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CN-121990077-A - Variable-rigidity metatarsophalangeal joint based on torsion spring and connecting rod combination and foot type robot

CN121990077ACN 121990077 ACN121990077 ACN 121990077ACN-121990077-A

Abstract

The invention relates to a variable-rigidity metatarsophalangeal joint based on a torsion spring and connecting rod combination and a foot-type robot, wherein the variable-rigidity metatarsophalangeal joint comprises a rear sole, a front sole, a metatarsophalangeal joint rotating shaft, a torsion spring, a connecting rod, a stay bar and a driving module; the front sole is rotationally connected with the rear sole through a rotating shaft of the metatarsophalangeal joint; the support pull rod is connected to the driving module and the connecting rod, the spring coil of the torsion spring is sleeved on the rotating shaft of the metatarsophalangeal joint, the torsion spring is hinged with the other end of the connecting rod, the other end of the torsion spring is connected with the front sole, the driving module is fixedly arranged on the rear sole and used for driving the support pull rod to slide back and forth along the rear sole, the support pull rod slides to drive the spring coil of the torsion spring to rotate forwards or backwards around the rotating shaft of the metatarsophalangeal joint through the connecting rod so as to drive the front sole to do dorsiflexion or plantarflexion movement relative to the rear sole, and the support pull rod enables the torsion spring to generate different torsion angles at different sliding positions when the front sole is subjected to external force and changes the rigidity of the metatarsophalangeal joint, so that dorsiflexion and plantarflexion movement can be actively realized, and simultaneously the support pull rod has rigidity and angle adjusting capability.

Inventors

  • XIAO KE
  • CHEN XIAOQI
  • ZHANG GONG

Assignees

  • 超级机器人研究院(黄埔)
  • 华南理工大学

Dates

Publication Date
20260508
Application Date
20260309

Claims (10)

  1. 1. The variable stiffness metatarsophalangeal joint based on the combination of the torsion spring and the connecting rod is characterized by comprising a rear sole, a front sole, a metatarsophalangeal joint rotating shaft, the torsion spring, the connecting rod, a stay bar and a driving module; The front sole is rotationally connected with the rear sole through a rotating shaft of the metatarsophalangeal joint; one end of the stay bar is connected with the driving module, the other end is hinged with one end of the connecting rod, The spring coil of the torsion spring is sleeved on the rotating shaft of the metatarsophalangeal joint, one end of the torsion spring is hinged with the other end of the connecting rod, and the other end of the torsion spring is connected with the front sole; The driving module is fixedly arranged on the rear sole and used for driving the stay bar to slide back and forth along the rear sole; The spring coils of the torsion springs are driven to rotate forwards or reversely around the rotating shaft of the metatarsophalangeal joint by the sliding of the stay bars through the connecting rods, so that the front sole is driven to extend backwards or bend plantarly relative to the rear sole, and meanwhile, the stay bars are arranged at different sliding positions, so that the torsion springs generate different torsion angles when the front sole is subjected to external force, and the rigidity of the metatarsophalangeal joint is changed.
  2. 2. The variable stiffness metatarsophalangeal joint based on a combination of torsion springs and links according to claim 1, wherein the torsion springs comprise a left-handed torsion spring and a right-handed torsion spring arranged side by side on the axis of rotation of the metatarsophalangeal joint.
  3. 3. The variable stiffness metatarsophalangeal joint based on a torsion spring and connecting rod combination according to claim 1, further comprising a stiffness adjusting slider slidingly connected to the rear sole, wherein one end of the stay rod is connected to the stiffness adjusting slider, and the driving module is connected to the stiffness adjusting slider for driving the stiffness adjusting slider to slide reciprocally along the rear sole.
  4. 4. The variable stiffness metatarsophalangeal joint based on the torsion spring and connecting rod combination according to claim 1, wherein the rear sole is provided with a chute and a first guide through hole, the stiffness adjusting slider slides in the chute, and the first guide through hole penetrates the rear sole along the length direction and is used for accommodating and guiding the stay bar to slide.
  5. 5. The variable stiffness metatarsophalangeal joint based on the combination of the torsion spring and the connecting rod according to claim 1, wherein the front sole is provided with a second guide through hole, and the other end of the torsion spring is inserted into the second guide through hole and can extend and retract along the axial direction of the second guide through hole.
  6. 6. The variable stiffness metatarsophalangeal joint based on the torsion spring and connecting rod combination according to claim 1, wherein an upper concave platform, a lower concave platform and a restraining groove are arranged at one end of the rear sole close to the front sole, the upper concave platform is used for being contacted with the front sole when the front sole is stretched to a preset maximum angle so as to limit the continuous back stretching, the lower concave platform is positioned below the upper concave platform and is used for being contacted with the connecting rod when the front sole is plantar flexed to the preset maximum angle so as to limit the continuous plantar flexing, dead points of a connecting rod mechanism are avoided, a centering platform is arranged at one side of the front sole close to the rear sole, and is embedded in the restraining groove so as to limit the transverse deflection of the front sole relative to the rear sole.
  7. 7. The variable stiffness metatarsophalangeal joint based on the combination of the torsion spring and the connecting rod according to claim 6, further comprising a torsion spring inner limit ring, wherein the torsion spring inner limit ring is fixedly arranged on a rotating shaft of the metatarsophalangeal joint and positioned in the torsion spring coil to form an inner space limit of the torsion spring for limiting radial offset of a central axis of the spring coil relative to the axis of the rotating shaft of the metatarsophalangeal joint and transverse offset of a front sole, two sides of a restraining groove of a rear sole are respectively provided with an outer convex platform corresponding to the outer convex platform of the rear sole, the front sole is provided with an outer side offset platform, one side of the outer side offset platform facing the rear sole is provided with an inner concave arc surface, and an outer space limit of the torsion spring is formed between the outer convex platform and the inner concave arc surface.
  8. 8. The variable stiffness metatarsophalangeal joint based on the torsion spring and connecting rod combination according to claim 7, wherein the torsion spring inner limit ring is of a stepped shaft structure and comprises a support section matched with the inner wall of the spring coil and an avoidance section which is positioned at the end part of the support end and has an outer diameter smaller than that of the support section, an avoidance chamfer is arranged on the periphery of the end part of the support section, the support section is used for radially limiting the spring coil, and the avoidance section and the avoidance chamfer form an avoidance space together and are used for providing a release space for the end part ring of the spring coil when the spring coil is subjected to torsion deformation so as to prevent the spring coil from reverse torsion failure caused by constraint overtightening.
  9. 9. The variable stiffness metatarsophalangeal joint based on a torsion spring and connecting rod combination according to any one of claims 1 to 8, wherein the driving module is a telescopic linear motor, the motor body of which is fixedly connected with the rear sole, and the telescopic rod of which is connected with one end of the stay rod as the driving end.
  10. 10. A foot robot comprising a robot body and a variable stiffness metatarsophalangeal joint based on a torsion spring and link combination as claimed in any one of claims 1 to 9 disposed on the foot of the robot body.

Description

Variable-rigidity metatarsophalangeal joint based on torsion spring and connecting rod combination and foot type robot Technical Field The invention relates to the technical field of bionic engineering, in particular to a variable-rigidity metatarsophalangeal joint and foot type robot based on torsion spring and connecting rod combination. Background Foot robots, particularly biped humanoid robots, are a research hotspot in the robot field due to their great potential for seamless access in human life and work environments. The core challenge is to achieve stable, efficient, natural and highly environmentally adapted dynamic movements. Research shows that the metatarsophalangeal joint of the human foot plays a crucial role in gait cycle, not only bears larger moment, but also presents low rigidity to buffer impact through the rigidity-variable characteristic of the metatarsophalangeal joint, and presents high rigidity to efficiently transfer energy in the propulsion stage, so that rolling type advancing of heel, sole and toe is realized, and energy efficiency is remarkably optimized. Early bipedal robots generally used a rigid sole with a single degree of freedom, and completely ignored the function of the metatarsophalangeal joints, for control simplicity. This simplified design results in stiff gait, high energy consumption and poor adaptability to uneven ground. To solve this problem, researchers have made continuous improvements, generally through the following stages: In the passive flexible joint stage, elastic elements such as springs and the like (such as ROBIAN robots) are introduced at the front sole rotating shaft, so that the joint has certain passive buffering and energy storage capacity. For example, the pace of HRP-2 is significantly improved after adding a passive forefoot. However, the rigidity of such mechanisms is fixed and cannot be adapted to the dynamic demands of different movement patterns such as walking, running, jumping, etc. for rigidity. In the active joint driving stage, a motor is adopted to directly drive the front sole to move (such as a LOLA robot), so that active dorsiflexion and plantarflexion of the joint are realized, and the flexibility is high. However, the scheme has the inherent defects of large energy consumption, response lag, heavy mechanism, poor impact resistance and the like, and limits the performance of the scheme in practical application. The active and passive combined rigidity-variable joint stage is the current main stream research direction, and aims to combine the advantages of passive energy conservation and active regulation. Representative approaches include varying the stiffness by adjusting the amount of spring compression in a tandem spring drive with a motor (e.g., PANTOE prostheses) or varying the effective length of leaf springs by moving the fulcrum (e.g., variable stiffness humanoid feet designed by Choi et al, VSF prostheses designed by Glanzer). These approaches, while achieving stiffness adjustment, still suffer from deficiencies in the mechanical design. First, the metatarsophalangeal joints of the above-described solutions generally do not have active dorsiflexion and plantarflexion functions, or require additional joint drive motors to be implemented, resulting in an increased number of motors, and an increase in volume and weight. Secondly, the mechanism based on changing the effective length of the spring piece needs a longer spring piece and a rigid guide rail for moving a fulcrum, the structure is not compact and light, and the scheme based on the linear spring also has the problem of large occupation of longitudinal space. Given that the metatarsophalangeal joint is located at the extremity of the sole of the robot, which is extremely sensitive to size and weight, these drawbacks of the prior art severely limit its engineering application on foot-type robots. Disclosure of Invention Aiming at the problems in the prior art, the invention aims to provide the variable-rigidity metatarsophalangeal joint and foot type robot based on the combination of the torsion spring and the connecting rod, which can realize active dorsiflexion and plantar flexion movements of the metatarsophalangeal joint through a lightweight compact structure and has rigidity and angle adjusting capability. In order to achieve the above purpose, the invention adopts the following technical scheme: A variable stiffness metatarsophalangeal joint based on a torsional spring and connecting rod combination comprises a rear sole, a front sole, a metatarsophalangeal joint rotating shaft, a torsional spring, a connecting rod, a stay bar and a driving module; The front sole is rotationally connected with the rear sole through a rotating shaft of the metatarsophalangeal joint; one end of the stay bar is connected with the driving module, the other end is hinged with one end of the connecting rod, The spring coil of the torsion spring is sleeved on the rotating shaft of the