Biped robot bionic foot with terrain adaptability and stiffness adjustment

Abstract

The application discloses a kind of bionic feet of biped robot with terrain adaptability and stiffness adjustment, including forefoot, hind foot, bionic locust foot structure, arch piece, six-dimensional force sensor and ankle bracket, arch piece is connected foot and is connected with ankle bracket by six-dimensional force sensor, bionic locust foot structure adopts the composite structure of upper and lower rigid skeleton and bionic locust foot pad, actively adheres irregular ground by liquid bag and flexible bottom surface, realizes multiple point contact, improves friction and grip performance, bionic locust foot pad is equipped with liquid bag partition, simulates human foot pressure distribution, liquid bag can adjust liquid volume, realizes stiffness dynamic adjustment, arch piece adopts arched elastic structure, by cooperating with liquid bag, linkage adjustment arch stiffness is adapted to impact load or gait phase, enhance buffering capacity, again utilize outer ring liquid bag in liquid bag to buffer initial impact, center liquid bag carries main support force, cooperate with arch elastic deformation, reduce impact peak, improve gait stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robots, in particular to a biped robot bionic foot with terrain adaptability and stiffness adjustment. BACKGROUND

[0002] The current humanoid robot foot adopts a rigid structure, and combines force sensors and control algorithms to realize adjustment of landing posture and ground contact force. Some existing technologies use a single air bag structure of flexible foot bottom to realize landing cushioning, increase friction and adapt to uneven terrain, but the use effect is poor. Some high-performance robot feet use toe driving and multi-degree-of-freedom bottom joints to improve the ground adaptability and gait stability of the foot, but the overall cost is high.

[0003] In the publication number: CN106428287B, the name is: flexible leg type robot foot structure containing double cavity air bag toes, which records that it includes a lower leg base, an arch, a fixed rod, a limiting base, a foot, a plate-shaped rubber module, a toe plate, a double cavity air bag and a connecting plate; the arch is fixedly connected with the lower leg base; the upper end of the fixed rod is fixedly connected with the arch, and the lower end is sleeved in the limiting base; the limiting base is fixedly connected with the foot; the top surface and the bottom surface of the plate-shaped rubber module are bolted and fixedly connected with the arch and the toe plate respectively; one end of the connecting plate is hinged with the foot, and the other end is hinged with the toe plate; the double cavity air bag is connected with the bottom surface of the toe plate through a glue layer.

[0004] As shown in the publication number: CN106428287B, the disclosed technology mainly fills compressed air in the air bag. During the walking process of the robot, when the foot bottom is subjected to ground load, the air bag deforms, thereby increasing the contact area with the ground, realizing landing cushioning and improving stability, and the patent also designs rubber blocks between the air bags, and the rubber ground is provided with a person-shaped groove and a long strip-shaped groove, which are used to increase the ground friction and anti-skid performance.

[0005] Although the above structure improves the stability and anti-skid performance of the robot to some extent during walking, it still has the following disadvantages:

[0006] 1. Single region design: mainly through the technology of setting an integral or double cavity air bag on the foot bottom, only providing overall cushioning in the vertical direction and fixed stiffness, lacking the partition stiffness and deformation adjustment ability of different regions of the robot foot bottom, and being difficult to meet the complex pressure distribution requirements of the robot foot bottom;

[0007] 2. Passive adjustment mode: the air bag can only rely on passive compression of air to realize cushioning, and cannot actively adapt to the gait stage or ground conditions, so the adaptability on irregular ground is limited;

[0008] 3. Limited stiffness adjustment range: Lack of adjustment mechanism to change the amount of gas, unable to actively adjust the overall or local stiffness of the foot, leading to insufficient adaptability in complex terrain or different motion scenarios;

[0009] 4. Low structural integration: The existing structure involves the connection and cooperation of multiple components, and the module set degree of the air bag, arch, rubber block and other modules is low, the overall foot structure has large volume and slow response, which is not conducive to lightweight design and modular design;

[0010] 5. Limited friction capacity: Traditional foot bottom anti-skid mostly through simple groove design, lack of friction enhancement mechanism linked with flexible contact surface of foot bottom. SUMMARY

[0011] The technical problem to be solved by the present application is that the stiffness of the existing foot structure cannot be dynamically adjusted, the foot cannot switch or continuously adjust the support stiffness under different loads, different gait stages or different terrain conditions, and under the premise of ensuring compactness and reliability, the linkage between high integration and modular design of flexible bionic foot cannot be realized.

[0012] The existing robot bionic foot cannot adjust the stiffness and deformation of different regions of the foot bottom according to the pressure, the buffer range and the contact area with the ground are limited, it lacks active adaptability to gait stages and ground conditions, and the arch component of the existing robot bionic foot cannot realize dynamic stiffness adjustment linked with the foot bottom.

[0013] In view of the above technical problems, a bionic foot for a biped robot with terrain adaptability and stiffness adjustment is provided, which comprises a forefoot and a hind foot, and further comprises a locust bionic foot structure, an arch piece, a six-axis force sensor and an ankle bracket, one end of the arch piece is connected with the forefoot, the other end is connected with the hind foot, the ankle bracket for connecting with the leg of the robot is connected with the upper end of the arch piece, the six-axis force sensor is installed between the ankle bracket and the arch piece, the six-axis force sensor collects mechanical information at the ankle joint of the robot, the locust bionic foot structure is arranged in the forefoot and the hind foot and contacts with the ground, and the locust bionic foot structure automatically adapts to the shape of the ground and absorbs the impact of landing;

[0014] The locust bionic foot structure comprises a locust bionic foot pad, and a liquid bag is arranged in the locust bionic foot pad.

[0015] Preferably, the locust bionic foot structure further comprises a rigid connecting piece and a rigid pressing ring, the locust bionic foot pad is provided with a connecting skirt, and the locust bionic foot pad is connected with the rigid pressing ring and the rigid connecting piece through the connecting skirt. The setting of the locust bionic foot structure facilitates the flexible and compliant fitting of the irregular ground through the liquid bag and the flexible bottom surface inside the locust bionic foot structure, realizes multi-point contact, increases the contact area, and effectively improves the friction and grip performance.

[0016] In the preferred technical solution of the application, the locust foot pad is fixed between the rigid connecting piece and the rigid pressing ring through the connecting skirt, and the locust foot pad passes through the rigid pressing ring except the connecting skirt and protrudes from the lower surface of the rigid pressing ring, and the whole locust foot pad forms a rigid-flexible-rigid composite connection structure, which can not only buffer the impact force but also provide stable support, and is convenient to use.

[0017] In the preferred technical solution of the application, the liquid tank is connected with the liquid injection port arranged on the locust foot pad, and the liquid tank is filled with fluid, and the amount of fluid in the liquid tank can be controlled and adjusted through the liquid delivery system arranged in the robot and the liquid injection port, and the setting of the liquid tank facilitates the active adjustment of the volume of the liquid tank to realize the automatic adaptation to the ground shape and the absorption of impact force.

[0018] In the preferred technical solution of the application, the outer ring liquid tank is distributed outside the center liquid tank, and the center liquid tank and the outer ring liquid tank are independent of each other and are not connected with each other, and the center liquid tank and the outer ring liquid tank are connected with the outside through one liquid injection port respectively, and such a setting makes the center liquid tank bear most of the vertical supporting load and stiffness adjustment, and the outer ring liquid tank can adapt to the uneven ground, increase the contact area and friction, and improve the stability.

[0019] In the preferred technical solution of the application, the height of the center liquid tank is lower than that of the outer ring liquid tank, and when the bionic foot contacts the ground, the outer ring liquid tank contacts the ground earlier than the center liquid tank, and such a setting makes the outer ring liquid tank preferentially contact the ground in the initial landing stage, plays a role in increasing the contact area and adapting to the terrain fluctuation, and the center liquid tank provides main support to meet the complex pressure distribution requirements of the robot foot bottom and avoid the large deviation of the robot gravity center.

[0020] In the preferred technical solution of the application, the outer ring liquid tank and the center liquid tank are distributed in a multi-convex point and V-shaped arc surface, and such a setting improves the ground adaptation and friction performance of the outer ring liquid tank and the center liquid tank and improves the stability.

[0021] In the preferred technical solution of the application, the viscosity of the fluid injected into the center liquid tank is greater than that of the fluid injected into the outer ring liquid tank, and such a setting makes the center liquid tank provide high-rigidity support, and the outer ring liquid tank can realize flexible deformation and increase the contact area with the ground.

[0022] The arch piece includes an arch middle segment and two elastic bending segments, the elastic bending segments are arranged at two ends of the arch middle segment, and the elastic bending segments are elastically deformed when the bionic foot lands to absorb landing impact. The setting realizes dynamic adjustment of the stiffness of the arch piece within a certain range, meets the differentiated needs of the robot for the foot bottom stiffness in different stages, and realizes the linkage effect of passive buffering and active stiffness adjustment by combining the elasticity of the arch piece itself and the adjustable performance of the locust foot pad.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The technical scheme of the present application uses the locust foot pad provided with a plurality of liquid capsules in the forefoot and the hind foot to refine the foot sub-area and simulate the human foot bottom contact pressure distribution. At the same time, the central liquid capsule and the outer ring liquid capsule are injected with different types or viscosities of liquid, and the liquid volume can be actively adjusted to realize the stiffness partition adjustment of different areas of the foot bottom and realize the real-time adaptation of the stiffness requirement of the robot in the gait cycle.

[0025] The arch piece and the locust foot pad in the foot palm can be linked and controlled. The arch adopts an arched elastic structure, the support height of the two ends is changed by the liquid capsule driving, the deformation of the arch middle segment is caused, the stiffness of the arch is automatically or actively adjusted according to the impact load or the gait stage, the landing buffering capacity is enhanced, and the impact peak is reduced.

[0026] The outer ring liquid capsule provides compliant contact and buffers the initial impact in the initial landing stage, the central liquid capsule bears the main support force subsequently, the transition deviation of the robot gravity center is avoided, the arch piece further absorbs energy by elastic deformation, the staged buffering response is realized, and the gait stability and comfort are improved.

[0027] The locust foot palm is designed in the forefoot and the hind foot, the locust foot palm adopts a modular design and is composed of a three-layer composite structure of a rigid connecting piece, a rigid pressure ring and a liquid capsule, cooperates with a flexible elastomer material and a multi-zone liquid capsule cooperative deformation mechanism to improve the adhesion ability to irregular terrains, the overall structure is compact and simple, the locust foot palm is convenient to integrate into an existing biped robot system, has high engineering realizability and maintainability, and reduces the use cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a perspective view of the present application;

[0029] Figure 2 is a sectional view of the present application;

[0030] Figure 3 is a schematic view of the locust foot pad in the forefoot (perspective state);

[0031] Figure 4 is a schematic view of the locust foot pad in the hind foot (perspective state);

[0032] Figure 5 This is a schematic diagram of the bottom surface of the locust-like footpad.

[0033] Figure 6 This is an exploded view of this application;

[0034] Explanation of reference numerals in the attached diagram: 1-Forefoot, 2-Heelfoot, 3-Locust-inspired foot structure, 31-Rigid connector, 32-Rigid pressure ring, 4-Locust-inspired foot pad, 41-Liquid bladder, 42-Connecting skirt, 43-Central liquid bladder, 44-Outer ring liquid bladder, 45-Injection port, 5-Arch component, 51-Mid-arch section, 52-Elastic bending section, 6-Six-dimensional force sensor, 7-Ankle joint support. Detailed Implementation

[0035] The following will refer to the appendices in the embodiments of the present invention. Figures 1-6 The technical solutions in the embodiments of the present invention will be described in detail below.

[0036] like Figure 1 , Figure 2 and Figure 6 As shown, a bipedal robot bionic foot with terrain adaptability and stiffness adjustment includes a forefoot 1, a hindfoot 2, a locust-inspired foot structure 3, a foot arch 5, a six-dimensional force sensor 6, and an ankle joint support 7.

[0037] The forefoot 1 and the hindfoot 2 are connected by the foot arch component 5. The locust-like foot structure 3 is installed inside the forefoot 1 and the hindfoot 2. The ankle joint support 7 is connected to the foot arch component 5. The six-dimensional force sensor 6 is set between the ankle joint support 7 and the foot arch component 5. The bionic foot as a whole is connected to the robot using the ankle joint support 7.

[0038] The main function of the forefoot 1 and the hindfoot 2 is to serve as the base for the bionic foot, and also as the carrier for the locust-inspired foot structure 3.

[0039] The main function of the locust-like foot structure 3 is to serve as the "sole" of the bionic foot. When in contact with the ground, the locust-like foot structure 3 will actively adapt and deform to adapt to irregular road surfaces, increase the contact area with the ground, and absorb energy to achieve cushioning. The locust-like foot structure 3 has a modular design and can be directly removed and replaced, making it convenient to use.

[0040] The main function of the arch component 5 is to connect the forefoot 1 and the heel 2. At the same time, the arch component 5 has both rigid support and elastic deformation capability. When the bionic foot steps on the ground, the arch component 5 generates deformation, realizing the passive cushioning function of the arch stiffness. In addition, the arch component 5 can also cooperate with the locust-like foot structure 3 to realize the passive cushioning and active adjustment function of the arch stiffness.

[0041] Six-dimensional force sensor 6 is arranged between the arch 5 and the ankle support 7, for real-time acquisition of the robot foot three-axis force and torque, to identify the support phase and contact state, based on the output data information, for the upper layer data feedback to adjust the landing mode, enhance the robot gait stability, six-dimensional force sensor 6 is a direct use of existing products.

[0042] The main role of the ankle support 7 is to connect the foot structure as a whole with the robot lower leg, the ankle support 7 is made of high-strength lightweight aluminum alloy material, and a U-shaped connecting card is arranged on the ankle support 7, the ankle support 7 can be compatible with the existing parallel link or single degree of freedom ankle joint driving structure, connecting the foot structure as a whole with the robot lower leg, convenient to use.

[0043] As shown in Figure 1 , Figure 2 and Figure 6 , the forefoot 1 is a rectangular plate made of metal, a cavity for installing the locust foot structure 3 is recessed in the lower surface of the forefoot 1, the locust foot structure 3 is fixed in the cavity by screws, and in order to facilitate the locust foot structure 3 to contact the ground, part of the surface of the locust foot structure 3 protrudes from the forefoot 1.

[0044] In order to facilitate the injection of fluid into the liquid bag 41 in the locust foot structure 3, a clearance hole is provided on the surface of the forefoot 1 for connecting with the liquid injection port 45 in the liquid bag 41, the liquid injection port 45 extends from the clearance hole and is connected with the liquid delivery system arranged inside the robot.

[0045] The rear foot 2 is the same as the forefoot 1, both are rectangular plates made of metal, and at the same time, the rear foot 2 is also provided with a mounting cavity for installing the locust foot structure 3 and a clearance hole for accommodating the liquid injection port 45.

[0046] Definition: In this embodiment, taking the ground as the reference, after the bionic foot steps on the ground, the surface of the bionic foot in contact with the ground is the lower surface, this direction is downward, and vice versa.

[0047] In order to facilitate the connection of the arch 5 with the forefoot 1 and the rear foot 2, a rectangular groove is provided on the upper surface of the forefoot 1 and the rear foot 2, which is named as a connecting groove, the end of the arch 5 is placed in the connecting groove, and the arch 5 is connected with the forefoot 1 and the rear foot 2 respectively by screws, in addition, the "toe" and "heel" corresponding to the installation of the forefoot 1 and the rear foot 2 are chamfered and smoothed.

[0048] As shown in Figure 1 , Figure 2 and Figure 6As shown, the arch piece 5 includes an arch middle segment 51 and two elastic bending segments 52, the two elastic bending segments 52 are respectively arranged at the two ends of the arch middle segment 51, and the three constitute an arch structure.

[0049] The arch piece 5 is integrally made of a rectangular plate of spring steel or composite material, and the present embodiment preferably uses spring steel. In order to enable the arch piece 5 to have certain rigid support and elastic buffering when the bionic foot lands, the two ends of the arch piece 5 are bent, and the arch piece 5 is in an arch shape after bending.

[0050] The straight segment in the middle is named as the arch middle segment 51, and the bending segments at the two ends are the elastic bending segments 52. In addition, in order to enable the forefoot 1 to imitate the state of human forefoot kicking the ground when the robot walks, the angle between the elastic bending segment 52 connected to the forefoot 1 and the arch middle segment 51 is preferably 120° after bending, and the angle between the elastic bending segment 52 connected to the hindfoot 2 and the arch middle segment 51 is preferably 90° after bending.

[0051] In order to facilitate the connection of the elastic bending segment 52 with the forefoot 1 and the hindfoot 2, a connecting plate is bent at the end of the elastic bending segment 52, the connecting plate can be placed in the connecting groove on the upper surface of the forefoot 1 and the hindfoot 2, and the connecting plate can be fixed in the connecting groove by using screws, thereby realizing the connection of the arch piece 5 with the forefoot 1 and the hindfoot 2.

[0052] As shown in Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 , the locust foot structure 3 includes a rigid connecting piece 31, a rigid pressing ring 32, and a locust foot pad 4, the locust foot pad 4 is arranged between the rigid connecting piece 31 and the rigid pressing ring 32, and the lower surface of the locust foot pad 4 is exposed outside through the rigid pressing ring 32 and contacts the ground when the bionic foot lands.

[0053] The rigid connecting piece 31 is a rectangular metal sheet, and the main function of the rigid connecting piece 31 is to clamp and fix the locust foot pad 4 and connect with the forefoot 1 or the hindfoot 2. Threaded holes for fixing and clearance holes for the liquid injection port 45 of the locust foot pad 4 to pass through are arranged on the surface of the rigid connecting piece 31.

[0054] The rigid pressing ring 32 is a metal ring with the same contour as the rigid connecting piece 31, and an opening is arranged in the middle of the rigid pressing ring 32. After the rigid pressing ring 32 is pressed on the connecting skirt 42 of the locust foot pad 4, the rest of the locust foot pad 4 except the connecting skirt 42 is exposed outside through the opening and contacts the ground when the bionic foot lands.

[0055] The locust foot pad 4 is a rectangular pad made of silicone rubber, the bottom surface of the locust foot pad 4 is in contact with the ground, and a rectangular protrusion is protruded outward from the edge of the locust foot pad 4 for the convenience of connecting the locust foot pad 4 with the rigid connecting piece 31 and the rigid pressing ring 32, and the protrusion is named as a connecting skirt 42, and the locust foot pad 4 is connected with the rigid connecting piece 31 and the rigid pressing ring 32 through the connecting skirt 42.

[0056] The connection between the locust foot pad 4 and the rigid connecting piece 31 and the rigid pressing ring 32: the locust foot pad 4 is clamped between the rigid connecting piece 31 and the rigid pressing ring 32 to form a closed sandwich, the locust foot pad 4 is placed on the surface of the rigid connecting piece 31, and the rigid pressing ring 32 is sleeved on the locust foot pad 4 and in contact with the connecting skirt 42 on the locust foot pad 4, and the three are fixed through fastening screws to form a rigid-flexible-rigid composite connection structure as a whole, which can not only buffer the impact but also provide stable support.

[0057] In order to realize the regional contact and stiffness adjustment of the bionic foot, the locust foot pad 4 is designed in multiple zones, and in order to facilitate zoning, a cavity is provided in the interior of the locust foot pad 4, and the cavity is sealed, at this time the cavity becomes a liquid bag 41 which can be filled with fluid, the liquid bag 41 includes a central liquid bag 43 and an outer ring liquid bag 44, the central liquid bag 43 and the outer ring liquid bag 44 are independent of each other and are not connected with each other, wherein the locust foot pad 4 installed in the hind foot sole 2 has one central liquid bag 43 and one outer ring liquid bag 44, the central liquid bag 43 is located in the middle of the locust foot pad 4, and the outer ring liquid bag 44 is distributed around the central liquid bag 43, the central liquid bag 43 is used to bear most of the vertical support load and stiffness adjustment, and the outer ring liquid bag 44 is used to adapt to uneven ground, increase the contact area and friction.

[0058] The central liquid bag 43 is arranged at the center of the locust foot pad 4 installed in the forefoot sole 1, and there is an outer ring liquid bag 44 at the front end of the forefoot sole 1, the outer ring liquid bag 44 at the front end corresponds to the toe, mainly coping with irregular terrain and lateral support, and there is an outer ring liquid bag 44 on the outer edge part of the forefoot sole 1 close to the arch, the outer ring liquid bag 44 enhances the ground adhesion area and buffering performance in the initial landing and kicking stages, so that the foot contact area and contact pressure distribution are closer to the natural distribution of the human foot sole.

[0059] An injection port 45 which is in communication with the central liquid bag 43 and the outer ring liquid bag 44 is integrally fixed on the surface of the central liquid bag 43 and the outer ring liquid bag 44, the injection port 45 is a circular plastic tube, the central liquid bag 43 and the outer ring liquid bag 44 are connected with an external liquid delivery system through the injection port 45, the liquid delivery system includes a liquid delivery pipeline connected with a micro pump or an electromagnetic valve arranged inside the robot, and the liquid delivery system is an existing device which can be directly used.

[0060] In order to identify the pressure of the ground when in contact with the ground, the pressure sensor is fixed in the center liquid bag 43 and the outer ring liquid bag 44 by using glue, and when the locust foot pad 4 is in contact with the ground, the liquid in the center liquid bag 43 and the outer ring liquid bag 44 will squeeze the pressure sensor, so as to identify the pressure, and the guide of the pressure sensor is connected with the liquid delivery system through the liquid injection port 45.

[0061] The step control system arranged in the robot can actively control the liquid volume and pressure in different liquid bags 41 according to the gait phase and the data obtained by the six-dimensional force sensor 6, so as to form the difference in stiffness distribution.

[0062] Regarding the step control system arranged in the robot: the step control system includes a six-dimensional force sensor 6, a gait estimation module, a liquid adjustment control module and a liquid delivery system (arranged in the robot), wherein the gait estimation module and the liquid adjustment control module are existing mature control units, and the main control process is as follows: the upper master control unit judges whether the current foot is in contact with the ground by reading the feedback of the foot six-dimensional force sensor 6 and the pressure sensor in the liquid bag 41; the gait estimation module identifies the gait phase in combination with the time sequence force data, the speed and the position parameters, including the initial contact period, the support period and the take-off stage; the liquid adjustment control module executes the liquid charging and discharging adjustment operation on the target liquid bag according to the foot area and the load distribution in different stages.

[0063] The specific adjustment strategy of the liquid charging and discharging of the target liquid bag: the liquid bags 41 in the forefoot 1 and the hindfoot 2 are divided into regions according to the force distribution law of the human foot, wherein the liquid bags 41 in the forefoot 1 include the center liquid bag 43, the outer ring liquid bag 44 at the toes and the outer ring liquid bag 44 close to the arch side; the liquid bags 41 in the hindfoot 2 include the center liquid bag 43 and the outer ring liquid bag 44.

[0064] The center liquid bag 43 and the outer ring liquid bag 44 have a rated volume range of 10 mL-50 mL (Vmax), are packaged with flexible materials, have good compression deformation ability and liquid permeability resistance, and are filled with liquid at about 30%-40% of the rated volume in the initial contact stage to enable the center liquid bag 43 and the outer ring liquid bag 44 in the heel 2 to be compliantly contacted with the ground, so that the foot bottom is low-rigidity and helps to absorb impact energy and expand the contact area; in the support stage, the robot weight load is gradually transferred to the support foot, and the longitudinal bearing capacity and stability of the bionic foot are required to be higher, the liquid bag 41 of the heel 2 is controlled to be filled to 70%-85% of the maximum volume, the center liquid bag of the forefoot 1 is controlled to be filled to 60%-80% of the maximum volume, and the liquid volume of the outer ring liquid bag 44 close to the arch side is controlled to be increased to 50%-70% of the maximum volume, so that high-rigidity support is realized in the region, and the overall load bearing capacity and attitude stability are enhanced; in the off-ground stage, the system is overall drained to 10%-20% of the maximum volume, so that the bionic foot rigidity and weight are significantly reduced, energy consumption optimization and flexible gait switching are realized, and the outer ring liquid bag 44 at the toe of the forefoot 1 can be increased to 40%-50% of the maximum volume for a short time to assist in generating elastic propulsion.

[0065] The liquid medium in the embodiment preferably uses silicon oil or water-based mixed liquid with different viscosities and densities, and high-viscosity and low-viscosity liquid combinations can be selected for the center region and the outer ring, so as to further optimize the ground contact buffering performance and variable rigidity response characteristics.

[0066] The center liquid bag 43 and the outer ring liquid bag 44 are independent, and different types of liquid can be injected into the center liquid bag 43 and the outer ring liquid bag 44, for example, high-viscosity or magnetorheological liquid is injected into the center liquid bag 43 to provide high-rigidity support, and low-viscosity or gas-liquid mixture is injected into the outer ring liquid bag 44 to realize compliant deformation and increase the contact area, by injecting different viscosity or different types of liquid into the center liquid bag 43 and the outer ring liquid bag 44, the support rigidity of the region is differentiated, the structural characteristics of the central region of the human foot bottom with high rigidity and the peripheral region with compliance are simulated, the buffering effect is improved, and the walking stability is improved.

[0067] In order to increase the contact area and adapt to the terrain undulation, the ground surface in contact with the locust foot pad 4 is V-shaped concave, and the outer ring liquid bag 44 protrudes from the center liquid bag 43, that is, the outer ring liquid bag 44 contacts the ground first in the initial landing stage, plays a role in increasing the contact area and adapting to the terrain undulation, the center liquid bag 43 contacts the ground later, provides main support, and avoids large deviation of the robot gravity center.

[0068] Regarding the control of the liquid in the locust foot pad 4: the liquid bag 41 can be injected with liquid by a liquid delivery system (including a liquid storage unit, a micro pump, a solenoid valve, a liquid injection port, and a pipeline) according to the partition combination. Based on the gait and sensor data, the control system arranged inside the robot actively adjusts the liquid volume or viscosity inside the central liquid bag 43 and the outer ring liquid bag 44, realizes dynamic and active adjustment of the stiffness of different regions of the foot bottom, and improves the adaptability and stability under complex terrain.

[0069] Regarding the dynamic stiffness adjustment of the locust foot pad 4 and the arch piece 5 linkage: when the liquid bag 41 is filled or drained, the volume and internal pressure change, thereby driving the height of the two end support points of the arch piece 5 to change slightly. When the volume of the liquid bag 41 increases, the two end support points are relatively raised, the deformation amount of the middle segment 51 of the arch is reduced, and the overall stiffness is increased. Conversely, it is reduced. When the liquid volume in the liquid bag 41 is unchanged, the stiffness of the arch can also be adaptively adjusted. Specifically, by utilizing the deformation ability of the liquid bag 41 itself and the external flexible pad layer, under the action of load, the lateral or radial expansion of the liquid bag 41 will cause displacement in the vertical direction, and the deformation amount of the arch piece 5 changes. During this process, the arch structure of the arch piece 5 deforms, changing the overall vertical stiffness. Through active adjustment of the volume of the liquid bag 41, dynamic adjustment of the stiffness of the arch piece 5 within a certain range is realized, meeting the differentiated needs of the foot bottom stiffness at different stages of the robot. The arch structure combines the elasticity of the arch piece 5 itself and the adjustable performance of the liquid bag 41 in the locust foot pad 4, realizing the linkage effect of passive buffering and active stiffness adjustment.

[0070] The technical solution of the present application improves the contact coverage rate and anti-skid ability of the locust foot pad 4 on irregular terrain through the cooperative deformation of the outer ring liquid bag 44 and the central liquid bag 43; the liquid filling state of the outer ring liquid bag 44 and the central liquid bag 43 can be automatically switched according to different gaits; in addition, by adjusting the liquid type and filling amount in different outer ring liquid bags 44 and central liquid bags 43, the high and low stiffness of different regions of the outer ring liquid bag 44 and the central liquid bag 43 is realized, meeting the foot bottom adaptability requirements under complex terrain.

[0071] The above embodiments only illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the present application.

Claims

1. A bionic foot with terrain adaptability and stiffness adjustment for biped robot, comprising a forefoot (1) and a hindfoot (2), characterized in that: The bionic locust foot structure (3), the foot arch piece (5), the six-dimensional force sensor (6) and the ankle bracket (7) are further included. The bionic locust foot structure (3) includes a bionic locust foot pad (4), and the bionic locust foot pad (4) is internally provided with a liquid bag (41). The liquid bag (41) is connected with a liquid injection port (45) arranged on the bionic locust foot pad (4), fluid is injected into the liquid bag (41), and the amount of the fluid in the liquid bag (41) can be controlled and adjusted through a liquid delivery system arranged in the robot and the liquid injection port (45). The outer ring liquid bag (44) is distributed outside the central liquid bag (43), and the central liquid bag (43) and the outer ring liquid bag (44) are independent of each other and are not communicated with each other. The height of the central liquid bag (43) is lower than that of the outer ring liquid bag (44), and when the bionic foot contacts the ground, the outer ring liquid bag (44) contacts the ground earlier than the central liquid bag (43). The viscosity of the fluid injected into the central liquid bag (43) is greater than that of the fluid injected into the outer ring liquid bag (44).

2. The bionic foot with terrain adaptability and stiffness adjustment for biped robot according to claim 1, characterized in that: The bionic locust foot structure (3) further includes a rigid connecting piece (31) and a rigid pressing ring (32), the bionic locust foot pad (4) is provided with a connecting skirt (42), and the bionic locust foot pad (4) is connected with the rigid pressing ring (32) and the rigid connecting piece (31) by means of the connecting skirt (42).

3. The bionic leg with terrain adaptability and stiffness adjustment of the biped robot according to claim 2, characterized in that: The bionic locust foot pad (4) is fixed between the rigid connecting piece (31) and the rigid pressing ring (32) through the connecting skirt (42), and the bionic locust foot pad (4) passes through the rigid pressing ring (32) except the connecting skirt (42) and protrudes from the lower surface of the rigid pressing ring (32).

4. The bionic leg with terrain adaptability and stiffness adjustment of the biped robot according to claim 1, characterized in that: The outer ring liquid bag (44) and the central liquid bag (43) are distributed in a plurality of convex points and V-shaped arc surfaces.

5. The bionic leg with terrain adaptability and stiffness adjustment of the biped robot according to claim 1, characterized in that: The foot arch piece (5) includes a foot arch middle segment (51) and two elastic bending segments (52), the elastic bending segments (52) are arranged at two ends of the foot arch middle segment (51), and the elastic bending segments (52) are elastically deformed when the bionic foot lands to absorb the landing impact.

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