Intelligent control method for ankle-foot walker

Abstract

An intelligent control method for an ankle-foot walker belongs to the technical field of ankle-foot walkers. The ankle-foot walker includes a walking mechanism and an electric push rod driving the walking mechanism. A group of plantar pressure sensors are provided on the walking mechanism. The plantar pressure sensors and the electric push rod are both connected to the external control system signal. The intelligent control method for the ankle-foot walker includes the following steps: S1, pressure value-voltage signal conversion; S2, ankle joint motion state identification; S3, electric push rod telescopic distance ΔL calculation; S4, electric push rod drives the ankle-foot walker to move. The present invention establishes a bionic exoskeleton model that fits the human body curve, uses a plantar pressure sensor to receive the plantar pressure signal of the healthy limb, and calculates the angle required for the affected limb to walk by judging the patient's gait. The affected limb of the patient is driven to move by the change in the length of the electric push rod to assist the patient in completing simple walking.

Description

Technical Field

[0001] The present invention belongs to the technical field of ankle-foot walkers, and in particular relates to an intelligent control method for an ankle-foot walker. Background Art

[0002] With the continuous development of science and technology, mechanical exoskeletons are increasingly being used in various industries. In the field of assisted walking, exoskeletons are increasingly being used to assist lower limb training for people with mobility difficulties because of their advantages such as freeing up manpower.

[0003] As people age, they often experience changes in their body functions, such as a decline in physical strength and motor nerve function, which makes the body less sensitive, leading to slow movements and physical incoordination. At present, most elderly people do have muscle weakness, difficulty walking, and are prone to falling, which have a significant adverse impact on their health and life.

[0004] Currently, most devices used to assist walking are crutches, canes, etc., which have little effect on truly improving the lower limb motor ability of the elderly, such as ankle joint strength, and do not take into account the user's personalized needs and the coordination of their own movements.

[0005] Therefore, there is an urgent need for a new type of intelligently controlled walker that can effectively assist users in walking and exercise their ankle movement ability. Summary of the invention

[0006] In view of the above problems existing in the prior art, the object of the present invention is to provide an intelligent control method for an ankle-foot walker which is comfortable, convenient for users to wear and use, and can effectively assist users in walking.

[0007] The present invention provides the following technical solution: an intelligent control method for an ankle-foot walker, the ankle-foot walker includes a walking mechanism and an electric push rod driving the walking mechanism, a group of plantar pressure sensors are provided on the walking mechanism, the plantar pressure sensors and the electric push rod are both connected to an external control system signal, the intelligent control method for the ankle-foot walker includes the following steps:

[0008] S1. Pressure value-voltage signal conversion: The pressure value of the sole of the foot is collected through the sole pressure sensor i=1,…n, n represents the number of plantar pressure sensors, and the pressure value Converted into the corresponding output voltage signal U i ;

[0009] S2. Ankle joint motion state recognition: The BP neural network algorithm is used to build an ankle joint motion state recognition model and output the plantar pressure value. Mapping relationship with ankle joint angle value;

[0010] S3, calculation of the telescopic distance ΔL of the electric push rod: the output voltage signal U obtained in step S1 is i Input the ankle joint motion state recognition model constructed in step S2 to obtain the corresponding ankle joint angle value, and convert it into the telescopic distance ΔL of the electric push rod;

[0011] S4. The electric push rod drives the ankle-foot walker to move: the external control system transmits a signal to the electric push rod through a predetermined program according to the extension and retraction distance of the electric push rod obtained in step S3, controls the electric push rod to stretch or contract accordingly, and drives the ankle-foot walker to move.

[0012] Furthermore, in step S1, the output voltage signal U i The calculation formula is as follows:

[0013]

[0014] In the formula, R AO-RES is the feedback resistor size, The plantar pressure value measured by the sensor.

[0015] Furthermore, in step S2, the plantar pressure value The mapping formula with the ankle joint angle value θ is as follows:

[0016]

[0017] Where θ is the output value, is the input value, w i is the weight parameter and e is the error function.

[0018] Furthermore, in step S4, the calculation formula of the telescopic distance ΔL is as follows:

[0019]

[0020] Among them, ΔL is the telescopic distance of the electric push rod, L0 is the original extension length of the electric push rod, L1 is the horizontal distance between the rotation fulcrum and the electric push rod, the rotation fulcrum is the connection point between the calf support exoskeleton and the base plate, and θ is the ankle joint angle value.

[0021] Furthermore, the walking mechanism includes a calf mechanism and a plantar mechanism, the calf mechanism includes a calf support exoskeleton, and the plantar mechanism includes a base plate; the calf support exoskeleton and the base plate are hingedly connected, the calf support exoskeleton and the base of the electric push rod are hingedly connected, and the base plate and the push rod on the electric push rod are hingedly connected.

[0022] Furthermore, a calf strap assembly hole is provided at the upper portion of the calf support exoskeleton, a calf outer sheath matching the calf curve of a human body is provided at the middle portion, and an electric push rod base assembly hole is provided at the outer side of the calf outer sheath.

[0023] Furthermore, a calf support lining is fixedly installed on the inner side of the calf outer sleeve, and the shape of the calf support lining matches the shape of the calf outer sleeve.

[0024] Furthermore, an ankle support is provided on the bottom plate, and an electric push rod end assembly hole and a foot strap assembly hole are provided on the ankle support.

[0025] Furthermore, a flexible pad is provided on the upper part of the bottom plate, a group of plantar pressure sensors are arranged on the flexible pad, and an anti-slip pad is provided on the lower part of the bottom plate.

[0026] Furthermore, the plantar pressure sensor is arranged on the flexible pad at positions corresponding to the forefoot and the heel of the foot, and the plantar pressure sensor is connected to an external power supply via a wire.

[0027] Furthermore, the calf support exoskeleton, calf support lining and bottom plate are all manufactured by 3D printing.

[0028] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1) In the present invention, a bionic exoskeleton model that fits the human body curve is established, a plantar pressure sensor is used to receive the plantar pressure signal of the healthy limb, and the gait of the patient is judged to calculate the angle required for the affected limb to walk. The length of the electric push rod is changed to drive the patient's affected limb to move, so as to assist the patient to complete simple walking;

[0030] 2) The invention has a simple structure, is easy to wear and use, has good practicality, and can effectively assist the user in walking and exercise the athletic ability of the ankle;

[0031] 3) In the present invention, the flexible pad and the anti-slip pad are provided to further improve the comfort and safety of wearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the three-dimensional structure of an ankle-foot walker in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of a calf support exoskeleton in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a calf support lining in an embodiment of the present invention;

[0035] Figure 4This is a schematic diagram of the structure of an electric push rod in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of the bottom plate in an embodiment of the present invention;

[0037] Figure 6 It is a schematic diagram of the side structure of an ankle-foot walker in an embodiment of the present invention;

[0038] Figure 7 It is a front view structural schematic diagram of an ankle-foot walker in an embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the structure of the ankle-foot walker in motion state in an embodiment of the present invention;

[0040] Fig. 9 A distribution diagram of the plantar pressure sensor on the flexible pad in an embodiment of the present invention;

[0041] Fig.10 4 is a diagram showing the corresponding relationship between pressure value and ankle joint angle value in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments of the specification. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. Those skilled in the art can fully understand the present invention without the description of these details.

[0044] Example:

[0045] See also Figure 1-10 A novel ankle-foot walker comprises a walking mechanism and an electric push rod driving the walking mechanism.

[0046] Specifically, the walking mechanism includes a calf mechanism and a plantar mechanism; the calf mechanism includes a calf support exoskeleton 1, and a calf support lining 2 is installed on the inner side of the calf support exoskeleton 1; the plantar mechanism includes a base plate 4, and the calf support exoskeleton 1 and the base plate 4 are hingedly connected.

[0047] Specifically, the calf support exoskeleton 1 is hingedly connected to the base plate 4 , the base 3 on the electric push rod is hingedly set on the calf support exoskeleton 1 , and the push rod 5 of the electric push rod is hingedly connected to the base plate 4 .

[0048] Specifically, the calf support exoskeleton 1, such as Figure 2 As shown: it includes a calf outer cover 1.1, the shape of which fits the curve of the human calf and can be worn on the calf, and there are strip-shaped calf strap assembly holes 1.2 on both sides, two on each side; the strap passes through the calf strap assembly holes 1.2 to achieve wearing; a pair of electric push rod base assembly holes 1.3 are provided on the outside of the calf outer cover 1.1, which can be hinged to the base 3 of the electric push rod; self-tapping screw holes 1.4 are provided on the calf outer cover 1.1, 3 on each side and 2 in the middle vertical row, which can be fixedly connected to the calf support lining 2 by self-tapping screws; a connecting rod 1.5 is provided at the lower part of the calf outer cover 1.1, and the connecting rod 1.5 is hingedly connected to the sole mechanism.

[0049] Specifically, the calf support lining 2, such as Figure 3 As shown: it includes a calf lining body 2.1, whose shape fits the calf curve of the human body, and the calf lining body 2.1 is connected to the calf outer sheath 1.1 by self-tapping screws.

[0050] Specifically, Figure 4 As shown: the push rod 5 is nested in the base 3; the end of the push rod 5 located on one side of the base is connected to the calf outer sheath 1.1 through bolts; the push rod 5 and the base plate 4 are hingedly connected.

[0051] Specifically, the bottom plate 4, such as Figure 5 As shown: the ankle support 4.1 is in a U-shaped structure, with an electric push rod end assembly hole 4.2 on the outside, and the ankle support 4.1 is hinged with a bolt hole 5.2 on the 75mm electric push rod through the electric push rod end assembly hole 4.2 by bolts and nuts; pin holes 4.3 and strip-shaped foot strap assembly holes 4.4 are provided on both sides of the ankle support 4.1.

[0052] Among them, the calf support exoskeleton 1, the electric push rod 2 and the base plate 4 are all made by 3D printing.

[0053] This embodiment establishes a bionic exoskeleton model that fits the human body curve, uses a plantar pressure sensor to receive the plantar pressure signal of the healthy limb, and judges the patient's gait to calculate the angle required for the affected limb to walk. The length of the micro electric push rod is changed to drive the patient's affected limb to move, so as to assist the patient in completing simple walking.

[0054] The specific steps of the control process are described in detail as follows:

[0055] 1) Pressure value-voltage signal conversion: refer to Figure 7 In this example, a group of (3 in total) plantar pressure sensors A, B and C are used to measure the pressure values ​​of the forefoot and heel during walking.

[0056] The output voltage value of the linear voltage conversion module of the plantar pressure sensor is U i , voltage value U i Plantar pressure satisfy:

[0057]

[0058] In the formula, R AO-RES is the feedback resistor size, is the plantar pressure value measured by the sensor;

[0059] 2) Ankle joint motion state recognition: The BP neural network algorithm is used to build an ankle joint motion state recognition model. The input of the model is the pressure value of the three pressure sensors on the healthy side of the foot, and the output is the ankle joint angle value on the affected side. After the model is trained, the corresponding ankle joint angle can be output according to the real-time plantar pressure value.

[0060] Plantar pressure value The mapping relationship between the ankle joint angle value θ is as follows Fig.10 As shown, the output value can be obtained according to the following formula:

[0061]

[0062] Where θ is the output value, is the input value, w i is the weight parameter, all weights are initialized using a normal distribution with a mean of 0 and a variance of 1, and e is the error function. After obtaining the ankle joint angle, it can be converted into the telescopic distance of the push rod using the following formula:

[0063]

[0064] Among them, ΔL is the telescopic distance of the electric push rod, L0 is the original extension length of the electric push rod, L1 is the horizontal distance between the rotation fulcrum and the push rod, and θ is the ankle joint angle value.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent control method for an ankle-foot walker, characterized in that: The ankle-foot walker comprises a walking mechanism and an electric push rod driving the walking mechanism. A group of plantar pressure sensors are arranged on the walking mechanism. The plantar pressure sensors and the electric push rod are both connected to an external control system signal. The walking mechanism comprises a calf mechanism and a plantar mechanism. The calf mechanism comprises a calf support exoskeleton (1), and the plantar mechanism comprises a bottom plate (4). The calf support exoskeleton (1) and the bottom plate (4) are hingedly connected. The calf support exoskeleton (1) and a base (3) of the electric push rod are hingedly connected. The bottom plate (4) and a push rod (5) on the electric push rod are hingedly connected. The intelligent control method of the ankle-foot walker comprises the following steps: S1. Pressure value-voltage signal conversion: The pressure value of the sole of the foot is collected through the sole pressure sensor , i=1,…n, n represents the number of plantar pressure sensors, and the pressure value Converted into the corresponding output voltage signal ; The output voltage signal The calculation formula is as follows: ； In the formula, is the feedback resistor size, is the plantar pressure value measured by the sensor; S2. Ankle joint motion state recognition: Ankle joint motion state recognition is constructed using BP neural network algorithm State recognition model, build output plantar pressure value The mapping relationship between the ankle joint angle value and the plantar pressure value Ankle joint angle The mapping formula is as follows: ； in is the output value, is the input value, is the weight parameter, is the error function; S3. Telescopic distance of electric push rod Calculation: Substitute the output voltage signal obtained in step S1 Input the ankle joint motion state recognition model constructed in step S2 to obtain the corresponding ankle joint angle value, and convert it into the telescopic distance of the electric push rod The telescopic distance The calculation formula is as follows: ； in, is the telescopic distance of the electric push rod, is the original extension length of the electric push rod, is the horizontal distance between the rotation fulcrum and the electric push rod, the rotation fulcrum being the connection point between the calf support exoskeleton (1) and the base plate (4). is the ankle joint angle value; S4. The electric push rod drives the ankle-foot walker to move: the external control system transmits a signal to the electric push rod through a predetermined program according to the extension and retraction distance of the electric push rod obtained in step S3, controls the electric push rod to stretch or contract accordingly, and drives the ankle-foot walker to move.

2. The intelligent control method of an ankle-foot walker according to claim 1, characterized in that The upper part of the calf support exoskeleton (1) is provided with a calf strap assembly hole (1.2), the middle part is provided with a calf outer sleeve (1.1) matching the calf curve of a human body, and the outer side of the calf outer sleeve (1.1) is provided with an electric push rod base assembly hole (1.3).

3. The intelligent control method of an ankle-foot walker according to claim 2, characterized in that A calf support lining (2) is fixedly mounted on the inner side of the calf outer sleeve (1.1), and the shape of the calf support lining (2) matches the shape of the calf outer sleeve (1.1).

4. The intelligent control method for an ankle-foot walker according to claim 1 or 3, characterized in that An ankle support member (4.1) is provided on the bottom plate (4), and an electric push rod end assembly hole (4.2) and a foot strap assembly hole (4.4) are provided on the ankle support member (4.1).

5. The intelligent control method of an ankle-foot walker according to claim 4, characterized in that A flexible pad is provided on the upper part of the bottom plate (4), a group of foot pressure sensors are arranged on the flexible pad, and an anti-slip pad is provided on the lower part of the bottom plate (4).

6. The intelligent control method of an ankle-foot walker according to claim 5, characterized in that The plantar pressure sensor is arranged on the flexible pad at positions corresponding to the forefoot and the heel of the foot, and the plantar pressure sensor is connected to an external power source through a wire.

7. The intelligent control method of an ankle-foot walker according to claim 6, characterized in that The calf support exoskeleton (1), the calf support lining (2) and the bottom plate (4) are all manufactured by 3D printing.

Images