A wheelchair control method based on electrical impedance technology combined with tactile perception

Abstract

The present invention discloses a wheelchair control method based on electrical impedance technology combined with tactile perception, and the steps include: 1. N electrodes are evenly attached to the boundaries of flexible piezoresistive materials; 2. The acquisition device acquires voltage signals and transmits them to the host computer, and uses the TK-NOSER imaging method to perform two-dimensional imaging of the impedance distribution changes in the flexible piezoresistive material, and further calculates the coordinates of the touch position after threshold segmentation; 3. Six areas are divided on the flexible piezoresistive material for defining command operations; the area where the coordinates of the touch position fall is determined, thereby determining the wheelchair command; 4. The host computer sends the wheelchair command to the wheelchair controller to drive the wheelchair to perform the corresponding action. The present invention can quickly detect the signals corresponding to different touch commands and quickly control the wheelchair, thereby solving the problems of cumbersome wheelchair control operation, low sensitivity, difficult control, and high cost in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of electric wheelchair control, and specifically to a method for controlling a wheelchair based on electrical impedance technology combined with tactile perception. Background Art

[0002] As a device to assist rehabilitation therapy, electric wheelchairs are essential means of transportation for people with physical disabilities and mobility impairments. With the advancement of science and technology, especially the rapid development of human-computer interaction, it has become an important research direction to control the movement of wheelchairs through natural human living habits such as voice and body language to replace traditional human-computer interfaces such as buttons and joysticks. At present, common methods of controlling wheelchairs based on brain waves, electromyography, machine vision, and eye signals are used. For brain wave and electromyography control, the signals are relatively weak and easily interfered with, and brain waves require the user to concentrate highly at all times; machine vision is affected by the camera and limits the use space; the recognition of eye signals is highly interfered and long-term use will cause eye fatigue. In addition, a common disadvantage of the above control methods is high cost and poor stability. Summary of the invention

[0003] The present invention aims to solve the deficiencies of the above-mentioned prior art and provide a wheelchair control method based on electrical impedance technology combined with tactile perception, so as to quickly detect the signals corresponding to different touch commands and quickly control the wheelchair, thereby solving the problems of cumbersome wheelchair control operation, low sensitivity, difficult control and high cost in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The wheelchair control method based on electrical impedance technology combined with tactile perception of the present invention is characterized in that it is applied to a control system composed of a wheelchair controller, a signal acquisition device and a host computer, and includes the following steps:

[0006] Step 1, designing the signal acquisition device, including: an impedance chip, an analog switch, a single-chip microcomputer, a power module, electrodes and a flexible piezoresistive material;

[0007] N electrodes are attached to the flexible piezoresistive material and are evenly distributed at the boundaries of the flexible piezoresistive material. The analog switch is used to control the conduction and disconnection between the impedance chip and the electrodes. The impedance chip is used to output the detected excitation signal to the flexible piezoresistive material and collect the voltage signal measured by the electrode. The single-chip microcomputer is used to control the analog switch and process the voltage signal collected by the impedance chip. The power module is used to power the impedance chip, the analog switch, and the single-chip microcomputer.

[0008] When there is no touch action on the flexible piezoresistive material, the voltage data between any two different electrodes among the N electrodes are measured in sequence, thereby obtaining The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is no touch action;

[0009] When a touch action is performed on the flexible piezoresistive material, the voltage data between any two different electrodes among the N electrodes are not measured in sequence, so as to obtain The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is a touch action;

[0010] Step 2: The host computer uses the TK-NOSER imaging method to perform two-dimensional imaging of the impedance distribution change in the flexible piezoresistive material;

[0011] Step 2.1: Use the open source software package Eidors to establish a finite element model of the flexible piezoresistive material and obtain the number of electrodes N of the finite element model. elec and the number of units M elem ; Let M elem The conductivity of the unit is Among them, σ m Denotes the conductivity of the mth unit, let V ij (σ) is the voltage between the i-th model electrode and the j-th model electrode under the conductivity distribution of σ; m=1,2,...,M elem ,i,j=1,2,...,N elec ;

[0012] Step 2.2: Calculate the sensitivity matrix J of the finite element model using formula (1):

[0013]

[0014] Step 2.3: Calculate the voltage difference data of the touch action ΔV = V 1 -V 0 ;

[0015] Step 2.4: Calculate the conductivity change Δσ of the flexible piezoresistive material corresponding to the finite element model unit using formula (2):

[0016] Δσ=(J T WJ+λ 2 R) -1 J T WΔV=RM·ΔV (2)

[0017] In formula (2), λ represents the hyperparameter, R represents the prior matrix obtained by NOSER prior, and W is the unit matrix;

[0018] Step 2.5, generating an M×M conductivity distribution image P according to the conductivity change Δσ;

[0019] Step 2.6: Perform threshold segmentation on the conductivity distribution image P to obtain the segmented binary image P b , where P b The pixel value of the rth row and cth column in is obtained using formula (3):

[0020]

[0021] In formula (3), P(r,c) represents the pixel value of the rth row and cth column in the conductivity distribution image P, and t represents the threshold used for segmentation;

[0022] Step 2.7: Use formula (4) to calculate the segmented binary image P b The geometric center coordinates (x centre ,y centre ), and as touch coordinates:

[0023]

[0024] In formula (4), [P b ] pi Represents image P b The conductivity value at the pith pixel, x′ pi Represents image P b The horizontal coordinate value of the pi-th pixel in , y′ pi Represents image P b The ordinate value of the pi-th pixel in ;

[0025] Step 3: Let the width of the flexible piezoresistive material be W, the height be H, and H>W, take the center position of the flexible piezoresistive material as the coordinate origin, take an edge parallel to the flexible piezoresistive material as the x-axis, and take the direction perpendicular to the x-axis as the y-axis to establish a plane coordinate system;

[0026] Step 4: The host computer divides six square areas with a side length of L on the flexible piezoresistive material for defining command operations; the six square areas are respectively recorded as area A1, area A2, area A3, area A4, area A5, and area A6, and the corresponding geometric centers are respectively recorded as (x 1 ,y 1 )、(x 2 ,y 2 )、(x 3 ,y 3 )、(x 4 ,y4 )、(x 5 ,y 5 )、(x 6 ,y 6 );

[0027] Step 5: When the touch coordinates (x centre ,y centre ) In area A1, the touch command is defined as a wheelchair forward command;

[0028] When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair moves forward;

[0029] When the touch coordinates (x centre ,y centre ) In area A1, the wheelchair instruction is defined as the wheelchair moves forward;

[0030] When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair turns left;

[0031] When the touch coordinates (x centre ,y centre ) In area A3, the wheelchair instruction is defined as the wheelchair turns right;

[0032] When the touch coordinates (x centre ,y centre ) in area A4, the wheelchair instruction is defined as wheelchair moving backward;

[0033] When the touch coordinates (x centre ,y centre ) in area A5, the wheelchair instruction is defined as wheelchair acceleration;

[0034] When the touch coordinates (x centre ,y centre ) in area A6, the wheelchair instruction is defined as wheelchair deceleration;

[0035] Step 6, the host computer determines whether the flexible piezoresistive material has a touch action, if yes, execute step 7; otherwise, the host computer has no output;

[0036] Step 7: The host computer uses formula (5) to determine whether the touch coordinates are within the six square areas. If so, execute step 8; otherwise, the host computer has no output:

[0037]

[0038] Step 8: The host computer uses formula (6) to determine the wheelchair command and sends it to the wheelchair controller:

[0039]

[0040] Step 9: The wheelchair controller drives the wheelchair to perform corresponding actions according to the wheelchair instruction.

[0041] An electronic device of the present invention includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the wheelchair control method, and the processor is configured to execute the program stored in the memory.

[0042] The present invention provides a computer-readable storage medium, on which a computer program is stored. The computer-readable storage medium is characterized in that when the computer program is run by a processor, the steps of the wheelchair control method are executed.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The present invention has the characteristics of simple equipment operation, simple control method and low cost. By attaching a small amount of electrodes at the boundary of the flexible piezoresistive material, the boundary voltage information of the flexible piezoresistive material can be quickly detected by using the impedance acquisition circuit, and the impedance distribution information is further obtained through the imaging algorithm. Then, the user's control intention is judged and the control command is accurately transmitted to the wheelchair control unit, thereby realizing human-computer interactive control of the electric wheelchair only by using different touch commands.

[0045] 2. The electrical impedance technology used in the present invention is a non-destructive measurement technology. By attaching electrodes to the surface of the object to be measured and applying an adjustable external electrical excitation signal, it overcomes the shortcomings of brain waves and electromyographic signals being relatively weak and easily interfered with, thereby improving the stability of the control input system.

[0046] 3. The flexible piezoresistive material of the present invention is low-cost and flexible, and can be covered at any position of the wheelchair for command input. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a control system block diagram of the present invention;

[0048] Figure 2 This is a system block diagram of the electrode signal acquisition device of the present invention;

[0049] Figure 3 It is a diagram of placing electrodes of the flexible piezoresistive material of the present invention;

[0050] Figure 4 A region definition diagram for touch instructions of the present invention;

[0051] Figure 5 It is a control instruction diagram corresponding to different touch actions of the present invention;

[0052] Numbers in the figure: 1. Signal acquisition device; 2. Host computer; 3. Wheelchair controller; 4. Electrode; 5. Wire; 6. Analog switch; 7. Impedance chip; 8. Single chip microcomputer; 9. Wireless transmission module; 10. Power module. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0054] In this embodiment, a wheelchair control method based on electrical impedance technology combined with tactile perception is provided. Figure 1 As shown, it is applied to a control system composed of a signal acquisition device 1, a host computer 2 and a wheelchair controller 3, and includes the following steps:

[0055] Step 1: Figure 2 As shown, the signal acquisition device is designed, which mainly includes: an impedance chip 7, an analog switch 6, a single-chip microcomputer 8, a wireless transmission module 9, a power module 10, an electrode 4, and a wire 5;

[0056] like Figure 3 As shown, N electrodes 4 are attached to the flexible piezoresistive material 11 and are evenly distributed at the boundary of the flexible piezoresistive material. The analog switch 6 is used to control the conduction and disconnection between the impedance chip 7 and the electrode 4. The impedance chip 7 is used to output the detected excitation signal to the flexible piezoresistive material 11 and collect the voltage signal measured by the electrode. The single-chip microcomputer 8 is used to control the analog switch 6 and the voltage signal collected by the impedance chip 7 for processing and sending it to the host computer 2 through the wireless transmission module 9. The power supply module 10 is used to power the impedance chip 7, the analog switch 6, the single-chip microcomputer 8, and the wireless transmission module 9;

[0057] When there is no touch action on the flexible piezoresistive material 11, the voltage data between any two different electrodes among the N electrodes are measured in sequence, thereby obtaining The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is no touch action;

[0058] When there is a touch action on the flexible piezoresistive material, the voltage data between any two different electrodes among the N electrodes is not measured in sequence, so as to obtain The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is a touch action;

[0059] Step 2, the host computer 2 uses the TK-NOSER imaging method to perform two-dimensional imaging of the impedance distribution change in the flexible piezoresistive material 11;

[0060] Step 2.1: Use the open source software package Eidors to establish a finite element model of the flexible piezoresistive material and obtain the number of electrodes N of the finite element model. elec and the number of units M elem ; Let M elem The conductivity of the unit is Among them, σ m Denotes the conductivity of the mth unit, let V ij (σ) is the voltage between the i-th model electrode and the j-th model electrode under the conductivity distribution of σ; m=1,2,...,M elem ,i,j=1,2,...,N elec ;

[0061] Step 2.2: Calculate the sensitivity matrix J of the finite element model using formula (1):

[0062]

[0063] Step 2.3: Calculate the voltage difference data of the touch action ΔV = V 1 -V 0 ;

[0064] Step 2.4: Calculate the conductivity change Δσ of the flexible piezoresistive material corresponding to the finite element model unit using formula (2):

[0065] Δσ=(J T WJ+λ 2 R) -1 J T WΔV=RM·ΔV (2)

[0066] In formula (2), λ represents the hyperparameter, R represents the prior matrix obtained by NOSER prior, and W is the unit matrix;

[0067] Step 2.5, generating an M×M conductivity distribution image P according to the conductivity change Δσ;

[0068] Step 2.6: Perform threshold segmentation on the conductivity distribution image P to obtain the segmented binary image P b , where P b The pixel value of the rth row and cth column in is obtained using formula (3):

[0069]

[0070] In formula (3), P(r,c) represents the conductivity distribution image P, and t represents the threshold used for threshold segmentation;

[0071] Step 2.7: Use formula (4) to calculate the segmented binary image P b The geometric center coordinates (xcentre ,y centre ), and as touch coordinates:

[0072]

[0073] In formula (4), [P b ] pi Represents image P b The conductivity value at the pith pixel, x′ pi Represents image P b The horizontal coordinate value of the pi-th pixel in , y′ pi Represents image P b The ordinate value of the pi-th pixel in ;

[0074] Step 3: Figure 4 As shown, let the width of the flexible piezoresistive material be W, the height be H, and H>W, take the center position of the flexible piezoresistive material as the coordinate origin, take one side parallel to the flexible piezoresistive material as the x-axis, and take the direction perpendicular to the x-axis as the y-axis to establish a plane coordinate system; the size of the actual flexible piezoresistive material corresponds to the size of the finite element model of the flexible piezoresistive material;

[0075] Step 4: The host computer divides six square areas with a side length of L on the flexible piezoresistive material for defining command operations; the six square areas are respectively recorded as area A1, area A2, area A3, area A4, area A5, and area A6, and the corresponding geometric centers are respectively recorded as (x 1 ,y 1 )、(x 2 ,y 2 )、(x 3 ,y 3 )、(x 4 ,y 4 )、(x 5 ,y 5 )、(x 6 ,y 6 );

[0076] Step 5: When the touch coordinates (x c ,y c ) In area A1, the touch command is defined as a wheelchair forward command;

[0077] When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair moves forward;

[0078] When the touch coordinates (x centre ,y centre ) In area A1, the wheelchair instruction is defined as the wheelchair moves forward;

[0079] When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair turns left;

[0080] When the touch coordinates (x centre ,y centre ) In area A3, the wheelchair instruction is defined as the wheelchair turns right;

[0081] When the touch coordinates (x centre ,y centre ) in area A4, the wheelchair instruction is defined as wheelchair moving backward;

[0082] When the touch coordinates (x centre ,y centre ) in area A5, the wheelchair instruction is defined as wheelchair acceleration;

[0083] When the touch coordinates (x centre ,y centre ) in area A6, the wheelchair instruction is defined as wheelchair deceleration;

[0084] Step 6: The host computer determines whether the flexible piezoresistive material has a touch action. If so, step 7 is executed; otherwise, the host computer has no output;

[0085] Step 7: The host computer uses formula (5) to determine whether the touch coordinates are within the six square areas. If so, execute step 8; otherwise, the host computer has no output:

[0086]

[0087] Step 8: The host computer uses formula (6) to determine the wheelchair command and sends it to the wheelchair controller:

[0088]

[0089] Step 9: The wheelchair controller drives the wheelchair to perform corresponding actions according to the wheelchair instruction.

[0090] like Figure 5 As shown, it is the control intention of different touch actions. Take the forward command as an example: press the area where the forward command is set, collect the corresponding signal for EIT imaging, and then extract the pressed position. Since the touch area is within the A1 range, the host computer sends the forward command to the wheelchair controller. In addition, the control instructions provided by the present invention are not limited to the proposed forward, right turn, left turn, backward, stop, and acceleration; the defined command area can be customized according to the user's personalized needs;

[0091] In summary, the present invention discloses a wheelchair control method based on electrical impedance technology combined with tactile perception, which includes a flexible piezoresistive material, a signal acquisition device, and a host computer. The material used in the method is a flexible conductive material, which can be coated on the surface of a complex three-dimensional object in a large area to detect touch actions, and has the characteristics of a very simple structure, high sensitivity, simple control, good stability, and low cost.

[0092] In this embodiment, an electronic device includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the wheelchair control method, and the processor is configured to execute the program stored in the memory.

[0093] In this embodiment, a computer-readable storage medium stores a computer program on the computer-readable storage medium, and the computer program executes the steps of the wheelchair control method when executed by a processor.

[0094] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wheelchair control method based on electrical impedance technology combined with tactile perception, characterized in that It is applied to a control system composed of a wheelchair controller, a signal acquisition device and a host computer, and includes the following steps: Step 1, designing the signal acquisition device, including: an impedance chip, an analog switch, a single-chip microcomputer, a power module, electrodes and a flexible piezoresistive material; N electrodes are attached to the flexible piezoresistive material and are evenly distributed at the boundaries of the flexible piezoresistive material. The analog switch is used to control the conduction and disconnection between the impedance chip and the electrodes. The impedance chip is used to output the detected excitation signal to the flexible piezoresistive material and collect the voltage signal measured by the electrode. The single-chip microcomputer is used to control the analog switch and process the voltage signal collected by the impedance chip. The power module is used to power the impedance chip, the analog switch, and the single-chip microcomputer. When there is no touch action on the flexible piezoresistive material, the voltage data between any two different electrodes among the N electrodes are measured in sequence, thereby obtaining The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is no touch action; When a touch action is performed on the flexible piezoresistive material, the voltage data between any two different electrodes among the N electrodes are not measured in sequence, so as to obtain The voltage value is recorded as in, Indicates the voltage value between the N-1th electrode and the Nth electrode when there is a touch action; Step 2: The host computer uses the TK-NOSER imaging method to perform two-dimensional imaging of the impedance distribution change in the flexible piezoresistive material; Step 2.1: Use the open source software package Eidors to establish a finite element model of the flexible piezoresistive material and obtain the number of electrodes N of the finite element model. elec and the number of units M elem ; Let M elem The conductivity of the unit is Among them, σ m Denotes the conductivity of the mth unit, let V ij (σ) is the voltage between the i-th model electrode and the j-th model electrode under the conductivity distribution of σ; m=1,2,...,M elem ,i,j=1,2,...,N elec ; Step 2.2: Calculate the sensitivity matrix J of the finite element model using formula (1): Step 2.3, calculate the voltage difference data of the touch action ΔV=V1-V0; Step 2.4: Calculate the conductivity change Δσ of the flexible piezoresistive material corresponding to the finite element model unit using formula (2): Δσ=(J T WJ+λ 2 R) -1 J T WΔV=RM·ΔV (2) In formula (2), λ represents the hyperparameter, R represents the prior matrix obtained by NOSER prior, and W is the unit matrix; Step 2.5, generating an M×M conductivity distribution image P according to the conductivity change Δσ; Step 2.6: Perform threshold segmentation on the conductivity distribution image P to obtain the segmented binary image P b , where P b The pixel value of the rth row and cth column in is obtained using formula (3): In formula (3), P(r,c) represents the pixel value of the rth row and cth column in the conductivity distribution image P, and t represents the threshold used for segmentation; Step 2.7: Use formula (4) to calculate the segmented binary image P b The geometric center coordinates (x centre ,y centre ), and as touch coordinates: In formula (4), [P b ] pi Represents image P b The conductivity value at the pith pixel, x′ pi Represents image P b The horizontal coordinate value of the pi-th pixel in , y′ pi Represents image P b The ordinate value of the pi-th pixel in ; Step 3: Let the width of the flexible piezoresistive material be W, the height be H, and H>W, take the center position of the flexible piezoresistive material as the coordinate origin, take an edge parallel to the flexible piezoresistive material as the x-axis, and take the direction perpendicular to the x-axis as the y-axis to establish a plane coordinate system; Step 4: The host computer divides six square areas with a side length of L on the flexible piezoresistive material for defining instruction operations; the six square areas are respectively recorded as area A1, area A2, area A3, area A4, area A5, and area A6, and the corresponding geometric centers are respectively recorded as (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5), and (x6, y6); Step 5: When the touch coordinates (x centre ,y centre ) In area A1, the touch command is defined as a wheelchair forward command; When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair moves forward; When the touch coordinates (x centre ,y centre ) In area A1, the wheelchair instruction is defined as the wheelchair moves forward; When the touch coordinates (x centre ,y centre ) In area A2, the wheelchair instruction is defined as the wheelchair turns left; When the touch coordinates (x centre ,y centre ) In area A3, the wheelchair instruction is defined as the wheelchair turns right; When the touch coordinates (x centre ,y centre ) in area A4, the wheelchair instruction is defined as wheelchair moving backward; When the touch coordinates (x centre ,y centre ) in area A5, the wheelchair instruction is defined as wheelchair acceleration; When the touch coordinates (x centre ,y centre ) in area A6, the wheelchair instruction is defined as wheelchair deceleration; Step 6, the host computer determines whether the flexible piezoresistive material has a touch action, if yes, execute step 7; otherwise, the host computer has no output; Step 7: The host computer uses formula (5) to determine whether the touch coordinates are within the six square areas. If so, execute step 8; otherwise, the host computer has no output: Step 8: The host computer uses formula (6) to determine the wheelchair command and sends it to the wheelchair controller: Step 9: The wheelchair controller drives the wheelchair to perform corresponding actions according to the wheelchair instruction.

2. An electronic device, comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the wheelchair control method according to claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the wheelchair control method according to claim 1 are executed.

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