CN114852212B - Foot buffer device of humanoid robot - Google Patents

Foot buffer device of humanoid robot Download PDF

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Publication number
CN114852212B
CN114852212B CN202210680625.1A CN202210680625A CN114852212B CN 114852212 B CN114852212 B CN 114852212B CN 202210680625 A CN202210680625 A CN 202210680625A CN 114852212 B CN114852212 B CN 114852212B
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foot
metatarsal
calcaneus
connecting rod
bone
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CN114852212A (en
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陈学超
张锦涛
余张国
韩连强
高志发
杜嘉恒
黄强
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Beijing Institute of Technology BIT
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Beijing Institute of Technology BIT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D57/00—Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track
    • B62D57/02—Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track with ground-engaging propulsion means, e.g. walking members
    • B62D57/032—Vehicles characterised by having other propulsion or other ground- engaging means than wheels or endless track, alone or in addition to wheels or endless track with ground-engaging propulsion means, e.g. walking members with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • F16F15/04—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means
    • F16F15/06—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems using elastic means with metal springs

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Manipulator (AREA)

Abstract

The invention discloses a foot buffering device of a humanoid robot, wherein the upper part of a metatarsal joint part of a toe can be rotatably connected with one end of a instep plate spring; the metatarsal joint component is rotatably connected with one end of the metatarsal connecting rod; the navicular block is fixedly connected with the other end of the instep plate spring and can be rotatably connected with the other end of the metatarsal connecting rod; the instep plate spring is arranged at the upper part of the metatarsal connecting rod in parallel; the calcaneus part and the scaphoid are rotatably connected through two groups of calcaneus connecting rods; two ends of the arch spring damper are respectively hinged with the calcaneus part and the metatarsal bone connecting rod. The device imitates the physiological structure of human feet and has an arch structure; the foot arch spring damper and the instep plate spring are arranged, and a buffering effect is generated by utilizing the linkage relation of the foot and the tension action of the two springs; and provides three different stiffness states for foot landing, improves energy efficiency and adapts to complex terrain.

Description

Foot buffer device of humanoid robot
Technical Field
The invention relates to the technical field of biped humanoid robots, and particularly provides a foot buffering device of a humanoid robot.
Background
In the walking process of the biped robot, the feet are difficult to avoid being impacted, and the walking stability of the robot can be seriously influenced by overlarge impact force, so that the foot of the robot is very important to buffer and absorb shock. Most of the existing foot buffer devices for humanoid robots use spring dampers to absorb impact energy, such as springs disposed on the ankles of the robots, axial buffering of the feet of the robots using link mechanisms, and springs disposed on the heels and the front soles, respectively.
The invention patent CN 114148428A discloses a multifunctional damping bionic foot, a main body of the device is provided with a bionic foot distance, a bionic heel, a bionic foot sole and the like, the bionic foot distance and the bionic foot sole are connected through a plate spring, meanwhile, the heel part is provided with a wave spring, and the foot has certain buffering and damping capacity. However, the device lacks the corresponding flexibility, is in large plane contact with the ground, and does not have the bone ligament linkage characteristics similar to the real human foot.
The invention patent CN 102556202A discloses a foot buffer device based on a four-bar mechanism, which mainly utilizes a linear compression spring and a four-bar tension mechanism to provide elastic passive force, when a foot touches the ground, the four-bar mechanism is compressed, and the corresponding spring positioned in the four-bar mechanism is stretched to generate tension, store certain energy and relieve impact force to a certain extent. However, the mechanism is only point contact with the ground, which is not beneficial to the stability of the robot, and the space occupied by the four-bar diamond mechanism is too large, so that the leg structure is not compact enough, the number of the springs is large, and the requirements of various support rigidity of foot touchdown can not be met.
The invention patent CN 111959634A discloses a bionic foot shock absorption device, which is provided with spring dampers at the front and the rear, and when the front sole or the rear sole lands on the ground, the impact force can be absorbed by the spring dampers. However, the motion profile is too simple for this device, the motion of the foot is merely pivoting about a hinge, no corresponding flexible cushioning is provided when the foot is subjected to axial forces, and the device lacks stiffening characteristics.
All the above modes can play a certain role in buffering, but still have some disadvantages: 1. the linkage relation of the feet is insufficient and cannot be compared favorably with the physiological structure of a real person; 2. the structure of the foot is not compact enough, and the assembly on the robot is heavy; 3. it is unable to adapt to rugged terrain and various complex terrains.
Disclosure of Invention
In order to solve the deficiency that exists among the prior art, this application has proposed a foot buffer of humanoid robot, through the physiology structure of imitative people's foot, utilizes the linkage of foot to produce buffering effect, through reasonable arrangement spring mechanism for the device is compacter, and the device has multiple contact rigidity with ground, well adapts to complicated topography.
The technical scheme adopted by the invention is as follows:
a humanoid robot foot cushioning device comprising:
a metatarsal joint component, the upper part of which is rotatably connected with one end of the instep plate spring; the metatarsal joint component is rotatably connected with one end of the metatarsal connecting rod;
the navicular bone block is fixedly connected with the other end of the instep plate spring and can be rotatably connected with the other end of the metatarsal bone connecting rod; the instep plate springs are arranged at the upper parts of the metatarsal connecting rods in parallel;
the calcaneus part is rotatably connected with the scaphoid block through two groups of calcaneus connecting rods; and two ends of the arch spring damper are respectively hinged with the calcaneus component and the metatarsal bone connecting rod.
Furthermore, the instep plate spring is composed of a plate spring and rubber coated on the upper side and the lower side of the plate spring; a strain gauge is provided on the surface of the plate spring.
Further, the scaphoid block comprises a scaphoid block main body, three groups of scaphoid bearing seats are arranged on the scaphoid block main body, a mandrel and a scaphoid bearing can be rotatably arranged in each group of scaphoid bearing seats, and a metatarsal connecting rod or a calcaneus connecting rod is fixedly sleeved outside the mandrel; the navicular bearing seat axially limits the outer ring of the navicular bearing through the inner hole shoulder and the outer top cover to form a fixing part, the mandrel penetrates through the inner ring of the navicular bearing, and the baffle, the inner ring of the navicular bearing, the connecting end of the metatarsal bone connecting rod or the calcaneus bone connecting rod and the mandrel are fixedly abutted by fasteners to form a rotating part together.
Further, the metatarsophalangeal joint part comprises a metatarsophalangeal joint block, the lower surface of the metatarsophalangeal joint block is flat, and at least one metatarsophalangeal joint connecting plate is arranged above the metatarsophalangeal joint block in the sagittal plane direction; the metatarsophalangeal joint connecting plate is sleeved outside the pin through a metatarsophalangeal joint bearing; the pin is fixed to the instep leaf spring by the outer post, the inner post, and the fastener.
Furthermore, a metatarsal joint bearing seat is arranged on the upper surface of the metatarsal joint block, a mandrel and a bearing outside the mandrel are installed on the metatarsal joint bearing seat, and one end of the metatarsal connecting rod is sleeved outside the mandrel.
Furthermore, the calcaneus part comprises at least two calcaneus blocks which are oppositely arranged and connected through three groups of cylindrical pins; wherein, the calcaneus bearing and the calcaneus connecting rod are sleeved on two adjacent groups of cylindrical pins; and an arch spring damper is sleeved on the other group of cylindrical pins.
Further, a front foot encoder is arranged at the joint of the navicular bone block and the metatarsal bone connecting rod; a hindfoot encoder arranged at the joint of the calcaneus part and the navicular bone block; the rotors of the front foot encoder and the rear foot encoder are respectively connected with the baffle at the installation position.
Furthermore, front foot pressing plates are respectively paved on the upper surface and the lower surface of the instep plate spring at the joints of the instep plate spring and the outer upright post and the inner upright post, and a middle foot pressing plate is paved at the joint of the instep plate spring and the scaphoid main body.
Furthermore, a front sole trigger switch is arranged on the metatarsus joint block, a switch bracket is fixedly connected with the bottom of the calcaneus block, and a rear sole trigger switch is arranged on the switch bracket.
Further, when the heel touches down, rigidity is provided by the serial connection of the arch spring damper and the instep plate spring; when the whole sole lands, the foot arch spring damper and the instep leaf spring are connected in parallel to provide rigidity; the stiffness is provided only by the instep leaf spring when the forefoot is at ground level.
The invention has the beneficial effects that:
the invention mainly aims at the problem of foot touchdown buffering of the biped robot in the walking process, and simulates the physiological structure of the foot bones and ligaments of a human body. The navicular bone blocks in the device correspond to the navicular bone, the cuneiform bone and the talus bone structure of the human foot; the metatarsophalangeal joint component corresponds to the structure of the metatarsus and the metatarsophalangeal joint of the human; the calcaneus part corresponds to a human calcaneus structure; the arch spring damper corresponds to the human plantar fascia. The arrangement of the structure of the front foot, the middle foot and the rear foot of the humanoid robot enables the springs to generate different connection relations at different touchdown stages to play different roles, and then three different contact stiffnesses are generated by utilizing the connection conditions of the springs in different touchdown states, so that the characteristics of the variable stiffness of the feet in the walking process similar to a human are realized, the bionic degree of the feet of the robot is improved, the energy efficiency is improved, and the environment adaptability is improved.
According to the bionic touchdown buffering device with the flexible shock absorption and variable-rigidity contact functions, the adaptability and stability of the robot to a complex environment are improved. Different from the existing foot buffer device of the humanoid robot, the foot buffer device realizes the bionic buffer and the variable stiffness characteristic of the foot through the linkage relation among all parts and the reasonable spring arrangement design, and simultaneously provides three types of ground contact stiffness for different ground contact states in the walking process, thereby adapting to different passive force requirements in the gait process.
The foot has compact structure and strong adaptability to complex environment, fully imitates the physiological structure of human foot, has three parts of forefoot, midfoot and hindfoot, can adapt to rugged ground, and the spring and the connecting rod in the device are arranged by ligament bones of the human foot; the front foot and the rear foot are hinged on the middle foot, the front foot is provided with a plate spring structure, and a spring damper is connected between the front foot and the rear foot; the plate spring is of a sandwich structure, wraps the rubber damping outer layer, and is internally provided with a strain sensor.
According to the rigidity change when the front and rear soles land during walking, the device is provided with an arch spring damper and an instep leaf spring, and can provide three types of ground contact rigidity: when the heel touches the ground, the rigidity is provided by serially connecting the arch spring damper and the instep leaf spring; when the sole lands on the ground, the arch spring damper and the instep plate spring are connected in parallel to provide rigidity; the stiffness is provided only by the instep leaf spring when the forefoot is at ground level.
The device can provide certain support flexibility, reduce the ground impact in the process of touching down the earth, and the bionic arch structure has better buffer capacity.
Drawings
FIG. 1 is a schematic view of a foot cushioning device of a humanoid robot according to the present invention;
FIG. 2 is a side view of a foot cushioning device of a humanoid robot of the present invention;
FIG. 3 is a sectional view of the structure at J1 and J2 in FIG. 2;
FIG. 4 is a cross-sectional view of the hinge structure at J8 of FIG. 2;
FIG. 5 is a cross-sectional view of the sandwich construction of the instep spring;
FIG. 6 is a schematic view of the heel structure;
FIG. 7 is a cross-sectional view of the J4 hinge structure of FIG. 2;
fig. 8 is a three-dimensional view of the metatarsal joint piece 7 c;
FIG. 9 is a three-dimensional view of the navicular bone block;
FIG. 10 is a ground-contacting stiffness diagram of a foot cushioning device;
FIG. 11 is a schematic diagram of a foot cushioning device based humanoid robot touchdown detection;
in the figure, 1, a rear foot encoder, 2, a navicular bone, 2a, a baffle, 2b, a navicular bone main body, 2c, a mandrel, 2d, a navicular bone bearing, 2e, a top cover, 2f, a navicular bone bearing seat, 3, a front foot encoder, 4, a middle foot pressure plate, 5, a instep leaf spring, 5a, a strain gauge, 5b, a rubber cladding, 5c, a carbon fiber plate spring core, 6, a front foot pressure plate, 7, a metatarsal joint component, 7a, an outer upright post, 7b, a pin, 7c, a metatarsal joint block, 7d, a metatarsal joint bearing, 7e, a gasket, 7f, an inner upright post, 7g, a metatarsal joint connecting plate, 7h, a metatarsal joint bearing seat, 8, a metatarsal connecting rod, 9, an arch spring damper, 10, a calcaneus component, 10a calcaneus connecting rod, 10b, a calcaneus bearing, 10c, an outer calcaneus bone block, 10d, a gasket, 10e, 10f, an inner heel switch bone block, 10f, a switch bracket, 10g, and a trigger.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The bones of the human foot can be divided into forefoot, midfoot and hindfoot. The forefoot contains 5 metatarsals, more specifically the big toe consisting of 1 metatarsal and 2 phalanges, and the lateral 2 nd, 3 rd, 4 th, 5 th metatarsal consisting of 1 metatarsal and 3 phalanges. The midfoot is composed of navicular, medial cuneiform, lateral cuneiform, medial cuneiform and cuboid bones. The hindfoot is composed of calcaneus and talus tissue, the talus being located above the calcaneus and the midfoot forming a joint that maintains the presence of the arch of the foot.
The invention designs a foot buffer device of a humanoid robot as shown in figure 1 by fully referring to the bone ligament structure of the human foot, and the device is divided into a front foot, a middle foot and a rear foot. Wherein: the forefoot part comprises a metatarsophalangeal joint part 7, a dorsum plate spring 5 and a metatarsal connecting rod 8; the middle foot part comprises a scaphoid block 2; the hindfoot portion is the calcaneus component 10; an arch spring damper 9 is connected between the metatarsal links 8 and the calcaneus component 10.
Hereinafter, the three structures of the forefoot, the midfoot and the hindfoot of the present apparatus will be described in detail.
The midfoot part is the core pivot of the device and comprises a scaphoid block 2; the scaphoid block 2 is structured as shown in fig. 9, the scaphoid block 2 includes a scaphoid block main body 2b, three sets of scaphoid bearing seats 2f are arranged on the scaphoid block main body 2b, each set of scaphoid bearing seat 2f is composed of at least 2 cylindrical parts, a bearing mounting hole is arranged inside each cylindrical part for mounting a bearing and a mandrel 2c, and a hole step and the like are arranged for limiting axial movement of the bearing. With particular reference to FIG. 3, each set of scaphoid bearing blocks 2f of the present application is formed of 3 opposing annular segments, so that 2 mandrels 2c can be installed between the three annular segments. Since the right mandrel 2c and the left mandrel 2c are axisymmetric, only the right mandrel 2c in fig. 3 will be described as an example; an annular bulge, namely a hole shoulder, is arranged on the inner ring of the annular part in the middle of the scaphoid bearing seat 2f and abuts against the outer ring of the scaphoid bearing 2d on the right side, and threads are arranged on the inner wall of the opening of the scaphoid bearing seat 2f (on the left side) and can be in threaded connection with the top cover 2e through the threads, so that the top cover 2e abuts against the outer ring of the scaphoid bearing 2d on the left side, and the scaphoid bearing 2d is limited on the scaphoid bearing seat 2 f; dabber 2c passes two navicular bearing 2 d's inner circle, and dabber 2 c's right-hand member sets up cyclic annular flange, and the left side is fixed with baffle 2a through the fastener, and the flange is two bearings on the right side of butt respectively with baffle 2a for dabber 2c can be spacing by the axial, prescribes a limit to dabber 2c on navicular bearing 2d from this. Meanwhile, the metatarsal link 8 (or the calcaneus link 10 a) is fitted around the spindle 2c, and both left and right end faces of the annular flange of the metatarsal link 8 (or the calcaneus link 10 a) abut against inner rings of the left and right scaphoid bearings 2d, respectively, whereby the metatarsal link 8 (or the calcaneus link 10 a) is restricted to the spindle 2c. In summary, the stem 2c and the scaphoid bearing 2d and the metatarsal bar 8 (or the calcaneus bar 10 a) outside the stem 2c can be limited to the scaphoid bearing seat 2f, and a relative rotation structure can be formed in which the metatarsal bar 8, the stem 2c, the inner ring of the scaphoid bearing 2d, and the baffle plate 2a are used as rotation parts, and the outer ring of the scaphoid bearing 2d, the scaphoid bearing seat 2f, the top cover 2e, and the scaphoid block body 2b are used as fixing parts.
As can be seen from fig. 2, a first set of scaphoid bearing seats 2f on the scaphoid block body 2b is used for hinging with the metatarsal connecting rod 8 to form a hinge J1, a second set of scaphoid bearing seats 2f is used for hinging with one part of the calcaneus part 10 to form a hinge J2, and a second set of scaphoid bearing seats 2f is used for hinging with the other part of the calcaneus part 10 to form a hinge J3. A rear foot encoder 1 is arranged at the hinged part of the scaphoid block 2 and the calcaneus part 10, and a front foot encoder 3 is arranged at the hinged part of the scaphoid block 2 and the metatarsal bone connecting rod 8; the coder is fixedly connected with the navicular block main body 2b through a fastener (such as a screw), and a rotor of the coder is connected with the baffle 2 a; when the forefoot or the hind foot is pressed and deformed, the metatarsal connecting rod 8 or the calcaneus part 10 drives the spindle 2c to rotate, the spindle 2c is fixed on the navicular bone block 2 through the bearing 2d, the top cover 2e is abutted against the bearing 2d, the baffle 2a is fixed at the tail end of the spindle 2c through the screw to form a rotating part together, and the rotating part rotates along with the spindle, and the specific structure is shown in fig. 4.
The forefoot part mainly comprises a metatarsophalangeal joint part 7, a instep plate spring 5 and a metatarsal connecting rod 8; the structure of the metatarsophalangeal joint part 7 is shown in fig. 4 and 8, the metatarsophalangeal joint part 7 comprises a metatarsophalangeal joint block 7c, the lower surface of the metatarsophalangeal joint block 7c is flat, 2 metatarsophalangeal joint connecting plates 7g are arranged in the upper sagittal plane direction of the metatarsophalangeal joint block 7c, and the 2 metatarsophalangeal joint connecting plates 7g are parallel to each other; the 2 metatarsophalangeal joint connecting plates 7g are provided with through holes, and the two through holes are positioned on the same axis. An outer upright post 7a and an inner upright post 7f are respectively arranged on two sides of each metatarsal joint connecting plate 7g, the outer upright post 7a and the inner upright post 7f are connected through a pin 7b, a metatarsal joint bearing 7d is sleeved on the pin 7b, and the pin 7b and the metatarsal joint bearing 7d are placed in a through hole of the metatarsal joint connecting plate 7g, so that the metatarsal joint block 7c can rotate around the pin 7b (forming a hinge J8). The outer upright post 7a and the inner upright post 7f are fixedly connected with the instep leaf spring 5 through fasteners, specifically, threaded holes for connection are formed in the upper portions of the outer upright post 7a and the inner upright post 7f, the instep leaf spring 5 is overlapped on the upper portions of the outer upright post 7a and the inner upright post 7f, and one end of the instep leaf spring 5 is fixedly connected with the outer upright post 7a and the inner upright post 7f through bolts; the other end of the instep leaf spring 5 is also fixedly connected to the navicular block body 2b by a bolt. In the present application, the forefoot pressing plates 6 may be laid on the upper and lower surfaces of the instep plate spring 5 connected to the columns (the outer column 7a and the inner column 7 f), respectively, and the pressures applied by the bolts may be made more uniform by the forefoot pressing plates 6. Similarly, the middle foot pressing plate 4 can be laid at the joint of the scaphoid main body 2b, and the pressure exerted by the bolts can be more uniform through the middle foot pressing plate 4.
The upper surface of the metatarsus joint block 7c is also provided with a metatarsus joint bearing seat 7h, the structure of the metatarsus joint bearing seat 7h is similar to that of the navicular bone bearing seat 2f, namely, the metatarsus joint bearing seat 7h consists of 3 opposite cylindrical parts, a mandrel and a bearing outside the mandrel can be arranged among the three cylindrical parts, and the mandrel and the bearing on the mandrel can be positioned by adopting a baffle plate, a top cover and the like. One end of the metatarsal link 8 is fitted over the spindle 2c, thereby enabling articulation (forming a hinge J7) between the metatarsal link 8 and the metatarsal joint component 7.
The structure of the instep plate spring 5 is as shown in fig. 5, the instep plate spring 5 is a composite structure, and is formed by wrapping a plate spring 5c of a glass fiber structure by upper and lower layers of rubber 5b, the structure of the instep plate spring 5 has elasticity and certain damping, unexpected oscillation is avoided, strain gauges 5a are respectively arranged between the plate spring 5c and the upper and lower layers of rubber 5b, the magnitude of the bending moment of the instep plate spring 5 can be detected by using the strain gauges 5a, and the stress condition of the forefoot part is estimated approximately.
Because one end of the metatarsal connecting rod 8 is hinged with the navicular bone block 2, the other end of the metatarsal connecting rod 8 is hinged with the metatarsal joint part 7, the metatarsal joint part 7 is also hinged with one end of the instep plate spring 5, and the other end of the instep plate spring 5 is fixedly connected with the navicular bone block 2, the instep plate spring 5, the metatarsal connecting rod 8, the metatarsal joint block 7 and the navicular bone block 2 jointly form a closed movement chain containing a flexible body (namely the instep plate spring 5).
The metatarsal joint block 7c may be provided with a forefoot trigger switch mounting hole for mounting the forefoot trigger switch, as shown on the right side in fig. 2.
In the process of foot movement, when the metatarsal joint block 7c of the toe touches the ground and is pressed, the metatarsal connecting rod 8 is driven to rotate, meanwhile, the instep leaf spring 5 bends upwards, and the generated elastic force hinders the further deformation of the forefoot part, so that the device has certain supporting and buffering functions. The hindfoot portion provides another point of resilient support for the entire ball of the foot, and the calcaneus component 10 shown in figures 6 and 7 includes an outer calcaneus piece 10c and an inner calcaneus piece 10e; in this application, outer calcaneus piece 10c, interior calcaneus piece 10e respectively have 2, and 2 outer calcaneus pieces 10c set up respectively in 2 pieces of both sides with piece 10e, and four are parallel to each other and the setting of certain distance of interval. The adjacent outer calcaneus bone block 10c and the inner calcaneus bone block 10e are connected through cylindrical pins, the middle parts of the cylindrical pins are smooth cylinders, and the two ends of the cylindrical pins are fixedly connected with the outer calcaneus bone block 10c and the inner calcaneus bone block 10e through threads respectively. On each cylindrical pin, a calcaneus bearing 10b is sleeved outside the cylindrical pin between the adjacent outer calcaneus block 10c and the inner calcaneus block 10e, so that a calcaneus connecting rod 10a can be arranged on each cylindrical pin, and the other end of the calcaneus connecting rod 10a is hinged with the navicular block 2. Instead of a cylindrical pin, a screw (or nut) of appropriate length may be used, the screw passing through the external heel bone piece 10c, the spacer 10d, the bearing 10b, and having the other end fixed in the thread of the internal heel bone piece 10 e.
In 3 cylindricals, the calcaneus connecting rod 10a on 2 cylindricals that are adjacent all articulates with navicular piece 2, forms the parallelogram structure through calcaneus connecting rod 10a between inside and outside calcaneus piece 10c, 10e and the navicular piece 2, and inside and outside calcaneus piece 10c, 10e can be around navicular piece 2 translation within a certain limit promptly.
The other 1 cylindrical pin is hinged with one end of an arch spring damper 9 (forming a hinge J5), and the other end of the arch spring damper 9 is connected with a metatarsal bone connecting rod 8 (forming a hinge J6); the arch spring damper 9 is used to limit the range of motion of the calcaneus component to a limited range of motion. The formed arch has certain tension and connects the front and rear foot parts into a whole to provide elastic supporting force for the whole sole. The bottom of the heel bone block 10e in the 2 blocks is fixedly connected with a switch bracket 10f, and the switch bracket 10f is provided with a rear sole trigger switch 10g.
In this embodiment, both ends of the metatarsal bar 8 and the calcaneus bar 10a are cylindrical, and the cylindrical portions can be fitted over the spindle 2c and the bearing, respectively, during assembly.
The heel often lands first in the biped robot carries out imitative people's walking motion, consequently this device utilizes the nimble motion of calcaneus part, also can realize certain buffering effect.
The principle diagram of the foot cushioning device of the humanoid robot designed by the present application for changing rigidity to touch the ground is explained with reference to the attached drawing 10:
because the foot of the real person lands during walking and has the rigidity changing performance, the robot touchdown device can detect three states of the front sole landing, the rear heel landing and the full sole landing, and can provide different rigidities in the three touchdown states.
When the sole of the foot of the robot lands on the ground, due to the special configuration of the metatarsal joint part 7, the instep plate spring 5 bends upwards, the metatarsal bone connecting rod 8 rotates around the hinge J1, and due to the fact that the arch spring damper 9 is connected with the calcaneus part 10 and the metatarsal bone connecting rod 8, the calcaneus part 10 also generates corresponding follow-up, and the rigidity between the ankle part and the ground of the robot is determined by the rigidity of the instep plate spring 5 and the special configuration of the metatarsal bone part 7, and a first rigidity characteristic K1 is obtained; when the whole sole lands, the instep leaf spring 5 bends upwards, meanwhile, the heel part 10 also moves upwards, and the arch spring damper 9 is stretched, so that the instep leaf spring 5 and the arch spring damper 9 are stressed in parallel, and a second rigidity K2 is generated for an ankle; when the heel of the robot lands on the ground, the calcaneus part 10 moves in a translation mode due to the fact that the calcaneus connecting rod 10a is of a parallelogram structure, the arch spring damper 9 is connected with the calcaneus part 10 and the metatarsal connecting rod 8, when the metatarsal connecting rod 8 moves under the tension of the arch spring damper 9, the instep plate spring 5 is driven to bend downwards, and the rigidity between the ankle joint and the ground is the rigidity K3 generated by the fact that the arch spring damper 9 and the instep plate spring 5 are connected in series.
Aiming at the characteristics of low bionic degree, insufficient buffering capacity, poor adaptability to complex environment, excessively large structural arrangement and the like of the existing bionic foot buffering device. The bionic touchdown buffer device with the functions of flexible shock absorption, variable-rigidity contact and the like is designed by imitating the physiological structure of foot bones and ligaments of a human body, and the adaptability and stability of the robot to a complex environment are improved. Different from the existing foot buffer device of the humanoid robot, the foot buffer device realizes the bionic buffer and the variable stiffness characteristic of the foot through the linkage relation among all parts and the reasonable spring arrangement design, and simultaneously provides three types of ground contact stiffness for different ground contact states in the walking process, thereby adapting to different passive force requirements in the gait process.
The forefoot trigger switch, the rear foot trigger switch, the strain gauge 5a, the forefoot encoder 3 and the rear foot encoder 1 which are arranged on the foot buffer device can be in signal connection with the processor, so that data (such as v', theta) collected by the forefoot trigger switch, the rear foot trigger switch, the strain gauge 5a, the forefoot encoder 3 and the rear foot encoder 1 can be further processed 2 ′、θ 1 ′、s 1 、s 2 ) And inputting the data into a processor.
In the processor, the humanoid robot touchdown detection can be carried out according to the collected data, and the detection method comprises the following steps:
1. touchdown detection
As shown in fig. 11, considering the conventional working condition of the robot, the lower limbs of the robot have two steps of suspension swing and grounding support. Defining the robot to have the following states when the foot is suspended: the angle of the forefoot encoder is theta 1 The angle of the hindfoot encoder is theta 2 The output voltage of a strain bridge (consisting of the strain sheets 5 a) of the strain sheet 5a is v, the front foot bottom trigger switch and the rear foot bottom trigger switch are both in an off state, and the state of the switches is recorded as s 1 ＝s 2 And =0. These quantities are scalar quantities and can be considered as reference or initial values for detection. When the foot touches the ground, the plate spring is bent according to the buffer mechanism of the device, the voltage of the strain bridge is changed into v', the encoder data is correspondingly changed, and the angle of the forefoot encoder is theta 1 ', the angle of the hindfoot encoder is theta 2 ', and the sole trigger switch is turned on, and is marked as s 1 ＝s 2 And =1. Although the data change of the two encoders is different due to different landing posturesNo matter what way the sole lands, namely, the front sole lands, the rear heel lands and the full sole lands do not need to be distinguished, the following touchdown judgment function can be established:
f(t)＝k 1 (v-v′)+k 2 (θ 2 ′-θ 1 ′-θ 2 +θ 1 )+k 3 (θ 1 -θ 1 ′) 2 +k 4 (θ 2 -θ 2 ′) 2 +k 5 s 1 +k 6 s 2
taking into account the different dimensions between the different terms in the formula, coefficients are introduced to balance the order of magnitude between the individual physical quantities, in which formula the fusion weight k 1 、k 2 、k 3 、k 4 、k 5 、k 6 The touchdown judgment function f (t) represents the result of multi-sensor fusion, and whether the foot lands can be judged by setting a reasonable fusion weight coefficient for f (t) and setting a certain threshold value M for the final fusion value, wherein the touchdown judgment function f (t) represents the result of multi-sensor fusion and is represented as follows:
Figure BDA0003698237270000081
the first term k in the formula 1 (v-v') indicating that the foot deflection direction is limited, when the plate spring is bent upwards, the signal of the strain bridge takes a positive value, so that the first term in the formula is positive, and therefore, the sensor fusion value is guided to be increased, so that the touchdown judgment result is more inclined to judge that touchdown is performed; similarly, when the leaf spring is bent upward, the signal of the strain bridge takes a negative value, and the first term in the equation is negative, thereby leading to a decrease in the fusion value, so that the result of determination of touchdown is more likely to determine that touchdown is not yet made. Second term k in the formula 2 (θ 2 ′-θ 1 ′θ 2 +θ 1 ) Indicating the tension of the arch spring damper, which is stretched when the foot lands, causing this increase and leading the determination to be more inclined to determine touchdown. The third term k in the formula 3 (θ 1 -θ 1 ′) 2 And the fourth term k 4 (θ 2 -θ 2 ′) 2 Respectively representing front and rear foot codesChanges in the readings of the device, whether the foot is on the forefoot or heel, can cause the encoder data to deviate from the initial position, making touchdown determination more likely to determine touchdown. The fifth term k in the formula 5 s 1 And the sixth term k 6 s 2 Representing a change in the sole trigger switch, which is turned on when the foot is grounded, causing the fifth sixth term to change toward a positive value, making the fusion function more inclined to determine that touchdown has occurred. The fusion weight k corresponding to each item 1 、k 2 、k 3 、k 4 、k 5 、k 6 The value of (2) can be properly adjusted, and the influence of the corresponding item in the touchdown judgment function is changed by adjusting the value of each item fusion weight, for example, when the requirement is reduced
When the foot is in a suspended state, the voltage of the strain bridge in the formula does not generate differential voltage, the data of the encoder also changes in a small range, meanwhile, the foot trigger switch is not conducted, and each item of the touchdown judgment function is a very small positive real number; when the foot lands, at least one item in the formula changes to cause the judgment function to increase, the weight coefficients of different items reflect the dependence degree of the judgment result on different sensing information, and the larger the weight of the item is, the more trusting the related sensor information of the item to judge the contact; finally, a reasonable threshold value is set for a touchdown judgment function, and the suspended state and the foot touchdown state are distinguished: and when the touchdown judgment function is smaller than the threshold value, judging that the foot is not landed, and when the touchdown judgment function is larger than the threshold value, judging that the foot is landed. In conclusion, the method and the device change the degree of dependence of the judgment result on certain sensor data by reasonably configuring the weight coefficients and the judgment threshold values of different sensors.
2. Judging the landing part
Namely, the front sole, the whole sole or the heel is touched. The application provides a fuzzy decision-making judgment method, which carries out fuzzy judgment on data of two encoders, takes a real-time angle and a reference angle of the encoders as basic input of fuzzy reasoning, and decides to obtain a foot landing part by making a specific fuzzy rule.
Fuzzification treatment: consider theta 1 ′-θ 1 As fuzzy input quantity, in the interval [ - σ ] 1min ，σ 1max ]The internal blurring is negative big, negative small, positive big, respectively
Figure BDA0003698237270000091
In the same way, the angle theta 2 ′-θ 2 Fuzzification, in the interval [ - σ ] 2min ，σ 2max ]The internal blurring is negative big, negative small, positive big, the range is
Figure BDA0003698237270000092
H represents the foot-flat state, which is taken as fuzzy output and is in the interval [ -L ] min ，L max ]The internal mold is pasted to the heel, the partial rear sole, the whole sole, the partial front sole and the toe respectively
Figure BDA0003698237270000093
Figure BDA0003698237270000094
Wherein- σ 1min 、σ 1max Respectively the forefoot encoder angle theta 1 Minimum and maximum values of (d); σ 2min ，σ 2max Respectively, the hindfoot encoder angle theta 2 Minimum and maximum values of; -L min ，L max Respectively showing the position of the heel and the ball of the foot relative to the ankle.
The input membership function is generated by adopting a Gaussian method, and can be expressed as:
Figure BDA0003698237270000101
wherein G (x, sigma, c) is a Gaussian membership function, the result represents the membership of the element in the fuzzy set, and sigma and c respectively represent the variance and mean of the Gaussian membership function.
Fuzzy rule and reasoning:
Ifθ′ 1 -θ 1 = positive and θ' 2 -θ 2 = positive, H = toe-on-ground;
Ifθ′ 1 -θ 1 = positive and θ' 2 -θ 2 = positive small, H = toe-on-ground;
Ifθ′ 1 -θ 1 = positive and θ' 2 -θ 2 = minus small, H = forward sole landing;
Ifθ′ 1 -θ 1 = positive and θ' 2 -θ 2 = minus large, H = full sole landing;
Ifθ′ 1 -θ 1 = normal small and theta' 2 -θ 2 = positive, H = toe-on-ground;
Ifθ′ 1 -θ 1 = positive small and θ' 2 -θ 2 = positive small, H = toe-on-ground;
Ifθ′ 1 -θ 1 = normal small and theta' 2 -θ 2 = minus, H = full sole landing;
Ifθ′ 1 -θ 1 = normal small and theta' 2 -θ 2 = minus large, H = rear sole landing;
Ifθ′ 1 -θ 1 'minus small and theta' 2 -θ 2 = right, H = front sole landing;
Ifθ′ 1 -θ 1 =negativesmall and theta' 2 -θ 2 = positive small, H = full sole landing;
Ifθ′ 1- θ 1 'minus small and theta' 2 -θ 2 = minus small, H = heel strike;
Ifθ′ 1 -θ 1 'minus small and theta' 2 -θ 2 = minus large, H = heel strike;
Ifθ′ 1 -θ 1 = negative big and theta' 2 -θ 2 = positive, H = full sole landing;
Ifθ′ 1 -θ 1 = negative big and θ' 2 -θ 2 = positive small, H = rear sole landing;
Ifθ′ 1 -θ 1 = negative big and theta' 2 -θ 2 = minus small, H = heel strike;
Ifθ′ 1 -θ 1 = negative big and theta' 2 -θ 2 = negative large, H = heel strike;
the foot landing part can be judged by carrying out fuzzy reasoning on the data of the two encoders through the rules, and then the output result is [ -L ] after defuzzification processing min ，L max ]The real number of the interval has no clear physical meaning, so the reasoning result after defuzzification is further divided to obtain three intervals of the piecewise function, wherein the three intervals are respectively
Figure BDA0003698237270000102
Figure BDA0003698237270000103
TABLE 1 representation of foot landing state
Figure BDA0003698237270000104
Figure BDA0003698237270000111
The foot contact can be described as four cases of no contact, forefoot contact, heel contact, and full foot contact, and thus the contact state can be represented by two-digit binary numbers according to table 1: the sole is not on the ground 00, the front sole is on the ground 01, the rear heel is on the ground 10, and the whole sole is on the ground 11. When the output result after defuzzification is in
Figure BDA0003698237270000112
When the distance is within the interval, judging that the foot part is the heel landing, and returning the bionic foot to the robot controller with the flag bit of 1; when the output result after defuzzification is in
Figure BDA0003698237270000113
When the bionic foot returns to the robot controller, the flag bit is 2; when the output result after defuzzification is in
Figure BDA0003698237270000114
When the area is within the range, the foot is judged to be full sole landing, and the bionic foot returns to the robot controller flag bit to be 3. And finally, judging the touchdown state. In this application, the landing state output by the method is represented using binary, which is converted into a decimal identifier to be returned to the robot controller. Aiming at the encoder information of the device, corresponding fuzzy rules are designed after fuzzification, and the foot bottom touchdown part is judged, so that the states of the foot sole touchdown, the heel touchdown and the foot sole touchdown of the foot can be distinguished. The contact state of the foot is represented by binary, so that the representation method is more concise, and the zone bit returned to the robot controller is more intuitive.
The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.

Claims (10)

1. A foot cushioning device of a humanoid robot, comprising:
a metatarsal joint component (7), wherein the upper part of the metatarsal joint component (7) is rotatably connected with one end of the instep plate spring (5); the metatarsophalangeal joint component (7) is rotatably connected with one end of a metatarsal connecting rod (8);
the scaphoid block (2), the scaphoid block (2) is fixedly connected with the other end of the instep plate spring (5), and the scaphoid block (2) is rotatably connected with the other end of the metatarsal bone connecting rod (8); the instep plate spring (5) is arranged at the upper part of the metatarsal connecting rod (8) in parallel;
the calcaneus component (10), the calcaneus component (10) and the scaphoid block (2) are rotatably connected through two groups of calcaneus connecting rods (10 a); two ends of the arch spring damper (9) are respectively hinged with the calcaneus component (10) and the metatarsal bone connecting rod (8).
2. The foot cushioning device of the humanoid robot of claim 1, characterized in that the instep plate spring (5) is composed of a plate spring (5 c) and rubber (5 b) coated on the upper and lower sides of the plate spring (5 c); a strain gauge (5 a) is provided on the surface of the leaf spring (5 c).
3. The humanoid robot foot cushioning device of claim 1, wherein the navicular bone (2) comprises a navicular bone main body (2 b), three groups of navicular bone bearing seats (2 f) are arranged on the navicular bone main body (2 b), a mandrel (2 c) and a navicular bone bearing (2 d) are rotatably arranged in each group of navicular bone bearing seats (2 f), and the connecting end of the metatarsal bone connecting rod (8) or calcaneus bone connecting rod (10 a) is fixedly sleeved outside the mandrel (2 c); the scaphoid bearing seat (2 f) axially limits the outer ring of the scaphoid bearing (2 d) through an inner hole shoulder and an outer top cover (2 e) to form a fixing part, the mandrel (2 c) penetrates through the inner ring of the scaphoid bearing (2 d), and the baffle (2 a), the inner ring of the scaphoid bearing (2 d), the connecting end of the metatarsal bone connecting rod (8) or the calcaneus connecting rod (10 a) and the mandrel (2 c) are fixedly abutted by fasteners to form a rotating part together.
4. A foot cushioning device for a humanoid robot as claimed in claim 1, characterized in that, the foot cushioning device for a humanoid robot as claimed in claim 1, wherein the metatarsophalangeal joint member (7) comprises a metatarsophalangeal joint block (7 c), the lower surface of the metatarsophalangeal joint block (7 c) is flat-plate-shaped, and at least one metatarsophalangeal joint connecting plate (7 g) is provided in the sagittal plane direction above the metatarsophalangeal joint block (7 c); the metatarsal joint connecting plate (7 g) is sleeved outside the pin (7 b) through a metatarsal joint bearing (7 d); the pin (7 b) is fixed to the instep leaf spring (5) by an outer column (7 a), an inner column (7 f) and a fastener.
5. The foot buffer device of the humanoid robot of claim 4, characterized in that the metatarsophalangeal joint bearing seat (7 h) is arranged on the upper surface of the metatarsophalangeal joint block (7 c), the metatarsophalangeal joint bearing seat (7 h) is provided with a mandrel and a bearing outside the mandrel, and one end of the metatarsal connecting rod (8) is sleeved outside the mandrel.
6. The foot cushioning device of the humanoid robot of claim 4, characterized in that the calcaneus bone part (10) comprises at least two calcaneus bone blocks, the calcaneus bone blocks are oppositely arranged and are connected with each other through three groups of cylindrical pins; wherein, the calcaneus bearing (10 b) and the calcaneus connecting rod (10 a) are sleeved on two adjacent groups of cylindrical pins; and an arch spring damper (9) is sleeved on the other group of cylindrical pins.
7. A humanoid robot foot cushioning device as claimed in claim 3, characterized by a forefoot encoder (3) provided at a junction of the navicular mass (2) and the metatarsal bone connecting rod (8); a hindfoot encoder (1) arranged at the joint of the calcaneus part (10) and the scaphoid block (2); the rotors of the front foot encoder (3) and the rear foot encoder (1) are respectively connected with the baffle (2 a) at the installation position.
8. The foot cushioning device of the humanoid robot as claimed in claim 4, characterized in that, at the joints of the instep plate spring (5) with the outer upright (7 a) and the inner upright (7 f), the forefoot pressing plates (6) are respectively laid on the upper and lower surfaces of the instep plate spring (5), and the middle foot pressing plate (4) is laid at the joint with the navicular mass body (2 b).
9. The foot cushioning device of a humanoid robot as claimed in claim 6, characterized in that the forefoot trigger switch is mounted on the metatarsal joint block (7 c), the switch bracket (10 f) is fixedly connected to the bottom of the calcaneus block, and the rear forefoot trigger switch (10 g) is mounted on the switch bracket (10 f).
10. A humanoid robot foot cushioning device as claimed in claim 1, characterized in that, when heel is grounded, stiffness is provided by an arch spring damper (9) and an instep leaf spring (5) in series; when the sole is fully landed, the arch spring damper (9) and the instep plate spring (5) are connected in parallel to provide rigidity; the sole plate spring (5) provides stiffness only when the forefoot is on the ground.
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