CN118044955B

CN118044955B - Electric wheelchair seat posture adjusting method and device based on muscle fatigue detection

Info

Publication number: CN118044955B
Application number: CN202410151047.1A
Authority: CN
Inventors: 崔建伟; 王远博; 黄子正; 余斯吉
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2024-02-02
Filing date: 2024-02-02
Publication date: 2024-12-17
Anticipated expiration: 2044-02-02
Also published as: CN118044955A

Abstract

The present invention provides an electric wheelchair seat posture adjustment device based on muscle fatigue detection, comprising an electric wheelchair, a human posture sensing module, a muscle fatigue detection module and a main controller, wherein the main controller is electrically connected to the muscle fatigue detection module, the human posture sensing module and the actuator of the electric wheelchair respectively; the main controller is used to obtain data information of the two modules and control the electric actuator on the wheelchair to realize a fully autonomous wheelchair seat posture adjustment function; the present invention actively detects the physiological information of the occupant to assist in controlling the actuator on the electric wheelchair to realize autonomous adjustment of the seat posture.

Description

Electric wheelchair seat posture adjusting method and device based on muscle fatigue detection

Technical Field

The invention relates to the technical field of electric wheelchair seat posture adjustment, in particular to an electric wheelchair seat posture adjustment method and device based on a muscle fatigue detection technology.

Background

The wheelchair is used as an important rehabilitation auxiliary tool and is widely applied to individuals with mobility impairment, especially the elderly and other people with lower limb mobility impairment. Although wheelchairs play an important role in improving the quality of life and social activity participation of these people, health problems caused by sitting on wheelchairs for a long period of time also need to be of interest.

When people are in sitting postures, the lumbar muscle group plays a key role in supporting the spine and maintaining posture stability, and is an important part of the human nuclear myocardial group. However, sitting on a wheelchair for a long time may cause continuous tension and fatigue of the waist muscles, thereby causing discomfort to the waist. In addition, as the buttocks, thighs and the like of a human body are in a relatively static state in the use process of the wheelchair, part of muscles are in a diastole or contraction state for a long time, and the blood circulation is limited due to the compression of the weight of the human body, the muscles at the hip and the leg of the human body are easy to feel stiff and numb, and the comfort and the quality of life of a wheelchair user are greatly influenced. In order to solve the problem, the posture of the wheelchair seat is generally required to be adjusted with the assistance of nursing staff to relieve the fatigue of muscles, wherein the adjustment of the back rest, the pedals and other parts of the wheelchair is mainly included, so that the sitting posture of an occupant is changed into a semi-prone posture to relieve the pressure of the waist, the buttocks and the legs. Current methods for wheelchair seat posture adjustment are, but not limited to, the following:

1. The literature 'an electric wheelchair with full posture adjustment' (patent application publication number: CN 116158919A) provides an electric wheelchair with full posture adjustment, which can realize automatic adjustment of various postures such as sitting posture, standing posture, lying posture and the like. When the electric push rod is used, the telescopic quantity of the electric push rod can be controlled according to a scheme set by a user or a program to realize adjustment and fixation of any gesture so as to meet the requirements of the user, and the user can select the most comfortable gesture according to the characteristics of different users. The method depends on program setting in the control process, does not interact with the user, and cannot correspondingly adjust the wheelchair according to the real-time physical and physiological state of the user.

2. The document "wheelchair posture adjustment and switching mechanism, wheelchair posture adjustment and switching method and wheelchair" (patent application publication number: CN 109620563A) invents a wheelchair posture adjustment and switching mechanism, wheelchair posture adjustment and switching method and wheelchair, and the sitting posture inclination angle of the wheelchair and the state switching adjustment among sitting posture, lying posture and standing posture can be rapidly realized through the telescopic travel of two electric push rods. However, the mechanism and the device rely on the remote controller to give an instruction to the controller and adjust the running state of the push rod, namely, the operation needs to be performed manually during the control, which is inconvenient for the old people or part of patients.

Disclosure of Invention

In order to solve the problems, the invention discloses a seat posture adjusting method and device of an electric wheelchair based on a muscle fatigue detection technology, namely, an executing mechanism on the electric wheelchair is controlled in an auxiliary mode through actively detecting physiological information of an occupant to realize automatic adjustment of the seat posture.

The seat posture adjusting device of the electric wheelchair based on muscle fatigue detection comprises an electric wheelchair, a human body posture sensing module, a muscle fatigue detection module and a main controller, wherein the main controller is respectively and electrically connected with the muscle fatigue detection module, the human body posture sensing module and an executing mechanism of the electric wheelchair;

The main controller is used for acquiring data information of the two modules and controlling an electric actuating mechanism on the wheelchair so as to realize a fully-autonomous wheelchair seat posture adjusting function;

the muscle fatigue detection module comprises an electrode patch and a lead, a surface electromyographic signal preprocessing circuit, an MCU (micro control unit) and a module power supply, wherein the electrode patch and the lead are used for acquiring the surface electromyographic signal of a human body, the surface electromyographic signal preprocessing circuit comprises an instrument amplifier circuit, an active band-pass filter circuit and an in-phase adder circuit, and can perform preprocessing such as signal amplification and filtering on the original surface electromyographic signal, and then the MC is used for acquiring and further analyzing;

The human body posture sensing module is distributed at three parts of a backrest, a cushion and a pedal of the wheelchair, and consists of a film pressure sensor, a collecting card and an MCU (micro control unit), can collect pressure conditions of the three parts of the wheelchair and send the pressure conditions to the main controller, and stops the regulating action of the electric executing mechanism when the condition that the human body is regulated to a proper posture is detected, so that a feedback effect is achieved in the posture regulating process of the wheelchair;

the electric wheelchair actuating mechanism for posture adjustment comprises a backrest electric push rod, a leg support angle adjusting motor and a pedal electric push rod, and the actuating mechanisms are controlled by the main controller to operate.

An electric wheelchair seat posture adjusting method based on a muscle fatigue detection technology comprises the following specific steps:

S1, when a user uses the wheelchair, the muscle fatigue detection module can acquire surface electromyographic signals of the waist and the legs of the human body in real time, and specific parts comprise the erector spinal muscle of the waist and the quadriceps femoris muscle of the legs;

S2, the MCU built in the muscle fatigue detection module performs windowing processing on the collected electromyographic signals, calculates average power frequencies (Mean Power Frequency, MPF) of the electromyographic signals in each fixed window, performs normalization processing on the MPF values (a second window and later) of the electromyographic signals from different parts divided by the initial MPF value (a first window), and uses the normalized MPF value as a judging index of muscle fatigue;

S3, when the average power frequency of the human waist and leg muscle groups detected in S2 is reduced, namely, when the fatigue condition of the human waist and leg muscle groups is identified, the main controller gives a control instruction to the electric executing mechanism, the wheelchair seat is gradually changed from a sitting posture to a semi-prone posture, and meanwhile, the muscle fatigue detection module enters a standby state;

S4, in the process of adjusting the wheelchair seat, the human body posture sensing module is used for detecting and feeding back the pressure distribution condition of a user on the wheelchair, and the specific adjusting method comprises the following steps:

S41, in the adjusting process, as the human body is gradually changed from sitting to prone, part of the weight of the human body is transferred to the backrest from the seat cushion, the stress area of the pressure sensor at the backrest is gradually increased, and the adjustment of the backrest angle is completed when the stress area gradually tends to be unchanged, and at the moment, the electric actuating mechanism at the backrest stops working;

S42, the leg support angle adjusting motor and the backrest electric executing mechanism in the step S41 have the same running time, namely the leg support angle adjusting motor is triggered to run together when the backrest is adjusted so as to keep a relative reasonable posture when the human body is divided by the backrest;

S43, in the process of rotating and lifting the leg rest in the step S42, a suspended or knee bending state of two feet possibly occurs due to the problem of the height of the pedals, at this time, whether an electric actuating mechanism at the pedal is adjusted or not is judged by detecting the conditions of the pressure sensors at the seat cushion and the pedal, specifically, when the pressure sensor stress area at the pedal is reduced (when the current pressure contact area of the pedal is continuously smaller than 90% of the initial contact area), namely, the condition that the feet are suspended due to the fact that the height of the pedals is too low, at this time, the electric actuating mechanism (1430) is controlled to lift the pedals until the contact area of the pressure is restored to +/-5% of the initial contact area, and when the pressure sensor stress area at the seat cushion is reduced (when the current pressure contact area of the seat cushion is continuously smaller than 90% of the initial contact area), namely, the leg is excessively bent due to the fact that the height of the pedals is too high, at this time, the electric actuating mechanism (1430) is controlled to be lowered until the contact area of the pressure is restored to +/-5% of the initial contact area, and if the two actions are in conflict, the contact area of the pressure at the pedal is preferentially ensured;

S44, integrating the steps, keeping the pressure areas of the pedals and the seat cushion unchanged in the whole adjusting process, and enabling the pressure area of the backrest to reach the maximum value, namely the expected semi-lying posture, wherein the posture adjusting action of the wheelchair is completed.

S5, after the posture of the wheelchair is adjusted, a user can decide when to end the rest state of the semi-prone position and resume the sitting position, when a reset instruction is received, the main controller drives the electric executing mechanism to resume the initial sitting state, and the muscle fatigue detection module resets and resumes operation.

Compared with the prior art, the invention has the beneficial effects that:

1. The wheelchair seat posture adjustment can be assisted by detecting the muscle fatigue state of the user, and a manual instruction is not required.

2. Meanwhile, the body posture of the user can be perceived to judge whether the wheelchair is in the expected rest posture or not, and the electric actuating mechanism of the wheelchair is stopped, so that the wheelchair can be adjusted autonomously.

3. In the running process, the system can actively interact and acquire physiological information of the user, solves the problems of inconvenient operation and the like of part of users in the process of using the electric wheelchair, improves the user experience in the process of using the wheelchair, and improves the man-machine cooperativity of the existing electric wheelchair.

4. The invention better assists the user to adjust the gesture of the seat in an autonomous adjustment mode from the aspect of muscle fatigue detection, avoids fatigue caused by keeping the same sitting posture for a long time, and further improves the comfort of the user.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the invention;

FIG. 2 is a schematic diagram of a muscular fatigue detection module structure;

FIG. 3 is a schematic diagram of a human posture sensing module;

FIG. 4 is a schematic illustration of the position of the wheelchair electric actuator;

FIG. 5 is a schematic diagram of a pressure sensor mounting location;

Fig. 6 is a schematic view of the direction of travel of the wheelchair posture adjustment function.

Detailed Description

The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "inner" and "outer" refer to directions toward or away from, respectively, the geometric center of a particular component.

As shown in fig. 1, the electric wheelchair seat posture adjustment device based on the muscle fatigue detection technology in this embodiment includes an electric wheelchair executing mechanism 140, a human body posture sensing module 130, a muscle fatigue detection module 120 and a main controller 110, wherein the main controller 110 is electrically connected with the muscle fatigue detection module 120, the human body posture sensing module 130 and the electric wheelchair executing mechanism 140, respectively, and the main controller 110 is configured to obtain the human body posture sensing module 130, the muscle fatigue detection module 120 and control the wheelchair electric executing mechanism 140, so as to implement a fully-autonomous wheelchair seat posture adjustment function. The main controller 110 is used for acquiring data information of the two modules and controlling an electric actuating mechanism on the wheelchair so as to realize a fully-autonomous wheelchair seat posture adjusting function.

As shown in fig. 2, the muscle fatigue detection module 120 includes an electrode patch and a lead 1210, a surface electromyographic signal preprocessing circuit 1220, a MCU-1230 and a module power source 1240, where the electrode patch and the lead are used to obtain a surface electromyographic signal of a human body, the surface electromyographic signal preprocessing circuit includes an instrumentation amplifier circuit 1221, an active band-pass filter circuit 1222 and an in-phase adder circuit 1223, and can perform signal amplification, filtering and other preprocessing on the original surface electromyographic signal, and then the signal is collected and further analyzed by the MCU.

As shown in fig. 3, the human body posture sensing module 130 is distributed on three parts of the backrest 1510, the cushion 1520 and the foot rest 1530 of the wheelchair, and is composed of a film pressure sensor 1310, a collection card 1320 and an MCU1330, and is capable of collecting pressure conditions of the three parts of the wheelchair and sending the pressure conditions to the main controller, and stopping the adjustment action of the electric actuator when detecting that the human body has been adjusted to a proper posture, so as to play a feedback role in the process of adjusting the posture of the wheelchair.

As shown in fig. 4-6, the electric wheelchair actuating mechanism 140 for posture adjustment includes a backrest electric push rod 1410, a leg rest angle adjusting motor 1420, and a foot electric push rod 1430, which are controlled to operate by the main controller.

S43, in the process of rotating and lifting the leg rest in the step S42, the two feet possibly have suspended or bent knee states due to the problem of the pedal height, at this time, whether the electric actuating mechanism at the pedal is adjusted or not is judged by detecting the conditions of the pressure sensors at the seat cushion and the pedal, specifically, when the stress area of the pressure sensor at the pedal is reduced, namely, the condition that the feet are suspended due to the fact that the pedal height is too low, the electric actuating mechanism of the pedal is required to be controlled to lift the pedal, and when the stress area of the pressure sensor at the seat cushion is reduced, namely, the condition that the legs are excessively bent due to the fact that the pedal height is too high (the thighs of a human body leave the seat cushion), at this time, the electric actuating mechanism of the pedal is required to be controlled to lower the pedal;

The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features.

Claims

1. A method for adjusting the seat posture of an electric wheelchair based on muscle fatigue detection technology, characterized in that it comprises an electric wheelchair actuator (140), a human posture sensing module (130), a muscle fatigue detection module (120) and a main controller (110), wherein the main controller (110) is electrically connected to the muscle fatigue detection module (120), the human posture sensing module (130) and the electric wheelchair actuator (140) respectively; the main controller (110) is used to obtain the human posture sensing module (130), the muscle fatigue detection module (120) and control the wheelchair electric actuator (140) to achieve a fully autonomous wheelchair seat posture adjustment function; the muscle fatigue detection module (120) comprises an electrode patch and a wire (1210), an electromyographic signal preprocessing circuit (1220), an MCU (1230) and a module power supply (1240), the electrode patch and the wire are used to obtain the electromyographic signal of the human body, and the electromyographic signal preprocessing circuit (1220) comprises an instrument amplifier circuit (1221) , an active bandpass filter circuit (1222) and an in-phase adder circuit (1223); amplifying and filtering the original electromyographic signal, and then collecting and further analyzing it by the MCU 1; the human posture sensing module (130) is distributed in three parts of the wheelchair, namely the backrest (1510), the seat cushion (1520) and the footrest (1530). The module is composed of a thin film pressure sensor (1310), an acquisition card (1320) and an MCU 2 (1330), which can collect the above-mentioned wheelchair The pressure conditions of the three parts are sent to the main controller (110); when it is detected that the human body has been adjusted to an appropriate posture, the adjustment action of the electric actuator is stopped, thereby playing a feedback role in the process of adjusting the wheelchair posture; the electric wheelchair actuator (140) for posture adjustment comprises a backrest electric push rod (1410), a leg support angle adjustment motor (1420) and a foot pedal electric push rod (1430), wherein the electric wheelchair actuator (140) is controlled and operated by the main controller (110);

The specific steps are:

S1. When the user uses a wheelchair, the muscle fatigue detection module can collect real-time electromyographic signals of the human waist and legs, including the erector spinae muscles of the waist and the quadriceps femoris of the legs;

S2. The MCU built into the muscle fatigue detection module performs windowing processing on the collected electromyographic signals, and calculates the average power frequency of the electromyographic signals in each fixed window respectively. The MPF values of the electromyographic signals from different parts of the second window and thereafter are normalized by dividing the initial MPF value of the first window, and the normalized MPF value is used as the discrimination index of muscle fatigue;

S3. When the average power frequency of the waist and leg muscles detected in S2 decreases, that is, when fatigue of the waist and leg muscles is detected, the main controller issues a control instruction to the electric actuator to gradually adjust the wheelchair seat from a sitting position to a semi-recumbent position, and the muscle fatigue detection module enters a standby state;

S4. During the process of adjusting the wheelchair seat, the human posture sensing module is used to detect and feedback the pressure distribution of the user on the wheelchair; the specific adjustment method steps of S4 are:

S41. During the adjustment process, as the human body gradually changes from a sitting position to a lying position, part of the human body's weight will be transferred from the seat cushion to the backrest, so the force-bearing area of the pressure sensor at the backrest will gradually increase. When the force-bearing area gradually tends to remain unchanged, the adjustment of the backrest angle is completed, and at this time, the electric actuator at the backrest stops working;

S42. The leg rest angle adjustment motor has the same running time as the backrest electric actuator in step S41, that is, the leg rest angle adjustment motor is triggered to run together with the backrest to maintain a relatively reasonable posture of the human body;

S43. During the leg rest rotation and lifting process in step S42, the feet may be suspended or bent due to the height of the pedal. At this time, the pressure sensors at the seat cushion and the pedal are detected to determine whether to adjust the electric actuator at the pedal. Specifically, when the force area of the pressure sensor at the pedal decreases, that is, the current pressure contact area of the pedal is continuously less than 90% of the initial contact area, the foot is suspended due to the low height of the pedal. At this time, the electric actuator (1430) is controlled to raise the pedal until the pressure contact area recovers to ±5% of the initial contact area. When the force area of the pressure sensor at the seat cushion decreases, the current pressure contact area of the seat cushion is continuously less than 90% of the initial contact area, that is, the leg is excessively bent due to the high height of the pedal, and the thigh of the human body leaves the seat cushion. At this time, the electric actuator (1430) is controlled to lower the pedal until the pressure contact area recovers to ±5% of the initial contact area. If there is a conflict between the pedal raising and pedal lowering actions, the pressure contact area of the pedal is prioritized.

S44. Combining the above steps, the pressure area of the footrest and the seat cushion needs to be kept unchanged during the entire adjustment process, and the pressure area of the backrest reaches the maximum value, which is the desired semi-recumbent posture. At this time, the posture adjustment action of the wheelchair is completed;

S5. After the posture adjustment of the wheelchair is completed, the user can decide when to end the semi-recumbent resting state and resume the sitting position. When receiving the reset instruction, the main controller drives the electric actuator to return to the initial sitting state, and the muscle fatigue detection module is reset and restarted.