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

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

Technical Field

[0001] The invention relates to the technical field of electric wheelchair seat posture adjustment, and specifically to an electric wheelchair seat posture adjustment method and device based on muscle fatigue detection technology. Background Art

[0002] As an important rehabilitation aid, wheelchairs are widely used by individuals with limited mobility, especially the elderly and other people with lower limb mobility disorders. Although wheelchairs play an important role in improving the quality of life and social activities of these people, the health problems caused by sitting in wheelchairs for a long time also need to be paid attention to.

[0003] When people are in a sitting position, the waist muscle group plays a key role in supporting the spine and maintaining body stability, and is an important part of the human body's core muscle group. However, sitting in a wheelchair for a long time may cause continuous tension and fatigue in the waist muscles, which in turn causes discomfort in the waist. In addition, since the buttocks and thighs of the human body are in a relatively static state during the use of the wheelchair, some muscles are in a state of relaxation or contraction for a long time; the pressure of the body's weight restricts blood circulation, which can easily make the buttocks and leg muscles feel stiff and numb. This situation greatly affects the comfort and quality of life of wheelchair users. To address this problem, it is generally necessary to adjust the wheelchair seat posture with the assistance of nursing staff to relieve muscle fatigue, which mainly includes adjusting the wheelchair backrest, footrest and other parts, so that the occupant can change from a sitting position to a semi-recumbent position to relieve pressure on the waist, buttocks and legs. The current methods for adjusting the wheelchair seat posture include but are not limited to the following:

[0004] 1. The document "An electric wheelchair with full posture adjustment" (patent, application publication number: CN116158919A) provides an electric wheelchair with full posture adjustment, which can realize automatic adjustment of various postures such as sitting, standing, and lying. When in use, the extension and retraction of the electric push rod can be controlled according to the scheme set by the user or the program to achieve adjustment and fixation of any posture to meet the needs of the user, and the user can choose the most comfortable posture according to the characteristics of different users. The above method relies on the setting of the program during the control process, does not interact with the user, and cannot make corresponding adjustments to the wheelchair according to the user's real-time physical and physiological state.

[0005] 2. The document “Wheelchair Posture Adjustment Switching Mechanism, Wheelchair Posture Adjustment Switching Method and Wheelchair” (patent, application publication number: CN109620563A) invented a wheelchair posture adjustment switching mechanism, a wheelchair posture adjustment switching method and a wheelchair, which can quickly realize the sitting tilt angle of the wheelchair and the state switching adjustment between sitting, lying and standing positions through the telescopic stroke of two electric push rods. However, the above mechanism and device rely on the remote control to issue instructions to the controller and adjust the operating state of the push rod, that is, manual operation is required during control, which is not convenient for the elderly or some patients. Summary of the invention

[0006] To solve the above problems, the present invention discloses a method and device for adjusting the seat posture of an electric wheelchair based on muscle fatigue detection technology, that is, actively detecting the physiological information of the occupant to assist in controlling the actuator on the electric wheelchair to achieve autonomous adjustment of the seat posture.

[0007] 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 an actuator of the electric wheelchair respectively;

[0008] The main controller is used to obtain data information from the two modules and control the electric actuator on the wheelchair to achieve a fully autonomous wheelchair seat posture adjustment function;

[0009] The muscle fatigue detection module includes an electrode patch and a wire, a surface myoelectric signal preprocessing circuit, an MCU and a module power supply. The electrode patch and the wire are used to obtain the surface myoelectric signal of the human body. The surface myoelectric signal preprocessing circuit includes an instrument amplifier circuit, an active bandpass filter circuit and a co-phase adder circuit, which can perform preprocessing such as signal amplification and filtering on the original surface myoelectric signal, and then the MCU collects and further analyzes it.

[0010] The human posture sensing module is distributed in the backrest, seat cushion and footrest of the wheelchair. The module consists of a thin film pressure sensor, an acquisition card and an MCU. It can collect the pressure conditions of the three parts of the wheelchair and send them to the main controller. When it is detected that the human body has been adjusted to an appropriate posture, the adjustment action of the electric actuator is stopped, which plays a feedback role in the process of adjusting the wheelchair posture.

[0011] The electric wheelchair actuator for posture adjustment includes a backrest electric push rod, a leg support angle adjustment motor and a foot pedal electric push rod, and these actuators are controlled and operated by the main controller.

[0012] A method for adjusting the seat posture of an electric wheelchair based on muscle fatigue detection technology, the specific steps of which are:

[0013] 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;

[0014] S2. The built-in MCU of the muscle fatigue detection module performs windowing processing on the collected electromyographic signals, and calculates the mean power frequency (MPF) of the electromyographic signals in each fixed window respectively, and normalizes the MPF values ​​of the electromyographic signals from different parts (the second window and thereafter) by the initial MPF value (the first window), and uses the normalized MPF value as the discrimination index of muscle fatigue;

[0015] 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;

[0016] 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 is as follows:

[0017] 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;

[0018] 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;

[0019] S43. During the rotation and lifting process of the leg rest 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 (when the current pressure contact area of ​​the pedal is continuously less than 90% of the initial contact area), that is, the foot is suspended due to the low height of the pedal, the electric actuator (1430) will be 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 (when the current pressure contact area of ​​the seat cushion is continuously less than 90% of the initial contact area), that is, the leg is over-bent due to the high height of the pedal, and the thigh of the human body leaves the seat cushion, the electric actuator (1430) will be controlled to lower the pedal until the pressure contact area recovers to ±5% of the initial contact area. If the above two actions conflict, the pressure contact area of ​​the pedal will be prioritized.

[0020] S44. In summary, during the entire adjustment process, the pressure area at the footrest and the seat cushion needs to be kept unchanged, and the pressure area at 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.

[0021] 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.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. It can assist the user in adjusting the wheelchair seat posture by detecting the user's muscle fatigue status without manual instructions.

[0024] 2. At the same time, it can sense the user's body posture to determine whether it is in the desired resting posture, and stop the electric actuator of the wheelchair to achieve autonomous adjustment.

[0025] 3. During operation, the system can actively interact and obtain the user's physiological information, which solves the operational inconvenience of some users when using electric wheelchairs, improves the user experience in the process of using the wheelchair, and improves the human-machine collaboration of current electric wheelchairs.

[0026] 4. The present invention starts from the perspective of muscle fatigue detection and uses autonomous adjustment to better assist users in adjusting their seat posture, avoiding fatigue caused by maintaining the same sitting posture for a long time, thereby improving user comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the invention;

[0028] Figure 2 This is a schematic diagram of the muscle fatigue detection module structure;

[0029] Figure 3 This is a schematic diagram of the structure of the human posture perception module;

[0030] Figure 4 This is a schematic diagram of the location of the electric actuator of the wheelchair;

[0031] Figure 5 This is a schematic diagram of the installation position of the pressure sensor;

[0032] Figure 6 This is a schematic diagram of the running direction of each position of the wheelchair posture adjustment function. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present 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 accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0034] like Figure 1 The electric wheelchair seat posture adjustment device based on muscle fatigue detection technology of this embodiment includes 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 realize the fully autonomous wheelchair seat posture adjustment function. The main controller 110 is used to obtain data information of the two modules and control the electric actuator on the wheelchair to realize the fully autonomous wheelchair seat posture adjustment function.

[0035] like Figure 2As shown, the muscle fatigue detection module 120 includes electrode patches and wires 1210, an electromyographic signal preprocessing circuit 1220, an MCU 1230 and a module power supply 1240. The electrode patches and wires are used to obtain the electromyographic signal of the human body. The electromyographic signal preprocessing circuit includes an instrument amplifier circuit 1221, an active bandpass filter circuit 1222 and an in-phase adder circuit 1223, which can perform preprocessing such as signal amplification and filtering on the original electromyographic signal, and then the MCU collects and further analyzes it.

[0036] like Figure 3 As shown, the human posture sensing module 130 is distributed in three parts of the wheelchair: 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 1330. It can collect the pressure conditions of the three parts of the above-mentioned wheelchair and send them to the main controller. When it is detected that the human body has been adjusted to an appropriate posture, the adjustment action of the electric actuator is stopped, which plays a feedback role in the process of wheelchair posture adjustment.

[0037] like Figure 4-6 As shown, the electric wheelchair actuator 140 for posture adjustment includes a backrest electric push rod 1410, a leg support angle adjustment motor 1420 and a foot pedal electric push rod 1430, and these actuators are controlled and operated by the main controller.

[0038] A method for adjusting the seat posture of an electric wheelchair based on muscle fatigue detection technology, the specific steps of which are:

[0039] 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;

[0040] S2. The built-in MCU of the muscle fatigue detection module performs windowing processing on the collected electromyographic signals, and calculates the mean power frequency (MPF) of the electromyographic signals in each fixed window respectively, and normalizes the MPF values ​​of the electromyographic signals from different parts (the second window and thereafter) by the initial MPF value (the first window), and uses the normalized MPF value as the discrimination index of muscle fatigue;

[0041] 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;

[0042] 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 is as follows:

[0043] 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;

[0044] 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;

[0045] S43. During the leg rest rotation and lifting process in step S42, the two 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 foot is suspended due to the low height of the pedal, the electric actuator of the pedal needs to be controlled to raise the pedal. When the force area of ​​the pressure sensor at the seat cushion decreases, that is, the leg is over-bent due to the high height of the pedal (the thigh of the human body leaves the seat cushion), the electric actuator of the pedal needs to be controlled to lower the pedal.

[0046] S44. In summary, during the entire adjustment process, the pressure area at the footrest and the seat cushion needs to be kept unchanged, and the pressure area at 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.

[0047] 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.

[0048] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above technical features.

Claims

1. A method for adjusting the seat posture of an electric wheelchair based on muscle fatigue detection technology, characterized in that: The invention 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 realize 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; the electromyographic signal preprocessing circuit (1220) comprises an instrument amplifier circuit (1221), an active bandpass filter circuit (1222) and a synchronous 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); the pressure conditions of the three parts of the wheelchair are collected and 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, playing a feedback role in the process of wheelchair posture adjustment; the electric wheelchair actuator (140) for posture adjustment includes a backrest electric push rod (1410), a leg support angle adjustment motor (1420) and a footrest 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.

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