009] Preferably, the double-drive four-bar linkage mechanism comprises a hip joint drive rod, a hip joint link, a knee joint drive rod, a knee joint link and a knee joint; one end of the hip joint drive rod is in transmission connection with the hip joint drive motor, and the other end of the hip joint drive rod is connected to the first end of the hip joint link; one end of the knee joint drive rod is in transmission connection with the knee joint drive motor, and the other end of the knee joint drive rod is connected to the first end of the knee joint link; the second end of the knee joint link is connected to the first end of the knee joint; the second end of the hip joint link is connected to the second end of the knee joint.

[0010] Preferably, the landing buffer device comprises a buffer upper housing, two buffer dampers, a buffer spring and a buffer lower housing; the buffer upper housing is fixedly connected to the second end of the knee joint; the two buffer dampers are arranged in parallel, and the upper parts of the buffer dampers are in frictional connection with the buffer upper housing, and the lower parts of the buffer dampers are fixedly connected to the buffer lower housing by screwing; the buffer spring is arranged between the buffer upper housing and the buffer lower housing; the buffer lower housing is connected to the adaptive terrain foot.

[0011] Preferably, the landing buffer device further comprises two spring ball plungers, two positioning springs and two positioning beads; a clamping groove is formed in the upper part of the buffer damper; screw holes communicated with the corresponding buffer dampers are respectively formed on both sides of the buffer upper housing, and the positions of the screw holes correspond to the clamping groove; the spring ball plungers are respectively screwed into the screw holes; an installation cavity is formed in the spring ball plunger, and a positioning spring is press-fitted and installed in the installation cavity; the positioning bead is pressed into the clamping groove by the positioning spring.

[0012] Preferably, the adaptive terrain foot includes an ankle joint link, a force sensor, a ball joint connector, an ankle joint ball joint, an ankle joint spring, and a foot pad; the ankle joint link is connected to the lower housing of the buffer; the ankle joint link, the force sensor, and the ball joint connector are sequentially fixed by screwing; the ball joint connector is connected to the ankle joint ball joint; the ankle joint ball joint is connected to the foot pad; the ankle joint spring is sleeved outside the ankle joint ball joint and connected between the ball joint connector and the foot pad; the upper part of the ankle joint link is bent at a preset angle.

[0013] Preferably, the fixed bracket includes a first motor fixing plate, a second motor fixing plate, a third motor fixing plate, and a fourth motor fixing plate; the first motor fixing plate and the second motor fixing plate are arranged in parallel; the third motor fixing plate and the fourth motor fixing plate are vertically fixed between the first motor fixing plate and the second motor fixing plate; the hip joint driving motor and the knee joint driving motor are respectively fixed on the third motor fixing plate and the fourth motor fixing plate; the horizontal driving motor is in transmission connection with the first motor fixing plate or the second motor fixing plate.

[0014] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0015] 1. The spring and damper of the landing buffer device are in parallel. During landing buffering, the spring and the damper work simultaneously, and the impact force is reduced by friction and spring contraction; after the buffering is completed, the spring extends to restore the landing buffer structure, and then multiple landings can be achieved. Different from most existing patents, since a single damper cannot achieve excellent buffering effects, such as severe wear and short service life of friction dampers, and the inability to recover of magnetorheological dampers, the use of a parallel spring and damper ensures the buffering effect while streamlining the structure and meets the need for repeated use.

[0016] 2. The use of spring ball plungers ensures both landing buffering and walking. Since the stiffness requirements for the leg structure during landing buffering and walking are different, the buffer leg needs to achieve adaptive stiffness matching. The addition of spring ball plungers solves this problem: when the impact force is less than the threshold value, under the action of the spring ball plungers, the buffer leg presents rigidity and performs the supporting function of the leg during walking; when the impact force exceeds the threshold value, the positioning beads of the spring ball plungers disengage from the card slots formed by the conical surfaces of the guide rail positioners, and landing buffering begins; at the same time, this threshold value can be adjusted through the spring ball plungers. Tightening the spring ball plungers increases the threshold value, and vice versa. The appropriate threshold value can be set by estimating the terrain stiffness and the magnitude of the impact force. The spring ball plungers solve the contradiction between the stiffness requirements of buffering and walking for the leg structure, and avoid the problems of increased inertia, increased energy consumption, and increased cost caused by introducing complex structures; moreover, the effect of the spring ball plungers is adjustable, which means that the impact force threshold value can be set in advance using the ground data obtained by observation, reducing the risk of damage to the detector caused by high threshold values and avoiding the inconvenience of walking caused by low threshold values.

[0017] 3. The passive ball hinge plus spring realizes terrain fitting. When the foot touches the ground, the ball hinge that can rotate at a large angle and the flexible spring can ensure that the sole of the foot fits well with the ground, which is beneficial to the overall stability of the detector during landing and walking. At the same time, it can also buffer the impact force of the ground on the foot to a certain extent during landing; it can meet the fitting requirements of most extraterrestrial surface terrains, improve the adaptability of the detector during surface exploration, reduce the risk of damage to the detector caused by harsh terrain, and at the same time, the small spring can also buffer to a certain extent, reducing the burden on the leg landing buffering structure.

[0018] 4. The double-drive four-link transmission mechanism reduces the leg inertia. Through the ingenious design of the link mechanism, the knee joint drive can be controlled at the detector body part, that is, at the hip joint part, to control the movement of the knee joint, thereby separating the drive component from the leg that needs to move for a long time and in a large range, reducing the moment of inertia of a single leg; by separating the drive component from the moving component, the energy consumption of the moving component is reduced, ensuring that the detector can work more efficiently with limited energy reserves. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the top view of the new landing buffer leg according to the embodiment of the present invention;

[0020] Figure 2 It is the left view of the new landing buffer leg according to the embodiment of the present invention;

[0021] Figure 3 It is the three-dimensional view of the new landing buffer leg according to the embodiment of the present invention;

[0022] Figure 4 It is the three-dimensional view of the landing buffer device according to the embodiment of the present invention;

[0023] Figure 5 It is a front view of a landing cushioning device according to an embodiment of the present invention;

[0024] Figure 6 is a cross-sectional view of a landing cushioning device according to an embodiment of the present invention;

[0025] Figure 7 It is a partial cross-sectional view of a landing cushioning device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] According to the attached figure Figures 1 to 7 , give the preferred embodiments of the present invention, and describe them in detail so that the functions and features of the present invention can be better understood.

[0027] See also Figures 1 to 7 A new type of landing buffer leg in an embodiment of the present invention includes a horizontal drive motor 1, a fixed bracket, a hip joint drive motor 2, a knee joint drive motor 3, a double-drive four-bar transmission mechanism, a landing buffer device and an adaptive terrain foot; the horizontal drive motor 1 is transmission-connected to the fixed bracket and rotates the fixed bracket in the horizontal direction; the hip joint drive motor 2 and the knee joint drive motor 3 are fixed on both sides of the fixed bracket and transmission-connected to the double-drive four-bar transmission mechanism; the double-drive four-bar transmission mechanism is connected to the adaptive terrain foot through the landing buffer device.

[0028] The dual-drive four-bar transmission mechanism includes a hip joint drive rod 6, a hip joint connecting rod 10, a knee joint drive rod 7, a knee joint connecting rod 11 and a knee joint 12; one end of the hip joint drive rod 6 is transmission connected to the hip joint drive motor 2, and the other end of the hip joint drive rod 6 is connected to the first end of the hip joint connecting rod 10; one end of the knee joint drive rod 7 is transmission connected to the knee joint drive motor 3, and the other end of the knee joint drive rod 7 is connected to the first end of the knee joint connecting rod 11; the second end of the knee joint connecting rod 11 is connected to the first end of the knee joint 12; the second end of the hip joint connecting rod 10 is connected to the second end of the knee joint 12.

[0029] The landing buffer device includes a buffer upper shell 13, two buffer dampers 15, a buffer spring 16 and a buffer lower shell 17; the buffer upper shell 13 is fixedly connected to the second end of the knee joint 12; the two buffer dampers 15 are arranged in parallel and the upper part of the buffer damper 15 is frictionally connected to the buffer upper shell 13, and the lower part of the buffer damper 15 is screwed and fixed to the buffer lower shell 17; the buffer spring 16 is arranged between the buffer upper shell 13 and the buffer lower shell 17; the buffer lower shell 17 is connected to the adaptive terrain foot.

[0030] The landing buffer device further includes two spring ball plungers 14, two positioning springs 24 and two positioning beads 25; a clamping groove is formed at the upper part of the buffer damper 15; screw holes communicating with the corresponding buffer dampers 15 are respectively formed on both sides of the upper housing 13 of the buffer, and the positions of the screw holes correspond to the clamping grooves; the spring ball plungers 14 are respectively screwed into the screw holes; an installation cavity is formed in the spring ball plunger 14, and a positioning spring 24 is press-fitted and installed in the installation cavity; the positioning bead 25 is pressed into the clamping groove by the positioning spring 24.

[0031] The motion model of the landing buffer device is as follows:

[0032] The whole landing process is simplified to a single-degree-of-freedom forced vibration process of a mass m under the action of an impact force F, a spring f and a damper c. At the same time, the impact force F is simplified to a pulse excitation, and the equation is as follows:

[0033]

[0034] The initial conditions are

[0035]

[0036] The pulse excitation actually gives an impulse to the mass, that is, an initial velocity. So the problem is equivalent to a single-degree-of-freedom free vibration process with an initial velocity

[0037]

[0038] The initial conditions become

[0039]

[0040] The general solution of the single-degree-of-freedom free vibration is

[0041]

[0042] Substituting the initial conditions gives the forced vibration under unit pulse excitation

[0043]

[0044] Since the magnitude of the impact force is F, so it is actually

[0045]

[0046] There is an exponentially decaying part in the displacement of the mass, indicating that under the combined action of the spring and the damper, the detector can quickly stabilize during landing; finally, it decays to 0, indicating that under the action of the spring, the landing buffer leg returns to its original state and can perform the next landing.

[0047] The spring ball plunger 14 maintains the overall stiffness model:

[0048] Taking the positioning bead 25 of the spring ball plunger 14 as the research object, there is

[0049] F k -N1cosθ - N2cosθ = 0

[0050] Where F k is the thrust of the positioning spring 24 of the spring ball plunger 14 on the positioning bead 25, and its magnitude is determined by the degree of compression of the positioning spring 24. There is

[0051] F k = kΔx

[0052] N1 and N2 are the pressures of the two conical surfaces of the guide rail damper on the positioning bead 25, and θ is the inclination angle of the conical surface generatrix, with a magnitude of 30°

[0053] According to Newton's third law, N′1 and N′2 are the interaction forces with N1 and N2 respectively, that is, they are equal in magnitude and opposite in direction

[0054] N′1 = N1, N′2 = N2

[0055] Taking the guide rail damper as the research object, there is

[0056] N′1 cosθ + N′2 cosθ - N = 0

[0057] The maximum static friction force between the guide rail damper and the housing is

[0058] f s = μ s N

[0059] Where N and f s are the pressure of the housing on the guide rail damper and the maximum static friction force respectively, and μS is the maximum static friction coefficient of the housing material and the guide rail damper material

[0060] Finally, we get

[0061] f s = μ s kΔx

[0062] When the impact force F impact < f s , the landing buffer as a whole presents rigidity, that is, the walking mode; when the impact force F impact > f s , the damper moves relative to the housing, and the buffering is completed through friction and spring contraction.

[0063] The adaptive terrain foot includes an ankle joint linkage 18, a force sensor 19, a ball joint connector 20, an ankle joint ball hinge 21, an ankle joint spring 22, and a foot pad 23; the ankle joint linkage 18 is connected to the lower housing 17 of the buffer; the ankle joint linkage 18, the force sensor 19, and the ball joint connector 20 are sequentially screwed and fixed; the ball joint connector 20 is connected to the ankle joint ball hinge 21; the ankle joint ball hinge 21 is connected to the foot pad 23; the ankle joint spring 22 is sleeved outside the ankle joint ball hinge 21 and is connected between the ball joint connector 20 and the foot pad 23; the upper part of the ankle joint linkage 18 is bent at a preset angle.

[0064] The fixing bracket includes a first motor fixing plate 8, a second motor fixing plate 9, a third motor fixing plate 4, and a fourth motor fixing plate 5; the first motor fixing plate 8 and the second motor fixing plate 9 are arranged in parallel; the third motor fixing plate 4 and the fourth motor fixing plate 5 are vertically fixed between the first motor fixing plate 8 and the second motor fixing plate 9; the hip joint driving motor 2 and the knee joint driving motor 3 are respectively fixed on the third motor fixing plate 4 and the fourth motor fixing plate 5; the horizontal driving motor 1 is in transmission connection with the first motor fixing plate 8 or the second motor fixing plate 9.

[0065] In a novel landing buffer leg according to an embodiment of the present invention, the core components of the driving module are three driving motors: a horizontal driving motor 1, a hip joint driving motor 2, and a knee joint driving motor 3. Under the restriction of the first motor fixing plate 8 and the second motor fixing plate 9, the hip joint driving motor 2 and the knee joint driving motor 3 fixed on the third motor fixing plate 4 and the fourth motor fixing plate 5 respectively rotate horizontally around the output shaft of the horizontal driving motor 1.

[0066] The main effect of the double-drive four-bar linkage mechanism is to enable the hip joint driving motor 2 and the knee joint driving motor 3 located in the detector body part to drive the upper and lower parts of the leg, and complete leg movements such as stretching the leg, bending the leg, and lifting the leg, which play roles in both the landing mode and the walking mode.

[0067] The landing buffer device is the key to achieving multiple landing buffering: Under the action of positioning spring 24 positioned inside spring ball plunger 14, positioning bead 25 stuck in the slot of buffer damper 15 increases the static friction force between buffer damper 15 and the upper housing 13 of the buffer, and this static friction force is the impact force threshold for the buffer device to maintain rigidity (its magnitude can be adjusted by screwing spring ball plunger 14 in or out); When the detector lands, its legs will be subjected to a great impact force (exceeding the set threshold), at this time, positioning bead 25 cannot hold buffer damper 15, resulting in the upper housing 13 of the buffer approaching the lower housing 17 of the buffer along the guide rail of buffer damper 15, and the friction force between buffer damper 15 and the upper housing 13 of the buffer and buffer spring 16 both play a buffering role; Since the impact force during landing is an instantaneous force, after landing, the force on the legs is only gravity (less than the elastic force of buffer spring 16 after being compressed), under the elastic force of buffer spring 16, the upper housing 13 and the lower housing 17 of the buffer separate and return to their original state, and can perform another landing buffering;

[0068] The function of the adaptive terrain foot is mainly to better fit the surface of the celestial body. Since the surface terrain of the planet is complex, including craters, rocky areas, highlands, etc., these will all hinder the movement of the detector, and at the same time, the subsidence of the detector in the soil on the surface of the planet will also have an adverse impact on the detection task. The ball joint connector 20, ankle joint ball joint 21, and ankle joint spring 22 of the adaptive terrain foot can make the footpad 23 always touch the ground with the bottom surface of the foot, and at the same time, the footpad 23 has a certain area, which can avoid the subsidence of the detector in most terrains. The said adaptive terrain foot is beneficial for the detector to adapt to complex terrain environments, ensures the intelligence and adaptability of the detector when facing complex terrains, and meets the requirements of large-scale exploration of the extraterrestrial surface.

[0069] A new type of landing buffer leg according to an embodiment of the present invention works as follows:

[0070] 1. First, estimate the magnitude of the landing impact force according to the observed terrain and landform of the celestial body surface to be detected, and set the distance that spring ball plunger 14 is screwed into the upper housing 13 of the buffer, that is, set the impact force threshold;

[0071] 2. During landing, ankle joint ball joint 21 rotates and ankle joint spring 22 bends to ensure that footpad 23 touches the ground with the bottom surface of the foot;

[0072] 3. Under the action of the impact force, positioning bead 25 disengages from the slot of buffer damper 15, and the upper housing 13 of the buffer approaches the lower housing 17 of the buffer along the guide rail of buffer damper 15, and the friction force between buffer damper 15 and the upper housing 13 of the buffer and the elastic force of buffer spring 16 play a buffering effect;

[0073] 4. After landing is completed, the elastic force of the buffer spring 16 after being compressed is greater than the pressure of the detector on the leg. Under the action of the elastic force of the buffer spring 16, the upper buffer housing 13 and the lower buffer housing 17 are separated and restored to their original state, and can perform landing buffering again;

[0074] 5. On the star map, the hip joint drive motor 2 and the knee joint drive motor 3 complete leg movements such as lifting the leg, and the horizontal drive motor 1 completes the horizontal forward and backward movement of the leg, that is, walking is achieved;

[0075] 6. The detector makes a leap under the action of its own drive module to smoothly pass through terrains such as craters, rocky areas, and highlands, and can perform landing buffering again.

[0076] The present invention has been described in detail with reference to the accompanying drawings and embodiments. Those of ordinary skill in the art can make various variations to the present invention according to the above description. Therefore, some details in the embodiments should not constitute a limitation to the present invention, and the protection scope of the present invention will be defined by the scope of the appended claims.

Claims

1. A novel landing buffer leg, characterized in that, The invention comprises a horizontal drive motor (1), a fixed support, a hip joint drive motor (2), a knee joint drive motor (3), a double-drive four-bar transmission mechanism, a landing buffer device and an adaptive terrain foot; the horizontal drive motor (1) is connected to the fixed support in a driving manner and rotates the fixed support in a horizontal direction; the hip joint drive motor (2) and the knee joint drive motor (3) are fixed to two sides of the fixed support and are connected to the double-drive four-bar transmission mechanism; the double-drive four-bar transmission mechanism is connected to the adaptive terrain foot via the landing buffer device; The dual-drive four-link transmission mechanism comprises a hip joint drive rod (6), a hip joint connecting rod (10), a knee joint drive rod (7), a knee joint connecting rod (11) and a knee joint (12); one end of the hip joint drive rod (6) is transmission-connected to the hip joint drive motor (2), and the other end of the hip joint drive rod (6) is connected to the first end of the hip joint connecting rod (10); one end of the knee joint drive rod (7) is transmission-connected to the knee joint drive motor (3), and the other end of the knee joint drive rod (7) is connected to the first end of the knee joint connecting rod (11); the second end of the knee joint connecting rod (11) is connected to the first end of the knee joint (12); and the second end of the hip joint connecting rod (10) is connected to the second end of the knee joint (12); The landing buffer device comprises a buffer upper shell (13), two buffer dampers (15), a buffer spring (16) and a buffer lower shell (17); the buffer upper shell (13) is fixedly connected to the second end of the knee joint (12); the two buffer dampers (15) are arranged in parallel, and the upper part of the buffer damper (15) is frictionally connected to the buffer upper shell (13), and the lower part of the buffer damper (15) is screwed and fixed to the buffer lower shell (17); the buffer spring (16) is arranged between the buffer upper shell (13) and the buffer lower shell (17); the buffer lower shell (17) is connected to the adaptive terrain foot The landing buffer device further comprises two spring ball plungers (14), two positioning springs (24) and two positioning beads (25); a slot is formed on the upper part of the buffer damper (15); screw holes communicating with the corresponding buffer damper (15) are respectively formed on both sides of the buffer upper shell (13), and the positions of the screw holes correspond to the slots; the spring ball plungers (14) are respectively screwed into the screw holes; the spring ball plungers (14) form an installation cavity, in which a positioning spring (24) is press-installed; and the positioning bead (25) is pressed into the slot by the positioning spring (24).

2. The novel landing buffer leg according to claim 1, wherein The adaptive terrain foot comprises an ankle joint connecting rod (18), a force sensor (19), a ball joint connecting piece (20), an ankle joint ball joint (21), an ankle joint spring (22) and a foot pad (23); the ankle joint connecting rod (18) is connected to the buffer lower shell (17); the ankle joint connecting rod (18), the force sensor (19) and the ball joint connecting piece (20) are screwed and fixed in sequence; the ball joint connecting piece (20) is connected to the ankle joint ball joint (21); the ankle joint ball joint (21) is connected to the foot pad (23); the ankle joint spring (22) is sleeved outside the ankle joint ball joint (21) and connected between the ball joint connecting piece (20) and the foot pad (23); the upper part of the ankle joint connecting rod (18) is bent at a preset angle.

3. The novel landing buffer leg according to claim 2, characterized in that, The fixing bracket comprises a first motor fixing plate (8), a second motor fixing plate (9), a third motor fixing plate (4) and a fourth motor fixing plate (5); the first motor fixing plate (8) and the second motor fixing plate (9) are arranged in parallel; the third motor fixing plate (4) and the fourth motor fixing plate (5) are vertically fixed between the first motor fixing plate (8) and the second motor fixing plate (9); the hip joint driving motor (2) and the knee joint driving motor (3) are respectively fixed on the third motor fixing plate (4) and the fourth motor fixing plate (5); and the horizontal driving motor (1) is drivingly connected to the first motor fixing plate (8) or the second motor fixing plate (9).

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