Sole exoskeleton capable of changing walking gravity center track

Abstract

A sole exoskeleton capable of changing a walking gravity center track belongs to the technical field of robots and comprises a bottom plate, a driving mechanism, a vertical elastic guide mechanism and a sole contact plate. The foot bottom contact plate is arranged above the bottom plate, two sets of driving mechanisms are arranged on the front portion and the rear portion of the bottom plate in the length direction of the foot respectively, the four sets of driving mechanisms are arranged in an array mode, the left portion and the right portion of the bottom plate are each provided with a set of vertical elastic guide mechanism, and the two sets of vertical elastic guide mechanisms are connected through a rotating shaft. The rotating shaft is rotatably arranged on the plate surface of the plantar contact plate, and the four sets of driving mechanisms synchronously work to realize rotation of the plantar contact plate relative to the rotating shaft and vertical movement of the plantar contact plate relative to the bottom plate. The up-and-down fluctuation amplitude of the gravity center in the human walking process can be reduced, so that the power assisting position is equivalent to the gravity center, energy metabolism consumption of the whole body is reduced, and walking efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a foot wearable device, in particular to a foot exoskeleton for changing the trajectory of the walking center of gravity, and belongs to the technical field of wearable robots. Background Art

[0002] As people's requirements for comfort and convenience in life continue to increase, walking-assisting exoskeletons have received widespread attention. The technical research of exoskeleton robots covers many aspects, among which the research on the power-assisting position is one of the keys. In the process of walking, maintaining the balance and stability of the center of gravity is of utmost importance. In a stable gait cycle, the center of gravity will fluctuate up and down in the sagittal plane with a fluctuation range of about 5-8cm. At this time, most of the energy will be consumed to balance the fluctuation of the center of gravity. The maximum work required to overcome gravity accounts for about 65% of the total energy.

[0003] Traditional walking-assisting exoskeletons usually assist at the hip, knee, ankle joints, etc., but few designs consider assisting at the center of gravity of the human body. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to propose a plantar exoskeleton that changes the trajectory of the center of gravity while walking. The plantar exoskeleton can reduce the up and down fluctuation amplitude of the center of gravity during human walking, so that the power assisting position is equivalent to the center of gravity, thereby reducing the whole body's energy metabolism consumption and improving walking efficiency.

[0005] A plantar exoskeleton for changing the trajectory of walking center of gravity comprises a base plate, a driving mechanism, a vertical elastic guiding mechanism and a plantar contact plate;

[0006] The sole contact plate is arranged above the base plate. Along the length direction of the foot, two sets of driving mechanisms are arranged at the front and rear parts of the base plate respectively. The four sets of driving mechanisms are arranged in an array. The left and right parts of the base plate are respectively provided with a set of vertical elastic guide mechanisms. The two sets of vertical elastic guide mechanisms are connected by a rotating shaft. The rotating shaft is rotatably arranged on the board surface of the sole contact plate. The four sets of driving mechanisms work synchronously to realize the rotation of the sole contact plate relative to the rotating shaft and the vertical movement relative to the base plate.

[0007] Furthermore, each set of the driving mechanism includes a servo, an output rod and a driven rod; the servo is installed on the base plate, the output end of the servo is connected to one end of the output rod, the other end of the output rod is rotatably connected to one end of the driven rod, and the other end of the driven rod is rotatably arranged on the surface of the sole contact plate.

[0008] Furthermore, each set of the vertical elastic guide mechanism includes a guide shaft, an oil-free bushing and a spring; the lower end of the guide shaft is installed on the base plate, and an oil-free bushing is provided on the guide shaft. The guide shaft can slide on the oil-free bushing, and the two oil-free bushings are connected by a rotating shaft. A spring is sleeved on the guide shaft, and the two ends of the spring are respectively against the oil-free bushing and the base plate.

[0009] The beneficial effects of the present invention compared with the prior art are as follows:

[0010] 1. This application proposes a new type of walking-assisting exoskeleton. The plantar exoskeleton changes the trajectory of the center of gravity to make the assisting position equivalent to the center of gravity of the human body.

[0011] 2. The exoskeleton uses parallel servo active control and high-strength compression spring passive balance to accurately control the height of the left and right soles, change the longitudinal height of the human body's center of gravity, and reduce the amplitude of center of gravity fluctuation. At the same time, the torque actively applied by the servo acts on the soles of the feet to assist the human body in walking. This reduces energy metabolism consumption during walking and improves walking efficiency.

[0012] The present application scheme is further described below with reference to the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A three-dimensional diagram of a plantar exoskeleton for changing the trajectory of the center of gravity when walking according to the present application;

[0014] Figure 2 It is a schematic diagram of the specific structure of the driving mechanism and the vertical elastic guiding mechanism;

[0015] Figure 3 This is a partial schematic diagram after removing the base plate and servo for this application. DETAILED DESCRIPTION

[0016] The embodiments of the technical solution of the present application are described in detail below in conjunction with the accompanying drawings. Unless otherwise specified, the technical terms or scientific terms used in the present application are generally understood by those skilled in the art.

[0017] The study of the power assist position of the exoskeleton robot is one of the key factors affecting balance stability. During walking, in a stable gait cycle, the center of gravity will fluctuate up and down in the sagittal plane. At this time, most of the energy will be consumed to balance the fluctuation of the center of gravity, and a large amount of work is required to overcome gravity.

[0018] In view of this, the present application provides a plantar exoskeleton for changing the trajectory of the center of gravity of walking, referring to Figure 1 , which comprises a base plate 1, a driving mechanism 2, a vertical elastic guiding mechanism 3 and a sole contact plate 4;

[0019] The sole contact plate 4 is arranged above the base plate 1. Along the length direction of the foot, two sets of driving mechanisms 2 are arranged at the front and rear parts of the base plate 1 respectively. The four sets of driving mechanisms 2 are arranged in an array, for example, two sets of driving mechanisms 2 are arranged in parallel at the front part, and two sets of driving mechanisms 2 are arranged in parallel at the rear part. A set of vertical elastic guide mechanism 3 is respectively arranged at the left and right parts of the base plate 1. The two sets of vertical elastic guide mechanisms 3 are connected by a rotating shaft 5, and the rotating shaft 5 is rotatably arranged on the board surface of the sole contact plate 4. The four sets of driving mechanisms 2 work synchronously to realize the rotation of the sole contact plate 4 relative to the rotating shaft 5 and the vertical movement relative to the base plate 1.

[0020] This embodiment adopts the active control of the driving mechanism and the passive balance of the vertical elastic guide mechanism, which can accurately control the height of the left and right soles, change the longitudinal height of the center of gravity of the human body, and reduce the fluctuation amplitude of the center of gravity during walking.

[0021] Optionally, refer to Figure 1 and Figure 2 Each set of the driving mechanism 2 comprises a steering gear 21, an output rod 22 and a driven rod 23;

[0022] The servo motor 21 is mounted on the bottom plate 1, the output end of the servo motor 21 is connected to one end of the output rod 22, the other end of the output rod 22 is rotatably connected to one end of the driven rod 23, and the other end of the driven rod 23 is rotatably arranged on the surface of the sole contact plate 4. Each set of the vertical elastic guide mechanism 3 comprises a guide shaft 31, an oil-free bushing 32 and a spring 33; the lower end of the guide shaft 31 is mounted on the bottom plate 1, and an oil-free bushing 32 is arranged on the guide shaft 31, and the guide shaft 31 can slide on the oil-free bushing 32, and the two oil-free bushings 32 are connected by a rotating shaft 5, and a spring 33 is sleeved on the guide shaft 31, and the two ends of the spring 33 are respectively against the oil-free bushing 32 and the bottom plate 1.

[0023] The four holes 41 are used for fixing the straps. After the human body wears the plantar exoskeleton, the foot is fixed by the straps at the holes. The servo will actively adjust the height of the left and right soles according to the gait, thereby reducing the longitudinal fluctuation amplitude of the center of gravity, changing the trajectory of the center of gravity, and providing positive torque to the sole of the foot to assist walking, thereby reducing the energy metabolism consumption of the human body.

[0024] This embodiment designs a bilaterally symmetrical mechanical structure consisting of a five-link mechanism and a guide shaft, which can realize the overall two degrees of freedom. The output shaft of the servo controls the rotation of the two connecting rods, and the two follower rods 23 and the sole contact plate 4 are three follower parts. This five-link mechanism cooperates with the constraint of the fixed ground to realize two degrees of freedom of movement and one degree of freedom of rotation of the sole contact plate 4 in the sagittal plane. For this purpose, a longitudinally arranged guide shaft 31 is added, and the guide shaft 31 is connected to the sole contact plate 4 through a rotating shaft 5 and a rotating pair (such as a bearing 6). The guide shaft 31 is fixed to the base plate 1 through a sleeve 34, and the guide shaft 31 is installed on the sleeve 34, and the sleeve 34 is installed on the base plate 1. This design can eliminate the degree of freedom of movement along the x-axis. A moving pair, i.e., an oil-free bushing 32, is added between the guide shaft 31 and the sole contact plate 4 to ensure longitudinal movement, thereby forming a two-degree-of-freedom device, i.e., movement along the z-axis and rotation around the y-axis. The plantar exoskeleton is fixed to the sole of the foot by toothed straps and safety buckles, ensuring comfort while saving time in putting on and taking off.

[0025] The control method of the plantar exoskeleton adopts a state machine model, and the motion of the device is converted into several discrete states according to the human gait law. The distributed IMU is used to detect the human posture. When the gait meets different conditions, the motion state of the steering gear 21 is different. When the IMU detects that the sole is in the support phase state, the pitch angle is 0, the sole is parallel to the ground, and the longitudinal height is the lowest. When the moment when the sole is detected to transition from the support phase to the swing phase, the longitudinal height rises to the highest point, and the upper plane of the plantar exoskeleton rotates positively before the sole, providing a positive torque for the sole, thereby reducing the energy consumption of the ankle joint and the calf muscle. When the sole is in the swing phase state, the pitch angle is always equal to the sole motion angle in the y-axis, and the longitudinal height decreases with the increase of the swing amplitude of the legs. Using this state machine algorithm, the plantar exoskeleton of this embodiment is controlled to change the height of the left and right soles, thereby changing the trajectory of the center of gravity of the human body and reducing the fluctuation amplitude of the center of gravity.

[0026] Furthermore, the base plate 1 is made of carbon fiber. The sole contact plate 4 is made of carbon fiber. The guide shaft 31 is made of carbon fiber. The output rod 22 and the driven rod 23 are made of aluminum alloy, which is light in weight, high in strength and good in toughness. Four parallel servos and two high-strength springs are used. The sole exoskeleton made of the above materials weighs about 0.95kg, and the weight of the whole set including the electrical system can be about 2.76kg (including 0.565kg of battery), which is comfortable and convenient to wear.

[0027] Working principle: Four servos 21 are fixed to the base plate 1, the output rod 22 and the driven rod 23 are assembled together through bearings, and are rotatably connected to the boss 7 arranged on the sole contact plate 4, the guide shaft 31 and the sleeve 34 are fixed by four screws, and the sleeve 34 is fixed to the base plate 1. The guide shaft 31 can slide freely in the oil-free bushing 32, and the two oil-free bushings 32 are fixed together by a rotating shaft 5. The rotating shaft 5 is assembled with the sole contact plate 4 through two bearings 6, so that the oil-free bushing 32 can rotate freely on both sides of the sole contact plate 4. The spring 33 (such as a compression spring) is fixed between the base plate 1 and the oil-free bushing 32, and the upper and lower planes are provided with grooves. When walking, most of the sole force is borne by the high-strength spring 33, and the elastic coefficient can be calculated according to the following formula:

[0028]

[0029] Where n t ——Number of servos, 4 in total;

[0030] l1——the length of the output rod 22;

[0031] α——the angle between the output rod 22 and the ground;

[0032] n k ——Number of springs, 2 in total;

[0033] Δh——Spring compression, unit: mm.

[0034] To meet the needs of users with a weight range of 68-80kg, the selected spring coefficient is 4.25N / mm. The spring is easy to disassemble, so the spring model can be replaced according to actual conditions to improve walking comfort.

[0035] The present application has been disclosed as above with preferred implementation cases, but it is not intended to limit the present application. Any technician familiar with the profession can make slight changes or modifications to the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present application, and the equivalent implementation cases with equivalent changes are still within the scope of the technical solution of the present application.

Claims

1. A plantar exoskeleton for changing the trajectory of the center of gravity while walking, characterized in that: It comprises a base plate (1), a driving mechanism (2), a vertical elastic guiding mechanism (3) and a sole contact plate (4); The sole contact plate (4) is arranged above the bottom plate (1). Along the length direction of the foot, two sets of driving mechanisms (2) are arranged at the front and rear parts of the bottom plate (1), respectively. The four sets of driving mechanisms (2) are arranged in an array. The left and right parts of the bottom plate (1) are respectively provided with a set of vertical elastic guide mechanisms (3). The two sets of vertical elastic guide mechanisms (3) are connected via a rotating shaft (5). The rotating shaft (5) is rotatably arranged on the plate surface of the sole contact plate (4). The four sets of driving mechanisms (2) work synchronously to realize the rotation of the sole contact plate (4) relative to the rotating shaft (5) and the vertical movement relative to the bottom plate (1).

2. A plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 1, characterized in that: Each set of the driving mechanism (2) comprises a steering gear (21), an output rod (22) and a driven rod (23); The steering gear (21) is mounted on the bottom plate (1), the output end of the steering gear (21) is connected to one end of an output rod (22), the other end of the output rod (22) is rotatably connected to one end of a driven rod (23), and the other end of the driven rod (23) is rotatably arranged on the surface of the sole contact plate (4).

3. The plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 1, characterized in that: Each set of the vertical elastic guide mechanism (3) comprises a guide shaft (31), an oil-free bushing (32) and a spring (33); The lower end of the guide shaft (31) is mounted on the bottom plate (1), an oil-free bushing (32) is arranged on the guide shaft (31), the guide shaft (31) can slide on the oil-free bushing (32), the two oil-free bushings (32) are connected by a rotating shaft (5), a spring (33) is sleeved on the guide shaft (31), and two ends of the spring (33) are respectively against the oil-free bushing (32) and the bottom plate (1).

4. The plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 1, characterized in that: The base plate (1) is made of carbon fiber.

5. The plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 1, characterized in that: The material of the sole contact plate (4) is carbon fiber.

6. The plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 2, characterized in that: The output rod (22) and the driven rod (23) are made of aluminum alloy.

7. The plantar exoskeleton for changing the trajectory of walking center of gravity according to claim 3, characterized in that: The guide shaft (31) is made of carbon fiber.

8. The plantar exoskeleton for changing the trajectory of the center of gravity when walking according to claim 3, characterized in that: The spring (33) is a compression spring.

9. The plantar exoskeleton for changing the trajectory of the center of gravity while walking according to claim 3, characterized in that: The guide shaft (31) is mounted on the sleeve (34), and the sleeve (34) is mounted on the base plate (1).

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